US2001331A - Process and mechanism for separating intermixed divided materials - Google Patents

Description

8 1935. f R. IPEALE, JR 2,001,331

PROCESS AND MECHANISM FOR SEPARATING INTERMIXED D IVIDED MATERIALS Original Filed Sept. 23, 1930 4 Sheets-Sheet 1 I INVENT B MW R. PEALE, JR 2,001,331 PROCESS AND MECHANISM FOR SEPARATING IN TERMIXED DIVIDED MATERIALS May 14, 1935.

Original Filed Sept. 23, 1930 4 Sheets-Sheet 2 May 14, 1935.

R. PE ALE, JR- PROCESS AND MECHANISM FOR SEPARATING INTERMIXED DIVIDED MATERIALS Original Filed Sept. 23, 1930 4 'Shees-Sheet 3 a Cu r.

y 14, 1935- R. PEALE, JR 2,001,331

PROCESS AND MECHANISM FOR SEPARATING INTERMIXED DIVIDED MATEI L IALS Original Filed Sept. 23, 1930 4 Sheets-Sheet 4 9 B ATTORNEY Patented may 14, 1935 UNITED STATES PROCESS AND MECHANISM FOR SEPARAT! ING INTERMIXED DIVIDED MATERIALS Rembrandt Peale, Jr., St. Benedict, Pa., assignor, by mesne assignments, to Peale-Davis Company, Wilmington, ware Del., a corporation of Dela-- Application September 23, 1930, Serial No.

483,856. Renewed September 27, 1934.

Germany December 7 10 Claims.

The invention relates to a novel and useful process and mechanism for separating intermixed divided materials and especially to such a process for purifying unsized coal or the like wherein the pieces and particles vary relatively greatly in size but 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 practice 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 parts, constructions, arrangements, combinations and im-- provements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention. I

Of the drawings: Fig. 1 is a partly diagrammatic side elevation a coal-cleaning table embodying the invention; Fig. 2 is an enlarged, fragmentary, and partially diagrammatic elevation of the rear portion of such a table showing an automatic control system;

Fig. 3 is a fragmentary perspective of the rear end of a cleaning table equippedwith automatic control devices;

Fig. 4 is a fragmentary top plan showing a modified form of the mechanism of Fig. 3;

Fig. 5 is a fragmentary detail, in elevation, of the mechanism shown in Fig. 4;

Fig. 6 is a view similar to Fig. 5, showing a beddepth indicating device;

Fig. '7 is a transverse, vertical section of aseparating deck showing sub-areal chambers;

Fig. 8 is a plan of a deck showing one air-zoning layout;

Fig. 9 is a view similar to Fig. 8 with the pervious deck surface removed;

Fig. 10 is a detail showing vertical sections of a plurality of air-control stoppers; and

Fig. 11 is a top plan of a separating deck.

The invention pertains broadly to the separation of intermixed, divided materials, the term divid d 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 eificiency 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.

One kind of intermixed divided materials which the inventionis 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 necessaryeven 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 crushingor removing the very largest lumps, the practically perfect separation being effected down through the finest dust of the intermixed materials.

In common with other known separating processes, such as those disclosed in prior copending applications of Kenneth Davis, Richard Peale and myself (for example the application of Richard Peale, Ser. No. 389,722, filed August 31, 1929), in the preferred embodiment and practice of the invention a relatively deep bed of the intermixed materials is maintained in substantially continuous progression along a transverse- 1y inclined, air-pervioustable, which is reciprocated, preferably in the directionof its length. Lifting and loosening air currents are passed upwardly through the bed to loosen the particles apart and to effect their stratification by fluidizing the bed, whereby the heavier and lighter materials stratify substantially according to their specific gravities, the heavy impurities gradually and progressively sinking through the unsized, fluidized bed, while the coal is floated and forms a progressively purifying superior stratum. The settled heavy impurities are directed and impelled to the upper side edge of the bed and to discharge therefrom in direct, short and noncumulative paths, substantially as soon as they settle, by a series of transversely-disposed, separating partitions, while the flotant stratum of" coal progresses freely forwardly along the table to discharge at the front end thereof;

In many cases the bed of materials so treated upon the separating table undergoes a concurrent or simultaneous sizing action, whereby the fiotant stratum of coal is classified according to size transversely ofitsdirection of progression, whereby the larger coal pieces gradually work toward the upper and outer side ofthe bed, while the fines congregate along the inner and lower side thereof. One feature of my invention relates to a method and means for effecting complete ultimate purification of all sizes of the coal stratum when the described sizing action occurs.

