INDUSTRIAL A N D ENGINEERING CHEMISTRY WaUing, C . , Briggs, E. R., Wolfstirn, K. B., and Mayo, F. R.. Ibid., 70,1537 (1948). Watson, P. D., Im. ENG). CHEM.,40, 1393 (1948). Wegler, R.,Angew. Chem., A60, 88 (1948). Wheeler, D. H., Im. ENQ.CHEM.,41,252 (1949). Whitmore, F.C.,Chem. Eng. News, 26, 668 (1948). Wiley, R. H.,and Smith, N. R., J . Am. Chem. Sac., 70, 1660 (1948).
Wiley, R. H., and Smith, N. R.,J. Polymer Sci., 3,444 (1948). Willictms, R.,Jr., Chem. Eng., 55,118 (1948).
mz
Vol. 41, No. 9
(177) Willis, J. M.,Wakefield, L. B., Pokier, R. H., and Glymph, E.M., IND. ENO.CHEM., 40,2210(1948). (178) Wilson, J. W.,and Pfan, E. S.,Zbid., 40,530 (1948). (179) Winding. C . C.,Ibid., 40,1643 (1948). (180) Wittbaroker, E.L.,Houtz, R. C., and Watkins, W. W., Zbid., 40, 876 (1848). (181) ZaPPt R.L.~zh.td.~ 40,1508 (1948). (182) Zoss, A. O . , Ilitnford, W. E., and Schildknecht, C. E.,Ibid., 41,73 (1949). R ~ C E X VJune E D 11, 1949.
Coal and Shale CHARLES H. PRlEN
UNIVERSITY OF DENVER, DENVER, C O L O .
I
N ACCORDANCE with the policy established for the initial review in this series, i t is the intent of this section to summarize developments occurring not only in the field of coal and oil shale pyrolysis itself, but to include as well those corollary subjects which relate thereto. Thus, in addition t o references on the mechanism and methods of pyrolysis of these substances, the paper also discusses the raw materials, products and byproducts of thermal decomposition, oven and retort equipment improvements, and procedures for analysis and testing. The majority of the references to gasification have been omitted, except where not clearly concerned with oxidation, hydrogenation, or some other unit process covered elsewhere in this review. The period spanned by the references given below is essentially that since the previous review (198),except for inadvertent omissions resulting from the unavailability of certain papers, or from the normal lag encountered in abstracting services. Due t o space limitations, only the more important papers of the past year have been selected for mention from the voluminous literature of the period. COAL PYROLYSIS GENERAL
A general discussion of the field of coal carbonization has been given in a series of papers of the World Power Conference, held in 1947. The more important of these have recently been summarized (18). As noted here and elsewhere by Ward (&%), modern coal utilization includes ( A ) its direct u8e as fuel, ( B ) its conversion t o more desirable fuels, and (C) ita conversion to organic chemicals. As pointed out by Stief (138),i t is highly desirable first to convert coal to more economical fuel forms by the carbonization and gasification processes included under B, rather than to employ i t directly for power and heat generation as such. These processes, of course, are intimately related to the synthetic oil processes now being investigated so intensively in the United States and elsewhere ( 1 6 ) , and t o the utilization of coal as a chemical raw material (266). Among the processes under consideration are both high and low temperature carbonization; complete gasification in the presence of air, steam, and oxygen; hydrogenation; solvent extraction followed by carbonization; and various chemical processes involving the coal tar, coal gas, and direct treatment with chemical reagents. Complete gasification processes often include a carbonizing chamber above a gas producer and make use of noncoking coals. The present status and future possibilities of these and other gasification processes have been reviewed b y Gumz (116) and by Hubmann (138). See also a recent symposium on production
of synthesis gas (18). The increasing use of high and medium volatility coals and of washing and drying processes for special purpose coals, in order to augment the coal types available for gasification and carbonization, are mentioned by Rose (811). A number of papers summarizing the progress of experiments in underground gasification of coal have been published (14, 196, 164). The application of these methods, particularly those developed in Russia (By), to British coal deposits has been discussed by Booth and Jolley (44, 46). A literature survey, primarily of Russian work, is appended. See also (238). Belgium developments are discussed elsewhere (16). The United States Bureau of Mines has published information obtained by the Solid Fuels Mission on coking practice in Germany (%IO), including methods of preparing metallurgical coke from noncoking coals, lignite carbonization, briquetting procedures, and a description of the slant-type Didier oven. The present status of the Polish coke industry has been discussed by Roga (808, BOQ), the French coke industry b y Cassan (64), and the current United States coke industry by Weiss (860). The last-named author emphasizes the need to conserve good coking coals, which are in short supply in America. A number of chapters of a new book on fuel technology (116) are devoted to the coking industry and t o carbonization processes. MECHANISM, KINETICS, THERMOCHEMISTRY
In an excellent discussion of the constitution of coal, Campardou points out (64) that complex mixtures of phenols and hydroxycarbon compounds analogous to those produced in carbonization are formed from coal and like solid combustibles on treatment with a slow current of superheated steam. Subsequent heating converts these substances t o viscous, plastic materials. Coal itself is apparently a solid hydrocarbon agglomerate enveloped by these plastic materials. Dry distillation a t high temperature destroys all but the benzene nuclei derived compounds, while slower low temperature distillation allows decomposition as well of the plasticlike materials, t o saturated hydrocarbons. Thus, the author concludes, coal is a real natural petroleum in a solid state, fixed by complex masses resulting from condensation and polymerization. A discussion of the structural changes occurring in coal substance during both its formation and during carbonization has also been given by McCulloch and others (178,810). Continuing his earlier work on carbonization mechanism, Gillet reports further data on coal composition, specifically with reference t o the molecular nature of coking-coal bitumens as deduced:
September 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
*
