US2752293A - Process for carbonizing coals having a high volatile matter content - Google Patents

Description

June 26, 1956 E. M. BURsTLElN 2,752,293

PRocEss FOR cARBoNTzING coALs HAVING A HIGH voLATILE MATTER CONTENT Filed Oct. 28, 1950 2 Sheets-Sheet l Ifgfz Dalen/NN June 26, 1956 Filed Oct. 28, 1950 E. PROCESS FOR C Eye.

A dem! dO/vqLo/v/Eennf com M. BURSTLEIN ARBONIZING GOALS HAVING A HIGH VOLATILE MATTER CONTENT 2 Sheets-Sheet 2 PROCESS FOR CARBONIZ'ING COALS HAVING A HIGH VOLATILE MATTER CONTENT Eugne M. Burstlein, Thionville, Moselle, France, assignor of one-half to Societe des Acieries de Longwy (Societe Anonyme), Paris, France, a company of France Application October 28, 1950, Serial No. 192,678 Claims priority, application France November 14, 1949 4 Claims. (Cl. 202-25) The present invention relates to the production of high temperature, metallurgical coke from non-caking coals, i. e., coals having a low ability to soften and a high percentage of volatile matter. Such coals are generally considered as unsuitable for coke production.

As known, the coking properties of coal are determined by its constituents. Durain is an unsoftenable constituent of high volatile content, whereas vitrain is a constituent which imparts coking properties to the coal. Hence a coal will be said to be a good coking coal, when its vitrain content is relatively high. On the contrary, it will be a non-coking or badly coking coal if the proportion of vitrain is relatively low. Other constituents of coal are fusain which is also unsoftenable but which has alow volatile content, and clarain which has properties similar to those of vitrain.

This invention has for its object to provide a process for producing metallurgical coke from non-coking or badly coking coals.

To this end, such coals, in the form of particles, are mechanically graded, in order to separate the relatively large durain particles from the other constituents. This durain, after being purified to eliminate therefrom sedimental mineral constituents such as tailings and middlings is subjected to low temperature distillation to convert it to semi-coke. It is then ground to reduce its granulometric size, and then mixed with the other constituents. The whole mixture is then subjected to high temperature distillation, in a conventional way, i. e., in a closed chamber, at a temperature above 1000 C.

Owing to the low volatile content of fusain which has also a low ability to soften, it is not of interest either to predistill it or to eliminate it. Because of its finely divided state, it constitutes, on the other hand, a perfect impoverishing product. However when it contains too much mineral matter, its elimination may be required since the demineralization processes by electrostatical purification or flotation, are not usually satisfactory, in this case. When the fusain is eliminated, it is obviously necessary to increase, in the reconstituted coal, the percentage of predistilled durain.

By the above mentioned steps, the volatile matter content of the reconstituted coal prepared for carbonisation is sufficiently lowered, for achieving carbonisation without undue cracking of the coke; its softening qualities are increased because the easily softening constituents, such as vitrain and clarain, remain unchanged whilst the mass of those substances having no or only low softening qualities is reduced by reason of the elimination of mineral matter and of the reduction in weight of durain by predistillation and their ash, sulphur and phosphoruscontents are decreased as a result of the elimination of mineral matter. A pure and well softened coke having little cracks is thus obtained.

Other objects and advantages of the invention will be apparent during the course of the following description. In the accompanying drawing forming a part of this apnited States Patent rice plicaton and in which like numerals are employed to designate like parts throughout the same, Y

Figs. 1 and 2 are diagrams of plants for carrying out the process.

The plant of Fig. 1 is designed for the treatment of coal having a high percentage of volatile matter and whose fusain does not contain excess of mineral matter. The raw coal to be coked is supplied at A and it lirst undergoes on T1 a primary size grading in order to remove therefrom the primary durain preexisting in the free state. This operation is carried out by merely screening through sieves ai and b1 equipped with different meshes. The mesh size of the sieves ai and b1 is determined so that a primary concentrate of fusain, vitrain and clarain is collected in the lowest graded fraction, i. e; in the screenings, and a primary concentrate of durain lin the intermediate graded fraction, the upper graded fraction, i. e. the oversize of the sieves, being formed of coal in the conglomerate state. v

Primary durain often appears with a prevailing granulometric size of about 2 to 4 millimetres, whereas the grains of fusain, vitrain and clarain usually lie below 2 mms. When coal is dry, itis possible to resort to any type of sieve; on the contrary when coal is wet, it is convenient to use uncloggable sieves.

The primary concentrate of vitrain, clarain and fusainA is led to the silo vcf, the primary concentrate of durain undergoes purification in the purifier E in order to free it from tailings and middlings, and the concentrate of conglomerate undergoes disintegration in a crusher or disintegrater D in order to liberate its various constituents.

