S \LUnO\S GfOLOGICAfc ^212 SURVEY LIBRARY c. 3 ~ » „ x ■■-•* OF ILLINOIS William G. Stratton, Governor DEPARTMENT OF REGISTRATION AND EDUCATION Vera M. Binks, Director 1959 ACIDIC STRUCTURAL GROUPS IN ILLINOIS COALS: Variation During Oxidation and Carbonization T. P. Maher J. M. Harris G. R. Yohe REPORT OF INVESTIGATIONS 212 ILLINOIS STATE GEOLOGICAL SURVEY JOHN C. FRYE, Chief URBANA, ILLINOIS ACIDIC STRUCTURAL GROUPS IN ILLINOIS COALS: Variation During Oxidation and Carbonization T. P. Maher J. M. Harris G. R. Yohe Illinois State Geological Survey Report of Investigations 212 Urbana, Illinois 1959 PRINTED BY AUTHORITY OS THE STATE OF ILLINOIS STATE OF ILLINOIS HON. WILLIAM G. STRATTON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION HON. VERA M. BINKS, Director BOARD OF NATURAL RESOURCES AND CONSERVATION Hon. Vera M. Binks, Chairman Walter H. Newhouse, Ph.D., Geology Roger Adams, Ph.D., D.Sc, Ll.D., Chemistry Robert H. Anderson, B.S., Engineering Alfred E. Emerson, Ph.D., Biology Lewis H. Tiffany, Ph.D., Pd.D., Forestry Dean William L. Everitt, E.E., Ph.D., University of Illinois President Delyte W. Morris, Ph.D., Southern Illinois University GEOLOGICAL SURVEY DIVISION JOHN C. FRYE, Ph.D., D.Sc, Chief (89764—2,500—12-58) STATE GEOLOGICAL SURVEY DIVISION Urbana, Illinois. FULL TIME STAFF Enid Townley, M.S., Geologist and Assistant to the Chief JOHN C. FRYE, Ph.D., D.Sc, Chief M. M. Leighton, Ph.D., D.Sc, Chief, Emeritus Helen E. McMorris, Secretary to the Chief Velda A. Millard, Junior Assistant to the Chief GEOLOGICAL GROUP M. L. Thompson, Ph.D., Principal Geologist Arthur Bevan, Ph.D., D.Sc, Principal Geologist, Emeritus Frances H. Alsterlund, A.B., Research Assistant COAL Jack A. Simon, M.S., Geologist and Head G. H. Cady, Ph.D., Senior Geologist and Head, Emeritus Robert M. Kosanke, Ph.D., Geologist John A. Harrison, M.S., Associate Geologist Paul Edwin Potter, Ph.D., Associate Geologist William H. Smith, M.S., Associate Geologist Kenneth E. Clegg, M.S., Assistant Geologist Margaret A. Parker, M.S., Assistant Geologist David L. Reinertsen, A.M., Assistant Geologist OIL AND GAS A. H. Bell, Ph.D., Geologist and Head Virginia Kline, Ph.D., Associate Geologist Lester L. Whiting, M.S., Associate Geologist Wayne F. Meents, Associate Geological Engineer Margaret O. Oros, B.A., Assistant Geologist Thomas W. Smoot, M.S., Assistant Geologist Jacob Van Den Berg, M.S., Assistant Geologist Richard H. Howard, M.S., Research Assistant Ronald A. Younker, B.S., Research Assistant PETROLEUM ENGINEERING Carl W. Sherman, M.S., Petroleum Engineer and Head INDUSTRIAL MINERALS J. E. Lamar, B.S., Geologist and Head Donald L. Graf, Ph.D., Geologist James C. Bradbury, Ph.D., Associate Geologist James W. Baxter, Ph.D., Assistant Geologist Meredith E. Ostrom, M.S., Assistant Geologist PHYSICS R. J. Piersol, Ph.D., Physicist, Emeritus CLAY RESOURCES AND CLAY MINERAL TECHNOLOGY W. Arthur White, Ph.D., Geologist and Head Walter E. Parham, M.S., Assistant Geologist GROUNDWATER GEOLOGY AND GEOPHYSI- CAL EXPLORATION George B. Maxey, Ph.D., Geologist and Head Merlyn B. Buhle, M.S., Geologist Robert E. Bergstrom, Ph.D., Associate Geologist James E. Hackett, Ph.D., Associate Geologist Grover H. Emrich, M.S., Assistant Geologist John P. Kempton, M.A., Assistant Geologist Wayne A. Pryor, M.S., Assistant Geologist Lowell A. Reed, B.S., Research Assistant Margaret J. Castle, Assistant Geologic Draftsman (on leave) ENGINEERING GEOLOGY AND TOPOGRAPHIC MAPPING George E. Ekblaw, Ph.D., Geologist and Head William C. Smith, M.A., Assistant Geologist STRATIGRAPHY AND AREAL GEOLOGY H. B. Willman, Ph.D., Geologist and Head Elwood Atherton, Ph.D., Geologist David H. Swann, Ph.D., Geologist Charles W. Collinson, Ph.D., Associate Geologist Herbert D. Glass, Ph.D., Associate Geologist John A. Brophy, Ph.D., Assistant Geologist T. C. Buschbach, M.S., Assistant Geologist Robert W. Frame, Supervisory Technical Assistant Romayne S. Ziroli, Technical Assistant Joseph F. Howard, Assistant CHEMICAL GROUP Grace C. Finger, B.S., Research Assistant PHYSICAL CHEMISTRY J. S. Machin, Ph.D., Chemist and Head Neil F. Shimp, Ph.D., Associate Chemist Daniel L. Deadmore, M.S., Assistant Chemist Juanita Witters, M.S., Assistant Physicist ANALYTICAL CHEMISTRY O. W. Rees, Ph.D., Chemist and Head L. D. McVicker, B.S., Chemist Emile D. Pierron, Ph.D., Chemist William J. Armon, M.S., Assistant Chemist Francis A. Coolican, B.S., Assistant Chemist Effie Hetishee, B.S., Research Assistant John K. Kuhn, Research Assistant Steven Pusztaszeri, Research Assistant Samiha Ragab, M.S., Research Assistant George R. James, Technical Assistant Benjamin F. Manley, Technical Assistant X-RAY W. F. Bradley, Ph.D., Chemist and Head COAL CHEMISTRY G. R. Yohe, Ph.D., Chemist and Head Joseph M. Harris, B.A., Research Assistant CHEMICAL ENGINEERING H. W. Jackman, M.S.E., Chemical Engineer and Head R. J. Helfinstine, M.S., Mechanical and Adminis- trative Engineer B. J. Greenwood, B.S., Mechanical Engineer Robert L. Eissler, M.S., Assistant Chemical Engineer James C. McCullough, Research Associate (on leave) Walter E. Cooper, Technical Assistant John P. McClellan, Technical Assistant Edward A. Schaede, Technical Assistant FLUORINE CHEMISTRY G. C. Finger, Ph.D., Chemist and Head Laurence D. Starr, Ph.D., Associate Chemist Donald R. Dickerson, B.S., Assistant Chemist Richard H. Shiley, M.S., Research Assistant MINERAL ECONOMICS GROUP W. H. Voskuil, Ph.D., Principal Mineral Economist Hubert E. Risser, Ph.D., Mineral Economist VV. L. Busch, A.B., Associate Mineral Economist ADMINISTRATIVE GROUP EDUCATIONAL EXTENSION George M. Wilson, M.S., Geologist and Head Ira E. Odom, M.S., Assistant Geologist Betty J. Hanagan, M.S., Research Assistant GENERAL SCIENTIFIC INFORMATION Autumn B. Fulton, A.B., Technical Assistant Joan Sevon, B.A., Technical Assistant PUBLICATIONS Dorothy E. Rose, B.S., Technical Editor Meredith M. Calkins, Geologic Draftsman Betty M. Lynch, B.Ed., Assistant Technical Editor Janice Schuetze, Assistant Geologic Draftsman Donna R. Wilson, Assistant Geologic Draftsman MINERAL RESOURCE RECORDS Vivian Gordon, Head Hannah Fisher, Supervisory Technical Assistant Kathryn L. Gronberg, B.S., Research Assistant Patricia Bielefeld, Technical Assistant Sandra H. Hoard, B.S., Technical Assistant Barbara L. Scott, B.A., Technical Assistant Elizabeth Speer, Technical Assistant Lucretia Stetler, B.A., Technical Assistant Danguole Tan, B.S., Technical Assistant TECHNICAL RECORDS Berenice Reed, Supervisory Technical Assistant Judith Flach, Technical Assistant Miriam Hatch, Technical Assistant LIBRARY Oltve B. Ruehe, B.S., Geological Librarian Carol S. Madden, B.A., Technical Assistant FINANCIAL RECORDS Velda A. Millard, In Charge Virginia C. Sanderson, B.S., Clerk IF Marjorie J. Hatch, Clerk-Typist III Joan P. Roseman, Clerk-Typist II Janice Schulthes, Clerk-Typist I * Divided time Topographic mapping in cooperation United States Geological Survey- November 16, 1958 SPECIAL TECHNICAL SERVICES William Dale Farris, Research Associate Beulah M. Unfer, Technical Assistant A. W. Gotstein, Research Associate Glenn G. Poor, Research Associate* Gilbert L. Tinberg, Technical Assistant Wayne W. Nofftz, Supervisory Technical Assistant Donovon M. Watkins, Technical Assistant Mary Cecil, Supervisory Technical Assistant Nancy A. Anvari, Technical Assistant Ruby D. Frison, Technical Assistant Alison Helmich, Technical Assistant CLERICAL SERVICES Mary M. Sullivan, Clerk-Stenographer III Rita J. Nortrup, Clerk-Stenographer II Anita F. Roosevelt, Clerk- Stenographer I Edna M. Yeargin, Clerk-Stenographer I Dorothy J. Gerdes, Clerk-Typist I Ann Vriner, Clerk-Typist I Leona W 7 hitesell, Clerk-Typist I William L. Mathis, Messenger-Clerk II Joseph R. Evans, Messenger-Clerk I AUTOMOTIVE SERVICE Glenn G. Poor, In Charge* Robert O. Ellis, Automotive Shop Foreman David B. Cooley, Automotive Mechanic Everette Edwards, Automotive Mechanic with the RESEARCH AFFILIATES Douglas A. Block, M.S., Wheaton College J Harlen Bretz, Ph.D., University of Chicago S. E. Harris, Jr., Ph.D., Southern Illinois University M. M. Leighton, Ph.D., D.Sc, Geological Survey A. Byron Leonard, Ph.D., University of Kansas Carl B. Rexroad, Ph.D., University of Houston Walter D. Rose, B.S., University of Illinois Paul R. Shaffer, Ph.D., University of Illinois Harold R. Wanless, Ph.D., University of Illinois Paul A. Witherspoon, Ph.D., University of Cali- fornia Frederick D. Wright, M.S., University of Illinois CONSULTANTS George W. White, Ph.D., University of Illinois Ralph E. Grim, Ph.D., University of Illinois CONTENTS Page Introduction 9 Acknowledgments 10 Procedures 10 Collection of samples 10 Sampling 10 Oxidation 11 Carbonization 11 Fine grinding 12 Titrations 12 Infrared studies ... 15 Results and discussion 15 Total acidity and component acidities 15 Acidic oxygen 15 Sample M, No. 6 Coal from Knox County 15 Fresh coal 16 Naturally oxidized coal 18 Forced oxidized coal 20 Infrared spectra 23 Sample N, No. 6 Coal from Jefferson County 25 Fresh coal 25 Naturally oxidized coal 28 Forced oxidized coal 30 Infrared spectra 33 Sample O, No. 5 Coal from Gallatin County 35 Fresh coal 35 Naturally oxidized coal 37 Forced oxidized coal 39 Infrared spectra 41 Sample P, Pocahontas Coal from West Virginia 45 Fresh coal 45 Naturally oxidized coal 47 Forced oxidized coal 48 Infrared spectra 51 Sample Q, Willis Coal from Gallatin County 52 Titration experiments 52 Rise in E. M. F. before titration 52 Residual acidity at 550° and 600° C 52 Caustic solubilities of the fresh and oxidized coals 53 Relation of the acidities of fresh coals to rank 53 Summary and conclusions 54 References 56 Appendix. Tabular data 57 ILLUSTRATIONS Figure Page 1. Carbonization apparatus 11 2. Titration assembly .13 3. Sample M, fresh coal carbonization series: titration curves and derived graphs 17 4. Sample M, fresh coal carbonization series 18 5. Sample M, naturally oxidized coal carbonization series: titration curves and de- rived graphs 19 6. Sample M, naturally oxidized coal carbonization series 20 7. Sample M, forced oxidized coal carbonization series: titration curves and derived graphs 22 8. Sample M, forced oxidized coal carbonization series 23 9. Sample M, infrared spectra of the fresh and oxidized coals and some chars and cokes from them 24 10. Sample N, fresh coal carbonization series: titration curves and derived graphs . 26 11. Sample N, fresh coal carbonization series 27 12. Sample N, naturally oxidized coal carbonization series: titration curves and derived graphs 29 13. Sample N, naturally oxidized coal carbonization series 30 14. Sample N, forced oxidized coal carbonization series: titration curves and derived graphs 31 15. Sample N, forced oxidized coal carbonization series 32 16. Sample N, infrared spectra of the fresh and oxidized coals and some chars and cokes from them 34 17. Sample O, fresh coal carbonization series: titration curves and derived graphs 36 18. Sample O, fresh coal carbonization series .37 19. Sample O, naturally oxidized coal carbonization series: titration curves and derived graphs 38 20. Sample O, naturally oxidized coal carbonization series 39 21. Sample O, forced oxidized coal carbonization series: titration curves and derived graphs 40 22. Sample O, forced oxidized coal carbonization series . . .42 23. Sample O, infrared spectra of the fresh and oxidized coals and some chars and cokes from them 43 24. Sample P, fresh coal carbonization series: titration curves and derived graphs 44 25. Sample P, fresh coal carbonization series 45 26. Sample P, naturally oxidized coal carbonization series: titration curves and derived graphs 46 27. Sample P, naturally oxidized coal carbonization series 47 28. Sample P, forced oxidized coal carbonization series: titration curves and derived graphs 48 29. Sample P, forced oxidized coal carbonization series 49 30. Sample P, infrared spectra of the fresh and oxidized coals and some chars and cokes from them 50 31. Variation of the acidities of the fresh coals with carbon and oxygen content ... 53 A. Total acidity vs. carbon content B. Total acidity vs. oxygen content C. Weaker component acidity vs. oxygen content TABLES Table Page 1. Sample M, fresh coal carbonization series — acidities 57 2. Sample M, variation of acidity during natural oxidation 58 3. Sample M, naturally oxidized coal carbonization series — acidities 58 4. Sample M, variation of acidity during forced oxidation 59 5. Sample M, forced oxidized coal carbonization series — acidities 59 6. Sample N, fresh coal carbonization series — acidities 60 7. Sample N, variation of acidity during natural oxidation 61 8. Sample N, naturally oxidized coal carbonization series — acidities 61 9. Sample N, variation of acidity during forced oxidation 62 10. Sample N, forced oxidized coal carbonization series — acidities 62 11. Sample O, fresh coal carbonization series — acidities 63 12. Sample O, variation of acidity during natural oxidation 64 13. Sample O, naturally oxidized coal carbonization series — acidities 64 14. Sample O, variation of acidity during forced oxidation 65 15. Sample O, forced oxidized coal carbonization series — acidities 65 16. Sample P, fresh coal carbonization series — acidities 66 17. Sample P, naturally oxidized coal carbonization series — acidities 67 18. Sample P, variation of acidity during forced oxidation 67 19. Sample P, forced oxidized coal carbonization series — acidities 68 20. Sample M, fresh coal — analytical data 69 21. Sample M, naturally oxidized coal — analytical data 70 22. Sample M, forced oxidized coal — analytical data 70 23. Sample N, fresh coal — analytical data 71 24. Sample N, naturally oxidized coal — analytical data 71 25. Sample N, forced oxidized coal — analytical data . 72 26. Sample O, fresh coal — analytical data 72 27. Sample O, naturally oxidized coal — analytical data 73 28. Sample O, forced oxidized coal — analytical data 73 29. Sample P, fresh coal — analytical data 74 30. Sample P, naturally oxidized coal — analytical data 74 31. Sample P, forced oxidized coal — analytical data 75 32. Sample Q, fresh coal — analytical data 75 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/acidicstructural212mahe ACIDIC STRUCTURAL GROUPS IN ILLINOIS COALS: Variation During Oxidation and Carbonization T. P. Maher, J. M. Harris, and G. R. Yohe ABSTRACT Changes of acidity taking place during carbonization of both fresh and oxidized coals were studied to secure new information on the processes of coal carbonization, coal oxidation, and on the effect of oxidation on coking properties. Three high-volatile Illinois coals and a low-volatile Eastern coal were ground to minus 40-mesh particle size, and separate portions of these were subjected to air oxida- tion for 64 days at 25°C ("natural" oxidation) and for 47 days at 110°C ("forced" oxidation). Laboratory-scale carbonization of the fresh and oxidized coals was performed at temperatures ranging from 200°C to 600°C. Variations in the contents of acidic structural groups during oxidation and carbonization of these coals were measured by means of potentiometric titration with sodium aminoethoxide in ethylenediamine, using antimony electrodes. Chemical analyses and infrared spectra were also obtained. All the coals studied behaved as dibasic acids in ethylenediamine. Natural oxidation caused an initial decrease in acidity, followed by a slow rise. Forced oxidation caused a substantial rise in acidity, especially in the more strongly acid groups. Formation of carboxyl groups was indicated in the high-volatile coals. In the carbonization of the high-volatile coals the original acidic groups began to decrease at temperatures above 200° C. The greatest decrease was from 400° to 500° C, but very weak groups were detected between 300° and 500° C, and their number and the temperature range over which they were found varied considerably in the fresh and oxidized coal carbonization products. The tendency of weak acidic groups to appear seemed to diminish as the rank of the coal increased. They were not found in the car- bonization of the low-volatile coal. INTRODUCTION Acidic structural groups in fresh bitumi- nous coals are generally considered to be largely phenolic hydroxyl groups, but in oxidized coals there are also carboxyl groups. Such functional groups have been studied by a number of investigators who used a variety of methods, some of which have been reviewed recently by D. W. van Krevelen and J. Schuyer (1957a). Other methods have been described by G. R. Yohe and Eva O. Blodgett (1947), J. K. Brown and W. F. Wyss (1955), and E. P. Uporova and S. R. Rafikov (1956). It should be noted that alcoholic hydroxyl groups, if present, would also be deter- mined by some of the methods used. The biggest problem in all the methods is the relative inaccessibility of the struc- tural groups. The determination of some of the groups requires a long reaction time (up to a week), and the very fine grinding leads to difficulties in the experiments (for example, in filtering). Another difficulty is the fact that the products of topochemical reaction (formed during the determination of functional groups or by the reagent used) may be ad- sorbed on the surface of the coal substance (E. P. Uporova and S. R. Rafikov, 1956). In the present investigation, acidic groups were determined by direct titration with sodium aminoethoxide in ethylenedia- mine. The method has a number of marked advantages. The swelling of bituminous coals in ethylenediamine improves the ac- cessibility of the groups, and a strongly basic medium enhances acidic strength so that very weak acids can be titrated. The method permits differentiation between groups of different acidic strength, and it is convenient and relatively fast. The analytical method was developed by M. L. Moss, J. H. Elliott, and R. T. Hall (1948) to determine acidic groups of pheno- lic strength and stronger in pure com- pounds and in "vinsol" resins. It has since been found applicable to the determination of hindered phenols (M. Katz and R. A. [9] 10 ILLINOIS STATE GEOLOGICAL SURVEY Glenn, 1952), phenolic esters (R. A. Glenn and J. T. Peake, 1955), an enolic compound (J. D. Brooks and T. P. Maher, 1957), per- acids, primary and secondary