from x-ray crystallographic results (107). I n this connection attention is called to an x-ray investigation of the carbonization of coal tar pitch (106),in which a solid bitumen fraction, behaving crystallographically in a similar manner to coking coal bitumens, was found to be present. As a result of petrographic studies, Seyler (886)concludes that all metamorphic changes of coal proceed through a series of nine components derived from woody tissue, the main coal substance. All forms of subsequent carbonization, whether semicoking, gasretorting, or coking in the coke oven, proceed through these same nine steps as the temperature is raised. These steps can be identified by the optical properties of the components, as determined by microscopic observation. High temperature carbonization studies of coal carbonization at 600' to 900" C., in which air was completely eliminated from the retort, have recently been conducted in order to establish the mechanism of formation of oxides of nitrogen during pyrolysis. It was shown (176) that nitrogen oxides were produced only as a result of incomplete combustion of nitrogen by oxygen, and not from the action of oxygen from air on ammoniacal products of the coal. Rakovskii has carried out an investigation of coal tar formation during the coking process (199),by pyrolyzing primary tar formed at temperatures from 500" to 800" C., in the presence of various gases, including nitrogen and hydrocarbons. He demonstrated fhat chemical reaction between primary tar and hydrocarbon gas is a major factor in formation of the subsequent so-called secondary tar of carbonization. A theoretical discussion of the processes by which the tar seam (largest shrinkage crack) in a coke oven is produced, and of various definitions of rates of carbonization has been presented (846). Fundamental investigations on the coefficients of expansion of coals and carbonized ooals have been reported in the period under review. Tests were conducted on a high oxygen bituminous coal (I), a high carbon bituminous coal (11), and an anthracite coal (111), by Bangham (3@, to confirm the theory that expansion coefficients were determined more by molecular configuration than by physical structure. Coal I1 was found to yield a coke of significantly greater expansion coefficient than I. The coefficient for coal I11 was much less temperature dependent than I and 11,but varied with orientation with respect t o the bedding plane. Mains (178)found the swelling properties of coal during coking to be dependent on the bright constituents present, in contrast to the dull constituents, which shrink considerably in volume during coking. High vitrain and low durain content increased the danger of swelling, whereas 10 to 15% durain in the dull constituents was found to eliminate swelling. The effect of particle size and oven operating conditions on swelling were also studied. The influence of various wax and resin fractions extracted with selected organic solvents, on coal swelling is reported by Leroux
*
Studies of phase equilibria in the complex coal-gas system, a t low temperatures and elevated pressures up to 90 atmospheres have been reported by Chow (68), together with an illustration of the applicability of the data to plant design.
A
x
( 1 ~ ) .
R A W MATERIALS AND PROPERTIES
The use of various pretreating and blending processes to prepare a more suitable oven charge and to increase the range of coals suitable for coking has continued to receive increasing attention. The desirability of reducing mechanical degradation prior to the coal preparation processes to a minimum has been pointed out by Hague (118). The importance of minimizing differences in oxidation between the various components of the blend has been emphasized (136),and the effect of oxidation on agglutinating value, coking properties, and yields of pyrolysis products for a number of United States coals investigated (48, 84). A detailed account of coal sizing and coke preparation in several American plants is reported (66,97).
1907
A graphical method based on a series of six tests (calibration, moisture, ash content, ash fusibility, volatile matter, and swelling) has been advanced as 8 rapid method for coal selection for gasification and carbonization (66). A two-test (swelling and volatile content) method is $so described (83Q). A chart said to be applicable for predicting agglomerating and swelling power, coking power, and product and by-product yields from pyrolysis, for all coals of Permo-Carboniferous age throughout the world, is described by Mott (183). The determination of coking properties of United States coals and the behavior of the cokes produced therefrom is reviewed by Russell (616). A survey of the future reserves of coking coals in the United States and their characteristics has been reported by Becker (34). Additional data from the Bureau of MinesAGA survey of the carbonizing properties of American coals, which has been in progress for a number of years, is reported by Davis (83, 86). Specific papers on the coking coals of India (179),France (169), Chile (1O4),and Peru (100)have also been published. The relation of the moisture sorptive power of coals to their coking properties has been noted by several authors (46, 636). A further description of results of wetting coal with small quantities of anthracene oil to increase bulk weight is presented by Agroskin (1). An account of experimental investigations to determine the electrical resistivity of various coals, in connection with renewed efforts to consider the direct utilization of electricity for coke production, is presented elsewhere (I) by the same author. See also (188). The use of anthracite fines in coke production, their advantages and disadvantages, and a detailed account of experiences and observations of coke-plant operators who have used them is given in a recent bulletin of Pennsylvania State College (76). This is an extension of data reported earlier by the same source (76). Attention is also called to the work of the United States Bureau of Mines in this same field (178). Carbonization tests on four different crude peat samples, including product yields and thermal effects accompanying the pyrolysis, have been detailed by Widell (883). HIGH TEMPERATURE C A R B O N I Z A T I O N
Data on three processes for coking medium- to weakly-coking western coal are reported in a paper by Hamilton and Wolf (f81). Briquets were prepared in each case, and charged into ( A ) an electrically heated slot oven, ( B ) a Curran oven, and (C) a National fuel process retort. Continuing his work on the behavior of bituminous coals on heating, Macura (174)has studied the relation between shrinkage, ash, and volatile matter of a series of coals pyrolyzed at temperatures up to 1000" C. Experiments on the determination of coking power as a function of rate of carbonization and coal particle size were also conducted and the results applied to coke oven operation. The carbonization of coals subjected to conin blends with strong coking coals, Experiments recently conducted on the coking of mixtures of blast furnace dust and iron ore with coking coals (77) have shown the inferiority of such blends for coke production. A plant for the carbonization of French lignites a t temperatures up to 1200'C. and studies of the pyrolytic properties of these lignites has appeared (87). Methods for removal of organic sulfur from an Indian coal, by the addition of lime or calcium chloride and carbonization with or without a current of hydrogen, are given by Das (88). I n this connection see also a recent U. S. patent (86),in which low grade coal is treated with carbon monoxide a t 800' to 1000" C., with consequent loss of sulfur. A process has also recently been patented for improving coking properties of bituminous coals of high resin, wax, and oil content, by preliminary extraction with ethylene dichloride prior to pyrolysis (85'1).
