US1976292A - Process for separating intermixed divided materials - Google Patents

Description

Oct. 9, 1934. R. PEALE PROCESS FOR SEPARATING INTERMIXED DIVIDED MATERIALS 3 Sheets-Sheet l Original Filed Aug. 31, 1929 R. PEALE 1,976,292 PROCESS FOR SEPARATING INTERMIXED DIVIDBD MATERIALS Oct. 9, 1934.

OrizinalFiled Aug. 31, 1929 3 Sheets-Sheet 2' Oct. 9, 1934 R E L 1,976,292

PROCESS FOR SEPARATING INTERMIXED DIVIDED MATERIALS Origina; Filed Aug." 31, 1929 3 Sheets-Sheet '5 WW &

BY I

. ATTORNEY V Patented st. 9, 1934- PATENT OFFICE PROCESS FOR SEPARA'EING INTERMLIXED DIVIDED lVIATERIALS- Richard Peale, St. Benedict, Pa assignor, by mesne assignments, to Peale-Davis Company, Wilmington, Del., a corporation of Delaware Application August 31,

1929, Serial No. 389,722

Renewed February 16, 1934 13 Claims.

The invention relates to a new and useful process for separating intermixed divided materials, and particularly materials, such as unsized coal, the pieces or particles of which vary relatively -6 greatly in size and vary relatively little in their specific gravities.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by praclO- tice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one form of apparatus for carrying out the invention, and together with the description, serve to explain the principles of the invention.

Of the drawings:

Fig. 1 is a side elevation of a separating table embodying the invention;

Fig. 2 is a top plan of the air pervious deck of the separating table shown in Fig. 1;

Fig.3 is a partly diagrammatic top plan of the separating deck shown in Fig. 2, showing a scheme for the zoning of the air forces;

Fig. 4 is an enlarged detail showing a transverse vertical section of an air-regulating shutter;

Fig. 5 is an enlarged transverse vertical section showing the structure of the reciprocating deck and frame;

Fig. 6 is a fragmentary enlarged detail showing in elevation the structure of the valve for pulsating the air currents;

Fig. '7 is a transverse vertical section on line 7-7 of Fig. 6;

Fig. 8 is an enlarged vertical section on line 88 of Fig. 1, showing a bearing for supporting the shaft of the pulsating valve;

Fig. 9 is a top plan of the sub-deck structure of the separating table, showing the chambers for the sub-areal zoning;

Fig. 10 is a partly diagrammatic top plan of the sub-deck indicating one arrangementof the sub-areal zoning of the air forces; and

Fig. 11 is a fragmentary, enlarged side elevation of a modification of the invention, showing the rear end of a separating table with the controls for the table feed and air supply.

The invention pertains broadly to the separation of intermixed, divided materials, the term taken divided being used to designate broken, fragmentary, granular, pulverulent or other materials comprising separated parts or pieces of difierent kinds of material. The invention in its novel features is more particularly directed, however, to effecting automatic separation, to practically the ultimate degree of possible efficiency of such mixtures of materials wherein the various pieces of the different kinds of materials vary relatively very greatly in size, while varying relatively little in their specific gravities.

With this purpose in view, the invention is further directed to effecting, concurrently with the separating process, an approximate size classification, both of the heavier and the lighter particles, whereby there is attained unusual and practically perfect efficiency in separating suchwidely varying unsized materials. Another ob-- ject of the invention comprises providing a process for controlling and governing the separating forces and conditions to accommodate the separating and sizing action to materials varying relatively greatly in size and frequently in moisture content.

One kind of intermixed divided materials which the invention is especially capacitated to successfully separate, is a mixture of coal, bony and rock, with the other impurities usually present in the coal, as it comes from the mine, that is, run-of-mine coal, except that the large lumps, say from seven inches up are crushed, although this crushing is not necessary even up to pieces ten inches in size. Usually, however, it is simpler to remove a few large chunks of coal and rock than to run them over separating tables. The rock and other impurities are separated from the run-of-mine coal by the present invention entirely automatically, on a single cleaning table, and without previous sizing of the materials, except as to said crushing or removing the very largest lumps, the practically perfect separation being effected down through the finest dust of the intermixed materials.

The conditions of the inventive problem solved by the invention are of the greatest practical difficulty due to the wide range of variations in the sizes of thepieces or particles of the intermixed materials, and concurrently therewiththe rela-- tively small differences in the specific gravities of the materials, and due further, frequently, to a very high percentage of impurities in the finer part of the mixture. Separating work of this kind, with these factors present, requires practically an entirely diiferent process and mechanism or apparatus from the separation of matel of the material may v rated rials which are very finely pulverized and which vary very widely in their specific gravities on the one hand, or which, on the other hand, are very carefully and extensively sized prior to the separating process. This is especially true in the separation of coal, particularly bituminous coal, different lots or runs of which may vary greatly in their characteristics, especially as to the ratio of coarse particles to fines, the amount of impurities in the fines or in the larger sizes, the friability of the particles, and in the frictional qualities of the coal and impurities; and also in moisture content.

The terms lighter and heavier as used hereinafter will be understood as applying to the specific gravities of the various intermixed, divided materials and not to the difference in mass of particular pieces of various sizes.

