INDUSTRIAL AND ENGINEERING CHEMISTRY
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(13) Gesell. fur chem. Ind., Basel, Swiss Patent 148,491 (Oct. 10, 1931). (14) Ibid., 150,789 and 150,790 (Feb. 2, 1932). (15) Goldberg, M. W., and Heineman, S. D., U. S.Patent 2,430,051 (Nov. 4,1947). (16) Hollabaugh, C. B., Burt, L. H., and Walsh, A. P., IXD.ENG. CHEK, 37, 943 (1945). (17) I. G. Farbenindustrie, A,-G., British Patent 306,132 (1932). (18) Izard, E. F., and Morgan, P. W., IND.ENG. CHEhf., 41, 617 (1949). (19) Malm, C. J., and Fordyce, C. R., Ibid., 32,405 (1940). (20) Malm, C. J., Fordyce, C. R., and Tanner, H. A., I b i d . , 34,430 (1942).
Vol. 42, No. 8
(21) Malm, C. J., Genung, L. B., TTilliams,R. F., Jr., and Pile, hl. A, IND.ENG.CHEW, A N ~ LED., . 16, 501 (1944). (22) Olpin, H. C., Gibson, S. A., and Jones, J. E., U. S.Patent 2,348,305 (May 9,1944). (23j Soc. des usines chimiques Rhone-Ponlenc, French Patent 672,220 (1929). (24) Staud, C. J., and Febber, C. S., U. S.Patent 1,900,871(Mar. 7, 1933). (25) Yackel, E. C., and Kenyon, W. O., J . Ant. Chem. SOC.,64, 121 (1942). RECEIVED January 16, 1950. Presented before the Division of Cellulose Chemistry a t t h e 116th 3Ieeting of t h e AVERICAS CHEWCALSOCIETY, Atlantic City, N. J.
Desulfurization of Coal during Carbonization U
HIGH-SULFUR INDIAN COAL J. I i o n .t 26A e 0 . 0023 -0.0030 loo,.? 'Tests 19, 18, a n d 18A on Illinois coal are same as tests Q, R , a n d T ,respectively, in earlier paper ( 1 ) . ii Kegative value for carbon oxysulfide results from solution of simultaneous equations used to calculate test d a t a obtained in determination of carlion disulfide and carbon oxysulfide. Ammonia gas started a t 500" C . ; total time of passage n-as 2.25 hr. d Two-stage treatment: Coke made under same conditions as in test 25 was cooled t o room temperature and used as sample in second treatment 1 h r . heating-up period a n d 2 additional hours at 800' C . D a t a represent both treatments based on coal sample. e Two-stage treatment: Coke made under same conditions as in tei;t 26 was cooled to room temperature and used as sample in second treatment--1.17 lir. heating-up period a n d 2 additional hours a t 800' C. D a t a represent both treatments based on coal sample.
