s 14. GS: cir aa7 c 3 Gqfco\ Slx^ajeaj STATE OF ILLINOIS WILLIAM G. STRATTON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION VERA M. BINKS, Director WEATHERING OF ILLINOIS COALS DURING STORAGE H. W. Jackman, R. L. Eissler, and F. H. Reed DIVISION OF THE ILLINOIS STATE GEOLOGICAL SURVEY JOHN C. FRYE, Chief URBANA CIRCULAR 227 1957 WEATHERING OF ILLINOIS COALS DURING STORAGE H. W. Jackman, R. L. Eissler, and F. H. Reed ABSTRACT No. 5 and No. 6 coals from southern Illinois, in the sizes sup- plied commercially for metallurgical coke, may be stocked out of doors for six months during the winter period without appreciable change in their coking properties. These same coals maybe stock- ed for 30 days in warm summer weather, but longer summer stor- age may cause undesirable changes in coke structure. No. 6 coal weathers more rapidly than No. 5. INTRODUCTION Since 1944-; southern Illinois coals have been used continuously in blends with coals from the East for production of metallurgical coke. Extended stor- age of these coals, especially of the smaller sizes, is known to result in oxi- dation, or weathering, which renders the coals less strongly coking. As weath- ering is a reaction between the coal surfaces and oxygen from the air, there are two methods by which it may be reduced or prevented. Either (1) air should be prevented from entering storage piles, or (2) surface area should be kept at a minimum by storing only the larger sized pieces. Various methods developed for excluding air, such as packing coal fines tightly in storage piles with heavy bulldozers, are well known to the coal in- dustry and have enabled utility and industrial plants to stock large tonnages of coal fines for extended periods without loss. Both utility and metallurgical plants have demonstrated that either high- or low-rank coals may be stored under water for long periods without appreciable deterioration. Coal fines from the Illinois field should not be used for coke, partly be- cause of the tendency to weather and partly because a large proportion of the total fusain is found in the fine portion of the coal. The larger, double-screened sizes have a relatively small surface area as compared with the fines, and we have found that the portion of coal with a bottom size no smaller than 3/4-inch may be stocked safely for limited periods without packing. We have recommend- ed therefore that only the plus 3/4 -inch sizes of Illinois coals be used by the coke industry, and that these sizes be coked within 30 to 90 days after mining to a- void the possibility of oxidation. These recommendations have been followed by the industry and, with few exceptions, only the freshly-mined, double-screen- ed coals have been coked. PREVIOUS WEATHERING TESTS Although pilot plant tests had shown that both No. 5 and No. 6 coals could be stocked safely for 30 days, and in winter weather for much longer periods (Reed, 1947), we had no experience with stockpiling Illinois coals for commer- cial coke until the winter of 1945-46. In the fall of 1945 No. 6 coal, largely 6" x 3" and 3" x 2" from a number of mines, was stocked in a ridge-shaped pile approximately 150 feet long and 25 feet high on a concrete pad at a coke plant in the Chicago area. We sampled and tested this coal at intervals over a six- ILLINOIS STATE GEOLOGICAL SURVEY [ 1 ] 3 3051 00004 4853 ILLINOIS STATE GEOLOGICAL SURVEY 2 months period. The first two samples were taken from the top of the pile where the coal had been directly exposed to the weather. The six-month sample was taken from the center of the pile as coal was being removed from storage. Re- sults of the coking tests, shown in table 1, indicate that six-months storage had not caused sufficient weathering to be noticeable when this coal was used as 25 percent of the total coal blend. Coal in the pile still showed the original bright surfaces, and there was no size degradation or evidence of heating. The commercial-oven coke made with this coal from storage was normal in every respect. Table 1. - Illinois Coal Stocked in Plant Storage Pile During