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IC
9025
Bureau of Mines Information Circular/1985
Tungsten Availability— Market
Economy Countries
A Minerals Availability Program Appraisal
By T. F. Anstett, D. I. Bleiwas,
and R. J. Hurdelbrink
UNITED STATES DEPARTMENT OF THE INTERIOR
CD
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33
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751
*f/NES 75TH A^
Information Circular 9025
A
t^JjU M*&< , fUnuM *£ Hm^
Tungsten Availability— Market
Economy Countries
A Minerals Availability Program Appraisal
By T. F. Anstett, D. I. Bleiwas,
and R. J. Hurdelbrink
UNITED STATES DEPARTMENT OF THE INTERIOR
Donald Paul Hodel, Secretary
BUREAU OF MINES
Robert C. Horton, Director
As the Nation's principal conservation agency, the Department of the Interior
has responsibility for most of our nationally owned public lands and natural
resources. This includes fostering the wisest use of our land and water re-
sources, protecting our fish and wildlife, preserving the environmental and
cultural values of our national parks and historical places, and providing for
the enjoyment of life through outdoor recreation. The Department assesses
our energy and mineral resources and works to assure that their development is
in the best interests of all our people. The Department also has a major re-
sponsibility for American Indian reservation communities and for people who
live in Island Territories under U.S. administration.
^■{vlE^
^ -0
*V
4<
Library of Congress Cataloging in Publication Data:
Anstett, T 4 F. (Terrance F.)
Tungsten availability —market economy countries.
(Information circular ; 9025)
Bibliography: 51;
Supt. of Docs, no.: I 28.27:9025.
1. Tungsten industry. I. Bleiwas, Donald I. II. Hurdelbrink,
Ronald J. III. Title. IV. Series: Information circular (United States.
Bureau of Mines) ; 9025.
TN295.U4 [HD9539.T8] 622s [338 6 2'74649] 84-600367
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402
«• PREFACE
• ' The Bureau of Mines is assessing the worldwide availability of nonfuel critical
minerals. The Bureau identifies, collects, compiles, and evaluates information on active,
developed, and explored mines and deposits and mineral processing plants worldwide.
Objectives are to classify domestic and foreign resources, to identify by cost evaluation
resources that are reserves, and to prepare analyses of mineral availability.
This report is part o\' a continuing series of reports that analyze the availability
of minerals from domestic and foreign sources. Questions about these reports should
ssed to Chief. Di\ ision of Minerals Availability. Bureau of Mines, 2401 E Street,
XV ..on. DC 20241.
in
M
CONTENTS
Page
Preface iii
Abstract 1
Introduction 2
Tungsten products and uses 2
Tungsten pricing 3
Tungsten concentrate price indicators 3
Price indicators for tungsten products 4
World tungsten production, consumption, and
trade 5
Production and consumption 5
World trade 5
U.S. production, consumption, and imports 6
Geology and resources 7
Evaluation methodology 7
Geology of tungsten deposits 9
Market economy countries 10
Australia 10
Austria 12
Bolivia 13
Brazil 15
Burma 15
Canada 15
France 16
Mexico 17
Namibia 17
Peru 18
Portugal 18
Republic of Korea 18
Spain 18
Sweden 19
Thailand 19
Turkey 19
Uganda 20
United Kingdom 20
United States 20
Centrally planned economy countries 22
China' 22
U.S.S.R 23
Mining and postmine processing technology 24
Mining methods 24
Surface 24
Underground 26
Solution 26
Beneficiation of tungsten ores 26
Page
Post mill processing 28
Ammonium paratungstate (APT) 28
Artificial scheelite 29
Scheelite concentrate 30
Ferrotungsten 30
Operating and capital costs 31
Operating costs 31
Surface and underground 31
Regional overview 32
Producers 32
Nonproducers 33
Producers versus nonproducers 33
Postmill transportation and processing 33
Transportation 34
Processing costs 34
Ammonium paratungstate (APT) 34
Ferrotungsten 35
Artificial scheelite 35
Scheelite concentrate 35
Capital costs 36
Mine and mill capital ' 36
Postmill capital 36
Ammonium paratungstate (APT) 37
Ferrotungsten 37
Artificial scheelite 37
Tungsten availability— market economy countries . 37
Evaluation methodology 38
Tungsten availability 40
Scheelite concentrate 40
Total availability 41
Annual availability 42
Ammonium paratungstate (APT) 42
Total availability 42
Annual availability 44
Ferrotungsten 45
Total availability 46
Annual availability 46
Tungsten availability— all product forms
combined 46
Total availability 46
Annual availability 47
Conclusions 49
References 51
ILLUSTRATIONS
1. Simplified tungsten flow diagram 2
2. World annual tungsten concentrate production and consumption, 1973-82 5
3. MEC and CPEC production and consumption of tungsten concentrate, 1973-82 6
4. World tungsten trade pattern, early 1980's 6
5. U.S. annual tungsten production, consumption, and import data, 1973-82 7
6. Sources of tungsten ore and concentrate imports to the United States, 1973-82 7
7. Classification of mineral resources 9
8. Demonstrated contained WO, resources for MEC deposits evaluated 11
9. Location map, Australian deposits 11
10. Location map, European deposits 13
11. Location map. South American deposits 13
12. Location map. southeast Asian deposits 15
13. Location map, Canadian deposits 16
14. Location map. Mexican and U.S. deposits 17
VI
CONTENTS— Continued
Page
15. Location map, southern African deposits 17
16. Total recoverable resource by status and mine type 25
17. Total ore capacity by status and mine type . . . : 25
18. Flowsheet, Mount Carbine operation 27
19. Flowsheet, Sangdong concentration process 28
20. Flowsheet, ammonium paratungstate production process 29
21. Flowsheet, artificial scheelite production process 29
22. Flowsheet, ferrotungsten production process 30
23. Operating costs, surface versus underground 31
24. Operating costs, regional basis 32
25. Estimated mine capital for selected undeveloped properties 36
26. Minerals Availability Program evaluation procedure 38
27. Total production costs 39
28. Total W0 3 potentially available from scheelite producers at 15- and 0-pct DCFROR's 41
29. Annual W0 3 potentially available from scheelite producers at various average total costs 42
30. W0 3 potentially available as ammonium paratungstate 43
31. Total W0 3 potentially available from ammonium paratungstate producers at 15- and 0-pct DCFROR's . . 44
32. Total W0 3 potentially available from ammonium paratungstate nonproducers at 15- and 0-pct
DCFROR's 44
33. Annual W0 3 potentially available from ammonium paratungstate producers at various average total
costs 45
34. Annual W0 3 potentially available from ammonium paratungstate nonproducers at various average total
costs 45
35. Total W potentially available from ferrotungsten deposits at 15- and 0-pct DCFROR's 46
36. Annual MEC W0 3 availability and projected demand, 1983-95 48
TABLES
1. Tungsten prices 4
2. MEC tungsten deposit information 8
3. MEC tungsten demonstrated resources used for analysis, January 1983 10
4. CPEC in situ resources, January 1983 23
5. Mine ore capacity, mining and beneficiation methods, product, and status 24
6. Chemical composition of APT 29
7. Chemical composition of natural and artificial scheelite 30
8. Chemical composition of ferrotungsten 30
9. Commodity prices used in study 32
10. Actual or assumed destinations for tungsten concentrate 34
11. Port handling and transportation costs for selected major tungsten concentrate trade routes 35
12. Estimated operating costs for a 2-million lb/yr APT plant 35
13. Estimated operating costs for a 1,000-t/yr ferrotungsten plant 35
14. Estimated operating costs for a 1-million-lb/yr (W0 3 ) artificial scheelite plant 35
15. Estimated capital costs for a 2-million-lb/yr (W0 3 ) APT plant 37
16. Estimated capital costs for a 1,000-t/yr ferrotungsten plant 37
17. Estimated capital costs for a 1-million-lb/yr artificial scheelite plant 37
18. U.S. market price for tungsten concentrates 41
19. U.S. market price for APT 43
20. U.S. market price for ferrotungsten 46
LIST OF UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT
°c
degree Celsius
m 2
square meter
cm
centimeter
mm
millimeter
ha
hectare
pet
percent
kg
kilogram
ppm
parts per million
km
kilometer
t
metric ton
km 2
square kilometer
t/d
metric ton per day
kW-h
kilowatt hour
tr oz
troy ounce
lb
pound
t/yr
metric ton per year
lb/yr
pound per year
wt pet
weight percent
m
meter
yr
year
TUNGSTEN AVAILABILITY— MARKET ECONOMY COUNTRIES
A Minerals Availability Program Appraisal
By T.F. Anstett, 1 D.I. Bleiwas, 1 and R.J. Hurdelbrink 2
ABSTRACT
The Bureau of Mines estimated the potential availability of tungsten from 57 mines
and deposits in 19 market economy countries. The tungsten resources of China and the
U.S.S.R. were also estimated. This resulted from an evaluation of tonnage-cost rela-
tionships indicating the quantity of tungsten available as ammonium paratungstate
| APT), artificial and natural scheelite, and ferrotungsten at various average total costs
of production including 0- and 15-pct rates of return on invested capital..
The evaluated deposits contain 1.2 million metric tons (t) of recoverable W0 3 , of
which approximately 52,000 t of APT can be produced at the January 1983 market price
of $5.37 lb. 89,000 t of natural and artificial scheelite at a market price of $3.63/lb, and
1,700 t of feiTotungsten at $5.61/lb of tungsten. An annual availability analysis indicates
that by the early 1990's new deposit discoveries, development of known prospects, or
expansions of producing mines will be necessary to meet projected tungsten demand.
'Geol> _
industry economist
Minerals Availability Field Office. Bureau of Mines. Denver. CO.
INTRODUCTION
Tungsten is a metal critical to modern industry, chiefly
owing to the ability of the metal to retain great hardness
at high temperatures. For this reason it is an important
constituent of high-speed drilling, cutting, and milling tools.
This Bureau of Mines study addresses the potential
availability of tungsten as ammonium paratungstate (APT),
natural and artificial scheelite, and ferrotungsten from 57
mines and deposits in 19 market economy countries
(MEC's). The study evaluates the geologic, engineering, and
economic factors affecting the potential availability from
the 57 MEC mines and deposits, and addresses the resources
of 38 tungsten deposits in two centrally planned economy
countries (CPEC's), China and the U.S.S.R.
The major production cost factors affecting the
availability of tungsten from each deposit are part of this
evaluation, including mining and beneficiation costs; pro-
cessing costs for APT, artificial and natural scheelite, and
ferrotungsten; and costs of transportation.
TUNGSTEN PRODUCTS AND USES
Tungsten was first isolated from its ore minerals in the
1780's, although the name was first used in 1755. The first
significant industrial application was in tungsten-
manganese steel in the mid-19th century. Worldwide, most
tungsten is marketed in four major intermediate forms: con-
centrate, APT (the major intermediate product in the United
States), ferrotungsten, and artificial scheelite. Virtually all
other tungsten products are derived from these forms and
from scrap, as illustrated in figure 1.
Concentrate is either converted into intermediate
products such as APT, or, in the case of some scheelite con-
centrates, used as a direct additive to molten steel. In order
to be an acceptable additive, the concentrate must meet
strict assay requirements. Some concentrate is converted
directly into tungsten carbide powder.
The addition of natural or artificial scheelite to steel
imparts properties of greater hardness, wear resistance, and
high heat resistance. It is an important constituent of steel
Tungsten
ore
Tungsten
concentrate
Artificial
scheelite
Scrap
Ferro-
tungsten
Scrap
Superalloys
Tungsten
metal
powder
Tungsten
carbide
(powder,
cast,
crystalline)
Carbide
tools
and wear-
resisting
materials
--J
Tungsten
mill
products
Tungsten
chemicals
Chemicals
and
ceramics
Figure 1 .—Simplified tungsten flow diagram.
for tools, drill bits, and other similar applications. In some
cases, artificial scheelite can be used as a direct additive
to steel baths.
Nearly all APT is reduced to tungsten metal powder,
most of which is used to produce tungsten carbide powder.
Most of the remaining metal powder is used for a large
variety of different products. Tungsten carbide accounts for
more than 60 pet of total tungsten consumption in the
United States. The tungsten carbide is cemented, usually
with cobalt, to form various cutting and wear-resistant
cemented carbide products. Most tungsten carbide is used
for metalworking machinery and by the mining and oil in-
dustries for which tungsten carbide's high melting point,
high compressive strength, hardness, and resistance to ox-
idation are necessary, particularly for working metals at
high speeds.
The major use of tungsten metal powder is in wire, rod,
and sheet form as filaments in electric lamps and other
purposes, but it is also used for electrical contacts, welding
rods and electrodes, and armor-piercing ammunition.
TUNGSTEN PRICING
In contrast to what happens in many basic commodity
markets, there are no terminal market quotations for
tungsten ore. Almost all transactions involve a milled or
processed form of tungsten with sales negotiated between
producers and consumers or merchants and users. Terms
of purchase can vary with every sale. There are prices
reported on a regular or semiregular basis for tungsten con-
centrate, tungsten metal powder, tungsten carbide powder,
and feiTotungsten. and additional information about actual
prices paid can be gleaned from national trade statistics.
However, none of these prices are normally used for pric-
ing purposes 'except the concentrate price! and could be bet-
ter described as price indicators.
This near lack of a common pricing basis reflects the
wide variation in the chemical makeup of tungsten
materials, as well as the diversity of requirements for
different users with respect to impurities and tungsten con-
tent for each of the possible tungsten products. Those con-
tracts that do use a published concentrate price as a basis
adjust the actual price paid to reflect such things as con-
taminants, tungsten content, tariff barriers, and the par-
ticular needs of the purchaser.
TUNGSTEN CONCENTRATE PRICE INDICATORS
There are three regularly published price indicators for
tungsten concentrates, the Metal Bulletin, the International
Tungsten Indicator
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1977 1978
YEAR
Figure 3. — MEC (top) and CPEC (bottom) production and con-
sumption of tungsten concentrate, 1973-82.
pet of world production between 1973 and 1982, and pro-
duced 21 to 29 pet of the world total over the same period.
The excess production made China the most important
world supplier throughout the period, while earning
substantial amounts of foreign currency and enhancing the
country's balance of payments position.
Many factors affect the pattern of world production and
trade. Export and import taxes, for example, may determine
the location of tungsten processing facilities. Bolivia taxes
the export of processed mineral products more heavily than
ore and concentrate, a factor that probably accounts for the
fact that a large percentage of Bolivian exports are in con-
centrate form. Probably more common are tax incentives
that encourage mineral processing facilities to locate within
a country. The United States, for example, taxes the im-
port of processed tungsten products much more heavily than
the import of ore and concentrates.
Another factor affecting world trade, but which is dif-
ficult to quantify, is smuggling. It is likely, for example,
that a substantial amount of production from Thailand is
not officially accounted for and probably is illegally
transported out of the country, but nevertheless enters the
world market. These and other nontariff factors (e.g., im-
port quotas) can add significantly to the delivered cost of
tungsten ore, concentrate, or products, and affect world
trade patterns.
U.S. PRODUCTION, CONSUMPTION,
AND IMPORTS
Figures 5 and 6 show production, consumption, and im-
port data for the United States for the 1973 to 1982 period.
Production from U.S. mines (fig. 5) has been far below
reported domestic consumption, averaging only 37 pet of
consumption over the 1973 to 1982 period. Imports for con-
sumption accounted for an average of 54 pet of U.S. con-
sumption over the same period. Other sources of tungsten
to the United States include scrap, and releases from the
General Services Administration (GSA) stockpile of
strategic and critical materials.
Figure 6 is a graph showing U.S. imports of tungsten
ore and concentrate, by exporting country, for 1973 to 1982.
Bolivia, Canada, Peru, and Thailand have been relatively
constant suppliers of sizable amounts to the United States.
Mexico and Peru have been steady suppliers over the time
LEGEND
-•— 500 1 of tungsten
<3= I.OOOt of tungsten
C~\ 10,000 1 of tungsten
Figure 4.— World tungsten trade pattern, early 1980s.
KEY
I I Shipments from U S Government stocks
! ' U S imports for consumption
V/A U S mine production
period, but smaller amounts of imports from those countries
do not show up during some years because of the cutoff
levels used to make the graph. Australia and the Republic
of Korea have been steady suppliers as well, but at levels
too low to show up on the graph. Although the United States
imported small amounts of tungsten from China in every
year of the time period shown on the graph, since 1978, the
country has been an increasingly important source. The
lowest proportion was in 1973, when Chinese tungsten ac-
counted for 1 pet of U.S. imports. China's share increased
steadily through 1981, when a level of nearly 22 pet was
attained. However, 1981 was an unusual year in terms of
Canadian exports owing to the reduced output from Can-
tung (because of a labor strike), that country's primary
source of tungsten. Canada's 1982 share increased to a more
historically typical level, at 32 pet of total U.S. imports.
1978 1979
Figure 5. — U.S. annual tungsten production, consumption, and
import data. 1973-82.
'977 I978
YEAR
Figure 6.— Sources of tungsten ore and concentrate imports to the United States, 1973-82.
GEOLOGY AND RESOURCES
A total of 57 MEC and 38 CPEC mines and deposits
were analyzed for their tungsten resources. Additionally,
the MEC deposits were evaluated for their cost of produc-
tion using the Bureau's supply analysis model (SAM)
economic evaluation methodology (4). Table 2 is a list of
MEC depoeite analyzed, along with geologic type, owner-
ship, and production status.
EVALUATION METHODOLOGY
Selection of deposits was based on discussions with the
Bureau of Mines tungsten specialist, field center personnel,
and personnel from the private sector. All major known
primary tungsten deposits in MEC's were included, with
at least 85 pet of known resources and 85 pet of current pro-
duction capacity accounted for.
Table 2.— MEC tungsten deposit information
Location and deposit'
California:
Adamson 1
Andrew 2 . .
Atolia Placers 3 . .
Pine Creek 4 . .
Strawberry 5 . .
Idaho: Thompson Creek 6
Nevada:
Emerson 7 . .
Indian Springs 8 . .
Nevada Scheelite 9 . .
Pilot Mountain 10
Springer 11 .
North Carolina: Tungsten Queen ... ,12 .
Australia:
Kara 13 .
King Island 14 .
Mount Carbine 15 .
Mount Mulgine 16
Torrington 17 .
Austria: Mittersill 18 .
Bolivia:
Bolsa Negra 19 .
Chambillaya 20
Chicote Grande 21 .
Chojlla 22
Enramada 23
Kami 24 .
Pueblo Viejo 25 .
Tasna 26 .
Viloco 27 .
Brazil:
Barra Verde 28
Boca de Lage 29
Brejui 30 .
Zangarelhas 31 .
Burma: Mawchi 32
Canada:
Cantung 33 .
Logtung 34 .
Mactung 35
Mount Pleasant 36
France:
Montredon 37
Salau 38
Mexico:
Baviacora 39
Los Verdes 40
San Alberto 41
Namibia:
Brandberg West 42
Krantzberg 43
Peru: Pasto Bueno 44
Portugal:
Borralha 45
Panasquiera 46
Republic of Korea: Sangdong 47
Spain:
Barruecopardo 48
La Parilla 49
Santa Comba 50
Sweden: Yxsjoberg 51
Thailand:
Doi Mok 52
Doi Ngoem 53
Khao Soon 54
Turkey: Uludag 55
Uganda: Nyamalilo 56
United Kingdom: Hemerdon 57
Type
Owner and/or operator
Status
Tactite .
Talus . .
Alluvial
Tactite .
... do
... do
... .do
Tactite, stockwork
. ... do
Tactite
do
Vein
Tactite . . . .
do
Veinlet . . . .
do
Sills, dikes
Stratiform
Vein-manto
Vein
. .do
..do
do ...
. . do ...
. . do ...
. . do ...
. . do ...
Tactite .
. do
... do
... do
Vein . . .
Tactite
Vein, stockwork
Tactite
Porphyry
Vein
Tactite .
do . .
Porphyry
Tactite . .
do
Vein
. . . .<
Vein . .
Vein . . .
do.
Tactite .
Porphyry
Vein
.... do . .
Tactite . .
Vein
do
.... do
Tactite
Stratabound vein .
Veinlets
Panaminas , . . . .
Curtis Tungsten Inc
H.W. Hobbs, Mines Exploration. Inc.
Union Carbide
Teledyne
R.M. Barrett
Teledyne, N. Tempiute, Union Carbide
Utah International
Natural Resources Development Inc.
Union Carbide
Utah International (GE)
Ranchers Exploration & Development .
Tasminex, Mclntyre Mines
Peko-Wallsend Ltd
Queensland Wolfram Ltd
Minefields Exploration
Barix Pty. Ltd
Metallgesellschaft, Voest-Alpine
Comibol
International Mining Co
Churquini Enterprises Inc
International Mining Co
.... do
Comibol
Sra. Eva Thiel de Sara
Comibol
do
Mineracao Sertaneja Ltda
Tungs do Brasil Min e Met
Mineracao Tomas Salustino S.A.
Tungs do Brasil Min e Met
Burmese Government
Canada Tungsten Mining Corp. .
AMAX, Logtung
AMAX Northwest Mining Co. Ltd.
Billiton Canada, Sullivan Mng . .
Bur Res Geol and Min, Penarroya
Co Met and Min, L. O'mnivini des Min.
Tungsteno de Baviacora SA
Cia Minera Coronado S.A. de CV
Draco
SW Africa Ltd. (Goldfields)
Nord Resources, Bethlehem Steel
Fermin Malaga Y Santolalla
Minas da Borralha Sari
Serra d Estrela
Korea Tungsten Mining Co. Ltd.
Coto Minero Merladet S.A
Minero Bonilla
Coparex Minera S.A
Luossavaara Kiirunavaara AB . .
Sirithai Scheelite
Parasit Mining Co
Siamencan Mining Co. Ltd.
Etibank
Ugandan Government ....
AMAX, Hemerdon Mining .
P
P
PP
P
P
PP
P
N
P
PP
P
PP
P
P
P
N
N
P
P
P
P
P
P
P
P
P
P
P
P
P
N
P
P
N
N
N
PP
P
P
N
P
PP
PP
P
P
P
P
P
P
P
P
N
P
PP
P
PP
N
N Nonproducer. P Producer. PP Past producer.
'Numerals refer to sites on location maps (figs. 10-16).
Cumulative
production
ECONOMIC
MARGINALLY
ECONOMIC
SUBECONOMIC
IDENTIFIED RESOURCES
Demonstrated
Measured
Indicated
Reserve
base
Inferred
Inferred
reserve
base
UNDISCOVERED RESOURCES
Probability range
(or)
Hypothetical
Speculative
+
+
Other
occurrences
Includes nonconventional and low-grade materials
Figure 7. — Classification of mineral resources.
