US2453543A - Process of treating bituminous coal - Google Patents

Description

Nov. 9, 1948.

PROCESS OF TREATING BITUMINOUS COAL E. J. SCHABELITZ Filed April 9, 1948 COKING.)

COAL

DRAIN AND/OR I PASS COAL THROUGH E CENTRIFUGE COAL DICHLORIDE I SEPARATE COAL FROM SOLUTIONEJ THYLENE RECOVER ETHYLENE DICHLORIDE SOLUTION OF RESINS, ETC.

DISTIL AT DRIER AT ABOUT 220F COKE THE TREATED COAL RECOVER COKE RECOVER BY- PRODUCTS ABOUT I85F CON DEN SE ETHYL ENE DICHLORI D FRACTIONATE IF REQUIRED I COKING RECOVER FRACTIONATED BY- PRODUCT HAX-RESI 0| 'BOTTOMSI ETHYLENE RESINOUS PRODUCTS QB DISSOLVE ONE PART BY wT. DICHLORIDE FOR PAINTS. ETC. RESWOUS BOTTOMS |N ONE STORAGE PART ETHYLENE QI L Q FL E ETHYL ADD TWO PARTS ANTI- ALCOHOL SOLVENT I ETHYL ALCOHOL) STORAGE PRECIPITATING RESINS.

RESIN PRECIPITATE SQLUTION FRACTIONALLY OR RE m lsm PRODUCT DISTIL OFF FRACTIONAL LY SOLVENTS 0 ISTIL SOLVENTS OILS AND WAXES FRACTIONALLY msm .[VI/E/VTOR 8x #1: A Tron/vars Mink/q M50, F0575? cffihnms Potented Nov. 9, 1948 UNITED STATES PATENT OFFICE 2,458,543 PROCESS OF TREATING BITUMINOUS COAL Ernest J. Sehsbelitn, Eineon, Calif.

lmllcltlon April 9.

1948. Serial No. 20.099

8 Claims. (Cl. ZBfi-IW) as commercial fuels for home furnace use and the like.

Heretofore attempts have been made to treat coking plants employing conventional coking coal. In view of the last indicated a general object of my inventour for coking purposes, tion 01 good metallurgical This application my earlier application Serial September 26, 1948.

The accompanying drawing, nature or a is a continuation-in-part of No. 999,591, illed volatile materials such as resins. waxes. oils and similar constituents which render the coals suhstantialiy non-cokablc, that is. coals oi the described Utah type, may be rendered cokable by extraction with eth'y the extraction being pheric temperatures and pre of the coals in the lene dichloride as a solvent,

carried on under atmosssures by immersion ethylene dichloride for a moderately brief interval of time twenty minutes and about one lies between about hou so that suiiicient similar materials are extracted products cokable,

ment which would possibly others of but which ordinarily of resins, waxes. oils and to render the coal without any over-treatresult in removal of tars and the less soluble materials apparently necessary ior proper coking operations.

Such over-extraction deleteriously aiiects the if these non-cokab ethylene dichloride example ten hours or more at tures, especially at peratures of around 7 neighborhood of 100 tars and possibly which apparently render t undesirable are deleteriously operations of covery systems at lay-products desire Thus,

processes heretofore to extract the coal period of time with or wit to remove as many of the possible, elevated this invention is d known where it with a solvent for a long average other less e upset and d are n tempera boiling point of the solvents or if required to effect max extraction. According to the however, the extraction is carried optimum to produce the best e yield coking by-products best approximating he treated coal because its coking characteristics affected, and al imum or present invention,

By the to indicate that, m

extracted with normal temperaatmospheric tem- 0 1'. to summer heat in the R, such extraction removes soluble materials product so because the the well established by-products rethe conventional ot obtained.

istingulshed from was sought so hout further extraction soluble constituents as tures approaching the above being used as other extensive on only to the oking coal and to conventional by-products recovered from ordi nary coking coals well known in the industry.