Winter Period Coal blend: 25% Illinois No. 6 25% Eastern Kentucky 50% Pocahontas No. 4 Tumbler Time in — storage, Shatter Stabili Run No. months +2" +1" 220 1 64.0 31.3 226 2 62.2 28.3 254 6 62.9 34.5 Average Breeze ardne ss size in 2 Apparent in. % of coal gravity 64.0 2.55 3.0 .887 62.7 2.63 3.1 .889 65.4 2.63 3.1 .892 Table 2. - Illinois Coal Stocked Under Water April 1 through February 1 Coal blend : 25% Illinois No. 6 34% Hernshaw 35% Pocahontas No. 3 6% Anthracite Time in storage, months Shatter +2" Tumbler Average size in. % Breeze in ~2 of coal Run No. Stabili +1" .ty Hardness .i_Lii Apparei gravit' 474-5 li 87.5 48.6 55.1 3.41 2.0 .910 481-2 4 87.3 48.4 55.9 3.45 2.1 .912 483-4 5* 87.3 51.9 58.5 3.40 2.0 .920 485-6 10 88.6 51.6 59.5 3.42 2.0 .928 Another series of weathering tests was made in 1950-51 on No. 6 coal stock- ed under water for ten months in a Midwest coke plant. Underwater storage very effectively prevented contact of coal with air and thus prevented oxidation, even though the coal was stored during the entire summer when temperatures at times reached 100° F. Table 2 shows results of tests, made at intervals throughout the period, in the pilot coke oven from blends containing 25 percent of this coal. Fresh eastern coals were used in each test along with the Illinois coal from storage, and the small increase in coke strength in the final tests 3 WEATHERING OF COALS DURING STORAGE may have been due either to slight weathering of the Illinois coal or to nonuni- formity of eastern coals. NEED FOR NEW WEATHERING TESTS In addition to the tests described above, other coals from a number of southern Illinois mines have been stocked at our laboratories and tested over a period of time. These studies have shown that weathering characteristics, although similar, are somewhat different for coals from the different seams, or from the same seam in different locations (Jackman, 1946). The last of these early tests was made in 1946, and the mines from which most of these coals were taken are now closed and replaced by newer mines, sometimes at a con- siderable distance from the older locations. It seemed desirable therefore to determine the weathering characteristics of coals from mines currently pro- ducing metallurgical coal, and to make this information available. METHODS OF TESTING It was known that the bituminous B rank coals mined in southern Illinois weather faster in hot weather than in cold. We decided, therefore, to make two series of tests, one covering the winter period from October through March, and the other the summer period from April through September. Coals mined by three southern Illinois producers were tested, one from the No. 5 seam and two from the No. 6. All these coals have been used for com- mercial production of metallurgical coke, and each was sampled in the size range actually supplied to the industry. All sizes fall within the range of 3" x 1". Approximately 2 1/2 tons of each Illinois coal were taken at the mines in such a way that all working faces were represented. These coals were stocked out-of-doors in conical piles about six feet in diameter. In such small piles the coals were subject to a maximum exposure to the weather. At intervals of about one month a sample of 500 pounds was taken from the outside of each pile, and blends of 75 percent Illinois coal and 25 percent Poca- hontas were tested in the Survey's movable-wall pilot coke oven (Jackman, 1955). These blends were carbonized in 16 1/2 hours under standard operating conditions so that the cokes produced were comparable with commercial oven coke. The Pocahontas slack used in all blends was stocked during the period of the tests in an outside covered bin partially open on one side to the atmos- phere. Fresh Pocahontas coal was obtained at the start of the second testing period so that no coal remained in stock longer than six months. The extent of weathering of the coals was judged by analytical determina- tions of Gieseler fluidity and free swelling index, by changes in the physical properties of cokes produced in the pilot oven, and