INDUSTRIAL AND ENGINEERING CHEMISTRY
1908
LOW TEMPERATURE C A R B O N I Z A T I O N
The Office of Technical Services has issued a number of reports of processes and techniques for the low temperature carbonization of coal, with and without briquetting, as developed in Europe during the recent war. Particular attention is called to the reports of the I. G. Farbenindustrie (130)on the Hykoks process for low temperature carbonization of coal mixed with ( A ) partially hydrogenated coal or hydrogenation residues, (B)high sludge residues, and (C) sulfite waste liquors. See also (1659270). Christiansson (71)has issued a series of studies of tar formation by pyrolysis of Swedish peats. This is a continuation of earlier work on peat carbonization by the same author (69, 70),who has also recently described a group of tests on wet carbonization of peat in a high pressure autoclave (79). Further research in the latter category has also been performed by Teichert (843). Low temperature thermal decomposition of peat was also studied by Candea (67), who conducted hydrogenations on the semiooke produced as well. The specifications of peat suitable for coking have been outlined (217). A review on the low temperature Carbonization of bituminous coals has been published (161),along with results of experiments on production of synthesis gas from coke so obtained. Developments in this type of pyrolysis as applied t o German bituminous coals, and a description of three kinds of ovens-namely, heatedsurface, ceramic chamber, and recirculated-gas ovens-are given by Thau (9.46). The influence of reduced pressures on the yield of semicoke and all liquid carbonization products obtained up to 500 C. from subbituminous coal has been evaluated by Simek et al. (%'9). The apparatus employed for these experiments is described by Ludmila (17 1 ) . Studies of the behavior of the coals of particular countries of the world, when subjected to low temperature carbonization, have appeared during the period under review. Reference is particularly made to work on Indian coals (117, 180), and to the coals of Bavaria (153) and Upper Silesia (b36). The importance of low temperature carbonization in the production of synthetic oiI in Japan, particularly during the war, has been reported (109, 903). I n the United States experiments have recently and a plant constructed for been conducted on Ohio coals (1.46), the pyrolysis of an Illinois coal (10). Several patents are also worthy of special mention (163,235,2269). O
OVEN O P E R A T I O N
The problems accompanying aconoinical oven operation, including the efficient use of fuel, refractory life, waste heat recovery, etc., have been the subject of various papers during the review period. The more important of these are presented in this section. In discussing methods for increasing gas yields in coke plants, Wardner points out (258) that a minimum percentage of low volatile coal in the oven charge and uniform charging practice are more effective than such factors as rate of oil serubbing for Iight oil recovery. Summaries of eight additional methods of improvement are presented in a later article by the same author (857). A system for rating the efficiency of coke plants, based on the calorific value of the blends charged and of the products, has been suggested (919). The use of fully automatic producers to furnish fuel gas for a bench of West continuous retorts has been described (168). Solid deposits which occasionally block regenerators when external producers are used to fire ovens can be removed, it is claimed (SO), by evaporating a small quantity of tar oil into the gas. A patent for firing coke ovens with a mixture of a carrier gas (air, producer, etc.) and natural gasoline has been assigned to the Koppers Company (139). The apparatus and procedures for investigating the temperatures encountered in various sections of the ovens has been the subject of a few reports. Included among these are a study of
VOl. 41, No. 9
combustion temperatures in the heating system (S),the walls ol the oven (157,159), just below the crown (159), and in the charge itself (156). The recovery of the 5% of calorific value of the charge which is lost as sensible heat in the coke by the usua3 quenching methods is given by Keisalo (140). Applicatior to coke plants operated in conjunction with iron and steel mills i q noted by Savage (.E?80). Experiments on the effect of the number of gas-collecting takeoffpipes on the performance of a battery of Becker ovens have been carried out by Kustov (158). A comprehensive study or conditions existing in the gas stream system, from oven ascensior pipe to final coolers, has been made by Brown (68). Physicochemical data and equilibria in the system ammonia-carbor dioxide-hydrogen sulfide-hydrogen cyanide over liquid w a t e have been determined by Symnnn (95), in an attempt t o increase ammonia recovery, Cassan presents (65) an equation for determining the oytimurr. length of the coking period in an oven, based on the width and external temperature thereof. Facto1 s influencing refractor3 life of silica coke oven batteries are reviewed by Kerr and Taylor (1.41). Tar deposition in the by-product recovery system, the effect of carbonization, temperatures in its production, arld it* removal are analyzed by Than (s47). PRODUCTS AND BY-PRQDUCTS