Considering the treatment bituminous coals,

mine coal without grinding or powdering operation, leached in a quantity of ethylene dichloride,

is, the coal is placed in quantity sufllcient unheated,

peratures such as the above to cover are they r being put through a special of the described described run of is immersed and that ethylene dichloride in the coal. Both the coal and the ethylene dichloride are preferably that is, in no instance, in accordance with this invention, nary normal tempera aised above orditures or summer heat temaround 70' F. to 110 F. For

atmospheric temperatures, and

carried on at atmospheri -the temperature is aroun temperature of 60 and the solvent are If the temperature. ing, the process is prevailing atmospheric results have still usually 15' 1 the immersion period minutes.

be used for the coal and the solvent were at a on simply at c pressures. d the average normal 1'., or 80 F., the coal both employed at such a temperature drops to freez- However, the ethylene could have a somewhat greater temperature, that is, anywhere up to any other ordinary cated, such as summe solvent.

operations ordithe prevailing they are likewise Thus, if

carried on at the temperature. Excellent been accomplished, for example, where the atmospheric temperature was about being only sixty dichloride might storage where it perhaps 60 F. or 70 F., but

temperature as above indir heat temperature, might Possibly, if both the low temperature. n

fore avoid producing extracted coal of objectionable coking properties.

From the standpoint of operations at normal temperatures, as above indicated. another very important factor is the convenience of operating at atmospheric pressure. While it is within the scope of this invention to employ elevated pressures if desired, no important advantage is obtained, and if elevated pressures are employed the economy of operating at atmospheric pressures is lost. Similarly, if desired to keep the ethylene dichloride at average normal temperatures, for example, between about 60 F. and about F., when the atmospheric temperature is lower, as when it is around freezing or lower, the solvent may be correspondingly warmed, but again the economy of operating at the existing atmospheric temperature is lost,

Various ramifications of the process within the limits above indicated may be employed accordingly as operating conditions may indicate to be desirable. For example, batch operation enacted by soaking the coal in an adequate amount of ethylene dichloride sumcient at least to immerse the coal may be employed, the soaking continuing for the required time interval as above indicated, with recycling of the solution if desired. Again, the operation may be continuous, and this probably will be most economical in nearly all installations, especially large installations. If desired, for any particular purpose, combinations of batch and continuous operation may be used. In the case or continuous operation, the coal may be passed by mechanical conveyors from one end of a long tank to another at such a rate as to provide the required extrac tion. In such a case the ethylene dichloride solvent itself may be supplied in batches, coal being passed therethrough until any desired concontration of extracted resins, waxes, oils and other soluble constituents of the coal is attained, whereupon a fresh batch of the solvent will be introduced after running oi! the "rich" solution. In any event, the treated coal preferably is given a final rinse with fresh or "lean" ethylene dichloride. 0n the other hand. when mechanical conveyors are employed for moving the coal through an elongated tank, fresh or "lean" ethylene dichloride may, if preferred, be continuously introduced at the discharge end of the tank, and the rich ethylene dichloride solution withdrawn from the coal-feed end of the tank, the rate of introduction and withdrawal of the ethylene dichloride and the coal being proportioned to the amount of coal being passed through the ethylene dichloride so that the desired concentration of extracted material is reached at the time of withdrawal. As will be apparent to those skilled in the extraction art, the solution would not be permitted to become so concentrated as to produce unsatisfactory extraction.