hydroper- oxides and hydrogen peroxide (A. J. Mar- tin, 1957), and certain tetrazole derivatives (T. P. Maher and G. R. Yohe, 1958). Recently W. E. Walker, J. P. Henry, and H. G. Davis (1958) reported that the tech- nique can be used to titrate certain poly- phenols, indole, carbazole, N-phenyl and a-phenyl amides and even 1,2- benzofluo- rene. Their observation that some quinones give acidic reaction products with ethylene- diamine agrees with findings in this labora- tory. In titrating a series of coals they found that a small quantity of added car- bazole helped to sharpen the final end point, particularly in lignites. They stated that exclusion of oxygen was necessary lor titration of the most weakly acid groups. The method was applied by J. D. Brooks and T. P. Maher (1954, 1957) to estimate acidic groups in a wide range of Australian coals. They also found that during the pyrolysis of a medium rank (83 percent carbon) vitrain, the main loss of acidity oc- curred between 400° and 500° C. When the same vitrain, freshly ground, was exposed to air at room temperature the oxygen first absorbed appeared to form mainly non- acidic groups. Subsequent exposure of the same sample to air at 105°C caused a steady increase in acidity, but again the initial rapid rise in oxygen content was due mainly to the formation of non-acidic groups. These results suggested that a systematic study of the changes of acidity in a number of fresh coals during carbonization and in the same coals after "natural" and "forced" oxidation might throw some light on the processes of coal carbonization, coal oxida- tion, and the effect of oxidation on coking properties. Acknowledgments The authors are indebted to Dr. O. W. Rees and the staff of the Section of Analy- tical Chemistry of the Illinois State Geologi- cal Survey for the chemical analyses, to P. E. MacMahon and J. M. Serratosa for the infrared spectra, to J. A. Harrison for the petrographic analyses, to J. A. Simon and others in the Coal Geology Section for help in the collection of samples, and to the managers of the collieries concerned for their cooperation. PROCEDURES The methods used for obtaining and treating the coals and preparing the samples for the titrations are as follows. Collection of Samples We collected coal Samples M, N, and O at the mines, and Sample P was sent to us by parcel post in answer to a request. Each sample consisted of several blocks of about 10 pounds weight or more of the freshest coal available at the mine concerned. Por- tions which appeared to have high mineral matter content were rejected. The blocks were placed in cans that were sealed after the air was flushed out with nitrogen. This was done immediately for Samples N and O, within a few hours for M, and on re- ceipt for P (six days after removal from the face). Sampling The most suitable block, free from dirt and fractures, was chosen and the outside edges either sawed off with a carborundum saw or chipped off with a hammer to yield a center core of about 5 pounds weight. This was put once through the jawcrusher and left overnight in a large nitrogen-filled desiccator, over calcium chloride, to remove any excess moisture. The following day the sample was put once through the roll mill, well mixed, and divided into three equal portions. The first portion was to be the "fresh coal sample." From it a representative sample of about 50 g was taken, sieved through a 40-mesh sieve, the oversize ground to pass, and the whole mixed and bottled under nitrogen for the Gieseler plasticity determination. CARBONIZATION 11 CARBONIZATION APPARATUS 19" Asbestos plug- Thermocouple Dry oxygen - free nitrogen ' Hoskms Electric Furnace Type FA 30059 110 volts 7-72 amps (max) 'Transtat" voltage regulator "Wheelco" temperature indicator and control \< 16- C Retort Side arm O.D Vycor tubing 0.0. 25mm. 1.0 22 mm. 9mm. ID. 7mm. Fig. 1. — Carbonization apparatus. The remainder of the first portion was reduced to minus 60-mesh by grinding in a nitrogen-filled ball mill and hand grind- ing of oversize to pass a 60-mesh sieve. The whole was then thoroughly mixed and placed in small bottles, each being filled completely. The bottles held a little more than 50 g so that two carbonization charges could be obtained from each and the small amount left could be discarded. In preparing the fresh coal sample the cans, jars, bottles, and ball mill that were to contain coal were flushed out with nitrogen before use, and after the sample was put in, if there was a space above it. Exposure to the air was always kept to a minimum. The second and third portions were pre- pared for the oxidation experiments by reduction to minus 40-mesh and thorough mixing. After either natural or forced oxidation, the sampling procedure was the same. The minus 40-mesh oxidized coal was thorough- ly mixed and then a representative sample of about 50 g taken from it for the Gieseler plasticity determination. The remainder was reduced to minus 60-mesh, mixed again, and put in small bottles. Oxidation Two methods of controlled aerial oxida- tion were used: 1) "Natural" Oxidation. — Minus 40-mesh coal was spread out in a thin layer on trays and exposed to the air in a room away from light and dust. The average temperature was about 25°C. The total time of exposure was 64 days. 2) "Forced" Oxidation. — Minus 40-mesh coal was spread out in a thin layer on two trays in a drying oven where it was exposed to air at a temperature of 110°C. The total time of exposure was 47 days. In both methods the coal was stirred periodically. Carbonization Separate portions of each coal were car- bonized to 200°, 300°, 350°, 400°, 450°, 500°, 550° and 600°C. A Gray-King-type tube furnace was used (fig. 1). A zone at least six inches long could be maintained so that the devia- tion from the carbonization temperature was never more than ±5°C at any point. 12 ILLINOIS STATE GEOLOGICAL SURVEY The coal was carbonized in Vycor retorts, the temperature being raised at the rate of 5°C per minute and then held at the selected final temperature for 45 minutes. Originally, a charge of 20 g of minus 60- mesh coal was used, but later charges were increased to 25 g in order to provide more sample for proximate and ultimate analy- ses. When a coke swelled outside the zone of uniform temperature, the part outside was discarded. If strong swelling was ex- pected, several carbonizations of 10 g charges were made. The charges and the chars or cokes formed were weighed to the nearest 0.01 g. Dry oxygen-free nitrogen was led into the retort to flush it out at the start and the flow was maintained at a very slow rate throughout the carbonization and cooling. The last traces of oxygen in the nitrogen were removed by a bubbler of alkaline anthraquinone /^-sodium sulfonate reduced by zinc amalgam. Concentrated sulfuric acid was used to dry the gas. Fine Grinding The stainless steel mill described by Yohe and Harman (1941), was used for the very fine grinding required for titration pro- cedure and infrared spectrum determina- tion. Stainless steel rods were used in it instead of balls. Its construction was such that the air could be flushed out with nitrogen after the sample had been added and the mill closed. About 15 g of minus 60-mesh coal was ground, or the entire product of a carbonization experiment. Coals and unconsolidated chars were ground overnight; cokes over two nights or even three if they were particularly hard. Cokes were hand ground quickly to a size that the mill could handle. A check by J. A. Harrison on a high-volatile coal showed that overnight grinding from minus 60-mesh reduced 90 percent of it to five microns or less. The samples after grinding were placed in small bottles, previously flushed out with nitrogen. The nitrogen flushing was also used subsequently, any time that the bot- tles were opened, to insure removal ol oxygen from the gas above the sample. Titrations The apparatus and procedures used in the titrations were essentially those de- scribed by Brooks and Maher (1957) except for the following modifications: (1) A Leeds and Northrup student-type potentiometer was used, in conjunction with a Weston Standard cell and a light- scale galvanometer, to measure the E.M.F. This had a range of to 1600 millivolts and a limit reading of one millivolt. (2) The rate of addition of the titrant was changed to 0.2 ml per 3-minute inter- val because the former rate of 0.2 ml per 2-minute interval was found to be a little too fast for some samples in which large changes of E.M.F. occurred. (3) A longer time was allowed for equi- librium to be established before beginning the titration. Reagents Monoethanolamine (Carbide and Car- bon Chemical Company) was allowed to stand over sodium hydroxide pellets and was purified by triple distillation through a fractionating column packed with 14-inch porcelain Berl saddles. Ethylenediamine (Eastman Kodak Com- pany 95-100 percent and Dow Chemical Company 98 percent) was allowed to stand over sodium hydroxide pellets, further puri- fied by refluxing with sodium until the latter was no longer consumed, and then distilled over sodium through a fractionat- ing column packed with Berl saddles using an Ascarite guard tube to exclude carbon dioxide. Azeotropic distillation with ben- zene was found to be less satisfactory. Sodium, A. R. (Rascher and Betzold, Inc.) was used as purchased after trimming to remove corroded surfaces. Antimony metal (Powder) (Baker Chem- ical Company) was purified by melting it in a crucible, skimming the surface, and pour- ing off the metal into another crucible. The process was repeated several times. Sisco 300 Grease (Swedish Iron and Steel Corporation) was used to lubricate all joints TITRATIONS 13 n^ Titrant reservoir 250 ml. TITRATION ASSEMBLY 10 ml. Burette Capillary leak tube Fig. 2. — Titration assembly. "Fraction" no- tations designate standard taper joint size. and stopcocks because of its resistance to ethylenediamine. Pure benzoic acid (National Bureau of Standards) was used as obtained. Sodium aminoethoxide titrant (ap- proximately 0.2 N) was prepared in the fol- lowing manner: Sodium (2.5 grams) was washed successively with small volumes of ethanol and monoethanolamine and dis- solved in 100 milliliters of monoethanola- mine. The flask was cooled in ice when necessary to slow down the rate of reaction. When all the sodium had dissolved, the solution was made up to 500 ml with anhydrous ethylenediamine. It was stand- ardized against pure benzoic acid. Apparatus A diagram of the titration apparatus is shown in figure 2. The reference electrode was in the titrant stream below the stopcock of the burette. It consisted of a small bead of antimony poured while molten into the cup at the end of the electrode tube and ground off carefully when cool so that the antimony surface was even with the end of the tube. It was connected by a piece of platinum wire, through a glass seal, to the copper lead to the potentiometer. The platinum- copper connection was made with silver solder. The indicator electrode dipped into the titration flask. It consisted of an antimony rod fitted into a stainless steel rod, the end of which was drilled out to accommodate it. The antimony rod was made by sucking up molten antimony (only a little above the melting point) into a glass tube of appropri- ate internal diameter by means of a rubber bulb. When the antimony solidified, the glass tube was cracked by holding it in cold water, then it was chipped away from the metal. The electrical connection between the two electrodes was effected by a narrow glass tube from just above the burette tip dipping below the surface of the liquid in the flask. The bottom end was closed by a fritted glass disc made from an ultrafine microfilter funnel. This was necessary to prevent diffusion of the solution being titrated up to the reference electrode dur- ing the slow titrations. The burette was of 10 ml capacity grad- uated to 0.05 ml. The limit of reading was 0.01 ml. Detailed Titration Procedure The glass-covered stirring bar was placed in the titration flask, the capillary leak tube inserted and the electrode neck plugged with cotton. Approximately 0.2 g of sample was weighed out accurately and transferred quantitatively through a powder funnel to the flask, the last traces being washed in with 40 ml of anhydrous ethylenediamine. The flask was then stoppered. 14 ILLINOIS STATE GEOLOGICAL SURVEY The titrant was adjusted to a suitable level in the burette, the protective tube removed from the tip assembly which was then cleaned with several swabs of cotton to remove titrant from the outside, and the flask then put in position. The end and sides of the antimony rod were polished with a piece of fine grade emery cloth and the adhering antimony powder carefully removed by successive polishings with cotton. The antimony rod was fitted into the stainless steel holder which had previously been fitted through the rubber stopper. The plug was then removed from the appropriate neck of the flask and the indi- cator electrode inserted so that about half an inch of the antimony rod was below the surface of the liquid. The magnetic stirrer was turned on and the indicator electrodes connected to the potentiometer. Pre-titration Period The original E.M.F. was measured and the time noted. The value of the E.M.F. depended on the sample being titrated and other factors, but often it was of the order of 550 millivolts. It began to rise steadily. It was measured periodically and the titra- tion was not begun until the system was at equilibrium. This usually required about three hours, and in many cases there was a rise of about 400 mv. Titration Period Before starting the titration, the potentio- meter was restandardized against the stand- ard cell. The E.M.F. was measured, the time and the burette reading noted. Then approximately 0.2 ml of titrant was added to bring the meniscus to one of the 0.05 ml graduations. The apparatus was lifted slightly, and the flask tapped lightly back on the magnetic stirrer to dislodge any drop hanging on the burette tip. A sheaf of about a dozen filter papers on the top of the magnetic stirrer acted as a cushion and also helped to insulate the flask from any heat developed in the stirrer. After 2i/2 minutes, the measurement of the new E.M.F. was begun so that it could be concluded by 3 minutes when another 0.20 ml could be added. The new E.M.F. was noted, the E.M.F. change recorded, and the E.M.F. change per unit volume of titrant added was calculated. This procedure was continued until the titration was judged to have been com- pleted. The stirrer was turned off, the titration flask disconnected and replaced by the pro- tective tube containing titrant after the tip had been cleaned as before. The burette was refilled from the reservoir. This helped keep the inside surface clean. The titration residues were poured into a bottle for later recovery and repurification of the ethylene- diamine. Titration Curve The titration curve was obtained by plot- ting the E.M.F. against the volume of ti- trant added. Inflection points indicated end points in the titration. The derived graph of change of E.M.F. per unit volume of titrant (AE/AV in the figures) against volume of titrant added, showed the end points as peaks and helped, in conjunction with the titration curve itself, to determine their positions accu- rately. From the volume of titrant correspond- ing to an end point, the acidity could be calculated in milliequivalents per gram of sample. Determination of Carbon Dioxide in the Ethylenediamine A blank titration on 40 ml of ethylene- diamine was performed weekly to deter- mine the volume of titrant equivalent to its content of carbon dioxide. In this case, the titrant was added in 0.05 ml incre- ments. In the time ordinarily required to use a liter of ethylenediamine the blank usually rose from about 0.05 ml to 0.10 ml. Precautions which helped to keep it low were keeping the neck and stopper of the bottle clean and protected with polyethyl- ene sheeting over cotton, and always with- drawing the solvent by means of a pipette fitted with a rubber bulb. NO. 6 COAL FROM KNOX COUNTY 15 Standardization of Titrant The titrant was standardized by titrating about 0.1 g of pure benzoic acid, accurately weighed, in 40 ml of ethylenediamine. In the region of the end point, the titrant was added in 0.05 ml increments. The inflection was very sharp. The value of the blank was subtracted before the normality of the sodium aminoethoxide was calculated. The titrant was standardized periodically. Infrared Studies The infrared spectra were determined with a Perkin-Elmer Model 21 double beam spectrophotometer. At first the potassium bromide pellet technique was used for mounting the sample, but it was not found possible to remove completely or to compen- sate for the water absorbed from the atmosphere while grinding the sample with the potassium bromide. Thus it was un- certain how much of the hydroxyl absorp- tion in the spectrum (at 3600 cm 1 to 3100 cm 1 ) was due to water and how much was actually due to hydroxyl groups in the sample. A method, based on a suggestion from P. Macdonald (1957), was developed by J. M. Serratosa for obtaining the spectrum in this region by a mixed fluorolube-hexa- chlorobutadiene mull technique. Fluoro- lube alone was found too viscous for ef- ficient grinding but hexachlorobutadiene alone tended to evaporate during grinding and was also difficult to use in the cell because of its low viscosity. When the mixed mulling agent was used grinding was efficient, and by the end of the grinding time most of the hexachlorobutadiene had evaporated anu the mull had a viscosity which made it suitable for mounting on the sodium chloride window of the cell. The samples were dried at 110°C in a vacuum pistol over phosphorous pentoxide for about six hours before mulling. The only disadvantage of this technique ap- peared to be that it was harder to obtain the same sensitivity (judged by the C-H absorption around 3000 cm 1 ) as in the po- tassium bromide method. Long grinding times were required. The assignment of the absorption bands is based in general on work cited by D. W. van Krevelen and J. Schuyer (1957b), R. A. Friedel