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~
iiigs from the cokes. The percentage distributions of this soluble sulfur and of the sulfur left in the leached cokes TTeie plotted beparately . Figure 2 shows the percentages of sulfur in the cokes and the percentages of coal sulfur retained in the cokes plotted against giams of ammonia added for the nine tests given in Table 111. These percentages are higher than desirable for cokes intended for metallurgical uses, but considering the fact that these cokes were made from high-sulfur coals (Ledo, 7.47'3& and Illinois S o . 6, 3.557" total sulfur), the results offer promise that a modified technique might give cokes of lower sulfur content. The markedly increased desulfurization of Ledo coal compared to Illinois No. 6 coal, l\-hen these coals were carbonized under siniilar condition alone or with added sodium carbonate, lime, or ammonia, suggests that the total sulfur content and the ratio of organic to inorganic sulfur must influence the distribution of roal wlfur. The ratio of organic to inorganic sulfur in the Led0 (loa1 J\ as 7.09 to 0.38 or 18 66 to 1 and that in the Illinois coal 11 as 1.30 to 2.25 or 0.58 t o 1. Since 94.97, of the total sulfur in the Led0 coal was in organic form, as compared with only 36.6% in the Illinois coal, the sulfur distribution during carbonization of the t ~ coals o would be expected to be different. This different behavior was well illustrated by test 23 on Led0 coal and test 19 on Illinois coal in which the corresponding percentage distributions of coal sulfur (Figure 1) were: 40.5 and 53.3 in the cokes; 13.8 and 5.1 in the tars; 38.6 and 35.2 as hydrogen sulfide; and 3.2 and 2.4 as mercaptans. Stadnikov and Larina (9) also observed that when thc organic sulfur in coal was high
the sulfur in the primary tar a-as also high. The exact incchilniPm of the decomposition of the complex organic sulfur (wim pounds in coal during carbonization is not known with certainty, but hydrogen sulfide and other volatile sulfur compounds : I W known to be formed. Some evidence is available that this decomposition occurs a t lower temperatures than the dcwrnposition of iron pyrite. If t,his eiridence is valid, a grcatcxr proportion of the hydrogen sulfide and other volatile sulfur conpounds can escape as gases before high-temperature coking temperatures are reached. Volatile sulfur compounds, especially hydrogen sulfide, are known to react with hot coke to form (70111plexes viith carbon in which the sulfur is present in solid solutioii or is held physically by absorpt,ion. Once combined with the coke, t,he sulfur can be rcmoved only in insignificant amount 1)y further carbonization.
TABLE V. EFFECT OF ADDEDAMMONIA ON SULFUR REMOVAL .k'r 800" c. FROM LEDOC O A L PLUS INORG.4XIC h D l T 1 0 N AGEPiTS (Test conditions: ratc of ammonia addition, 1.46 g./hr.; heating-up period to 800° C., 1 hr.; carbonization a t 800: C., 1.5 hr.: 15-g. coal sample; through 20- o n 3 5 m e s h Tyler series sieves; 7.4770 suliur) Total Ammonia Addition Ammonia DecomCoke Obtained Coal Test Agent Added, posed, Sulfur, Sulfur in KO. Added. % G. % G. % Coke, % 25 None 2.18 36.9 8.82 3.51 27.6 28 FeO, 0 . 5 2.18 60.1 8.44 3.94 29.7 28A FeO, 1 . 0 2.18 83.0 8.40 4.41 33.1 27 FeO, 5 . 0 2.18 96.5 5.98 49.3 9.24 FeSI. 1 . 0 2.18 62.2 9 02 4.48 38 1 33" 32 b Bani, 1.0 2,18 53.3 9.ia 4.23 34.4 AlzOa, 0 . 2 5 2.18 37 62.1 8.81 3.59 28.2 38c 5.08 AlzOa. 0 . 2 5 62.6 7.63 3.06 20.8 36 -41203, 0 . 5 2.18 62.1 8.90 3.50 27.8 29 2.18 AlzOa, 1 . 0 64.7 8.58 3.31 25.4 30 AlzOs, 2 . 0 2.18 60.8 8.72 3.21 25.0 a Analysis of pyrite: Fe, 42.2%; S,49.070; balance mostlysilica, AI, C a , a n d JIg. b Sand was digested for 4 hr. in boiling 1 t o 1 hydrochloric acid-water solution, thoroughly washed with hot water, a n d dried before using. Two-stage treatment: Coke made under same conditions as i n test 37 was cooled to room temperature a n d used as sample i n second treatment-1 hr. heating-up period a n d 2 additional hours a t 800° C. D a t a represent both treatments based on coal sample.