by trends in expansion pres- sure. The physical properties affected primarily by weathering were the tum- bler indices and coke size, particularly the proportion of fines. Apparent grav- ity also tended to change as weathering progressed. We wish to thank each of the coal producers who furnished the Illinois coals used in the tests reported here. Also, we thank the Wisconsin Steel Company of Chicago for furnishing the Pocahontas coal used for blending. ILLINOIS STATE GEOLOGICAL SURVEY 4 RESULTS OF TESTS Winter Storage Tests on the three Illinois coals through the winter period paralleled our former experience with coals no longer mined, and indicated that very little weathering takes place during cold weather. Table 3 shows analyses and plas- tic properties of the coals being tested. Tables 4, 5, and 6 give pilot plant data for the six-month period, and figures 1 through 5 show certain of these data in graphical form from which the degree of weathering may be judged more easily. Table 3. - Coals Placed in Winter Storage Analyses and Plastic Properties Analyses Moisture-free basis Coal Illinois No. 5 Mined 9-27-55 Illinois No. 6A Mined 10-18-55 Illinois No. 6B Mined 10-3-55 Pocahontas Illinois No. 5 Illinois No. 6A Illinois No. 6B Pocahontas M. V.M. F.C. Ash Sulfur F.S.I. 7.0 37.5 54.9 7.6 1.69 7 8.6 39.0 53.2 7.8 1.77 5£ 8.6 37.7 54.5 7.8 1.02 5* 4.2 17.1 76.1 6.8 0.58 9 PI astic Properties Gieseler Fluid ity C Plast: Lc Range (°C) Dial div. per min. at ° Softening Solidification 116 436 385 464 14 427 388 459 10. 8 427 388 453 7 486 451 510 No. 5 coal is shown to be especially stable during winter storage, and show- ed no significant changes in the yield of coke breeze throughout the period. The tumbler stability gradually increased for about 100 days, then stayed above the value for fresh coal until the sixth -month test. The No. 6 coals likewise changed very little during this period. Breeze remained very constant for about four months, then increased slightly, especial- ly with the No. 6B coal blend. However, the increase in yield of breeze over that from the fresh coal never exceeded 1.0 percent. Tumbler stability showed a tendency to increase with the No. 6 coals after three to five months in storage. Otherwise, stability indices remained practical- ly constant throughout the entire period. Tumbler hardness tended to decrease only slightly on coke from the No. 6B coal, especially in the last two months. This coincided with the small increase in breeze. There were no significant changes in expansion pressures exerted by these blends over the winter period. Likewise, there was no well defined trend in coke gravity. Plasticity and swelling indices determined over the six months period, and shown in table A of the appendix, are fairly constant within the accuracy of WEATHERING OF COALS DURING STORAGE Table 4. - Coking Tests with Illinois No. 5 (Winter Period) Coal blend: 7b% Illinois No. 5 (Mined 9-27-55) 25% Pocahontas Run 154E Run 160E Run 167E Run 173E Run 181E Run 186E Run 194E Date of test Days since mining 111. coal 10-11-55 11-8-55 12-6-55 14 42 70 1-10-56 2-7-56 105 133 3-1-56 3-29-56 156 184 Coke physical properties Tumbler test Stability 57.1 57.0 57.8 59.8 58.3 58.1 56.4 Hardness 67.3 67.0 67.5 66.7 66.8 66.5 66.4 Shatter test +2" 78.8 81.8 81.9 75.6 82.1 83.9 79.2 + ii" 93.0 93.8 93.9 92.2 93.5 94.3 93.4 +1" 97.4 97.4 97.7 97.1 97.8 98.0 97.5 Coke sizing +4" 5.7 5.0 7.5 6.2 8.3 6.2 5.7 4" x 3" 20.1 16.6 28.6 28.0 32.2 24.6 22.8 3" x 2" 46.7 48.0 36.7 39.9 37.5 40.5 44.2 2" x 1" 21.5 24.5 22.1 19.4 16.4 22.3 20.7 1" x i" 1.6 1.7 1.4 2.1 1.4 2.3 2.3 4.7 4.2 3.7 4.4 4.2 4.1 4.3 Average size (in.) 2.47 2.40 2.61 2.57 2.71 2.51 2.50 Apparent gravity .827 .831 .834 .825 .839 .824 .828 Coke yie Ids (% of coal) (Coke at 3% M. - coal as received) Total 70.4 69.7 69.8 70.6 70.3 69.7 69.4 Furnace (+1") 66.2 65.6 66.2 66.0 66.4 65.3 64.8 Nut (1" x i") 1.1 1.2 1.0 1.5 1.0 1.6 1.6 Breeze (-J-") 3.1 2.9 2.6 3.1 2.9 2.8 3.0 Expans ion pressure Lbs. per sq. in. 1.37 1.32 1.28 1.