INDUSTRIAL A N D ENGINEERING CHEMISTRY
k m b e r , 1944
In the modified expansion factor method (6)of Gamson and Wsteon the following values of pL/wl calculated from the densities et the normal boiling points of the components are used: Component CH4 CaHo CaHi n-CdHu n-CnHlr n-CeHu
a.36 4.42 4.76 6.04 6.16 6.24
-
Mol? Fraotion
Weight, Oram
0.3838 0.0766 0.0706 0.1129 0.3672
6.16 2.27 3.11
1.0000
1 [56 0.096 3.35
6.66
25.77 43.07
-
2:27 4 42
-
96.92 cc. 43.87
= 0.453 gram/cc. CONCLUSION
Ts,* R.
Pseudo
Pseudo PS Lb./Sq. Id.
132.0 41.6 47.0 86.5 302.2
268.3 63.8 48.6 62.2 173. a
-.
609.3
691.0
-
Pseudo T, 560/609 0.919; pseudo P, 1297/591 2.195. Using Figure 1 of Watson's original article ( d ) , the expansion factor for the entire mixture a t 1297 pounds per square inch and 100' F. equals 0.096: I,
Density
-
PIIWI
Calculation of liquid densities by this method is illustrated below for sample 8:
CEI CaE; CaHa n-CtHu n-CtEn
v.=-0.096
1165
6.56
311
4-
~
4-
25.77
m+ml
The use of apparent densities (3)and the modified expansion factor method (6)appear reliable for calculating the liquid densities of volatile hydrocarbon mixtures from the compositions of the mixtures. The average error in the use of apparent densities in the calculation of the liquid densities of the volatile hydrocarbon mixtures reported here is -0.50j0, and the average error in the use of the modified expansion factor method is -2.0%. LITERATURE CITED
(1) Natural Gasoline Assoc. of Am., Standard Factors for Volume Correction and Specific Gravity Conversion of Liquefied Petroleum Gases and Volatile Gasolines (adopted May, 1942): tables expanded Dec.. 1942. (2) Sage, B. H., Hicks, B. L., Lacey. W. N., A.P.I. Drilling and Production Practice, p. 402 (1938). (3) Standing, M. B.,and Kats, I). L.,Trans. Am. Inst. Minino Met. Engra., 146,169 (1942). (4) Watson, I(.M.,IND. ENQ.CaEm., 35,398 (1943). (6) Watson, K.M., private oommunication. PBIIINTED
before the Division of Petroleum Chemistry at the 106th Meet-
ing of the AMBRIOAN CEBMICAL SOCIBTT. Pitteburrh, Pa.
Plastic Characteristics of Coal CORRELATION WITH CHEMICAL AND PHYSICAL PROPERTIES AND PETROGRAPHIC COMPOSITION t l l HE chemical and physical proper-
R. E. BREWER
by the type or types of coal present. Earlier investigations (3,81, dd, $4) Central Experiment Station, showed that, with increasing temperaOf U. S. Bureau of Mines, Pittsburgh, Pa. ture in an inert atmosphere, the order of coal. The rank of a coal is a measure fusion of the banded ingredients of coal of the degree of metamorphism, or prois vitrain, clarain, and durain; that of the petrographic compogressive alteration, produced in the original coal-peat deposita nents is anthraxylon and translucent attritus. Opaque attritus by geological processes acting over very long periods of time. is much more stable toward heat. Coals containing high conThe type of a coal is determined by the kind of plant material centrations of opaque attritus either do not fuse or show only and the extent of the biochemical changes in the peat stage of poor fusion a t temperatures up to the formation of semicoke. coal formation; it is, therefore, an inherent characteristic of the Fusain, whether it occurs in bands or is dispersed among the coal. Correlation of various technologically important properother components, is practically unaffected by heat. Potoni6 ties of bituminous coals with r a d alone have been signifioant and Bosenick (29) found that fusain from Bismarck gas-flame for relatively homogeneous or bright coals. With less homogene(high-volatile) coal did not fuse up to 700' C., a t which temperao m coals more satisfactory correlations can usually be obtained ture the test was discontinued. Observations were made by a by considering also the type variation or petrographic composition of the particular coal. heating microscope on particles about 1 mm. in size a t a heating An attempt was made in this paper to discover what correlation rate of 5' C. per minute. Under the same test conditions with exists between rank and type factora and the data obtained in the same coal, vitrain fused a t