The evaluation of these 57 deposits was done on resource
values sufficiently defined to be considered demonstrated
according to the definitions established by the Bureau of
Mines and the Geological Survey {5) "fig. 7). Although an
attempt was made to acquire resource information at the
inferred level, adequate data were generally difficult to
obtain: thus, inferred resources are not addressed in this
report. Demonstrated resource data were readily available
for most MEC deposits, either from published sources
| Bureau. U.S. Geological Survey, State, and industry
publications; professional journals; and company annual
reports and lOK'si and contacts with deposit owners, or from
individuals and government agencies with personal
knowledge of the deposit. All resources evaluated can be
mined and beneficiated using current technology.
Principal Chinese and Soviet (i.e., major CPEC tungsten
producers ) deposits are included in the study, but were not
subjected to cost evaluation owing to a general paucity of
sufficiently documented resource data, and problems in col-
lecting production costs and coverting costs to U.S. dollar
equivalents.
GEOLOGY OF TUNGSTEN DEPOSITS
Tungsten occurs in three main types of economically
important deposits: <1) contact metamorphic-metasomatic
scheelite-bearing tactites, or skarns, <2) wolframite-bearing
quartz veins, and (3) deposits of volcanogenic origin
Tungsten also occurs in pegmatites, placers, brines, and
ts associated with porphyries.
Although about 20 tungsten-bearing minerals are
n. tungsten mineralogy is quite simple, and the
economically important minerals can be categorized into
olframite and .scheelite. The wolframite group
contains three ore minerals that form a continuous solid-
solution series of iron-manganese tungstates, with ferberite
(FeWO„) and huebnerite (MnWOj as end members, and
wolframite [(Fe, Mn) WOJ as an intermediate member. The
scheelite group contains only one economically important
member, CaW0 4 , which accounts for about 50 pet of the
world's known deposits (6, p. 182).
In general, tungsten mineralization is genetically
associated with felsic igneous rocks such as granodiorite,
quartz monzonite, and granite. There is a strong associa-
tion of tungsten occurrences with orogenic fold belts, par-
ticularly the Mesozoic-Tertiary Alpine-Himalayan (e.g.,
Nanling Range, China) and Circum-Pacific systems (e.g.,
Bolivian Andes, North American Sierra Nevada); however,
some tungsten is found in Precambrian shield areas of
eastern Canada, eastern Brazil, Australia, and parts of
Africa (7).
Tactites, numerically the most common form of
tungsten deposit, are formed through high-temperature
replacement and recrystallization of calcareous sedimen-
tary rocks at or near the contact with an igneous intrusion.
They typically are located near to the higher parts of the
intrusive. Tactites generally have distinct boundaries, but
scheelite mineralization is usually erratically distributed
throughout the ore body, and can range in size from small
isolated pods to massive bodies. Although tactite bodies are
frequently small and irregular in shape, the largest known
tungsten occurrence, Shizhuyuan, China, contains an
estimated 627,000 t of WO-, in limestone beds in contact
with a granitic intrusion. Sulfide minerals often found in
association with scheelite in tactites include pyrrhotitc,
chalcopyrite, and sphalerite, commonly with a calc-silicate
gangue. Important tactite deposit evaluated for this study
include Sangdong in the Republic of Korea, Pine Creek in
California, and Cantung in Canada.
10
Tungsten-bearing vein deposits are widely distributed
geographically, and account for more than 60 pet of the
world's reserves (8). The veins occur as discrete bodies, vein
swarms, or stockworks, usually found in roof zones
associated with acidic igneous intrusions. Tungsten is
mainly present as wolframite, huebnerite, or ferberite, but
scheelite may also occur. Associated minerals often include
cassiterite, arsenopyrite, and bismuthinite. Mineralization
is usually erratically distributed, but can occur as localized,
isolated pockets along an extensive vein. Stockwork or
veinlet deposits can be quite large. For example, Logtung,
Canada, contains more than 195,000 t of W0 3 . The greatest
commercial concentration of vein-type deposits is in the
southeastern portion of China, where the famous
Xihuashan Mine is located. Other well known vein deposits
evaluated for this study include all of those in Bolivia and
Thailand. Tungsten deposits associated with porphyries in-
clude the tungsten-molybdenum property at Mount Plea-
sant in New Brunswick, Canada, and Climax in Colorado,
which produces tungsten as a byproduct of molybdenum
mining. These deposits, although genetically related to ig-
neous bodies, do not occur as tactites or discrete vein
systems. They are typically quite large (e.g., Mount Plea-
sant contains nearly 72,000 t of W0 3 ), and display zonation
of mineral type.
Two deposits of unique geologic character include Mit-
tersill in Austria and Searles Lake, California. Mittersill
is a stratiform deposit that appears to have been related
to submarine volcanic activity. Searles Lake, one of the
largest known potential sources of tungsten in the United
States, is a brine deposit.
MARKET ECONOMY COUNTRIES
Table 3 and figure 8 contain demonstrated resource in-
formation for the 57 MEC deposits evaluated. MEC's
account for nearly 45 pet of the total amount of tungsten
contained in deposits addressed in this study.
Following is a discussion of deposits analyzed, by
country, addressing geology, resources, and other signifi-
cant information relating to assumptions used for this
study. Where the term "reserves" is used, it was taken
directly from the published article cited, and does not
necessarily conform to the meaning of that term as defined
by the Bureau of Mines and Geological Survey (5) (fig. 7).
Some published resource figures cited in the individual
country discussions differ slightly from figures used in the
analysis (table 3).
Australia
Australia is one of the largest MEC tungsten producers,
with an estimated 6.4 million lb of W0 3 produced in 1982
(9). Over 90 pet of the country's production is from two
mines, the King Island scheelite mine on King Island,
Table 3.— MEC tungsten demonstrated resources used for analysis, January 1983
Location and deposit
In situ
resources,
10 6 t
In situ
grade,
pet WQ 3
Contained WQ 3
2 pct
Recoverable WQ 3
In prod-
uct, t
pet
Source 1
Australia:
Kara
King Island
Mount Carbine
Mount Mulgine
Torrington
Total or average .
Austria: Mittersill
Bolivia:
Bolsa Negra
Chambillaya
Chicote Grande . . .
Chojlla
Enramada
Kami
Pueblo Viejo
Tasna
Viloco
Total or average .
Brazil"
Burma: Mawchi
Canada:
Cantung
Logtung
Mactung
Mount Pleasant . . .
Total or average .
France:
Montredon
Salau
Total or average .
1.0
7.6
24.5
37.0
6.0
4.8
.6
0.73
1.03
.10
.19
.20
.68
.53
.50
7,300
78,280
24,500
70,300
12,000
.5
1.04
5,200
.5
.58
2,900
2.4
.80
19,200
2.8
.40
1 1 ,200
.5
.80
4,000
.6
.97
5,820
.1
1.09
1,090
.4
.84
3,360
( 3 )
1.50
670
53,440
3.0
25,440
3,000
1.5
.2
3,452
34,177
22,982
42,642
6,350
76.1
.25
192,380
11.0
109,603
9.1
4.5
.50
22,500
1.3
15,787
1.3
1,562
1,786
12,485
5,924
2,568
3,620
897
1,110
279
30,231
16,214
1,087
2.6
1.32
34,320
25,884
163.0
.12
195,600
154,202
57.0
.96
547,200
412,700
26.5
.27
71,550
45,871
2.5
1.3
.1
249.1
.34
848,670
48.4
638,657
53.0
2.0
.9
.63
1.40
12,600
12,600
6,841
8,576
2.9
.87
25,200
1.4
15,417
1.3
2, 3
2, 3
2
1, 3
2, 3
2, 3
1, 3
3
2, 3
1, 5
3
2
2
2
2
2, 3
2, 3
See explanatory notes at end ot table.
11
Table 3.— MEC tungsten demonstrated resources used for analysis. January 1983— Continued
Location and deposit
In situ
resources,
101
In situ
grade.
pet WQ 3
Contained W0 3
2 pct
R>\ overable WO
In prod-
uct, t pet
Source'
Mexico 4
Namibia:
Braodberg West
Krantzberg
Total or average
Peru Pasto Bueno
Portugal.
Borralha
Panasquie-a
Total or average
Republic of Korea Sangdong
Spam
-ecopardo
La Paniia
Santa Comba
Total or average
Sweden Yxstoberg
Thailand
Dot Mok
Doi Ngoem
Khao Soon
4.7
0.45
21.150
1.2
7.901
0.7
2.4
.9
.20
40
4.800
3.600
2.862
2,099
3.3
.25
8.400
.5
4,961
.4
1.0
.46
4,600
.3
3,055
.3
.7
6.1
.47
.36
3,290
21.960
1,364
17,224
6.8
.37
25,250
1.4
18,588
1.5
8.5
.86
73,100
4.2
61,098
5.1
20.9
.08
16.720
6.2
.19
11.780
36
.50
18.000
30.7
.15
1 5
1.0
.4
2.5
.43
0.75
1.75
1.00
39
1.01
14.0
0.9
56.0
936
.50
.24
16
.21
570 7
.31
46.500
2.7
6,450
7.500
7.000
25.000
39,500
2.3
70.000
2.160
89.600
196.660
4.0
.1
5.1
11.2
1,754.000
100 2
5.726
5.627
8,923
20,276
5.384
4.171
2,151
13,847
Total or average
Uludag
Uganda Nyamalilo
United Kingdom Hemerdon
United States- 1
Grand total or average
'Resource data were obtained from the following sources 1 — Calculated from published dimensional data on ore body; 2-
3 — Data provided by company, government agency, or person familiar with deposit.
'Country total only.
3 Less than 1 million t
'Individual deposit data not provided owing to confidentiality of information See table 3 for deposit names.
20,169
35.372
1,556
55.020
145.569
1.205,945
1.7
1.7
2.9
.1
4.6
12.1
100.1
1. 3
1, 3
1, 3
3
■Published resource estimate available;
Tasmania (60 pet of the total), and the Mount Carbine
wolframite mine in northern Queensland. The remaining
10 pet is from half a dozen small mines in Tasmania,
Queensland, and the Northern Territory. The five deposits
evaluated (fig. 9) account for 11.0 pet of the contained W0 3
in MEC deposits evaluated.
I
^3^^—
-
/i
1
* f
^ /it
[
ChilO ^^ S /^
'/
*
\) V> J
J / ARGENTINA / /
j \ URUGUAY -r^" y .
300 1000
1 1 \^
9col«, IK
LEGEND
A 44 Deposit listed in toble 4
Figure 11. — Location map, South American
deposits.
Figure 10.— Location map, European deposits.
400,000 t '250,000 t by open pit), for a total of 6,400 t of
25 pet WO, concentrate.
The deposits occur in a series of regionally metamor-
phosed rocks of Paleozoic age, especially within volcanic
tuffs of alkaline to intermediate composition. The scheelite
depofT is divided into Ostfeld (eastern) and Westfeld
'western' ore zones. Minable scheelite is concentrated in
stratiform, lense-shaped ore bodies having an average width
of 100 to 150 m, and several hundreds of meters in length.
Maximum thicknesses of 20 m occur in the central portions
of the lenses. The ore bodies dip at 25° to 55° to the north-
west . The deposit is 2,000 m long by 1,300 m vertical depth.
In the Westfeld, seven ore bodies are known, all dipping
40 to 50 to the north. Demonstrated resources as of
January 1983 have been estimated to total 4.5 million t
averaging 0.50 pet W0 3 .
Bolivia
Bolivia has numerous small tungsten mines, from which
an estimated 6.4 million lb of W0 3 was produced in 1982
t9>. Bolivian deposits evaluated, all producers, include Bolsa
Negra. Chambillaya, Chicote Grande, Chojlla, Enramada,
Kami. Pueblo Viejo, Tasna, and Viloco (fig. 11). A particular
problem in defining Bolivian resources is that many of the
deposits are poorly explored, with drilling done only to block
out reserves to be mined in the near future. Hence, the re-
sources estimated in this evaluation, which total 3.0 pet of
the contained WOj in the MEC deposits evaluated, may sub-
stantially understate the country's tungsten endowment.
Bolsa Negra is an underground mine, leased to a
cooperative numbering nearly 400 workers, which has
operated the mine since 1965. Current annual ore produc-
tion is 60.000 t and there has been very little progress in
mechanizing the mine or in controlling production tonnages
and grades.
i occurs as lenticular-shaped mantos. dip
ping at 20°, within a hornfelsic unit. There are approx-
imately 20 known mantos contained in an area 60 m wide
and 800 m long. Currently, three mantos are in production
on each of four levels, and continuation below the lowest
level is considered most likely. Lateral limits of the
mineralized structures have not been determined, and vir-
tually no exploration or development work has been done
in recent years beyond that necessary to maintain produc-
tion. Total demonstrated resources have been reported to
be 500,000 t averaging 1.04 pet W0 3 {14, p. 8).
Production from Chambillaya began in 1912 on a small
scale. The property was acquired in 1973 by International
Mining Co. which has initiated a program for more
systematic exploitation of the deposit.
The mineralized veins that make up the Chambillaya
deposit are essentially vertical and vary in width from 1
to 80 cm, averaging 30 cm. Lengths vary from 30 to 50 m,
with vertical dimensions usually greater than the horizon-
tal. The tungsten mineral is ferberite. In order to meet
acceptable market specifications, the arsenic and sulfur that
are intimately associated with the ferberite must be re-
moved from the tungsten concentrate.
One of the four sections of the mine was in the process
of being evaluated at the time of this analysis and the
results were not known. Total in situ demonstrated
resources as of January 1983 were estimated to total
500,000 t at 0.58 pet WO a .
At the time of this analysis, Chicote Grande was in the
exploration stage; production was expected to reach full
daily capacity of 1,000 t as an underground operation by
1985. Small-scale surface mining of tungsten has occurred
for at least 40 yr, but the recent work represents the first
serious attempt to exploit the deposit on a commercial basis.
More than 60 veins with widths in excess of 10 cm have
been mapped in the 1.8-km main exploration crosscut. The
only mineral of current economic interest is wolframite,
which occurs as isolated crystals ranging in size from a few
millimeters to 5 cm long in a gangue of quartz, pyrite, and
14
arsenopyrite. Apparently, neither lateral nor vertical extent
of mineralization has yet been fully defined, but some of
the main veins outcrop for several hundred meters
distributed in a circular area 2 km in diameter. The deposit
was reported to contain in excess of 4 million t grading 0.8
pet W0 3 (15). For this study, 2.4 million t was assumed to
be demonstrated.
The Chojlla and Enramada Mines exploit separate
portions of the same mineralized structure. Both are owned
and operated by International Mining Co., an established
Bolivian entity. Because each mine is operated as a separate
and distinct operation, they have been evaluated separately
for this study. Since International's acquisition of both prop-
erties in 1973, both operations have been extensively mod-
ernized and mechanized.
The mineralized zone at Chojlla consists of more than
30 parallel veins over an area of 450 m by 1,400 m as deter-
mined at the Carmen haulage adit, the current lower limit
of exploration and development. The veins have a
longitudinal en echelon arrangement with horizontal lenses
varying from 30 to 250 m long. Vertical lenses vary from
20 to 100 m high. Depth of the mineralization is at least
400 m (to the Carmen level), but actual extent has not been
established. Demonstrated resources were reported to total
only 800,000 t at 0.4 pet W0 3 (14, p. 8); however, according
to available dimensional data, this figure appears to
significantly understate the resource, and a figure of 2.8
million t was used for this study.
Production at Enramada is by open stope from more
than 20 veins that vary in width from 1 cm to 1 m (average
70 cm). The veins consist mostly of quartz, with wolframite,
arsenopyrite, pyrite, sphalerite, pyrrhotite, tourmaline,
muscovite, fluorite, and minor amounts of cassiterite.
Scheelite is also found sporadically. Mineralization is con-
fined to the veins, and much of the wolframite occurs in
crystals up to several centimeters in length. The mineral-
ized zone is approximately 800 m long by 30 m wide with
a depth of 300 m at the Liliana haulage adit. In 1979, in
situ demonstrated resources were reported to total 700,000
t averaging 0.8 pet W0 3 (14, p. 8). The potential for addi-
tional resources apparently is very high, probably at least
sufficient to last another 20 yr at the expected 1985 design
capacity of 185,000 t/yr.
Kami is a major underground producer of Bolivian
tungsten concentrate, despite the fact that the deposit is
reported to be exploited in an inefficient and disorganized
manner, with little technical or managerial control. It has
been owned by Comibol since 1952, but has been leased to
a mining cooperative since 1965. Mining is by very
primitive manual methods, with hand sorting of broken ore
and simple concentration devices. Current annual produc-
tion of ore is on the order of 114,000 t.
The deposit has separate tin- and tungsten-rich zones,
with tungsten concentrated in a hornfels unit covering an
area of 21.7 km 2 . Tin mineralization is in a distinct zone
bordering the periphery of the tungsten zone. Each zone is
mined separately by the cooperative. Only the tungsten-rich
section was evaluated for this study. Within the tungsten
zone, production is from two principal vein systems. In-
dividual veins average about 30 cm in width. Depth of
mineralization has not been accurately determined, but ex-
tends to at least 850 m.
Officially reported demonstrated resources as of 1979
were 170,000 1 at 0.86 pet W0 3 (14, p. 8); however, the mine
is still producing, and, for purposes of this study, it has been
assumed that there is sufficient ore to support the current
level of production through at least 1987. Wolframite is the
principal ore mineral. Sulfide content generally increases
with depth. As future production extends to depth, it will
probably be necessary to use more sophisticated processing
techniques to process ore with higher arsenic and sulphur
content.
Production at Pueblo Viejo commenced in 1914 with
small-scale surface exploitation of outcropping veins.
Underground mining by open stope methods through five
adits began about 1970. Average annual ore production has
increased from about 5,200 t in the early 1970's to nearly
30,000 t in 1981. Under a recently completed program of
mine development and improvement to the mill, production
is expected to increase to around 36,000 t annually.
Mineralization at Pueblo Viejo occurs in fractures
within a dacite intrusive measuring 15 km by 8 km. The
mineralized vien system is approximately 1,000 m long and
200 m wide. Veins vary in width between 25 and 30 cm,
but all are mined to a minimum width of 1 m. Vertical ex-
tent of the vein system has not been defined, but recent
development work on the lowest of three working levels has
verified that ore extends to that level. On this basis,
demonstrated in situ resources have been verified to be ap-
proximately 100,000 t, sufficient to continue production
until 1986. Of notable significance is the fact that the veins
at the surface appear to be narrower and of lower grade than
deeper in the mine, a factor that favors exploration at
depth.
Prior to 1979, Tasna was primarily a bismuth-copper
mine, with only 30 to 40 t of tungsten concentrate produced
annually. However, with the collapse of bismuth prices and
rehabilitation of the wolfram section of the deposit in 1976,
it has become a major Bolivian tungsten producer. Current
annual production is approximately 115,000 t of ore. There
are no known plans for expansion or improvement of the
operation to increase reserves beyond those that presently
are known and can only last through the 1980's.
The total mineralized area around Tasna covers 30 km 2 ,
with separate vein systems rich in tin, bismuth-copper, and
tungsten. Only tungsten is currently produced from 19
stopes on six veins up to 50 cm wide, 300 m long, and 250
m deep. Half of total production is from stoping on wider
(at least 50 cm) veins, the remainder from miniblock caving
on 40- by 60-m blocks with heights of 30 to 40 m. Block cav-
ing is used on relatively low grade (less than 0.5 pet W0 3 )
stockworklike structures. All ore is floated to remove sulfide
minerals.
Known in situ resources in the tungsten section total
only about 400,000 t at 0.84 pet W0 3 , and there are little
data from which to verify additional resources at lower
levels of confidence. A crosscut driven on one working level
of the mine to explore the stockwork mineralization in-
tersected a number of thin veins of a grade substantially
below the present cutoff level.
Viloco is an underground mine with separate tin and
tungsten zones, resulting in two separate and distinct min-
ing operations. Comibol owns the property, but the tungsten
section is worked by a group of contractors who receive pay-
ment only for final concentrate they deliver to Comibol. A
few thousand tons is mined annually by simple, primitive
methods. The deposit contains principally tin mineraliza-
tion, but wolframite veins occur in what is known as the
15
Tras Cuarenta section located in close proximity to a
granitic batholith. Host rocks are Lower Devonian quart-
zite and slate. Two separate groups of wolframite veins, one
consisting of T veins, the other 12, comprise the known
resource. Veins dip at 60 to 75 \ with widths varying from
a few centimeters up to 1.5 m. averaging 60 cm. They con-
tain mostly quartz, with some arsenopyrite and'pvnte. and
minor chalcopyrite. sphalerite, and jamesoiute. Only
wolframite and small quantities of scheelite are recovered.
The full extent of mineralization has not been
determined, since exploration and development work has
been very limited. Horizontal development of the vein
system extends to a length of 100 m and a depth of 150 m.
Based on the present degree of knowledge, the tungsten sec
tion of Viloco has onlj 40.000 t of demonstrated resources.
averaging 1.50 pet WO, ; however, the potential
for additional resources is considered to be good.
Brazil
Brazil is an important producer of tungsten, with
estimated 19S2 output of 3.300 lb of W0 3 (9i. Properties in-
cluded in this analysis are Brejui. Barra Verde, Boca de
Lage. and Zangarelhas (fig. ID. all of which are contiguous
sections of a single large tungsten deposit located 6 km from
Currais Novos Together they contain 1.5 pet of total con-
tained \V0 3 in the MEC deposits evaluated.
From the original outcrop at Brejui Mine, which has
been in operation since 1943. the ore-bearing unit occurs
in a laterally i I set of uniformly plunging folds, the
>f which dip at 10 to 15 . and extend about 3.6 km
over a vertical range of 760 m. The ore zone is
approximately 150 m wide and is comprised of two car-
bonate beds averaging 20 m thick separated by 20 to 60 m
of quartz biotite gneiss. The carbonates occur w ithin a thick
sequence of interbedded schist and gneiss. Scheelite is the
only economic mineral; although molybdenum is present,
it is not recovered.
Brejui is an underground mine. There was an open pit
section that operated sporadically as recently as 1980. Barra
Verde, the adjacent lateral extension of Brejui, has been
producing an average of 180.000 1 annually since 1955. Boca
de Lage has produced nearly 100,000 t/yr since 1977 and
Zangarelhas is currently being explored, with production
assumed for 19*7 for purposes of this study. The facilities
at Brejui and Barra Verde are owned by separate companies
and operated independently. Boca de Lage and Zangarelhas
are both owned by a subsidiary of Union Carbide; therefore,
it has been assumed for purposes of this study that assumed
annual output of 105.000 t of Zangarelhas ore would be
processed at the Boca de Lage concentrator, which would
be expanded to accommodate the increased production.
