INDUSTRIAL AND ENGINEERING CHEMISTRY Boruff and Buswell, IND. ENG.C H E x , 22, 931 (1930). Danok, U . S. Pub. Health Eng. Abstracts, E-919a,120. 22, 276 (1930). Hatfield, ISD.EBG.CHEST., Heukelekian and Rudolfs, Sewage W o r k s J . , 3, 3 (1931). Morgan and Beck, Ibid., 1, 46 (1928). EKQ.CHEW.,20, 837 (1926). Neave a n d Buswell, IND. N e a w and Buswell, J . Am. Chem. Soc., 52, 3308 (1930).
Vol. 24, No. 1
(9) Partridge, IND. ESG. CHEM.,23, 482 (1931). (10) Pearson and Buswell, Ibid., Anal. Ed., 3, 359 (1931). (11) Rudolfs a n d Fischer, Public W o r k s , 57, 171 (1926).
RECEIVED September 10, 1931. Presented before the Division of Water, Sewage, and Sanitation Chemistry a t the 82nd Meeting of the American Chemical Society, Buffalo, N. Y., August 31 to September 4, 1931.
Development of Dakota Lignite VI.
Effects of Blending and Mechanical Pressure on Coking of Lignite
A. W. GAUGER,J. R. TAYLOR, . ~ X DC . W. ULNIEN, Division of Mines and .Mining Experiments, University of North Dakota, Grand Forks, N. D. PRECARBONIZA TION of Dakota lignite temperatures. Thus, a t 815" C. p r o p e r t i e s of Dakota the gas distilled from Dakota 4500 eliminates most of the carbon dioride. lignite is that destruclignite contained 30 per cent carCarbonization of the char from precarbonized t i v e d i s t i l l a t i o n produces a dioxide, as against 43 per lignite mixed with Skelb' petroleum Pifch and residue consisting of a powdery cent a t 550" C.and 62 per cent certain bituminous coals yields a$rm coke. char instead of the a d h e r e n t at 400" C . ( 1 ) . It must be recoke o b t a i n e d under similar membered, however, that the abklechanical pressure during carbonization has conditions from most h i g h e r solute yield of carbon dioxide a markedeffect on the structure ofthesolid residue. rank coals. If a commercially was higher a t the higher temAddition of aluminum chloride hydrate greatly s u c c e s s f u l p r o c e s s of manuperatures, the variation in peraids the formation of a coke residue. facturing a suitable domestic centage being due to the much c o k e f r o m l i g n i t e could be more rapid increase in quantity devised, the development of the vast deposits of S o r t h of combustible constituents with temperature. Dakota would be stimulated by additional market outlets. EFFECTS OF BLENDING The University of Korth Dakota, as part of its work in developing the mineral resources of the state, has been engaged The lignite was crushed to 0.5-cm. size and precarbonized in a study of the carbonization of lignite under different for 1 hour a t 450" C. in an iron retort. The residue was conditions for a number of years. This paper briefly pre- ground t o pass a 14-mesh sieve and kept in sealed Mason sents some of the data obtained during the past three years. jars until required. Table I gives the proximate analysis Gauger and Salley ( 2 ) demonstrated that addition of cer- of the original lignite and the char (450" C.), calculated to tain inorganic materials-notably AlClp.6H20-to the lig- the dry basis. Mixtures were made of this char and difnite before carbonization influenced the process so markedly ferent tars and pitches, the method of mixing being varied that an adherent solid residue,. which they termed pseudo- to suit the material. In every case an attempt was made coke, was obtained instead of the usual powdery char. The to insure thorough mixing. work has since been extended t o a study of the effect of blending lignite, both raw and partially carbonized, with certain TABLEI. PROXIYATE ANALYSESOF LIGNITE.4UD CHAR OY DRYBASIS organic materials for the purpose of producing a domestic VOL.4TILE FIXED B. T. E. coke and a suitable combustible gas. MATTER CARBOX .4sx PER L E . Ordinarily the distillation of lignite yields a gas rich in Original lignite 45 3 47.9 6 S 11,040 450' ohm 19 0 67 7 12.4 12,110 carbon dioxide. It was observed in some other experimental work that carbon dioxide is given off from lignite a t comThe mixture was then formed into briquets in a cupel paratively low temperatures, from which the senior author surmised that it might be possible to remove a large portion of machine and carbonized in an aluminum or nichrome retort, this noncombustible gas by precarbonization a t some tem- depending upon the temperature of carbonization. After