From the standpoint of the size or the coal being treated. this ordinarily will be run of mine coal, that is, coal as mined, without. however, excessively large lumps. as previously indicated. In no instance should all the coal be crushed or ground to a powder. Thus, while run of mine coal will commonly contain a considerable portion which may run as fine as one hundred mesh or finer. although such proportion does not deleteriously afiect coking, nevertheless. if all of the coal were to be reduced to such a degree of fineness, the treated product would not coke properly. It is necessary and desirable that a considerable proportion of the coal be of appreciably larger sizes, such as about one inch size to three inch size. or larger, or too large to pass a onehalf inch screen. Moreover, a considerable proportion of the coal may be of still larger sizes. and coal has been successfully treated where lumps were present running up to seven inches in their smallest or transverse dimension, or. in other words. coal passing a seven or eight inch screen. As previously defined, the terms "run oi mine" and "coal as mined," as used herein, are intended to indicate a coal of ordinary run of mine characteristics in which there are not many large lumps in excess of about seven inches in transverse dimension. Preferably, any such larger lumps should be broken into pieces ranging in the order of one inch to four or five inches. or up to about seven inches in transverse dimenslons so that all of the coal may be within sizes that may be classed within the above run of mine definition. Powdered cool. that is. coal in the order of one hundred mesh and finer tends toward over-extraction which is apparently of!- set to some extent by more limited removal of some of the (less soluble) constituents in the larger sizes. for example those running between about two inches and seven inches in their transverse dimensions. As a consequence, treatment of run of mine coal with ethylene dichloride at atmospheric temperatures and pressures as above defined, and within treating times of about fifteen minutes to not over about one hour and onehalf, produces good coking coals from non-cokable bituminous coals or the Utah type herein described.

In general. the longer times between about an hour and one and one-half hours are employed where treating coals at temperatures below freezing. and the shorter periods, for example twenty minutes, have been found satisfactory where treating under summer heats. for example around 90 F. to 100 F. However, should any particular run of mine coal tend to run in the larger sizes rather than in the smaller sizes it may. at least for some coals. be preferable to use the longer treating time, that is, around one hour to as much as about one and one-half hours, even though operating in the upper portion of the indicated temperature me.

When the treated coal is to be removed from the solution oi the extracts in ethylene dichloride, as much of the ethylene dichloride solution is removed as possible by any convenient operation. Thus, if a strictly batch treatment is employed, and the solution is drained from the coal, an adequate time will be allowed for drainage of the solution out of the tank and, if desired, auxiliary means, such as blowing. may be employed.

Such blowing ma include hot air blowing for the purpose of further removal, as by volatilization. of the ethylene dichloride. Where the coal oeing treated is carried through the ethylene dichloride bath by mechanical conveyors, whether by counter-current fiow of ethylene dichloride or otherwise, the coal will be allowed to drain adequately and may then be passed to centrifuges for removal of all excess liquid ethylene dichloride possible, the coal being then passed through steam heated units ior volatilization oi the remaining ethylene dichloride. Buch units may be heated. for example. to the boiling point of ethylene dichloride, namely, about F., or somewhat above that temperature, for example. around 200 F. to 212 F. The hot. dried coal is then passed as desired through cooling means, or otherwise. to tlpple screens or to cars or other transportation means, or to stock piles.

The ethylene dichloride evaporated from the coal, as indicated, is recovered by condensation for further use. Upon drying of the coal or its ethylene dichloride content, the surface of the coal particles is found to be covered with an almost infinitesimally thin layer of the resinous and waxy materials extracted from the coal particles and pieces, which layer acts to reduce dust formation and also reduces the hazard of spontaneous combustion of the coal.

The ethylene dichloride solution removed from the coal by drainage, by centrifuging or by removal from the coal-feed end 01' the treating tanks. and, therefore, containing constituents extracted from the coal, may be passed to an appropriate still heated to appropriate temperatures such as from about 185 F. to about F., in order that the ethylene dichloride may be recovered and reused.

However, the ethylene dichloride solution sometimes contains extracted fractions from the coal whose distillation temperatures are so close to the distillation temperature of ethylene dichloride at atmospheric pressure that, when desired to recover these fractions, fractional distillation may be employed. Such distillation may be effected at the time of removal of the solvent from the resins and other residueJorming materials. or the solvent including the desired low boiling extracted fractions may be first distilled of! from the resins and other residue-forming materials, and then fractionated.

