US2189711A - Method for preparing coal - Google Patents

Description

Feb. 6, 1940. J. L. EIGENBROT 2,189,711

METHOD FOR PREPARING COAL Filed April 26, 1938 5 Sheets-Sheet 1 Feb. 6, 1940. EIG'ENBROT 2,189,711

METHOD FOR PREPARING COAL Filed April 26, 1938 3 Sheets-Sheet 2 1940- J. L. EIGENBROT METHOD FOR PREPARING COAL Filed April 26, 1938 3 Sheets-Sheet 3 Patented Feb. 6, 1940 UNITED STATES METHOD FOR. ranmnmc COAL John L. Eigenbrot, Upper Darby, Pa., assignor. to

Westmoreland Coal Company, Philadelphia, Pa., incorporation of Pennsylvania Application April 26, 1938, Serial No. 204,435

4 Claims. (c1. 209-6) This invention relates to a new and useful method for preparing and separating materials such as coal, stone, .ore and the like into two kinds, namely, one that is physically strong and one that is physically weak.

Taking coal as an example, as it exists in its natural bed it is a product of nature and like all products of nature, it is not uniform in composition, structure and strength. If a bed of coal,

10 particularly bituminous coal, be examined from the bottom to the top of the bed, many distinct strata of coal will be found, and these strata will vary in composition, structure and strength. Some strata. will consist of weak friable coal while other strata consist of strong tough coal, and still other strataof part strong coal and part weak coal; also the degree with which adjacent strata adhere to each other will vary greatly. In addition to the coal substance, occurrences of stone,

slate and other impurities are included in the bed of coal.

As the coal is removed from its natural bed and loaded into mine cars it consists of a miscellaneous mixture of all the various kinds of coal of 25. which the bed was composed, including any impurities which lay in the bed. There will be specimens of strong coal, of weak coal and of partly strong and partly weak coal banded together. There will be found a great variation in thesize of the various pieces and somepieces may be so large as to weigh more than 200 lbs. whereas other pieces may be classified as dust. Between these limits, pieces of innumerable intermediate sizes will be found. This mingled mixture of coal, including impurities in the coal as it is loaded into mine cars is termed run-of-mine coal.

While all of the coal as it is brought out of the mine is of the run-of-mine size, not all of 40 the coal shipped to the market is of the run-ofmine size. There is an increasing demand for numerous other sizes, depending upon the manner in which the coal is to be used. For this reason, some of the run-of-mine coal is classifled into various sizes, such as for instance, four by six inches, two by four inches, three-quarters by two incha, and so forth, bypassing the runof-mine coal over a screen or screens provided with sections containing certain size openings.

5 By this means run-of-mine coal can be screened so as to obtain a portion which will not pass through a four-inch opening but all of which will pass through a six-inch opening thus producing a portionhaving a general size of four by six 3 inches. In like manner portions having other sizes are screened out of the run-of-mine coal by using suitably sized openings in the screen.

Due to the constant progress which is being made inthe design and operation of coal consuming equipment and a likewise progress in the I various processes in which coal enters, the combustion or reaction of coal is becoming more and more precise. Not only is the composition of the coal important; its size may be equally important and in some cases may be of even greater im- 10 portance. The rate of combustion or reaction of a piece of coal is proportional to the ratio of its surface to its mass, and the greater thisratio the higher will be the rate of combustion or reaction. The efiect of size upon the ratio of surface! to mass may be illustrated by comparing three pieces of coal with each other, one piece being a cube measuring four inches, another measuring two inches and another measuring one inch. In the case of the four inch cube the ratio of sur- 2 face to mass is 1.5 to 1; while in the case of the two inch cube the ratio is 3 to 1, and in the case of the one inch cube the ratio is 6 to l. Manifestly where the coal varies in size between the limits of four inches and one-inch, uniform combustion 26 or reaction cannot occur, hence in the processes where sized coal is required that coal which will resist the physical stresses imposed upon it during transportation and subsequent handling will be preferred. 80

The processes of makingwater gas and producer gas are examples of cases where screened coal is used to provide a fuel bed of uniform condition that will yield highefficiency and large capacity of the. equipment. Manifestly even though coal 35 be carefully screened so as to keep the component parts of a certain size, between narrow limits at the time it is loaded into railroad cars, if such screened coal is not sufliciently strong to withstand the physical stresses imposed upon it 40 before it is used, it will break and degrade in size thereby impairing its performance and reducing its value. Coal gas retorts can also be cited as cases where uniformity of size is important and where degradation of size due to 45 breakage is equally objectionable.