-35 1.20 1.28 1.17 Bulk density (Lbs. per cu.ft. ) 51.1 50.7 51.1 50.7 50.7 50.7 51.1 Operating data Pulverization (-1/8") 81.6 82.0 80.7 83.2 84.1 82.0 82.3 Flue temp. (°F) 1900 1900 1900 1900 1900 1900 1900 Coking time (Hr. :min. ) 16:30 16:30 16:30 16:30 16:30 16:30 16:30 ILLINOIS STATE GEOLOGICAL SURVEY Table 5. - Coking Tests with Illinois No (Winter Period) Coal blend: 75% Illinois No. 6A (Mined 10-18-55) 25% Pocahontas 6A Run 156E Run 164E Run 169E Run 176E Run 184E Run 191E Run 198E Date of test 10-25-55 11-22-55 12-20-55 1-19-56 2-16-56 3-20-56 4-17-5 Days since mining 111. coal 7 35 63 93 121 154 182 Coke physical properties Tumbler test Stability 55.8 55.8 56.0 56.8 56.3 57.5 55.3 Hardness 66.0 66.9 66.1 65.3 65.8 66.4 65.6 Shatter test +2" 79.3 79.3 78.5 83.5 78.1 83.0 84.1 + l2 93.2 92.5 92.7 94.5 92.3 93.6 94.1 + 1" 97.0 97.0 97.0 97.5 97.0 97.3 96.8 Coke sizing +4" 6.1 4.1 8.0 7.2 7.1 10.0 9.0 4" x 3" 21.5 18.4 33.6 22.7 23.9 36.2 22.4 3" x 2" 43.1 46.1 35.6 44.2 43.7 33.0 41.0 2" x 1" 23.1 25.4 16.5 19.3 17.9 14.0 20.0 1" x i" 1.8 1.7 2.0 2.0 2.4 1.3 2.8 "IT 4.4 4.3 4.3 4.6 5.0 5.5 4.8 Average size (in.) 2.48 2.39 2.70 2.54 2.55 2.78 2.55 Apparent gravity .815 .809 .804 Coke yie .812 Ids {% of .809 coal ) .801 .824 (Coke at 3% M. - coal as received) Total 68.4 68.0 68.3 68.8 67.7 68.9 67.8 Furnace (+1") 64.2 64.0 64.0 64.3 62.7 64.2 62.7 Nut (1" x i") 1.2 1.1 1.4 1.4 1.6 0.9 1.9 Breeze (~g") 3.0 2.9 2.9 3.1 3.4 3.8 3.2 Expansion pressure Lbs. per sq. in. 1.07 1.05 1.11 1.08 1.15 0.99 1.20 Bulk density (Lbs. per cu. ft. ) 50.8 51.4 51.1 Oper 50.7 ating dat 50.7 a 50.7 51.1 Pulverization (-1/8") 82.5 84.2 82.4 80.0 86.0 85.5 83.6 Flue temp. (°F) 1900 1900 1900 1900 1900 1900 1900 Coking time (Hr. :min. ) 16:30 16:30 16:30 16:30 16:30 16:30 16:30 WEATHERING OF COALS DURING STORAGE Table 6. - Coking Tests with Illinois No. 6B (Winter Period) Coal blend: 75$ Illinois No. 6B (Mined 10-3-55) 25% Pocahontas Run 155E Run 161E Run 168E Run 174E Run 182E Run 188E Run 196E Date of test 10-14-55 11-10-55 12-15-55 1-12-56 2-9-56 3-8-56 4-5-5< Days since mining 111. coal 11 38 73 101 129 157 185 Coke phy sical properties Tumbler test Stability 56.5 56.1 55.4 56.2 55.9 55.0 55.6 Hardness 66.5 66.9 66.2 65.3 65.7 64.2 64.8 Shatter test +2" 78.2 80.3 81.0 82.0 80.4 87.5 83.9 Hi" 93.8 92.8 93.8 93.3 92.5 95.5 93.3 +1" 97.3 96.9 97.2 97.1 97.0 97.8 97.0 Coke sizing +4" 6.2 9.3 7.0 6.7 8.7 9.0 9.4 4" x 3" 28.6 32.8 25.7 28.8 25.4 27.2 23.3 3" x 2" 41.3 34.7 42.0 39.4 41.8 39.3 39.3 2" x 1" 17.0 16.6 18.3 17.0 16.8 16.6 19.3 1" x i" 1.9 2.1 2.0 2.3 2.3 2.0 2.4 5.0 4.5 5.0 5.8 5.0 5.9 6.3 Average size (in.) 2.60 2.71 2.57 2.58 2.61 2.62 2.54 Apparent gravity .818 .812 .802 Coke yie .817 ■Ids (% o .821 f coal) .825 .81! (Coke at 3% M. - coal as received) Total 68.0 68.3 68.4 68.2 67.3 68.4 68.0 Furnace (+1") 63.4 63.7 63.6 62.8 62.4 63.0 62.1 Nut (1" x i") 1.3 1.5 1.4 1.5 1.5 1.3 1.6 Breeze (4 n ) 3.3 3.1 3.4 3.9 3.4 4.1 4.3 Expansion pres sure Lb. per sq. in. 0.88 0.79 0.94 0.94 0.97 1.06 0.91 Bulk density (Lbs. per cu ft. ) 51.6 50.7 50.3 50.7 51.1 50.7 51.1 Operating data Pulverization (-1/8") 81.5 81.1 82.6 82.0 82.8 82.6 83.6 Flue temp. (°F) 1900 1900 1900 1900 1900 1900 1900 Coking time (Hr.:min.) 16:30 16:30 16:30 16:30 16:30 16:30 16:30 ILLINOIS STATE GEOLOGICAL SURVEY 8 these determinations. Other analytical data including the analysis and plastic properties of each coal blend, and analyses of the cokes produced, are shown in tables B, C, and D. Summer Storage The coals stored over the summer period, and tested at monthly intervals, oxidized far more rapidly than did those stored during the winter. The Gieseler fluidity of each coal decreased, and there were corresponding reductions in the fluidity of the blends.' The free swelling index of the individual coals did not appear to change greatly during storage, but this index decreased consistently on the blends prepared for coking. Analyses and plastic properties of the fresh coals are shown in table 7. Tables 8, 9, and 10 show the results of coking tests made during the summer, and tables E, F, G, and H of the appendix show