0
1 2 3 4 INORGANIC AGENT ADDED, PERCENT
5
Figure 3. Effect of Added Dry hmmonia Gas on Sulfur Remo,al a t 800" C. from Led0 Coal plus Additions of Inorganic Oxides
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INDUSTRIAL AND ENGINEERING CHEMISTRY
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EFFECT O F ADDED FERROUS AND ALUMINUM OXIDES ON SULFUR REMOVAL
Another important difference between the Led0 and Illinois S o . 6 coals, which might be expected to influence the distribution of coal sulfur during carbonization, is the amount and composition of the ash. The ash content of the Led0 coal was only 1.370, whereas that of the Illinois coal was 15.6% or 12 times as much. The ferric oxide content of the ash from the Ledo coal was 35.5%; that from the Illinois coal was 21.9%. However, in the 15-gram coal samples used for carbonization, the iTon in the Led0 coal amounted to only 0.0484 gram, whereas that in the Illinois coal was 0.3584 gram or 7.4 times as much S o sulfur minerals could be positively identified in the thin section or hand specimen of the Led0 coal. Since the ash and iion contents of this coal are exceptionally low, a different proportional distribution of coal sulfur during carbonization with added ammonia may be expected, as compared with that in coals of moderate sulfur and mineral matter contents. To test the hypothesis that the very low iron content of Led0 coal must be an important factor both in reducing the proportion of coal sulfur retained in the coke and in decomposing only low percentages of ammonia, additions of iron compounds were made to the coal samples before carbonizing at 800" C. with added ammonia. Comparative tests using additions of sand and aluminum oxide also were made. Table V summarizes the results obtained on the coal alone and with inorganic agents added in various percentages. Figure 3 shows the percentages of sulfur in the cokes and percentages of coal sulfur retained in Figure 4. Effect of Temperature of Ammonia Introthe cokes plotted against percentages of added inorganic agents. duction on Sulfur Removal at 800' C. from Led0 Coal As expected, the tests with added ferrous oxide or iron pyrite plus Aluminum Oxide yielded cokes of higher sulfur contents than the coke from coal with any addition. Increasing the percentage of ferrous ovide from 0.5 to 1 t o 5% (tests 28, 28A, and 27) increased the sulfur more than offset because of ease of formation of stable sulfur comcontent of the cokes from 3.94 to 4.41 to 5.98%, as compared pounds in the cokes. Aluminum oxide, on the other hand, with 3.51% sulfur in the coke without added oxide (test 25). does not form a stable sulfide and hence in combination with Test 33 on the coal plus 1% iron pyrite gave a coke containing added ammonia tends to produce cokes of lower sulfur content. 4.4870 sulfur, which is slightly higher than the sulfur content Table VI summarizes the results of carbonization tests on Led0 (4.41%) of the coke from coal plus 1% ferrous oxide. The coal samples plus 0.25 and 1.0 percentage additions of aluminum addition of sand to the coal sample also increased the sulfur conoxide with ammonia introduced a t a constant rate a t 800" C. tent of the coke. On the other hand, the addition of aluminum and lower. The percentage decomposition of ammonia was of the oxide in various percentages t o the coal tended to reduce the same order of magnitude in the eight tests. For the samples sulfur content of the cokes, especially when the carbonization containing o,25y0 added aluminum oxide, increasing the time with ammonia was extended over a long period (test 38) or when of ammonia treatment a t 800" C. from 1.5 hours in test 37 to large amounts of aluminum oxide were added (tests 29 and 30). 