There are other cases where the size of the coal is unimportant. Such cases for example are coke ovens and steam boilers in which powdered coal is used as fuel. In the case of coke ovens it is the common practice to mix two or more coals in orderto produce coke having specific properties, and in order to blend the coals entering the mixture they are pulverized, hence in this case the size of the coal at the time of shipment 5 from the mines is unimportant, in fact the smaller the size of the coal the less will be the expense of pulverization. Further, there is no objection to weak soft coal, in fact it is preferred to strong tough coal because of the easier tasks of pulverizing it.

From all of the foregoing it is clear that the coal market includes consumers of at least two classes, one in which strong coal of uniform size is required and another in which weak soft coal is required. With this premise in mind, the principal object of the present invention is to provide a novel method of preparing and classifying or separating materials such as coal and the like wherein the coal is deliberately subjected to physical forces to break the weaker coal and to remove from the stronger coal that weaker coal which is handed to it, thus separating the weak coal substantially entirely from the strong coal,

Another object of the invention is to provide a method of the type described wherein the strong coal thus separated from the weak coal may be continually subjected to physical forces to reduce the size thereof to meet market requirements.

Another object of the invention is to provide a method of the type described wherein the strong coal thus separated from the weak coal is subjected to physical forces to round off the sharp edges and corners thereof to meet market requirements.

A further object of the invention is to provide a method of the stated character wherein the separated and reduced weak and strong coal are classified or separated into the various sizes desired to supply the market requirements.

These and other objects of the invention and the features and details of its operation are hereinafter fully set forth and shown in the accompanying drawings, in which:

Figure 1 is a diagrammatic view in perspective of one form of apparatus which may be employed to carryout the present invention.

Figure 2 is an enlarged view in perspective of what may be termed a preparator having certain portions thereof cut away to illustrate various details of its construction, and

Figure 3 is a fragmentary view in perspective of the interior of the preparator shown in Figure 2.

Referring now more particularly to the drawings, reference numeral I designates a declining chute from which run-of-mine coal is discharged into a hopper 2 provided with two outlet chutes 3 and 4 respectively. As shown, the hopper 2 is provided with a plate valve 5 arranged so that run-of-mine coal may be discharged from said hopper through either outlet chute 3 or 4 as may be desired to a chute 6 or onto a scalping screen 1 respectively.

The scalping screen I is provided with a perforated bottom plate or wire mesh material 8 for the purpose of separating and removing the fine coal from the coarse coal. Of course, should it be desired to eliminate this scalping step, the bottom surface of the screen I may be-ccvered with a suitable imperforate plate or sheet (not shown); however, in most instances, the runof-mine coal will be scalped and in order to more clearly describe the present invention, this scalping step or operation should be further described. In this regard, the plate 8 of the scalping screen has perforations therein of, for example, say two inches with the result that as the run-of-mine coal passes therealong from the hopper 2, all the coal of minus two-inch size will pass through said perforations in the plate 5 and be discharged into a chute 9 by means of which this minus twoinch coal is conducted to a screen conveyor described in detail hereinafter. The coal which is plus two inches in size, however, will remain in the scalping screen I and is conveyed by it to a discharge chute ll.

In order to facilitate scalping of the run-ofmine coal and convey the plus two-inch size coal toward the discharge chute Ill, the scalping screen i is preferably of the reciprocating conveyor type suitably suspended upon pivoted arms H and reciprocated by means of an eccentric i2 which is driven by a motor or other suitable source of rotary power II. Upon reaching the chute ill, the coal is conveyed by said chute and discharged into a chute or hopper H which leads into the interior of a preparator, designated generally by the letter P, where said coal of plus two-inch size is treated or prepared and classilied with respect to physical strength and size.