One of the 'principal objects of my invention sponding variations in the separating forces.

For-example, one of the most frequent and disturbing variations in run-of-mine' coal from a given mine or source is that which occurs-in the moisture content of the coal. In-some mines the seam of coal is alternately dry and wet due to subterranean springs, so that the moisturecontent of the coal may vary greatly almost momentarily. Another factor which varies frequently and has-a great effect upon the separating action, is the relative quantity of fine material in the raw coal. For example, the coal loaded during the morning hours frequently contains a relatively high proportion of fines from the machine cuttings of the previous night, while the afternoon run of coal consists more largely of shot-down coal wherein the proportion of large lumps is greater.

Both the moisture content and the fines content are importantfactors in determining the separating forces required. For example, the air force necessary to adequately stratify a given quantity of coal which is relatively high in moisture and/or fines content, is relatively much greater than the air force for performing the same amount .of work in a bed where the coal is dry and/or the fines content-is. relatively less. Especially when the moisture content is relatively high, the bed will tend to pack and form a cohesive and non-fluidized mass which slides along the table without properly stratifying. Accordingly, the'amount of moisture and/or fines is quite accurately reflected by the relative depth of the bed because when the moisture content or the fines content increases even slightly, the bed willftend to compact and become thicker unless more air force is supplied to stratify it. In some cases, where the-moisture content-in the raw coal becomes excessive, the .bed has. been known to pile up beneath the feed hopper in an immobile.

heap several feet deep. I I

As disclosed in the said application of Richard Peale, Ser. No, 389,722, itisdesirable to control the'amountiand distribution :of .air supplied to thebed of materials onthe Itable lnaccordance with changes in,-the depth of the-bed, and to also alternatively or conjunctively control the amount of material whichisfed tothe bed so as to vary "thefzbed depth and thereby efiectivelyvcontrol the airactions In said application of Richard Peale,

manually operated means are shown forconjunctivlely or independentlycontrolling the air supply and the feed'ofthe material inaccordance with observed changesin the depth of the bed due to variations inthe characteristics of the material.-

My present invention provides an improved I method and mechanism for automatically controlling the separating forces in accordance with changes in the characteristics of the material, particularly as such changes affect the bed depth. Morespecifically,my invention provides means for automatically determining changes in the bed depth, and means for automatically controlling the air supply and distribution and the feed of the materials to automatically vary the separating forces to counteract and take care of such changes. In the present preferred embodiment, I provide a pivoted arm or float which lies on the bed and is responsive to variations in the depth thereof, said float being operatively connected with control mechanisms for the air supply devices and material feeding means, whereby the movements of the float are transmitted to and control the operation of said air supply and feeding means.

It will be understood that the foregoing general descriptionand the following detailed description as-well are'exemplary and explanatory of the inventionbut are not restricted thereon.

Referring now in detail to the embodiment of the invention illustrated by way of example in the accompanying drawings, an air-pervious table or deck I is provided, which is rendered airpervious 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. As shown in Fig. 8, the perviosity of the deck may decrease forwardly in zones a, b, c and. d, although this arrangement may bevaried as desired.

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 are forced upwardly through the bed. As embodied, the walls, 2, .3 and 4 extend downwardly below the table surface and are attached on'their outer sides to a supporting frame I0, which preferably consists of angle beams fastened together at the corners of the table structure. The air-pervious deck I is supported by means of an inner box-like'frame H.

fixed on the inner sides of the retaining walls 2, 3 and 4. A series of longitudinally extending supporting beams l2 divide, the, frame ll longitudinally and serve to support the intermediate portions ofthe deck. The deck is also supported by a series of cross-beams [3, extending transversely of the beams H and serving to divide the space beneath the deck into a plurality of relatively small, mutually isolated sub-chambers Ill. The beams H and I2 rest upon a sub-deck or partition M which is fixed to the bottom edges of the inner frame II. The sub-deck I4 is apertured with a plurality of spaced-apart perforations I5,

and this sub-deck, together with the chambers supporting frame ID of the reciprocable table, I