3.5 hours in test 38 reduced the sulfur content of the coke from Higher percentages of ammonia were decomposed in all tests 3.59 t o 3.06%. With the same total time of ammonia treatment, of Led0 coal using added inorganic agents than when no addition 3.5 hours in each of tests 38, 39, and 40, but for 0, 20, and 30 was made, the highest value of 96.5% being attained in the test minutes below 800" C. and for 3.5, 3.17, and 3.0 hours a t 800" C. with 5 % ferrous oxide. Inorganic compounds, particularly oxides of iron, are known t o act catalytically in decomposing ammonia into hydrogen TABLEVI. EFFECTOF TEMPERATURE OF INTRODUCTION OF ADDEDAMMONIA ON SCLFCR and nitrogen. In the tests REMOVAL FROM LEDOCOALPLUS ADDITIONS OF ALUMINUM OXIDE with added aluminum oxide, (Test conditions: rate of ammonia. addition 1.45 g./hr.; heating-up period to 800' C., 1 hr.; 15-g coal saingle; increasing its percentage from through 20- on 35-desh Tyler series sieves; 7.47% sulfur) 0.25 to 2 did not appreciably Time of Ammonia Treatment change the percentage decomTotal Ammonia Ammonia Below At Ammonia DecomC I position of ammonia, as comTest AlaOs Started 800,O C., Added, posed, CokeaLEd Suli?:, in pared with the greatly increased No, Added, % at O C. numa Hr. Min. G. % G . Sulfur, % Coke, decomposition when ferrous 2.18 28.2 800 0 1.5 0 37 0.25 20.8 5.08 0 3.5 0 800 38 b 0.25 oxide was increased from 0.5 to 23.2 5.08 3.0 10 600 20 0.25 39 24.4 5 . 0 8 500 3 . 0 0 30 0 . 2 5 40 5%. Increasing the propor2.18 25.4 29 0 1.5 0 1.00 800 tion of hydrogen in the car25.3 2.54 700 15 1.5 0 1.00 31 20.7 5 . 8 0 3 . 5 0 700 1 . 0 0 30 35 0 bonization gases by decom25.8 2.90 1 . 0 40 1.00 600 20 34 position of ammonia during a From temperature given in column 3 up to 800' C. coal carbonization decreases e in test 37 was cooled to room temperature and used b Two-stage treatment: Coke made under same conditions a as sample in second treatment-1 hr. heating-up period and 2 additional hours at 800' C. Data represent both .~ the sulfur content of the coke. treatments based on coal sample. Coke made under same conditions as in test 31 was cooled to room temperature and 0 Two-stage treatment: In the present tests using used as sample in seoond treatment-I hr. heating-up period and 2 additional hours at 800' C. Data represent additions of ferrous oxide, iron both treatments based on coal sample. pyrite, or sand, this effect is ~
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Figure 5. Desulfurizing Effect of Increased Time of Treating Led0 Coal plus Aluminum Oxide at 800" C. with 5.08 Grams of Added Ammonia Gas
Vol. 42, No. 8
test 43, was to decrease the sulfur content of the cokes. Because of the relatively lower yield of coke and higher content of sulfur in the coke from test 51 (coal plus 0.257. aluniinum oxide) as compared with those from test 46 (coal plus 27, aluminum oxide), the same percentage of coal sulfur was retained in the cokes from these two 6-hour tests. Figure 5 shows the percentages of sulfur in the cokes arid the, percentages of c w d sulfur retained in the cokes plotted against hours of treatment for the seven tests in which the sitme total quantit,y of ammonia (5.08 grams) was added. Table VI11 summarizes the results of increased time of