and J. A. Queiser (1956) and G. Bergmann, G. Huck, J. Karweil, and H. Luther (1957). RESULTS AND DISCUSSION "Total Acidity" and "Component Acidities" Most titration curves had more than one inflection, indicating that groups of differ- ent acidic strength were present. The stronger groups titrated first. The acidity in milliequivalents per gram corresponding to the final inflection has been termed the "total acidity." The amounts of the stronger and weaker groups which add up to give the total acidity have been termed "component acidities" and are always listed in order of decreasing acidic strength (order of titration) across the tables. In the diagrams and figures the or- der of decreasing acidic strength is ar- ranged from top to bottom. The reproducibility of component acidi- ties was reasonably good in most tests. An attempt has been made to follow the varia- tion of these component acidities, as well as the total acidity, through each carboniza- tion series. In the tables the component acidity is placed directly below the one at the previous temperature with which it corresponds. In some cases this is easy to see, but in other cases some uncertainty is involved. When a value is put under and between two component acidities of the preceding test, it indicates that differentia- tion between them is no longer possible. Acidic Oxygen Except where otherwise stated, acidic ox- ygen has been calculated on the basis of one oxygen atom per equivalent of acidity. SAMPLE M, NO. 6 COAL FROM KNOX COUNTY, ILLINOIS Sample M was a selected clean specimen of high-volatile C bituminous coal taken from a strip mine operating in the Illinois 16 ILLINOIS STATE GEOLOGICAL SURVEY No. 6 Coal in Knox County, Illinois. There was about 50 feet of overburden at the site where the sample was taken. Fresh Coal The chemical and petrographic analyses, swelling and plastic properties of the fresh coal, and the description and chemical analyses of the chars and cokes obtained from it by carbonization, are given in table 20. It may be noted that the carbon content of the fresh coal was low (79.60 percent) and the percentage of vitrinite high (95.5 percent). The sulfur content was fairly high (3.21 percent), most (2.17 percent) being in organic form. Carbonization Although the swelling properties ap- peared only moderate (free swelling index 3 1/ 2 ), the sample swelled out of the cup during the determination of Gieseler plas- ticity. The final carbonization product at 600 °C was a slightly shrunken hard coke, but the cokes obtained at 400°C and 450°C were highly swollen and frothy. Apparently a slow rate of heating, or holding at tem- peratures in the plastic range, allowed swelling which was prevented at a faster rate of heating. The Gieseler maximum fluidity was fairly high (2320 dial divisions per minute), but unreliable because the sample swelled out of the cup. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the fresh coal carboniza- tion series is shown in figure 3. The total acidity and component acidi- ties at each carbonization temperature are given in table 1, which also gives the total oxygen, acidic oxygen, and the acidic ox- ygen as percentage of total oxygen. The fresh coal titration curve had two distinct inflections of large break. The first was due to groups which could not be dif- ferentiated from benzoic acid in ethylene- diamine in a mixed titration of the coal and the acid. The second was due to groups which were weaker than benzoic acid but stronger than 3,5-dimethylphenol in ethyl- enediamine. Up to 350° C the form of the titration curve remained the same, although both component acidities had decreased some- what. At 400 °C the stronger component acidity was the same as at 350° C, the weaker had further decreased, and a third inflection had appeared in the titration curve, due to groups of still lower acidic strength. The form of the titration curve was much different at 450 °C. The starting E.M.F. was much lower than previously, although a longer time was allowed for equilibration. Three inflections could be distinguished, the first and third being much more definite than the second (which could not be detected on one of the titra- tions). The first appeared to correspond to what was left of the two strongest com- ponent acidities at 400° C. The second ap- parently corresponded to the new weaker acidity first seen at 400 °C, which had in- creased slightly. The third inflection ap- peared to be due to very weak groups not formerly present. The small peak at 3.9 ml in the derived graph was thought to be due to an irregularity. These three inflections could still be dis- tinguished at 500°C, but the relative num- ber of groups responsible for each had changed. Less than half of the first re- mained, the second had nearly twice as many, and the third remained constant. At 550°C and 600°C only one inflection was observed. The total break in the curve was much less than for the lower tempera- ture products. These changes can be se^n more clearly by reference to the actual titration curves in figure 3 and are shown diagrammatically in figure 4a. In the latter the acidities are given in milliequivalents obtained by mul- tiplying the total and component acidities by the dry ash-free weight of char or coke in each case. This is intended to eliminate changes in acidity per gram that arise only from weight loss during the carbonization. Stronger component acidities are placed above weaker in the histogram. NO. 6 COAL FROM KNOX COUNTY 17 900 800 . \ FRESH COAL \ 350° CHAR \ 400° COKE 700 \ 600 V-^-v 500 - / \ 400 ■ 1 ^^— 300 \^ 200 - V) b g 100 _) _) 2 . . . i . i i i 0.217 N 0.217 N _ i .. i , i , 0.217 N 500 300 200 100 900 800 700 600 600- 300 200 12 3 4 5 12 3 4 VOLUME OF TITRANT (ML.) Fig. 3. — Sample M, fresh coal carbonization series: Titration curves and derived graphs. Figure 4b shows the variation in weight of total oxygen and acidic oxygen through- out the carbonization series. It shows that, although the weight of total oxygen fell at a fast, fairly steady rate between 300° and 500 °C and then slowed somewhat, the total acidic oxygen fell in two steps. The first was between 250° and 400 °C, being fastest a little above 300°C, and the second was between 450° and 550°C, most being lost between 500° and 550° C. The acidic oxy- gen apparently was converted largely into a non-acidic form, as the weight of non- acidic oxygen increased markedly. The percentage of oxygen in acidic form was at its maximum at 450° to 500° C where it accounted for almost 80 percent. 18 ILLINOIS STATE GEOLOGICAL SURVEY Naturally Oxidized Coal Variation of Acidic Groups During Oxidation Several determinations of acidic group content were made during the oxidation. The samples were obtained by taking a large number of small increments from dif- ferent places onthe exposed coal and grind- ing by hand. The results are shown in table 2. The first determination, made after 18 days, showed that both component acidities had decreased to give a loss of 0.34 milliequiva- lents per gram in the total acidity. The changes in the rest of the period (up to 64 days) did not appear to be significant. Carbonization The analytical data for the carbonization series of the naturally oxidized Sample M are given in table 21. The only significant difference in the chemical analysis of the oxidized coal from that of the fresh coal was a small decrease in the carbon which slightly increased the oxygen (obtained by difference). It was noted that during carbonization the oxidized coal lost less of its oxygen but more of its hydrogen at lower temperatures than did the fresh coal. The oxidized coal had slightly lower volatile matter and calo- rific value but the maximum Gieseler fluidity dropped remarkably (from 2320 to 9 dial divisions per minute) and the plastic range was shorter. The free swelling index however increased (from 3i/ 2 to 4). Carbonization yielded a soft unswollen coke at 400° C, and increase in temperature increased the hardness and caused a slight shrinkage. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the naturally oxidized coal carbonization series is shown in figure 5. The total acidity and component acidi- ties at each carbonization temperature are given in table 3, which also gives the total oxygen, acidic oxygen, and the acidic oxy- gen as percentage of total oxygen. 100 200 300 400 500 CARBONIZATION TEMPERATURE -°C 600 Fig. 4. — Sample M, fresh coal carbonization series: A. Milliequivalents of total and component acid- ities in each char or coke. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization temperature. Shaded areas represent distinguishable compo- nent acidities in order of decreasing acidic strength, the strongest at the top. NO. 6 COAL FROM KNOX COUNTY 19 500 400 1 2 3 4 2 3 4 i 2 3 4 5 900 - 800 - 450° COKE 500° COKE 600° COKE 700 "N 1 - 600 . L : 500 11 400 • 300 I ■ V 0.171 N 0.171 N l v^ 0.233N 100 100 12 3 4 VOLUME OF TITRANT (ML) Fig. 5. — Sample M, naturally oxidized coal carbonization series: Titration curves and derived graphs. The coal itself gave a smooth curve with two sharp inflections. It was similar to that for the fresh coal except that the second inflection occurred at a higher E.M.F. Up to 350 °C the form of the curve was unchanged, but at that temperature each component acidity had decreased slightly. There was also a shoulder on the second peak of the derived graph, seeming to indi- cate that a small number of still weaker groups were present that could not be dif- ferentiated with certainty. At 400 °C this supposition was confirmed by the clear differentiation of a weaker component acidity giving rise to a third inflection in the curve. 20 ILLINOIS STATE GEOLOGICAL SURVEY 100 200 300 400 500 CARBONIZATION TEMPERATURE-°C 600 Fig. 6. — Sample M, naturally oxidized coal carboni- zation series: A. Milliequivalents of total and component acid- ities in each char or coke. B. Variation of weight of oxygen (acidic and non- acidic) with carbonization temperature. At 450 °C, as in the case of the fresh coal, differentiation between the two stronger component acidities was no longer ob- tained. The other component acidity from 400° C still remained but had decreased in value. The curve in the latter stages was irregular, but showed no further reprodu- cible inflections. Only one inflection was observed at 500°, 550° and 600°C, the acidity gradually decreasing in amount. Figure 6a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char or coke. The variation in the weight of total oxy- gen and acidic oxygen throughout the carbonization series is shown in figure 6b. It shows that the total oxygen content de- creased rapidly between 300° and 450°C and slightly less rapidly between 450° and 600° C. The acidic oxygen disappeared slowly between 200° and 400 °C and very rapidly between 400° and 500 °C. Little if any of this acidic oxygen appeared to be converted to non-acidic oxygen. The percentage of oxygen in acidic form in the solid carbonization products was never above 50 percent, reaching its maxi- mum of about 47 percent at 400°C. This was only slightly higher than in the coal itself. Forced Oxidized Coal Variation of Acidic Groups During Oxidation Table 4 shows that there was a gradual increase in the total acidity (from 3.36 to 4.15 milliequivalents per gram) over the 47- day period. The small size of the increase (0.14 milliequivalents per gram) in the first 9 days may have been due to an initial de- crease corresponding to natural oxidation. The stronger component acidity showed a marked increase until finally it could be differentiated into two separate component acidities of slightly different acidic strength. The weaker component acidity decreased in the first period, then increased by a small amount before decreasing again. Shaded areas represent distinguishable compo- nent acidities in order of decreasing acidic strength, the strongest at the top. NO. 6 COAL FROM KNOX COUNTY 21 Carbonization The analytical data for the carbonization series of forced oxidized Sample M are given in table 22. The oxygen content of the oxidized coal was about twice that of the fresh coal. Throughout the carbonization series the oxygen content was always significantly greater than that of the fresh coal product at the same temperature. The oxidized coal showed marked de- creases in volatile matter (from 49.4 to 39.1 percent) and calorific value (from 14,380 to 11,930 Btu per pound or 7989 to 6628 calories per gram). It was non-swelling and the Gieseler plasticity was unobtainable. Carbonization yielded no cokes, but gave slightly coherent chars at the higher tem- peratures. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the forced oxidized coal carbonization series is shown in figure 7. Of interest is the small but reproducible inflection in the early part of the curve before the first large inflection. It was ob- tained in the titration of the coal and the 200° and 300° chars. Because of its order of magnitude it is thought to correspond to the stronger component acidity of the fresh coal. The other acidity before the first large inflection would then be due to groups of slightly lower acidic strength formed in the forced oxidation. These are postulated to be carboxyl groups. The pres- ence of such groups is indicated by absorp- tion in the infrared spectrum at 1675-1700 cm 1 (carbonyl) for the oxidized coal and for the chars up to 400 °C and by the de- velopment of pronounced alkali solubility, and it is consistent with the findings of other workers on such oxidized coals. Differentiation between the two strong component acidities was not achieved at 350° or 400°C although the first inflection now represented an acidity only a little less than the sum of the two formerly present and there was still absorption at 1675-1700 cm 1 in the infrared. The total acidity and component acidi- ties at each carbonization temperature are given in table 5, which also gives the total and acidic oxygen. The acidic oxygen was calculated on the assumption of one atom of oxygen per equivalent of acidity, except for the second strongest component acidity, which was assumed to be due to carboxyl groups as stated above. For this part the acidic oxygen was calculated on the basis of two oxygen atoms per equivalent of acidity. For the 350° and 400 °C chars, where differentiation could no longer be seen between the two strong component acidities, approximate values for the acidic oxygen were calculated assuming that the ratio between the groups responsible stayed the same as at 300° C. The small inflection at about 5.4 ml in the titration curve of the oxidized coal did not appear to be reproducible and was therefore taken to be an irregularity. The 200° C char gave a titration curve of the same form as the coal but with a slightly lower total acidity. At 300 °C a new inflection due to very weak groups appeared. It was not very sharp, but was reproducible. It persisted up to 450 °C, and the acidity corresponding to it increased to 400 °C and then decreased. The initial E.M.F. at 450 °C was more than 200 millivolts lower than at 400° C. At 500°, 550°, and 600°C only one inflec- tion of relatively small break was obtained. The percentage of oxygen in acidic form reached a maximum at 400 °C where it amounted to approximately 75 percent. Figure 8a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char. At 350° and 400 °C the strongest component acidity is further divided by a broken line showing the postulated ratio of the two types of groups when they are no longer differenti- ated in titration. The variation in the weight of total ox- ygen and acidic oxygen (based on the as- sumptions stated earlier) through the car- bonization series is shown in figure &b. The region where the amount of carboxyl is uncertain is shown by broken lines. 22 ILLINOIS STATE GEOLOGICAL SURVEY 200 115 300 Fig. 7.