According to previous commercial practice in separating or cleaning intermixed materials varying relatively greatly in sizes of the pieces or the particles, while varying very little in the specific gravities of the materials, and especially in the cleaning of coal, it has been necessary to very closely size the coal by preliminary screening before attempting the automatic separation of the intermixed coal, bony, rock and-other impurities. This previous commercial practice has necessitated the employment of a large number of screening or sizing devices, and likewise a corresponding number of small tables for separately cleaning the thus sized or classified coal, one table being necessary for each of the sized classifications of the coal created by the screening devices. It has been quite usual to employ six or eight screens and the same number of small cleaning tables to clean run-ofmine coal, of sizes, say-from three inches down, while eflicient cleaning of the larger sizes has been impossible of accomplishment by such tables.

One of the important and broad objects of the invention is to provide a control and regulation of the concurrent sizing action, whereby the effects of this action may be utilized in further ing and perfecting the removal of impurities from the coal or other material to be cleaned or separated. With this object in view, the invention provides a flexible method and means for controlling and changing the size classification of the particles of the material at different stages of the separating operation, in order to accommodate the process to the separation of materials having widely different characteristics.

By virtue of the invention, the position or 10- cation of the different sized particles in the bed of materials being treated can be governed and flexibly manipulated so that a material present-' ing practically any set of characteristics can be treated with the utmost efficiency.

More specifically, the invention provides a process whereby the different size ranges of particles can be transposed and positioned in the bed practically at the will of the operator. The fines and the coarse particles can be made to arrange them- J selves at the most desirable locations of the bed during a given stage of the separating operation and, if desired, to reverse their respective locations during later stages of the operation, so that the separation of the different size ranges be accomplished with the greatest facility.

The invention is particularly directed to providing a separating process wherein the refuse fines may be very easily and efficiently sepafrom the mass of intermixed materialsj without requiring any separate or special treatment or mechanism. In separating tables used at present, the most serious difiiculty encountered is that of removing the very fine refuse particles which tend to cling to and remain intermixed with the otherwise clean coal or lighter material. This difiiculty is especially prevalent among the relatively soft bituminous coals, which are very friable and frequently contain soft dirty streaks. The ratio of refuse to coal in the different size ranges of unsized coal varies greatly in different coals. In some coals the greater percentage of slate, sulphur and other impurities will be found in the larger sizes, and this type of coal can be very efficiently cleaned on separating tables by already known processes. However, the refuse or impurities in many coals is found in large proportion among the smaller sized ranges of the particles, some coals containing as much as 35 or 40 per cent of the total refuse in the finest sizes.

In handling the latter type of unsized coal by known separating processes, it is extremely difficult to remove the fine refuse particles by' the same treatment as that applied to the ordinary and larger sized particles without causing a remixing of the fines with the cleaned and partially cleaned coal. To avoid this difficulty it has heretofore been necessary to provide special devices and additional mechanisms for separately or specially treating and retreating the fines so as to reduce the impurities in the coal to near the theoretically possible minimum as shown by the washability curves.

In common with other and earlier separating processes, such as that disclosed in my copending application Ser. No. 387,397, filed August 21, 1929, in the present preferred embodiment and practice of the invention, a relatively deep bed of the intermixed materials is maintained in substantially continuous progression along a transversely inclined air-pervious table which is reciprocated, preferably in the direction of its length. Lifting and loosening air currents are blown upwardly through the bed to loosen the particles apart and to stratifythem, by permitting the impurities to gradually settle to the table surface, while the coal is maintained as a substantially fiotant and superposed stratum. The settled heavy impurities are impelled to the upper side edge of the bed and from along direct and non-cumulative paths, substantially immediately upon their settling, by a series of transversely disposed separating partitions, while the fiotant coal progresses freely forwardly along the table to discharge at the front end thereof.

The lifting air force to which the bed is subjected, especially in the rear portion thereof, is sufficiently strong to effect a substantially vertical size and specific gravity classification of the particles, so that the finest particles of coal are blown to and supported at the top of the bed, and onlythe largest and heaviest lumps of rock are allowed to settle to the table surface, while the superposed and intermediate particles of coal and rock arrange themselves in the rising air current substantially according to size and specific gravity.

The separating partitions direct the large lumps of settled rock to discharge at outlets near the rear end of the bed. The separating partitions also co-operate to efiect a transverse size classification of the other particles in the bed, by

to discharge there-.

retarding and deflecting the partially submerged 159 difficulty of handling large coal particles, so that the largest coal gradually arranges itself adjacent the upper and outer side edge of the table, while the freely floating fines fiow over the separating partitions and gather along the inner and lower side edge of the table. By virtue of this action the stratum of coal becomes transversely classified according to size across the forwardly-moving bed. The finer particles of refuse are also influenced by the transverse sizing operation, so that a considerable portion of the fine refuse will be eventually found with the fine coal along the inner and lower side of the table.

The hereinbefore-describedoperation sufiices very well to accomplish the separation of the larger particles of refuse, particularly in the rear portion of the bed, but the continued progress of the bed along the table with the concurrent carrying out of the above-described transverse sizing operation, engenders difficulties, particularly with certain types of coals. As the operation progresses, the large coal lumps crowd up against the upper and outer side wall of the table and interfere with the discharge of the settled refuse. Furthermore, particularly withcoals in which the refuse is largely composed of small particles, the accumulation of the fine refuse with the fine coal along the inner and lower side of the bed produces a most difficult separating problem. The 30 fine particles must not only be settled out by gravital Stratification from the fine coal, to which they tend to cling and remain intermixed, but the fine settled refuse must then be progressed clear across the table by the separating parti- -tions to discharge with the other refuse at the upper and outer side edge of the table. This long path of travel for the fines is disadvantageous because it is especially difficult to move fine particles along a frictional surface, to which they tend to cling and settle.