these arms l6 being pivotally connected to the frame 10 at their upper ends, and at their lower ends are pivotally mounted in the longitudinallydisposed, stationary side members ll ofthe top itself, as will be later described. 7 Therpivotallyconnected supporting arms l6 are upwardly and backwardly inclined, whereby the short reciprocating movement of the table is upward and forward and downward and rearward. In addition,

the 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 suit-- able 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 24 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 21, 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 the frame of the air chamber, and have nuts 30 screw-threaded on their the member 29'. This mechanism servesto pull the table forwardly and upwardly, at the end of the rearward and downwardstrokes' effected by .the reciprocating drive. The springs 21 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 varythe longitudinal inclination of thetable. As embodied, the rear end of the upper frame-work ll of the air chamber is pivotally mounted at 35 on the fixed support 38, while the intermediate and forward portions of the frame are pivotally supported on downwardly extending screw rods 31, which are in turn pivotally mounted on fixed supporting pillars 38. Nuts 39 are screw-threaded on rods 37 and bear against the upper side of the pillars 38. By turning these nuts at the various points along both sides of the structure, the longitudinal inclinations of the table may be 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. '7). 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, S. N. 283,600, filed June '7, 1928.

The embodied means for providing the lifting air currents and for forcing them through the bed of materials comprisesa stationary air chamber 20, which is suspended from a frame of I-beams H. 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-.

' controlled in amount.

ply of air to the table maybe utilized in carrying out the invention-;'-and',' asembodied, comprise.

shrouds or 'veils 50 slidably mounted on tracks 5| at the fan inlet, and variably positionable to regulate theamountzpf air supplied to the fan and thence to-the air chamber 20. Another form of means for varying the entire air supplyto the table, and which may be-used either together with. 7

the fan veils 50 or as a separate and alternative means, comprises an air-regulating valve or shutter device 52, preferably mounted .in the air duct 46 adjacent the flexible. connection 48. The valve member52 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 The individual shutters '53 are preferably mounted for simultaneous open- .ing and closing movement and are operable from thejoutside of the air 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 A currents or cross blasts. forward ends for compressing the springs against A third optional formof means for controlling the general-air supply comprises a-multiple-shutter valve mechanism 55,: which is positioned in the air chamber 20 intermediate the ends 'of the air-pervious deck I. 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 as desired and according to the conditions and requirements of the process.

In the present preferredarrangement of separating partitions upon the surface of the airpervious deck I, all of the separating partitions" are inclined forwardly and outwardly, that is, it

toward the longer or outer and upper side of r the table as shown in Fig. 11, terminating at or near the bed-retaining wall 3. These separating partitions are parallel to each other and preferably extendat an angle totheoblique or diagonal front coal spillage edge 6| of the table,'so as to direct the settled heavier material away therefrom.

The discharge boxes 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 arehere shown more or less conventional-1y. These boxes will be located at proper points along the table, will be connected through variably-sized openings I99 in the bed retaining wall 3, and have the operations and functions described in said application. Likewise as shown in said application, a header 6G is provided above and along side the deck, being supplied withair bylopening 6'! in the side Wall of the air chamber-,having individual flexible air connections 68 with the various refuse discharge boxes 65 and being provided with air current regulating devicesBS.

The regulation of the air-lifting forces in the different parts of the bed may be facilitated and of the air currents can be made very much lower than that formerly used in separating tables such, for instance, as that shown and described in copending application of Richard Peale, Ser. No. 387,397, filed August 21, 1929.

The embodied means for effecting'the desired I 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 multiple shutter valve 'locatedmedian- 1y of the table may be optionally employed to cut down the air supply to the forward portion of thetable 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 55 is not fixed, but may be varied as desired by sliding it along the airchamber on suitable trackways. By virtueiof 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 hereinbefore-de scribed 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, reductions 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. 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 air pressure in the forward portion of the chamber 20.

Still another means for controlling the air cur-,

rents 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 15, 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 The rotatable shutter minimum pressure limits. l5 for creating pulsations in. the air currents is optionally employed with any or all of the hereinbefore described means for controlling the air currents. 7

Means are provided for variably positioning the shutter shaft, comprising spaced apart hub bearings 89 in either side wall of the air chamber 20. The embodied means for rotatably driving the shutter 15 comprises a sprocket wheel 11 keyed to theshaft l6 and drivenby' a chain 18 from the maintabledriveshaft 24.