— Sample M, forced oxidized coal carbonization series: Titration curves and derived graphs. NO. 6 COAL FROM KNOX COUNTY 23 100 200 300 400 500 CARBONIZATION TEMPERATURE- °C 600 Fig. 8. — Sample M, forced oxidized coal carboniza- tion series: Between 350° and 400 °C acidic oxygen increased at the expense of non-acidic ox- ygen but between 400° and 500 °C the reverse was the case. Infrared Spectra The infrared spectra of fresh, naturally oxidized, and forced oxidized Sample M and of some of the chars and cokes obtained from them are shown in figure 9. All spec- tra are uncorrected. Fresh Coal Series The OH (and N-H?) absorption band with a very flat "peak" at 3350 cm- 1 was spread over a large frequency range indi- cating extensive hydrogen bonding, judg- ing by the fluorolube spectra, it was fairly strong up to 350 °C after which it decreased markedly. However, it still appeared to be present up to 500° C. There was no indication of aromatic C-H absorption just above 3000 cm- 1 . Aliphatic and/or naphthenic (saturated cyclic) C-H stretching absorption of me- dium strength was found at 2930 cm 1 with a shoulder at 2870 cm 1 . It decreased slowly to 350 °C, rapidly to 400 °C, and appeared to be gone at 450° C. No C : O absorption was found in the 1700 cm 1 region. The characteristic coal absorption band, strong and broad, appeared at 1600 cm 1 . It is usually attributed to aromatic struc- tures, perhaps reinforced by conjugated carbonyl groups. It remained throughout the series and although it did decrease, this may have been due to the difficulty of get- ting a good spectrum with the higher tem- perature cokes because of the increased scatter. A band of medium strength with a peak at about 1440 cm 1 indicated the presence of aliphatic and/or naphthenic CH 2 and A. Milliequivalents of total and component acid- ities in each char. B. Variation of weight of oxygen (acidic and non- acidic) with carbonization temperature. Shaded areas represent distinguishable compo- nent acidities in order of decreasing acidic strength, the strongest at the top. 24 ILLINOIS STATE GEOLOGICAL SURVEY 3000 2500 2000 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 FREQUENCY- CM"' Fig. 9. — Sample M, infrared spectra of the fresh and oxidized coals and some chars and cokes from them. NO. 6 COAL FROM JEFFERSON COUNTY 25 CH 3 groups. The band began to decrease appreciably after 300 °C and appeared to be practically gone at 450° C. CH 3 groups or cyclic CH 2 groups were also indicated by weak absorption at about 1370 cm 1 which became weaker still as the temperature increased, finally disappearing between 400° and 450° C. No definite assignment could be made for any other absorption bands. Naturally Oxidized Coal Series The spectrum of the naturally oxidized coal was not very different from that of the fresh coal. There was no C:0 absorption at about 1700 cm 1 , indicating that no significant number of carboxyl groups was formed in the oxidation. Hydroxyl absorption appeared less strong and the flat peak was at a slightly higher frequency (3440 cm 1 ). It began to de- crease noticeably above 350 °C and seemed to have disappeared at 500 °C. The behavior of the other bands throughout the series was substantially the same as for the fresh coal. Forced Oxidized Coal Series The most noticeable feature of the spec- trum of the forced oxidized coal was the broad shoulder at about 1700 cm 1 on the side of the large 1600 cm 1 band. It indi- cated C:0 absorption presumably from carboxyl groups formed in the oxidation. At 300° and 350 °C in the series it showed as a peak rather than a shoulder, had al- most disappeared at 400 °C, and could not be seen at 450° C. It is noteworthy that the absorption due to C-H at 2910 cm 1 and CH 2 and CH 3 at 1430 cm 1 was much less than in the fresh and naturally oxidized coals. The very weak peak at 1370 cm 1 due to the CH 3 or cyclic CH 2 groups was hardly perceptible. This seems to indicate that at least some of the carboxyl groups were formed by the oxidation of these aliphatic or naphthenic groups (cf. B. K. Mazumdar, K. S. Anand, S. N. Roy and A. Lahiri, 1957). The gradual disappearance of the various other absorption bands with increase of carbonization temperature followed much the same pattern as for the fresh coal. SAMPLE N, NO. 6 COAL FROM JEFFERSON COUNTY, ILLINOIS Sample N was a selected clean specimen of high-volatile B bituminous coal taken from an underground mine operating at a depth of about 750 feet in the No. 6 seam in Jefferson County, Illinois. Fresh Coal The analytical data for the carbonization series of fresh Sample N are given in table 23. Although the carbon content (81.59 per- cent) was two percent higher than for Sample M, the oxygen was also slightly higher. The ash (9.7 percent) and sulfur (0.96 percent) were moderate. More than half the sulfur was organic. The percentage of vitrinite was fairly high (91.6 percent). Carbonization The free swelling index (4) was slightly higher than for Sample M, but the Gieseler maximum fluidity was much lower (27 dial divisions per minute) and the plastic range shorter. Upon carbonization, slightly shrunken cokes were obtained at 450 °C and higher. As the temperature was raised, the cokes increased in hardness from moderately hard to hard. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the fresh coal carboniza- tion series of Sample N is shown in figure 10. The total acidity and component acidi- ties at each carbonization temperature are given in table 6, which also gives the total oxygen and acidic oxygen. The coal itself gave a smooth curve with two sharp inflections. There was a small rise in E.M.F. after the first inflection, be- fore the fall began for the second. The total acidity was significantly higher than for 26 ILLINOIS STATE GEOLOGICAL SURVEY 2 3 4 VOLUME OF TITRANT (ML.) 600 400 12 3 4 12 3 4 5 12 3 4 900 ~/\ 800 \ 450° COKE 500° COKE \ 550° COKE - 700 \ iV - 600 \ ^^\ - 500 - a\ 1 ^-_ - 400 - / v\ \ - 300 Ww-^ - 0.226 N 0.222 N 0.226 N Fig. 10. — Sample N, fresh coal carbonization series: Titration curves and derived graphs. Sample M which perhaps indicated that acidity correlates with oxygen content rather than carbon content. The stronger component acidity accounted for less of the total than for Sample M. The form of the curve was the same at 200 °C, the weaker component acidity hav- ing decreased slightly. At 300 °C a third inflection occurred late in the titration curve. It was not sharp but was reproducible. Apparently it was due to extremely weak acidic groups. The titration curve at 350° C was of the same form as that at 300 °C and had three inflections, the third being very faint. All NO. 6 COAL FROM JEFFERSON COUNTY 27 100 200 300 400 500 600 CARBONIZATION TEMPERATURE - °C component acidities had decreased from their values at 300 °C. At 400 °C a fourth inflection appeared, caused by groups stronger than those caus- ing the third inflection, but weaker than those causing the second inflection at 300°C and 350°C. The three component acidities found at these temperatures were still present although their values had de- creased still further and the final faint in- flection was barely detectable. The small peak at 1.3 ml in the derived graph was due to an interruption in the titration and is not significant. Three inflections were obtained in the titration curve at 450° C. In the curve shown the starting E.M.F. was over 900 millivolts, the first inflection was very prominent and the other two were very faint. In the other two titrations performed the starting E.M.F. was less than 800 milli- volts, the first inflection was not so sharp, and the third inflection was the most prom- inent. The reason for this variation in be- havior is not known, but the reproduci- bility of the positions of the inflections was reasonably good. The stronger two com- ponent acidities appeared to come from the two strongest at 400 °C. The weakest com- ponent acidity appeared to come from the third strongest at 400° C. At 500 °C only two inflections were ob- tained. The component acidities appeared to correspond to the strongest and to the sum of the weakest two at 450 °C. At 550 °C and 600 °C only one inflection was found after which the curve was rather irregular. Figure 11a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char or coke. The variation in the weight of total oxy- gen and acidic oxygen throughout the Fig. 11. — Sample N, fresh coal carbonization series: A. Milliequivalents of total and component acidities in each char or coke. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization tempera- ture. Shaded areas represent distinguishable com- ponent acidities in order of decreasing acidic strength, the strongest at the top. 28 ILLINOIS STATE GEOLOGICAL SURVEY carbonization series is shown in figure lib. The apparent increase in the weight of total oxygen up to 300 °G is most probably caused by error due to the use of oxygen values obtained by difference. From 300 °C to 550 °C the total oxygen dropped rapidly and at a fairly constant rate. This rate de- creased markedly between 550 °G and 600°C. The weight of acidic oxygen decreased slightly to 200 °C and then increased to about one and a half times this value due to the appearance of the very weakly acidic groups at the expense of non-acidic oxygen. From 300 °G to 400 °C the acidic oxygen de- creased at about the same rate as the total oxygen. The rate was faster to 450 °C and then slower to 500°C. In the 500° to 550 °C interval the acidic oxygen fell off to a very low value which was only slightly less at 600 °C. Non-acidic oxygen increased at the expense of acidic in this range. The percentage of oxygen in acidic form was greatest at 300° C (over 77 percent) due to the very weakly acidic groups present at that temperature. Naturally Oxidized Coal Variation of Acidic Groups During Oxidation As shown in table 7 there was a fall in total acidity (0.56 milliequivalents per gram) early in the oxidation of Sample N, followed by a rise back almost to the origi- nal value. This occurred with both component acidities also, except that the stronger in- creased faster than the weaker, and at the end of 44 days was significantly greater than its original value. In the last 20 days it decreased slightly. Carbonization The analytical data for naturally oxi- dized Sample N are given in table 24. The oxidized coal had a slightly higher oxygen content than the fresh coal but the chars and cokes from it had lower oxy- gen than the products at the same tempera- tures from the fresh coal. The oxidized coal had a slightly lower volatile matter content and calorific value than the fresh coal, the free swelling in- dex was unchanged, but the already low Gieseler plasticity had decreased to a barely measurable amount. The chars and cokes obtained on car- bonization were very similar to those from the fresh coal, perhaps being not quite as hard. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the naturally oxidized coal carbonization series for Sample N is shown in figure 12. The total acidity and component acidi- ties at each carbonization temperature are given in table 8 which also gives the total oxygen and acidic oxygen. The oxidized coal gave a smooth titra- tion curve with two sharp inflections which however were not as steep as for the fresh coal. The total acidity had decreased slightly although the stronger component acidity had increased by a small amount. Up to 300° C the form of the curve re- mained the same. There was a small de- crease in the weaker component acidity. This component acidity had further de- creased at 350 °C and a third inflection due to weaker groups made its appearance. At 400° this new component acidity had increased but of the original two the stronger had decreased slightly and the weaker had only about half its original value. The initial E.M.F. at 450°C was still above 900 millivolts, but the total break was only about 400 millivolts. There were two inflections, then some irregularities. The first inflection was taken as corre- sponding to the remnants of the stronger two component acidities at 400 °C. At 500 °G and higher temperatures only one inflection was found in the titration curve. Figure 13a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char or coke. The variation in the weight of total oxy- gen and acidic oxygen throughout the carbonization series is shown in figure 136. NO. 6 COAL FROM JEFFERSON COUNTY 29 900 800 400 2 3 4 VOLUME OF TITRANT(ML) Fig. 12. — Sample N, naturally oxidized coal carbonization series: Titration curves and derived graphs. The total oxygen decreased from 300 °C at a fast rate which was greatest and fairly constant from 350° C to 450 °C. The weight of acidic oxygen decreased slightly to 300 °C and then rose by a small amount to 350 °C due to the appearance of the new weaker acidity at that tempera- ture. It decreased rapidly between 350 °C and 450 °C and faster still between 450 °C and 500 °C with the disappearance of the weakest component acidity. A small amount of this acidic oxygen was apparently con- 30 ILLINOIS STATE GEOLOGICAL SURVEY 100 .200 300 400 500 CARBONIZATION TEMPERATURE- °C 600 verted to a non-acidic form in this range. The percentage of oxygen in acidic form was highest in the solid carbonization prod- uct at 400°C. Forced Oxidized Coal Variation of Acidic Groups During Oxidation At first difficulty was experienced in the titration of the forced oxidized coal. The sample became sticky in ethylenediamine and adhered to the bottom of the flask. It was found that 10 ml of benzene added before the ethylenediamine gave a homo- geneous suspension which titrated satisfac- torily. The blank also was determined with added benzene in this case. Table 9 shows that the total acidity in- creased from 3.78 to 5.37 milliequivalents per gram over the 47 days. The stronger component acidity in- creased to more than twice its original value of 0.65 milliequivalents per gram in 17 days, showed a slight further increase after 35 days, and finally after 47 days had risen to more than three times its original value. No new inflection was detected in the titration curve (compare with forced oxidized coal Sample M). The weaker component acidity showed a small decrease after 17 days, a larger in- crease in the next 17 days, and again a decrease in the final 12 days to give a net increase of 0.16 milliequivalents per gram over the complete period. Although this behavior appeared ir- regular it was noted that the weaker com- ponent acidity of Sample M varied in a somewhat similar manner during forced oxidation. Carbonization The analytical data for the carbonization series are given in table 25. Fig. 13. — Sample N, naturally oxidized coal car- bonization series: A. Milliequivalents of total and component acid- ities in each char or coke. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization temperature. Shaded areas represent distinguishable compo- nent acidities in order of decreasing acidic strength, the strongest at the top. NO. 6 COAL FROM JEFFERSON COUNTY 31 700 _200 •""X 1 2 3 4 5 6 12 3 4 12 3 900 \ A 800 V 350° CHAR V 400° CHAR \ 450° CHAR 700 >y \ - 600 \ \ . \ - 500 A\ A ^— — - r\ ^~-~^ - 400 • A rk~ / \J\ V - 300 ■ A. A i \ \ - / 1 0.203 N -/ i iii OZ06N 0.203 N 500 400 12 3 4 VOLUME OF TITRANT (ML. Fig. 14. — Sample N, forced oxidized coal carbonization series: Titration curves and derived graphs. The oxygen content of the oxidized coal was about twice that of the fresh coal. Up to 550 °C in the carbonization series the oxygen content was always significantly greater than for the fresh coal product at the same temperature. Thus it would ap- pear that an appreciable proportion of the oxygen absorbed was in groups that were fairly stable to heat. The oxidized coal showed a small de- crease in volatile matter (38.4 to 36.3 per- cent) and a large decrease in calorific value (14,452 to 11,923 Btu per pound, or 8029 to 6624 calories per gram) from that of 32 ILLINOIS STATE GEOLOGICAL SURVEY 100 200 300 400 500 600 CARBONIZATION TEMPERATURE- °C fresh coal. It had lost all swelling properties and the Gieseler plasticity was unobtain- able. Unconsolidated chars were obtained upon carbonization. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the forced oxidized coal carbonization series is shown in figure 14. The total acidity and component acidi- ties at each stage of the carbonization are given in table 10. Carboxyl groups formed in the oxidation could not be differentiated in titration from the stronger groups of the type present in the fresh coal, as was pos- sible for coal Sample M. For the purpose of calculating an approximate figure for acidic oxygen these original groups were assumed to be present up to 400 °C in the same amount as in the naturally oxidized coal carbonization series. One atom of oxy- gen per equivalent was assumed for them and for the groups of weaker acidic strength. The remainder of the stronger component acidity was assumed to be due to carboxyl groups and two atoms of oxy- gen per equivalent was assumed. At 450 °C and higher only one atom of oxygen per equivalent was allowed. These estimated acidic oxygen figures are also found in table 10. The oxidized coal itself gave a titration curve with two fairly sharp inflections. Up to 300°C two inflections were still present. The stronger and (particularly) the weaker component acidities corresponding to them had decreased in value. At 350° C a third inflection appeared in the curve corresponding to weaker groups than those originally present. There was a Fig. 15. — Sample N, forced oxidized coal car- bonization series: A. Milliequivalents of total and component acidities in each char. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization tempera- ture. Shaded areas represent distinguishable com- ponent acidities in order of decreasing acidic strength, the strongest at the top. NO. 6 COAL FROM JEFFERSON COUNTY 33 further decrease in the values of the origi- nal two component acidities. At 400 °C two inflections were present and they appeared to correspond to the original two component acidities decreased even further. At 450 °C they were still there, the stronger being about the same value, but the weaker having decreased to a very small value. At 500 °C and higher only one inflection was obtained. The corresponding acidity was very small. Figure 15a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char. The variation in the weight of total oxygen and acidic oxygen (based on the assumption stated above) through the carbonization series is shown in figure 15b. The acidic oxygen as a percentage of total oxygen was greatest in the oxidized coal itself and in the 200° char (about 52 percent), and decreased at a progressively faster rate through the series to a small value (7.6 percent) at 500° C. It increased slightly from 500°C to 600°C, no doubt due to loss of non-acidic oxygen in that range. At no stage of the carbonization did acidic oxygen appear to be converted into non-acidic oxygen or vice versa. Infrared Spectra The infrared spectra of fresh, naturally oxidized, and forced oxidized coal Sample N and some of the chars and cokes from them are shown in figure 16. Fresh Coal Series The broad absorption band due to hy- drogen-bonded O-H at about 3400 cm 1 de- creased and almost vanished between 350° and 400 °C as shown by the fluorolube spectra. There was little if any indication of aromatic C-H absorption just above 3000 cm 1 . Aliphatic C-H absorption of medium strength was found at 2900 cm 1 with a shoulder at 2830 cm 1 (slightly higher in fluorolube spectra). It decreased markedly between 350° and 400° C, was almost gone at 450 °C, but there was still a suggestion of its presence up to 600 °C. No carbonyl absorption was found in the 1700 cm 1 region. The strong band at 1610 cm 1 persisted throughout the series. The medium strength band due to ali- phatic CH 2 and CH 3 at 1440 cm 1 decreased above 350°C and was almost gone at 450°C. Very weak absorption at 1370 cm 1 , in- dicating CH 3 or cyclic CH 2 groups, per- sisted to 400° C, but seemed to have disap- peared at 450°C. A weak band at 1030 cm 1 possibly due to -C-O and/or -C-O-C- seemed to increase in intensity at 350° and 400° C and then decrease to 500 °C after which it could no longer be distinguished. Alternatively it may have been caused by silicate or other mineral matter. No definite assignment could be made for any other absorption bands. Naturally Oxidized Coal Series The spectrum of the naturally oxidized coal was very similar to that of the fresh coal. There was no carbonyl absorption at about 1700 cm 1 , indicating that no signifi- cant numbers of carboxyl groups were formed in the oxidation. Hydroxyl absorption at 3400 cm 1 did not seem to be as strong as in the fresh coal. It showed its greatest decrease between 300° and 400 °C although there was still evidence of it at 450°C. Aliphatic C-H at 2900 cm 1 with a shoulder at 2830 cm 1 also appeared less strong. It decreased from 300 °C and was hardly perceptible at 450° C and higher temperatures. The band at 1440 cm 1 due to aliphatic CH 2 and CH 3 groups also appeared weaker. It disappeared between 350° and 400°C. The 1030 cm 1 band (silicate and/or -C-O-C-, etc.) disappeared between 450° and 500° C. It did not increase at 350° and 400° as it had for the fresh coal. Forced Oxidized Coal Series Carbonyl absorption was indicated by a shoulder at 1675-1700 cm 1 on the strong 1600 cnv 1 band up to 400°C. 34 ILLINOIS STATE GEOLOGICAL SURVEY 3500 3000 2500 2000 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 FREQUENCY- CM"' Fig. 16. — Sample N, infrared spectra of the fresh and oxidized coals and some chars and cokes from them. NO. 5 COAL FROM GALLATIN COUNTY 35 Once again carboxyl groups appeared to be formed at the expense of aliphatic and naphthenic CH 2 groups. The 2900 cm 1 band was very weak and it was difficult to see any 1440 cm 1 absorption at all. The hydrogen-bonded O-H absorption in the 3400 cm 1 region was broad, but not very intense. Most of it appeared to have been lost by 500 °C in the carbonization series. SAMPLE O, NO. 5 COAL FROM GALLATIN COUNTY, ILLINOIS Sample O was a high-volatile A bitumi- nous coal from the No. 5 Coal in Gallatin County, Illinois. It was obtained from a slope mine in the side of a valley; the working face was well underground. Fresh Coal The analytical data for the carboniza- tion series of fresh Sample O are given in table 26. The carbon content (83.17 percent) was higher and the oxygen (7.52 percent) lower than for either Sample M or N. The ash (4.7 percent) was fairly low and the sulfur moderately high (2.18 percent), most (1.84 percent) being organic. The percentage of vitrinite was relatively low (80.5 percent) and of inertinite rather high (10.2 percent). Carbonization The free swelling index was fairly high (7) but the Gieseler maximum fluidity un- fortunately could not be measured because most of the coal swelled out of the cup and into the barrel. There was a large plastic range (390° to 476°). At 400 °C and above the carbonization products were frothy, very highly swollen cokes. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the fresh coal carboniza- tion series is shown in figure 17. The total acidity and component acidi- ties at each carbonization temperature are given in table 11, which also gives the total oxygen and acidic oxygen. The coal itself gave a smooth curve with two fairly sharp inflections. The total acidity was markedly less than for coal Samples M and N. This is in keeping with the coal's higher rank. However, most of the difference was in the weaker compo- nent acidity as the stronger was about the same value as that of coal Sample N. Up to 350 °C the form of the titration curve remained the same with two inflec- tions. The total acidity increased by a small amount to 200 °C and then decreased gradually to 350 °C. The stronger compo- nent acidity remained unchanged at 200 °C, decreased somewhat at 300 °C, and in- creased again to its original value at 350° C. The weaker component acidity remained fairly constant to 300 °C and then de- creased by 0.3 milliequivalents per gram to 350°C. The reproducibility of results obtained with the 400 °C coke was not very good. There appeared to be up to four compo- nent acidities which could not always be differentiated. For this reason the weaker ones were grouped together in calculating the mean. The total and stronger compo- nent acidities showed increases over the 350 °C values. The weaker component acid- ity was about the same as at 350° C, but rather uncertain. At 450 °C two inflections appeared in the curve, but again the reproducibility was not good. The stronger component acidity was slightly less than the 400 °C value, but the weaker was only half of the former value. The small inflection seen at 2.5 ml was a non-reproducible irregularity. At 500 °C and above only one inflection, corresponding to a small acidity, was ob- tained. Figure ISa shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char or coke. 36 ILLINOIS STATE GEOLOGICAL SURVEY 400 900- 800 200 300 700 300 2 3 12 VOLUME OF TITRANT (ML.) Fig. 17. — Sample O, fresh coal carbonization series: Titration curves and derived graphs. The variation in the weight of total oxy- gen and acidic oxygen throughout the car- bonization series is shown in figure ISb. The total oxygen decreased rapidly from 350° to 600 °C, the fastest rate being from 350° to 400°C. The acidic oxygen decreased from 200° to 500° C, the rate being greatest between 450° and 500 °C. Non-acidic oxygen in- creased at the expense of acidic in this range. The percentage of oxygen in acidic form was greatest at 400 °C (56 percent) where it was a little higher than in the coal itself. NO. 5 COAL FROM GALLATIN COUNTY 37 100 200 300 400 500 CARBONIZATION TEMPERATURE-°C 600 Fig. 18. — Sample O, fresh coal carbonization series: A. Milliequivalents of total and component acid- ities in each char or coke. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization temperature. Shaded areas represent distinguishable compo- nent acidities in order of decreasing acidic strength, the strongest at the top. Naturally Oxidized Coal Variation of Acidic Groups During Oxidation As shown in table 12 there was a drop in total acidity up to 21 days, followed by rather irregular behavior. After 48 days, three inflections were obtained in the titra- tion curve. After 64 days, the oxidized coal gave a smooth titration curve with two in- flections; the total acidity was slightly greater than that of the fresh coal, the in- crease being in the stronger component acidity. Carbonization The analytical data are given in table 27. The oxygen content of the oxidized coal was only slightly higher than that of the fresh coal. The volatile matter was un- changed, the calorific value showed a small decrease (15,053 to 14,761 Btu per pound or 8,363 to 8,200 calories per gram), the free swelling index had increased by one unit, but the Gieseler plasticity was unob- tainable because of high swelling. The chars and cokes obtained On car- bonization were very similar to those from the fresh coal. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the naturally oxidized coal carbonization series for naturally oxi- dized Sample O is shown in figure 19. The total acidity and component acidi- ties at each carbonization temperature are given in table 13 which also gives the per- centage contents of total and acidic oxygen. Up to 350 °C the form of the curve re- mained the same. There was a small de- crease in the weaker component acidity. A third inflection was obtained at 400°C. The total acidity was slightly greater than at 350° C although the two component acid- ities originally present had both decreased in value. 38 ILLINOIS STATE GEOLOGICAL SURVEY "NATURALLY OXIDIZED COAL VOLUME OF TITRANT (ML.) Fig. 19. — Sample O, naturally oxidized coal carbonization series: Titration curves and derived graphs. At 450 °C only two inflections appeared. The total break in the curve was less than at 400°C. The weaker component acidity appeared to correspond with the weakest at 400 °C and the stronger seemed to have come from the strongest and second strong- est at 400°C. At 500°C and above only one inflection was obtained. The acidity appeared to cor- respond with what was left of the stronger at 450°C. Figure 20a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char or coke. NO. 5 COAL FROM GALLATIN COUNTY 39 2.0 r 100 200 300 400 500 CARBONIZATION TEMPERATURB-C 600 Fig. 20. — Sample O, naturally oxidized coal car- bonization series: A. Milliequivalents of total and component acidi- ties in each char or coke. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization temperature. The variation in the weight of total and acidic oxygen throughout the carbonization series is shown in figure 20 b. The weight of total oxygen fell from 300° to 600 °C, the rate being greatest between 400° and 450 °C. The weight of acidic oxygen de- creased between 300° and 350° C and then rose slightly to 400 °C with the appearance of the weakest acidic groups. From there it fell sharply to a low value at 500 °C. Some appeared to be converted into a non-acidic form between 450° and 500 °C. The percentage of oxygen in acidic form was at a maximum at 400 °C (58 percent), where it was a little higher than in the coal itself. Forced Oxidized Coal Variation of Acidic Groups During Oxidation As shown in table 14 the total acidity of Sample O during oxidation increased from 2.54 to 4.47 milliequivalents per gram over the 47-day period. The increase in the first 14 days was more than twice that in the rest of the time. The stronger component acidity had more than doubled in the first two weeks, trebled after 27 days, and con- tinued to increase more slowly after that. The weaker component acidity increased by about one third in the first 14 days and then remained fairly constant to 36 days before decreasing by a small amount in the final 11 days. Carbonization The analytical data for the carbonization series of forced oxidized Sample O are given in table 28. The oxygen content of the oxidized coal was almost two and a half times that of the fresh coal. Throughout the series the oxygen con- tent was always markedly greater than for the fresh coal product at the same tem- perature. Shaded areas represent distinguishable compo- nent acidities in order of decreasing acidic strength, the strongest at the top. 40 ILLINOIS STATE GEOLOGICAL SURVEY 800- 300 12 3 4 -. 2 3 4 5 12 3 4 1000 \ 350° CHAR V 400° CHAR /-n 450° CHAR 900 \ 800 \ 700 \ 600 V^T 500 A A ^ . 400 - A A / M AvA 300 200 - Av v^ / ^^ / ^— 0.190 N / 0.192 N 0.I92N 1 c 1 ■ UJ|> 500 400 12345 1234 1234 VOLUME OF TITRANT (ML.) Fig. 21. — Sample O, forced oxidized coal carbonization series: Titration curves and derived graphs. The oxidized coal showed a decrease in volatile matter (42.5 to 35.7 percent) and a large decrease in calorific value (15,053 to 12,314 Btu per pound or 8363 to 6841 calories per gram) from that of the fresh coal. It had lost all measurable swelling and plastic properties. The solid carbonization products were unconsolidated chars. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the forced oxidized coal carbonization series is shown in figure 21. NO. 5 COAL FROM GALLATIN COUNTY 41 The total acidity and component acidi- ties at each stage of the carbonization are given in table 15. For the oxidized coal itself there were three inflections in the titration curve in three titrations out of four. The position of the middle one was not very reproduci- ble, so for the mean this inflection was ignored and only a stronger and weaker component acidity given. Carboxyl groups formed in the oxidation are believed to ac- count for part of the stronger component acidity, the remainder being due to groups of the type which give rise to such acidity in the fresh coal. At 200 °C the middle inflection was weak or absent, so only two component acidities were considered. The stronger had in- creased slightly but the weaker showed a definite decrease. At 300° C the stronger component acidity had decreased markedly, the weaker by a small amount, and there was a new faint inflection indicating the presence of very weakly acidic groups. The component acidity due to these ex- tremely weak groups had increased three- fold at 350° C. The original two component acidities had decreased by small amounts. The total acidity was higher than in the coal itself. At 400 °C three inflections were once again obtained in the titration curve, but the component acidities had all decreased, particularly that due to the very weak groups. The total acidity was only about half that at 350°C. Only two inflections were obtained at 450 °C, the second being rather faint. These appeared to correspond to the first two inflections at 400° C. At 500 °C and above only one inflection, corresponding to small acidity, was ob- tained in the titration curve. For the calculation of acidic oxygen, carboxyl groups were assumed to be re- sponsible for the strongest component acidity in excess of that found in the nat- urally oxidized series for carbonization products obtained up to 400° C. Infrared spectra indicated their presence up to that temperature. Two oxygen atoms per equiv- alent were assumed for such groups and one per equivalent for the remainder. Figure 22a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char. The variation in the weight of total oxy- gen and acidic oxygen (based on the as- sumption stated above) through the car- bonization series is shown in figure 22b. The acidic oxygen as a percentage of total oxygen was greatest at 350° C (70 per- cent) due to the presence of the extremely weak groups at that temperature. Between 300° and 350°C acidic oxygen increased at the expense of non-acidic, but between 350° and 400 °C the reverse was true. Infrared Spectra The infrared spectra of fresh, naturally oxidized, and forced oxidized coal Sample O and some of the chars and cokes from them are shown in figure 23. Fresh Coal Series Very broad absorption due to hydrogen- bonded O-H (and N-H?) groups was seen up to 350° C. The flat "peak" was at about 3400 cm 1 . A small number of aromatic C-H groups was indicated by a very faint absorption peak at about 3050 cm 1 up to 500°C. Aliphatic and/or naphthenic C-H ab- sorption of medium strength was found at 2930 cm 1 with a shoulder at 2870 cm 1 up to 350°C. It was very weak at 400°C and could not be seen at higher temperatures. No C:0 absorption was found in the 1700 cm 1 region. The strong and broad 1600 cm 1 band persisted throughout the series. The medium strength band due to ali- phatic and/or naphthenic CH 2 and CH 3 groups at 1440 cm 1 decreased between 350° and 400 °C, and at 450 °C and above could not be distinguished from the general ab- sorption. The weak peak at 1370 cm 1 due to CH, or cyclic CH 2 groups could not be seen above 400°C. 42 ILLINOIS STATE GEOLOGICAL SURVEY The broad absorption from 1200 to 1000 cm -1 , particularly noticeable in the 500°, 550°, and 600°C cokes, may have indicated aromatic ethers, but may also have been largely due to mineral matter. The weak peak at 1030 cm 1 likewise may have been caused by ethers and/or kaolinite. It could be distinguished up to 450°C. Naturally Oxidized Coal Series The broad hydrogen-bonded O-H ab- sorption at about 3400 cm 1 decreased be- tween 300° and 350° C. It could not be seen after 400°C. Slight aromatic C-H absorption could be distinguished at least up to 400° C at about 3060 cm 1 . Medium strength aliphatic and/or naph- thenic C-H absorption decreased above 300°C, but was still evident up to 450°C. It occurred at about 2940 cm 1 with a shoul- der at about 2880 cm 1 . The strong broad band with its peak from 1620 to 1605 cm- 1 persisted through- out the series. The band of medium strength with peak at 1450 - 1440 cm 1 due to CH 2 and CH 3 groups decreased gradually to 400 °C. It may have still been present at 450° C, but was gone at higher temperatures. The weak band at 1375 cm 1 due to CH 3 and cyclic CH 2 groups persisted to 400 °C after which its presence was uncertain. The bands in the 1200 to 1000 cm 1 re- gion, which merged into general absorp- tion at higher temperatures, were most probably due to aromatic CO structures (e.g., ethers) with interference from min- eral matter. The three very weak bands at about 860, 810, and 750 cm 1 may have been due to variously substituted benzene structures. Fig. 22. — Sample O, forced oxidized coal car- bonization series: A. Milliequivalents of total and component acidities in each char. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization tempera- ture. Shaded areas represent distinguishable com- ponent acidities in order of decreasing acidic strength, the strongest at the top. 100 200 300 400 500 CARBONIZATION TEMPERATURE-°C 600 NO. 5 COAL FROM GALLATIN COUNTY 43 90 80 70 60 > " — i ■ — p^ — ' — ■ — ■ — ■ — ■ — « — *- — ■ ■ ■ ■ ■ '■■ \> FRESH COAL, SAMPLE 50 *— ^^v r^^ — ^ 40 30 20 \f\r r^J 80 70 60 50 40 80 r 70 -'' 60 ■ 50 • 80 ■ 70 60 80 70 ■'' 60 50 /■*" •V 350° CHAR .•*' — ''V "NATURALLY" oxidized coal, sample 3500 3000 2500 2000 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 600 700 FREQUENCY -CM"' Fig, 23.