Furthermore, during the progress of the fine refuse across the table, much of this fine material is blown up into and remixes with the superposed and clean coal.

By virtue of the invention, the above-described the fines is entirely obviated, while all the advantages of the formerly used and herein-before-described process of separating the materials are preserved. I have discovered that the separating conditions and forces to which the bed of materials is subjected can be so varied and controlled as to effect a practically complete reversal of the size arrangement of the particles in the bed. Furthermore, by properly regulating and varying the separating forces, the size arrangement of the particles at any given location in the bed of materials, or at any given stage in the separating process, may be determined and changed substantially as desired in order to allocate a given size range of the particles at that location in the bed which is most desirable for efiicient cleaning or separation.

For example, and according to the present preferred practice, at any desired stage in the separating process the fine material, which has started to gather along the lower and inner side of the bed,.can be made to reverse its transverse movement and to gather along the upper and outer side edge of the table and adjacent the dis charge devices for the settled refuse. Simultaneously the large coal particles are mutually transposed with respect to the fines and move across the bed to arrange themselves along the inner and lower side of the bed. The same movements take place to lesser degrees with the intermediate sized particles', so that ultimately the transverse size arrangement of the bed is completely reversed.

The described reversal of the sizes of the particles in the bed automatically transposes the fines to the upper and outer side of the table adjacent the refuse discharge devices, and thus greatly facilitates the settling out and discharge of the fine refuse. The problem of moving the settled fine refuse clear across the table is com pletely and automatically obviated. Furthermore, the large coal lurnps are moved away from the refuse discharge points and no longer clutter up the discharge openings.

The reversal of the size classification and the mutual transposition of the different size ranges of the particles is accomplished substantially as follows:

After the initially-settled (and chiefly the largest) impurities have been removed from the bed of coal by the separating partitions in the rear portion of the bed; and after the superposed coal and residuary refuse particles have taken up a transversely classified arrangement, with the large particles working toward the upper and outer side edge. of the bed, and with the fines gathering near the lower and inner. side of the bed; the forwardly-progressing bed moves on to a forward area of the table and is there subjected to a lifting air pressure of radically reduced strength.

The lifting power of the air in said forward area is no longer sufficient to maintain the particles in the vertically sized relation effected by a strong lifting current. vAs a result, the fine particles are no longer floated at the top of the bed and begin to sink below the upper edges of the separating partitions. The fine particles also filter down between the larger lumps and eventually build up beneath the latter. Accordingly, the larger lumps tend to work nearer the upper strata of the bed and to climb and roll over the tops of the separating partitions. As these movements continue, the separating partitions gradually direct the settling fines toward the upper and outer edge of the bed, while the large lumps struggle over the separating partitions and roll and work toward the lower and inner side edge of the bed. Eventually there is effected a mutual interchange of the diiferent size ranges on the table, so that the fines are adjacent the upper and the coarse particles adjacent the lower edges respectively.

In other words, by abruptly reducing the lifting strength of the air current the condition of the particles in the bed is changed from that wherein the fines are fiotant and the coarser particles are stratified below according to size and specific gravity, to a condition approaching the vertical sizing which exists when no lifting air pressure is used. It is well known that when particles of different sizes are shaken or vibrated to. gether under the settling influence of gravity alone. the particles will assume a vertically sized relation wherein the fines filter through the coarser particles and form at the bottom, while the coarse particles arrange themselves upwardly inorder of increasing size. In the present process, the particles in the rear portion of the bed undergo an air pressure sufficiently strong to maintain the particles in that vertically sized re lation wherein the finest and lightest particles are maintained fiotant while the coarser particles sink nearer to the table surface, and as already described, the separating partitions operate to transversely size the bed by retarding the larger and more submerged particles while the fines float freely above them, But under the very mild action of the reduced air force, the fines can no longer float above the separating partitions, and thus tend to settle, while the coarse particles, which are more strongly impelled by the reciprocating impulses, work upwardly and over the separating partitions and toward the lower edge of the table. Hence, by approaching a condition approxir-iating a reversal of the vertical size stratification effected by a strong rising air current, a complete reversal in the transverse classification of the bed is gradually accomplished.

It will be clear, however, that on the forward areas of the bed there is still maintained an air pressure sufficient to cushion the movement of the particles over the bed and to permit stratification of the particles according to specific gravity, so that the heavier particles in the forward part of the bed are still able to settle as an inferior stratum beneath the relatively flotant coal. In other Words, a reduction of air pressure in the forward portion of the bed is not sufficient to destroy or prevent a gravity Stratification of the particles, and therefore eflicient separation of the remaining impurities in the bed is accomplished.

Another and important aspect of the invention relates to the process for accommodating the action of the table to comparatively sudden changes in the quality or characteristics of the material fed thereto such as frequent variations in the moisture content of the coal, or variations in the proportion of fines in the mass. The run of coal from some mines will vary greatly in moisture content almost momentarily. Furthermore, the percentage of fines from the same mine may vary rather frequently. For example, in the mornings the coal usually contains a relatively large quantity of slack or fines from the cuttings of the night before, while coal later shot down may run in larger sizes.