The ethylene dichloride distilled from the extracted fractions represented by the resins and other extracted materials is recovered by condensation for further use in treating fresh coal.

The resinous residues recovered upon removal of the ethylene dichloride are in a solid to a semi-solid condition and may be used without further treatment in the preparation oi paints or varnishes, or in connection with the plastic industries, or for any other purposes to which resinous and waxy materials are adaptable, or, they may be further refined or decolorized for appropriate uses. Alternatively, these resinous bottoms may be fractionated into their various constituents for various purposes. The first separation stage may be eii'ected at atmospheric temperatures and pressures by selective solvent extraction and precipitation. Thus. according to one method of separation. one part by weight of the resinous bottoms recovered upon distilling oi! the ethylene dichloride, is dissolved in one part by weight of lean ethylene dichloride. and two parts by weight of 95% ethyl alcohol, or denatured ethyl alcohol, are added to the ethylene dichloride solution, whereupon certain of the resins are precipitated out. In another method of separation the ethylene dichloride is distilled until the still bottoms contain approximately 50% of ethylene dichloride (approximately 1.86 specific 7 gravity at 60 R). Then about two parts by weight of denatured alcohol are added for each part of ethylene dichloride by weight. Other anti-solvents such as methyl alcohol. propyi alcohol and iso-propyi alcohol may be substituted for the above mentioned alcohol.

After precipitation has been completed, the precipitated resins and associated materials are settled and separately recovered. The precipitate may then be used as a resinous product for paints and varnishes and other purposes as above indicated. or otherwise, or it may be fractionated by heat, that is, fractionally distilled.

The supernatant liquid separated from the precipitate produced by the addition of ethyl or other alcohol as above described. is then distilled to remove the ethylene dichloride solvent and the alcohol. their separation being fractional. Separated lean ethylene dichloride may then be passed to storage with the other recovered ethylene dichloride separated from the treated coal, and the alcohol returned to storage to be used for further precipitation of resins.

The bottoms remaining following removal of the ethylene dichloride and the ethyl alcohol are oils and waxes, and they may be further separated into fractions by vacuum distillation.

In general, the resinous, waxy, oily and similar materials recovered from bituminous coals of the stated Utah type commonly run from around sixty-five pounds to one hundred pounds or more per ton, the greater proportion of this extract being precipitable with ethyl alcohol from ethylene dichloride solution as above described.

The treated coal dried as above described presents a shiny appearance resulting apparently from a very thin film of resinous material with which the surface of the coal is coated after the ethylene dichloride has been dried out and thus freed from the coal. By reason of the treatment of the coal and the presence of this thin film of resinous material the tendency of the coal to form dust is almost entirely eliminated. As a consequence of this non-dusting property and the removal of the soluble extracts by the ethylene dichloride. it becomes a very valuable fuel for use in home furnaces and for similar purposes. However, its greatest value lies perhaps in its usefulness for coking, especially since it produces good metallurgical coke. The improvement of the coal both from a coking standpoint and as a fuel is in part represented by the marked increase in B. t. u.'s per pound, which increase for different coals runs from about 300 B. t. u.s per pound to about 900 B. t. u.s per pound. For example, in one particular instance the B. t. u. rating per pound was increased from about 12,809 for the untreated coal to 13,700 for the treated coal. In this latter instance, the fixed carbon content was correspondingly increased from 48.4% to 49.6%. At the same time, the volatile matter content, the ash content, and the sulfur content were all reduced. The improvement in the coal for both domestic fuel purposes and coking purposes is further illustrated by the actual loss in weight of the coal due to the removal of the valuable by-products, which if left in the coal are objectionable and. moreover, are wasted in burning.