Total demonstrated resources for the entire deposit (all
four properties) are less than 5 million t at a weighted-
average grade of approximately 0.5 pet W0 3 .
Burma
Most of Burma's tungsten production is derived as a
b> product of alluvial tin mining by a large number of small
mines located along the 1 < r, not
all production is reported and a considerable amount is
probably illegally transported out of 'he country. Mawchi
ifig. 1 2 1. located in K;i robably ai I for a
ficant portion of Burr ion of 1.9
million
LEGEND
A 53 Deposit listed in table <»
Figure 12.— Location map, southeast
Asian deposits.
included in this study, with 0.2 pet of the total contained
W0 3 in the MEC deposits evaluated.
Prior to World War II, Mawchi was the second largest
tungsten mine in the world, but the mine was effectively
dost roved by Japanese occupation' forces during the war
with a program of high-grading the deposit. Despite
technical and financial assistance from the U.S.S.R., the
mine has not reopened on a comparable commercial scale.
Presently, mining at Mawchi by tribute operators is
restricted to 1-m-thick veins in granites, the distance
between veins averaging 3 m. The contact of the granites
with country rocks produced a contact metamorphic (tac-
tite) deposit in limestones, which has been mined out.
Mineralization in the veins now being worked consists of
scheelite, wolframite, cassiterite, and arsenopyrite in a
quartz matrix that tends to be richest at the edges of the
veins near their contact with the granite.
Apparently very little systematic exploration has been
conducted at Mawchi since prior to World War II and none
currently is planned; thus, information regarding extent
or magnitude of resources is lacking. As of January 1983,
in situ reserves are approximately 0.6 million t grading 0.5
pet W0 3 and 0.9 pet SnO.,.
Canada
Canada produced an estimated 8.3 million lb of WO:, in
1982 (9), or 7 pet of the world total, and 15 pet of produc-
tion from MEC's. Four Canadian deposits were evaluated
for this study. They include Cantung in the Northwest Ter-
ritories, Mactung on the Northwest Territories border,
Logtung in the Yukon, and Mount Pleasant in New
Brunswick ifig. 13). Together they contain 48.4 pet of con-
tained WO, in the MEC deposits evaluated for this study.
Of the four, only Cantung has produced. It. is now
temporarily closed down, awaiting more favorable market
conditions.
Cantung originated as an open-pit operation in 1962,
but underground development commenced in 1972 as a
room-and-pillar operation. The major geological structure
in the mine area is a north-northwost 1 rending sync-lino
Mineralized metamorphic- aur< ing from a few to
ind meters v\ ido on- found around granitic in-
mm- intruding a series of Precambrian to Dpp< r Cam
brianargil andcarbo diments. The intrusives
are probably related to large Cretaceou batholith"
16
LEGEND
A 34 Deposit listed in table 4
Figure 13.— Location map, Canadian deposits.
occurring southwest of the mine area. Only tungsten ore
is mined. The scheelite occurs with minor chalcopyrite and
massive pyhrrotite in quartz-calcite veinlets. Proven
minable reserves at Cantung were reported to be 3 million
t grading 1.32 pet W0 3 at the end of 1981 (16).
The Logtung property, under option to AMAX Minerals
Exploration, is located midway between Watson Lake and
Whitehorse in the Yukon. In terms of contained tungsten,
it is the second largest MEC deposit evaluated for this study,
with defined geological resources totaling 163 million t
grading 0.12 pet W0 3 and 0.052 pet MoS 2 (17, p. 73).
The Logtung area is underlain by Mississippian
sediments, which have been largely altered to hornfels and
tactites by intrusions of Jurassic or Cretaceous age. The
predominant skarn is light green and siliceous with poorly
to well developed bedding. Less common pyroxene and
garnet skarn occurs in narrow beds, often with abundant
disseminated scheelite and powellite. Tungsten, and
molybdenum mineralization occurs within three different
systems. A stockwork of quartz veins and fractures centered ,
upon a large felsic dike contains 90 pet of the total
molybdenum and 75 pet of the total tungsten. The higher
grade zone measures approximately 700 m in diameter and
extends to a depth of over 300 m. Quartz veinlets up to 5
mm thick contain fine-grained molybdenite, scheelite, and
powellite with accessory pyrite, pyrrhotite, sphalerite,
garnet, fluorite, and beryl. The mineralization is concen-
trically zoned in the stockwork with a core of molybdenite,
minor scheelite, and powellite centered on the porphyry
dike, an intermediate zone of scheelite, and an outer zone
of minor sphalerite and scheelite. Ten percent of the total
tungsten occurs as disseminated scheelite and powellite in
skarn beds. Large quartz veins contain approximately 15
pet of the total tungsten and 10 pet of the total molybdenum
(17).
As of May 1982, the project was still in the development
stage. AMAX has completed engineering and mining
simulation studies, metallurgical testing, cost estimates,
and financial analyses. For purposes of this evaluation,
Logtung has been modeled to come into production by the
end of this decade.
Mactung is located along the Yukon and Northwest
Territories border. There were plans to bring it into pro-
duction by the mid-1980's as a room-and-pillar operation
of 350,000-t annnual capacity. As at Cantung, metalliza-
tion occurs within carbonate sediments in contact with
Cretaceous intrusives. In fact, mineralized units at Mactung
are correlative with those at Cantung although at Mactung
the units are gently dipping and not generally as severely
deformed as they are in the Cantung area. The scheelite
at Mactung is generally finer grained than that at Cantung.
The Mactung ore body is composed of a lower ore zone of
one horizon and an upper ore zone of three horizons. The
two zones are separated by 78 m of barren hornfels.
AMAX officials estimated reserves to be 57 million t
grading 0.96 pet W0 3 , making Mactung the largest deposit
(in terms of contained W0 3 ) evaluated in this study. These
reserves include 4.5 million t in the lower zone, which could
be mined by underground methods. Another option being
considered is to initially mine the upper zone, which con-
tains 7.3 million t of minable ore averaging 1.41 pet W0 3 ,
by open pit methods (18, p. 2). For purposes of this study,
the mine was evaluated as an underground operation with
initial "high grading" of approximately 15 million t of ore
averaging 1.37 pet W0 3 .
At Mount Pleasant, mineralization accompanied brec-
ciation and fracturing of a silicified feldspar-quartz por-
phyry referred to as the Mount Pleasant Volcanics. The por-
phyry is believed to be Mississippian in age, and locally
overlies a series of argillites (Charlotte Group) and granites
(St. George). The extent of silicification is believed to be ap-
proximately 1,800 by 900 m, generally affecting the por-
phyry with only minor alteration of the sediments to the
west. Extensive exploration has yet to be performed in this
area. Mineralization in the silicified portion of the porphyry
ranges from sparse disseminations to massive patches,
lenses, and fracture fillings. Tungsten occurs as both
wolframite and ferberite. Molybdenum sulfide would be
recovered along with tungsten products.
Two areas of molybdenum-tungsten mineralization are
known to occur at Mount Pleasant, the North Zone and the
Fire Tower Zone. The latter consists of three separate
molybdenum-tungsten bodies called Fire Tower North, Fire
Tower West, and Fire Tower South. Mineralization in the
Fire Tower South area has been intersected in a few holes
and is a promising exploration target. Undiluted
demonstrated geological ore reserves for the Fire Tower
North and West were reported to be 9.135 million t of 0.393
pet W0 3 and 0.202 pet MoS 2 . The North Zone contains four
poorly delineated molybdenum-tungsten zones, a bismuth
zone, a deep tin zone, and six near-surface tin-base metal
bodies. Possible and probable reserves were given as 11.5
million t averaging 0.11 pet Sn, 0.24 pet W0 3 , and 0.10 pet
MoS 2 , as well as 9 million t of 0.1 pet Bi (19).
Wolframite and molybdenite can be satisfactorily
recovered from the Mount Pleasant ore; however, it is ex-
pected that recovery of cassiterite and bismuth will be dif-
ficult (20, p. 113). For this reason, this property has been
evaluated under the assumption that only wolframite and
molybdenite will be recovered.
France
France, although not a major world tungsten producer,
has two deposits, Salau and Montredon (fig. 10), that con-
tain 25,200 t of contained W0 3 at the demonstrated level,
or 1.4 pet of the total in the MEC deposits evaluated.
The Montredon-Labessonie tungsten district, in which
the Montredon Mine is located, contains approximately
30,000 1 of W0 3 of which 800 1 was exploited between 1955
and 1960 (21). The district occurs within Middle Cambrian
micashists in a dome structure underlain by an orthogneiss
massif. The mineralized vein field consists of two groups
of veins, each consisting of thick (0.3 to 2.0 m) and thin (less
than 0.3 m) veins. The thiclt veins are more regular_than
17
the thin veins. The field strikes northeast and dips 60°
south. Wolframite is irregularly distributed and is
associated with minor amounts of cassiterite, fluorite, beryl,
and 0.01 pet sulfides, of which pyrite is the most abundant.
The vein field in the Montredon Mine area has been ex-
plored by mine workings over a length of 600 m and a width
of 300 m. Total demonstrated in situ resources at the Mon-
tredon Mine are 2 million t averaging 0.63 pet W0 3 .
The Salau Mine has been in production since 1971. Mon-
tredon, a past producer, is being evaluated by property
owners as a possible open-pit operation, scheduled to recom-
mence production in 1984. For purposes of this evaluation,
it has been assumed that production would begin in that
year.
Mineralization at Salau occurs as three types: skarn bar-
ren of sulfides characterized by low grades (0.2 to 0.4 pet
WOji; sulfide-rich skarns of medium grade (averaging 0.9
pet W0 3 >; and somewhat massive pyrrhotite in limestone
intercalated within granite slabs with high grade (2 to 10
pet WO,) (22). The ore zone occurs as a column-shaped struc-
ture adjacent to granite between 1,320 and 1,600 m eleva-
tion, with a horizontal length of 220 m and a width of 50
m. The ore body is extremely irregular and the mineraliza-
tion discontinuous. The ore is dispersed and broken into
several overlapping but more or less separate lenses, so that
each lens can be considered as an independent ore body.
This also renders resource evaluation extremely difficult.
The demonstrated resource as of January 1983 was 0.9
million t containing 1.4 pet W0 3 .
Mexico
The three tungsten-bearing Mexican deposits evaluated
for this study are Baviacora, Los Verdes, and San Alberto
'fig. 14). All are located in the State of Sonora and contain
1.2 pet of total contained W0 3 in the MEC deposits
evaluated.
The general geology of the Mexican tungsten district
can be characterized as consisting of a thick sequence of
volcanics overlying a sedimentary and metamorphic base-
ment. The volcanic sequence is several hundred meters
thick and is comprised of flows, tuffs, and breccias that
originated from a series of north-northwest trending faults.
The volcanics were intruded by acidic plutons emplaced dur-
ing the Laramide Orogeny. Differential erosion has resulted
in a series of ranges consisting of volcanic plugs and intru-
sions flanking valleys floored with lava flows and sedimen-
tary debris. Site-specific geology for the Sonoran deposits
is difficult to obtain; however, it is known that tungsten,
copper, and molybdenum mineralization at Los Verdes is
associated with a granodiorite porphyry, while Baviacora
and San Alberto are tactite deposits. Scheelite is the
primary tungsten mineral at Baviacora and San Alberto.
Wolframite is recovered at Los Verdes.
Baviacora and San Alberto are small open pit operations
with mining labor perfomed by "gambusinos," small groups
of local laborers. Annual ore production totals only about
30,000 t for each deposit, with very low productivity. For
Los Verdes, which is a pilot operation producing only a few
tens of metric tons of concentrate annually, it was assumed
for purposes of this study that mining will initially be done
with gambusinos until the late 1980's, when more
mechanized operations would take over and production
would be increased to 300,000 t/yr. Very little information
is available concerning the Los Verdes operation; evidently,
though, there are problems in attempting to treat the ore
because of the fineness of the tungsten particles. For the
San Alberto evaluation, it was assumed that annual pro-
duction could increase to 200,000 t by 1985.
As with geological data, resource information is
extremely difficult to obtain for the Mexican properties, and
confidential resource data for individual properties cannot
be disclosed. Total demonstrated resources for the three
deposits are estimated to be 4.7 million t at a weighted-
average grade of 0.45 pet W0 3 , of which approximately half
is at San Alberto.
Namibia
Two Namibian properties, Brandberg West and
Krantzberg (fig. 15), were included in this study. Together
they contain 0.5 pet of total contained W0 3 in the MEC
deposits evaluated. Both are past producers, with dubious
chances for resumption of production. For purposes of this
evaluation, it has been assumed that production at both
properties could begin in 1986 at an annual capacity of
105,000 t.
Brandberg West is a hydrothermal wolframite-bearing
vein deposit, with veins ranging between 1 and 3 m wide
and 100 to 300 m long, dipping at 65°. Remaining reserves
are estimated to total 2.4 million t grading 0.20 pet W0 3 .
Owing to poor mining methods, aggravated by rising costs
and low metal prices, the mine closed in 1979. A large
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African deposits.
18
amount of new development work would be necessary in
order to resume production.
The Krantzberg deposit consists* of lenses of greisen
material with dimensions of up to 1Q0 m long by 100 m
wide. The lenses, mainly horizontal, are scattered and dif-
ficult to prospect. Wolframite was the dominant ore mineral.
Total remaining demonstrated resources are 0.9 million t
grading 0.40 pet W0 3 .
Peru
Pasto Bueno (fig. ID produces 660 t annually of high-
grade huebnerite concentrate, plus byproduct lead, zinc, cop-
per, and silver, from the treatment of 150,000 t of ore. Pasto
Bueno is a group of three underground operations, Consuzo,
Huaura, and Huayllapon, all of which are owned by a
private Peruvian company and are located in the District
of Pampos, Pallasca Province, Ancash Department. The
mines are located 0.2, 15, and 17 km, respectively, from the
concentrator at Consuzo. The Pasto Bueno deposit accounts
for 0.3 pet of contained W0 2 in the MEC deposits evaluated.
The geology of the Pasto Bueno area is characterized
by a Tertiary quartz monzonite stock that has intruded a
sequence of Upper Jurassic to Lower Cretaceous slate,
limestone, and quartzite. The mining district contains more
than 25 mineralized veins located partly in the monzonite
and partly within the sediments. Four of the veins are of
major economic significance. There have been two major
episodes of mineralization, of which the second produced
the important economic deposits. Typically, the district
displays a vertical mineralogical zonation, characterized by
increasing sulfide content with depth.
In situ resources as of 1983 were estimated to total ap-
proximately 1 million t containing 0.46 pet W0 3 and 0.44
pet Cu.
Portugal
Estimated 1982 W0 3 production from Portugal was 3.8
million lb (9). The two Portuguese properties evaluated for
this study, Panasquiera and Borralha (fig. 10), are owned
by the Beralt group and contain 1.4 pet of total W0 3 con-
tained in the MEC deposits evaluated.
The Borralha deposit is situated within the same
geologic complex as Panasqueira. Maximum concentrate
production in recent years was 370 t in 1975. Sufficient
resources to last through 1990 at the planned rate of 360
t of concentrate per year have been indicated during
development to the 160-m level. The veins are known to
extend to greater depths but as of 1979 had not been drilled
below 160 m. The mineralization is composed of 80 pet
wolframite and 20 pet scheelite {23). Demonstrated reserves
based on development drilling are 0.7 million t grading 0.47
pet W0 3 .
Panasquiera is the single most important tungsten pro-
ducer in western Europe, with over 2,100 t of high-grade
wolframite concentrate annually, as well as tin and copper,
from approximately 520,000 t of ore. Mining has taken place
since at least the 1890's, and there is evidence that the
deposit was worked by the Romans and Moors. Owing to
labor strikes in 1981, the mine's output was severely
reduced and planned production was not reached in 1982
(24, p. 490).
The main mineralized zone is a complex vein system in
phyllite within the contact zone of a granite complex that
is located over most of northern Portugal and forms a tin-
tungsten district that extends into Spain. The late Precam-
brian phyllite has intercalations of graywacke and fine-
grained quartzite, and lacks distinct bedding but has a well
developed system of subhorizontal joints, which has
controlled the emplacement of mineralization.
The main ore-producing zone consists of overlapping
subparallel quartz veins that dip 8° to 10°; the zone is 70
to 80 m thick and has been worked over a strike length of
500 to 1,000 m and a dip of more than 2,000 rn (25); however,
present proven depth is estimated to be 150 m. Assuming
50 pet waste material, there is on the order of 6.1 million
t of in situ resources at an average grade of 0.36 pet W0 3 .
Republic of Korea
The Sangdong Mine in the Republic of Korea is a major
world producer of scheelite in the form APT, artificial
scheelite, high-grade natural scheelite, and tungsten metal,
oxide, and carbide powder. The mine also produces
byproduct bismuth and molybdenum. Sangdong was respon-
sible for nearly all of the Republic of Korea's estimated 6.3
million lb of W0 3 in 1982 (9) and contains 4.2 pet of the con-
tained W0 3 in the MEC deposits evaluated. Sangdong is
operated by Korea Tungsten Mining Co. Ltd., a 100-pct-
government-owned entity.
The largest percentage of ore-grade mineralization at
Sangdong occurs in a single stratabound body, the Main
Vein, 3.5 to 5 m thick, which is located in the folded quartz-
rich Myobong Slate of Early Cambrian age. The mineralized
portion has been traced for over 1,500 m along both strike
and dip. It is located on the gently dipping southern limb
of an overturned west-nortwest trending asymmetrical
syncline.
The fine-grained, disseminated scheelite of the Main
Vein is associated with several distinct silicate mineral
assemblages, which exhibit a well-defined bilateral zona-
tion in the plane of the ore horizon. Ore grades decrease
markedly from the inner mica-rich zone (average 1.5 to 2.5
pet W0 3 ), through the hornblendic intermediate zone (0.3
to 1.5 pet) to the diopside-garnet zone (less than 0.5 pet) (26).
Demonstrated in situ resources are approximately 8.5
million t averaging nearly 0.86 pet W0 3 and 0.13 pet com-
bined bismuth and molybdenum.
Spain
Three Spanish properties, all producers, were evaluated
for this study: Barruecopardo, La Parilla, and Santa Comba
(fig. 10). Together they contain 2.7 pet of total contained
W0 3 in the MEC deposits evaluated.
Barruecopardo is owned by Coto Minero Merladet, a
100-pct-family-owned company that controls the leases
covering a large percentage of the Barruecopardo mining
district. The district has been known about since the early
1900's but mining activities were negligible until 1940.
Mining is by open pit method. Scheelite, the most im-
portant tungsten mineral in the deposit, and wolframite in
many veinlets are located within a medium- to coarse-
grained leucogranite. The deposit is relatively low grade,
averaging approximately 0.1 pet W0 3 . Thickness of
mineralized veins varies from 0.5 to 15 cm, although they
may exceed 0.5 m. Dimensions of the remaining resources
average 800 m long by 100 m thick by 90 m deep, with an
estimated 20.9 million t grading 0.08 pet W0 3 as of January
1983.
The present open pit mine and mill operation at La Parilla
19
began in 1971. Scheelite is the primary ore mineral and
is mined from a series of mineralized veins over an area
of 150 m by 700 m. to a confirmed depth of 150 m. As of
January 19S3. demonstrated in situ resources are estimated
to total 6.2 million t averaging 0.19 pet WO,, and 0.03 pet Sn.
Mining at Santa Coniba began in 1943. lasted until
1963. and recommenced in 1968 under the ownership of
Compania de Minera Santa Comba. In 1980. Coparex
Miner., became the owner-operator and the mine wont
through a recent expansion to extract S00 t d by 1983.
Wolframite and cassiterite are recovered from seven veins
with a thickness varying from 3 to 50 cm each. The vein
system outcrops over an area of 15 km 2 and dips at 75°.
Mineralization is highly erratic.
Demonstrated resources are on the order of 3.6 million
t grading approximately 0.50 pet W0 3 .
Sweden
Yxs E fig. 10> was exploited for its copper content
at least as early as the 18th century, and after the deposit
found to contain scheelite during World War I. it
developed into a tungsten mine from the mid-1930's through
1963. In 1972. it recommenced production and was taken
over by Luossavaara Kiirunavaara AB iLKABi in 1974. The
mine is the only major tungsten producer in Sweden, with
650 t of concentrate produced annually. The deposit ac-
counts for 0.4 pet of contained WO ;) in the MEC deposits
evaluated.
The Bergslagen area, in which Yxsjoberg is located, is
characterized by a series of altered Precambrian (age— 1.8
billion yr) volcanic and sedimentary layers. Regional tec-
tonism convened the acid volcanics to coarse-grained "lep-
tites." and most of the limestone was recrystallized, with
the more impure carbonates altered to skarn. Subsequent
erosion was followed by deposition of pelites and, later, two
phases of granitic intrusions, followed by intrusions of basic
dikes.
The tungsten deposit is comprised of three ore bodies,
Kvarnasen. Vanergruvan, and Finngruvan, all of which
were originally one limestone layer that was folded into a
syncline and anticline with an axial dip of 45° east.
Scheelite is irregularly distributed in the ore bodies, with
Vanergruvan containing the richest concentrations. The
three bodies also vary in size and configuration, with
demonstrated resources totaling approximately 1.5 million
p. 367 1 grading 0.43 pet W0 3 (28, p. 520).
Thailand
Thailands first tungsten mining operations began dur-
ing World War II in Mae Sarieng Province near the
Burmese border. Many of the original mines continue to
ite sporadically. The discovery of two major deposits,
Doi Mok in northern Thailand and Khao Soon in the south
(fig. 12), in the early 1970's resulted in the production of
5 t of concentrate in 1975. when Thailand became th<-
second largest producer among MEC's '29. p. 1.72). Owing
to the unstable local political situation, however, produc-
tion from both mines has been interrupted repeatedly since
then. Following discovery of the Doi Ngoem 'fig. 12)
ferbente deposit in 1977, the chaotic political conditions in
the local mining area were repeated, and order has yet to
be fully restored.
umated production of WO, from Thailand in 1982
totaled nearly 2 8 mii. approximately 2 pet of the
world total (9). The largest individual producer was the Doi
Ngoem field, which accounted for one-fourth of Thai pro-
duction. Substantial amounts of tungsten are produced as
a byproduct of tin mining. For example, in 1981, the Nok
Hoog Mine produced 333,000 lb of W0 3 contained in con-
centrate. The three deposits evaluated account for 2.3 pet
of total contained W0 3 in the MEC deposits evaluated.
The ferberite ore at Doi Ngoem occurs in quartz veins
in metasedimentary tuffaceous sandstone and chert in con-
tact with an underlying biotite-rich granite of Mesozoic age.
At least three parallel veins, all bearing ferberite in
crystalline vugs and disseminations, constitute the ore body.