Coal which contains a relatively great quantity of moisture requires a much greater air force to effect a like loosening and stratification on the same quantity of drier coal. When the coal is high in moisture, and especially when there is a high percentage of fines, the bed will compact and slide along the table as a cohesive mass without properly stratifying, unless a relatively very great air force is passed through the bed, especially at the rear end of the table. In fact, if the moisture content becomes excessive, the coal will refuse to move at all, but will pile up at the feed hopper in a heap several feet deep.

It is not always possible to maintain the desired stratification of the bed by variations in the air forces alone, especially where the feed runs fairly high in moisture, with rapid changes in moisture content. When the coal is very wet and fine, even the maximum blast from the fan may be insufficient to properly stratify the bed, especially when it is desired to subject the forward portion of the bed to a relatively weak airforce, for the purposes hereinbefore described. I have discovered that the effect of relatively great variations in the air force may be achieved by varying the, depth of the bed of materials on the table in conjunction with the control of the air supply, the variations in the depth of the bed being accomplished by controlling the feed of the materials to the table in coordination with the flexible variations in the general air supply hereinafter described in detail. In this way much greater effective variations in air power are realized, while the control of the separating forces is rendered much more flexible and exact.

It will be understood that the foregoing general description, and the following detailed description as well, are explanatory and exemplary of the invention but are not restrictive thereof. It will also be understood that the theory of operation as outlined represents my present best understanding thereof, but should not be construed as restrictive of the actual manner of operation, which is in practice to secure the results stated; nor should the invention be limited thereby.

Referring now in detail to the apparatus for carrying out the invention illustrated by way of example in the accompanying drawings, an air- DBI'ifiOllS table or deck 1 is provided, which is rendered air-pervious in any suitable way, and may consist of perforated metal sheets, the relative areas of the perforations and the solid portions determining the degree of air-perviosity, and variations made in these relative areas affording means for zoning or varying the degree of air-perviosity in different parts of the table. The table is preferably of rectangular form and relatively long and narrow, except that the spillage edge for the coal at the front of the table is transversely or obliquely disposed, at a relatively long angle with respect to the body of the table. Retaining Walls for holding the bed of materials upon the table are provided, comprising a transverse bed-retaining wall 2 at the rear end of the table and bed-retaining walls 3 and 4 extending along either side thereof. A mechanically driven and regulable feeding hopper 5 may be provided for feeding the intermixed materials to the rear end of the table.

The table is mounted for longitudinal reciprocation, through a relatively short path, over a stationary air chamber from which are supplied the air currents which through the bed. As embodied, the walls 2, 3 and 4 extend downwardly below the table surface and are attached on their outer sides tov a supporting frame 10, which preferably consists of angle beams fastened together at the corners of the table structure. The air-pervious deck 1 is supported by means of an inner box-like frame 11 fixed on the inner sides of the retaining walls 2, 3 and 4. A series of longitudinally extending supporting beams 12 divide the frame 11 longitudinally and serve to support the intermediate portions of the deck. The deck is also supported by a series of cross-beams 13, extending transversely of the beams 11 and serving to divide the space beneath the deck into a plurality of relatively small, mutually isolated chambers 70. The beams 11 and 12 rest upon a sub-deck or partition 14, which is fixed to the bottom edges of the mner frame 11. The sub-deck 14 is apertured with a plurality of spaced-apart perforations 15, and this sub-deck, together with the chambers formed by the beams 11 and 12, comprises a part of the air current control system which will be later described.

The means for reciprocably mounting the table upon the stationary air chamber, as embodied, comprises a plurality of supporting arms or links 16, arranged at intervals along either side of the supporting frame 10 of the reciprocable table, these arms 16 being pivotally connected to the frame 10 at their upper ends, and at their lower ends are pivotally mounted in the longitudinally-disposed side members 17 of the top frame of the air chamber proper. The air cham ber 20 is non-reciprocable, but may be longitudiare forced upwardly 1 IIC ' rear. end 47 of the stationary air chamber.

nally variably inclinable together with the table itself, as will be later described. The pivotallyconnected supporting arms 16 are upwardly and backwardly inclined, whereby the short reciprocating movement of the table is relatively slow upwardly and forwardly and relatively quick backwardly and downwardly.

' The means for effecting a reciprocatory movement of the table may be of any known or suitable form. As embodied, a connecting rod or pitman 23 is connected to the rear end of the table frame 10. This rod may be driven by any suitable reciprocating mechanism, such as an eccentric on the drive shaft 24. The shaft 2% may be connected to any suitable driving means, as by the belt 25 running on drive pulley 26. The table drive may embody a regenerative feature, such as the springs 27, which are slidable on rods 28 attached to the forward end of the table. The rods are adapted to reciprocate through apertures in the stationary member 29, upstanding from the forward end of te frame 1'? of the air chamber, and have nuts screwthreaded on their forward ends for compressing the springs against the member 29. This mechanism serves to pull the table forwardly and upwardly, at the end of the rearward and downward strokes eifected by the reciprocating drive. The springs 27 also serve as buffers to take up the shock of the table movement.