about 410° C., clarain a t 430°, measurements of plastic properties of bituminous coking coals. and durein at 480". The relations found are suggestive and may assist in planning Pieters and Koopmans (Sf)heated coal, 0.5 to 1 mm. in size, future rasearch designed to provide more specific information. a t selected constant temperatures. Particles, consisting chiefly of vitrain in a good coking coal containing 26.8% of volatile ma+ RELATION OF RANK AND TYPE TO FUSION TEMPERATURE ter, divided into smaller rounded particles, and some changed into hollow spheres a t 410' C. Additional hollow spheres from vitrain In general, the fusion temperature of bituminous coking coals inareseee with increase in rank of the coals, but it is influenced also particles and spheres with partition walls from structured par-
1 vary ties of bitumino&-coking coals both with rank and
1166
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 36, No. 12
ticles (clarain) were formed a t 430". Particles, mainly durain, in a coal of higher rank containing 19.5% of volatile matter hardened as a result of slight decomposition at 407' C. and formed hollow spheres a t 485". I n a clarain of identical volatilematter content, the homogeneous portion of the particles formed hollow spheres with partition walls a t 500" C.
vealed some readily fusible material, and the sample was much less "opaque" or more translucent than other samples of corresp6nding high opaque attritus content. These properties indicate that a portion of this layer of the Eagle coal might more properly be regarded as translucent attritus. The plastic properties of this layer sample correspond well with those of coals
Correlations of technological properties with rank have proved unsatisfactory for certain bituminous coking coals. Thus, the carbonizing properties of a particular coal cannot always be predicted accurately from rank alone. The exceptional coals generally have one or more distinctive differences in either, or both, chemical and petrographic composition, as compared with other coals of the same rank. Earlier investigations indicated that the order and extent of fusion of whole coals and selected layer samples have a definite relation to petrographiccomposition. This paper presents a detailed study of chemical and petrographic composition and physical properties of nineteen
low-, medium-, and high-volatile A bituminous coals in relation to Gieseler maximum fluidity. These coals cover the range commonly used alone or in blends for production of commercial coke. Factors of chemical and petrographic composition found to contribute toward increasing the fluidity of a coal above that expected from its rank are high anthraxylon and translucent attritus contents and the presence of cannel coal. For coals of similar rank, those of higher physical strength generally show a higher maximum fluidity. Factors that reduce the fluidity of a coal below that expected from its rank are high contents of oxygen, ash, opaque attritus, and fusain.
Thiessen and Sprunk (64)studied a bright-coal layer composed of 38 area yo of anthraxylon, 48 of translucent attritus, 6 of opaque attritus, and 8 of fusain. The layer was taken from the Alma coal bed of West Virginia, which contained 39.7% (dry basis) of volatile matter. One-inch cubes from this layer were heated 5 C. intervals from 100" to 400' C. After the in duplicate at ' desired temperature was maintained within 5' C. for 2.5 hours, thin sections were prepared from each block and were examined microscopically. These investigators noted that "the point a t which many of the constituents begin to melt can be determined closely and definitely. However, they (the petrographic entities) do not necessarily completely disappear a t that temperature." Initial vacuoles were observed in anthraxylon strands of a certain type of anthraxylon at 335' to 340" C. and in another type of anthraxylon at 3550 to 360' C. Thus, it is implied that the melting temperature is different for anthraxylons of different derivation. Fragments of large strands of solid anthraxylon and fibrous anthraxylon may