The disintegration of the conglomerate is effected either by mild grinding and recycling any unground product, or better still by controlled disintegration in an apparatus throwing with an appropriate velocity the various pieces of conglomerate against a hard surface to submit said pieces to impacts.

The disintegrated products next undergoes on T2 a secondary size grading for the purpose of extracting therefrom secondary durain. The operation is carried out on vibrating sieves a2 and b2 equipped with different meshes properly chosenaccording to the size of the secondary grains of durain. Thus the fraction passing through sieve b2 consisting of a concentrate of vitrain, fusain and clarain, is led tovsilo vcf, whereas a secondary concentrate of durain is collected between the sieves b2' and az and sent to purification, the oversize of tray a2 which constitutes a secondary concentrate of conglomerate, is sent,

back for disintegration in D.

The primary and secondary concentrates of durain are l5'- i directed separatelyl or admixed to purification at The' sedimental mineral constituents have effectively a 'tendency tol concentrate in the same graded fraction as durain, owing to their hardness. Any purification process may be resorted to, but it is usually more convenient to use pneumatic boards whose operation is less costly and which yield very good results, of the products fed to the purifier there is only small variations of granular size, the washing or gradingcurves of said products having been 4screening and disintegration.

In the purification plant, there is usually obtained three classes of products: tailings which areA sent to the s'ilo s, middlings which are led to silo m, and a concentrate of purified durain which' is directed to the predistillation plant C.

Predistillation is greatly facilitated owingto the fact that. the concentrateof durain appears as a `perfectly graded product lying within a narrow range of size, so that all the grains having substantially the same size are similarly coked. Thus under-coking and over-coking are avoided. Predistillaton may be carried out in any type of oven Patented June 26, 1956 because between the grains substantially improved -by whether rotating or vibrating. However as the durain extractedl from coals having a high percentage of volatile matter, has relatively low softening qualities, a quick heating oven is conveniently used. The semi-distillation plant C operates in a conventional manner for producing semi-coke, i. e., at a temperature of about 500 to 600 C.

The semi-coke of durain discharged from `C is next sent to the grinder Brwhich gives it an appropriate granular size of the magnitude of l milllimetre.

The ground semi-coke of durain is then led to the silo d.

The initial coal has finally given rise to four products:

Tailings collected in sand cast away,

Middlings collected in m and which can be sent to the boilers,

A concentrate of vitrain, clarain and fusain, stored in ref and intended for carbonisation,

Semi-coke of durain storedy in d and also intended for carbonisaton.

These last two groups of products are proportioned at the outlet of their storing silos and forwarded to the coke ovens F through a mixer M.

In order to adapt the output of semi-coke to requirements, it is sufcient to alter the mesh of the ganzes of sieves b1 or b2.

Fig. 2 is a diagram of a plant for carrying out the process in the Icase of coal having a high percentage of volatile matter whose fusain has an ash content too high for contemplating its use as an impoverishing substance. Under these conditions, instead of merely extracting durain and mineral matter -concentrated therewith, it is convenient to separate the coal completely into its petrographic constituents accordingv to the process described in my eopending U. S. patent application Serial No. 119, 618, tiled October 5, 1949.

It Awill then be possible to withdraw from carbonisation all or part of the concentrate of fusain, and this eliminated fusain will be replaced by a certain amount of semi-coke of durain whose output will be increased by decreasing the mesh of sieves b1 or b2. It is of course possible to substitute, for the eliminated fusain, other impoverishing products such as coke dust or anthracites.

The diagram of Fig. 2 is different from that of Fig. l in so far as sieves c1 and d1 are added to those of theI primary size grading apparatus T1 and sieves c2 and d2 to `those of `the secondary size grading apparatus T2. Vitrain, clarain and fusain (which have passed through the sieves b1 and b2) are thus separated into concentrates of fusain (passing through the sieves d1 and dz), and concentrates of vitrain and clarain (over-size of sieves ci, di, c2 and d2). Furthermore the fact that well graded concentrates of vitrain and clarain are obtained, is pnt -to account for sending them to purifyers E2 and Es which eliminate sedimental mineral constituents thereof. All the other arrangements of the plant are similar to those of Fig. 1, the same references being used for designating the same members.

The initial coal is linally separated, owing to this treatment, into live products: tailings s, middlings m, a concentrate of fusain f, a concentrate of purified clarain and vitrain vc, purified semi-coke of durain d.

Tailings, middlings and fusain are eliminated with possible use of middlings and fusain for heating the boilers. The concentrate of vitrain and clarain and the semicoke of durain are sent, after proportioning, to coke ovens through the mixer M.