perature below that of ordinary low-temperature carboniza- retorting, the residue was examined and the gas analyzed. tion. A study was made of the effect of temperature on the S o attempt was made to obtain tar yields because of the yield and composition of gas from the destructive distilla- difficulty in separating the tar from the water with any detion of lignite. These experiments were carried out in an gree of accuracy. The following materials were tested for effect upon coking apparatus consisting of an aluminum retort, tar condenser, and gas holder with continuous-sampling device. The set- of lignite char: up was essentially the same as that described by Gauger 1 . Bituminous coal-tar pitch. and Salley ( 2 ) . 2. Skelly pitch, consisting of a petroleum residue described by The results which were obtained are represented graphi- Rittman as "Bituminous Coal from Petroleum." The proximate cally in Figure 1. Inspection of this figure indicates that analysis was volatile matter 45 per cent, fixed carbon 51 per cent, per cent (.5). a t approximately 450" C. the ratio of carbon dioxide to total ash3. 4 Illinois bituminous coal, received from S. W. Parr of the combustible gases is a t a maximum. That temperature University of Illinois. This coal swells and blisters badly on was, therefore, selected as the desirable precarbonization carbonization. 4. Red Diamond coal mined in Tennessee. temperature, No attempt was made t o distil at tempera5. Blue Diamond coal mined in Kentucky. tures in excess of 550" C., previous experiments in the School 6. Gold Edge coal mined in eastern Kentucky. of Mines having demonstrated that the gases contained a 7. Wheelwright coal, a gas coal mined in West Virginia and lower percentage of carbon dioxide a t the more elevated used by the local gas company.
0
S E of the characteristic
c.
mix: 15 grains liqite char, 10 grains of the coal t o lie I h d e d , 1.25 granis of AIC18~RH,0,and 8 grams of water. The cokes resulting from the hlend plus alrirniniiiii chloride hydrate are all of il harder denser structure than the blends :ilme, This i s particularly noticeable in the case of tlie I'uriLlroritas-lirrnite blend wliere the difference is vcrv nruiiii:
The apparent coniplck blending of the Pocalioiitas ailri SKELLY I'ITCH. 'PIX results with Skclly p i t r l r iidicat,cd ligriite gave a coke structure that was worthy of further a wetting of the surface oS thc lignite char particles by tho study. A series iv-as run, varying the ainmint of i'ocahontan pitdl during tlie carbonisatim; lience cxperirnents wcrc i n the l h i d in order to determine tiow little I'ocahontas carried out to determine the niost favorable mixture and tlie could be added and still have the characteristic coking. effect OS aliirrrinum chloride nn the coke structiire. The liest 'PIX rrrixcs used WFTO: results were obtained wlieii 25 grains of lignitr: char mr:ri! iriised with 1.29 grains AICIa4fMf and 3 grains nf pitcis. M I X L1,iNII.E Carn I'oc.,eoNT*s Wnrs" Airiouiits below that quantity nf pitcli gave iiifcrior cementGr'XPU C ~ ~ Omnix ~ 8 ing oE the particles, and ainouiits above seemed tr, have no li 10 8 9 8 18 added cfSect on the irardness of tho resulting coke. c 17 8 8 L) 18 7 8 Comparison of the results with earlier results obtained E: 10 a 8 in this laboratory indicates that tlie proport,iori of :M~I~ciIl~O P 20 5 8
I:
L
A
B
FIGURE 2. Rmroue FROM COKINGI,~I;WTI:Ceair, wrre
required to produce a firm w k c l i l i e st,rurturii can be cut duwn materially (from d i o i t t 20 per cent to aliout 4 Iier cent) iiy the admixture of 1 0 per cent Skrlly pitch. I4'igrirc 2 sliom the chars resultirig Srwi thr? Siillorving niixtrircs:
ASU
C wrrmtir Duwtin
Figure 3 sbons plititiimicrographs of five of tire resulting chars. Tlie letters below the photograplis correspond t o tile lctkrs in tlie above table silowing the mixes. All were iringnified approximately 15 diinneters. The first tlircc iriixtures sliowed considerablc widenee of swelling and gave A. Lignite char dona. a good hard-coke struature. I), E, and F slrowed no eviB. Lignite char, 25 grams; Skdly pitch, 3 grains. c, ~ i char, ~25 grams; ~ skelly i pitch, ~ 3 grams; r l ~ ~ 1 3 . dence OS swelling and, though hlendirig was evidenced, there was apparently not enough binder tn make tire characteristic ti€IrO, 1.25 grams.