The major vein averages 20 m in width and extends for a
strike length of approximately 1,500 m (where exposed at
the surface). None of the veins has been traced at depth,
and geological information is difficult to obtain. A spur of
the main vein has been dislocated by a fault, suggesting
a depth of at least 60 m. Based on this information, the
major vein may contain up to 2.5 million t of ore grading
between 1.5 and 2 pet W0 3 . However, only 0.4 million t
grading 1.75 pet W0 3 is considered to be minable given the
current small scale surface operation, which produces 9,000
t of ore annually.
Doi Mok is a tactite deposit containing coarsely
crystalline scheelite, along with arsenopyrite and other
minor sulfides of no economic significance. There are two
areas of mineralization, one a 20-m-wide zone within a
granite close to its contact with overlying sediments, the
other within a limestone unit. The ore body has not been
explored at depth and only 1 million t is estimated to be
in the demonstrated category, grading 0.75 pet W0 3 .
Given the unstable political situation at Doi Mok,
possibilities for future development, mechanization, or ex-
pansion are highly speculative; however, it is possible that
the mine could become a viable operation by 1990, and for
this study it has been projected that production on a
relatively small scale (60,000 t/yr) will have begun by 1990.
Khao Soon is possibly the largest tungsten deposit in
Thailand. Based on general geological characteristics of the
deposit, it could contain 10 million t averaging 1 pet W0 3 .
However, as with other Thai deposits, drilling data are
scarce, and demonstrated resources are estimated to be 2.5
million t averaging 1 pet W0 3 .
The deposit was apparently formed by multiphase
deposition of mineralized solutions within fractures and
faults, particularly along the crest of a north-south anticline
caused by intrusion of a biotite-rich granite. Ferberite, often
with associated stibnite, occurs in pockets and small veins
in mudstone, hornfelsic quartzite, and phyllitic shale. The
main fracture system strikes northwest-southeast.
In 1976, the miners made an agreement with the Thai
Government to sell all ore to Siamerican Mining Co., Ltd.,
which holds the lease at Khao Soon. Government police
were stationed at the mine to prevent violence and restore
order. Continued invasions, however, forced the mine to
close in 1979, and it is inactive at the present. For purposes
of this evaluation, it has been assumed that the operation
will have resumed normal (full capacity) production by 1992.
Turkey
Turkish tungsten production is small, with only 250,000
lb of WO, estimated 1982 production (9), but Etibank's
Uludag Mine (fig. 10), the country's only major tungsten
mine, is potentially a more significant world producer than
its current level of production indicates. The deposit ac-
20
counts for 4.0 pet of total contained W0 3 in the MEC
deposits evaluated. The combined open pit and underground
mine and concentrator have a design capacity of 560,000
t/yr; however, it was reported that difficulties were ex-
perienced during commissioning of the mine and concen-
trator early in 1977, and a firm from the Federal Republic
of Germany was brought in for consultation (30, p. 47). Plans
are to convert the plant from gravity to an all-flotation
operation. For this study, it has been projected that full pro-
duction will be reached by 1985.
Uludag ore occurs both in veins in granitic rocks and
as tactite mineralization. Within the granites, veins have
been emplaced along bedding and shear planes. Scheelite
occurs mostly in finely disseminated form concentrated in
brecciated zones within limestones of Mesozoic-Tertiary age.
The scheelite occurs in four zones lying stratigraphically
above each other. The layers are irregular along the bed-
ding plane, and average thickness of the entire ore-bearing
sequence is 200 m, including barren zones between
mineralized layers.
The deposit contains 14 million t of demonstrated
reserves. Average grade was estimated at 0.5 pet W0 3 (30,
p. 47).
Uganda
Nyamalilo (fig. 15) is one of six stratabound tungsten
deposits in the Kigezi District and is the only Ugandan prop-
erty evaluated for this study. It has been operated inter-
mittently for over 20 yr. Maximum production was reached
during the Korean War, at approximately 100 t/d of ore,
but output had dropped to 50 t by the mid-1970's. For this
evaluation, a concentrate production of 300 t/yr by 1986
(105,000 t of ore) by open pit has been assumed.
The main mineralized zone at Nyamalilo consists of
numerous thin quartz veins enclosed by carbonaceous
metasediments. The veins vary from a few centimeters to
more than 1 m thick and may persist for several hundred
meters along the strike. Larger veins lie along the fractures
of enclosing rocks, while small veins follow bedding and
have been folded along with the rocks. Mineralization is
simple, consisting of fractured glassy quartz, patches of
kaolinite, and ferberite present as the variety reinite
(ferberite pseudomorphous after scheelite).
The low average grade (2.5 lb W0 3 per metric ton, or
0.11 pet) (31, p. 101) results in an economically marginal
operation, except during times of high ferrotungsten prices.
For this evaluation, a mineralized area measuring 1,000
by 50 m to a depth of 50 m was assumed, within which a
demonstrated resource of approximately 0.9 million t
grading 0.24 pet W0 3 was estimated.
United Kingdom
Hemerdon (fig. 10) is the largest known tungsten deposit
in the United Kingdom, and accounts for 5.1 pet of total
contained W0 3 in the MEC deposits evaluated. Its existence
has been known for over a century, but several past at-
tempts to exploit the deposit commercially have proven un-
successful. In 1977, a 4-yr exploration and feasibility pro-
gram was begun, and a pilot plant was erected in May 1980.
A final decision whether to bring the project into produc-
tion was pending at the time of this evaluation. For this
analysis, it has been assumed that initial production at a
rate of 1 million t/yr will begin in 1987, reaching full capac-
ity at a rate of 1.9 million t in 1989.
Mineralization at Hemerdon is largely contained within
a dikelike body of granite approximately 650 m long, 150
m wide, and 200 m deep. Country rocks into which the
granite was intruded consist of Devonian metasedimentary
siltstone, mudstone, and altered basic volcanics. The granite
contains a large number of small quartz veins rarely ex-
ceeding a few centimeters in thickness. Three main vein
systems are present, and the overall effect is of a sheeted
vein complex. All of the vein sets carry wolframite, chiefly
as irregularly distributed coarse aggregates of bladed
crystals. Minor quantities of cassiterite are also present.
Major gangue minerals found in the concentrate are
hematite and arsenopyrite, which decrease and increase,
respectively, with depth of the deposit (32, p. 343 1.
Extensive drilling has established a resource of 56
million t averaging 0.16 pet W0 3 and 0.025 pet Sn (16).
United States
Twelve U.S. deposits that do or could produce tungsten
as the primary product were evaluated for this study.
Together, they account for 11.2 pet of total contained W0 3
in the MEC deposits evaluated. Deposits evaluated include
Adamson, Andrew, Atolia Placers, Pine Creek, and
Strawberry in California; Thompson Creek in Idaho; Emer-
son, Indian Springs, Nevada Scheelite, Pilot Mountain, and
Springer in Nevada; and Tungsten Queen in North Carolina
(fig. 14). Not included in the study was the Climax deposit
in Colorado, which, although the world's seventh largest
tungsten producer when at full capacity, was not evaluated
because it produces tungsten as a byproduct of molybdenum
mining. The deposit contains 375 million t of ore (16) at an
average grade of 0.03 pet W0 3 . Also not included was the
Searles Lake brine deposit in California, with an estimated
77,000 t of W0 3 at concentrations that average 0.007 pet
(6, p. 184). Although tungsten is not presently recovered
from the Searles Lake brines, technology exists to produce
it as a byproduct of soda ash operations.
The Andrew Mine currently produces approximately
375 t of over 40 pet W0 3 and 3,400 1 of low grade (1 pet W0 3 )
concentrate annually, from 180,000 t of ore in talus cones
located in the rugged San Gabriel Mountains north of Los
Angeles. The oldest and most abundant rock type in the
area is massive Precambrian augen gneiss characterized
by porphyritic dikes and sills, hornblende lenses, and in-
terfingering schists. Near the head of Cattle Canyon, in
which the lode, talus, and placer deposits covered by the
claims owned by Curtis Tungsten (owner of the Andrew
Mine) are located, the gneiss is underlain and, in some
places, intruded by a Cretaceous quartz diorite. The Triassic
Mt. Lowe granodiorite and migmatite are exposed
southwest of the gneissic unit. All rock types host quartz
monzonite and andesitic dikes in complex crosscutting rela-
tionships. Scheelite was deposited in and along fracture
planes as veinlets, pods, and fine disseminations and is
locally associated with quartz, calcite, and limonite; epidote
and grossularite are rare.
The mineralized lodes average less than 1 m in width,
and are presently traceable over only short distances.
Because insufficient data currently exist to adequately
evaluate the resources contained in the lode and placer
deposits, only the talus cones, which are well exposed and
are amenable to evaluation, have been included as
demonstrated resources for this study.
The Atolia Placers was the only placer deposit evaluated
in this study. The district, in California, was worked for
21
gold as early as the lS90's. Tungsten-bearing veins were
worked during the early 1900s. and placer mining of the
Spud Patch iso named for the occurrence of potato-sized cob-
bles of scheelite 1 took place during the First World War
when tungsten prices were relatively high. The district has
experienced intermittent production since then, and the last
significant known activity was in 1960.
The scheelite and gold placers of Atolia were derived
from the heavily mineralized Randsburg- Atolia area. The
placer channels begin in the Stringer District. Kern County.
5 km northwest of the town of Atolia where the underlying
rocks and alluviu: I and subordinate scheelite.
The channels trend southeast and. near Atolia. contain
relatively high scheelite and lower gold values. The deposits
vary in thickness from 2 to 40 m and are composed mostly
of sand-sized particles and angular fragments up to 5 cm
in size. Three primary channels contain the majority of gold
and scheelite. They include the Atolia-Moore Placer, the
Spud Patch, and the Atolia Rand ior Baltic* Channel.
Small amounts of scheelite were produced from what
is now known as the Emerson Mine as early as 1937, and
the mine has produced continuously since then, except for
the period 1958 through 1977. The scheelite-bearing tac-
tites occur in two nearly parallel zones along the contact
between a domed granitic stock and altered limestones and
hornfels of the Guillemette Formation. The zones are re-
ferred to as the Moody Tactite and Grubstake Tactite, which
are separated by 15 to 20 m of coarsely crystalline mar-
bleized limestone. The Moody Tactite has a surface strike
length of 2,000 m, which increases with depth. Thickness
varies from 5 to 32 m, over a known vertical depth of at
least 500 m. The Grubstake is not persistent, but is known
to exceed 30 m in thickness in some places.
The Indian Springs deposit in the Delano Mountains,
Elko County. NY. is an irregularly shaped body on the
southeast side of an elongate Cretaceous quartz monzonite
stock in contact with Permian calcareous sandstone of the
lower Pequop Formation. The sandstone is cut by numerous
quartz veins forming a stockwork associated with low-grade
tungsten mineralization. Minor tactite deposits, irregularly
distributed along the igneous contact, occur as pods and
lenses associated with quartz stockworks.
Results from 10,668 m of drilling in 149 locations in-
dicated a reserve of 39.5 million t at an average grade of
0.164 pet WO, Included in this are 12.6 million t averag-
ing 0.265 pet \V0 3 i.33k
The Nevada Scheelite deposit w r as discovered in 1930
and was worked for precious metals for a short time, w ith
the first reported production of tungsten in 1937. The mine
has operated nearly continously through the present time.
In the vicinity of the mine, scheelite-bearing tactites
occur in metamorphosed limestone and hornfels at or near
contacts with a small granite intrusive of Late Cretaceous
or Tertiary age, and probably related to the Sierra Nevada
Batholith. The intrusive crops out over an area of 4 km 2 .
The limestone unit is approximately 150 m thick and has
interbedded tuffs, andesites. and basalts. The granite con-
tact is generally sharp and concordant with country rocks.
Relatively large tactite bodies, up to 15 m thick, were
formed along a major fault, while smaller bodies (av<
ing 3.5 m thick* developed where fingers of granite
penetrated the limestone along bedding planes. Tactite
bodies are irregularly shaped where associated with th<-
fault, but tend to be tabular alon^ concordant contacts.
The Pilot Mountain deposits, in Nevada, were
discovered in the 1920s, with first production in 1929, and
sporadic production through the mid-1950's. The last re-
corded production was in 1956. In the late 1970s, the prop-
erty was acquired by Union Carbide, which has recently
completed a detailed exploration program.
Scheelite deposits at Pilot Mountain occur in a series
of metamorphosed limestones of the Liming Formation,
which has been tectonically disturbed by the intrusion of
a granodiorite porphyry. The original mine workings occur
along the granodiorite-limestone contact, where three types
of mineralization are known to exist: ( 1 1 tactite. (2) a quartz-
calcite-scheelite vein, and (3) irregular masses consisting
of quartz, calcite, galena, scheelite, and silver. The largest
tactite body occurs as a shallow dipping ( 10°) bed that ex-
tends 150 m from the contact.
Pine Creek and Adamson are adjacent properties cover-
ing a series of tungsten-bearing bodies in the Bishop
Tungsten District, Inyo County, CA. The Pine Creek mine
and mill are owned by Union Carbide. The Adamson claims
are owned by Panaminas, Inc., which leases them to Union
Carbide, and production is reported as a combined total. The
Pine Creek custom mill also treats concentrates from
several other smaller mines in the region. Tungsten pro-
duction from Pine Creek has been nearly continuous since
1946.
The Bishop deposits occur in a scheelite-bearing garnet-
diopside tactite situated along ' the contact between
Tungsten Hill Quartz Monzonite and limestone and horn-
fels of the Pine Creek roof pendant, which strikes approx-
imately north-south for 11 km. The sediments form the west
limb of a south-plunging syncline. The tactite dips at a con-
sistent 68° to the east over a strike length of several hun-
dred meters. Scheelite is the major ore mineral, but
powellite is also present, , along with molybdenite,
chalcopyrite, bornite, gold, and silver.
The Springer (formerly the Nevada Massachusetts
Mine) scheelite deposit is located on the eastern slope of the
Eugene Mountains, which trend north-northeast for 26 km
near Mill City, NV. Tungsten was discovered in 1914, and
production commenced shortly thereafter, with intermittent
activity since then. The mine's most prosperous period was
during 1950 through 1958, wdien ; as part of the Government
program to build up a strategic stockpile, over 1 million t
of ore was produced. The deposit is now owned jointly by
General Electric and Utah International, under whom pro-
duction resumed in early 1982, but was suspended later that
year.
The tactites of the area occur in metasedimentary rocks
of the Raspberry Formation, Triassic to Jurassic in age.
Locally, the Raspberry is composed of shale and thin-bedded
limestone, and has been intruded by a series of Late
Cretaceous granodiorite stocks. Principal concentrations of
scheelite occur near the margin of at least one of the in-
trusives, known as the Springer Stock. A dozen or more
limestone beds ranging in thickness from less than 0.3 m
to 9 m occur in the mine area. They have been cut by the
northwest trending Stank thrust fault, the major structural
feature of the area. Past and present production is from
three main tungsten-hearing zones northeast of t he fault,
where the Springer Stock is located.
Strawberry is a producing underground mine in Califor-
nia. It was discovered in 1941, and produced nearly con-
tinuously through 1966. After an extensive drilling program
in the early 1970s. Teledyne acquired the property and
imed producl ion in 1978.
The deposit is located iii a sequence of Lower Jurrasic
calc-silicate hornfels and marble occurring as a roof pen-
22
dant surrounded by a Middle Cretaceous granodiorite
pluton. Tactite deposits resulting from contact metasomatic
replacement of marble occur within 100 m of the grandiorite
contact. Two major bodies of tactite occur on opposite sides
of a major anticline plunging 50°. The bodies dip steeply,
and have an average length on the order of 130 m, an
average downdip extension of approximately 75 m, and an
average thickness of 3 to 4 m. The deposit is of relatively
high grade, with a cutoff grade of 1 pet W0 3 (6, p. 181).
The Thompson Creek Mine is located in the Bay Horse
mining district of central Idaho, 3.5 km northwest of the
Cyprus Mines Thompson Creek molybdenum project. The
deposit was discovered in 1953, and has experienced inter-
mittent production through 1977. It was formed by the in-
trusion of the Cretaceous Idaho Batholith into limestone
beds of the Paleozoic Wood River Formation. Two tactite
bodies occur at the contact between the quartz monzonite
of the Batholith and the limestone. Almost all the tungsten
occurs as disseminated scheelite and ferberite, with minor
powellite. The ore bodies extend for less than 200 m in
length, average on the order of 3 to 5 m in thickness, and
dip at 80°. Total known resources are limited, and are suf-
ficient to produce only through the end of the decade from
the 1984 startup date assumed for this study. The poten-
tial for discovery of substantial additional resources is ap-
parently limited.
The Tungsten Queen Mine (formerly the Hamme Mine),
in Vance County, NC, began operating in 1942; it last pro-
duced in 1971. Tungsten occurs in randomly distributed
quartz veins within a schist and granite-gneiss complex. The
mine consists of one main vein (and several smaller veins)
that strike northeast and dip 70° to the east. Ore occurs
as numerous lenses within the veins. Extent of the
mineralized zone is approximately 3,500 m long, nearly 600
m wide, and 10 m thick. However, entire sections of some
veins are mined out. The principal ore mineral is
huebnerite, but some scheelite and minor sulfides also
occur.
Although a small amount of development work would
be needed to reactivate the mine, it was reported that
Ranchers Exploration and Development Corp., the owner,
has decided to write off the $7.7 million investment (18, p.
20). However, for purposes of this evaluation, the operation
has been modeled to begin producing again in 1986 at an
annual mine capacity of 150,000 t.
CENTRALLY PLANNED ECONOMY COUNTRIES
CPEC's contain over 55 pet of the world tungsten
resources in deposits addressed in this report. China and
the U.S.S.R. account for 93 pet of CPEC reserve base as
estimated by the Bureau (9). A total of 38 deposits, 19 each
in the U.S.S.R. and China, were evaluated for their resource
potential. Pertinent information on CPEC deposits
evaluated is shown in table 4. Only tungsten grades are
shown, although many of the deposits do or would produce
byproducts and/or coproducts. Because much of the infor-
mation used to derive the estimates is highly speculative
and incomplete, the resources cannot be considered as
demonstrated.
China
China is the world's largest producer of tungsten, with
estimated 1982 output of 31.5 million lb of WO, (9). Western
observers believe that China could easily produce 20,000
to 25,000 t of concentrate annually with the necessary lead
time, of which 10,000 t could be exported (34).
China is widely known to have the world's largest
resources. One estimate places proven and probable (i.e.,
demonstrated) reserves at 1.2 million t (2.6 billion lb) of
W0 3 , and potential reserves at nearly 2.4 million t (greater
than 5 billion lb) (35, p. 75). National reserves have been
officially reported to be 4 million t of W0 3 , or on the order
of 8.8 billion lb of W0 3 (36, p. 436). The Bureau estimated
China's reserves to be 3.8 billion lb of W0 3 , and total
resources on the order of 10 billion lb (8, p. 983).
Tungsten occurrences in China have been known about
for many years. For example, Xihuashan, perhaps the best
known Chinese deposit, was discovered in 1908. China came
into world prominence in the years preceding the First
World War, when most mining was done using hand labor
and primitive techniques. Modern expansions and relatively
advanced mechanization were not introduced until after the
mines were nationalized in 1949. The first mechanized
tungsten concentrator was erected and brought on stream
jn 1952 at Tajishan in southern Jiangxi Province.
Practically all known Chinese tungsten deposits are
located in the Nanling Range in the southern part of the
country. It is a rugged mountain chain trending southwest-
northeast from southeastern Yunnan Province through
northern Guangxi, northern Guangdong, and southeastern
Hunan, to southern Jiangxi and Fujian Provinces. Complex
folding and fracturing of sediments (contained in what was
originally the Jinning-Caledonian Geosyncline during the
Jinning, Caledonian, Hercynian, Indosinian, and Yensha-
nian tectonic episodes), along with extensive magmatism,
particularly the Yenshanian granitic intrusions, provided
exceptionally favorable conditions for the generation and
emplacement of tungsten deposits. The metallogenic episode
occurred during the Jurassic-Cretaceous period.
Chinese tungsten deposits can be categorized into five
types: quartz vein, skarn, disseminated, stratiform, and
placer. Many of the vein type deposits, currently the most
important economically, are located in Jiangxi Province.
A typical large Jiangxi mine in the Tayu District has hun-
dreds of steep veinlets occurring over a mineralized area
of several square kilometers, with reserves of possibly
100,000 t of W0 3 contained in ore assaying 1.2 pet W0 3 and
0.5 pet Sn. Mining at depths of 100 to 250 m is well
engineered and at least semimechanized, and daily ore pro-
duction is in the 2,000-t range (37). Xihuashan is a typical
Jiangxi hydrothermal vein deposit, in which quartz veins
and stringers have replaced or filled fractures in granite
over a 4.5-km 2 area. More than 500 mineralized veins are
known, every one of which contains visible W0 3 . They are
remarkably persistent but narrow, with an average length
of 200 m (maximum 800 m) and widths varying from 1 cm
to 1 m, generally spaced 3 to 8 m apart. Dips are from 75 °
to vertical and, in addition to wolframite, contain
cassiterite, bismuthinite, molybdenite, and other minor
sulfides (38, p. 93).
The Shizhuyuan deposit in Hunan Province is widely
recognized as the world's largest known tungsten occur-
rence. It is characterized by stockwork greisens super-
imposed upon tactite situated at the contact between a Yen-
shanian granite intrusive and argillaceous limestone and
dolomitic limestone of Devonian age. It was reported to con-
tain 190 million t of ore grading 0.33 pet W0 3 , 0.115 pet
Sn, 0.122 pet Bi, and 0.06 pet Mo (36, p. 436).
23
Table 4.— CPEC in situ resources, January 1983
Location and deposit
Resource.