trratment a t 800" C. with ammonia added at, a uniform rate during carbonization of four Led0 coal samples plus 2'7, additions and of one sample plus a 0.257, addition of aluminum oxide. The p ~ r centage decomposition of ammonia gas was of the same order of magnitude in the five tests. The increased time of trcatnient with ammonia decreased the sulfur cont,ent of the cokes from the coal samples corit:iining 27. added aluminum oxide. In the two 6-hour tests, the coal plus 0.25% aluminum oxide (test 50) yielded a coke of higher sulfur content (2.360h) than did the coal plus 270 aluminum oxide (test 491, which gave a coke containing only 1.57y0 of sulfur. This latter coke had the lowrst sulfur content made from the Ledo coal; only 11.60/, of the original coal sulfur was retained. Figure 6 shows the percentages of sulfur in the cokes and the percentages of coal sulfur retained in the cokes plotted against the hours of treatment for t,he five tests (Table VIII) and for test>s37, 36, 29, and :30 (Table V). Table IX summarizes the effect of varying the heating-up period to and the carbonizing time a t 800" C. on the desulfurizat,ion of Ledo coal when carbonized alone and with added aluminum oxide, a,nd except for tests 23 and 55, with ammonia added at 800' C. at a. uniform rate of 1.45 grams per hour. The data, except tests 52 to 55, inclusive, have bcen included in t~adier tables to illustrate how certain other eupcrimental factors nffected the desulfurization of Ledo coal. In general, the p ~ r centage of sulfur in the coke was reduced \Then ammonia W R S added during carbonization, when the heating-up period a t 800" C. was increased, and when the percent,age of aluminum oxide n-a.5 increased. Thus, tests 23 and 55, made without adding aluniinum oxide or ammonia, gave high-sulfur cokes; t,he grrater desulfurization in test 55 is possibly explained hy t,he estentlecl
respectively, the sulfur content of thr coke increased correspondingly from 3.06 to 3.16 to 3.32%. The longer time of ammonia treatment at 800' C., therefore, \vas more effective in reducing the sulfur content of the coke than the same total time of treatment but with a part started a i 600" or 500' C. For the coal samples containing l.OyOadded aluminum osidr, the total times of ammonia treatment in tests 29, 31$ and 3 1 were 1.5, 1.75, and 2.0 hours, respectively. Corresponding times of treatment below 800' C. were 0, 15, and 20 minutes and at 800" C. were 1.5, 1.5, and 1.67 TABLE VII. EFFECTO F INCREASED T I h f E O F TRE.4TMEKT .kl' 800" c. JYITH hours, The sulfur contents of the cokes from the .kMMONIA ADDED I N S.4ME TOTAL QUANTITYO X SU1,FL-R RE>\rovAT, FROM three tests were 3.31, 3.30, and 3.439&, respecLEDOCOALPLUS ADDITIOXS OF r l ~ v ~ r r ? rOXIDE u~r tively. Treatment with ammonia gas for a total (Test conditions: total ammonia added, 5.08 8 . ; heating-up period t o 800' C., 1 hr.: 15-E. coal sample; through 20- on 35-mesh Tyler series sieves; 7.477, sulfur) time of 4 hours-30 minutes between 700' and R a t e of Ammonia 800' C. and 3.5 hours a t 800" C.-in test 35 gave Time a t Ammonia DecomCoal a coke containing only 2.85% sulfur. The results Test .41nOa 800° C., Addition, posed, Coke Obtained Sulfur in No. bdded, % Hr. G./Hr. I G . Sulfur, 70 Coke, 7c of these tests show that treatment with ammonia 62.5 8.60 3.31 25.4 2.54 2.0 42 2.0 at, temperatures below 800' C. does not improve 59.7 8.53 3.49 26 6 1.69 3.0 43 2.0 6 0 . 0 7 . 9 8 3 1 . 4 5 15 22 4 3 . 5 41 2 . 