The reciprocable table, and the non-reciprocable air chamber are longitudinally tiltable to Vary the longitudinal inclination of the table. As embodied, the rear end of the upper framework 17 of the air chamber is pivotally mounted at 35 on the fixed support 36, while the intermediate and forward portions of the frame are pivotally supported on downwardly extending screw rods 37, which are in turn pivotally mounted on fixed supporting pillars 38. Nuts 39 are screw-threaded on rods 3'7 and bear against the upper side of the pillars 38. By turning these nutsat the various points along both sides of the structure, the longitudinal inclinations of the table maybe varied as desired. Suitable mechanism (not shown) may be provided for varying the transverse inclination of the table, which normally is higher on the outer side 3 adjacent the refuse discharge devices (Fig. 5). The devices for varying the transverse inclination of the table may be of any known or suitable form, as for instance the mechanism shown in the copending application of Richard Peale and Kenneth Davis, Ser. No. 283,690, filed June 7, 1928.

The embodied means for providing the lifting air currents and for forcing them through the bed of materials comprises a stationary air chamber 20, which is suspended from a frame of I beams 17. The stationary air chamber and the reciprocable table are connected together by a flexible air-impervious member such as a canvas juncture 40.

The air currents may be supplied by any suit able means, such as a rotary fan l5 which sup plies the air current through a duct 46 into the The duct 46 and the air chamber may be connected by flexible air-tight means 48, to pen. it of the angular movement of the air chamber in regulating the inclinations of the table as already described. Means for primarily regulating the gen-- eral supply of air to the table may be utilized in carrying out the invention and, as embodied,

comprise shrouds or veils 5O slidably mounted on tracks 51 at the fan inlet, and variably position able to regulate the amount of air supplied to the fan and thence to the air chamber 20. Another form of means for varying the entire air supply to the table, and which may be used either together with the fan veils or as a separate and alternative means, comprises an air-regulating valve or shutter device 52, preferably mounted in the air duct i6 adjacent the flexible connection L8. The valve member 52 preferably comprises a plurality of small, pivotally-mounted shutters 53, similar to the ordinary window shutters, positioned in superposed relation across the duct 46, so that the air blast passing through the duct can be minutely controlled in amount. The individual shutters 53 are preferably mounted for simultaneous opening and closing movement and operable from the outside of the duct 45. Although other forms of air valves may be used for this purpose, the type shown is preferred because the individual spaced-apart shutters interfere as little as possible with the straight forward passage of the air current, and introduce practically no eddy currents or cross blasts.

A third optional form of means for controlling the general air supply comprises a multipleshutter valve mechanism 55, which is positioned in the air chamber 20 intermediate the ends of the air-pervious deck 1. The structure and operation of the valve 55 may be substantially identical with that of the valve 52 already described. The position of the valve 55 is variable longitudinally of the air chamber, according to its use, which will be hereinafter described.

In the present pref-erred arrangement of separating partitions upon the surface of the airpervious deck, all of the separating partitions are inclined forwardly and outwardly, that is, toward the longer or outer and upper side of the table shown in Fig. terminating. at or near the bed-retaining wall 3. These separating partitions are parallel to each other and preferably extend at an angle to the oblique or diagonal front coal spillage edge 61 of the table, so as to direct the settled heavier material away therefrom. As described in my earlier copending applications, the diagonal form of coal discharge edge provides a progressive discharge for the transversely sized coal stream. The separating partitions 65 may decrease in height forwardly of the table (Fig. 1) and may also decrease in height toward the inner side.

The discharge boxes 65 for the rock and other impurities may be of any known or suitable form such as is shown in copending application Ser. No. 283,600 above-referred to, and they are here shown more or less conventionally. These boxes will be located at. proper points along the table, will be connected through variable-sized openings '70 in the bed-retaining walls 3, and have the operations and functions described in said application. Likewise as shown in said application, a header 65 is provided above and alongside the deck, bein supplied with air by opening 67 in the side wall of the air chamber, having individual flexible air connections 68 with the various refuse discharge boxes 55 and being provided with air current regulating devices 69.

Referring now to the means for effecting the hereinb-efore-described control and allocation of the size classification of the particles in the bed, the relative lifting strengths or intensities of the rising air forces in different areas of the bed play a very important part in these functions. Generally speaking, the rear portion of the bed, up to the first or second refuse discharge boxes 65 (numbered from the rear or left-hand end of Fig. 2) is subjected to a relatively strong lifting air force to effect the primary vertical sizing and stratification of the particles by floating the fines and permitting the largest particles of heavy refuse to settle. The large settled refuse is substantially immediately discharged transversely from the bed through the rearmost discharge boxes 65 by the deflecting and impelling action of the separating partitions. Concurrently with the settling and discharge of the relatively large particles of refuse in the rear portion of the bed, as hereinbefore described, a size classification of the superposed coal and smaller refuse particles takes place transversely of the bed, the larger particles moving toward the upper and outer side 3 of the table and the fines floating forwardly and down- Wardly toward the lower side 4.

The area of the bed in which the above-described primary separating and sizing operation takes place may extend forwardly of the bed as far as desired, and will vary considerably with the relative proportion of large refuse particles in the type of coal being treated.

For many coals and particularly those in which there is a relatively large proportion of the refuse in the smaller sizes, the area of the relatively strong air current will occupy that trapezoidal the remaining impurities. I discharges as a purified and transversely sized area in the rear of the bed indicated as zone a (Fig. 3), the front or forward edge of which extends substantially parallel to the separating partitions 60 and up to the front end of the second refuse box 65. It will be understood, however, that so far as the broad features of the invention are concerned, the relative areas of the different air pressure zones are not limited to any particular location on the table.