103 t
Grade,
pet W0 3
Contained
W0 3 . t
Geologic type
Status
Source'
China:
Bai Sha Po
Dalongshan
Damingshan
Dangping
Guimeishan
Huangsha
Hungshuichai
Pangushan
Piaotang
Qmghu
Shangping
Shtzhuyuan
Tajishan
Wengyuan
Xialong
Xiangdong
Xihuashan
Yaokanghsien
Yochang District
Total or average
47.042
1.135
13.962
2.749
2.175
3.294
1.274
1.528
2.432
78.000
695
190.000
3.890
359
851
2.290
17.428
235
488
369.827
0.15
1.00
1.04
88
2.20
1.75
.77
1 90
1.75
38
1.15
.33
.65
1.90
93
72
.65
82
1 90
42
70.563
11.350
145.205
24.191
47,850
57.645
9.810
29.032
42.560
296,400
7,993
627,000
25.285
6.821
7,914
16.488
113.282
1,927
9,272
1.550.588
Tactite vein
D
3
Vein
Stockwork. vein
Vein
do
P
P
P
P
1
3
1
1, 2
do .
do
do
Vein, stockwork
Porphyry
N
N
P
P
D
P
D
P
P
P
P
P
P
P
P
1
1
1, 2
1, 2
3
Vein
Stockwork, tactite
Vein
1. 2
3
2
do . . .
do
do
. . . .do
do
do
Greisen
1, 2
4
4
1, 2, 3
4
1
USSR
2.741
1.179
386
1,181
4.320
400
958
10.910
2.866
1.505
204
475
540
5.000
1.000
50.800
1.400
22.025
1.432
.50
80
60
60
.60
1.00
.60
.43
.43
80
80
60
50
.40
50
60
45
58
60
13.705
9.432
2.316
7.086
25.920
4.000
5.748
46.913
12.324
12,040
1.632
2.850
2,700
20,000
5.000
304,800
6.300
127.745
8,592
1
Antonova Gora
Vein
P
3
Vein, tactite
P
1. 2
Belukha
Vein 1 .
P
1. 2
Boguty
Vein, stockwork
Vein
N
D
1
1, 2
Bukuka
Dzhida Field
Ingichinsk
lul'tin
Vein, stockwork
do
Tactite
P
P
P
1. 2
1. 3
1
Vein
P
3
Kara Oba
Kti-Teberda
Lyangar
Maykhunnsk
Spokomyi
Tyrny-Auz
Verk -Keyraktm
Vostc-2
... .do
do
Tactite
do
Greisen
P
N
P
D
N
1
1
4
1
4
Tactite
P
1. 2
Vein
P
4
Tactite
P
1
Yubilennoye
do
P
1
Total or average
109.322
.57
619.103
Grand total or average
479 149
45
2.169.691
D Developed N Nonproducer P Producer
'Resource data were obtained from the following sources 1— Calculated from published dimensional data on ore body; 2— remaining tonnage calculated
from assumed or known past production; 3— published resource estimate available; 4 — estimate based on capacity and/or assumed life of operation
U.S.S.R.
Although it is the world's second largest producer, with
an estimated 1982 output of 24.6 million lb of WO, (9), the
U.S.S.R. continues to be a net tungsten importer. Principal
tungsten producing regions are the North Caucasus,
Kazakhastan. Uzbekistan, Transbaykal, and the Soviet Far
East '24. p. 458 1. Deposits analyzed for this study contain
nearly 1.4 billion lb of W0 3 .
Tungsten deposits of the U.S.S.R. are of three main
types: contact metamorphic (tactites), greisen, and vein-
stock work. Pegmatites and placers are of relatively minor
importance.
Of the deposits classified as contact metamorphic, those
at Tymv-Auz are undoubtedly the most significant,
ated to contain nearly half of the total tungsten in the
19 Soviet deposits examined. The Tyrny-Auz tungsten-
molybdenum mine, a combined surface and underground
operation, has produced since 1934 and is the main producer
of tungsten in the U.S.S.R. The deposit consists of 20 steeply
dipping orogenically related ore bodies that are worked
along a 1.600-m front to a depth of 900 m (39, p. 104 1.
Scheelite and molybdenite minerals are embedded in
garnet-pyroxenes, calcareous and sulfide skarns, pyroxene-
plagioclase and biotite hornfels, and marbles.
A characteristic feature of greisen deposits is their ob-
vious spatial and genetic association with acidic leucocratic
and often pegmatitic granites. The tungsten-molybdenum
deposit at Akchatau in Central Kazakhstan in the northern
part of the Dzhungar-Balkash geosyncline is an example.
There, Lower Silurian sandstone, siltstone, and argillite
have been folded and intruded by a post-Early Permian in-
trusive complex, the Akchatau granite massif. The deposit
consists of 22 separate greisen bodies, or "clusters," over
an area of 70,000 m 2 (40, p. 194). The deposit is one of the
largest in Kazakhstan, with estimated resources of nearly
14,000 t of contained W0 3 .
Among the hydrothermal tungsten ore deposits of the
U.S.S.R., the following varieties, with examples of each from
deposits evaluated, have been identified: quartz-cassiterite-
wolframite (lul'tin), quartz-scheelite (Boguty), quartz-
wolframite (Antonova Gora, Bom-Gorkhon), and quartz-
sulfide-tungsten (Bukuka, Dzhida Ore Field).
24
MINING AND POSTMINE PROCESSING TECHNOLOGY
The geologic occurrence and nature of tungsten
mineralization usually dictate the mining method. Dif-
ferences in mineralogy and market considerations deter-
mine beneficiation, intermediate, and final tungsten prod-
ucts. Table 5 lists the MEC mines and deposits evaluated
in this study, their status, capacity, mining and beneficia-
tion methods, and primary tungsten product. Figures 16 and
17 contain resource and mine capacity data by status and
mine type for MEC deposits evaluated.
MINING METHODS
Many of the smaller deposits evaluated in this study
are or would likely be mined simply by following
mineralized outcrops from the surface to some depth,
without great regard for grade control, productivity, or
future mine planning. This approach is widely practiced in
Bolivia, Burma, Mexico, Thailand, and several other less
developed countries. For larger deposits in more in-
dustrialized countries, the mining method depends upon
depth and geometry of the ore body, competency of the ore
and country rock, ore grade, development of a mine plan,
and required capital investment.
Surface
Placer mining methods are utilized to recover tungsten
from alluvial and eluvial deposits. The Atolia Placers in
California, a small intermittent producer, was the only
tungsten placer evaluated in this study. It was evaluated at
an annual capacity of 1.3 million t of gravel using front-end
loaders and trucks. The Andrew Mine, a small tungsten pro-
ducer in California, is currently mining talus material using
front-end loaders at an annual ore capacity of 181,000 t.
Nineteen of the deposits evaluated (accounting for 29
pet of total capacity) in this study are or would likely be
mined exclusively by surface methods. The size, efficiency,
and degree of mechanization vary widely. Open pit opera-
tions like those in Mexico, for example, use a minimal
amount of mechanized equipment and depend largely on
pick-and-shovel methods. Labor consists of gambusinos,
small groups of contract miners. Productivity at these labor-
intensive open pit mines is relatively low, approximately
Table 5. — Mine ore capacity, mining and beneficiation methods, product, and status
Location and
deposit
Average
capacity,
103 t/yr
Major method
Mining
Beneficiation
Tungsten
product
Status
Australia:
Kara 180
King Island 420
Mount Carbine 1 ,700
Mount Mulgine 2,000
Torrington 300
Austria: Mittersill 400
Bolivia:
Bolsa Negra 58
Chambillaya 92
Chicote Grande 1 80
Chojlla 280
Enramada 185
Kami 114
Pueblo Viejo 36
Tasna 115
Viloco 3
Brazil:
Barra Verde 194
Boca de Lage 1 03
Brejui 1 90
Zangarelnas 1 05
Burma: Mawchi 125
Canada:
Cantung 350
Logtung 2,000
Mactung 350
Mount Pleasant 650
France:
Montredon 100
Salau 60
Mexico:
Baviacora 30
Los Verdes 300
San Alberto 200
Namibia:
Brandberg West 105
Krantzberg 105
See explanatory notes at end of table.
Open pit Gravity
Room and pillar, cut and fill. . . . Gravity flotation .
Open pit Gravity
... do Gravity, flotation .
... do do
Sublevel stoping Flotation
Lateral stoping
Sublevel caving
...do
Overhand stoping
... do
Combined stoping
Open stoping
Open stope-block caving
Combined stoping
Room and pillar
Room and pillar,
shrinkage stoping.
Room and pillar, open pit.
Room and pillar,
shrinkage stoping.
Shrinkage stoping
Room and pillar
Open pit
Room and pillar
Blasthole open stope
Open
Underhand stoping
Open pit.
...do...
. . . do . . .
. . . do
Sublevel stoping
Gravity
Gravity, flotation .
Gravity
do
do
do
do
.do
do
do
do
do
do
do
Gravity, flotation .
Flotation
Gravity, flotation ,
. . .do
Gravity
Gravity, flotation .
Gravity .
. ..do ..
Flotation
Gravity .
... .do . .
Natural scheelite P
Natural and artificial scheelite . . P
APT P
APT N
APT N
APT P
APT P
Ferrotungsten P
APT P
APT P
APT P
APT P
APT P
APT P
APT P
Natural scheelite P
... do P
... do P
... do N
APT P
Natural scheelite P
APT N
Natural scheelite N
APT N
APT PP
Natural scheelite P
APT P
APT N
APT P
APT PP
APT PP
25
Table 5.— Mine ore capacity, mining and beneficiation methods, product, and status— Continued
Location and
deposit
Average
capacity.
10 3 t/yr
Peru: Pasto Bueno 150
Portugal.
Borralha 106
Panasquiera 520
South Korea: Sangdong 600
Spam:
Barruecopardo 513
La Paniia 250
Santa Comba 200
Sweden Yxsjoberg 150
Thailand
Ooi Mok 60
Doi Ngoem 9
Khao Soon 150
Turkey: Uludag 560
Uganda: Nyamalilo 105
United Kingdom: Hemerdon 1.900
United States:
Adamson 52
Andrew 181
Atolia Placers 1 .300
Emerson 189
Indian Springs 794
Nevada Scheehte 40
Pilot Mountain 350
Pine Creek 338
Springer 318
Strawberry 78
Thompson Creek 25
Tungsten Queen 150
N Nonproducer P Producer
Major method
Mining
Beneficiation
Tungsten
product
Combined underground Gravity
do
Longwall. room and pillar
Combined underground
methods.
Gravity
... do
Combined methods
Open pit Gravity
... do do
Combined underground . . .do
methods.
Cut-fill, sublevel stoping Flotation
Combined underground
methods
Open pit
Open stope
Sublevel stoping. open pit
Open pit
do
Gravity
do
do
do
do
do
Sublevel caving
Surface mining
Placer
Flotation
Gravity
. . . do . .
Shrinkage stopes Flotation
do do
Square set Gravity .
Open pit do
Blasthole stoping Flotation
Shrinkage stoping do
Sublevel stoping Gravity .
Shrinkage stoping do
Cut-fill do
Status
APT
Ferrotungsten . .
APT
Natural scheelite .
APT
APT
APT
Natural scheelite
APT
Ferrotungsten .
... do
APT
Ferrotungsten . .
APT
APT
APT
APT
APT . ..,
APT
APT
APT
APT
APT
APT . :
APT
APT
P
PP
P
PP
N
P
P
PP
P
N
P
PP
PP
P
P
N
PP
P Past producer.
Producing c .
7pc-
Figure 16— Total recoverable resource by status
and mine type.
Figure 17.
type.
-Total ore capacity by status and mine
26
4.5 t per workershift, with a current estimated annual ore
production of only 30,000 t.
Large-scale open pit operations, such as Mount Carbine
in Australia, utilize highly mechanized mining methods
consisting of high-capacity shovels, front-end loaders, and
trucks. Except for tungsten recovered as a byproduct, the
tungsten ore at Mount Carbine is among the lowest grades
currently being mined from MEC deposits. Nevertheless,
owing to the high degree of mechanization, productivity at
Mount Carbine is quite high, approximately 95 t per
workershift, with an annual ore production of approx-
imately 1.7 million t.
Underground
Most (67 pet) of the recoverable tungsten in MEC
deposits evaluated is potentially available from the 38
underground mines and deposits. Room-and-pillar, cut-and-
fill, shrinkage stoping, block caving, sublevel stoping, and
combined mining methods are commonly employed.
Most of the Bolivian tungsten mines are developed on
steeply dipping, irregular hydrothermal veins that require
conventional stoping methods, resulting in high recovery.
These mines range in capacity from 3,400 to 180,000 t of
ore per year. Tasna is atypical among Bolivian tungsten
mines in that nearly 50 pet of its ore production is mined
by small-scale block caving.
The relatively small European tungsten mines, such as
Santa Comba, Mittersill, and Yxsjoberg, generally employ
stoping methods with a productivity ranging from 2 to 11
t per workershift. Wide vein systems are usually mined by
sublevel caving or by sublevel stoping.
The Pine Creek Mine in California is an important pro-
ducer of tungsten in the United States when operating at
full capacity. The mine employs blasthole stoping at a
capacity of 1,300 t of ore per day.
Mineralization in relatively flat-dipping structures can
be mined by room-and-pillar methods. The King Island Mine
in Tasmania, Australia, combines highly mechanized room-
and-pillar methods with cut-and-fill to produce
approximately 420,000 t of ore annually. A productivity of
between 10 and 15 t per workershift is generally
maintained.
The Panasquierea Mine in Portugal is the single largest
producer of tungsten in Western Europe. Production is ap-
proximately 1,625 t/d. Two mining methods are employed,
room-and-pillar and longwall. In the early 1970's room-and-
pillar accounted for 75 pet of production, but in the last 3
or 4 yr longwall methods have been responsible for 80 pet
of production. The change in mining methods has resulted
in decreased dilution and lower capital expenditures for
equipment.
Cantung, British Columbia, also employs the room-and-
pillar method at a capacity of 350,000 t/yr of ore. The pro-
posed Mactung Mine on the Yukon-Northwest Territories
border has plans to use room-and-pillar techniques also,
with an annual capacity of 350,00 t of ore.
The molybdenum deposit at Climax, CO, is mined
employing block caving at a design capacity of about 44,000
t/d. When operating at full capacity, the Climax Mine is
the second largest producer of tungsten (as a byproduct of
molybdenum) in the United States, and seventh largest
among MEC producers.
Solution
Although it was not evaluated in this study, one of the
largest known tungsten resources in the United States is
the Searles Lake evaporite and brine deposit in southern
California. The deposit contains approximately 77,000 t of
W0 3 , much of which could be recovered as a byproduct of
soda ash production. Kerr McGee is currently owner-
operator of several plants that recover soda ash, salt cake,
borax, and potash from Searles Lake brines. The Bureau,
in conjunction with Kerr McGee, has undertaken studies
to test the technical and economic feasibility of recovering
byproduct tungsten from these brines (41 ). Bench-scale pilot
plant studies have shown favorable technical and economic
potential for a commercial tungsten recovery plant at the
Westend facility. Approximately 75 pet of the tungsten con-
tained in brines treated by the Westend pilot plant is poten-
tially recoverable. The process under evaulation employs
ion-exchange as the primary concentration method followed
by chemical precipitation of a tungsten product.
BENEFICIATION OF TUNGSTEN ORES
The brittle nature and high specific gravity of tungsten
minerals (especially scheelite and wolframite) require
careful processing in order to maintain acceptable
recoveries. Nearly all tungsten ores require gravity methods
to produce a concentrate, although some scheelite ores can
be floated efficiently. The iron content of some tungsten ores
allows for their upgrading by magnetic methods.
Most tungsten ores are sized in crushers and grinders.
These processes require careful monitoring because the
brittle nature of tungsten minerals can result in problems
in treatment and recovery. If crushing and grinding are not
closely monitored, the ore minerals will become finer
grained than the gangue minerals and will accumulate with
the finer nontungsten material, making separation more
difficult. In general, the finer grained the ore minerals the
more costly recovery is, owing to the necessity for additional
recovery circuits.
Some mines employ handsorting prior to milling as a
means of upgrading the ore. Doi Ngoem in Thailand and
some of the Bolivian operations utilize this method. Hand-
sorting at Doi Ngoem reduces the volume of total W0 3 by
about 10 pet but, at the same time, upgrades ore from a feed
grade of about 1.60 pet to over 25 pet W0 3 , thus reducing
overall beneficiation costs. At the Xihuashan Mine in
China, approximately 100 people are employed to handsort
3,000 t of ore per day.
The Mount Carbine Mine in Australia employs a highly
advanced photometric separation method, which is essen-
tially an automated "handsorting" method. After crushing
and grinding, but prior to gravity treatment, the ore is mov-
ed by belt and scanned by a light beam that is reflected by
the ore. The reflected light is analyzed by a computer, which
identifies the more reflective ore-bearing quartz from bar-
ren schist. Acceptable ore is blown off the belt by computer
controlled airjets onto another belt that transports the
upgraded ore to secondary and tertiary crushing before it
is sent to the gravity plant, where wolframite and scheelite
concentrates are produced. Figure 18 illustrates the flow
of material at the mill plant.
27
Opencut
mine
Loader
Truck
Primary
crusher
>\ Screen
1 tower
Fines
Wet
screen
tower
Dewatering
Screens
Jigs and spiral
concentrators
Concentrates
To tailings
dam
A-frame
Graded ore
stockpile
Secondary
crushing
Tertiary
crushing
Beneficiation
with jigs and
shaking tables
J?.VV Product
0\o'5>oC\ stockpile
)° :, Waste
°.b b'°" stock P |le
ABWft'f&KSl
Haulage
Waste dump
I I
Concentrate
recirculated
Tailings
Rod grinding mill
Jigs and spiral
concentrators
Crude
concentrates
Concentrate cleaning section
Rotation tables
Dry magnetic separation
Shaking tables
High tension separation
Wolframite
I
Scheelite
To tailings dam -*■
I
nl Drummed concentrates
U U dispatched overseas
Figure 18.— Flowsheet. Mount Carbine operation.
After crushing and grinding 'and handsorting at some
mines i, nearly all tungsten ores are separated by gravity
techniques using jigs, cyclones, and or tables. Concentrate
grades of 70 pet are often produced using gravity methods.
For commercial reason.-, standard grade scheelite concen-
trates are expected to assay more than 70 pet WO,.
wolframite 60 pet. Producers employing gravity separation
techniques include all evaluated Bolivian, Australian, and
Brazilian opi u
Additional treatment of gravity concentrates is
times practiced as an upgrading process. Magnetic
separation isol edton move ilmenite, magnetite, and
28
other minerals. At Uludag, Turkey, approximately 70 pet
(by weight) of the feed is rejected by dry magnetic separa-
tion. If sulfides are present in the gravity concentrates, flota-
tion or roasting is often used to upgrade the concentrate.
This is of particular importance in the case of wolframite
mineralization, which is often associated with sulfide and
arsenide minerals.
Some scheelite ores can be effectively concentrated
using flotation. Flotation recoveries can reach about 80 pet
and generally produce a tungsten concentrate of between
65 and 70 pet W0 3 .
Sangdong (Republic of Korea) and Mittersill (Austria)
are probably the most vertically integrated tungsten opera-
tions in the world. The operations produce artificial
scheelite, APT, high-grade natural scheelite, tungsten
metal, tungsten oxide, and carbide powder. Sangdong also
produces byproduct bismuth and molybdenum. Sangdong's
postmill processing plants have high capacities and the flex-
ibility to respond to changing market demands by varying
their product output. Figure 19 is a simplified flowchart of
Sangdong's concentration method. Mined ore is ground,
classified, and floated. Flotation separates the sulfide
minerals, resulting in the production of a bismuth-
molybdenum concentrate from the scheelite minerals that
are contained in the tails. The tails pass to flotation cells,
from which a low-grade tungsten concentrate (10 pet W0 3 )
is recovered. The 10-pct concentrate is upgraded by grav-
ity concentration to a 65-pct W0 3 concentrate and an 8-pct
W0 3 tailing. The 65-pct concentrate is leached with acid
to remove apatite and other impurities. The final concen-
Feed
Tails
Bi-Mo
concentrate
Promoter
Fuel oil
Oleic acid
Sodium silicate
Soda ash
Scheelite
rougher
flotation
Concentrate
Final
tailings
Concentrate
Acid
leach
Wet table
gravity
concentration
Natural
scheelite
Tails
Chemical
plant
APT
Figure 19. — Flowsheet, Sangdong concentration process.
trate assays 72 pet W0 3 . The 8-pct W0 3 tailings are
reground and tabled. This upgraded material is then con-
verted to artificial scheelite. Some of the artificial scheelite
is converted to APT, the amount depending upon market
needs.
As mentioned previously, some operations produce
tungsten concentrates that require additional treatment
before they can be processed to APT or ferrotungsten. This
is practiced to reduce consumption of chemicals and energy
requirements. Major upgrading processes are flotation to
remove base metal, arsenic, and molybdenum sulfides;
magnetic separation to remove wolframite and garnet; elec-
trostatic separation to remove cassiterite; roasting to
eliminate arsenic, sulfur, flotation oils, and organics;
grinding to ensure higher solubility; and acid leaching to
remove carbonates.
POSTMILL PROCESSING
Tungsten concentrates can be converted to a variety of
tungsten products. Products are determined primarily by
the chemical composition of the concentrate, but marketing,
geographical, and political factors also play a role. In this
study, APT, artificial scheelite, natural scheelite concen-
trate, and ferrotungsten were considered as marketable
tungsten products. Operations that produce wolframite con-
centrates (e.g., several Bolivian mines) were assumed to
have their concentrates transported to Europe to be con-
verted to APT.
Ammonium Paratungstate (APT)
Concentrate is the primary tungsten unit in the
tungsten industry and APT is the largest consumer of con-
centrate. APT is an intermediate product, in powder form,
for virtually all major tungsten products (fig. 1). Although
there are several methods to produce APT, the most wide-
ly employed method is comprised of the following four main
stages (fig. 20):
1. Autoclave digestion of the concentrate with soda ash
to dissolve the tungsten minerals.
2. Removal of impurities from the sodium tungstate
solution (primarily molybdenum and silica).
3. Organic solvent extraction to concentrate and purify
the sodium tungstate solution and convert it to an am-
monium salt solution (APT).
4. Crystallization and drying of the APT from the am-
monium solution.
Feed to most APT plants is in the form of scheelite and
wolframite containing approximately 65 pet W0 3 , plus im-
purities including arsenic, molybdenum, and sulfur. In some
cases, the concentrates are roasted to decrease the sulfur
and arsenic content or preleached with acid to remove
carbonates.
The purpose of the first stage is to convert tungsten con-
centrate into sodium tungstate by pressure leaching with
soda ash. The resulting slurry is cooled and filtered. The
insoluble portions are recovered and discharged to waste.
Approximately 98 pet of the tungsten and molybdenum are
dissolved in the pressure leaching step.
The second stage consists of the removal of the principal
impurities from the sodium tungstate solution, primarily
molybdenum and silica.
In the third stage, a circuit removes any remaining im-
purities not removed in the previous stage and also contains
29
Scheelite concentrate
(or blend of W0 3 concentrates)
(65 pet W0 3 )
Scheelite concentrate teed
(7-15 pet W0 3 )
Digester
■
i
Removal of
impurties
'
i
Molybdenum
recovery
Organic
phase
I
i
i
Molybdenum
Crystallizer
Dissolution of
tungsten minerals
Purification by
solid waste
removal, precipitation
of contaminant
Organic extraction
process and
conversion to APT
Precipitation of APT
solution crystals
{
Autoclave
Residual
' r
tungsten
Impurities
removal
■
Recovery of
residual
tungsten
and
molybdenum
solids
1
Precipitation
\
■
Molybdenum
Dryer
Pelleti?er
Packaging
Autoclave
digestion to
produce sodium
tungstate solution
Removal of
impurities
(principally silica
and molybdenum)
Precipitation of
tungstate
Drying and
packaging of
artificial scheelite
APT
Figure 20. — Flowsheet, ammonium paratungstate production
process.