A brief description of marketing and utilization of coke breeze and coke in burning appliances has been published in a reoent bulletin (8). Cooper (79) and Evans (93) review the status 0' by-product recovery processes in gas production in Great Britain including the disposal of surplus coke, liquor, and spent oxide Low boiling (below 100" C.) carbonization products fiom pea I have been studied (70). The purification of coke gas under pressure by the Kopperc process is described (36.4). Wet and dry processes for sulfur removal from gas have been reviewed by Marshall (178), whc concludes that the present trend is t o return to dry purification Equilibrium constants for a number of organic solvents employe6 for removal of sulfur are given by the S G A Organic Sulfur Committee (116). A detailed study and survey of organic sulfu, compounds in domestic gas has been completed by the Gas LZesearch Board (Great Britain) (166). A plant removing sulfur catalytkally is discussed (197). The conversion of coking gab t c synthesis gas by partial oxidation and catalytic hydrolysis of it^ constituents is noted by Sachsse (616). Schuftan (626) mentiont a low temperature process for ethylene recovery from coal gas A new plant for hydrogen cyanide recovery (for sale) from the acidic gases has been erected (23). I n a discussion of the economic trends in coal tar hydrocarbor (benzene, toluene, naphthalene) production, Weiss (669) emphasizes the growing competition from petroleum procesying Glarlc and Sowden present (7'4) a detailed discussion of the absorbing oils used for light oil recovery, including their purification corrosion characteristics, and the sludges formed therein. See also (181)~ Chemical purification of wash oil by the use of sodium hydroxide has been developed by the French Coal Board (611 The use of a low resin content activated carbon for benzenr recovery is mentioned by Rosendahl (616). A patcnt for the recovery of cyclopentadiene from light oil forerunnings haw been issued (86). KO process as yet seriously challenges the semidirect sulfate process for recovery of ammonia, according to a recent survel of American practice (266). The influence of synthetic ammoniz on the economics of this recovery is revipwed by Thau (648) and the production of ammonium compounds more profitable than the sulfate discussed by Grosskinsky (114). A process for manufacture of the sulfate by neutralization of spent pickling acid with coke oven ammonia has been patented (98). Attention is called in this latter connection to a previous report of a similar method (127).
September 1949
.
*
INDUSTRIAL AND ENGINEERING CHEMISTRY
The use of Sharples Autoejector centrifugal dryers for the deBydration of coal tar emulsion has been noted by Young (367, 868). Recent advances in tar distillation are reported by Curtis (81). An excellent series of papers has been published by Green ( 1 1 3 ) on the insoluble matter of coal tar, including data on freecarbon content, some inorganic constituents of the free carbon, and on coal t a r resins. The waste-disposal problems of the by-product coke industry have been the object of increasing attention, particularly in so far asdephenolizationof wasteliquorsisconcerned (181,189,192). A review of Polish methods of phenol recovery is given by Klosinski (148). The removal of phenols from ammoniacal coke plant liquor by use of a benzene solvent has been patented (148). See also (880). Phenol losses by vaporization from waste water used for coke quenching have been determined (112,187). A process for detoxification of cyanide-containing coke oven waste liquors is reported by Smith ($84). EQUIPMENT
In the following paragraphs a few of the more significan velopments in new equipment, and improvement in exis facilities for coal carbonization are summarized and discu The compilation is of necessity incomplete. A new Koppers-Becker battery of ovens capable of being fired with either coke oven gas, water gas, natural gas, producer gas, blast furnace gas, refinery gas, butane, or propane has been completed (184). A battery particularly adaptable of low volatile content has been designed by Wethly (262) Free expansion ovens and experiences in their use are by their inventor, Petit ( l a ) ,and by others (17,64,110). A distribution system and other improvements in under-jet ovens are the subject of several British patents (148, Ha). For additional new horizontal and vertical oven designs see (86,37,198,198). Two reports of the Gas Research Board (Great Britain) describe research on the refractory materials of retort settings (189, 160). The properties, of refractories in the gas industry are elaborat and by Chapman (66). Auxiliary devices for the oven-namely, charging ( 1 1 1 ) and discharging devices (291), self-sealing doors (94, l@), and tlilica Venturi gas burners (147)-have appeared in the patent literature of the period under review. A crank and connectingBO^ type of door remover is described ( l f ) which , replaces the usual rack and pinion design. A new Swedish regenerator for heating secondary air for the oven has been patented ( 4 ) . Of Interest also is a new design of electrostatic precipitator for tar removal, which consists of concentric sheet-iron cylinders between which are mounted wire electrodes, the tar-laden gas flowing up through the annular space between cylinders (189). 8
COKE PROPERTIES
A review of developments in the manufacture and quality of metallurgical cokes and in methods of testing coke has been presented by Thibaut ($49). A similar compilation for foundry coke has been published by the American Foundry Association (6). The British Coal Utilization Research Association has reviewed the literature relating to the utilization of coke for fuel and metallurgical purposes (8), as have also Cooke and Hutt (78). Details of grading coke into the sizes most suitable for specific duties are outlined by Boon (43). The influence of coking conditions on the microstructure of coke and tests for the determination of the latter were investigated by Onusaitis (191). It is proposed by Sapozhnikov (618) that the cracking of ooke st high temperature is a function of the interaction of the coals in the oven charge. Use of the thermal stability of coke, rather then drum tests, as an index of quality, is recommended. Stahl reports the results of a series of experiments to improve coke strength (887),in which it is shown that increased fineness of pulverization increases the strength of the coke produced.