Where the treated coal is to be used for coking, it is fed to a conventional coking furnace in a conventional manner and coked in a conventional manner. The by-products of the coking operation are passed to and treated in any standard or conventional lay-products apparatus for the separation and recovery of the usual byproducts from coking plants. Such treatment is entirely feasible because the specific extraction process of the present invention yield for coking purposes a coal which does not upset the usual operation of the coking plant and its by-products recovery unit.

Oraall'rrou Exmsks As examples of operation according to this invention, run of mine coal from the Deer Creek coal field in Utah and from the Geneva Steel coal fields in Utah, which coals are bituminous coals of fairly high resin content, were employed.

These coals contained no lumps larger than about six inches in their shorter or transverse dimension. As has been previously indicated. the term "run of mine coal" is intended to signify a coal which has no lumps larger than about seven inches in transverse dimension, and, if any appreciable portion of larger lumps is encountered, it is preferable to break or remove these lumps. For complete uniformity of treatment it might sometimes be deemed desirable that there be no lumps larger than three or four inches in greatest dimension, but as has been previously shown, this is not necessary to produce a coal having entirely satisfactory coking qualities.

Where batch treatment is employed, the coal may be immersed in ethylene dichloride contained in an appropriate tank. The amount of ethylene dichloride should be sufilcient to cover all of the coal being treated.

In a specific instance, using coal from the Deer Creek field in Utah. immersion of the coal at about 70 F. in ethylene dichloride at a temperature of about 70 F. was maintained for about forty minutes, whereupon the ethylene dichloride solution was drained off and passed to another tank for similar immersion of another batch of coal. Several similar quantities of coal were treated with the same ethylene dichloride solution. Commonly such treatment is continued until the ethylene dichloride contains from about 20% to about 35% of resinous. waxy, oily and similar materials extracted from the coal.

As another example of extracting bituminous coals of the Utah type, a quantity of coal from the Geneva Steel coal field of Utah was placed in a tank and submerged in ethylene dichloride which was continuously recirculated by drawing from the bottom and returning at the top. Here,

the operating temperature ranged between about 15 F. and about 20 It, and the treatment was continued for approximately sixty minutes. The solution was then drawn oil, and the coal given a brief rinse with lean ethylene dichloride to wash off excess resinous material on the surface of the coal.

In each instance, the treated coal, which possessed a shiny appearance due to a very thin coating of resinous material remaining upon the surface of the particles, was passed to a standard coking plant and coked. The coke was found to possess the conventional characteristics for metallurgical coke, and the by-products of the coking operation were found to be successfully treated in the usual by-products recovery unit of the coking plant without upsetting the economics of the system or the operation of the system. No substantial distinction over the usual coking coal was found, either in the coking qualities or in the by-products production of the various coals treated as above described. These various cokes successfully withstood the usual sieve test, tumbler test and shatter test. These statements apply as well to coal containing seven inch lumps as to coals which have been reduced to sizes containing lumps not over about two inches.

For the purposes of this invention, all extraction requirements with the ethylene dichloride are met when extracting within the above stated time and temperature ranges at atmospheric pressures, this being the result of the unexpected discovery that ethylene dichloride is the only solvent satisfactory for these purposes and conditions.

As a specific example showing the beneficial eiiects of my process. the following test data are furnished for Deer Creek coal treated by the batch process as above described. It will be observed that these data show in the treated coal a reduction in the volatile matter, the ash, and the sulfur content, together with an increase in the fixed carbon content and in the B. t. u. value. These data also indicate the coke yield and the coke by-products together with the yield the coke by-products.

Urarr Br'mmnoos COALDII:R CREEK Frau) Untreated Volatile 43.56%; ash 7.30%; sulfur 1.16%; fixed carbon 48.40%. B. t. u./lb. 12,831.

Leach with ethylene dichloride Ethylene dichloride solution.

Treated coal:

Volatile 42.67%; ash 6.06%: sulfur 1.01%;

fixed carbon 49.60%; B. t. u./lb. 13,721.