0 the desulfurizing action. Increased time of treat8.17 61 . O 21 6 2 96 1.27 4.0 2.0 44 ment a t 800" C. is much more effective in re20 3 8.52 2.67 60.8 1.02 5.0 2.0 45 8.72 2.40 70.0 18.7 0.846 6.0 46 2.0 ducing the sulfur content of the coke. Figure 4 8.14 2 58 62.1 0.846 18.7 6.0 0.25 51 shows these data graphically. The figures in parentheses equal the total hours of treatment with TABLEVIII. EFFECT O F INCRE.4SED TIME O F T R E A T M E N T .4T 800" C. ammonia below and at 800' C. WITH DRYh f M O N I A GAS BDDED AT A UXIFORM RATEO S SULFUR REJIOYAL. Table VI1 summarizes the results of increased FROM LEDOCOAL PLUS ADDlTIOXS O F ALUhIINUR.1 OXIDE time of treatment at 800" C. with the same total (Test conditions: r a t e of ammonia addition, 1.45 g./hr.; heating-up period t o 800' C.* 1 hr.; 15-g. coal sample; through 20- on 35-mesh Tyler series sievea; 7.477, sulfur) quantity of ammonla added during carbonization Total Ainmonia of Led0 coal plus 2 or O.25qc additions of alumiTime a t Ammonia DecomCoal posed, Coke Obtained Sulfln in num oxide. The percentages of ammonia deAdded, 800" C., Teat A1203 0. Sulfur, % Coke, '6 R Hr. Added, % G. KO. composed in all tests, except in test 46, were 3.5 5.08 60.0 7.98 3.16 22.4 41 2.0 of the same order of magnitude. The effect 19 6 59.7 8.44 2.60 47 2.0 4.0 5.80 6 . 0 7 . 2 5 6 0 . 3 8 . 1 9 2 . 4 3 17.8 48 2 . 0 of increased time of treatment with the same 11.6 49 2.0 6.0 8.70 61.0 8.26 1.57 50 0.25 6.0 8.70 61.7 7.98 2.36 16.8 quantity of ammonia of the six samples plus 2% additions of aluminum oxide, except in
August 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
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Figure 6. Desulfurizing Effect of Increased Time of Treating Led0 Coal plus Aluminum Oxide at 800' C. with Ammonia Gas Added at Rate of 1.45 Grams per Hour
a t a uniform rate of 1.45 grams per hour a t 800" C. The percentage decomposition of ammonia in each of the nine tests was about the same. The sulfur removal was greatest when the proportional time of heating a t 800' C. was a maximum. Thus, in the 4hour tests, test 58 (4 hours a t 800" C. and zero time a t 500' C.) yielded a coke containing 2.7oT0 sulfur or 19.4y0 of the original coal sulfur, as compared with appreciably higher-sulfur cokes from the three tests having shorter heating times a t 800' C. Likewise, in the 5-hour tests, test 62 (5 hours a t 800' C. and zero time a t 500" C.) gave coke containing 2.62% sulfur or 18.5% of the original coal sulfur, as compared with appreciably higher sulfur cokes from the four tests in which the times of heating a t 800' C. were shorter. Reductions i n the sulfur content of cokes resulted from an additional hour of heating a t 800' C,
TIME AT W C . , HOURS
Figure 7. Effect of Stage-Heating at 500' and 800' C. o n Sulfur Removal from Led0 Coal
TABLE IX. EFFECT OF VARYING THE HEATING-UP PERIOD TO AND REACTION TIMEAT 800" C. ON DESULFURIZATION OF LEDOCOALWITH AND WITHOUT ADDEDALUMINUM OXIDEAND
time of heating at 600' C. Tests 24 and 25, made with added ammonia, gave lower-sulfur cokes than did test 23 with no ammonia. The increawed removal of sulfur in test 25 may be explained by the increased proportion of total time of heating a t 800" C.