1909
A method for the determination of the reactivity of coke to water vapor has been described by Delassus (86). I n this regard the reader is also referred to a publication of the Office of Technical Services (85). This latter source has also issued several reports on the combustibility of coke in oxygen and oxygen-air mixtures ($6, 158). The effect of coke quality on blast furnace operation has been the subject of a number of papers. Gardner (105) claims that the conventional physical tests now used are satisfactory for prediction of its performance in the furnace. In a recent article (170), Lowry presents an evaluation of the influence of ash and sulfur on blast furnace operation and pig iron quality. Chizhevskil attempts to determine a mathematical relation between coke combustibility and blast furnace performance (67),similar to that proposed by Syskovin 1943(840). A method of comparing the caking properties of cokes has been proposed (184). The use of radioactive tracers to determine the principal sources of sulfur in coke, such as pyritic, organic, and sulfate sulfur, has been reported by Eaton (88). It is concluded that pyritic and organic sulfur appear in coke in proportion to
ew of analytical methods for solid and ing some 212 references to sampling techand ultimate analyses, calorific value, ash, and such plastic behavior tests upon carbonization as the free-swelling index, expansion pressures, and agglutination properties, has recently been published by Gauger and Darby (106). A new sampling technique for coke, based on size and weight, has been suggested (126). German and Russian methods for the sampling and analysis of coal and coke, and their by-products, are described in a new book by Gluzman and Edel’man (108). See also (7). Further references to tests for specifio properties are noted in the paragraphs which follow. The use of the Brabender semiautomatic tester for the determination of moisture in coal has been described by Cooper et al. (80). An accelerated procedure for sulfur in coal and coke, involving coplbustion in a stream of oxygen, is the subject of a paper by Krolovets and c-workers (42). A study of coking and swelling properties of coking coals by semimicro exhaustive sold subsequent x-ray diffraction has appeared escribes an activated carbon procedure for the lefins in coke oven gas (5). Improvements in laboratory carbonization assay methods, in order more closely to approximate yields actually obtained a t the oven, to occupy the attention of investigators. ) concludes that the attainment of a rapid, acRichar curate still a long way off. New assay methods, said to approach more closely actual attained yields, have been reported by Tejnicky (,%&$), by Aronov (29), and by Simek (228). The latter investigator used a modified Fischer-Schrader retort. A crucible coking test applicable to a wide range of coking coals and cokes, including nonagglonierating coals, has also been devised by this worker (827). Naugle et al. (186) describe the design and operation of a small vertioal oven which yields coking pressures comparable t o both those obtained in large ovens of similar design and in sole-heated
1910
iNDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 41, No. 9
position as a first step, but hydrogenation, oxidation, hydrolysis, or some other unit process is subsequently also used in the over-all conversion process. GENERAL
An extensive compilation of the patent literature on oil shale and shale oil, covering the period up to 1945, has recently been issued by the United States Bureau of Mines (144). This review includes some 1000 Englishlanguage patents, and over 300 foreign-language patents on refining processes and products, with short abstracts of their subject matter, A book on oil shales and shale oils has also appeared (K?), the major portion of which is devoted to a description of mining processes and equipment for shale. Gardner (101, 106) and Ertl (91) have also disoussed the mining program of the Bureau of Mines oilshale project at Rifle, Colo. (101, I@), and Ertl (92) has described a hard-surfaced bit developed for use on western United States shales. Research progress on oil shale under the various Synthetic Fuels Acts, as i t is a t present being carried out by the Bureau of Mines, has been reviewed in detail by the Secretary of the Interior ($4). Included in this report is detailed information on the mining of the shale, its processing in the demonstration plant a t Rifle, and a discussion of research on various phases of oil shale work (retorting, thermal solution, kerogen composition, shale oil components, and by-products) now in progress a t the Petroleum and Oil Shale Experiment Station, Laramie, Wyu. Figure 1. Pilot Plant Oil Shale Retort, Union Oil Company, Wilmington, Calif. In a revim7 of the highlights of present day Russian chemical research containing some 189 references, Toplin (660) hm included some ovens. For further work on expandion pressures, see (150, late articles on oil shale pyrolysis. 166). Campbell (55) has classified the Xew Albany shales of midwestern United States according to their fossil remains. AnalTests for the measurement of coal strength are discussed in a yses of Ohio oil shale and its pyrolysis products have been repaper by Brown (61), who notes that variations are often due to ported by Kerr (142). Based on certain geologic principles of previous handling. A micromethod using a ball mill has been the formation of fresh water ponds and lakes, Bradley has offered devised by Koifman (146). New shatter tests to determine coke deductions on the nature and origin of the minerals and sediments strength are reported by a number of investigators (190, 241, of the oil shale deposits of the Green River formation (47). 846). Included is a rapid method (190) for determination of the A more accurate estimate of the oil resources of this region has cause of lowered strength, which makes use of the volatile matter been prwented by Belser ( ~ g ) who , states that the oil content of and ash content of the fines. The critical alr blast test has been at least 50% of this formation in Utah, and 90% of i t in Wyoming thoroughly examined by Kreulen (863, 224). A linear relation is still unknown. Preliminary figures on the cost of producing was found between coking temperature and test results. Fynthetic fuels from the United States oil shales are given by Heating values of coke obtained by the bomb oalorinietor are hfurphree ( 1 8 4 ) and others (88). The geology and chemical more accurate when the coke is first briquetted with 12% petroanalyses of the combustible shales of the Baltic have been noted leum coke, according to a recent paper (1,$'0), After having in a recent Russian book (16 7 ) . tested some 1200 samplcs of cod and 1200 samples of coke, A number of papers are concorned with the oil shale deposits Lefebvre claims ( 1 6 4 ) to have obtained formulas for calculation of specific countries throughout the world. Australian deof calorific values, based on humidity, ash, and volatile matter posits in Queenvland and Acland are examined by Ball (81). content; these are accurate to 35 calories in the range 7000 to A description of Australian shales and retorting methods at Glen 8000 calories per g r a m Davis is given by Cane (6~7). Pyrolysis tests on Canadian shale8 are tabulated by Ells et al. (89). Present-day activity in OIL SHALE PYROLYSIS the Scottish industry is mentioned (68). The deposits of the Grand Duchy of Luxembourg are the subject of two recent As stated in the previous review (198), the pyrolysis of shale accounts (9, 96). An analysis of three Swiss deposits has been has, up to the present time, been primarily directed toward the reported by Rickenbaugh ( d 0 6 ) , and others (89),and of the addirect recovery of petroleumlike hydrocarbons. This Is in conjoining Wurttemberg shale fields by Caldwell(63). Kern data on trast to coal pyrolysis, where metallurgical coke, gaseous fuels, the alum shale of Sweden have appeared (861)! as has information or fuel coke for conversion thereto are the major products sought. Synthesis of liquid fuels from coal may employ thermal decomon Polish (218)and Bulgarian oil shales ( 1SI). See also ( 4 9 ) .