plas- ticity trends and analyses of coals and blends throughout the period. Table 7. - Coals Placed in Summer Storage Analyses and Plastic Properties Coal M. V.M. F.C. Ash Sulfur F.S.I. Illinois No. 5 Mined 4-12-56 6.4 37.5 55.1 7.4 1.44 6i II lino is No. 6A Mined 5-8-56 8.1 37.9 54.3 7.8 1.25 4-£ II lino is No. 6B Mined 5-3-56 8.4 38.6 53.5 7.9 1.18 4§- Pocahontas 3.6 17.8 76.5 5.7 0.61 9 Plastic Properties Gieseler Fluidity Plastic Range (°C) Dial div. per min. at °C Softening Solidification Illinois No. 5 118 432 386 463 Illinois No. 6A 18 430 389 455 Illinois No. 6B 34 426 348 458 Pocahontas 73 486 439 509 Results of the pilot oven tests indicate that there was little oxidation in any of the three coals during the first 30 days of storage, and that any of these coals might be stored safely for that length of time. Following this 30-day pe- riod, breeze (minus 1/2" coke fines) production increased rapidly with the No. 6A coal blend, and less rapidly with the other two. Tests on the No. 6A coal were discontinued after four months because of excessive breeze production; No. 6B tests were continued for five months before breeze production made further testing impractical, and No. 5 coal tests were continued for the full six-months period. Even though the increase in coke breeze indicated weathering, the tumbler indices did not respond as quickly. Cokes made from No. 5 and No. 6B blends increased in stability and hardness during the first 60 days of coal storage. Stability did not fall below the value for fresh coal for over four months, and hardness for nearly as long. The coke made from No. 6A coal maintained prac- WEATHERING OF COALS DURING STORAGE Table 8. - Coking Tests with Illinois No. 5 (Summer Period) Date of test Days since mining 111, coal Tumbler test Stability Hardness Shatter test +2" +ii" +1" Coke sizing +4» 4" x 3" 3" x 2" 2" x 1" 1" x i" "ST Average size (in. Apparent gravity Total Furnace (+1") Nut (1" x i") Breeze (-§■'*) Lbs. per sq. in. Bulk density (Lbs. per cu. ft. ) Pulverization (-1/8") Flue temp. (°F) Coking time (Hr.:min.) Coal blend: 7b% Illinois No. 5 (M ined 4-12- •56) 25% Pocahontas Run 199E Run 205E Run 212E Run 222E Run 227E Run 235E 4-19 5-17 6-14 7-24 9-6 10-11 7 35 63 103 147 182 Coke physical properties 57.3 55.7 59.1 58.1 56.1 54.7 67.3 65.9 68.4 67.5 65.2 64.8 82.3 77.4 80.5 78.7 78.7 77.5 93.5 92.8 92.0 93.1 93.0 92.1 97.0 96.5 96.8 97.0 97.3 96.2 5.3 4.8 5.3 6.3 5.2 7.8 36.6 25.0 25.5 19.8 23.6 20.5 36.1 44.3 45.6 45.9 43.9 43.3 17.0 19.5 17.0 19.8 17.4 19.2 1.0 2.1 1.5 1.9 2.1 2.0 4.0 4.3 5.1 6.3 7.8 7.2 2.69 2.52 2.55 2.45 2.45 2.47 .806 .81: ! .830 .821 .828 .829 Coke yields (% of coal ) (Coke at 3% M. - < ;oal as received) 70.3 72.0 70.5 70.2 69.5 71.4 66.7 67.4 65.8 64.5 62.7 64.8 0.7 1.5 1.1 1.3 1.4 1.4 2.9 3.1 3.6 Expansion 4.4 pressure 5.4 5.2 1.36 1.27 1.19 0.95 0.86 0.80 51.5 51.1 51.1 Operatii 51.1 ig data 51.1 50.7 79.0 82.7 81.3 82.6 85.7 83.5 1900 1925 1925 1925 1925 1925 16:30 16:30 16:30 16:30 16:30 16:30 ILLINOIS STATE GEOLOGICAL SURVEY 10 Table 9. - Coking Tests with Illinois No. 6A (Summer Period) Coal blend: 75% Illinois No. 6A (Mined 5-8-56) 25% Pocahontas Date of test Days since mining 111. coal Tumbler test Stability Hardness Shatter test +2" +i" Coke sizing +4" 4" x 3" x 2" x 1" x 3" 2" 1" JLtt 2 Average size (in.) Apparent gravity Total Furnace (+1") Nut (1" x i") Breeze (-§-") Lbs. per sq. in. Bulk density (Lbs. per cu. ft. ) Pulverization (-1/8") Flue temp. (°F) Coking time (Hr. :min. ) Run 204E Run 21 IE Run 218E Run 226E Run 229E 5-15 6-12 7-10 8-7 9-13 7 35 63 91 128 Coke phys ical properties 55.5 54.6 55.6 49.8 47.9 66.2 66.2 65.5 61.9 58.3 73.5 79.5 73.3 75.7 79.7 91.0 93.5 91.1 90.7 92.0 96.8 97.3 95.9 95.9 95.3 5.3 3.9 7.2 5.8 6.6 22.9 21.1 23.8 23.0 23.9 42.4 47.4 40.4 43.4 37.7 21.9 19.9 18.6 17.2 17.4 2.4 2.5 1.8 1.8 2.6 5.0 5.2 8.2 8.8 11.8 2.46 2.43 2.48 2.44 2.39 .783 .813 .812 .816 .832 Coke yields {% of coal) ,Coke at 3% M. - coal as received ^ 69.4 68.7 68.8 67.2 68.6 64.3 63.4 62.0 60.1 58.7 1.7 1.7 1.2 1.2 1.8 3.4 3.6 5.6 5.9 8.1 1.14 51.5 