not have melted up to approximately 385' C. The heated samples lost their translucence rapidly beyond this temperature so that polished surfaces, rather than thin sections, had to be relied upon for the microscopic observation. The identification of constituents is more uncertain in polished preparations. Certain translucent constituents of the attritus melted at 340" to 345' C., but some of the attrital material had not melted at temperatures near 400" C. Brewer, Holmes, and Davis (5) determined the fusion properties of Pocahontas No. 3, Beckley, Pond Creek, Pittsburgh, High Splint, and Eagle bed coals and of two or more important layer samples taken from columnar sections of each of these six coals. The source and rank (1) of the first five are given in Table I. The Eagle coal was from the No. 3 mine in Logan County, W. Va. (19). The dry, mineral-matter-free fixed carbon content of the six whole coals and the thirteen layer samples ranged from 57.8 to 84.80J0. Each of the nineteen samples waa heated separately in the Davis plaatometer test (2, 5 ) at a rate of 3' C. per minute. Sixteen of the samples showed fusion. Except for one of the layers from the Eagle coal, the sum of the anthraxylon and trans' or more. lucent attritus contents in each sample was 61 area % This layer from the Eagle bed showed 9 area yo of anthraxylon, 31 of translucent attritus, 57 of opaque attritus, and 3 of fusain. One might expect that this layer sample would not fuse on account of the high content of opaque attritus. Microscopic examination of the opaque attritus in this sample, however, re-
containing higher total anthraxylon and translucent attritus contents. Added support for this reasoning is given by unpublished data obtained on an Eagle coal by the Gieseler plastometer test method. This Eagle coal showed a high maximum fluidity of 2400 dial divisions per minute at 429' C. The three nonfusing samples tested were layers from the Pocahontas No. 3, Pond Creek, and High Splint coal beds, and all contained 50 or more area % of opaque attritus and fusain. The three samples in the order named contained 84.8, 68.8, and 61.8% of dry, mineral-matter-free fixed carbon; therefore rank alone does not govern fusion properties. The sharp division observed here of fusing and nonfusing coab and their layer samples into two groups baaed on petrographia composition strongly supports the conclusion that coals containing large amounts of anthraxylon and translucent attritus show fusion, and that those containing large amounts of opaque attntua and fusain do not fuse. It may be concluded from the results obtained in the four investigations (5,61, 26,84)reviewed that the type of petrographio composition of coal is more important than rank in determining the fusion properties of bituminous coking coals. Prediction of the fusion characteristics of a coal, based solely on its rank, is not always reliable. CORRELATION OF RANK, MAXIMWW FLUIDITY, OXYGEN AND PETROGRAPHIC COMPOSITION
Table I gives the source and rank, expressed as dry, minerelmatter-free fixed carbon content (I), of nineteen low-volatile, medium-volatile, and high-volatile A bituminous coals for which both Gieseler plastometer data and petrographic analyses have been published. The coals were all tested in the Bureau of Mines-American Gas Association (BM-AGA) survey of American coals and bear the same coal number assigned in those tests. The first literature reference number in the last column of Table I refers to the publication describing the carbonizing propertim and petrographic composition of the individual coal. Additional reference numbers in the last column designate publicatione describing in more detail the plastic properties of certain coals. Table I1 divides the nineteen coals into two groups, based primarily on the bright-coal content of the individual coal. The six coals of the first group show an average of 97.2 area % of bright coal, whereas eleven of the thirteen coals of the second group give an average of 81.1 area %. Coals 58 and 54, because of their low content of bright coal, were not used in the average.