Artificial scheelite
(CaWO«)
Figure 21 .—Flowsheet, artificial scheelite production process.
circuits to convert the sodium tungstate solution to am-
monium tungstate.
The fourth stage is the preparation of the final dried
product from solution. This is accomplished by producing
an oversaturated solution causing precipitation of APT
crystals. The crystals are dried, ground, and packaged.
Assays are usually between 89 and 90 pet W0 3 , and con-
tain minor impurities 'table 6).
Table 6.— Chemical composition of APT
Assay
Elements, ppm:
AJ
Ca
Fe
Mo
Na
Compounds, pel
NHj
W0 3
Ignrtion loss
Moisture
5
10
20
25
20
15
5.4
'89
pel
11
pet
0.5
•70 5 pet W
Artificial Scheelite
Artificial or synthetic scheelite (CaWOj is produced
from low-grade concentrate- 7 I 20 pet \VO,i. usually at
the minesite. The processing yields a high-grade tungsten
concentrate free of impurities (especially molybdenum). The
production of artificial scheelite is an alternative method
to selective flotation, which produces a high-grade scheelite
concentrate. The most significant producers of artificial
scheelite in the MEC's are Sangdong in the Republic of
Korea, and King Island in Australia.
Synthetic or artificial scheelite is used primarily as a
direct additive to molten steel for tungsten alloys. The proc-
ess for production of artificial scheelite (fig. 21) consists of
the following four major stages:
1. Autoclave digestion with soda ash to produce sodium
tungstate.
2. Removal of impurities.
3. Precipitation of the tungsten or calcium tungstate
and packaging.
4. Recovery of residual tungsten from impurities.
Stage 1 consists of the digestion of scheelite concentrate
with soda ash. The process produces soluble sodium
tungstate and leaves impurities as solids. The solutions and
solids are separated by filtration, and the solids arc
to a disposal site.
Stage 2 is designed to precipitate any impurities that
remain in the sodium tungstate solution, primarily silica
and molybdenum. The molybdenum compounds are ti 1
to recover residual tungsten in stage 4.
In stage 3, the sodium tungstate is healed and ch
ically treated in order to cause precipitation ol
tungstate. The resulting precipitate is w
pelletized. The pellets are 1
In stage 4, any residual tungsti
returned to stage 1. Overall, tungsten r<
imately 98 pet. Typical as
scheelite are listed in table 7.
30
Table 7.— Chemical composition of natural and artificial
scheelite, percent
Natural Artificial
As ."' 0.01 0.01
B\ .'.'.'.'.'. • 01 01
CaO 22.14 22.25
Cu Trace Trace
Fe ' 1 00 30
Mn 03 Trace
Mo ". '.'. 1 00 02
p .01 03
Pb Trace Trace
S ...... 03 .30
g D Trace Trace
Si0 2 .'.'.'.'.'.'.'.'.'.'.'.'.'. 2.68 .40
Sn Trace Trace
W0 3 730 ° • 75 00
Zn 02 .01
Scheelite Concentrate
Some mining operations, such as Cantung in Canada,
King Island in Australia, and Sangdong in the Republic of
Korea, primarily produce natural scheelite concentrate,
which requires little, if any, special beneficiation steps.
Natural scheelite contains variable amounts of
molybdenum because of the close geochemical relationship
between scheelite and powellite mineralization. Natural
scheelite concentrates are suitable as direct feed to the tool
steel industry where molybdenum is desirable.
Natural scheelite concentrates are produced in quantity
at Sangdong. In 1983, the mine was the largest and most
important MEC producer of natural scheelite. These con-
centrates, typical of most scheelite concentrates, contain up
to 1.7 pet Mo, 3.80 pet Si0 2 , less than 0.01 pet As, plus other
minor constituents (table 8). In comparison, artificial
scheelite contains up to 0.02 pet Mo, less than 0.70 pet Si0 2 ,
and less than 0.01 pet As.
Wolframite or ferberite
concentrate feed
Crushing
'Ferrotungsten
slag
(50-55 pctW)
Waste
slag
Roasting
Preparation
for arc
furnace
Primary arc
furnace
Cooling
crushing
Secondary
arc furnace
Reduction (when
As and S 2 present)
Drying, briquetting,
crushing
80 pet
ferrotungsten
packing
Preparation of slag
(15-25 pet W) for
secondary arc furnace
Smelting of slag
High-grade
ferrotungsten
Figure 22.— Flowsheet, ferrotungsten production process.
Table 8.— Chemical composition of ferrotungsten, percent
Assay
As '0.10
C .60
Cu .10
Mn .75
P .06
S .06
Sb '.08
Si 1.00
Sn '.10
W0 3 288-99
'Sum of As, Sb, and Sn not to exceed 0.2 pet.
2 70 to 80 pet W.
Ferrotungsten
Ferrotungsten is produced from tungsten concentrates
by various methods. The most commonly used is the elec-
tric carbon arc reduction process (fig. 22). Ferrotungsten is
produced from clean ferberite concentrates or from a
scheelite and wolframite admixture. The concentrates
should be low in manganese. Table 8 shows the composi-
tion of a typical ferrotungsten concentrate. If sulfides or
arsenides are present in the concentrate, prior roasting may
be required.
The electric arc reduction process consists of two
stages— reduction of concentrates and secondary arc reduc-
tion. In the first stage, the concentrate is briquetted with
carbon, lime, and fluorspar, and smelted along with recycled
low-grade slag from the secondary arc furnace. Lime and
fluorspar are added to flux the silica and other impurities.
The first or primary stage smelting results in a product
assaying 15 to 25 pet W, which is further processed in the
second stage furnace, resulting in a high-grade fer-
rotungsten product assaying 80 pet W, which is sized and
packaged. The slag from the secondary furnace is crushed,
ground, and dried, followed by briquetting with charcoal
and recovered dust. Silica, lime, fluorspar, and bauxite are
once again added as fluxes. The mixture is heated to 2,000°
C and the resulting metal, assaying 50 to 55 pet W, is fed
to the primary stage furnace. The overall recovery of
tungsten from concentrates ranges from 97.5 to 99 pet. The
losses usually occur from dust, fumes, and handling.
31
OPERATING AND CAPITAL COSTS
Operating and capital investments for the apropriate
mining, beneficial ion. and postmil] processing methods
were estimated for each property. Where possible, actual
mining capital and operating costs were gathered from
published material or contacts with company personnel
When actual costs were unavailable, costs were either
estimated using standardized costing techniques or derived
from the Bureaus capital and operating cost manual using
the cost estimating system CES i2).
OPERATING COSTS
Operating costs for the mine and mill include materials
utilities, labor, administrative costs, facilities maintenance
and supplies, and research. The operating costs presented
in this section are weighted averages based on a per-metric-
ton-of-ore basis and per pound of W0 3 in the tungsten pro-
duct i APT. ferrotungsten. artificial scheelite, and scheelite
concentrate' over the life of the operation.
Operating costs were analyzed on the basis of mine type
'surface, underground i. and on an individual and/or
aggregated country basis.
Surface and Underground
At the time of this analysis, 8 surface and 30
underground mines were considered to be producers and
11 surface and 8 underground properties were non-
producers. Figure 23 shows weighted average operating
costs for producers and nonproducers. presented in terms
of dollars per metric ton of ore and dollars per pound of
recovered \\ 3 in product. Within each category, the costs
are further broken down into three components: mine mill
and postmill processing 'which includes transportation to'
the location of processing to the first marketable product)
Properties with the lowest operating costs generally
utilize efficient mining techniques and modern equipment
resulting in high productivity levels. The property with the
lowest mine operating cost per metric ton of ore is the
Andrew Mme in California, which is a surface operation
using a front-end loader on easily accessible broken colluvial
material. Among producing surface operations, the highest
mine operating cost is at Baviacora, Mexico, where
primitive hand mining techniques are employed, resulting
in very low productivity.
Among underground operations, higher operating costs
are generally associated with more complex ore bodies
unstable ground conditions, and complex ores that require
expensive beneficiation techniques. In the case of Bolivia
Mexico, and other less developed countries, low productivity
is an important factor t umbuting to relatively hieh
operating costs.
Figure 23 indicates that, as expected, for surface opera-
tions, nonproducers are more costly than producers
However, for underground operations, nonproducers are less
costly, in terms of both dollars per metric ton of ore and
dollars per pound of W0 3 . The reason for this anomaly is
that properties evaluated as underground nonproducers in-
clude large, highly mechanized, relatively low cost opera-
tions (e.g., Mactung, Mount Pleasant). This cost differen-
tial is indicated in the mine cost portion of total operating
costs. For underground nonproducers, the weighted average
mine cost is $13.90/t ore, compared with $20 20/t for
underground producers. Also contributing to this cost dif-
ference is that the figure for underground producers in-
cludes several relatively high cost operations in the United
btates, many of which have shut down or severely curtailed
production since the time of this analysis. The six producing
U.b. properties are among the highest cost operations
evaluated. The weighted average mine operating cost for
these properties is $30.60/t ore (versus $20.20/t for all
underground producers).
This cost anomaly (i.e., nonproducers more costly than
producers) is even more apparent in terms of dollars per
pound of W0 3 . The total operating cost for underground non-
producers is 43 pet lower than for producers ($2.45 versus
$4.30), compared with 12 pet lower cost ($38.35 versus
*«iL05) in terms of dollars per metric ton of ore. This is due
to the grade differences among underground properties The
weighted average feed grade for nonproducers is 0.74 pet
W0 3 , compared with 0.53 pet for producers.
It must be noted that the anomalous cost difference be-
tween nonproducing and producing underground properties
does not hold true when an economic analysis is performed
Nonproducers would require large capital investments that
Surface
$9 15
$12 10
$4 90
f 1
Producers
Nonproducers
Producers
Nonproducers
245
$5 70 r
Figure 23-Operat,ng costs, surface versus underground. Dollars
$4 30
$38.35
r^*3,o 5
KEY
Mine operating cost
J J Mill operating cost
LNX\N| Postmi'l processing cost
per metric ton of ore (top) and per pound of WO, (bottom).
32
must be recovered when the properties begin production,
while much of the investment for producing mines has
already been depreciated. The weighted average total pro-
duction cost for nonproducing underground properties is
$5.35 at 0-pct DCFROR, compared with $4.30 for producers.
At a 15-pct DCFROR, the costs are $7.20 and $5.30,
respectively.
When comparing costs on a per-metric-ton-ore basis for
surface versus underground properties, underground prop-
erties are substantially more costly than their producing
onproducing counterpart" On a doll8r-per-pcurjd-W0 3
is, though, both producing and nonproducing
underground properties are less costly than their surface
counterparts ($4.30 for underground producers versus $4.90
for surface producers, $2.45 for underground nonproducers
versus $5.70 for surface nonproducers). Feed grades again
account for this anomaly. The weighted average feed grade
for underground producers averages 0.53 pet W0 3 , com-
pared with 0.14 pet for surface producers. Likewise, the
weighted average feed grade for underground nonproducers
averages 0.74 pet, compared with 0.13 pet for surface non-
producers. Clearly, the feed grades of properties that do or
would produce as underground mines are sufficiently high
to offset the higher operating costs associated with
underground mining methods.
Regional Overview
Figure 24 illustrates operating costs for producing and
nonproducing tungsten properties aggregated by region or
country groupings. The costs are presented in three
Table 9.— Commodity prices used in study
Price
Ammonium paratungstate (APT) lb $5.37
Arsenic trioxide (As 2 3 ) lb .45
Bismuth lb . . 1 .33
Copper lb . . .79
Ferrotungsten lb . . 5.61
Gold tr oz 480.00
Lead lb. . .22
Molybdenum lb . . 3.83
Scheelite 1 lb 3.63
Silver tr oz 1 2.40
Tin lb. . 5.53
Zinc lb. . .39
'Artificial and natural.
segments: mine, mill, and postmill processing. Also shown
are credits derived from the sale of byproducts. Prices used
to determine byproduct revenues are shown in table 9.
Producers
The seven producing United States properties (one sur-
face, six underground) have the highest weighted average
total and mine operating costs of the country groupings
shown. The mine operating cost for U.S. producers averages
$3.58/lb W0 3 ($27.19/t ore), compared with $2.35/lb
($12.16/t) for all producers, and the total operating cost for
underground U.S. producers is $6.33/lb ($48.33/t), versus
$4.69/lb ($24.65/t) for all underground producers. The high
cost of U.S. producers relative to producers as a whole
results from expensive mining methods that must be
employed at some U.S. operations.
The low mine operating cost ($0.99) for the "other"
Producers
KEY
Byproduct credit
I Mine operating cost
E".". , . , . , .i
:■:•:•:•:•! Mill operating cost
[^\^\| Postmill processing cost
DOLLARS PER POUND OF W0 3
Figure 24. — Operating costs, regional basis.
33
country grouping is heavily influenced by two properties
(Sangdong. Republic of Korea, and Canning. Canada) which
together account for nearly 23 pet of the average annual
WO s produced at the 3S producing properties. These two
properties are highly mechanized, efficient operations with
high grades. The in situ grade is 1.32 pet WO. at Canning.
0.86 pet at Sangdong. The Si. 54 mine cost for Australia is
heavily weighted towards King Island, which accounts for
nearly 50 pet of the annual recoverable W0 3 for the three
Australian producers evaluated. Although an underground
operation. King Island has a high grade compared with the
two producing lian properties (Kara and
Mount Carbin< King Island's in situ grade averages 1.03
pet WO . compared with 0.73 pet at Kara and 0.10 pet at
Mount Carbine.
Mil] operat sts are comparable for all country
groupings except Bolivia ($0.80) and "other" ($0.72). Boli-
vian milling operations enjoy the advantage of low labor
and high feed grades. The in situ grade for Bolivian
- ts averages 0.71 pet W0 3 . considerably higher than
for all but Thailand and the Republic of Korea (Sangdong
only. As is the case with mining costs, the relatively low
mill operating cost for the "other" group is affected by Can-
tung and Sangdo;
Postmill processing cost includes the cost of processing
low-grade tungsten concentrate to the first marketable prod-
uct 'artificial scheelite or APT), the cost of processing
byproducts to a marketable form, and transportation to the
point of sale. This cost can thus vary widely among the prop-
erties evaluated. The weighted average cost in this category-
is approximately $1.00 for all producers. Among the coun-
-roupings shown in figure 24. Bolivia has the highest
postmill cost 'SI. 46) since most production from that coun-
try was assumed to be converted to APT in Europe;
transportation is a significant portion of the cost. The low
postmill processing cost for Peru and Brazil is largely af-
fected by the low cost of Brazilian properties, which pro-
duce natural scheelite. In fact, nearly all of the postmill
operating cost for this group is attributable to Pasto Bueno.
Peru, which produces copper, lead, zinc, and silver as
byproducts. These byproducts, however, account for the
$0.29 credit for this group of properties.
Nonproducers
Among nonproducers, the five U.S. properties have the
highest cost in all categories, resulting in a substantially
higher total operating cost than for all other country group-
ings. Mine operating cost for U.S. nonproducers averages
$2.79, compared with an average of $1.63 for all non-
producers; the average total operating cost for U.S. non-
producers is $7.6' $3.91 for all nonproducers. This
is in part a consequence of the fact that the selection pro-
cess of properties for this study resulted in inclusion of a
relatively large number of deposits in the United States,
for which resource data are more readily available than for
nonproducing deposits in foreign countries. Adequate
resource data are generally available only for foreign
dep*. are likely to be developed in the forseeable
future owing to their favorable cost position relative to
producers.
In this instance, the high cost of U.S. nonprodua
compared with all nonproducers is not attributable to grade.
In fact, the a ■ pet WO, for U.S. nonproducers
|ual to the average for all nonproducers evaluated On-
reason for the comparatively high cost of 1 S. nonproducers
is the difference in capacity bet 3 nonproducci
other nonproducers. The average capacity for U.S. non-
producers is 670 t yr WO .„ versus 863 for all nonproducers.
More importantly, U.S. properties would be mined using
relatively expensive methods dictated by the characteristics
oi' the ore bodies, which are similar to those at producing
U.S. operations that experience high operating costs. As
discussed earlier, relatively high labor rates in the United
States represent a substantial portion of the operating cost
of U.S. operations.
The relatively large byproduct credit for African non-
producers is attributable to the potential recovery of signifi-
canl amounts of tin from the Brandberg West property. The
postmill processing cost for the three properties in this group
is correspondingly high in comparison with other groups,
but the net operating cost (mine plus mill plus postmill proc-
essing minus byproduct credits) compares favorably with
that for other country groupings. The net operating cost for
Africa is $3.99. lb W0 3 , compared with an average of $3.54
for all nonproducers.
Producers Versus Nonproducers
The weighted average total operating cost for non-
producers is lower than that for producers ($3.91 versus
$4.69, not including byproduct credits). This primarily
results from the low mine cost for nonproducers, which, as
stated earlier, is largely influenced by a few large, low-cost
properties with relatively high grades. The most important
of these is Mactung, Canada, with an average in situ grade
of 0.96 pet W0 3 , and a high-grade portion containing 15
million t grading 1.37 pet. As stated earlier, however, this
apparent discrepancy disappears when an economic analysis
is performed, since nonproducers would require large capital
investments that must be recovered when production
begins.
POSTMILL TRANSPORTATION AND PROCESSING
The transformation of tungsten concentrates available
to the MEC's into the intermediate products of APT and
ferrotungsten is practiced primarily in the industrialized
countries of Japan, Republic of Korea, Austria, the United
States, and Western Europe.
There are several countries that produce significant
amounts of APT from concentrates for the western market.
They include Austria, Japan, China, Republic of Korea, the
United Kingdom, and the United States. Much of the con-
centrate treated originates in other countries.
To the United States, the most important exporters of
APT are France, China, Republic of Korea, Sweden, and
the Federal Republic of Germany. The major U.S. producers
are Union Carbide in Pine Creek, CA; AMAX at Ft.
Madison, IA; Sylvania at Towanda, PA; and General Elec-
tric in Cleveland, OH.
None of the producing mines evaluated in this study pro-
duce artificial scheelite as a primary product. In every case,
artificial scheelite is produced at or near the minesite. The
two largest art ificial scheelite producers are at King Island,
Australia, and Sangdong in the Republic of Korea.
Ferrotungsten is produced in tnosl industrialized coun-
tries principally from scheelite and ferberite concentrates.
Ferrotungsten 's application in alloy makes it an integral
part of any well developed tool steel industry. Most fer-
rotungsten producers also manufacture other ferroalloys
such as ferrovanadium, fei romolybdenum, ferrochromium,
and ferrotitanium.
34
In general, annual plant capacities range between 100
and 2,500 t of ferrotungsten. Austria, Belgium, Brazil,
France, Japan, Portugal, the United Kingdom, and the
Federal Republic of Germany are major ferrotungsten pro-
ducers. Smaller ferrotungsten producers are India, Luxem-
bourg, Mexico, Republic of Korea, and Spain.
Union Carbide has the only large ferrotungsten plant
in the United States. The plant has an annual capacity of
about 7 million lb of ferrotungsten. Molycorp has a plant
in Washington, PA, but its output is very small. The United
States is currently a net importer of ferrotungsten.
Transportation
Table 10 lists the actual or assumed destination and
product form for producing and nonproducing properties
evaluated. In most cases, the destination for postmill
processing and the tungsten product were known. For other
producing and nonproducing mines, assumptions were
necessary. In some cases, concentrates might be sent to dif-
ferent countries owing to year-to-year changes in sales
contracts.
For some deposits, final tungsten products were not
known. When concentrates were low-grade scheelite con-
taining arsenic, sulfides, or other contaminants, or when
the concentrates were wolframite, APT was the assumed
product. Ferrotungsten was assumed in the case of ferberite.
Clean scheelite concentrate was assumed to be sold free on
board (f.o.b.) at the mill.
Table 10 indicates that all domestic concentrates are
converted within the United States, but the United States
also treats concentrates from Canada and Mexico. Most of
Bolivia's tungsten concentrates are shipped to Europe
although some portion is probably shipped to Japan and the
United States. Most Bolivian concentrates are shipped from
Antofagasta, Chile, to Europe for processing.
Transportation costs for concentrates requiring further
treatment, whether to APT or ferrotungsten, are generally
very similar. Grade apparently does not play a major role
in determining shipping rates. International transportation
costs for shipping tungsten concentrates to major destina-
tions were estimated using available concentrate shipping
schedules for ocean transport. The costs include all charges
from receipt on the shipping pier from a land carrier to
loading on a land carrier at the destination ocean port. The
estimated shipping costs listed in table 11 do not include
custom duties or custom broker charges. Land transporta-
tion, specifically rail and/or truck, were estimated on a
deposit-by-deposit basis.
Processing Costs
The operating costs for processing tungsten concentrates
depend on a large number of factors, including desired
product, concentrate grade, mineralogy and contaminants,
reagent costs, power and labor costs, and the age of the plant
and its capacity. The following discussion presents the costs
for production of APT, ferrotungsten, and artificial scheelite
(in January 1981 dollars). A U.S. location and U.S. labor
rates were assumed. All direct and indirect costs for labor,
electricity, fuels, chemicals, and parts are included. Land
acquisition, finance costs, legal expenses, depreciation, and
custom toll charges were not included.
Ammonium Paratungstate (APT)
The operating cost estimates in table 12 represent a
Table 10.— Actual or assumed destinations for tungsten
concentrate
Location and deposit
Status
Primary tungsten
product
Point of sale
Australia:
Kara
King Island
Mount Carbine . .
Mount Mulgine . .
Torrington
Austria: Mittersill
Bolivia:
Bolsa Negra
Chambillaya
Chicote Grande .
Chojlla
Enramada
Kami
Pueblo Viejo . .
Tasna
Viloco
Brazil:
Barra Verde ....
Boca de Lage . .
Berujui
Zangarelhas ....
Burma: Mawchi
Canada:
Cantung
Logtung
MacTung
Mount Pleasant .
France:
Montredon
Salau
Mexico:
Baviacora
Los Verdes ....
San Alberto
Namibia:
Brandberg West
Krantzberg
Peru: Pasto Bueno . .
Portugal:
Borralha
Panasquiera. . .
Republic of Korea:
Sangdong.
Spain:
Barruecopardo . .
La Parilla
Santa Comba. . .
Sweden: Yxsjoberg .