Expansion pressure 1.00 0.82 0.84 51.1 51.1 51.1 0.75 51.1 Operating data 80.3 84.2 84.9 82.0 82.8 1925 1925 1925 1925 1925 16:30 16:30 16:30 16:30 16:30 11 WEATHERING OF COALS DURING STORAGE Table 10. - Coking Tests with Illinois No. 6B (Summer Period) Date of test Days since mining 111, coal Tumbler test Stability Hardness Shatter test +2" Hi" +1" Coke sizing +4" 4" x 3" 3" x 2" 2" x 1" 1" x i" Average size (in.) Apparent gravity Total Furnace (+1") Nut (1" x i") Breeze (-" Lbs. per sq. in. Bulk density (Lbs. per cu. ft. ) Pulverization (-1/8") Flue temp. (°F) Coking time (Hr. :min. Coal blend: 75% Illinois No . 6B (M ined 5-3-56) 25% Pocahontas Run 203E Run 209E Run 21 7E 1 Run 225E Run 228E Run 234E 5-10 6-5 7-3 8-2 9-11 10-9 7 33 61 91 131 159 Coke physical properties 55.9 57.3 58.0 56.8 56.6 54.2 65.9 66.4 67.2 65.1 64.5 62.7 80.6 79.1 77.8 79.5 82.2 77.3 93.4 93.8 93.1 92.4 95.6 92.8 97.1 97.7 97.0 96.9 97.0 97.2 7.9 4.6 4.8 6.9 8.1 6.5 36.5 21.9 24.0 21.9 25.4 25.0 32.5 48.1 43.9 44.3 38.3 36.7 16.8 18.2 18.8 17.0 18.1 20.2 1.8 2.3 2.1 2.1 1.7 1.5 4.5 4.9 6.4 7.8 8.4 10.1 2.72 2.48 2.47 2.46 2.52 2.42 .793 .790 .798 .807 .802 .816 68.7 64.4 1.2 3.1 1 .15 51.4 Coke yields (% of coal) (Coke at 3% M. - coal as received) 68.5 67.0 68.0 68.5 63.6 61.3 61.4 61.6 1.5 1.4 1.4 1.1 3.4 4.3 5.2 5.8 Expansion pressure 1.06 0.86 51.1 51.1 51.1 77.5 83.2 1925 1925 16:30 16:30 Operating data 84.3 83.4 1925 1925 16:30 16:30 0.87 51.1 84.7 1925 16:30 69.8 61.8 1.0 7.0 0.89 50.7 86.4 1925 16:30 ILLINOIS STATE GEOLOGICAL SURVEY 12 tically constant tumbler indices for 60 days, after which the quality deterio- rated rapidly. Expansion pressure exerted by all blends decreased from the start. The pressure exerted by No. 5 and No. 6B blends dropped slowly for 60 days and then changed more rapidly. A substantial drop in pressure occurred after 30 days with the No. 6A blend, indicating more rapid weathering. Cokes from all blends showed a definite trend upward in apparent gravity. Here again, No. 5 showed the least change, and No. 6A the greatest. All of these critical properties of the cokes are plotted against time of storage in figures 1 through 5. Judging from the analytical and pilot plant tests, it is evident that No. 5 coal resists oxidation longer than coals from No. 6 seam, and that coal No. 5 might be stocked for as long as 60 days in summer weather without serious ef- fects. It would appear, however, that the No. 6 coals should not be stocked longer than 30 days in the summer. The two No. 6 seam coals tested give evidence that coals from different areas in this seam may produce cokes of equal quality when fresh, but may differ in their ability to withstand weathering beyond the 30-day period. We can not adequately explain this difference in coking properties. The Gieseler fluidity of the fresh No. 6B coal was nearly twice that of the fresh No. 6A. However, after 30 days storage their fluidities were approximately the same. Likewise, free swelling indices of the two coals were practically identical throughout the period. Therefore, tendencies of the two coals to weather at different rates after 30 days cannot be correlated directly with either of these properties. It is possible that the Pocahontas coal may have been partly responsible for the weathering trends noted throughout the summer series. Although this coal was fresh when stocked, and no change was noted in free swelling index over the six months, the fluidity did decrease with time. We plan to make an- other series of tests during summer weather with at least one of these coals in which the Pocahontas is stored under water to minimize any possible oxida- tion. SUMMARY AND CONCLUSIONS To summarize, we have studied the weathering properties of Illinois No. 5 and No. 6 coals stored out-of-doors in small conical piles so as to be subjected to a maximum amount of oxidation. We have found that these coals, in the size range 3" x 1", can be stocked during the six-months winter period without ap- preciable loss in coking properties. The same coals stocked during the sum- mer period of warm weather showed little effect of weathering during the first 30 days, but after two months storage their coking properties started to change, and became progressively poorer as storage continued. Changes were more gradual in the No. 5 coal which might be stocked safely beyond the 30 days pe- riod. No. 6 coals from two mines weathered differently during summer storage, one showing much greater loss in coking properties than the other. Early tests have shown, however, that coal from this seam might be kept without oxidation throughout the year by storing under water. 