In bringing about the reversal of the transverse size classification of the particles, the bed progresses generally forwardly onto a zone I) of preferably rather abruptly reduced lifting force. The lifting force of the air current in zone I) is insufficient to maintain the primary vertical size stratification and, as hereinbefore-described, the fine particles immediately begin to settle behind the separating partitions and move toward the upper and outer edges of the table while the large particles work over the separating partitions and to- 50 ward the lower side edge 4 so that gradually a reversal of the transverse sizing takes place. The lifting force of the air in zone I) is still sufficient, however, to effect a gravity Stratification of the particles, so that the rock and other impurities ll settle lowermost and are directed outwardly and upwardly along the table and discharge through the more forward refuse boxes 65. As the bed progresses still farther along the table, undergoing a gradual elimination of the impurities and an increasing perfection of the reversed transverse sizing operation, zones and d, of respectively lower graduated lifting force are provided toward the forward end of the table for handling Ultimately the coal stream over the spillage edge 61, the particles being arranged in order of decreasing size outwardly toward the forward tip of the table.

The zoning of the air currents so far described is usually effected by variations in the perviosity of the perforated metal sheets making up the deck surface 1. As practiced at present for many coals the relative proportions of air-perviosity in n the zones a, b, c and d are respectively 3 :1 and 0.625, although it will be understood that the invention is by no means limited to these figures.

In perfecting the reversal of the transverse sizing, it has been found that the largest particles, which gather along the lower and inner side 4 of the deck, should preferably be subjected to a still further decrease in air-lifting force to promote their reversed transverse classification. Means are provided for accomplishing the desired decrease of air pressure along the lower and inner side of the table, and as embodied,

comprise the sub-areal air control chambers 70.

The mutually isolated chambers '70 provide means for independently controlling the air supply to the table throughout relatively small independent areas of the bed, by virtue of the removable stoppers '71 for varying the admission of air from the main air chamber 20 through the perforated sub-deck 14. The sub-areal chambers '70 are utilized to form a relatively narrow sub-zone s (Fig. of reduced air-pressure extending along the lower side of the table, for flexibly and more perfectly controlling the movements of the largest coal particles as described. To facilitate the reduction of the air pressure in sub-zone s, and to render the flexibility and nicety of air regulation even more minute, the apertures a in the lower and inner side of the sub-deck 14 may be of smaller diameter and more closely spaced than those in the other parts of the sub-deck (Figs. 5 and 9).

The regulation of the air-lifting forces in the different parts of the bed, and particularly the provision of the relatively abrupt decrease in air force between the zones at and b may be facilitated and rendered more effective by other forms of air-regulating means capacitated to cooperate with the deck zoning mechanism already described. With certain types of coals, it will be found most effective to control the general supply of air to the entire air chamber, so that the lifting force of the air currents, particularly in the low pressure zones b, c and (1, will be very much lower than that formerly used in separat ing tables such, for instance, as that shown and described in my earlier copending application Ser. No. 387,397, filed August 21, 1929.

The embodied means for effecting the desired general reduction and control of the air supply, preferably comprises the veils 50, mounted at the air supply inlet for the fan 45. By raising or lowering these veils as required, the total supply of air to the chamber 20 can be closely regulated, and thus the air pressure in the zone b made sufiiciently low to bring about the hereinbeforedescribed reversal of the size classification. Another method of accomplishing the same function is to provide the fan drive with change speed mechanism, and changing the speed of the fan as required. This method has the added advantage of saving power when a low air force is desired.

Another mechanism for effecting substantially the same result comprises the multiple shutter valve 52, positioned in the air duct 46. By simultaneously actuating the individual shutters 53, the total air supply to the chamber 20 may be accurately controlled, independently of or in conjunction with the fan control.

The means for regulating the general air supply to the table so far described, i. e. the regulation of the supply to the fan, the control of the fan speed, and the multiple shutter 52 located in the air duct 46 all contemplate that the difference in air-perviosity between the rear zone a and the forward zone I) will be sufiiciently abrupt to cause the desired reversal of size classification, and at the same time give a sufiiciently strong air force in the rear zone (1. Under some operating conditions, and with certain types of coals, it may be found that the desired abruptness of pressure change and sufficiency of air forces cannot be obtained by the zonings of the air-pervious deck alone. To meet these contingencies, optionally usable means may be provided for further varying and controlling the air pressures between the rear and forward portions of the bed, and, generally speaking, between the strong rear zone a and the low pressure forward zone I).

As embodied, the multiple shutter valve 55, located substantially medianly between the zones at and b, and preferably about the rear end of the second refuse box 65, may be optionally employed to cut down the air supply to the forward portion of the table and to correspondingly augment the air pressure in the rear portion of the table. It will be understood that the longitudinal position of the valve is not fixed, but may be varied as desired by sliding it along the air chamber on suitable trackways. By virtue of the air valve 55, the relative change of pressure between the rear and forward portions of the table may be made very abrupt or pronounced and may be flexibly regulated as desired. It will be understood that the air valve 55 may be employed independently of or in conjunction with the hereinbefor-e-described means for regulating the general supply of air to the table. With some types of coal, the rear portion of the bed will be best treated by receiving the full blast of air from the fan, the abrupt reduction in the general. supply of air to the forward portion of the table being accomplished solely by the shutter 55, cooperating with the zoning of the deck perviosity. Under other conditions, the shutter 55 may be used in conjunction with the hereinbefore-described fan supply control and/or the shutter 52, so as to further influence the reduction of pressure in the forward portion of the chamber 20.