1 N D I1 S T 11 I A 1,
A N r) E N G I N 1:' P; II 1 N G
C € I E 21 1 S 'll H Y
D
C
A
F
E
vrutinr.: 3.
VoI. 24, No. 1
or
I'"oTorIcnol;n*Ptia
LlGNIiP: C H A R
-l'ocheo.mns
COhL C0KX:S
iiard iam~uscoke alructure. hIix c, which hits the nrtii, Since it is cornpined largely of ccliulose fibers, resins, a d of iior1-coking to coking of 68::%2,conrpares very favtmlily lignin, the manufacture of a binder for coking lignite from with the 70:30 ratio as found by 1,ander and XcKay 0).i t seemed entirely feasible. In order to disint,egrate the Table TI gives the analysis of the gas frum thP carlmnisa- straw, the following treatment,s were used: tion of three of the a b o w i~lends. Heatin= with caustic soda wlution under ~ r e ~ ~ z r ~ ? .
ma1114
B , , ~ ~ "coI ,~
E
B
%,3 2.1
zLL.
oz
" , ~ 2,c
0.8
1.6
i:u
I,;
clil
,I.v
11,2 14.0 13.1
Z . 8 0 . 3 0 . 5 8 2 . 2 13.3 11.8
Per ton biandod c,lB~
cc.
~ ~ , , ;
fi7.s
blendrii
cu,i*.
J3,300
33.200 32.800
10.R24 10,1116
'hmMAL
v,,,.~,; B.t.ia./ cu./r. 40'J 409
370
Although the volume data. in Table I1 cannot be taken quantitatively exact because of leakage in the retort, the results are in close enough agreement to indicate that the carbonization of lignite char with Pocahontas coal gives a. gas of high enough heat value to be easily carbureted t o the standards set for city gas. The carbon dioxide content is worthy of partirular note. The carbon dioxide content of the gas from high-temperature carbonization of raw ligof the uite is from 20 to :10 per cent. I3y ~~reecarhonizati~m lignite, this has been reduced so that the gas from t,lic blending of 1ignit.e and bituminous contains as little RS 2.0 to 3.0 per cent carbon dioxide. This reduction greatly iucreases the heat value and reduces the inert content of t.he gas. The proximate analysis of the cokc resulting from Blend A is as follows: a8
VOL*T&&
MAlTSR
:%le
)i,xao c*iiao..
86.01
.ha 111.82
13. T. u. Y l 13,060
X
LLI.
WHBAT-STRA~ I'ITCI~ES. Wheat straw constitutes one of the abundant waste materia,ls produced in irorth Dakota.
The tar liquors were aeparutcti ironi the disintegrated fibers and then concentrated into a pitch. Mixtures were made up with ground precarbonieed lignite in the cupel machine and t,Ben carbonized at j25" C., in ~ I aluminum L retort. The results obtained with the pitch from treatrnent oE straw with chemical reagents were entirely unsatisEactory in so far as the pliysical structure of the solid residue was concerned. On the ot.her hand, the pitch obtained by t,reatnic.ot of straw with steam under pressure, &s well as hy destrrict,ive distillation, proved to he very effective in coke product,ioii. Tire most favorable mixture proved t o be 8084 per cent precarbonized lignite, ground to 30 mesh, and 16-20 per cent straw pitch, either with or without R small amount of AICh.BI-I,O added as catalyst. The best results were obtained with the pitch from destructive distillation of straw, hut this does not appear to be economically feasible because of the low yield (4-10 per cent) of the weight of straw. Since the steam digest,ion produces a disintegated cellulose fiber that can be used in the manufacture of insulating and pulp board, such an industry would furnish a bv-r)roduct which could be used in cokine .. lignite. EFFECT OF b k l i A N I C A l , k'1LESSUP.E ON
CARBoi%lz.hl'lON
Experiments indicated that the pressure of briquetting had a favorable influence on the coke structure. Because
I N I': IS 1% I u (i
(:
I.: $1 I s.r ti y
39
pressur