Referring now to the-"means for flexibly and independently controlling the air' action in rela-' tively small and localizedsub-areas of the bed,

a preferred embodiment thereof is shown in Figs.

7, 9 and IQ. As described, the spacebetween the sub-deck and the upper pervious deck I is sub' divided into a plurality of relatively small and mutually isolated sub-chambers 10 through which the air passes from the main air chamber. shown, the apertures IS in the sub-deck are adapted to receive stoppers H which plug up the apertures and thereby 'control the amount of air supplied to the individual chambers 10.

In accordance with my invention, the-supply of air to the sub-chamber 10 is even more nicely and accurately regulated than heretofore, the

invention providing for varying the amounts of air supplied to different parts of the sub-cham bers and for very finely and accurately controlling the supply of air to any localized area of the deck. As embodied some of the stoppers,

H arethemselves' apertured, as shown in Fig. 10,

being provided with central longitudinal conduits 12 through which air may pass and these conduits maybe of different diameters in difierent stoppers.

By virtue of this construction, it is possible to reduce the amount of air supplied to a subchamber 10 to as small amount as desired, without totally blanking or obstructing passage of air therethrough. In many'cases, it is desirable to admit a relatively very little amount of air to portions of the bed, although a total dead space must beavoided; For example, when a transverse classifying action takes place and the lines congregate along the lower and inner side of the bed, it is desirable to subject these fines to a relatively very low air pressure so as to enhance the settlement of the fine heavy particles. In'

prior structures 'it was difficult to 'obtain the proper air action among the fine'particles because a blanking off of all of the apertures l5 along'the lower side of the deck produced a dead. areain which no separating action or coal flotation could take place.

However, if one ortwo of the apertures l5 were 'left open in each sub-chamber I0,

the air would pass therethroughin a relatively very strong and localized jet, so that asuccession of areas of too great air action would be interspersed with dead spaces. By use of the apertured stoppers H, the amount of air admitted to the sub-chambers along the inner and lower side of the deck may be reduced to as small an'amount as required while thedistribution thereof may be maintained substantially uniform within any given area. ,7

Furthermore, the action of the air throughout any desired portion of the table may be gradated as nicely as desired to supplement or correct the effect of the major zones a, b', c, and din the pervious deck I. to rather radically reduce the air action in the forward portion ofthe bed,particularly forwardly of the end of the inner wall 4. As disclosed in application Ser. No. 389,722, of Richard Peale, filed August 31, 1929 and in our joint application Ser. No. 498,016, filed November 25, 1930 such a drastic lowering "of the air action is desirable to bring the air pressure into the "low pressure range, whereby the established size classifica tion of thebed may be partially or completely For example, it is frequently desirable reversed. The reversal'of the sizing is desirable in many cases in order to automatically cause the fines to work towards the outer sideof the deck, whereby the fine impurities may be more easily discharged.

I have found that it is very difficult to eifec--- tively reduce the air action sufficiently to give the desired size reversal by the use of zones of lowperviosity in the upper deck I alone. The

perforated brass-sheets of-which the deck surpossible to use the standard low-perviosity brass sheeting and still effect the desired reduction in air pressure in the front portion of the bed.

It will 'be understood that the apertures 12 in the stoppers II may be of as many different diameters as desired and that solid stoppers may be used in conjunction therewith when desired.

Referring now to those features of the invention which relate to automatically regulating the air and material supplies according to changes in the depth of the bed of materials on the deck, in the present exemplary embodiment (Figs. 2 to 5) means responsive to variations in the depth of thebed of materials are provided. for automatically controlling the actuation of the fan veils or the air-supply valves, and/or the speedchange mechanism on the feed hopper. As embodied, anarm .or detector-finger I20 is mounted over the air pervious table near the rear end thereof and extends preferably substantially parallel to the side walls, so as to register variations in the depth of the bed above and below a selectively predetermined normal depth and to automatically transmit said variations to the air and feed-control actuating means. As shown in Fig. 3, the upper or rear end of the arm I20 is mounted to rotate with a horizontally-disposed shaft I2I which projects through the side wall 3 of the table and is rotatively trunnioned therein. The

actuating devices, an electrical transmission system is preferably provided, although such transmission could be effected by mechanical, pneumatic or any other suitable means if desired. In the present preferred form, each of the air-supply controls and the feed control may be operated by a small individual, reversible-drive electric motor and each motor is responsive to the movements of the arm I 20; As embodied, the fan veils 50 are suspended by cables I from a hoisting drum I26 mounted on a shaft extending across the top of the fan housing. A reversible motor I28 is mounted adjacent shaft I21 and drives the same to raise and lower the fan 'veils 50 by the worm I29 on the'motor shaft which engages with a ring gear I30 fixed to shaft I21. 4