Still another means for controlling the air currents in the different parts of the bed and also generally throughout the table, comprises means for creating pulsations in the air currents. As embodied, the rotatable shutter '75, which is variably positionable longitudinally of the air chamber 20, serves to create pulsations in the air current supplied to the bed, and when located longitudinally medianly of the table, causes the air pressure in the rear portion of the air chamber to vary between maximum and intermediate pressure limits, while the air currents in the forward portion of the bed beyond the rotatable shutter vary between the intermediate and minimum pressure limits. The rotatable shutter '75 for creating pulsations in the air currents is optionally employed with any or all of the hereinbefore-described means for controlling the air currents. Of and by itself the rotatable shutter V5 serves to create a substantial pressure differential between the rear and forward portions of the bed and thereby cooperates in bringing about the desired reversal of the transverse size classification of the particles.

The present preferred location for the rotatable shutter is substantially one-third of the distance between the described location of the air shutter 55, and the point 76 where the table begins to narrow forwardly because of the diagonal discharge edge 61. However, means are provided for variably positioning the shutter shaft, comprising spaced apart hub bearings 80 in either side wall of the air chamber 20. The embodied means for rotatably driving the shutter 75 comprises a sprocket wheel '77 keyed to the shaft 81 and driven by a chain 78 from the main table drive shaft 24. As shown in Figs. 6 and 7 the shutter '75 may comprise a pair of blades or wings 79 variably positionable radially for changing the diameter of the shutter to accommodate it for different positions in the air chamber and to vary its pulsating effect.

Referring now to those features of the invention relating to the control and variation of the depth of the bed of materials in conjunction with the regulation of the air supply to accommodate the table to differences in the moisture content and other variations in the coal, for the best operation of the process, it has been found desirable for the table operator to continuously watch the bed of materials on the table and to instantly vary both he feed and the air supply as required. By carefully watching the depth of the bed of materials, especially near the rear portion of the table, the operator can quickly detect compaction of the bed due to an increase of moisture or the like and change the air power and/or the feed to meet the changed conditions.

In cases where the changes in moisture in the coal are very frequent-and relatively large, it is desirable for the operator to be able to immediately and simultaneously make the necessary variations in feed and air control. In the embodied form of the invention, means are provided whereby the operator may watch the condition of the bed and simultaneously control the feed to the table coordinately with any or all of the main air-supply controls hereinbefore described.

As embodied, (Fig. ll) the feed hopper is provided with variable-speed drive for the feed comprising a rotatable hopper valve mounted on a rotatable shaft 84: near the mouth of the hopper. The shaftB-l is driven from a pulley 85 which is connected by belt 86 to the drive pulley 87 or" a Reeves variable speed transmission 88, or other known or suitable variable speed mechanism. The driven pulley 89 of the speed transmission may be connected by a belt 90 to any suitable power mechanism.

A platform 91 may be provided adjacent the rear refuse box 65 whereby the table operator may watch the condition and depth of the bed and the quality of the material coming through the refuse opening. Means are provided whereby the operator may regulate the feed of the ma terial while stationed at the platform 91. As embodied, the shaft 92 for controlling the speed variations of the feed is operatively connected by bevel gears 92 to a downwardly-inclined shaft, the upper end of which is rotatively mounted in a bracket fixed to the casing 88 and the lower end of which is rotatively supported in a bracket 94 fixed to the rear of the platform 91. A control handle 95 is fixed to the lower end of shaft 93.

Distant-control devices for the air-supply controls are also provided at the operators platform, whereby the supply can be changed simultaneously with the feed and without requiring the operator to leave his station. As embodied, the veils 50 on the fan 45 are suspended from over:

head pulleys by ropes or cables 97, the cables being attached to the lower end of a control lever 98 pivctally mounted at 99 on the platform 91. A pawl on the lever cooperates with notches in the quadrant 100 to hold the lever at the desired setting. The veils 50 may be appropriately weighted lit so that they tend to slide to their lowermost position on the guides 51. a

. The multiple-shutter valve 52 may also be provided with a similar distant control. Asem-, bodied, the control lever 105 is mounted on the platform 91 and is connected by a pivotally attached rod 106 to one arm of a bell crank 16? pivotally mounted in the side wall of the air duct 6. The other arm of the bell crank has a pinand-slot connection with a vertically movable rod 108, which serves as an actuator for the individual shutters 52 to which it is pivotally connected by separate levers 110. A tension spring 109 is also connected to the arm of the bell crank to normally urge the valves 52 to openposition. If necessary or desirable a similar control mechanism may be provided for operating the medianly positioned valve 55.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles or" the invention and without sacrificing its chief advantages.

What I claim is:-

1. In a process for separating intermixed, divided materials varying relatively greatly in size, the steps of moving a bed of the materials over a support and concurrently classifying the particles in the upper strata thereof according to size while subjecting said bed to a buoyant fluid medium of regulated force, and subsequently mutually transposing the particles of the classified bed to substantially reverse the original size arrangement of said particles by varying the force of said medium.