Thailand:
Doi Mok
Doi Ngoem
Khao Soon
Turkey: Uludag
Uganda: Nyamalilo . .
United Kingdom:
Hemerdon.
United States:
Adamson
Andrew
Atolia Placers . .
Emerson
Gunmetal
Indian Springs .
Nevada
Scheelite
Pine Creek
Springer
Strawberry
Thompson Creek
Tungsten Queen
Producer
. . do
...do
Nonproducer .
...do
Producer
.do
.do
.do
.do
.do
.do
.do
.do
do
Scheelite f.o.b.
. . .do f.o.b.
APT Japan.
APT Japan, Europe.
APT Do.
APT f.o.b.
APT Europe.
Ferrotungsten
APT
APT
APT
APT
APT
APT
APT
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
.do
.do
do
Nonproducer .
Producer
. . . do
Nonproducer .
...do
...do
... do
Producer .
...do
Nonproducer .
Producer
Nonproducer.
. . . do
Producer
..do
do
.do
Scheelite f.o.b.
. . .do f.o.b.
. . do f.o.b.
. . .do f.o.b.
APT Japan, Europe.
Scheelite United States,
Canada.
APT Do.
Scheelite Do.
APT Europe.
APT Do.
Scheelite f.o.b.
APT United States.
APT Do.
APT Do.
APT Europe.
APT Do.
APT • Europe, Japan.
Ferrotungsten
APT
Scheelite ....
Europe.
Do.
Do.
do
do
do
do
Nonproducer .
Producer
Nonproducer.
Producer
Nonproducer
.do
Producer
. . . do
Nonproducer.
Producer
Nonproducer
... do
APT Do.
APT Do.
APT Do.
Scheelite f.o.b.
APT Japan, Europe.
Ferrotungsten . . Do.
... do Do.
APT Europe.
Ferrotungsten . . Do.
APT Do.
APT United States.
Producer
. . . do
..do
. . do
Nonproducer .
... do
APT
APT
APT
APT
APT
APT
APT
APT
APT
APT
APT
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
35
Table 11.— Port handling and transportation costs for
selected major tungsten concentrate trade routes. January
1981 dollars per metric ton of concentrate
From —
To-
Cost
Melbourne. Australia
Canada
Ba->ot
All properties that produce other commodities in addi-
tion in tui gsl edited with revenues from the sale
of tho.-e byproducts. Additional expenditures required for
the recovery of those byproducts are charged against the
operation.
The relatively low price;- that have prevailed in the
tungsten market since late 1981 have caused many proper
including most of the U.S. properties) to spend some
portion ol 1982 and 1983 temporaril) closed. For purposes
of this investigation, properties that are temporarily shut
down hut that ma\ reopen in thi short run are still classified
a.- producers and assumed to be producing at full capacitj
after 1983.
Two separate analyse- were done for this study with
alternate rate ol I rn on in ified.
Avei i il cost et production over the hie of each
property was estimated first with a required DCFROR of
15 pet. then with a required DCFROR of pet. The 0-pct
rate is used to evaluate the breakeven point where revenues
are sufficient to recover total investment and production
costs over the operation's life but provide no positive rate
of return. This rate could reflect the investment parameters
of a project given only market share or developmental con-
cerns, where potential multiplier effects (e.g., social benefits)
would offset the lack of company and/or operation-specific
profitability. For privately owned enterprises or those not
strictly developmental in natui;e a more reasonable
economic decisionmaking parameter is represented by the
15-pct DCFROR. This rate was considered the minimum
return sufficient to maintain adequate long-term
profitability and attract new capital to the industry.
Summary results from the cost evaluations are shown
in figure 27. Total production costs for properties included
in the country groupings are broken down into three
segments: total operating cost, cost at 0-pct DCFROR, and
cost at 15-pct DCFROR. The product and country groupings
Scheelite producers
KEY
Total operating cost
0-pct DCFROR
RS^I 15-pct DCFROR
xWWWWWWW^
— „
x\\\\\\\\\^
Ex\x\WWWWM
nzs^^^^^^v^^^
I ~~~
J
'0 15 20
DOLLARS PER POUND OF W0 3
Figure 27— Total production costs.
25
'A,
40
correspond with the results as shown in the following sec-
tions of this report. Availability of each product type is
discussed in the following sections of this report, along with
a more extensive discussion of costs as related to
availability. A few general comments relating to figure 27
are worth noting here.
The costs for scheelite producers are low compared with
corresponding costs for other product types. This is partly
due to the fact that scheelite from the nine producing
properties can be sold directly as a concentrate, so that
postmill processing (as defined in this report) includes on-
ly transportation. Also, the weighted-average costs for
scheelite producers are dominated by the two large, efficient
operations at Sangdong and Cantung. These two properties
account for 50 pet of the more than 120,000 t of recoverable
W0 3 in producing scheelite properties evaluated.
Among the country groupings shown for APT producers,
the weighted-average costs (all three cost categories) for U.S.
properties are highest. Reasons for this were discussed in
the "Operating Cost" section of this report. Note also the
high 0- and 15-pct costs for APT nonproducers relative to
corresponding costs for APT producers. The high costs (at
and 15 pet) for nonproducers reflect the recovery of large
capital expenditures necessary to develop these properties.
The costs for ferrotungsten producers cannot be direct-
ly compared graphically with other costs shown, as fer-
rotungsten costs are in terms of dollars per pound of W,
while all others are in terms of dollars per pound of W0 3 .
By converting ferrotungsten costs to W0 3 equivalents, each
of the cost segments would be shorter (i.e., costs would be
lower) by a factor of 0.79. Thus, in terms of W0 3 , the average
total operating cost for ferrotungsten producers is $5.08 (in-
stead of $6.43). At pet the cost is $5.77 (instead of $7.31),
and at 15 pet, the cost is $6.56 (instead of $8.30).
More detailed results from the cost evaluations of all
product forms are presented as availability curves in the
following sections. Total availability curves were con-
structed by aggregating the results from the individual
deposit evaluations. The curves constructed for each of the
three tungsten product forms show total tonnage available
from each property at the estimated average total produc-
tion cost value solved for using the DCFROR techniques
described. Deposit tonnages are ordered on these curves
from those having the lowest associated average total cost
to those having the highest. Potential tungsten availabili-
ty can be seen by comparing an expected long-run constant-
dollar market price to the estimated average total cost
values shown on the availability curves.
Annual availability curves are also constructed and
presented in the report. These curves show amounts of
tungsten potentially available each year at various levels
of average total cost of production. These curves reflect the
current installed capacity levels at producing deposits, in-
cluding known expansion and development plans, and
assumed capacity levels and development schedules at
undeveloped deposits.
TUNGSTEN AVAILABILITY
At the demonstrated resource level, approximately 1.2
million t of W0 3 is potentially recoverable from 57 primary
tungsten mines and deposits in MEC's (nearly 146,000 t,
or 12 pet from the United States). An additional 100,000
t of W0 3 is potentially recoverable as a byproduct from the
Climax molybdenum mine in Colorado and 77,000 t from
the Searles Lake evaporite and brine deposit in California.
These deposits were not evaluated because byproduct
tungsten revenues were a small proportion of total
revenues. Tungsten is recovered at the Climax operation
but not at Searles Lake. A recovery method for tungsten
from the Searles Lake brine has recently been developed
by the Bureau (41), but commercial application has not as
yet taken place. Tungsten is also available in small quan-
tities as a byproduct from other mines around the world,
most notably tin. Some tungsten is recovered from
molybdenum, copper, gold, and lead-zinc mines, but data
on actual amounts recovered are generally unavailable.
Properties with byproduct tungsten were not included in
the evaluation sections of this study, but are included in
the discussion of future availability at the end of this
section.
Nearly 2.2 million t of W0 3 is contained in 38 mines
and deposits in the U.S.S.R. and China that were examin-
ed in the study (and discussed in the "Geology and
Resources" section). At 70 pet recovery (the average
recovery rate at MEC operations evaluated was nearly 69
pet), this translates to 1.5 million t of potentially recoverable
W0 3 . Total potentially recoverable W0 3 examined is thus
approximately 1.4 million t (including byproduct tungsten)
in MEC's only, and 2.9 million t worldwide.
Average 1980-82 levels of production were nearly 29,800
t of concentrate (W0 3 content) per year from MEC's and over
61,000 t/yr worldwide (see figure 3). At these rates of pro-
duction, demonstrated resources in MEC deposits evaluated
would last 46 yr.
For individual deposits and individual countries, the
ratio of demonstrated resources to current annual produc-
tion levels varies greatly. For example, China's estimated
average production from 1980 to 1982 was approximately
17,225 t/yr of W0 3 , Chinese deposits evaluated for this study
contain nearly 1.1 million t of recoverable W0 3 (based on
an assumed 70 pet recovery), giving it about 64 yr of pro-
duction at a rate of 17,225 of W0 3 per year. The estimate
for the U.S.S.R.'s production is 11,154 t/yr from 1980 to
1982. Its recoverable resources are approximately 433,000
t of W0 3 (assuming a 70-pct recovery), which means it can
continue to produce at that rate for about 39 yr. Within the
MEC's, Bolivia (with less than 6 yr of production available
from demonstrated resources at the average 1980-82 rate)
and Canada (with more than 120 yr of production at the
1980-82 rate possible from demonstrated resources) repre-
sent end points for the ratio of demonstrated resources to
annual production for deposits evaluated. The availability
discussions that follow will provide more detailed informa-
tion about the resources and annual production capacities
at the deposits in each country.
Scheelite Concentrate
This section discusses scheelite concentrates and ex-
cludes wolframite, even though the largest portion of con-
centrate traded may be wolframite. Although wolframite
concentrates are traded widely, they are of varying grades
and qualities and are generally further processed before
reaching a final consumer. Scheelite, by contrast, can be
a direct addition to a steel bath, usually requiring no fur-
ther processing. All wolframite concentrates (except for the
ferberite that is processed to ferrotungsten) were assumed
to be processed to APT in the cost evaluations.
In this analysis, scheelite processing is assumed to result
in a nearly homogeneous product from all mines. Natural
41
and artificial scheelite arc combined for study purposes even
though the relative sales price of the two commodities can
vary by a few percent, depending on market conditions and
the needs of consumers. The higher purity artificial
scheelite sometimes commands a premium, but tor the past
lew years scheelite has been in excess supply and the prices
have been approximately the same. High-quality natural
scheelite is produced at some mines, and for some uses the
generally higher molybdenum content of natural scheelite
is a desirable characteristic. In general, all scheelite con-
centrate are traded using a common reference price, with
the proviso that each property's output may be valued
slightly differently in the marketplace.
The grade of scheelite concentrates from the operations
evaluated varies from 70 to 75 pet. which means output from
all deposits fits the Metal Bulletin and International
Tungsten Indicator definitions of standard grade concen-
trates. However, there are differences in the chemical
makeup of each concentrate that may make it more or less
suited to a particular use. The actual price at which each
- traded depends on how well the marketer of
the concentrate is able to fulfill the needs of the customer.
>11 as the current conditions of the market.
Comparative prices should be interpreted carefully. Dif-
ferences between properties of a few percent in the
calculated average total costs have very little meaning.
Theiv s 1( _:ee of error inherent in all cost estimates and
some quality differences in the product of each mine. For
either of these reasons, an estimated cost could change by
a few percent. When comparisons to published prices are
made, the same caution should hold. These are only reported
prices, they have limited coverage, they are annual
averages, and they do not include penalties or premiums
that would be applied because of impurities or grade.
Eleven MEC deposits that do or would produce tungsten
as the primary product were evaluated under the assump-
tion that scheelite 'either natural or artificial) concentrate
is the first marketable product. Only those operations that
already market scheelite or that can reasonably be expected
to do so 'based on company information on marketing plans
or chemical analysis of the ore) were classified as scheelite
producer No U.S. properties were costed as scheelite
produ
Total Availability
Approximately 553.000 t of W0 3 is potentially
erable as scheelite (46 pet of total W0 3 available from
evaluated dei th most of the tonnage potentially
available from nonproducing deposits. Figure 28 shows the
tonnages available from the nine producing deposits
evaluated and the estimated average total cost of produc-
tion associated with each deposit. Two curves are shown —
the solid line represents results from the evaluations assum-
ing a 15-pct DCFKOR. the dashed line represents the results
at a 0-pct. or breakeven, rate. At this breakeven level of
costs, each property is able to recover all costs of produc-
tion, including payment of taxes and recovery of all capital
investments, but makes no rate of return on that
investment.
Approximately 142.000 t of WO, in scheelite concen-
trates is potentially available from producing deposits. At
a 15-pct DCFROR, average total costs of production range
from $2.30 to $6.05/lb, with the most of the tonnage
available at under $4 lb. The weighted-average total cost
of production for all scheelite producers is $3.33 lb of WO-,.
The range of estimated costs is much narrower at the 0-pct
DCFROR. with all properties having average total costs of
production of $5 lb of W0 3 or less. At a 0-pct DCFROR the
weighted average cost drops almost 20 pet. to $2.73 lb. and
more than 90 pet of the tonnage is available at costs below
the January 1983 market price of $3.63 /lb of W0 3 .
The range of tungsten concentrate prices (in January
1981 dollars) over the 1973 to 1983 period is given in table
18 (see table 1 for more complete information on historical
price trends). All of the producing properties shown in figure
28 have experienced years when market prices were higher
than estimated costs. Based on these evaluations, only in
1973. 1982, and January 1983 have prices been at a level
that would not return at least a 15-pct DCFROR for all pro-
ducing properties. Even at the low market price existing
in January 1983, three of the nine producers are still able
to make at least a 15-pct DCFROR.
By far the largest scheelite deposit evaluated is Mac-
tung, a nonproducing prospect located on the Yukon-
Northwest Territories border in Canada. The current
estimate of demonstrated resources is 412.700 t of
recoverable W0 3 , making it larger than all other scheelite
properties combined and also the largest MEC property
Table 18.— U.S. market price for tungsten concentrates,
constant January 1981 dollars per pound W0 3
1973
1974
1975
1976
1977
1978
Price
$5 00
1979
Price
$7 38
7.34
1980
6.87
7.09
1981
6.51
8.25
1982
4.88
11.42
January 1983
3.63
846
Period average
6.99
15-pcr DCFROR
O-pct DCFROR
j
I
I
^.J"
W03,l0 3 t
Figure 28— Total W0 3 potentially available from scheelite producers at 15-
and 0-pct DCFROR s.
42
evaluated. Mactung is the most expensive scheelite property
evaluated at a 15-pct DCFROR. Still, the relatively high
annual average prices such as existed in the mid-1970's
would be sufficient to return a full 15 pet on required in-
vestment at Mactung.
Estimated costs for the' nonproducers at a 0-pct
DCFROR are substantially lower than those from the 15-pct
DCFROR results, reflecting the effect of the required rate
of return on capital in the formation of a price expectation
by a deposit owner considering development. Properties
with the largest capital expenditures early in the life of the
property show the largest drop in average total costs
between a 15-pct DCFROR and a breakeven or 0-pct
DCFROR. This point is demonstrated dramatically with
reference to the Mactung property. Mactung, which will re-
quire very large capital investments and several years
development time before it can produce, shows more than
a 63-pct decrease in estimated cost, indicating that all
capital could be recovered, and a small profit is possible even
at relatively low market prices.
Annual Availability
Current producers can supply about 12,000 t of W0 3 in
scheelite concentrates annually when operating at full
capacity. Figure 29 illustrates that about 80 pet of this
amount is available from producers with average total costs
below $4/lb of W0 3 (at a 15-pct DCFROR). Based on
demonstrated resources only, this level of production can
be maintained through 1988, at which time output levels
could begin to drop fairly quickly. Barra Verde, Brazil, has
demonstrated resources sufficient to last only through 1986,
Kara, Australia, has resources to last through 1988, and
Brejui, Brazil, and Cantung, Canada, run out of currently
demonstrated resources in 1990. King Island, Australia, and
Sangdong, Republic of Korea, two of the major producers
at the present time, can continue to produce at current
levels from demonstrated resources until about the year
2000. However, the demonstrated resource figures used for
this evaluation could substantially understate the ultimate
production potential at many operations.
How well scheelite producers will be able to meet poten-
tial annual demand will be addressed in the "Tungsten
Availability— All Product Forms Combined" (annual
availability) section. No records are available from most
countries of the form in which tungsten is actually consum-
ed, and demand is generally reported as an aggregate
amount of W0 3 (or W) consumed in all forms. The final an-
nual availability subsection will discuss availability of all
forms of tungsten from all sources and make comparisons
with possible demand scenarios for all the tungsten products
combined.
The two nonproducers can potentially provide a substan-
tial supplemental source of scheelite. Zangarelhas could pro-
vide an average of over 400 t/yr of W0 3 in scheelite con
centrates if the Boca de Lage mine and concentrator expand
to include development of that portion of the ore body at
the production level assumed for this evaluation. The min-
ing plan assumed for the huge Mactung ore body models
production at more than 3,500 t of W0 3 per year. At this
rate Mactung could produce well beyond 2100.
Ammonium Paratungstate (APT)
Forty-one of the fifty-seven properties in this study were
evaluated as APT producers. Ore from any mine can be pro-
cessed into APT, and it is often the first standard product
form in which it is possible to make comparisons between
properties.
Total Availability
Approximately 633,000 t of W0 3 is potentially
recoverable as APT (52 pet of total W0 3 potentially
available from evaluated MEC deposits) from 26 producing
and 15 nonproducing deposits, with 146,000 t (23 pet) of that
amount available from 12 U.S. properties. Figure 30 shows
the tonnages available as APT, at a 15-pct DCFROR, from
all MEC deposits analyzed, as well as the amounts available
from U.S., South American, and European deposits.
Average total cost of production ranges from $0 to $21.00/lb
(January 1981 dollars) of W0 3 in APT after accounting for
byproduct credits. The weighted-average total cost of pro-
duction for all APT properties is $12.55/lb of W0 3 .
The range of APT prices (in January 1981 dollars) over
the 1973 to 1983 period is given in table 19 (see table 1 for
1 1
$6 06
Costs are in January 1981 dollars per
pound of WO3 m concentrate Costs
include a 15-pct DCFROR
_
-
$ 3 63
^^^ -
-
i '
\ "~"~ - ~~~— — — —
\^
; 1 !
YEAR
Figure 29.— Annual W0 3 potentially available from scheelite producers at
various average total costs.
43
— i 1
AvJiloMf from Un.tfd Stotts
-
AvO'loD'e tt o
< ?
KEY
■ 15-pct DCFROR
O-pct DCFROR
S
O 50 IOO 150 200 250 300 350 400 450
W0 3 , 103 t
Figure 32.— Total W0 3 potentially available from ammonium
paratungstate nonproducers at 15- and O-pct DCFROR's.
weighted-average cost equal to $15.45/lb of W0 3 . None of
the nonproducers can recover all costs of production (in-
cluding the 15-pct DCFROR) at the January 1983 market
price. However, at the average market price prevailing over
the last decade ($8.86/lb of W0 3 ), two properties appear able
to recover all costs. At the peak annual average price that
prevailed in 1977, 10 properties with 100,000 t of
recoverable W0 3 could recover all costs of production, in-
cluding the 15-pct DCFROR.
Estimated costs decrease more than 55 pet, on average,
when the nonproducing properties are evaluated with no
rate of return required on invested capital. The weighted
average total cost for nonproducers is $6.55/lb at a O-pct
DCFROR. At pet, about 25,000 t of W0 3 in APT is poten-
tially available from three nonproducers at costs below the
January 1983 market price ($5.37/lb). Almost 400,000 t of
W0 3 (96 pet of the total available from nonproducers) is
potentially available at costs below the average market
price prevailing over the last decade. At a 0-pct DCFROR,
all of the nonproducing APT properties have estimated
average total costs of production below the peak prices of
1977 and 1978. That is, all the nonproducers could make
a positive rate of return on investment if market prices
prevailed over the long run at levels equal to or greater than
the average annual prices in 1977 or 1978.
There are several very large deposits among the non-
producers, with the Logtung deposit in Canada being the
largest. Some potential cost savings measures, such as high
grading early in the life of these large deposits, have been
suggested in the mining literature but were not considered
in the costing. Since all of the nonproducers were costed
using estimated development schedules and current min-
ing and milling methods, these average total cost estimates
should be viewed with caution. The cost numbers are good
estimates of the potential profitability of the deposits given
current technology and our present understanding of the
physical characteristics of the respective ore bodies.
However, improved processing methods could improve the
economic outlook for any of the deposits by the time they
are actually developed.
Annual Availability
Potential annual availability of W0 3 in APT from pro-
ducing mines is shown in figure 33. Each line on the graph
reflects annual availability at or below different maximum
average total cost of production (including a 15-pct
DCFROR). About a third (5,000 t annually) of the tonnage
potentially available in the next 3 to 5 yr from current pro-
ducers is at average total costs (including a 15-pct DCFROR)
under $5.37/lb, approximately the January 1981 dollar
market price existing in January 1983. Most of the tonnage
(14,000 1 annually) is available at less than the average an-
nual price over the last decade ($8.86/lb of W0 3 ). In total,
there is nearly 16,000 t/yr of W0 3 in APT potentially
available through the decade of the 1980's at costs rang-
ing up to $12.66/lb of W0 3 .
After 1986, annual production from demonstrated
resources could begin to decline rather quickly and by 1995
projected production from current producers is less than half
what it was at the peak. There are two reasons why the
decline may be less than shown in these curves. First, the
current weak market for tungsten means some operations
will be producing at less than full capacity over the next
few years. Second, some of the deposits, notably the Boli-
vian deposits, are likely to have resources in excess of the
current demonstrated level.
45
5
Costs ore in Januoty 1981 dollars per
pound of WO3 in APT Costs include
'6
a 15- pet DCFROR
14
-^S8 86-,
12
-
. ^-—-^$700
O
§ s
6
$5 37
•i
^
2
1 1 1 1
986 S87 988 1989 1990 1991 1992 1993 1994 1995
YEAR
Figure 33.— Annual W0 3 potentially available from ammonium paratungstate
producers at various average total costs.
The amount of tungsten potentially available annually
from deposits not yet producing is shown in figure 34. The
pattern of annual availability reflects the set of assump-
tions that went into the evaluation concerning the speed
with which different deposits could develop. Each property
was developed with the minimum necessary engineering
and construction time allowed for, and no provision was
made for gathering required permits, arranging financing,
etc. A near maximum level of production from deposits not
yet developed is forthcoming about 4 to 6 yr after the deci-
sion to begin development. The pattern is similar at all cost
levels displayed.
Less than 1.000 t of annual capacity is available from
nonproducers at costs below the constant dollar average an-
nual price of the last decade ($8.86flb of W0 3 ). About 3,500
t of annual capacity is potentially available at costs at or
below the peak annual average price of 1977 ($13.48/lb of
W0 3 ). The bulk of potential annual production from non-
producing APT operations would require prices higher than
have been experienced in the past in order to recover all
costs of production, including a 15-pct DCFROR.