A similar motor I3I is provided for setting the shutter valve 52. The actuator rod I08 is pivotally connected at its upper end to one end of a bell crank I32. The other end vertically disposed arm of said bell crank comprises a geared segment I33 which engages with worm I34 on the shaft of motor'I3I. a

with. Said drum is provided-with three arcuate The feed hopper. is provided with variablespeed drive for the feed comprising a rotatable; hopper valve mounted on a rotatable shaft 84 near the mouth of the hopper. The shaft 84 is driven froma pulley 85 which is connected by belt to the drive pulley 81: of a Reeves variable speed transmission88, or other-known or suitable variable speedmechanism. The driven pulley 89 of the speed transmission may be connected by'a belt 90 to any suitable power mechanism. For operating thespeed change mechanism for the feed hopper 5, a reversible motor I35 is mounted on the casing 88. Worm I38 on the motor shaft engages with-a pinion gear on shaft 92. 7

Referring now to the embodied means for controlling the operation of the actuating motors I28, I3I and I35 from the movements of the arm I20,

a drum I38 is mounted on shaft I2I to turn thereelectric contact surfaces I40, MI and I42 which correspond to the three motors. Said contacts extend only partly around the drum, which has three similar contact members (notshown) at another part of its periphery for connecting the motors to drive in reverse direction. Separating the two sets or reverse-drive contacts is a neutral insulated zone on the drum. Aset of contact brushes I 45 aremounte'd adjacent the drum to' contact with the periphery thereof and to trans-' mit current therefrom to the motors I28, I3I and I35 by suitable cable connections I46 and I41. It

will be understood that the drum is electrically connected to a suitable source of electric power (not shown) and is wired to effect the desired reversal of the motors. Return or ground contacts I46 for all the motors are also mounted on the drum.

Means are provided for varying the normal setting of the arm I 20 so as toselectively predeter mine the desired normal depth" of the bed. As embodied, the shaft IZI and its attendant mechanism are mounted on a vertically-slidablepanel I50 which may be set at desired levels by pins-or set-screws I5I mounted in the panel guides I52;

2 and 3 is as follows:--The arm I20is' set atthe predetermined height desired and the free end thereof rests on the upper surface of the bed of material which travels forwardly along beneath the arm. So long as the-depth of the bed remains within the limits desired, the insulatedor neutral portion of the drum I38 will contact with the brushes I45 and the motors I28, I3I.and I33 will remain inactive, leaving the air valves and feed drive at their original settings. However, as'soon 'as the depth of the bed increases appreciably, due

toincreased moisture in the ran coal, or other causes, the arm I20 will rise and the contacts on the drum will energize the motors. The setting 5 of the drum contacts and motors is such that the air supply will be increased upon a rising of the bed, while the feed will be conjunctively decreased, if necesary. The increased air pressure will operate to loosen' and stratify the particlesand returnthe bed to normal depth, whereupon the arm I20will drop to normal position and cut off the motors. If, on the other hand, the bed becomes too thin, the arm I20 will swing the The operation of the mechanism shown in Figs.

reverse set of contacts into energizing position and upper and lower limits of travel of the-veil 50 so It will be understood that the control motors .for-the fan veils and the valve 52 are usually not used together, one mechanism usually being a substitute for the other. ;Also, similar control mechanism, manualor automatic, may optionally be provided for any other air valves; pertaining to the table. Furthermore, the control for the feed; mechanism 84 may frequentlybe dispensed with, as in many'ca'ses thechanges'in air supply will be suflicient to keep-the bed at normal desired be desirable to control only the feed mechanism automatically. .For these various selectiveoperations, a central switch box I65 may be provided at any suitable place in the electric cable circuit, wherein there maybe switches. for cutting out any of the motors I28, I3I or I35 as desired, thereby rendering their respective control mechanisms independent. of the depth of the bed.