December, 1944
INDUSTRIAL AND ENGINEERING CHEMISTRY
1167
Corresponding anthraxylon contents for the two groups are 66.8 and 55.2 area %. The sum of the anthraxylon and translucent attritus contents amounts to 72 area % or more for each of the nineteen coals. Inasmuch as all the coals showed fusion, the itemized values for the content of opaque attritus and fusain are not given. Their s u m would be 28 area % or less for any individual coal. The coals within each group are arranged in order of decreasing dry, mineralmatter-free fixed carbon content. The total carbon content of the coals, computed on the same basis after finst deducting for any carbon occurring as carbonate, does not follow strictly the order of decreasing fixed carbon. Coals 41, 55, 58, 52, and 54 contained significant amounts of carbonate. The first group of coals shows a lower average oxygen content than the second group. Figure 1 gives tho relation between the logarithms of the Gieseler m&um fluidity value and the dry, mineral-matter-free fixed carbon content for the coals of Table 11. The Figure 1. Relation of Maximum Fluidity to Rank of Coal wide scattering of coordinate ~ o i n t srepresenting these two properties of -individual coals indicates that there is no smooth relation bedeviations. Coals 57 and 60 of the fist group in Table I1 tween maximum fluidity and rank. A study of the chemical and contain 90 and 93% of bright coal, respectively, and lie a t prupetrographic compositions and of certain physical properties of portional distances above line A. These coals show higher maxithese nineteen coals was found t o be of vslue in interpreting their mum fluidity than would be expected from coals of their respecplastic properties. Factors of the chemical and petrographic tive ranks. Coal 57 contains 5 area % of cannel coal, and coal compositions which contribute toward increasing the fluidity of 60 has high contents of anthraxylon and translucent attritus. a coal above that expected from ita rank are high anthraxylon These factors would increase the fluidity above that for coals conand translucent attritus and the preaence of cannel coal. Coals taining less of these constituents. showing higher strength, as indicated by friability tests and the The coordinate points for coals 56,41,55, 64,59, 53, 62 ,and 67 data of screen analyses, than coals of similar rank generally show lie close to line B of Figure 1. None of these coals show unusual a higher maximum fluidity. Factors that reduce the fluidity of chemical or petrographic characteristics. Coals 58, 61, 63, 52, a coal below that expected from its rank are high oxygen content, and 54 from the same group of Table I1 show pronounced deviahigh ash content, and other materials, such as opaque ettritus tions from line B. These five coals show one or more of the facand fusain, that are stable toward heat. tors cited above that influence the fluidity of coal. To relate these factors t o the plotted data in Figure 1, it was Although coal 58 is practically of the same rank rn coals 64 and found that the coals may be conveniently discussed with refer55, it shows a higher maximum fluidity. Coal 58 contains 11 ence to the two straight lines. Line A gives the relation between area % of cannel coal, which increases the fluidity. The column maximum fluidity and rank for the four 100% bright coalsof this coal in the mine has a characteristic steel-gray color, in47, 50, 65, and 66-of the first group in Table 11. B represents stead of the shiny-black luster of typical bright coals. The coal the bast straight line for these two properties of coals 56, 41, 55, 64, 59, 53, 6% and 67 of the secondgroup. Deviations of the coordinate points for coals 47, 50, 65, and 66 from line A are TABLE I. SOURCEAND RANKOF COALS small. These coals show no unusual Coal Fixed C, Literature chemical or petrographic characteristics. No. Bed Mine County State %" Citation It may be pointed out, however, that Coab of Low-Volatile Rank the slightly higher fluidity of coal 47, aa 17 Pocahontas No. 4 No. 4 Raleigh W. Va. 83.3 (14, 4) compared with that of coal 50, may have 47 Lower Kittanning No. 72 Cambria Pa. 82.9 60 Upper Kittannin No. 73 Cambria Pa. an explanation in the higher combined 66 Pocahontas No. d Buckeye No. 3 41 Beckley Winding Gulf No. 1 content of anthraxylon and translucent