As shown particularly in F.gure 2 of the drawings, the preparator P is mounted for rotation about its longitudinal axis, being driven from a suitable source (not shown) through a gear I5 which meshes with the gear teeth I formed on the circumference of the imperforate wall ll which completely closes the end of the preparator opposite the inlet end thereof. The preparator P is divided into a. suitable number of sections, three being illustrated and designated a, b and 0 respectively, and the walls ll thereof are perforated, for example. by providing say two-inch holes or openings l section a, four-inch openings in section b, and six-inch openings in section c. Through these openings in the walls ll, coal of corresponding sizes will pass from the preparator P into a hopper-chute I! which feeds the assembled coal upon a screen conveyor 2! upon which the minus two-inch scalpings have been fed by means of the chute 9 previously described. This screen 20 is provided with a series of sections d, e, f and 9 having therein one-half, one, two and four inch openings respectively, thus enabling the screen 20 to separate and classify the coal received thereon into sizes of approximately zero by one-half inch, one-half by one inch, one inch by two inches, two inches by four inches and four inches by six inches respectively. These several sizes will each pass through the respective sections of the screen 20 onto conveyors 2|, 22, 23, 24 and 25 which deliver their respective coals to railroad cars, to trucks or to storage bins, or if desired suitable chutes may be substituted for the conveyors 2|, 22, 23, 24 and 25 to deliver the coal by gravity directly into railroad cars or trucks.

Should it be desired to eliminate scalping and preparation of the run-of-mine coal with respect to the strength thereof, that is, to eliminate separation of the strong coal from the weak coal, the plate valve 5 in the hopper 2 is positioned so that the run-of-mine coal will discharge through the chute 3 to a chute 6 by means of which it is fed onto the screen 20 where it will be screened into the sizes previously mentioned with the exception of the four by six-inch sizes which in this case will consist of four-inch lump coal.

The screen 20, a; the case of the screen I, is suspended in the ...ial manner by straps or links 25 from suitable supports, (not shown), and a reciprocating motion is imparted thereto through a connecting rod 21 by means of an eccentric 28 driven by a suitable motor 29.

The foregoing describes the particular course or flow of the coal as contemplated by the present invention, and at this time it is essential that the preparator P. As shown, the preparator P consists essentially of a wall l8 composed of perforated metal plates 30, 3| and 32, suitably fastened to a metal frame 33, the whole of which rotates about its longitudinal axis upon rollers 34 and journal 35. The preparator P is provided with shelves 31 arranged internally and longitudinally thereof to lift the coal during the rotation of said preparator to a point where said coal will fall from said lifting shelves 31 onto the perforated plates 30, 3| and 32, thereby subjecting the'coal to physical forces so as to cause the weak coal to break into smaller sizes and also to break off from the pieces of strong coal to which it may adhere. The lifting shelves 3! are provided with openings 38 therein so that only that which is too large to pass through said openings 38 will be raised and dropped by the shelves 31. The lifting shelves 3'! are detachably mounted within the preparator P to permit the number employed in any instance to be varied and to permit changes in the sizes of the openings 38 depending upon physical nature of the coal and the extent towhich large pieces of strong coal are to be reduced in size. That part of the coal which is not lifted and dropped through the openings 38 in shelves '3! will be subjected to a rolling and tumbling action which will remove or break from the strong coal any weak .coal that may be attached to it, and will further cause the sharp edges and corners of the strong coal to be worn away and rounded. v

In addition to the shelves 31 the preparator P is provided with pusher plates 39 arranged internally thereof at an angle with reference to the axis of said preparator P so that as the latter rotates the coal will be moved from the receiving end of the preparator to the opposite end thereof. The angularity of the pusher plates 39 is adjustable so that the pushing eifect may be increased or decreased depending upon the speed with which it is desired to move-the coal through any one or all of the various sections a, b and c of the preparator. This factor is also controlling as respects the particular number of pushers 39 employed in any one instance or treatment of the coal. A partition 40 is provided between sections b and c of the preparator P and this partition 30 has one or more openings ll therein to permit coal which will not pass through the four-inch holes in section b to enter section 0, closures 42 being provided for said openings II in the partition In so that, in instances where it is desired to prepare the coal so that all of it will pass a four-inch opening of section b, passage of said coal into section c may be prevented. Similarly by providing a similar partition between sections a and b of the preparator and closing the openings therein, all of the coal will be retained in said section a where it will be reduced and prepared until it passes through the two-inch openings of that section. The partition 40 is provided with a concentric or central opening 43 therein to permit a man to pass from section 0 to section b should such an occasion ariseand a manhole having a suitable cover 44 in the closed end wall to permit ready entrance to, and exit from the preparator.