Instead of a single arm ordetector finger, a number of arms, extending along thebreadth of the table may be employed. The control connections from these arms may be such that all or av substantial number of the arms must be moved in order to change the rate of feed and/or the air supply. In this way, transitory actuation of a single arm by an isolated lump or local accumulation of material will not affect the control, pro-,

videdthe average depth of the bed remains un-- changed. r

As'embodied, (Fig. .4) three'detector arms I10, I" and I12 are positioned at substantially equal intervals across the breadth of the bed near the rear end of the-table. Arm I10 is fixed to shaft I13 to rotate therewith. The shaft is rotatably journalled at I14-in the side wall 4 ofthe tableandextends clear across the width of the table, being rotatably supported with respect to, the other sidewall l. Shaft I13 extends for some distance beyond side wall 3iof the table and has a cam plate I15 fastened to its outer end, the purpose of which will be hereinafter described.

Ann MI is fixed to a rotatable sleeve I16 near the inner end thereof, as by a set screw I11, the

sleeve surrounding shaft I13 and being freely the table and cam disc I18, and a similar cam disc I80 is-keyed to said outer end. Sleeve I19'is J'ournalled in the side wall 3 of the table-for free rotation with respect thereto. -Itwill be understood that shaft I13, sleeve I16 and sleeve I19 as well as their respective arms I10, "I and I12 v are'freely rotatable independently of each other with respect to the table structure.

Cam discs I15. I18 and I80 are substantially identical in essential structure and operation. shownin Fig. 5, disc I18:is roughly circular in outline, having an axially-extending collar I85 which surrounds sleeve I16 and permits the disc to be set in the desired angular position with respect thereto, as by a set screw I86. A pairof electric contacts I81 and I88 are mounted adjacent the periphery of disc I18, said contacts forming the terminalsof a normally openswitch in an electric-circuit connected to the air-control 'will'bring them together. I depth. On the other hand, in some cases it may the switch.

mechanism'of the table. Contacts 101 and m are mounted on uprights I89 and I90 respectively, the lower ends of which are secured ina'suitable insulated bracket I9l, which may be secured to the wall 3 of the-table. The lower ends of the uprights 189 and I90 preferably extend through 1 the insulated supporting member I92 and connect with circuit wires I93 and I94 respectively. Either or both of the uprights are preferablyformed of resilient metal or the like so that the contacts I81 and I88 are normally held apart, butlateral pressure upon arm 1 I90 A cam shoulder I95 is provided on arm I90 for cooperating with a cam surface on the'disc I18. The disc I18 is provided with a camor projection I96 which normally is out of contact wlth shoulder I95. Clockwise movement of the disc will bring cam I96 against shoulder I95 and close A pair of contacts 200 and NI are positioned on the'side'of the disc opposite to contacts I81 and I88 and aremounted and connected in a similar manner, and are adapted to be closed by counter clockwise movement of the disc and the cam I96. 1

Reverting to Fig. 4, circuit wires 205 and 206 i are provided for connection with the reversible motors on the fan veil'control mechanism, the

air control shutter 52 and the motor for-the speed control on the material feedmecham'sm. When electrical contact is established between wires 205 and206, the motors will operate in the proper direction to increase the air supply and/or decrease the feed. A similar pair of circuit wires 201 and 208 are provided for energizing the motors to turn in the reverse direction, to decrease the air currentand/or increase the feed of material.

It will be understood that means are provided for energizing circuit 205'206 when the depth of the bed rises above the normal limit, while an undesirable decrease in bed'depth will actu- =ate mechanism to close circuit 201-208, and that such means, comprising the detector arms HI and I 12 and their associated mechanism, operate in essentially the same manner as the single arm I20 described in connection with Figs. 2 and 3.-

By virtueof the mechanism described in connection with Figs. 4 and '5, circuit 205-206and circuit-201F408 will not be energized unless the are adaptedto be closed by clockwise movements 0.. said respective discs.v

It will be clear that closure of any one or anyv two of said switches will not energize the circuit 205206 but such energization will be effected only when all three switches are closed by simultaneous'olockwise movement of the three cam discs. Consequently it is necessary for all three arms I10, HI and I12 to rise together before the air and/ or feed control motorswill be energized. This prevents energization of said motors by the chance or transitory lifting of a single detector arm,'as by the passage'beneath the arm of a large lump of material projecting above the average lever of the bed.

movement of the cam discs when the detector arms'are lowered.