attritus. Coal 65 has a total of 98 area Coals of Medium-Volatile Rank % of anthraxylon and translucent attritus, 66 Sewell Wyoming Wyoming W. Va. 77.6 [@4) 64 Bakerstown No. 23 Tucker W.Va. 77.1 and its fluidity is slightly greater than 58 Lower Banner Keen Mountain Buchanan Va. 76.9 normal for a coal of its rank. Although 73.4 ...... Indiana Pa. 60 Lower Freeport coal 66 contains about the same total of Coals of High-Volatile A Rank these two petrographic components, it 65 No. 2 Bartoy contains more of the less fusible trans69 Upper Freeport 63 Pond Creek Mij&tic lucent attritus and has a higher oxygen 62 Powellton Elk Creek No. 1 61 No. 1 Bell No. 1 content than coal 65. These factors 67 Tnggart Lynch Nos. 30 d: 31 would suggest a slightly lower fluidity 63 Lpwer Hi nite Atlas h B. of M. Exptl. 52 Pittsbur than normal for a coal of the rank of 54 High S p h t Closplint 66 No. 5 Wilkeson-Miller coal 66. The relative positions of these four coals to line A are in harmony with Dry, mineral-matter-free basis. the suggested reasons for the slight
Kl
1168
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 36, No. 12
TABLE 11. CORRELATION OF RANK, MAXIMUKFLUIDITY, OXYGEN,AND PETROGBAPHIC COMPOSITION OF BM-AGA COALS Carbonizing Sample Dry Gieseler minerdmax. - tluiditv ___ matter-free LOP c. % Dip./ diyJ min. min. Fixed Total 83.3 91.3 3.0 0.4471 82.9 91.3 1.5 0.1761 82.1 90.9 1.2 0.0792 73.4 89.6 36 1.6563 68.4 87.0 60 1 ,7782 69.7 84.9 294 2.4683
97.2
Column Bample. Petro raphia Analyeis, Area Componsntm m-"-Iz1111Type Anlucent Semithraxettrisplint Splint Cannel ylon tu 6 67 30 0 68 24 0 66 1x 6 68 24 0 76 23 0 67 32 1.67 0.33 0.83 66.8 26.2
88 77 81 91 36' 86 69 74 01 76 76 84 330
2 6 16 3 63' 14 18 17 3 14 2 13 14a
~
COR1 No. 57 60 47 60 65 66
18 17 89 84 290 800 1250 1689 618 1125 186 708 6
Not used in average8.
Average 1.2653 1,2304 1.9494 1.9243 2.4624 2.9031 3.0969 3.2009 2.7143 3.0512 2.2672 2.8488 0.7782 Average
0,M received, % 3.7 3.7 3.6 6.3 6.6 7.9 6.11 3.6 4.b 4.3 4.8 4.8 7.4 7.7 7.3 11.0 7.9 9.8 8.2 10.6 6.96
breaks into columnar lumps and is harder than most ooals of similar rank. Sieve analyses of the carbonizing samples of coals 58, 64, and 55 gave cumulative percentages on the 2380-micron (%mesh) sieve of 46.2, 37.1, and 31.1%, respectively. Other anomalous characteristics of coal 58 were published recently (83). In particular, as compared with coals 64 and 55, coal 58 has a lower agglutinating value, gives a lower internal gas pressure during carbonization, produces a weaker coke of higher apparent specific gravity, and shows contraction, instead of expansion, in the sole-heated test oven. Coal 61 shows a lower maximum fluidity than would be expected for a coal of this rank. It contains only 54 area % of anthraxylon and has a high oxygen content of 11%. These factors decrease the fluidity of the coal. The lower-ranking, high-volatile A coals 63, 52, and 64 give appreciably lower fluidity than coals of slightly higher rank. The peak in maximum fluidity in bituminous coals of normal composition is reached in coals containing about 65% of dry, mineral-matter-free fixed carbon. Coal 63 contains 9.8% of oxygen and 23 area % of splint coal. The splint layer contains 15.7% of ash and approaches a bony coal in microstructure and composition. These properties cause coal 63 to have a lower maximum fluidity than coals 66 and 52, which are of lower rank but contain more anthraxylon. Coal 52 contains 8.2% of oxygen, but its anthraxylon content is appreciably higher than that of coal 63. The anthraxyloueattrital layer of coal 52 comprises 49.1 inches of the 63-inch column of the coal bed. The translucent attritus portion contains considerable resinous matter. Because of these properties coal 52 gives an appreciably higher maximum fluidity than is shown by coal 63 of higher rank. I n contrast to coal 52, coal 54 of identical dry, mineral-mattertree fixed carbon content gave a very low Gieseler maximum fluidity. The coal contains 53 area yo of splint and only 31 of anthraxylon. Microscopic examination of the splint portion reveaied high proportions of poorly fusible opaque to semiopaque constituents. Coal 54 contains a high oxygen content of 10.6%. These properties would account for the very low Gieseler maximum fluidity value of 6 dial divisions per minute.