Figs. l and 2 illustrate two forms of the invention applied to two extreme cases. In the former case, the fusain of the long flame coal is pure enough to be entirely used as an impoverishing substance; in the latter case, it is too impure and must be wholly eliminated.

Intermediate solutions with partial elimination of fusain are of course possible. Obviously it is also possible to provide for the demineralization of fusain through elec- `trostatical puriiication or dotation, thus allowing in every case, its use as an impoverishing substance. But as a rule this operation is not advantageous.

The economical advantages of the process according to the invention, are considerable. Said process imparts, to long flame coals, a complete independence as regards coking, since it makes possible -to coke them alone, so that it is no longer necessary to bring, usually from a long distance, costly make-up coals. The only condition required is that the long flame coal should not be an unusual coal containing only too low an amount of softenable vitrain. In such a case, it will of course be necessary to resort to make-up coal, but the amount thereof will always be much less than that required in conventional processes.

Furthermore, the process according to the invention -should make possibie of obtaining in every case a coke having improved qualities as regards cohesion, reactivity and ash, sulphur and phosphorus contents.

What I claim is:

1. The process of manufacturing from badly coking coal containing a high content of volatile matter and carboniferous constituents in the form ofv free particles of' durain, vitrain, clarain, fusain land conglomerates, a good metallurgical coke solely from said constituents comprising the steps of: (a) size-grading said coal to segregate the free particles of the ,durain from the vitrain, clarain, fusain and the conglomerates; (IJ) purifying said segregated durain to substantially eliminate tailings and middlings contained therein; (c) subjecting said purified durain to low temperature distillation to convert it to semi-colte; (d) grinding said semi-coke to a granulometric size of the magnitude of 1 mm.; (e) proportioning and mixing said ground semi-coke with at least said vitrain and clarain constituents; and (f) subjecting the mixture obtained by step (e) to high temperature distillation.

2. The process according to claim 1, comprising the additional intermediate steps of (a-l) disintegrating said conglomerates into -free particles of durain and said other carboniferous constituents; (r1-2) size-grading the disintegrated conglomerates to free the particles of durain from the other carboniferous constituents; (a-3) combining the durain particles obtained by said former and latter size-grading steps before performing steps (c) and (d); and (tz-4) combining at least the clarain and vitrain particles obtained from said former and latter size-grading steps before proportioning and mixing with said ground semi-coke.

3. The process according to claim- 2 which comprises the step of proportioning and mixing said semi-coke with said combined vitrain, clarain and fusain constituents.

4. The process according -to claim 2, comprising the additional intermediate step of purifying said vitrain and clarain to substantialiy eliminate tailings and middlings contained therein.

References Cited in the tile of this patent UNITED STATES PATENTS 1,824,526 Andrews Sept. 22, 1931 1,854,659 Lehmann Apr. 19, 1932 2,085,903' Fitz July 6, 1937 2,091,711 Koppers Aug. 3l, 1937 2,158,816 Curran May 16, 1939 OTHER REFERENCES Davis: Circular 6, 115, April 1929, Fusain, Bureau of Mines, 10 pages.

Claims (1)

1. THE PROCESS OF MANUFACTURING FROM BADLY COKING COAL CONTAINING A HIGH CONTENT OF VOLATILE MATTER AND CARBONIFEROUS CONSTITUENTS IN THE FORM OF FREE PARTICLES OF DURAIN, VITRAIN, CLARAIN FUSAIN AND CONGLOMERATES, A GOOD METALLURGICAL COKE SOLELY FROM SAID CONSTITUENTS COMPRISING THE STEPS OF: (A) SIZE-GRADING SAID COAL TO SEGREGATE THE FREE PARTICLES OF THE DURAIN FROM THE VITRAIN, CLARAIN, FUSAIN AND THE CONGLOMERATES; (B) PURIFYING SAID SEGREGATED DURAIN TO SUBSTANTIALLY ELIMINATE TAILINGS AND MIDDLINGS CONTAINED THEREIN; (C) SUBJECTING SAID PURIFIED DURAIN TO LOW TEMPERATURE DISTILLATION TO CONVERT IT TO SEMI-COKE; (D) GRINDING SAID SEMI-COKE TO A GRANULOMETRIC SIZE OF THE MAGNITUDE OF 1 MM.; (E) PROPORTIONING AND MIXING SAID GROUND SEMI-COKE WITH AT LEAST SAID VITRAIN AND CLARAIN CONSTITUENTS; AND (F) SUBJECTING THE MIXTURE OBTAINED BY STEP (E) TO HIGH TEMPERATURE DISTILLATION.

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