All of the run-of-mine coal may be treated in the preparator P by covering the perforated plate I I of the scalping screen I as previously described, although said scalping screen I is usually utilized for the purpose of relieving the preparator of coal having a'size which is not to be prepared with respect to strength of the coal, and referring to Figures 2 and 3, the plus two-inch coal will be seen in the chute It just as it is about to enter the preparator P which is rotating in the direction of the arrow, arrows being also employed to illustrate the travel of the coal longitudinally through the preparator as effected by the pusher plates 33. Under the influence of the lifting and falling action together with the rolling and tumbling action imparted to the coal; said coal will be prepared or separated into strong coal and weak coal. This involves a reduction in size, and that part of the coal which is reduced to a size not larger than twoinches will pass through the openings inthe walls of section a into the hopper l9 and hence be removed from the zone of action. The coal remaining in the preparator is, however, subjected to continued action, and, under the influence ofthe pusher plates 39 enters section b where all of the coal that is a minus four-inch size will pass through the holes in the walls of said section b to the hopper l9 and hence be removed from the zone of action. That coal which still remains in the preparator will be subjected to continued action and under the influence of the pushers 39 will enter section 0 from which all of the remaining coal that is of a minus six-inch size will pass through the openings in the walls of said section 0 into the hopper l3 and hence out of the zone of action; but that remaining coal which is of a plus six-inch size is retained in section '0 and continuously subjected to the tumbling and reducing action of the preparator until it is reduced to a minus six-inch size so as to pass through the openings in the walls of said section a into the hopper IS.

The continuous action of the preparator P upon the coal will, of course, produce a small amount of coal of flne size irrespective of the section of said preparator in which the action occurs, for example, a piece of coal of such size as permitted it to enter section 0, that is, larger than four inches, may, under the action of the preparator be reduced to say three pieces two of which may pass through a one-inch hole. Such small pieces of .coal would be objectionable if contained in coal of four by six-inch size. To overcome this objection the entire product of the preparator is therefore gathered together upon the screen 20 and classified into various sizes, which need not necessarily be correlated with the size of the holes in the several sections of the preparator, but it is essential that at least two stages be established and correctly phased with respect to each other.

From the foregoing it will be seen that the present invention provides a novel and eifective method or process for preparing and separating coal into strong coal and weak coal, wherein all of the coal received by the preparator is subjected to physical forces which break the weak coal and separate it from the strong coal, which is thereafter reduced to predetermined sizes as may be desired or required, the preparator being provided with means for increasing and decreasing the velocity through which the coal passes through each section of the preparator, as well as means for increasing or decreasing the amount of lifting and falling action and the tumbling and rolling action to which the coal is subjected in any and all of the sections of the preparator P. .The preparator is so constructed that coal entering the same is retained therein and subjected to a preparatory action until the desired end product is obtained, thus avoiding recycling of the coal through the preparator.

. While a particular embodiment of the invention has been illustrated and described herein, it is not intended that said invention shall be precisely limited thereto but that changes and modifications may be incorporated and embodied therein within the scope of the annexed claims.

I claim:

1. The method of preparing coal which co'mprises advancing a mass of coal of assorted sizes progressively through a series of selective separating stages arranged to separate out coal of increasing size progressively through the series, continuously subjecting said coal to physical breaking forces while in the separating stages to reduce the coal into pieces which increase in strength and size as during progress of said coal through said stages, and selectively separating out the reduced coal from the separating stages.

2. The method of preparing coal which comprises-advancing a mass of coal of assorted sizes progressively through a series of selective separating stages arranged to separate out coal of increasing size progressively through the series, continuously subjecting said coal to physical breaking forces while in the separating stages to reduce the coal into pieces which increase in strength and size as during progress of said coal through said stages, selectively separating out the reduced coal from the separating stages, and controlling the speed of progression of said coal through said separating stages to regulate the reduction and separation in each separating stage.

3. The method of preparing coal which comprises advancing a mass of coal of assorted sizes progressively through a series of selective separating stages arranged to separate out coal of increasing size progressively through the series, continuously subjecting said coal to physical breaking forces while in the separating stages to reduce the coal into pieces which increase in strength and size as during progress of said coal through said "stages, selectively separating out the reduced coal from the separating stages, collecting the separated portions of coal without regard to the size and physical strength thereof, and then classifying said coal into groups according to size.

4. The method of preparing coal which comprises advancing a mass of coal of assorted sizes progressively through a series of selective separating stages arranged to separate out coal of increasing size progressively through the series, continuously subjecting said coal to physical breaking forces while in the separating stages to reduce the coal into pieces which increase in strength and size as during progress of said coal through said stages, selectively separating out the reduced coal from the separating stages, controlling the speed of progression of said coal through said separating stage to regulate the reduction and separation in each separating stage, collecting the separated portions of coal without regard to the size and physical strength thereof, and then classifying said coal into groups according to size.

JOHN L. EIGENBROT.

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