13 WEATHERING OF COALS DURING STORAGE From these tests we conclude that double -screened coal from No. 5 and No. 6 seams in southern Illinois, in the sizes being supplied to metallurgical coke plants, can be stocked safely in contact with air, and without packing, during the six-months winter period at temperatures prevailing in the Chicago and central Illinois district. In summer appreciable oxidation occurs during storage, although to a greater extent with No. 6 coal than with No. 5. It appears, however, that for best coking results none of these coals should be stocked in the usual storage piles in warm weather longer than 30 days. REFERENCES Jackman, H. W., 1946, Unpublished data at the Illinois State Geological Sur- vey, Urbana, 111. Jackman, H. W., et al., 1955, Coke oven to measure expansion pressure - modified Illinois oven: Illinois Geol. Survey Reprint Series 1955-E. Reed, F. H., et al., 1947, Use of Illinois coal for production of metallurgical coke: Illinois Geol. Survey Bull. 71. ILLINOIS STATE GEOLOGICAL, SURVEY 14 10 c Q> O i_ i_ CD y Vinter Sen\ 9S - - „ — X X — • x £~~ ' - H— X"" • f « — — - o -73 C - 1 30 60 90 120 Days since mining Illinois coal 150 180 •— No. 5 blend • — - No. 6A blend No. 6B blend 60 90 120 Days since mining Illinois coal 150 180 Fig. 1. - Coke breeze. 15 WEATHERING OF COALS DURING STORAGE 60 90 120 Days since mining Illinois coal No. 5 blend • No. 6A blend No. 6B blend 30 60 90 120 Days since mining Illinois coal 50 180 Fig. 2. - Tumbler stability. ILLINOIS STATE GEOLOGICAL SURVEY 16 70 (A W O I 60 55 1 1 Winter Series _»x° • X ~~ ■""■ X X 1 30 60 90 120 Days since mining Illinois coal 150 180 — No. 5 blend • No. 6A blend x- No. 6B blend 70 ■§ 65 o X 60 55 "1 Si immer Sen %-- _ 1 X \ \ • \ "^-X ""—^ \ *-• 1 30 60 90 120 Days since mining Illinois coal 150 180 Fig. 3. - Tumbler hardness. 17 WEATHERING OF COALS DURING STORAGE c d- 1.5 o> Q. £ 1.0 §0-5 Q. UJ 0.0 Winter Series o " o o ( » J_ ° lj V x X /K 30 60 90 120 Days since mining Illinois coal 150 180 No. 5 blend •■ No. 6A blend x- No. 6B blend 30 60 90 120 Days since mining Illinois coal 180 Fig. 4. - Expansion pressure. ILLINOIS STATE GEOLOGICAL SURVEY 18 .84 >* .82 o a> .80 D a. a. < .78 .76 1 1 Winter Series o— —— —o ^ — — — •- — — o~~ "" o V i — 1 X • *~ -r* — XZ-- X • -.£" • x " l 30 60 90 120 Days since mining Illinois coal 150 180 No. 5 blend •— —— — —No. 6A blend x* No. 6B blend 30 60 90 120 Days since mining Illinois coal 50 180 Fig. 5. - Apparent gravity. 19 WEATHERING OF COALS DURING STORAGE APPENDIX Analyses of Coals and Cokes, and Other Pertinent Data Table A. - Plastic and Swelling Properties of Coals (Winter Period) Coal 111. No. 5 111. No. 6A Date 10-11-55 11- 8-55 12- 6-55 1-10-56 2- 7-56 3- 1-56 3-29-56 10-25-55 11-22-55 12-20-55 1-19-56 2-16-56 3-20-56 4-17-56 Maximum Gieseler fluidity F.S.I. 116 68 64 66 116 90 67 14 27 22 39 29 34 38 7 6 62 7 7 52" !* 5 6 5 5 5 Maximum Gieseler Coal Date fluidity f.s.: 111. No. 6B 10-14-55 10.8 52- 11-10-55 11 52- 12-15-55 11 6 1-12-56 8 5£ 2- 9-56 22 5 3- 8-56 15 5 4- 5-56 10 5 Pocahontas 10- 5-55 7 9 12- 6-55 4 9 1-24-56 3 9 2- 9-56 6 4 3- 1-56 4 9 3-23-56 5 9 Table B. Run 154E 160E 167E 173E 181E 186E 194E Coal Coke Coal Coke Coal Coke Coal Coke Coal Coke Coal Coke Coal Coke blend blend blend blend blend blend blend Analytical Data for Coke Runs Shown in Table 4 (Winter Period) Coal blend: lb% Illinois No. 5 25% Pocahontas Moisture-free basis M. V.M. F.C. 4.4 4.1 4.0 4.4 4.5 4.1 32.5 1.2 32.2 1.6 32.2 1.5 31.9 1.2 32.8 1.5 32.3 1.8 32.2 1.4 60.3 88.9 60.5 87.2 60.5 88.4 60.8 88.7 59.8 88.4 60.7 88.5 60.5 88.5 Ash 7.2 9.9 7.3 11.2 7.3 10.1 7.3 10.1 7.4 10.1 7.0 9.7 7.3 10.1 Sulfur Gieseler fluidity F.S.I, 7 1.47 1.17 1.39 1.05 1.41 1.07 1.39 1.12 1.45 0.99 1.38 1.04 1.38 1.10 16 10 14 14 25 9 13 6i !