2. In a process for separating intermixed, divided materials varying relatively greatly in size,

' the steps of moving a bed of the materials over a; support and concurrently classifying the particles in the upper strata thereof according to size while subjecting said bed to a buoyant fluid medium of regulated force, transverselyof the directionof the beds movement, and subsequently mutually transposing the particles of the classified bed to substantially reverse the original transverse size arrangement of said particles by varying the force of said medium.

3. In a process for separatitng intermixed divided materials the particles of which vary relatively greatly in size, the steps of moving a bed of the materials over a vibrating support, effecting a size classification of the particles in the upper strata transversely of the beds movement by forces including rising air currents, friction and inertia, and subsequently radically changing the force of the air currents to effect a reversel of the size classification.

4. In a process for separatitng intermixed divided materials the particles of which vary relatively greatly in size, the steps of moving a bed of the materials over a vibrating support, effecting a size classification of the particles in the upper strata transversely of the beds movement by forces including rising air currents, friction and inertia, and subsequently radically reducing the force of the air currents to efiect a reversal of the size classification.

-5. In a process for separating intermixed divided materials varying relatively greatly in size, the steps of progressing a bed of the materials along an air-pervious support while vibrating the support and passing through the bed lifting air currents of a strength sufiicient to vertically grade the particles of the bed according to size and specific gravity, whereby the lightest and finest particles are floated on the top of the bed and the heavier and coarser particles arrange themselves in lower strata, moving the particles of the bed with respect to each other to effect a substantially horizontal size classification thereof, thereafter subjecting the bed to air currents of greatly reduced lifting force, and substantially reversing the horizontal classification of the particles.

6. In a process for separating intermixed divided materials varying relatively greatly in size, the steps of moving a bed of the materials over a support and effecting a gradual specific gravity stratification thereof, including subjecting substantially all parts of the bed to a buoyant fluid medium, concurrently moving the larger particles toward one side of the bed and the fine particles toward the other side to effect a size classification of the particles transversely of the general direction of movement of the bed, and thereafter mutually transposing the particles by moving the larger and finer particles to the respectively opposite sides of the bed through regulation of said buoyant medium.

7. The process of separating intermixed divided materials varying relatively greatly in size and relatively little in their specific gravities, which comprises acting on substantially all parts of a substantially deep bed of the materials with lifting air currents and mechanical vibration while progressing the bed generally forwardly along a support, classifying the particles according to size transversely of the general direction of the beds progression whereby the finest particles arrange themselves at one side of the bed and the coarsest particles at the other side, and thereafter substantially reversing the transverse size classification of the particles in the bed.

8. In a process for separating intermixed divided materials varying relatively greatly in size, the steps of moving a bed of materials over a support, and-effecting a gradual specific gravity strat-- ification thereof including subjecting the bed to a buoyant fluid medium, classifying the particles of material according to size across the bed by arranging the fines at one side of the bed, and the coarse particles at the other, subsequently substantially reversing the size arrangement of the bed by mutually transposing the fines and coarse particles, and selectively controlling the time and place of said reversal for materials having different characteristics by regulating said buoyant medium along the bed.

9. In a process for separating intermixed divided materials composed of particles having a substantial variance in size, the steps of moving a bed of the materials over a support and-over a rising current of air, retarding and transversely moving the larger particles to gradually efiect a transverse classification of the particles according to size, and thereafter reversing the size classification of the bed by retarding and transversely moving the finer particles while freeing the larger particles for forward movement and while maintaining said rising air current.

10. A process for concurrently sizing and separating intermixed divided materials the particles of which have a substantial variance in size which comprises progressing a bed of the materials generally forwardly along a transversely inclined, air-pervious support, passing lifting and loosening air currents through substantially all parts of the bed, transversely classifying the particles according to size across the support, by moving 1 the larger particles toward the upper side of the bed and the finer particles toward the lower side of the bed, and subsequently substantially reversing the order of transverse size classification of the particles in the forwardly moving bed by regulating the air action along the bed.

11. A process for concurrently sizing and separating intermixed divided materials the particles of which have a substantial variance in size which comprises progressing a bed of the materials generally forwardly along a transversely inclined, air-pervious support, subjecting the rear portion of the bed to a relatively strong lifting air force and concurrently classifying the particles according to size across the support, subjecting the forward portion of the bed to an air force of reduced lifting power, and substantially reversing the transverse size classification of the particles forwardly of the bed.

12. A process for concurrently sizing and separating intermixed divided materials the particles of which have a substantial variance in size which comprises progressing a bed of the materials generally forwardly along a transversely inclined,

- air-pervious support, subjecting the rear portion of the bed to a relatively strong lifting air force and concurrently classifying the particles according to size across the support by moving the larger particles toward the upper side and the smaller particles toward the lower side of the table respectively, subjecting the forward portion of the bed to an air force of reduced lifting power, and substantially reversing the transverse size classification of the particles forwardly of the bed.

13. A process for concurrently sizing and separating intermixed divided materials the particles of which have a substantial variance in size which comprises progressing a bed of the materials generally forwardly along an air-pervious support, passing lifting and loosening air currents through substantially all parts of the bed, transversely classifying the particles according to size across the support, and subsequently substantially reversing the order of transverse size classification of the particles in the forwardly moving bed by regulating the air action along the bed and concurrently removing heavy settled impurities from the bed.

RICHARD PEALE.

Images