-60y0 as compared with 46% in test 24. Tests 37, 38, and 50 (coal plus 0.25y0 added aluminum oxide) with heating-up periods of 1 hour each and carbonizing times of 1.5, 3.5, and 6.0 hours, respectively, gave cokes containing 3.59, 3.06, and 2.a6Y0 sulfur. Tests 30, 41, 47, 48, and 49 (coal plus 2% added aluminum oxide) with heating-up periods of 1 hour, each and carbonizing times of 1.5, 3.5, 4.0, 5.0, and 6.0 hours, respectively, gave cokes containing 3.21, 3.15, 2.60, 2.43, and 1.57% sulfur. The effect of maintaining the same total heating period (2.5 hours) but increasing the amount of added aluminum oxide was shown by tests 37, 36, 29, and 30, in which the percentages of added aluminum oxide were 0.25, 0.5, 1.0, and 2.0 and the percentages of sulfur in the cokes were 3.59, 3.50, 3.31, and 3.21, respectively. Maintaining a constant carbonizing time of 3.5 hours at 800" C. (tests 41, 52, 53, and 54) and increasing the heating-up period from 1 to 2.5 hours in 0.5-hour steps lowered the sulfur content of the cokes irregularly. Table X summarizes the effect of stage heating of Led0 coal for different periods of time a t 500' and 800' C. with ammonia added
1557
WITH
UNIFORM RATEOF ADDITION OF AXMONIA
(Test conditions: rate of ammonia addition, 1.45 g./hr.; 15-g. coal sample: through 20- on 35-mesh Tyler series sieves; 7.47% sulfur) Total Ammonia Heating Period, Hr. ~~~~~i~ D ~ ~ ~ ~ CoaI posed Coke Obtained Sulfur in At Added, AltOa TO Test No. Added, % 800° C. 800° C. % ' G. Sulfur, % Coke, % G. n 0 5.37 0 1.75 4.25 40.5 23 2.18 36.6 1.75 1.5 31.9 0 3 86 24 1.5 27.6 3.51 1 .o 2.18 36.8 25 0 4.20 0 0 2.75 30.7 0 3.25Q 55 3.59 2.18 62.1 1.5 28.2 0.25 1.0 37 62.6 5.08 3.5 20.8 3.06 38 1.0 0.25 8.70 6i.7 6.0 16.8 2.36 0.25 50 1 .o 1.5 3.50 2.18 62.1 27.8 1 .o 0.5 36 25.4 3.31 2.18 64.7 1.5 29 1 .o 1.0 2.18 60.8 25.0 3.21 1.5 30 1.0 2.0 22.4 3.15 5.08 60.0 3.5 41 2.0 1.0 5.08 26. I 52 3.40 60.4 3.5 1.5 2.0 5.08 63.0 2.79 3.5 53 2.0 22.0 2.0 6 2 . 5. 2.90 5.08 3.5 23.7 54 2.0 2.5 2.60 5.80 4.0 19.6 59.7 47 2.0 1.0 2.43 7.25 60.3 2.0 5.0 1.0 17.8 48 1.57 8.70 61 . O 49 2.0 6.0 1.0 11.6 a Heated to 600° C. in 1 hr. and 10 min., maintained at 600" C. for 1.5 hr., heated to 800° C. in 35 min., and maintained at 800' C . for 2.75 hr.
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O F LEDOCOALAT 500" AND 800" C. TABLE X. EFFECTOF STAGEHEATING WITH UNIFORM RATEOF ADDITION OF i l ~ ~ o x AT i a800" C .
(Test conditions: rate of ammonia addition;1.45 g./hr ' heating-up period to 500' C., 0.5 hr., from 500' to 800° C., 0.5 hour: 15-g. coal sampid; through 20- on 35-mesh Tyler series sieves; 7.52% sulfur) Total Ammonia Time at Time at Ammonia Decomposed, S O k e Obtained Su%?n i Added, Test 500° C., 800° C., No. Hr. Hr. % G. G. Sulfur, yo Coke, yo 0 4 5.80 2.70 19.4 1 3 4.35 3.15 22.9 2 26.5 2 2.90 3.60 1.45 4.19 1 31.6 3 7.25 2.62 5 18.5 0 4 20.5 1 5.80 2.81 3 4.35 3.16 23.3 64 2 2 2.90 4.12 31.1 65 3 1 1.45 4.27 32.5 66 4
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INDUSTRIAL AND ENGINEERING CHEMISTRY
(Compare tests 62 and 58, 63 and 59, 64 arid 60, and 65 and 61.) Figure 7 s h o m the percentages of sulfur in the cokes and the percentages of coal sulfur retained in the cokes plotted against hours of heating at, 800" C. for both the 4-hour and the 5-hour series of tests. By subtracting the plotted hours of heating, from 4 or 5 hours, depending on the test series, the corresponding time8 of heating at 500" C., as given in Table X, are obtained.
VoI. 42, No. 8
(3) Evans, C. L., Gas J., 244,545-7 (1944). (4) Gardner, E. D., Howell, S. P., and Jones, G.
W.,U . ,S.137tr Mines, Bull. 287 (1927). (5) Hoeven, B. J. C. van der, "Chemistry of Coal Utilization,'' Vol. 11, chap. 36, pp. 1648-9, Xew York, John Wiley 8: Sons,
(1) I31ewer,R. E., and Ghosh, .J. I