Ferrotungsten
Five properties were evaluated in this study under the
assumption that ferrotungsten is the first marketable prod-
uct. All these properties have ferberite as the main ore
mineral. Three of the properties are current producers of
ferrotungsten, and the other two are past producers of ferro-
tungsten. Khao Soon, Thailand, was shut down in 1975
- dollars per
pound 0+ W0 3 in APT Costs include
15-pcT DCFROR
1 T"- -
N Yew preproduction developrrent begins
S2 .^-^~~^~^
/ il348_—
/ /
-
^y /^
.
1 '
-. .-
N+IS
Figure 34.— Annual W0 3 potentially available from ammonium paratungstate nonproducers at
various average total costs
46
(after several years of production) due to chaotic political
conditions. Nyamalilo, Uganda, has had intermittent pro-
duction for more than 20 yr, always at a low level, but has
not operated for the past several years.
Total Availability
Figure 35 illustrates total availability of ferrotungsten
at different levels of average total costs of production. Two
curves are shown in the figure. The solid line illustrates
the results from the evaluation assuming a 15-pct DCFROR,
while the dashed line illustrates the results with a 0-pct
DCFROR. Approximately 16,400 t of W is potentially
recoverable as ferrotungsten (2 pet of total MEC tungsten
available). Estimated average total costs at a 15-pct
DCFROR range between $4.35 and $15.30/lb of W, with the
weighted-average total cost for all ferrotungsten properties
equal to $7.40/lb of W. The three current producers (with
a weighted-average total cost of $8.30/lb of W) account for
over 25 pet (4,200 t) of the total tonnage. A separate graph
for ferrotungsten producers is not provided because of the
small number of operations. Most of the total (11,000 t) is
potentially available from Khao Soon, Thailand, currently
shut down because of political conditions.
The market price used as a reference price in this sec-
tion is in terms of its W content only (W content = 0.793
x W0 3 content). The formula for the computed price was
given in the "Tungsten Pricing" section of this report, and
is based on the market price for concentrate plus a conver-
sion charge. Table 20 gives the computed average annual
ferrotungsten prices in January 1981 dollars from 1973 to
January 1983, including the average price over the entire
period.
It should be remembered that every mine's output has
a unique chemical makeup that will make its selling price
unique, and comparisons of average total costs to historical
sales prices are made for reference purposes only.
At a 15-pct DCFROR, only one property has average
total costs below the 1983 market price. However, four of
the five properties have average total costs below the
average price (January 1981 dollars) of $9.98/lb of W that
has prevailed over the last decade.
At a 0-pct DCFROR, costs range between $3.20 and
$14.55/lb, with the weighted-average total costs of produc-
tion at pet equal to $4.60/lb of W. This 38 pet cost dif-
ference from the 15-pct results emphasizes the importance
of capital investments in total costs for these current pro-
ducers and past producers. Those properties with relatively
large investments or a long development time show the
Table 20.— U.S. market price for ferrotungsten, constant
January 1981 dollars per pound of tungsten
< 2>
1 1 1 1
KEY
— i 1 1
i
- 15-pct DCFROR
-
0-pct DCFROR
-
-
-
-
-
i
-
i i i i i . _i 1
Price
1973 $7.40
1974 10.45
1975 10.12
1976 11.63
1977 15.75
1978 11.93
Price
1979 $10.52
1980 9.84
1981 9.37
1982 7.24
January 1983 5.61
Period average 9.98
W,l0 3 t
Figure 35. — Total W potentially available from ferrotungsten
deposits at 15- and 0-pct DCFROR's.
greatest reduction in development costs when evaluated at
pet. Where mine and mill operating costs are high, and
little capital investment is needed, the estimated average
total cost of production drops very little when the required
rate of return is reduced from 15 to pet.
Annual Availability
Approximately 400 1 of W is available in ferrotungsten
annually from current producers operating at capacity.
However, all the present producers except Doi Ngoem will
have exhausted their demonstrated resources by 1990.
Nyamalilo could develop quickly (2 to 3 yr) and would add
up to 170 t annually of W in ferrotungsten. Khao Soon could
take much longer to develop for two reasons: the physical
deterioration of the mine and the facilities since its closure
in 1978, and the troubled political climate inhibiting invest-
ment. If Khao Soon does develop it could add nearly 700
t/yr of W to the market, and there are sufficient
demonstrated resources to continue production at that rate:
for about 20 yr.
No information is available regarding the potential for
additional resources at Borralha (Portugal) and Cham-
billaya (Bolivia), but it is possible that both properties could
have several years' additional production beyond the<
demonstrated resource level evaluated. Borralha is a small
operation that expends little effort to define resources
beyond the next few years' requirements. The exploration
philosophy at Chambillaya, as with most of the Bolivian
operations, is to develop only enough information to sup-
port the next few years' production.
TUNGSTEN AVAILABILITY— ALL PRODUCT
FORMS COMBINED
Tungsten availability has been discussed in the three
previous sections in terms of scheelite concentrate, APT,
or ferrotungsten. This section brings together all product
forms and discusses the availability of tungsten as a single
commodity. It also includes a brief discussion of the avail-
ability of tungsten from alternative sources, such as CPEC
deposits, stockpiles, scrap, and as byproduct tungsten from
other mines. The section concludes by relating annual
availability to annual consumption, based on estimated
trend projections of demand.
Total Availability
MEC primary tungsten deposits evaluated in this study
have demonstrated resources of approximately 1.2 million
t of recoverable W0 3 . Of this total, 46 pet (553,000 1) is poten-
tially available as scheelite concentrates, 53 pet (63,000 t)
as APT, and 1 pet (16,400 t W or 20,680 t W0 3 equivalent)
is potentially available as ferrotungsten. At current rates
of production (the 1980 to 1982 average MEC production
was nearly 29,800 t/yr of W0 3 ) these demonstrated resources
would last about 40 yr. However, with much of the tonnage
contained in a small number of large deposits, this may be
a misleading indicator of the ability of the MEC's to pro-
vide tungsten on an annual basis. The annual availability
discussion in this section will examine remaining resources
and annual capacities on a mine-by-mine basis.
China and the U.S.SJR. combined have total estimated
in situ demonstrated resources of nearly 2.2 million t of
\V0 3 . Assum. j rati' and continuation of
the average 19S0-S2 rate of production (17.225 t yr for
^hinahas64yrofpro-
n. the U.S.S.R. can produce for a 9 yr from
deposits evaluated. Discussion of capacity-resource infor-
mation on a mine-by-mine basis for CPEC deposits is in-
cluded in the "Geology and Resources" section. Lesser
amounts of tungsten are available from the rest of the
CPEC's. The Bureau regularly reports production from
Czechoslovakia and North Korea, for instance, but very lit-
tle of this tungsten reaches western markets. The Bureau
imates a reserve base for other CPEC's of 250 million
lb of W (equivalent to 143.000 t of W0 3 >.
The U.S. Government's stockpile contains more than
1 yr ofMEC consumption at recent levels, but most of this
inventory is needed to meet the stockpile goal. The excess
tungsten in the stockpile is generally offgrade, although
stockpile sales of tungsten could still impact the market in
the future. Producer and consumer stockpiles also exist, but
very little data are available concerning them. Privately
held U.S. stocks are reported annually in the Bureau's
Minerals Yearbook and have generally been between 20 and
40 pet of U.S. annual consumption levels.
Recycling has been a fairly constant source of tungsten
in the past, generally accounting for slightly less than 15
pet of consumption. The opportunities for recycling have
been expanded as tungsten carbide tools have become a
larger share of the market, and scrap could increase in im-
portance somewhat as a component of supply in the future.
Byproduct tungsten is also an important component of
supply, but is very difficult to measure or to forecast. The
United States, for example, has two large potential
byproduct sources— the Climax molybdenum mine in Col-
orado and the Searles Lake brine deposit in California. The
Climax Mine contains more than 100,000 t of W0 3 . It has
been the largest domestic tungsten source in past years
when the mine was operating at full capacity, producing
about 1.000 tyr of W0 3 in concentrates. However, the mine
is currently closed owing to the weak market for
molybdenum. A resumption of tungsten shipments from
Climax will await the recovery of the molybdenum market,
and has almost no relation to the state of the tungsten
market.
The Searles Lake deposit has about 77,000 1 of contained
WO, in brines. A process for recovering the tungsten has
been developed, but substantial investments would be re-
quired before recovery is possible. As with any untried
technology, tungsten recovery at Searles Lake remains an
unknown until such time as the investments are made and
the process is operational. The amount of tungsten
recovered annually will depend on conditions in the soda
ash market, and not on the tungsten market.
The source and amount of byproduct tungsten from out-
side the Unit* - rficult to estimate. Country pro-
duction data do not generally distinguish between primary
and byproduct tu- ran lead-zinc-
silver operatr mall amounts of tungsten. The
Naica mine is perhaps the largest Mexican tungsten
byproduct source, recovering about 245 t of W0 3 in 1981.
Many tin deposits in southeast Asian countries such as
Burma. Malaysia, and Thailand contain small amounts of
recoverable tungsten. The Nok Hoog tin mine in Malaysia,
for example, produces nearly 150 t of W0 3 per year.
Molybdenum deposits in the Republic of Korea contain
tungsten in recoverable amounts, but the total amount of
byproduct tungsten is insignificant in comparison to the
Sangdong operation.
The total amount of byproduct tungsten entering the
! tedly impo^ant but currently is recovered
from a large number of sources, and is difficult to account
for. The amount of byproduct tungsten entering the market
is a function of conditions in the markets for other primary
products. The costs of producing byproduct tungsten do not
appear to be a major factor at operations that are known
to currently be recovering byproduct tungsten, but with the
possibility of rising prices in the future, more operations
could choose to recover the tungsten available as a
byproduct. Little data are available with which to make
projections as to the likely future importance of byproduct
tungsten.
The principal source of tungsten production in the world
is likely to be the nearly 100 mines and deposits that do
or would produce tungsten as the primary product. Nearly
half of primary tungsten production currently originates
from MEC's. Both MEC and CPEC sources could potentially
produce more than they do now, although increases in price
might be required to compensate for the increased costs of
production if new MEC deposits have to be brought into pro-
duction. Among CPEC sources, China is the most likely to
expand production, either from existing mines or the
development of new mines. This would reduce the upward
pressure on price and delay the development of new MEC
properties.
Annual Availability
Over 30 pet (373,000 t of W0 3 ) of total tungsten poten-
tially available from evaluated MEC deposits is available
from current producers. At current rates of production, pro-
ducing deposits have an average of 14 yr of production left.
Demonstrated resources remaining at different producing
deposits in different countries show anywhere from 4-yr
potential production (at some of the Bolivian deposits) to
almost 40-yr production (at Barruecopardo, Spain). While
it is possible that further exploration will define additional
resources at some producing deposits (e.g., see the "Geology
and Resources" section of this report for a discussion of the
potential for additional resources at Bolivian deposits), it
appears likely that one or more nonproducing deposits could
be developed within the next 10 yr.
The following analysis compares annual availability
from current producers to projected annual demand in order
to estimate the adequacy of MEC production capacity in
meeting MEC demand. Because country production
statistics do not generally distinguish between tungsten
derived from primary sources and tungsten made available
from other sources, the assumption was made for this
analysis that the primary tungsten operations evaluated
in this study will supply 90 pet of projected MEC demand
'for as long as demonstrated resources last). This assumed
production level is attainable, since combined capacity at
all evaluated producing primary tungsten deposits in MEC's
is equal to greater than 90 pet of the peak production level
of 1980 (figs. 2-3). Byproduct and otherwise unaccounted for
48
tungsten production capacity (e.g., tungsten smuggled out
of Malaysia and Thailand or production from small mines
not evaluated) would make up the remainder of potential
annual supply.
Two alternative growth rates were used to project de-
mand between 1983 and 1995: 3.5 and 2.0 pet per year. The
3.5-pct growth rate was suggested in the tungsten chapter
of the 1980 Mineral Facts and Problems (8). The 2.0-pct rate
is included as a sensitivity analysis in light of the poor per-
formance of the world's economies in recent years. Only
present operating capacities and known planned expansions
that were part of the proper* y evaluations are assumed to
be available to fill that demand, and new mines will be
developed as needed to keep MEC supply and demand in
balance. All current producers were assumed to continue
producing at capacity until all demonstrated resources are
exhausted.
The major element excluded from this scenario is China.
With the world's largest known resources (China can con-
tinue to produce at current rates from known resources for
more than 60 yr), China could expand production and limit
the number of new operations required, or reduce tungsten
shipments and put upward pressure on price. The assump-
tion was made that the current situation, with MEC supply
approximately equal to MEC demand, will continue to hold
in the future as it has for the last 10 yr (see figure 3).
Figure 36 shows annual availability from all current
MEC producers combined, without reference to price. The
straight lines show simple trend projections of potential de-
mand for tungsten in MEC's, calculated as either a 3.5- or
a 2.0-pct growth rate after 1984. All demand projections
shown are for 90 pet of the total MEC demand to facilitate
comparison with the annual availability curve. Since
preliminary data for 1983 indicate MEC consumption is ab-
normally low (as was 1982— see table 3), several assump-
tions were made concerning what would be "normal" de-
mand in future years. For this analysis, 1983 consumption
is assumed equal to 1982's, and 1984 consumption is as-
sumed to return to the level of 1981. Consumption levels
for 1985 and beyond are calculated as a fixed percentage
growth per year from the 1984 base.
As seen in figure 36, current producers can supply more
than the amount required for the next 4 to 5 yr. If excess
production capacity in the 1983-86 period leads to reduced
levels of production, then the producing lives at some cur-
rent operations will be extended and will offset apparent
production shortfalls in the 1987-88 period. By 1989 or 1990,
however, several of the nonproducers may need to be
developed. There are five nonproducers whose estimated
average total costs of production are lower than the average
market prices prevailing over the past decade. They could
begin production by 1990 to correspond with projected in-
creases in demand. If developed, they will add about 2,400
t of W0 3 annual capacity.
After 1990 there could be a rapid dropoff in availabil-
ity from current producers. The Cantung deposit in Canada,
for instance, will be depleted of currently reported
demonstrated resources by 1991. Also depleted by 1990 are
all but three of the Bolivian deposits (a drop of 2,300 t
annual capacity) and two of three Brazilian deposits (1,000
t annual capacity). Mawchi, Pasto Bueno, Kara, Borralha,
and Strawberry could also have exhausted their currently
demonstrated resources by 1990. It has been emphasized
in previous sections of this report that many of the current
producers might have resources larger than the
demonstrated level used in the evaluations, but this is
uncertain and new property development could be required
by about 1990.
AMAX has performed preliminary engineering and
evaluation studies on the Mactung (Canada) property, which
is estimated to be the lowest cost of the large nonproduc-
ing properties evaluated. Mactung would add more than
3,500 t of W0 3 annually if it is developed at the capacity
assumed for the evaluation. The estimated average total
cost of production at Mactung is higher than the average
annual price for scheelite has been over the last decade, but
still below the peak annual average prices of 1977-78.
Throughout the 1990's total availability from current
40
38 -
36
34
32
30
28
26
24
22
20
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995
YEAR
Figure 36.— Annual MEC W0 3 availability and projected demand, 1983-95.
49
producers could continue as currently demonstrated
urces are depleted. According to the evaluation results.
Panasquiera (Portugal) has demonstrated resources to last
only through 1994. Mittersill Austria", is depleted of
demonstrated resources in 1H94. and Yxsjoberg (Sweden),
eported demonstrated resources to last only through
1995 i assuming full capacity levels of production". If addi-
tional res - ire not found at some of those currently
producing deposits, then more of the nonproducers may
have to be developed.
The Pilot Mountain. Thompson Creek, Indian Springs,
and Queen properties in the L'nited States all
nated average total costs below past peak prices.
Their combined annual capacity would be nearly 2.600 t
of WO* Other properties with estimated average total costs
below past peak prices are located in Mexico. Namibia,
Thailand, aid Uganda. Combined annual capacities from
all nonproducers with average total costs of production
below past peak prices is about 9.400 t of W0 3 .
If current produ not extend their reserves (and
therefore their producing lives) beyond the demonstrated
resource level used in these evaluations, then by the
mid-1990s some of the more costly deposits may have to
be developed. Nearly 7.600 t of annual W0 3 production
capacity would be available from six nonproducers (all
evaluated as APT properties" with estimated average total
rid $21.00 lb of W0 3 . For any of these
properties to develop, there will have to be an expectation
of higher prices than have prevailed in the past.
There are many factors that could allow a longer-term
supply-demand balance than is indicated by the availabil-
-dy results. Principal among these is the possibility
of expanding the resource base at some of the properties.
For many of the deposits, lower grade resources or satellite
ore bodies are known to exist, but have not been defined
at the demonstrated level. A second possibility is that new
producers could develop at annual capacities larger than
those used in the evaluations. Mactung certainly has
enough resources to support a capacity larger than assum-
ed for evaluation purposes, but the capacity AMAX chooses
to develop the property at will partially depend on the
market situation existing at that time.
Also of major importance to the future supply-demand
balance is the possibility of expansion or contraction of
Chinese exports to the MEC's. An expansion of exports
could delay the development of new producers for many
years (or even cause some of the higher cost current pro-
ducers to shut down), while a contraction of exports would
put immediate upward pressure on price and spur
development.
In the absence of major expansions of tungsten produc-
tion and exports by the Chinese, it appears clear that an
emphasis on exploration is warranted. Whether that ex-
ploration focuses on extending currently known ore bodies
or attempts to locate new ore bodies, this investigation sup-
ports the idea that low-cost ore bodies can probably be
developed in the 1990's to replace other properties whose
resources are being depleted.
If prices do rise because of higher costs at newly
developed operations, this would be an incentive for more
scrap recycling. Another possible response to higher market
prices (if they occur) is expanded byproduct tungsten sup-
plies, but there are little data available concerning the
amount of tungsten not presently recovered.
Lastly, there is the possibility that there will be ad-
justments in potential demand. If higher prices or availabil-
ity become a problem, some substitutions away from
tungsten could be made, reducing the need for new proper-
ty development. It is also possible that demand growth could
be much lower than the rates assumed for this analysis.
If there is no growth in demand from 1982-83 levels, cur-
rent producers could supply the market until nearly 1995
from currently demonstrated resources. In fact, some of the
current producers appear to be operating at a loss with cur-
rent market prices (based on the results of the evaluations)
and might be forced to close temporarily if there is no
growth in tungsten demand.
CONCLUSIONS
At the demonstrated resource level, the 57 deposits and
properties in 19 MEC's contain an estimated 1.2 million
t of recoverable WO„ of which more than 30 pet (373,000
from producing mines or temporarily shut down opera-
The remainder is from deposits that have either never
produced or would require large capital investments to once
again become producing properties. Canada has the largest
recoverable demonstrated resources among the MEC's, with
53 pet of the total. The United States and Australia account
for 12 and 9 pet, respe. total recoverable WO,
in MEC deposits evaluated.
nstrated recoverable resources in
MK ' 'entially available as WO,
in Al ie total amount available as APT. 35 pet
'219 romproducir pet of the
total amount of recoverable V\ I nlable as
APT is contained in the largi i d Logtung deposit
in Canada.
More than 7 pet of the total WO ,1,1.- from all
uated a^ APT - potentially
available at or below an average total lb of
WO„ which was the January 1983 market price of APT.
The weighted-average total cost for APT producers is
$7.10/lb, and the weighted-average total cost for all proper-
ties evaluated as APT operations is $12.55/lb.
Approximately 553,000 t of recoverable W0 3 is poten-
tially available as high-grade natural or artificial scheelite,
26 pet (142,000 t) from producers. Seventy-two percent is
contained in the (nonproducing) Mactung, Canada, deposit.
Sixteen percent of the total recoverable W0 3 in all
deposits evaluated as scheelite operations is potentially
available at or below an average total cost of $3.63/lb of
WO„ which was the January 1983 market price for
tungsten concentrate. Nearly two-thirds of the W0 3
recoverable at or below that cost is from the Sangdong
operation in the Republic of Korea. The weighted-average
total cost for scheelite producers is $3.33/lb of W0 3 , and for
all scheelite properties combined it is $7.05/lb.
About 16,400 t of recoverable W (20,700 t equivalent
W0 8 ) i pot* otially available as ferrotungsten, 26 pet from
producers Seventy seven percent of the total W recoverable
as ferrotungsten is from deposits in Thailand.
50
At an average total cost of $5.61 lb of W in ferrotungsten
uhe January 1983 market price in terms of January 1981
dollars». only one property. Doi Ngoem in Thailand, can
realize a 15-pct rate of return. This deposit accounts for 10
pet of the total amount of \V available from all deposits
evaluated as ferrotungsten properties. The weighted-
average total cost for all ferrotungsten producers is $8.30 lb
ofW.
A U S. deposits were evaluated with APT as the
primary final product. There is approximate v 146.000 t (23
pet of the total tonnage from all deposits e\ aluated as APT
producers" of recoverable WO, potentially available from
- deposits. Less than 3 pet of recoverable \V0 3 in APT
from U.S. deposits is potentially available at an average
total cost of $5.37 lb of \VO : , or less uhe January 1983
market price 1 : an additional 8 pet of the total is available
at costs up to $7.00 lb. The weighted-average total cost of
APT producers in the United States is $7.75 lb. and for all
S properties evaluated the weighted-average total cost
-'.301b.
The United States is likely to continue to rely on im-
ports for a substantial portion of its tungsten consumption.
If all evaluated U.S. properties were to produce at assumed
full capacity levels, total annual production would be only
6,000 to 7.000 t of recoverable WO„ which is equivalent
to approximately 60 to 70 pet of estimated reported average
U.S. consumption over the 1980 to 1982 period.
This analysis indicates that the amount of tungsten
potentially available from producing MEC deposits
evaluated could be substantially less than consumption by
the early 1990's owing to depletion of currently
demonstrated resources. If additional demonstrated
resources are not defined at producing operations, then the
consumption-production gap will need to be filled either by
development of evaluated nonproducers, development of cur-
rently unknown deposits, or increased exports from China.
Owing to its large tungsten resource (40 pet of the total
recoverable W0 3 in all deposits examined), China has the
potential to become an increasingly important factor in the
world tungsten supply-demand picture. At estimated 1982
production levels, China has sufficient demonstrated
resources to last for more than 60 yr. The U.S.S.R., with
an estimated 433,000 t of recoverable W0 3 ( 16 pet of the
total in all deposits examined), will likely continue to be
a net tungsten importer and could have an important future
effect on the demand side of the world supply-demand
relationship.
51
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