Coke yield 63.55%

Ash 10.24%; volatile 3.67%: 88.09%; suli'ur .83%.

Coke lay-products Gas 10,991 cu. ft. total per ton of coal fixed carbon Ethylene dichloride solution distilled at 185 F.

Resin and oil residue66.1 lb./ton coal=3.3%. Dissolve in equal weight ethylene dichloride; add 2 parts by weight 95% ethyl alcohol to precipitate resin.

Decent Precipitate Alcohol Solution Fractionally distil. Remove alcohol and ethylene dichloride.

Frectionally distil residue.

Variations oi the generic invention herein disclosed doubtless will occur to others skilled in the art. and it is intended to protect all such modifications as fall within the scope of the claims.

I claim as my invention: p

1. A process comprising: leaching bituminous poorly cokable coal 0! the type containing resinous and other soluble constituents which render the coal poorly cokable. the leaching being per formed by immersing the coal in ethylene dichloride under atmospheric temperature and pressure ranges for a brief period 01 time between about one-quarter of an hour and one and one-half hours to remove Irom the coal resinous and other ethylene-dichloride-soluble materials to Yield a coal having good coking properties; separating the treated coal from the ethylene dichloride solution to recover the resultant cokable coal; and recovering from the solution the resinous and other constituents oi the coal dissolved therein,

2. A process as in claim 1 wherein the leaching step is carried on at temperatures between about 60 F. and about F. and for a period of time between about fifteen minutes and about fifty minutes.

3. A process as in claim 1 wherein the leaching step is carried on between about 15 F. and about F. for a period or time approximating fifteen minutes to one and one-half hours.

4. A process as in claim 1 wherein the leaching step is carried on below about 32 F, for a period of time between about fiity minutes and about one and one-half hours.

5. A process as in claim 1 wherein the leaching step is carried on at summer heat temperatures for a period of time approximating twenty minutes.

8. A process comprising: leaching a bituminous non-cokable coal of the Utah type containing resinous and other soluble constituents which render the coal non-cokable for metallurgical P rposes, the leaching being performed by immersing the coal in ethylene dichloride at approximately atmospheric temperatures and pressures for a brief time approximating forty to sixty minutes to remove from the coal resinous and other ethylene-dichloride-soluble materials, to yield a coal having good coking properties; separating the treated coal from the ethylene dichloride solution to recover the resultant cokable coal; and recovering from the solution the resinous, waxy, oily and other materials dissolved therein.

'7. A process comprising: leaching a bituminous poorly cokable coal containing resinous and other soluble constituents which render the coal poorly cokable, the leaching being performed by immersing the coal in ethylene dichloride within atmospheric temperature ranges between summer heat temperatures and winter temperatures below freezing approximating 15 F. for a time between about fifteen minutes and about one and one-half hours to remove from the coal resinous and other materials soluble in ethylene di chloride to yield a coal having good coking properties; separating the resultant ethylene dichloride solution from the treated coal: recovering in solution in ethylene dichloride the materials dissolved from the coal; and separating the dissolved materials from such solution.

8. A method comprising: leaching a bituminous poorly cokable coal 0! the Utah type containing resinous and other soluble constituents which render the coal poorly colrable, the leaching being performed by immersing the coal in unheated ethylene dichloride at atmospheric temperatures and pressures for a brief time ap- I! proximetmftwenty minutes to remove iron: the ace! reeinoue and other ethylene-diohloride-eoluhle metemle to yield a coil hevinl lood ookin properties: eepereting the treated coal from the ethylene dichloride solution to recover the re- Iuitent cobble coll: end recovering Irom the eolution the resinous and other meteriele dieeolved therein.

ERNEST J. scmnnm.

. e human-Nous crmn I "I'he following references are of record In the file ofthis potent:

Nezelvoort. "Chemical and Metellurcicel Engineerlnl. Oct., 1942, men 80-82.

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