— Sample O, infrared spectra of the fresh and oxidized coals and some chars and cokes from them. 44 ILLINOIS STATE GEOLOGICAL SURVEY 500 VOLUME OF TITRANT (ML.) Fig. 24. — Sample P, fresh coal carbonization series: Titration curves and derived graphs. The 750 cm 1 band was seen up to 600 °C, the others to at least 400° C. Forced Oxidized Coal Series The spectra showed a very strong shoul- der at 1700 cm 1 on the 1600 cm 1 band due to C:0 in carboxyl groups formed in the oxidation. The shoulder decreased in in- tensity above 200° C, being seen last at 450 °C where it was very weak. The bands due to aliphatic and/or naph- thenic C-H and CH 2 at 2940 and 1440 cm 1 were markedly decreased from those in the spectrum of the naturally oxidized coal. The behavior of the various other ab- sorption bands with increase of carboniza- tion temperature followed much the same pattern as before. POCAHONTAS COAL FROM WEST VIRGINIA 45 sample p, pocahontas coal from Mcdowell county, west virginia Sample P was a low-volatile bituminous coal from an underground mine operating in Pocahontas No. 3 seam in McDowell County, West Virginia. Fresh Coal The analytical data for the carboniza- tion series of fresh Sample P are given in table 29. This was a very high rank bituminous coal (91.23 percent carbon) used in the production of metallurgical coke. Both the ash (2.4 percent) and sulfur (0.56 per- cent) contents were low. Practically all the sulfur was in organic form. 100 200 300 400 500 CARBONIZATION TEMPERATURE-'C 600 Fig. 25. — Sample P, fresh coal carbonization series: A Milliequivalents of total and component acidi- ties in each char or coke. B. Variation of weight of oxygen (acidic and non- acidic) with carbonization temperature. Shaded areas represent distinguishable component acidities in order of decreasing acidic strength, the strongest at the top. The percentage of vitrinite was moder- ate (85.6 percent), inertinite fairly large (13.4 percent) and no exinite was present. Carbonization The free swelling index was high (9), but the Gieseler maximum fluidity low (85 dial divisions per minute) . The plastic range was very short (459-484 °C). At 450 °C and above, highly swollen cokes were obtained but they were moder- ately hard. Variation of Acidic Groups During Carbonization The titration curves and derived graphs from the fresh coal carbonization series are shown in figure 24. The total acidity and component acidi- ties at each carbonization temperature are given in table 16, which also gives the total oxygen and acidic oxygen. Up to 300 °C the curve showed two in- flections which could just be differentiated. The total acidity was very low in compari- son with the other coals studied. The stronger component acidity in- creased by a small amount to 200° C and then decreased slightly to 300 °C. The weaker component acidity decreased by a similar small amount to 200 °C and then re- mained substantially the same at 300° C. At 350°C, 400°C, and 450°C only one in- flection was obtained. The acidity de- creased by a small amount to 350 °C, re- mained the same at 400 °C and then in- creased again. At 500 °C two inflections were obtained and the component acidities were very close to those obtained at 300° C. At 550°C and 600° C only one inflection was found. Figure 25a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char or coke. The variation in the weight of total oxy- gen and acidic oxygen throughout the car- bonization series is shown in figure 25b. The weight of total oxygen varied in an irregular manner that seemed to indicate 46 ILLINOIS STATE GEOLOGICAL SURVEY 700 'NATURALLY OXIDIZED COAL - 600 300 -200 ais 600 300 200 2 3 12 3 VOLUME OF TITRANT (ML.) Fig. 26. — Sample P, naturally oxidized coal carbonization series: Titration curves and derived graphs. error in determination. The inherent error in oxygen content obtained by difference would be greatest in such a low-oxygen coal. The weight of acidic oxygen decreased slightly to 300 °C and then fell suddenly to 350 °C with the loss of the stronger com- ponent acidity. It was steady to 400°, rose slowly to 450°, then had a small sharp rise to 500 °C. It fell off to a very low value at 550° and 600°C. The percentage of oxygen in acidic form was a maximum in the coal itself (54 per- cent), decreased to 400°, increased to 450° and 500 °C (44 percent) and then fell off to a low proportion. POCAHONTAS COAL FROM WEST VIRGINIA 47 Naturally Oxidized Coal Variation of Acidic Groups During Oxidation The total acidity fell from 0.83 to 0.62 milliequivalents per gram in the 64 days. Both component acidities decreased by small amounts. Carbonization The analytical data are given in table 30. The oxidized coal and the chars and cokes from it apparently had slightly lower oxygen contents than the fresh coal and its corresponding carbonization products. This may have been due to error in the de- termination of oxygen by difference. The oxidized coal had slightly higher volatile matter and slightly lower calorific value than the fresh coal, the free swelling index was unchanged, but the Gieseler plasticity had decreased from 85 to 22 dial divisions per minute and the solidification temperature was 504 °C whereas originally it was 484°C. 100 200 300 400 500 CARBONIZATION TEMPERATURE-°C 600 Fig. 27. — Sample P, naturally oxidized coal carboni- zation series: A. Milliequivalents of total and component acid- ities in each char or coke. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization temperature. Shaded areas represent distinguishable component acidities in order of decreasing acidic strength, the strongest at the top. The chars and cokes obtained on car- bonization were similar to those from the fresh coal. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the naturally oxidized coal carbonization series is shown in figure 26. The total acidity and component acidi- ties at each carbonization temperature are given in table 17, which also gives the total oxygen and acidic oxygen. Up to 300 °C the curve showed two in- flections which could just be differenti- ated. When the solvent blank was sub- tracted the stronger component acidity was found to be very small, decreasing to a neg- ligible quantity at 300°C. At 350°C and above only one inflection was obtained. The total acidity remained fairly con- stant from 300° to 500 °C and then de- creased at 550° and 600°C. The starting E.M.F. remained fairly high throughout the series. In many cases there were non-reproducible irregularities in the tails of the titration curves. Figure 27a shows diagrammatically the number of milliequivalents of acidity in each char or coke. The variation in the weight of total oxy- gen and acidic oxygen throughout the car- bonization series is shown in figure 27 b. The weight of total oxygen varied in an irregular manner which once again most probably indicated error due to oxygen de- termination by difference. The weight of acidic oxygen apparently increased by a small amount to 200°C, fell fairly rapidly to 350 °C where the small amount of the stronger component acidity could no longer be differentiated, rose slightly to 500 °C and then decreased again to 550 and 600°C. The percentage of oxygen in acidic form was a maximum in the 200 °C char (60 per- cent), decreased to 400 °C (31 percent), increased slightly to 450 °C (34 percent) and 500°C (33 percent) and then fell off to about half this proportion at 550° and 600 °C. 48 ILLINOIS STATE GEOLOGICAL SURVEY 600 2 3 12 VOLUME OF TITRANT (ML) Fig. 28. — Sample P, forced oxidized coal carbonization series: Titration curves and derived graphs. Forced Oxidized Coal Variation of Acidic Groups During Oxidation As shown in table 18 the total acidity in- creased to almost twice its original value over the 47-day period. However, the in- crease in the first 37 days was less than in the final ten, perhaps indicating that there was an initial decrease corresponding to natural oxidation. The stronger component acidity showed a larger percentage increase than the weaker. The latter at the end of the period could be differentiated into two separate component acidities, each of which had al- most the same value as the strongest (0.55 milliequivalents per gram). POCAHONTAS COAL FROM WEST VIRGINIA 49 Carbonization The analytical data for the carboniza- tion series are given in table 31. The oxygen content of the oxidized coal was more than twice that of the fresh coal. Up to 450 °C in the carbonization series the oxygen content was significantly more than in the fresh coal product at the same tem- perature. 100 200 300 400 500 CARBONIZATION TEMPERATURE-°C 600 Fig. 29. — Sample P, forced oxidized coal carboniza- tion series: A. Milliequivalents of total and component acid- ities in each char. B. Variation of weight of oxygen (acidic and non-acidic) with carbonization temperature. Shaded areas represent distinguishable component acidities in order of decreasing acidic strength, the strongest at the top. The volatile matter was the same as for the fresh coal. The calorific value had de- creased (15,647 to 14,933 Btu per pound 01 8693 to 8296 calories per gram). The oxi- dized coal had lost all swelling and agglom- erating properties. Carbonization yielded unconsolidated chars. Variation of Acidic Groups During Carbonization A selection of titration curves and de- rived graphs from the forced oxidized coal carbonization series is shown in figure 28. The total and component acidities are given in table 19, together with total and acidic oxygen. The coal itself gave a titration curve with three inflections, the corresponding com- ponent acidities being roughly equal in magnitude. From 200° to 400 °C two inflections were obtained, the first corresponding to the strongest component acidity in the coal it- self, gradually decreasing in value. The second appeared to correspond to what was left of the weaker two in the coal, differ- entiation being no longer obtained. It de- creased slowly to 350 °C and more quickly to 400° C. At 450 °C and higher temperatures only one inflection was obtained. The total acidity continued to decrease, but at 450° C was higher than either of the components alone at 400 °C, indicating that groups of both strengths were still present, but differ- entiation was no longer possible. The percentage of oxygen in acidic form was a maximum in the coal itself (43 per- cent). Figure 29a shows diagrammatically the number of milliequivalents of the compo- nent acidities in each char. The variation in the weight of total oxy- gen and acidic oxygen throughout the car- bonization series is shown in figure 29b. The value for total oxygen at 600 °C is ob- viously too high. This may have been due to error in determination by the difference method or to further oxidation before an- alysis despite precautions. Since the oxi- dized coal did not appear to show carbonyl 50 ILLINOIS STATE GEOLOGICAL SURVEY 3000 2500 2000 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 FREQUENCY- CM Fig. 30. — Sample P, infrared spectra of the fresh and oxidized coals and some chars and cokes from them. POCAHONTAS COAL FROM WEST VIRGINIA 51 absorption in its infrared spectrum (at about 1700 cm 1 ) and exhibited no notice- able solubility in sodium hydroxide solu- tion, it was concluded that carboxyl groups had not been formed to any appreciable ex- tent in the oxidation. Accordingly acidic oxygen was calculated on the basis of one oxygen atom per equivalent of acidity. Infrared Spectra The infrared spectra of fresh, naturally oxidized, and forced oxidized coal Sample P and some of the chars and cokes from them are shown in figure 30. Fresh Coal Series The hydrogen-bonded O-H absorption at about 3400 cm 4 was very weak even at the start of the series, as shown by the fluoro- lube spectra at 200° and 300°C. That shown by the potassium bromide spectra must have been largely due to water. Weak absorption due to aromatic C-H appeared at about 3030 cm 1 up to 450° C. For some reason it showed up better in the fluorolube spectra than in the potassium bromide spectra. Aliphatic and/or naphthenic C-H ab- sorption appeared at about 2910 cm 1 with a weak shoulder at about 2840 cm- 1 . It was stronger than the aromatic C-H absorption, but still rather weak. It decreased in in- tensity between 400° and 450°C but was barely perceptible at 500 °C and higher temperatures. The strong 1615 cm 1 band persisted throughout the series with gradually de- creasing intensity. Aliphatic and/or naphthenic CH 2 and CH 3 groups were indicated by medium strength absorption at about 1435 cm 1 . They were present to 450 °C, but seemed to have been eliminated at 500°C. An extremely weak peak at 1375 cm 1 could be distinguished in most of the spec- tra up to 450° C. It indicated CH 3 or cyclic CH 2 groups in small numbers. Three very weak bands at about 865, 795 and 745 cm 1 may have indicated benzene rings substituted in different ways. They were most noticeable at 400° and 450 °C, could just be distinguished at 500°C, but could no longer be seen at 550° and 600 °C. Naturally Oxidized Coal Series Little hydrogen-bonded O-H absorption at about 3500 cm 1 could be seen even in the coal itself. Very weak aromatic C-H absorption at about 3060 cm 1 decreased above 400 °C but even at 600 °C a suggestion of it was still apparent. The aliphatic and/or naphthenic absorp- tion at 2940 cm 1 with a shoulder at 2870 cm 1 was stronger. It began to decrease from 300 °C and could no longer be seen at 500°C. The "coal band" at about 1600 cm 1 per- sisted throughout the series. Medium strength absorption at about 1435 cm 4 (CH 2 and CH 3 groups) was seen up to 500° C after which it merged with general absorption in the 1450-1350 cm 1 region. A very weak peak at 1370 cm 1 (CH 3 or cyclic CH 2 ) was seen up to 400°C. The three weak bands indicating substi- tuted benzene structures appeared at about 865, 805, and 750 cm 1 and could be seen in all members of the series. Forced Oxidized Coal Series Hydrogen-bonded O-H was indicated by broad absorption of low intensity at about 3500 cm 1 . It became less noticeable as the temperature increased. Weak aromatic C-H absorption was seen up to 450° C at 3050 cm 1 . The weak aliphatic and/or naphthenic C-H band at about 2930 cm 1 with a shoul- der at about 2860 cm 1 persisted up to 450° C. For some reason, it was stronger in the potassium bromide spectra than in the fluorolube, where it was only about the same intensity as the aromatic C-H. There was no appreciable absorption due to C:0 at about 1700 cm 1 although the 1600 cm 1 did seem to be broadened on that side. It would appear that few, if any, carboxyl groups were formed in the oxida- tion. This is supported by the failure of the oxidized coal to show pronounced caus- tic solubility. OZ ILLINOIS STATE GEOLOGICAL SURVEY The strong, broad 1600 cm 1 band was seen throughout the series. The medium strength CH 2 and CH 3 ab- sorption at about 1435 cm 1 and the very weak CH 3 or cyclic CH 2 band at about 1375 cm 1 were seen up to 500 °C where they merged into the general absorption. The three weak bands from substituted benzene structures were seen at about 870, 815 and 750 cm 1 throughout the series. SAMPLE Q, WILLIS COAL FROM GALLATIN COUNTY, ILLINOIS Sample Q was a high-volatile A bitumi- nous coal of the Willis seam in Gallatin County, Illinois, and was obtained by Dr. E. D. Pierron of this laboratory for use in another investigation. It was not carried through the oxidation and carbonization series applied to previous coals, but was ti- trated fresh to get additional data for the comparison of the acidities of coals of vari- ous ranks. This coal is said to be the highest rank coal known in Illinois. Analytical data are given in table 32. It is a high sulfur coal (3.30 percent), but most of this sulfur (2.52 percent) is pyritic. Titration Experiments On titration two inflections were ob- tained corresponding to a total acidity of 1.96 milliequivalents per gram, made up of a stronger component (0.46 milliequiva- lents per gram) and a weaker component of 1.50 milliequivalents per gram. RISE IN E.M.F. BEFORE TITRATION The initial E.M.F., as soon as the indi- cator electrode was inserted, was usually about 550 to 600 mv. In many cases it rose steadily to about 700 mv in about 2 to 2 1/2 hours and then rose very quickly to more than 900 millivolts. However, for a number of chars and cokes obtained at 450 °C and higher temperatures, this fur- ther rise did not take place. At first it was thought that a delayed action swelling effect might be responsible for the sudden increase in E.M.F., but this was disproved as follows. A sample which was known to show the effect was put into suspension in the ethylenediamine in the titration flask and stirred with a magnet- impelled stirrer overnight. Next morning the flask was fitted to the apparatus and the electrode inserted. The E.M.F. was only 550 mv. However, it began to rise as had been noted before, slowly at first and rapidly after about two hours, until it lev- elled off at about 925 mv. Thus, as the sample had had ample time to swell over- night, it must have been some effect on the indicator electrode which caused the sud- den rise in E.M.F. Residual Acidity at 550° and 600 °C In all the series it was found that 0.3 to 0.4 milliequivalents per gram of acidity still remained after carbonization to 600° C. At 550 °C the quantity was usually slightly higher. It was originally thought to be a rem- nant of the weaker component acidity. This was suggested by the lower half neu- tralization potential which has been used as an indication of acidic strength (cf. A. J. Martin, 1957). Later it was found that the half neutralization potential varied considerably, even in different titrations of the same sample. Therefore the 500 °C cokes from each of the fresh coals were titrated in admixture with benzoic acid. Only one inflection was obtained in each case, indicating that the residual acidic groups were of about the same strength as benzoic acid in ethylene- diamine. They would thus seem to be remnants of the original stronger rather than weaker component acidity, at least for samples M, N, and O. Sample P may be an exception in this regard, as the original weaker component acidity could barely be differentiated from the stronger, which was present in very small amount. When the fresh coal was titrated with benzoic acid only one inflec- tion was obtained, showing that both com- ponent acidities were strong enough to WILLIS COAL FROM GALLATIN COUNTY b.^> titrate with it. The residual acidity could be derived from either, but as the stronger is present in small amount in the coal it may well come from the weaker. Of course the possibility also exists that the residual acidity could be due to new strongly acidic groups formed in the py- rolysis and having no connection with groups originally present in the coal. 40 5 >- 3.0 ao I 1.0 5 10. 