September 1949
INDUSTRIAL A N D ENGINEERING CHEMISTRY
MECHANISM, KINETICS, THERMOCHEMISTRY
PRODUCTS AND BY-PRODUCTS
In a previous paper (60) Cane had concluded that torbanite is a progenitor of kerogen, and that the latter is a degraded polymer of unsaturated fatty acids-for example, eleostearic acidwhich underwent decarboxylation under pyrolytic conditions. As support for his theory he noted the close resemblance between the physical properties of certain plastic polymers and kerogen. In a recent paper the same author (68) applies this theory to the processes occurring when torbanite is pyrolyzed. Three stages are defmed: ( A ) formation of a rubberlike material showing swelling and other elastomeric properties; ( B ) production of a bitumenlike substance; and (C) cracking of substance ( B ) to shale oil. Although the detailed reconstruction of the molecular structure of kerogen on the basis of the above is too complex to be attempted, the author does give a general account of the mechanism of pyrolysis. Murphy and co-workers (186) have presented the results of a most worth-while study of the correlation between chemical structure of hydrocarbons and the physical properties-namely, pour point, viscosity, and density-of certain shale oil fractions. From their results they conclude that shale gas-oil may contain large percentages of fused ring compounds o€ a partially unsaturated character, with attached side chains.
The maior products and by-products of oil shale pyrolysis include shale oil, spent shale, shale gas, phenolic compounds, quinoline and pyridine derivatives, and thiophene homologs. Papers dealing with these are listed in the following paragraphs. a1 Services has issued a number of reports in recent years; most of these are concerned with data obtained by the I. G . Farbenindustrie on Estonian shale oil (239). Included are data on the production of aviation gasoline from these oils and accounts of experiments on the pyrolysis and hydrogenation of shales and shale concentrates a t around 800 atmospheres pressure. Details concerning plants for the hydrogenation and dehydrogenation of shale oil to produce fuels and the resulting analyses thereof, are given in an earlier compilation (199)of the same source. Liquid fuels from the Bureau of Mines program are discussed by Kraemer (169)and elsewhere (84, 168). The analysis of a Diesel fueI from a Russian shale-tar fraction is reported by Ershov (90). Contact desulfurization of a Russian shale oil gasoline in the vapor phase is described by Kazukov (198). Vian presents an account (263)of the subjection of a refined fuel fraction of shale oil to an 8000- to 9000-volt, 500-cycle current, with resultant threefold increase in its viscosity. Subsequent molecular distillation yielded fractions suitable for use as lubricants. Similar results of such a voltolysis treatment are given by Mora (189). The acid sludge from the treatment of an Australian cracked shale gasoline was found by Mapstone (177)t o contain pyridine homologs, cresylic acids, and small amounts of alcohols. The conversion of oil shale to Fischer-Tropsch synthesis gas, by partial combustion and steam addition is claimed in a recent patent (7.9). A similar process employing coke oven gas has been mentioned elsewhere in this review (816). An interesting me of spent Chattanooga shale for a decolorizing agent and in the manufacture of pigments of various sorts haa been noted (20).
RETORTS AND RETORTING PROCESSES
There have been many different designs of apparatus proposed for retorting oil shale in the past. An excellent summary of the patent literature on this subject is given by Klosky (14.4). A description of results obtained on the modified NTU retort now in use by the United States Bureau of Mines has been presented by Lankford and Guthrie (168), and others (94). The latter two references also make mention of several new pilot plant retorts now under investigation, including: a Jodavis flash carbonization retort employing Royster-stove heat exchange, which had previously been developed for low temperature carbonization of coal; and a gas-flow retort in whioh the shale is heated transversely across a downward-moving bed, by recycled hot shale gas. Reed and Berg (801) have designed a new retort in which ground shale is fed upward through a unit by a reciprocating piston, counterflow t o a downward moving stream of air (Figure 1). Heat is supplied by combustion of residual carbon on the shale clinker near the top of the retort. Pyrolysis products are withdrawn a t the bottom. A continuous process in which new and spent shale are mixed and fed to a rotary kiln, with or without addition of superheated steam, has also been patented by Berg (40). A further patent on the use of a fluidized bed for retorting oil shale has appeared (294). See also a Swediih patent (136) on a new retort design. The underground gasification of oil shale in situ and yields and products obtained a t Schorzingen have been reported in an earlier paper (81). THERMAL EXTRACTION c
1911
Thermal extraction of shale is in reality pyrolysis with accompanying simultaneous solution of organic matter. Chemical reaction with added reagents may concomitantly be caused to occur. I n this regard Brown has patented a process (60) in which 0.125-inch ground shale is mixed with a recycle vehicle oil and aluminum chloride, preheated to 250" C., and pumped to digesters held a t 200" C . Volatile products are removed from the digesters, the residual slurry is withdrawn, separated, and fractionated. Tests on Colorado shale, in which the oil shale is ground to 200mesh, suspended in tetralin, and subjected to hydrogen pressurea in the neighborhood of 200 atmospheres and temperatures of 400" C. and above have recently been described (19). AnaIyses of products and distribution of carbon, hydrogen, nitrogen, sulfur, and oxygen therein were determined.