Bright cod
90
loo 100 93 100 100
81.1
8.7
10 17 4 6 ' 0 0
13 9 6
10 23 3 63'
0
0 0
0 11" 0 0 0 0 0 0 0 0
9.2
60 40 60 67 30" 67 43 61 54 51 51 63 31'
20 39 23 21 494 26 37
56.2
28.0
30
26 32 32 22 41"
LITERATURE CITED
Am. Soo. for Testing Materials, Standards, P t . 111, Vol. 42. pp. 1-6 (1942)(A.S.A. M20.1-1938; A.S.T.M. D388-38). Brewer, R . E., and Atkinson, R . G., IND. ENG. CHEM.,ANAL. ED., 8,443-9 (1936). Brewer, R . E., Holmes, C. R . , and Davis, J. D . , IND. ENO. CHEW,32, 792-7 (1940). I b i d . . 32,930-4(1940). Brewer, R . E., and Triff, J. E., IND.ENO.CHmM., ANAL.ED..11. 242-7 (1939). (6) . . Davis, J. D . , Reynolds. D . A., Brewer, R . E., SDrunk. G. C.. and Sohmidt, L. D., U.8. Bur. Mines, Tech. Po& 628 (1941). (7) Davis, J. D . , Reynolds, D . A., Sprunk, G. C., Bnd Holmes, C. R.. I b i d . , 630 (1941). (8) I b i d . , 634 (1942). (9) Zbid., 644 (1942). (10) Zbid., 650 (1943). (11) Davis, J. D.,Reynolds, D. A., Sprunk, G. C., Holmes, C. H.. and McCartney, J. T., I b i d . , 649 (1942). (12) Fieldner, A. C., Davis, J. D., Brewer, R. E . , Selvig, W. A.. Reynolds, D . A., and Sprunk, G C.,Zbid., 594 (1939). (13) Fieldner, A. C., Davis, J. D . , Reynolds. D . A., Brewer, R. E.. Sprunk, G. C., snd Schmidt, L. D.. Zbid., 616 (1940). (14) Fieldner, A. C . , Davis, J. D . , Reynolda, D . A., Schmidt, L. D.. Brewer, R . E., Sprunk, G. C., and Holmes, C. R . , Ibid., 604 (1940). (16) Fieldner, A. C.,Davis, J. D . , Reynolds, D. A,, Selvig, W. A Sprunk, G. C., and Auvil. H. S.,Ibid., 599 (1939). (16) Fieldner, A. C., Davis, J. D., Selvig, W. A., Brewer, R. E.. Holmes, C. R . , Reynolds, D . A., and Sprunk, G. C., Ibid.. 601 (1939). (17) Fieldner, A. C.,Davis, J. D . , Selvig, W. A,, Reynolds, D . A.. Brewer, R. E., Sprunk, G . C., and Holmes, C. R.. Ibid., 621 (1941). Fieldoe;, A. C.,Davis, J. D., Selvig, W. A., Reynolds, D . A.. Sprunk, G. C., and Auvil, H . S.,Zbid., 596 (1939) Fieldner, A. C., Davis. J . D., Selvig, W. A., Thiessen, R., Reynolds, D. A., Holmes, C. R., and Sprunk, G. C., U. S. Bur Mines, Bull. 41 1 (1938). Fieldner, A. C.. Davis, J. D . , Thiessen, R., Selvig, W. A., Reynolds, D . A., andHolmea, C. R., U. 5. Bur. Mines, Tech. P a p r 595 (1939). Pieters. H. A. J., and Koopmans, H., Hst Gas, 52, 478-52 (1932); Fuel, 11, 447-51 (1932). Potoni6, R.. and Bosenick, G., Matt. preuss. geol. Landssamtalf. NO.19, 76-110 (1933). Reynolds, D. A., and Davis, J. D., U. 8. Bur. Mines, Rapt. Investigation 3749 (1944). Thiessen, R.,and Sprunk, G. C., Fuel, 13, 116-26 (1934).
ACKNOWLEDGMENT
The author is deeply indebted to J. D. Davis for valuable suggestions in the preparation of the manuscript.
Passmrmm before the Division of Gsa and Fuel Chemistry at the 108th Meeting of the AMmRrCAN CXUMICAL BOCIITT,New York, N. Y. Pubhhed by permission of the Director, U. 9. Bureau of Minea.