15 20 25 OXYGEN CONTENT- D.A.F. y 5.0 10.0 OXYGEN CONTENT- D.A.F Fig. 31. — Variation of the acidities of the fresh coals with carbon and oxygen content. A. Total acidity vs. carbon content. B. Total acidity vs. oxygen content. C. Weaker component acidity vs. oxygen content. CAUSTIC SOLUBILITIES OF THE FRESH AND OXIDIZED COALS Each of the fresh and oxidized coals (5 grams) was brought to the boil in 10 per- cent sodium hydroxide solution (100 ml) and the suspension filtered through two layers of filter paper. All samples gave colorless or light straw- colored solutions except forced oxidized coals M, N, and O, which gave very dark brown solutions typical of alkaline hu- mates. Even in the cold these samples gave brown solutions. The failure of forced oxidized coal Sam- ple P to show this pronounced caustic solu- bility is noteworthy as it probably indi- cates that no significant formation of car- boxyl groups took place during oxidation. RELATION OF ACIDITY OF FRESH COALS TO RANK In figures 3 la and 316, the total acidities of the fresh coals are plotted against car- bon content and oxygen content. For com- parison the "vitrain curves," according to J. D. Brooks and T. P. Maher (1957), are shown in the same figures. Coals N and P fall just above the carbon curve whereas the other coals fall below it. The coals fall closer to the oxygen curve, but Samples M and O are noticeably be- low it. These are the coals with the highest percentages of organic sulfur. The stronger component acidity was of the same order (0.60 to 0.65 milliequiva- lents per gram) for the three lowest rank coals but decreased for coals with increase in rank. Figure 31c shows the weaker component acidities graphed against oxygen content. Here also coals M and O fall below the curve. 54 ILLINOIS STATE GEOLOGICAL SURVEY SUMMARY AND CONCLUSIONS Fresh Coals All five coals behaved as dibasic acids in ethylenediamine. The differentiation be- tween strongly acid and weakly acid groups was distinct for the high-volatile coals, less so for the low-volatile coal of low acidity. The total acidity generally correlated with rank, decreasing as the rank increased. The weaker component acidity appeared to correlate with rank better than the stronger. Coals with a large content of organic sulfur had lower acidity than might be expected on the basis of their carbon or even oxygen content. Carbonization of Fresh Coals In the carbonization of the three high- volatile coals the acidity due to the original two component acidities began to decrease above 200° C. The greatest decrease was from 400° to 500 °C, but, after 400° or 450 °C, differentiation between them was no longer obtained. Groups of weaker strength made their appearance as early as 300° C in one coal and at 400 °C for the other two. They persisted to 500 °C for the two coals of lowest rank. The tendency of the weak groups to appear seemed to di- minish as the rank increased, and they were not found in the carbonized products from the low-volatile coal. However, in the low- volatile series groups of the same strength as those of the original weaker acidity (which had vanished above 300 °C) reap- peared at 500 °C with a resulting small in- crease in total acidity at that temperature. Natural Oxidation Oxidation at room temperature in gen- eral caused an initial decrease in acidity fol- lowed by a slow rise. The over-all result was a small decrease except for Sample O where there was a slight increase. Chemical and physical properties were not greatly changed except for Gieseler plasticity, which was decreased. This was most marked for Sample M where the abil- ity to form frothy cokes at 400° and 550 °C was also lost. Effect of Natural Oxidation on Carbonization Oxidation at room temperature did not cause much change in the cokes obtained on carbonization, except for Sample M as stated above. There seemed to be a tendency for nat- ural oxidation to lessen the number of very weak groups formed in carbonization and to narrow the temperature range over which they were found. The acidity remaining at 500 °C was less for the oxidized coal series than for the fresh, except for Sample O where the two series were very similar. Forced Oxidation Oxidation at 110°C increased the oxygen content to more than double its original value in all samples, but Sample O (high- volatile A bituminous) showed the largest percentage increase. There were decreases in volatile matter and calorific value, and all measurable plastic and swelling prop- erties were lost. Sample O showed the largest percentage increase in total acidity. However, in all the oxidized coals the percentage of oxy- gen in acidic form was somewhat less than in the fresh coals, so more of the oxygen must have been taken up into non-acidic than acidic structures. In Samples M and N practically all of the increase was in the stronger component acidity. For the three high-volatile coals the infrared spectra indicated the forma- tion of carboxyl groups which would be re- sponsible for at least part of this increase. In Sample M the stronger component acid- ity could eventually be differentiated into two separate acidities, the weaker of which appeared to be due to carboxyl groups. In coals O and P the weaker acidity showed an appreciable increase although that of the stronger acidity was still greater. SUMMARY AND CONCLUSIONS 55 Effect of Forced Oxidation on Carbonization Carbonization of the forced oxidized coals gave only chars for all samples. The increase in the stronger component acidity, which was most probably due large- ly to the formation of carboxyl groups in the three high-volatile coals, was thought to be related to loss of coking ability. The acidity remaining at 500° C was less for the oxidized coal series than for the fresh, except for Sample O where it was about the same. The number and amount of very weak acidic groups formed in the carbonization of the high-volatile coals and the tempera- ture ranges over which they persisted were different in the fresh and oxidized coals. However, no simple pattern in the varia- tions could be seen. Nature of the Acidic Groups The presence of groups of two distinct acidic strengths, particularly in the fresh high-volatile coals, was noteworthy. There was no evidence that the stronger groups were carboxyl. Perhaps they were phenolic groups with their strength enhanced be- cause of their positions in the structure. The weaker groups would be those of more normal strength. It was noted that no indication of hydro- peroxides could be detected in the oxidized coals. According to the work of A. J. Mar- tin (1957) such groups would be expected to titrate as very weak acids. The presence of carboxyl groups was in- dicated in the high-volatile coals after forced oxidation. The nature of the very weak groups, formed in the carbonization of the high- volatile coals, is not known. Perhaps they are very weak phenolic groups formed dur- ing decomposition. The infrared spectra were not found to be very satisfactory for following the be- havior of the hydroxyl groups. Even when water was excluded the absorption band was so broad that even semi-quantitative appraisal was difficult. The possibility of the presence of some other functional groups capable of titra- tion should not be overlooked, but their contribution, if any, is likely to be small. Acidity associated with nitrogen or hydro- carbon structures may possibly be partly re- sponsible for the small amount found after carbonization to 600° C. 56 ILLINOIS STATE GEOLOGICAL SURVEY REFERENCES Bergmann, G., Huck, G., Karweil, J., and Luther, H., 1957, Infrared spectra of bituminous coals: Brennstoff-Chemie, v. 38, p. 193-9. Blom, L., Edelhausen, L., and Krevelen, D. W. van, 1957, Chemical structure and properties of coal. XVIII — Oxygen groups in coal and related prod- ucts: Fuel, v. 36, p. 135-53. Brooks, J. D., and Maher, T. P., 1954, Direct titra- tion of acidic groupings in coal: Research (Lon- don), v. 7, p. S30-31. Brooks, J. D., and Maher, T. P., 1957, Acidic oxy- gen-containing groups in coal: Fuel, v. 36, p. 51- 62. Brown, J. K., and Wyss, W.F., 1955, Oxygen groups in bright coals: Chemistry & Industry, p. 1188. Friedel, R. A., and Queiser, J. A., 1956, Infrared analysis of bituminous coals and other carbona- ceous materials: Anal. Chem., v. 28, p. 22-30. Glenn, R. A., and Peake, Janet T., 1955, Titration of phenolic esters in ethylenediamine: Anal. Chem., v. 27, p. 205-9. Ihnatowicz, A., 1952, Determination of oxygen groups in bituminous coals: Prace Glownego Inst. Gornictwa, Comm. No. 125, 39 pp.; British Coal Utilisation Research Assn. Bulletin, 1953, v. 17, p. 301. Katz, M., and Glenn, R. A., 1952, Sodium amino- ethoxide titration of weak acids in ethylenedia- mine. Application to determination of phenols in coal hydrogenation oils: Anal. Chem., v. 24, p. 1157-63. Krevelen, D. W. van, and Schuyer, J., 1957a, Coal Science — Aspects of coal constitution, p. 211, El- sevier Publishing Co., D. van Nostrand Co., Inc., New York, U. S. Distributors. Krevelen, D. W. van, and Schuyer, J., 1957b, ibid., chaptei VII, p. 185. Macdonald, P., 1957, Private communication to T. P. M. Fuel Research Station, London, Eng- land. Maher, T. P., and Yohe, G. R., 1958, Acidic prop- erties of tetrazole derivatives in a non-aqueous medium: Jour. Organic Chem., v. 23, p. 1082. Martin, A. J., 1957, Potentiometric titration of hydroperoxides and peracids in anhydrous ethyl- enediamine: Anal. Chem., v. 29, p. 79-81. Mazumdar, B. K., Anand, K. S., Roy, S. N., and Lahiri, A., 1957, Mechanism of the oxidation of coal: Brennstoff-Chemie, v. 38, p. 305-7. Moss, M. L., Elliott, J. FL, and Hall, R. T., 1948, Potentiometric titration of weak acids in anhy- drous ethylenediamine: Anal. Chem., v. 20, p. 784-8. Uporova, E. P., and Rafikov, S. R., 1956, Deter- mination of carboxyl and phenolic groups in coal: Izvest. Akad. Nauk Kazakh. S. S. R., Ser. Khim., No. 9, p. 23-32; Chem. Abst., 1956, v. 50, col. 8992i. Walker, W. E., Henry, J. P., and Davis, H. G., 1958, Titration of acidic functional groups in coal: Paper presented before the Divison of Gas and Fuel Chemistry, American Chemical Society, Urbana, Illinois, May 15, 1958. Yohe, G. R., and Blodgett, Eva O., 1947, Reaction of coal with oxygen in the presence of aqueous sodium hydroxide. Effect of methylation with dimethyl sulfate: Jour. Am. Chem. Soc, v. 69, p. 2644-8; reprinted as Illinois State Geol. Sur- vey Circ. 139. Yohe, G. R., and FIarman, C. A., 1941, The oxidiz- ing power of Illinois coal. I. The reaction with titanous chloride: Jour. Am. Chem. Soc, v. 63, p. 555-6; reprinted as Illinois State Geol. Survey Circ. 70. TABULAR DATA 57 APPENDIX TABULAR DATA Table 1. — Sample M, Fresh Coal Carbonization Series Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen (Assuming one oxygen atom per equivalent) Fresh Coal Mean 3.35 3.37 3.36 0.78 0.85 0.82 2.57 2.52 2.54 200 Mean 3.52 3.55 3.54 0.97 0.98 0.98 2.55 2.57 2.56 300 Mean 3.30 3.21 3.26 0.82 0.77 0.80 2.48 2.44 2.46 350 Mean 2.86 2.86 2.86 0.70 64 0.67 2.16 2.22 2.19 400 Mean 3.03 3 00 3.02 0.63 0.73 0.68 1.61 1.58 1.60 450 Mean 3 45 3.45 3.45 2.01 1.99 2.00 500 Mean 3.06 3.00 3 03 0.78 0.82 0.80 550 Mean 58 59 59 0.58 59 0.59 600 Mean 32 37 35 32 37 0.35 1.68 1.65 0.79 0.69 0.74 0.87 0.87 0.57 1.46 0.58 2.18 0.60 0.58 10.18 10.75 10.55 9.49 8.45 7.1 6.14 5.69 4.36 5.38 5.66 5.22 4.58 4.83 5.52 4.85 94 56 52.8 52.7 49.5 48.3 57.2 77.6 79 16 5 12.8 58 ILLINOIS STATE GEOLOGICAL SURVEY Table 2. — Sample M, Variation of Acidity During Natural Oxidation. Values in milliequivalents per gram of dry, ash-free coal. Time exposed (days) Total aciditv Component acidities in order of decreasing acidic strength 3.36 0.82 2.54 18 3.02 0.68 2.34 41 2 98 0.70 2.28 64 3.03 0.63 2.40 Table 3. — Sample M, Naturally Oxidized Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash- free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen (Assuming one oxygen atom per equivalent) Nat. Oxid. Coal Mean 3.06 3.00 3.03 0.62 0.64 0.63 2.44 2.36 2.40 200 Mean 3.24 3.17 3.21 0.81 0.77 0.79 2.43 2.40 2.42 300 Mean 3.06 3.08 3.07 0.67 0.61 0.64 2.39 2.47 2.43 350 Mean 2.72 2.96 2.84 0.58 0.59 0.59 2.14 2.37 2.25 400 Mean 3.14 2.97 3.06 0.89 0.68 0.79 1.47 1.53 1.50 0.78 0.76 0.77 450 Mean 2.03 1.99 2.01 1.49 1.56 1.53 0.54 0.43 0.48 500 Mean 0.96 1.09 1.03 0.96 1.09 1.03 550 Mean 0.54 0.55 0.55 0.54 0.55 0.55 600 Mean 0.38 0.35 0.37 0.38 0.35 0.37 11.38 10.85 10.35 8.35 7.21 4.85 42.6 1.37 5.14 45.2 11.22 4.91 43. 4.54 41 4.90 47.3 3.22 38.6 .65 22.9 5.37 0. 16.4 3.51 0.59 16 TABULAR DATA 59 Table 4. — Sample M, Variation of Acidity During Forced Oxidation. Values in milliequivalents per gram of dry, ash-free coal. Time exposed (days) Total acidity Component acidities in order of decreasing acidic strength 3.36 0.82 2.54 9 3.50 1.49 2.01 34 4.12 1.78 2.34 47 4.15 0.69 1.37 2.09 Table 5. — Sample M, Forced Oxidized Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen Based on assumption stated in text, p. 21 Forced Oxid. Coal Mean 4.15 4.15 4.15 200 Mean 3.82 3.91 3.87 300 Mean 4.21 4.15 4.18 350 Mean 3.83 3.94 3.89 400 Mean 5.29 5.24 5.27 450 Mean 3.62 3.45 3.54 500 Mean 0.65 0.71 0.68 550 Mean 0.30 0.33 0.32 600 Mean 0.36 0.36 0.36 0.62 0.76 0.69 0.52 0.51 0.52 0.60 0.60 0.60 1.53 1.48 1.51 1.56 1.61 1.59 1.39 1.34 1.37 1.41 1.50 1.45 1.01 1.13 1.07 1.84 1.79 1.82 0.65 0.71 0.68 0.30 0.33 0.32 0.36 0.36 0.36 2.14 2.05 2.09 1.89 1.90 1.90 1.37 1.31 1.34 0.95 1.17 1.06 1.62 1.63 1.63 1.23 1.11 1.17 1.35 1.29 1.32 2.11 2.00 2.05 1.78 1.66 1.72 20.29 8.83 43.5 19.78 8.51 10.33 8.16 1.09 6.02 0.51 43.0 17.12 8.40 49.1 15.22 7.72(?) 50. 7(?) 13.26 10.02(?) 75. 6(?) 5.6.6 54.: 13.4 8.5 4.83 0.58 12.0 60 ILLINOIS STATE GEOLOGICAL SURVEY Table 6. — Sample N, Fresh Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen (Assuming one oxygen atom per equivalent) Fresh Coal Mean 0.64 0.66 0.65 3.15 3.11 3.13 10.36 6.05 58.4 200 Mean 300 Mean 350 Mean 400 Mean 450 Mean 500 Mean 550 Mean 600 Mean 5.61 5.58 5.60 4.91 5.00 4.96 4.39 4.45 4.42 2.42 2.66 2.77 2.62 2.36 1.92 2.59 2.29 0.58 0.57 0.44 0.53 0.35 0.55 0.41 0.44 0.66 0.72 0.69 0.78 0.81 0.80 0.78 0.64 0.71 0.58 0.67 0.63 1.19 1.23 1.23 1 22 0.94 0.95 0.85 0.91 0.58 0.57 0.44 0.53 0.35 0.55 0.41 0.44 3.03 2.98 3.01 2.84 2.84 2.84 2.40 2.58 2.49 2.01 1.96 1.93 0.63 0.91 0.95 0.83 1.99 1.93 1.96 1.73 1.78 1.76 0.71 1.09 0.58 1.24 0.65 1.16 0.60 0.52 0.59 0.57 1.42 0.97 1.74 1.38 10.92 11.59 10.90 10.11 8.51 6.21 4.74 4.56 5.92 8.96 7.94 7.07 4.19 3.66 0.85 0.70 54.2 77.3 72.8 69.9 49.2 58 9 17.9 15.4 TABULAR DATA 61 Table 7. — Sample N, Variation of Acidity During Natural Oxidation. Values in milliequivalents per gram of dry, ash-free coal. Time exposed (days) Total acidity Component acidities in order of decreasing acidic strength 3.78 0.65 3.13 26 3.22 0.56 2.66 44 3.51 0.87 2.64 64 3.68 0.82 2.86 Table 8. — Sample N, Naturally Oxidized Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen (Assuming one oxygen atom per equivalent) Nat. Oxid. Coal Mean 3.66 3 70 3.68 200 Mean 3 62 3 62 3 62 300 Mean 3 47 3.47 3 47 350 Mean 3 61 3 65 3 63 400 Mean 3 14 3 20 3 17 450 Mean 2 38 2 42 2 40 500 Mean 77 80 79 550 Mean 29 30 30 600 Mean 37 32 35 83 81 82 83 82 83 91 84 88 82 82 82 83 71 0.77 1.19 1 23 1 21 77 80 79 29 30 30 37 32 0.35 2.83 2.89 2.86 2 79 2 80 2.79 2.17 1 34 1 45 1.40 0.74 54 64 0.97 1 04 1 00 10.88 10.62 10.56 8.62 7.75 5.89 54.1 5.79 54.5 5.55 52.6 10.05 5.81 5 99 1.26 4.18 0.48 57.8 5.07 58. 3.84 49.5 21 11.5 3.69 56 15 2 62 ILLINOIS STATE GEOLOGICAL SURVEY Table 9. — Sample N, Variation of Acidity During Forced Oxidation. Values in milliequivalents per gram of dry, ash-free coal. Time exposed (days) Total acidity Component acidities in order of decreasing acidic strength 3.78 0.65 3.13 17 4.43 1.58 2.85 35 5.05 1.62 3.43 47* 5.37 2.08 3.29 *Ten ml of benzene used to facilitate titration. Table 10. — Sample N, Forced Oxidized Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carh. temp. Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen Based on assumption stated in text, p. 32 Forced Oxid. Coal* Mean 5.37 5.37 5.37 2.06 2.09 2.08 3.31 3.28 3.29 200 Mean 5.01 5.16 5.19 5.12 2.34 2.13 1.99 2.15 2.67 3.03 3.20 2.97 300 Mean 4.34 4.36 4.35 1.66 2.03 1.85 2.68 2.33 2.50 350 Mean 3.78 3.80 3.79 1.31 1.46 1.39 1.91 1.88 1.90 0.56 0.46 0.50 400 Mean 2.69 2.61 2.65 0.95 0.96 0.96 1.74 1.65 1.69 450 Mean 1.43 1.43 1.43 0.96 0.98 0.97 0.47 0.45 0.46 500 Mean 0.39 0.34 0.37 0.39 0.34 0.37 550 Mean 0.38 0.27 0.33 0.38 0.27 0.33 600 Mean 0.29 0.24 0.27 0.29 0.24 0.27 20.43 10.61 51.9 19.61 10.30 52.5 16.85 8.51 15.18 10.14 7.81 0.59 6.25 0.53 4.19 0.43 50.5 6.97 45.9 12.42 4.54 36.6 2.29 22.6 7.6 8.5 10.3 *10 ml benzene used in titration to avoid stickiness. TABULAR DATA 63 Table 11. — Sample O, Fresh Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen (Assuming one oxygen atom per equivalent) Fresh Coal Mean 2.61 2.52 2.50 2.54 0.60 0.60 0.59 60 200 Mean 2.62 2.62 2.62 0.60 0.64 0.62 300 Mean 2.47 2 50 2 49 0.50 51 51 350 Mean 2 25 2 30 2 28 0.55 0.68 0.62 400 Mean 2 32 2.53 2.35 2.60 2 45 0.86 0.88 60 76 0.78 49 69 0.50 450 Mean 1 39 1.68 1.51 1.53 0.70 68 82 0.73 500 Mean 36 37 37 0.36 37 37 550 Mean 0.33 31 0.32 33 31 0.32 600 Mean 0.59 0.31 0.45 59 31 0.45 2.01 1.92 1.91 1.94 2.02 1.98 2.00 1.97 1.99 1.98 1.70 1.62 1.66 0.97 0.96 0.46 0.79 0.77 1.67 0.69 1.00 0.69 0.80 7.52 8.04 8.02 7.91 6.97 5.96 5.13 3.52 2.85 4.06 4.19 3.98 3.65 3.92 2.45 0.59 0.51 0.72 54.0 52. 49.6 46. 56.2 41.1 11.5 14.5 25.3 64 ILLINOIS STATE GEOLOGICAL SURVEY Table 12. — Sample O, Variation of Acidity During Natural Oxidation. Values in milliequivalents per gram of dry, ash- free coal. Time Component acidities in exposed Total acidity order of decreasing (days) acidic strength 2.54 60 1 94 12 2 08 46 1 62 21 1 82 55 1 27 30 2 03 66 1 37 37 1 83 57 1 26 48 2 09 41 99 0.69 64 2 62 68 1 94 Table 13. — Sample O, Naturally Oxidized Coal Carbonization Series. Aridities in milliequivalents per gram. All values based on dry, ash free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coa) Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen (Assuming one oxygen atom per equivalent) Nat. Oxid. Coa] Mean 2.67 2 56 2 62 0.67 0.68 0.68 2 00 1 88 1 94 200 Mean 2 71 2 70 2.71 80 71 0.76 1 91 1 99 1 95 300 Mean 2 68 2 58 2 63 79 65 0.72 1 89 1 93 1 91 350 Mean 2 22 2 24 2 37 2 38 2 30 75 66 52 0.60 63 1 47 1 58 1 85 1 78 1 67 400 Mean 2 53 2 56 2 82 2 75 2.67 60 53 54 61 57 99 94 1 11 28 1 30 98 1 30 84 1.18 92 450 Mean 1 64 1 64 1 64 84 92 88 80 72 0.76 500 Mean 57 58 0.58 57 58 58 550 Mean 40 37 39 40 37 39 600 Mean 44 48 46 44 48 46 64 7 61 8.13 8 40 7 91 7 40 5 73 4 87 3 93 3 37 4.19 4.34 4.21 3.68 4 27 2.62 93 62 74 55 1 53.4 50. 