ANALYSIS AND TESTING
BaIl and cbworkers (868)have investigated the nitrogen analysis of oiI shales md ehale oils by micro- and macro-Kjeldahl methods, and by the micro-Dumas method. By modifying the Kjeldahl macromethod and by correcting Dumas nitrogens by means of a mass spectrometer analysis of the nitrometer gas, agreement between these two procedures has been secured. Poor digestion obtained in the micro-Kjeldahl method is believed responsible for the erratic results herein obtained. The composition of mineral-free organic matter in oil shales, by division into fractions yielding percentages of ash both higher and lower than that of the original material, followed by extrapolation of the data to zero ash content, is claimed to be determinable from a method proposed by Himus (1.86). A procedure for total ammonia in sulfonated shale oil is presented by Reichert and Schwebs (902). The preparation and purification of sulfur compounds typical of those found in crude oils, including shale oil, have been begun by Haines et al. (119), together with the accumulation of data on their physical and thermodynamic properties.
ACKNOWLEDGMENT The author wishes to gratefully acknowledge the aid given by Francis Bonomo, Industrial Research Institute, University of Denver, in the collection of the numerous references on which this review is based and in checking the bibliographical citationa and manuscript.
LITERATURE CITED (1) Agroskin, A. A,, and Loskutova, E. N., Stal, 7,683-6(1947). (2) Agroskin, A. A,, and Petrenko, I. G., Bull. m d . a d . U.R.S.S., CZaaas mi. tech., 1948 (7), pp. 1116-26.
I N D U S T R I A L A N D E N G IN E E R I N G C H E M I S T R Y
1912
(3) Agrosky, A. A., Izuest. Akad. Nauk S.S.S.R., 1942, pp. 41-7. (4) Aktieselskabet Nordisk Gasvaerks Xompagni, Chimze & hdustrie, 57, 564 (1947). (5) Alekseev, N. F., Zavodskaya Lab., 13,1351-8 (1947). (6) American Foundry Association, Am. Fozindryman, 12, 49 (1947). (7) Anon., Brit. Coke Research Assoc., Tech. Paper No. 1 (1948). (8) Anon., Bull. Brit. Coal Utilisation Research Assoc., 12, 1-5 (1948). (9) Anon., Chem. A g e (London), 58, 199 (1948). (10) Anon., Chem. Eng. News, 26,632 (1948). (11) Anon., Coke, 10, 257 (1948). 112) Ibid., pp. 263-8. (13) Anon., Coke and Gas, 9, 255-60,266 (1947). (14) Anon., Colliew Guardian, 175, 629 (1947). (15) Anon., Echo des Mines et de la Metallurgic, No. 3388, 143 (1947). (16) Anon., Fortune, 37, No. 5, 110 (1948). (17) Anon., Genie cGiZ, 124, 396 (1947). (18) Anon., IND. ENG.CHEM.,40, 558-641 (1948). (19) Ibid., No. 12, p. 14A. (20) Ibid., p. 22A. (21) Anon.,Iron & Coal Trades Rev., 155, 1003 (1947). (22) Ibid.. 156, 307-17 (1948). (23) Anon., Koppers News, 19, No. 9 , s (1947). (24) Anon., U . S . Bur. Mines, Repts. Invest. 4457 (1949). (25) Anon., U . S. Dept. Commerce, OTS Re&, PBL 74642 (1938). (26) Zbid.,(1941). (27) Anon., World Petroletun, 18, No. 12, 80-1 (1947). (28) Zb$d., 19, NO.9, 49-51 (1948). (29) Aronov, S. G., and Eidelmon, A. Z - , Zavodskaya Lab., 13, 328.32 (1947) (30) Badger, E. H. XI., Chem. Age (London),59,447 (1948). (31) Ball, L. C., QueensZandGovt. Mining J . , 47, 176-9,311-12 (1946). (32) Bangham, H., and Franklin, R. E., TTans. Faraday Sac., 42B, 289-94 (1946) (33) Barlot,, J., Bull. sac. chim. France, 1947, pp. 892-3. (34) Beclrer, F. M., Proc. Conf. A m . Inst. Mining Met. Engrs., 6, 321 (1947). (35) Bec-key, H. E., U. S. Patent 2,438,199 (Mar. 23, 194s). (36) Bccker, J. (to Koppers Co., Inc.), Brit. Patent 602,474 (1948). (37) Beckei, 6 . (t,oKoppers Co., Inc.), U. S.Patent 2,447,837 (1948). (38) Boll, H. S.,“Oil Shales and Bhalc Oils,” Nem York, D, Van Nostrand Co., 1948. (39) Belser, C., Am. Inst. Mining Met. Engrs., Petroleum TechnoE. 