* 6 6* ILLINOIS STATE GEOLOGICAL SURVEY 20 Table C. - Analytical Data for Coke Runs Shown in Table 5 (Winter Period) : fluidity F.S.I. 4.5 5 11 5* Coal bl end : 75% 111 inois No. 6A 25% Poc ahontas M. Mo isture -free b asis Run V.M. F.C. Ash Sulfur Giesi 156E Coal blend 5.3 33.0 59.7 7.3 1.35 Coke 1.1 88.7 10.2 0.93 164E Coal blend 5.1 32.5 60.4 7.1 1.29 Coke 1.3 88.5 10.2 0.95 169E .Coal blend 4.8 33.5 59.1 7.4 1.33 Coke 1.1 88.5 10.4 0.95 176E Coal blend 5.5 33.9 58.8 7.3 1.28 Coke 1.6 88.0 10.4 0.95 184E Coal blend 5.6 32.9 59.8 7.3 1.31 Coke 1.5 88.2 10.3 0.94 191E Coal blend 5.2 33.6 59.1 7.3 1.33 Coke 1.6 88.2 10.2 0.90 198E Coal blend 5.1 33.5 59.1 7.4 1.48 Coke 1.8 87.8 10.4 1.05 14 Si- Table D. - Analytical Data for Coke Runs Shown in Table 6 (Winter Period) 6B Coal blend: 75% 111 inois No 25% Poc ahontas M. Mo isture -free basis Run V.M. F.C. Ash Sulfur 155E Coal blend 6.2 33.3 59.1 7.6 1.04 Coke 1.7 87.5 10.8 0.78 161E Coal blend 5.6 32.7 59.7 7.6 - Coke 1.5 87.8 10.7 0.75 168E Coal blend 4.4 32.9 59.5 7.6 1.05 Coke 1.1 88.3 10.6 0.74 174E Coal blend 5.5 32.4 60.1 7.5 0.99 Coke 1.6 87.9 10.5 0.79 182E Coal blend 5.8 33.0 59.3 7.7 0.99 Coke 1.5 88.1 10.4 0.75 188E Coal blend 6.1 32.5 60.0 7.5 1.01 Coke 1.6 87.8 10.6 0.75 196E Coal blend 6.3 33.6 59.1 7.3 1.01 Coke 1.6 87.9 10.5 0.77 F.S.I. 5 3.2 11 5^ 4+ 21 WEATHERING OF COALS DURING STORAGE Table E. - Plastic and Swelling Properties of Coals (Summer Period) Maximum Gieseler Coal Date fluidity F.S.I. 111. 4-19-56 118 6-g- No. 5 5-17-56 39 5g- 6-14-56 29 6 7-14-56 15 6i 9- 6-56 8 5i 10-11-56 7 si- ll 1. 5-15-56 18 4^ No. 6A 6-12-56 12 5 7-10-56 7 5i 8- 7-56 5 6 9-13-56 3 4 Table F. - Analytical Data for Coke Runs Shown in Table 8 (Summer Period) Coal blend: 75% Illinois No. 5 25% Pocahontas Moisture-free basis Ma ximum Gieseler Coal Date fl uidity F.S. 111. No. 6B 5-10-56 34 4 6- 5-56 13 5 7- 3-56 6 5 8- 2-56 6 9-11-56 3 10- 9-56 3 Pocahontas 4-12-56 73 9 7- 9-56 11 9 7-24-56 13 9 9-11-56 7 9 10-11-56 7 9 Run M. V.M. F.C. Ash Sulfur Gieseler fluidity F.S.I. 199E Coal blend 4.8 32.5 60.6 6.9 1.32 26 l\ Coke 1.7 88.9 9.4 1.04 205E Coal blend 4.9 32.1 60.9 7.0 1.25 10 5^ Coke 1.8 88.8 9.4 0.99 212E Coal blend 5.2 32.2 60.8 7.0 1.35 8 5§- Coke 1.5 89.0 9.5 1.06 222E Coal blend 5.4 32.0 61.1 6.9 1.34 5 5 Coke 1.3 89.3 9.4 1.05 227E Coal blend 4.8 31.6 61.5 6.9 1.29 3 4 Coke 1.2 89.0 9.8 1.04 235E Coal blend 3.7 31.9 60.9 7.2 1.43 3 5 Coke 1.0 89.2 9.8 1.11 ILLINOIS STATE GEOLOGICAL SURVEY 22 Table G. - Analytical Data for Coke Runs Shown in Table 9 (Summer Period) Coal bl end: 75% 111 25% Poc inois Nc ahontas . 6A M. Mo isture -free b asis Giesel er fluid: Lty Run V.M. F.C. Ash Sulfur F.S.I. 204E Coal Coke blend 6.5 33.2 1.4 59.9 89.2 6.9 9.4 1.11 0.81 7.8 6 211E Coal Coke blend 6.3 32.6 1.4 60.4 88.6 7.0 10.0 1.15 0.89 4 5 21 8E Coal Coke blend 6.5 32.6 1.5 60.7 88.6 6.7 9.9 1.13 0.88 3 4 226E Coal Coke blend 6.8 32.5 1.1 60.8 89.8 6.7 9.1 1.13 0.84 3 4 229E Coal Coke blend 5.4 31.9 1.3 61.5 89.0 6.6 9.7 1.11 0.84 2 3| Table H. - Ana lytica 1 Data for Coke Runs (Summer Period) Shown in Table 10 Coal bl end: 75% 111 25% Poc inois Nc ahontas i. 6B M. Mo: Lsture' -free b, asis Giesel er fluid Lty Run V.M. F.C. Ash Sul fur F.S.I. 203E Coal Coke blend 7.0 33.5 1.3 59.3 88.3 7.2 10.4 1.05 0.78 9 6 209E Coal Coke blend 6.5 32.9 1.4 60.0 88.5 7.1 10.1 1.04 0.80 6 $k 21 7E Coal Coke blend 5.6 32.2 1.3 60.8 88.6 7.0 10.1 1.02 0.77 3 4 225E Coal Coke blend 6.8 32.9 1.2 59.9 88.7 7.2 10.1 1.06 0.83 3 4 228E Coal Coke blend 5.8 33.4 1.4 59.4 88.6 7.2 10.0 1.05 0.83 2 4 234E Coal Coke blend 4.7 32.4 1.2 60.6 88.5 7.0 10.3 1.05 0.79 1 3i Illinois State Geological Survey Circular 227 22 p., 5 figs., 18 tables, 1957 ■IHI.'MW JUutdofjCvwofa/fl CIRCULAR 227 ILLINOIS STATE GEOLOGICAL SURVEY URBANA r««! '