46 5 57.7 45 7 19 15 8 22 TABULAR DATA 65 Table 14. — Sample O, Variation of Acidity During Forced Oxidation. Values in milliequivalents per gram of dry, ash- free coal. Time exposed (days) Total acidity Component acidities in order of decreasing acidic strength 2 54 60 1 94 14 3 89 1 38 2 51 27 4 32 1 80 2 52 36 4 39 1 85 2 54 47 4 47 2 02 2 45 Table 15. — Sample O, Forced Oxidized Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen Based on assumption stated in text, p. 41 Forced Oxid. Coal Mean 4 39 4 55 4 38 4 54 4 47 200 Mean 4 11 4 19 4 29 4 20 300 Mean 4 00 4 03 4 02 350 Mean 5 11 5 06 5 09 400 Mean 2.47 2 66 2.63 2 59 450 Mean 2 03 2 03 2 03 500 Mean 35 40 38 550 Mean 27 28 28 600 Mean 28 27 28 2 01 2 07 1 79 2 20 2 02 0.72 0.95 1.34 2.38 2.45 1.76 1.64 1.00 2 01 2 10 2 16 2 09 1 06 97 2.10 2.11 1.03 1.16 1 34 1 27 1 30 1 93 2 02 1 98 73 74 74 1.28 1 22 1 25 1 65 1 59 1,62 2 18 2 25 2 22 1 00 97 97 98 1 06 1 17 1.19 1.14 41 52 52 48 84 84 84 35 40 38 0.27 28 28 28 27 28 1.19 1 19 1.19 18.28 20.99 14.85 13.08 10.67 9 05 6.54 4.80 3.45 9 30 85 7.36 9.14 4.82 3 25 0.61 45 0.45 50.9 42 2 49.6 69.9 45.2 35 9 9.3 9.4 13 66 ILLINOIS STATE GEOLOGICAL SURVEY Table 16. — Sample P, Fresh Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen (Assuming one oxygen atom per equivalent) Fresh Coal Mean 0.85 0.81 0.83 0.14 0.15 0.15 200 0.81 0.30 300 0.79 0.26 350 Mean 0.40 0.44 0.42 400 Mean 0.48 33 0.41 0.41 450 Mean 0.41 0.63 0.55 500 Mean 0.78 0.69 0.74 0.25 0.25 0.25 550 0.35 600 0.32 0.71 0.66 0.68 2.45 1.33 54.3 0.51 2.41 1.30 53.9 0.53 2.50 1.26 50.4 0.40 0.44 0.42 2.26 0.67 29.6 0.48 0.33 0.41 0.41 2.50 0.66 26.4 0.41 0.63 0.55 2.45 0.88 35.9 0.53 0.44 0.49 2.70 1.18 43.7 0.35 2.27 0.56 24.7 0.32 2.61 0.51 19.5 TABULAR DATA 67 Table 17. — Sample P, Naturally Oxidized Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen (Assuming one oxygen atom per equivalent) Nat. Oxid. Coal Mean 0.64 0.60 0.62 02 0.16 0.09 0.62 0.44 0.53 200 Mean 69 0.87 78 04 04 04 0.43 0.65 0.74 300 Mean 0.46 0.46 0.46 01 0.01 01 0.45 0.45 0.45 350 Mean 40 40 40 40 40 40 400 Mean 42 44 0.43 42 44 43 450 Mean 48 45 0.47 48 45 47 500 Mean 43 52 48 43 52 48 550 Mean 30 25 28 30 25 28 600 32 32 0.40 2.10 2.09 0.99 47.1 25 59.1 2.27 0.74 2.05 0.64 2.26 0.69 2.19 0.75 2 33 0.77 2.81 0.45 2 61 51 32.6 31.2 30.5 34.2 33.0 16.0 19.5 Table 18. — Sample P, Variation of Acidity During Forced Oxidation. Values in milliequivalents per gram of dry, ash -free coal. Time exposed (days) Total acidity Component acidities in order of decreasing acidic strength 83 0.15 0.68 37 1 19 34 85 47 1 58 55 0.52 0.51 68 ILLINOIS STATE GEOLOGICAL SURVEY Table 19. — Sample P, Forced Oxidized Coal Carbonization Series. Acidities in milliequivalents per gram. All values based on dry, ash-free coal. Carb. temp. °C Total acidity Component acidities in order of decreasing acidic strength Percent of coal Total oxygen (by diff.) Acidic oxygen Acidic oxygen as % of total oxygen Based on assumption stated in text, p. 51 Forced Oxid. Coal Mean 1.59 1.49 1.66 1.58 200 Mean 1.43 1.30 1.56 1.43 300 Mean 1 32 1 13 1 24 1 23 350 Mean 1 06 1 07 1 12 1 08 400 Mean 0.80 80 84 85 82 450 Mean 0.65 65 75 0.68 500 Mean 0.49 0.48 43 0.47 550 Mean 0.34 0.40 0.37 600 Mean 32 29 0.31 0.54 0.55 0.56 0.55 0.54 0.51 0.57 0.54 49 46 46 47 0.32 45 37 38 0.40 0.34 33 0.32 0.35 0.65 0.65 0.75 0.68 0.49 0.48 0.43 0.47 0.34 0.40 0.37 0.32 0.29 0.31 0.53 0.51 0.52 05 0.89 0.79 99 0.89 0.83 0.67 78 0.76 0.74 0.62 0.75 70 0.40 0.46 0.51 0.53 0.47 0.41 0.59 0.51 5.92 5.70 4.77 4.32 4.02 3 05 2.13 2.08 2 97 2.53 2.29 1.97 1.73 1.31 .09 0.75 0.59 50 42.7 40.2 41.3 40.0 32.6 35.7 35.2 28.4 16.8 TABULAR DATA 69 Table 20. — Fresh Sample M, Analytical Data for Coal and Carbonized Products. Percent Moisture (as received) 14.3 Vol. matter (d.a.f.) 49.4 Forms of sulfur (d.a.f.) : Sulfate 0.56 Pyritic 0.48 Organic 2.17 Total 3.21 Petrographic analysis: Vitrinite 95.5 Exinite 2.6 Inertinite 1.1 Mineral matter 0.8 Calorific value (d.a.f.): Btu/lb 14382 cal/g 7989 Gieseler plasticity: Softening temp 353°C Fusion temp . 391 °C Max. fluidity temp 415°C Setting temp 469°C Maximum Fluidity, dial div./min. . 2320* Free swelling index 3£ Carb. temp., °C Ash (dry) Dry, ash-free basis C H N S O** Wt. t Carbonization product Fresh coal 2.46 79.60 5.53 1.44 3.25 10.18 16.72 200 2 80 78.99 5.51 1.43 3.32 10.75 16.55 300 2.55 79.23 5.48 1.45 3.29 10.55 16 46 350 2.60 80.57 5.40 1.46 3.08 9.49 15.78 400 2.93 82.58 4.66 1.59 2.72 8.45 13.82 450 3.31 84.67 3.97 1.68 2.57 7.11 12.11 500 3.54 86.51 3.40 1.70 2.25 6.14 11.48 550 4.95 87 36 3.05 1.71 2.19 5.69 11.30 600 4.69 89.08 2.65 1.70 2 21 4.36 10.99 Unconsolidated char Unconsolidated char Slightly consolidated char; broke up on hand- ling Verv highly swollen coke; frothy texture, soft Highly swollen coke; frothy texture, soft Slightly swollen coke; moderately hard Unswollen hard coke Slightly shrunken hard coke *Packed with 3 drops of benzene; swelled out of sample cup. ^Oxygen percentage obtained by difference. fGrams obtained from 20 grams of coal charged to the retort. 70 ILLINOIS STATE GEOLOGICAL SURVEY Table 21. — Naturally Oxidized Sample M, Analytical Data for Coal and Carbonized Products. Moisture (as received) Vol. matter (d.a.f.) . Percent 2.7 45.1 Calorific value (d.a.f.): Btu/lb 14299 cal/g 7944 Free swelling index 4 Gieseler plasticity: Softening temp . . 353°C Fusion temp 417°C Max. fluidity temp 427°C Setting temp 454°C Maximum fluidity, dial div./min. Carb. temp., °C Ash (dry) Dry, ash- free basis C H N S o** Wt. t Carbonization product Coal 2.42 78.51 5.37 1.43 3.31 11.38 18.99 200 2.69 78.45 5.32 1.46 3.40 11.37 18.74 300 2.60 78.74 5.27 1.47 3.30 11.22 18.56 350 - 2.70 79.46 5.09 1.48 3.12 10.85 17.89 400 3.05 81.02 4.20 1.66 2.77 10.35 15.43 450 3 40 83.53 3.75 1.62 2.75 8.35 14.05 500 3.52 85.38 3.31 1.64 2.46 7.21 13.29 550 4.03 87.53 2.99 1.75 2.36 5.37 12.79 600 4.43 89.71 2.69 1.75 2.34 3.51 12.38 Unconsolidated char Unconsolidated char Soft consolidated char Soft unswollen coke Moderately hard unswollen coke Moderately hard slightly shrunken coke Hard slightly shrunken coke Hard slightly shrunken coke *Packed with 6 drops of benzene. **Oxygen percentage obtained by difference. fGrams obtained from 20 grams of coal charged to the retort. Table 22. — Forced Oxidized Sample M, Analytical Data for Coal and Carbonized Products Percent Moisture (as received) Vol. matter (d.a.f.) . Free swelling index 2.1 39.1 Calorific value (d.a.f.): Btu/lb . . . cal/g .... Gieseler plasticity: Unobtainable; coal non-agglomerating 11931 6628 Carb. Ash (dry) Dry, ash-free basis Carbonization product temp., °C C H N S O** Wt. t Coal 2.2 71.24 4.10 1.30 3.07 20.29 19.14 200 2.3 71.73 4.08 1.35 3 06 19 78 18.78 Unconsolidated char 300 2.4 74.39 4.11 1.41 2.97 17.12 17.61 Unconsolidated char 350 2.7 76.44 4.02 1.44 2.88 15.22 16.70 Very slightly coherent char, crumbled on handling 400 2.7 78.79 3.78 1.55 2.62 13.26 15.67 Very slightly coherent char, crumbled on handling 450 2.8 81.98 3.53 1.64 2.52 10.33 14.72 Very slightly coherent char, crumbled on handling 500 3.3 84.46 3.29 1.70 2.39 8.16 13.92 Very slightly coherent char, crumbled on handling 550 3.8 86.95 2.91 1.71 2.41 6.02 13.22 Slightly coherent char, easily crushed 600 4.5 88.40 2.66 1.69 2.42 4.83 12.71 Slightly coherent char, easily crushed ^Oxygen percentage obtained by difference. fGrams obtained from 20 grams of coal charged to the retort. TABULAR DATA 71 Table 23. — Fresh Sample N, Analytical Data for Coal and Carbonized Products. Percent Moisture (as received) 8.0 Vol. matter (d.a.f.) 38.4 Forms of sulfur (d.a.f.) : Sulfate 0.02 Pyritic 36 Organic 0.53 Total 0.91 Petrographic analysis: Vitrinite 91.6 Exinite 4.6 Tnertinite 2.8 Mineral matter 1.0 Calorific value (d.a.f.) : Btu/lb 14452 cal/g 8029 Gieseler plasticity: Softening temp 383°C Fusion temp 407°C Max. fluidity temp 424°C Setting temp 456°C Maximum fluidity, dial div./min. . 27 Free swelling index 4 Carb. Ash (dry) Dry, ash-free basis temp., °C C H N S o** Wt.f Carbonization product Coal 9.7 81.59 5.19 1.90 96 10 36 20.77 200 9 9 81.10 5.22 1.84 92 10.92 20.66 300 10 80.55 5.10 1.81 95 11.59 20.41 350 10 1 81.35 5.02 1.82 91 10.90 19.99 400 11 1 82 71 4.40 1.96 0.82 10 11 17.90 450 12 1 84.72 3.89 2.07 0.81 8 51 16.28 500 13 87 47 3 46 2.15 0.71 6.21 15.35 550 15 .0 89 42 3.02 2.12 0.70 4.74 14.53 600 15.6 89.80 2 84 2.05 0.75 4.56 14.15 Unconsolidated char Unconsolidated char Slightly consolidated char, broke up on hand- ling Soft unswollen coke Moderately hard slightly shrunken coke Hard slightly shrunken coke Hard slightly shrunken coke Hard slightly shrunken coke **Oxygen percentage obtained by difference. fGrams obtained from 25 grams of coal charged to the retort. Table 24. — Naturally Oxidized Sample N, Analytical Data for Coal and Carbonized Products. Percent Moisture (as received) 2.6 Gieseler plasticity: Vol. matter (d.a.f.) 37.5 Calorific value (d.a.f.) : Btu/lb 14367 cal/g 7982 Free swelling index 4 Softening temp 397°C Fusion temp. — Max. fluidity temp 413°C Setting temp 453°C Maximum fluidity, dial div./min. . . 2 Carb. temp., °C Ash (dry) Dry, ash-free basis C H N S 0** Wt.f Carbonization product Coal 9 8 80 96 5.25 1.84 1.07 10.88 21.97 200 9.9 81 23 5.26 1.89 1 00 10.62 21.84 300 10.0 81 35 5.27 1.79 1.03 10.56 21 72 350 10 82 08 5 .19 1.74 0.94 10 05 21.16 400 11.0 84.13 4.54 1.88 0.83 8.62 18.89 450 12.0 85 45 3.93 2.03 0.84 7 75 17.37 500 12.8 88.33 3.56 2.06 0.71 5 34 16 42 550 13.9 90.57 3.11 2.11 0.67 3 54 15 63 600 14.8 90.97 2.73 2.12 0.70 3 48 15 15 Unconsolidated char Unconsolidated char Very slightly consolidated char, broke up on handling Soft unswollen coke Moderately hard unswollen coke Moderately hard slightly shrunken coke Moderately hard slightly shrunken coke Moderately hard slightly shrunken coke **Oxygen percentage obtained by difference. tGrams obtained from 25 grams of coal charged to the retort. 72 ILLINOIS STATE GEOLOGICAL SURVEY Table 25. — Forced Oxidized Sample N, Analytical Data for Coal and Carbonized Products. Percent Moisture (as received) 2.7 Calorific value (d.a.f.) : Vol. matter (d.a.f.) . Free swelling index 2.7 36.3 Btu/lb 11924 cal/g 6624 Gieseler plasticity: Unobtainable; coal nonagglomerating Carb. Ash (dry) Dry, ash-free basis Carbonization product temp., °C C H N S o** Wt.f Coal 9 1 73 03 3 89 1.74 91 20 43 22 09 200 9.3 73 80 3.89 1.72 0.98 19 61 21 66 Unconsolidated char 300 9 8 76.43 3.92 1.86 0.94 16.85 20 27 Unconsolidated char 350 10.1 78.19 3.80 1.90 93 15 18 19.34 Unconsolidated char 400 10.7 80.94 3.69 2 00 95 12 42 18 42 Unconsolidated char 450 11.2 83 28 3.50 2.12 0.96 10 14 17 35 Unconsolidated char 500 11.7 85.99 3.19 2 15 86 7 81 16 69 Unconsolidated char 550 13.1 87 65 3 09 2 20 81 6 25 15 71 Unconsolidated char 600 11.6 90 21 2 65 2.17 78 4 19 15.61 Unconsolidated char *Oxygen percentage obtained by difference. fGrams obtained from 25 grams of coal charged to the retort. Table 26. — Fresh Sample O, Analytical Data for Coal and Carbonized Products. Moisture (as received) Vol. matter (d.a.f.) . Forms of sulfur (d.a.f.) Sulfate Pyritic. Organic Total . . . Petrographic analysis: Vitrinite . Exinite. Inertinite . Mineral matter . Percent 2.4 42.5 0.00 33 1.84 2.17 80.5 5.4 10.2 3.9 Calorific value (d.a.f.) : Btu/lb 15053 cal/g 8363 Gieseler plasticity: Softening temp 366°C Fusion temp 390°C Max. fluidity temp 445°C Setting temp 476°C Maximum fluidity, dial div./min. . — * Free swelling index 7 Carb. temp., °C Ash (dry) Dry, ash-free basis N O* Wt.f Carbonization product Coal 200 300 350 400 450 500 550 600 4 7 83.17 5.55 1 58 2 18 7 52 23 28 4.6 4 7 4.8 5.4 6.5 7.6 82.74 82 79 82.97 85 10 86 60 87.89 5.53 5.47 5 35 4.54 3.79 3 31 2 03 2 12 8 04 8 02 7.91 6 97 5 96 5.13 23.27 22.81 22 47 18.88 16 60 15.66 Unconsolidated char Unconsolidated char Slightly consolidated char Highly swollen frothy coke Very highlv swollen frothy coke Very highly swollen frothy coke 9 5 89.81 3 05 2 01 1.61 3.52 15.52 Very highlv swollen frothy coke LI 6 90.94 2.56 2 05 1.60 2.85 14.94 Very highly swollen frothy coke *Most of coal swelled out of cup and into barrel. h *Oxygen percentage obtained by difference. tGrams obtained from 25 grams of coal charged to the retort. TABULAR DATA Table 27. — Naturally Oxidized Sample O, Analytical Data for Coal and Carbonized Products. Moisture (as received) Vol. matter (d.a.f.) . Percent 1.2 42.5 Calorific value (d.a.f.): Btu/lb 14761 cal/g 8200 Free swelling index 8 Gieseler plasticity : Softening temp 375°C Fusion temp 398°C Max. fluidity temp 440°C Setting temp 478°C Maximum fluidity, dial div./min. . . — * Carb. temp., °C Ash (dry) Dry, ash-free basis H N O" Wt.f Carbonization product Coal 4.6 83.01 5.56 1.67 2.15 7.61 23.60 200 4.6 82.53 5.49 1.69 2.16 8.13 23.19 300 4.7 82.36 5.39 1.70 2.15 8.40 23.13 350 4.7 82.95 5.31 1.70 2.13 7.91 22.76 400 5.3 84.28 4.67 1.88 1.77 7.40 19.98 450 6.1 86.66 3.93 2.00 1.68 5.73 16.95 500 7.1 88.10 3.42 2 06 1.55 4.87 15.70 550 9.8 89.42 2.98 2.05 1.62 3.93 15.28 600 11.3 90.46 2.60 2.01 1.56 3.37 14.95 Unconsolidated char Unconsolidated char Slightly consolidated char Highlv swollen frothy coke Very highly swollen frothy coke Very highly swollen frothy coke Very highly swollen frothy coke Very highly swollen frothy coke *Most of coal swelled out of cup and into barrel. *Oxygen percentage obtained by difference. f Grams obtained from 25 grams of coal charged to the retort. Table 28. — Forced Oxidized Sample O, Analytical Data for Coal and Carbonized Products. Percent Moisture (as received) 5 Free swelling index Vol. matter (d.a.f.) 35.7 Calorific value (d.a.f.): Gieseler plasticity: Btu/lb 12312 Unobtainable; coal nonagglomerating cal/g '.'.'.'.'.'.... 6841 Carb. Ash (dry) Dry, ash- free basis Carbonization product temp., °C C H N S o** Wt.f Coal 4.4 74 20 4 09 1.45 1.98 18 28 23.85 200 4.4 71.33 4.03 1.64 2.01 20.99 23.31 Unconsolidated char 300 4.7 77.40 4.14 1.66 1.95 14.85 21.97 Unconsolidated char 350 4.8 79.14 4 24 1.63 1.91 13 08 21.10 Unconsolidated char 400 5.2 81.78 4 03 1.68 1.84 10.67 19.64 Unconsolidated char 450 5.5 84 01 3.50 1,66 1.78 9.05 18.78 Unconsolidated char 500 6.4 86 87 3.18 1.69 1.72 6.54 17.66 Unconsolidated char 550 7.1 88 85 2 90 1.71 1,74 4.80 17.02 Unconsolidated char 600 7.8 90.58 2.51 1.72 1.74 3.45 16.32 Unconsolidated char ^Oxygen percentage obtained by difference. i'Grams. obtained from 25 grams of coal charged to the retort. 74 ILLINOIS STATE GEOLOGICAL SURVEY Table 29. — Fresh Sample P, Analytical Data for Coal and Carbonized Products. Moisture (as received) Vol. matter (d.a.f.) . Forms of sulfur (d.a.f.) Sulfate. . . . Pyritic. Organic Total Petrographic analysis: Vitrinite Exinite. Inertinite . Mineral matter Percent 0.5 18.9 0.00 0.03 0.53 0.56 85.6 0.0 13.4 1.0 Calorific value (d.a.f.) : Btu/lb 15647 cal/g 8693 Gieseler plasticity: Softening temp 435°C Fusion temp 459°C Max. fluidity temp 475°C Setting temp 484°C Maximum fluidity, dial div./min. . 85* Free swelling index 9 Carb. temp., °C Ash (dry) Dry, ash- free basis H N O* Wt.f Carbonization product Coal 2 4 91.23 4 48 1.28 0.56 2 45 24.28 200 2 6 91 36 4.48 1 16 0.59 2 41 24.08 300 2 6 91.25 4.43 1.26 0.56 2.50 24.11 350 2 6 91.50 4.46 1.21 0.57 2.26 24.10 400 2 6 91.44 4 40 1 08 0.58 2.50 23.93 450 2 7 91 52 4 10 1.33 0.60 2.45 22.09 500 3 1 91 94 3 46 1.26 0.64 2.70 21.50 550 3 2 92 61 3.14 1 38 0.60 2.27 21.44 600 3 6 92 68 2.78 1.33 0.60 2.61 21.03 Unconsolidated char Unconsolidated char Very slightly coherent char, easily crushed Slightly coherent char broke up on handling Moderately hard highly swollen coke Moderately hard highly swollen coke Moderately hard highly swollen coke Moderately hard highly swollen coke *Some of coal swelled into barrel. **Oxygen percentage obtained by difference. fGrams obtained from 25 grams of coal charged to the retort. Table 30. — Naturally Oxidized Sample P, Analytical Data for Coal and Carbonized Products. Percent Moisture (as received) 0.5 Vol. matter (d.a.f.) 19.5 Calorific value (d.a.f.) : Btu/lb 15619 cal/g 8678 Free swelling index 9 Gieseler plasticity: Softening temp 435°C Fusion temp. . . 455°C Max. fluidity temp 477°C Setting temp 504°C Maximum fluidity, dial div./min. 22 Carb. Ash (dry) Dry, ash- free basis Carbonization product temp., °C C H N S o** Wt.f Coal 2.5 91.41 4.58 1.33 0.58 2.10 24.28 200 2.5 91.39 4.56 1.39 0.57 2.09 24.05 300 2.6 91.38 4.53 1.24 0.58 2.27 23 94 350 2.8 91.57 4.52 1.27 0.59 2.05 23.79 400 2.8 91 55 4.50 1 12 0.57 2 26 23.74 450 2.9 91.94 4.24 1.06 0.57 2 19 23.06 500 3.2 92.40 3.59 1.10 0.58 2.33 21.76 550 2.8 92.28 3.25 1.09 57 2.81 21.36 600 3 2 92 74 2.98 1.08 59 2.61 21 18 Unconsolidated char Unconsolidated char Unconsolidated char Slightly consolidated char broke up on hand- ling Moderately hard swollen coke Moderately hard highly swollen coke Moderately hard highly swollen coke Moderately hard highly swollen coke **Oxygen percentage obtained by difference. fGrams obtained from 25 grams of coal charged to the retort. TABULAR DATA 75 Table 31. — Forced Oxidized Sample P, Analytical Data for Coal and Carbonized Products. Percent Moisture (as received) 0.7 Free swelling index ....... Vol. matter (d.a.f.) 19.0 Calorific value (d.a.f.): Gieseler plasticity: Btu/lb 14933 Unobtainable, coal non agglomerating cal/g 8296 Carb. Ash (dry) Dry, ash-free basis Carbonization product temp., °C C H N S o** Wt.f Coal 2.6 88 00 4.23 1 23 0.62 5.92 24 23 200 2.5 88.19 4.21 1 31 0.59 5.70 24.08 300 2.7 89.52 4.11 1 04 0.56 4.77 23.65 350 2.8 90 00 4.12 1 01 0.55 4 32 23.43 400 2.6 90.15 4 03 1 20 0.60 4.02 23.10 450 2.9 91.26 3.87 1 23 0.59 3 05 22.47 500 2.9 92 43 3.56 1 29 0.59 2.13 21 89 550 3 2 92.71 3 24 1 37 0.60 2 08 21 21 600 4.5 92.46 2.89 1 14 0.54 2.97 20.49 Unconsolidated char Unconsolidated char Unconsolidated char Unconsolidated char Unconsolidated char Unconsolidated char Unconsolidated char Unconsolidated char **Oxygen percentage obtained by difference. fGrams obtained from 25 grams of coal charged to the retort. Table 32. — Fresh Sample Q, Analytical Data. Moisture (as received) Ash (dry) .... Vol. matter (d.a.f.) . Forms of sulfur (d.a.f.) : Sulfate. . . . Pyritic. Organic Total . . . Percent 4 6 11 5 37.3 0.15 2 52 63 3 30 Calorific value: Btu/lb 15201 cal/g 8445 Gieseler plasticity: Softening temp. . Fusion temp. . Max. fluidity temp. Setting temp. Maximum fluidity, dial div./min. 393°C 414°C 443°C 477°C 2000 Free swelling index 6| Dry, ash-free basis C H N S O** 85.10 5.36 1.51 3.44 4.59 ^Oxygen percentage obtained by difference. Illinois State Geological Survey Report of Investigations 212 75 p., 31 figs., 32 tables, 1959