11, No. 3 (1948) (Tech. Pub. 2358). (40) Berg, C. H. 0 . (to Union Oil Co. of California), U. S. Patent 2,441,386 (AIay 11, 1948). (41) Blayden, H. E., Gibson, J., and Riley, H. L., J . Chem. Soc., 1948, pp. 1693-1700. (42) Bondarenko, M. hl., Krolovets, 6. M., and Belyaeva, A. P., Zavodslcaya Lab., 14, 991-2 (1948). (43) Boon, W. 11..H.M. Stationery Office, London, Proc. Fuel and Future Conf., 2, 366-8 (1948). (44) Booth, N., et al., Gas World, 128. 588-9, 686-92 (1948). (45) Booth, N., and Jolley, L. J., Gas Research Board, Copyright Pub. GRB 22, Ififnrm. Ciic. No. 2, 3-28 (1946). (46) Bradley, G. W. J., et al., 1I.M. Stationery Office, London, Proc. Fuel and Future Con!., 2,222-5 (1948). (47) Bradley, W.H., Bull. Geol. Sac. Am., 59,635-48 (1948). (48) Brewer, R. E., et al., IND.EXG.CHEW,40, 1243-54 (1948). (49) Brockamp, E., et al., Arch. Lagerstlittenforsch, 77, 1-59 (1944). (50) Brown, €1. D., U. S. Patent 2,431,677 (Dec. 2, 1947). (51) Brown, R. L., F,neZ, 27, No. 3, 82-95-(1948). (52) Brown, T. W., Gas World, 128, No. 3316, Coking Set,, 30 (1948). (53) Caldwell, J. M.,and Smith, C. H., H.M. Stationery Office. London, BIOS Item No. 30, Final Hept. No. 1221 (1947). (54) Campardou, J., Bull. soc. chim. France, 1948, pp. 532-3. (55) Campbell, G., Bull. Geo?. Sac. Am., 57, 829-908 (1946). (56) Campbell, R. W., Proc. Conf. Am. Inst. Mining X e t . Engrs., 6, 23-37 (1947). (57) Candea, C., Sauciuc, L., rind Fridlovsohi, A., Bull. Inst. Null. Cercetari Tehmol., 2, 72-80 (1947). (68) Cane, R. F., Australian Chem. Inst. J . & Pvoc., 15, 62-8 (1948). (59) Cane, R. F., J . Inst. Automobile & Aero. Engr., 7, N o . 9 , 1 3 5 4 0 (1947). (60) Cane, R. F. J . 9oc. Chem. 2nd. (Eondcm), 65, 412 (1946). (61) Carabasse, J., Chimie & industrie, 58, 228 (1947). (62) Carnegie-Illinois Steel Corp., Brit. Patent 606,112 (Bug. 6. 1948). (63) Cassan, H., Chaleur & Ind., 29,292-8 (1948). (64) Cassan, H., Gas J., 253, 151 (1948). (65) Cassan, H., Gas World, 127, 737 (1947). (66) Chapman, M.E., Ibid., 130, 106-11 (1949). ~
Vol. 41, No. 9
(67) Chizhevskii, N. P., and Chernyshev, D. M., Izvest. Akad. ~Vauk S.S.S.R., Otdel. Tekh. h’auk, 1948, pp. 23-7. (68) Chow, C. S., Proc. Roy. Soc. (London),A192,340-64 (1948) (69) Christiansson, B., Iva, 17, 221 (1946). (70) Ibid., 18, 89 (1947). (71) Ibid., pp. 106-14, 166-78. (72) Chriutiansson, B., Teichert, W., and Bengtson, E., Ing. Veten,. skaps Akad., Peat Lab. Communication hT0.2, (1948). (73) Clark, A. (t’o Phillips Petroleum Co.), U. S. Patent 2,452,684 (Nov. 2, 1948). (74) Clark, A. A,, and Sowden, W., Coke Oven Managerss Assoc. Yearbook, 1947, pp. 201-18. (75) Clendenin, J. D., et al., Pmn. State Coll., Mineral I n d s ~Expi. Sta., Tech. Paper 108 (1945). (76) Clendenin, J. D., and Kohlberg, J., Ibid., 136 (1948). (77) Clyzewski, M. and Gossyk, O., Hutnik, 14, 131-9, 193-239 (1947). (78) Cooke, J. O., and H u t t , A. C., Fue2 Econ. Rev., 26, 41-5 (1947j (79) Cooper, C., and Henshaw, 0. M., Inst. Gas En,grs., Commur; No. 335 (1948). (80) Cooper, H. M.,Tarpley, E. 6., and Abernethy, R . F., Va $3 Bur. Mines,Repts. Invest. 4304 (1948). (SI) Curtis, A. L., Chem. Age (London),57, 570 (1947). 182) Das, R. K., J . Sei. Ind. Research (Indin), 6B ( l l ) , Iti? b (1948). (83) Davis, J. D., Am. Gas Assoc., Proc., 29, 87-98 (1947). (84) Davis, J. D., at al., U . S. Bur. Mines, Tech. Paper 702 (1947j (85) Davis, J. D., and Reynolds, D. A.? Am. Gas Assoc., Proc.. 28 4 2 6 4 1 (1946). (86) Delassucs, M.,and Devaux, R , , Chalew d Ind., 28, 209 (1947’ (87) Duchene, G.,Ibid., 29, 113-25 (1948). (88) Eaton, S. E., Hyde, EL. W., and Old, B. S., A m . Inst. M