It will be understood that-the mechanism described in connection with Figs. 4 and 5 isadapted for use in the control mechanism and circuits shown and described in connection with Figs. 2 and 3. Suitable switches may be provided in the circuits for cutting out any one of the control motors, as desired, so that either the feed control, the air control or both, may be rendered independent of the depth of the bed as desired.

In accordance with one feature of myinvention, I provide means for automatically indicating the depth of the bed at all times, and said indicating mechanism may be utilized either in conjunction with the hereinbefore described means for automatically controlling the material feed and/or the air supply and distribution; or automatic bed depth indication maybe provided alone for use without the automatic control devices. In many cases it will be found desirable to have some means for automaticallyindicating the depth of the bed and changes therein when the automatic control means are not provided. For example, when the air supply, including the setting of the veils on the fan, andthe material feed are controlled manually, it is very advantageous for the operator to beable'to ascertain the depth of the bed without going to the table and putting his handin -on the bed of the coal, as is necessary under the previous manual systems, as desoribed'in the copending application of Richard Peale, S. N. 383,122, filed August 31, 1929.

' As embodied, an indicating pointer 250 is mounted for pivotal movement on the outer surface of the side wall 3 of the table, said pointer being fixed to and mounted to turn with the shaft l2! which is actuated by oneor more of the de-' tector arms 'l20. The pointer. 250 is preferably about equal in length to the detector arm whereby the free end 25l of the pointer indicates the actual rise and fall of the detector arm. An arcuate scale 252 may be provided at the end 25l of the pointer with divisions for indicating the depth of the bed in inches or otherwise, If de-.- sired, suitable gearing may be provided for am plifying the movement of the pointer arm so as to indicate the changes in bed depth on a greater scale.

If desired, means may be provided fortrans- .mitting the indications'ofbed depth to remote points. For example, flexible shafts may be provided for transmitting the movement of the pointer to indicators stationed near the feed control mechanism and the fan, whereby theoperator can ascertain the depthof the bed without leav-' ing his station at these mechanisms. Generally, however, it will be found that y'isualindicating means of the type shown iii-Fig. 6 will'be sufiicient for all practical purposes.

Referring now to Fig. 11, my invention provides a novel method and mechanism for enhancing the ultimate purification of all sizesof the coal in the bed, especially when a transverse size classification thereof takes place concurrently with'the separating action. This feature of my invention relates to the extraction and retreatand which contains coal and impure materials vides voids inthe bed into which table, whe'reb in partial intermixture. As embodied, the coaldischarge chute 300 is shown provided with a division forming a middlings .chute 3M disposed adjacent theforward and outer tip ofthe .table for receiving and separately discharging a selected middlings product delivered at said portion of the table The middlings product delivered to the chute 30l usually consistsof some few relatively very coarse coal pieces directed toward the outer side of the bed by thesimultaneous action, intermixed .with very fine heavy impurities which have escaped dischargethrough therefuse boxes 65 and a considerable amount of low-gravity refuse of different sizes, consisting principally of pieces of bone" and agglomerated coal and rock.

By my invention, I provide for making a midd1ings"cut at one or more other sections of the discharging coal stream, preferably adjacent that section of said stream where the fine particles congregate and are discharged. In some cases, particularly with coals containing a relatively large proportion of very dirty fines, the simultaneous sizing action inthe bed causes much of the fine refuse to work toward the inner and lower side of the tablewith the fine coal. As the fine material congregates and travels along the lower side of the bed, thefine heavy particles will gradually and progressively settle to the bottom. However, after settling, these fine heavy particles must travel along the separating partitions substantially the full width of the deck thermore, some fine particles of refuse which do settle, and travel along the separating partitions forsome distancemay be again floated into the upper strata by the air action as they travel toward the outer side of the deck. This re-fioating and remixture of the fine refuse is attributable to the fact that the presence of the coarser coal particles in the outer portion of is blown by the rising air currents. Consequently,

- with some coals an appreciable quantity of fine refuse may be dischargedwith the coal atan intermediatesection of the coal spillage edge 6|. IBy my invention I provide means for extractingafrel'atively impure section of the coal stream, suchas one containing inte'rmixed,ffine particles the deck prothe fine refusefor the jrea'sons described. As shown in Fig. 11,

anxauxiliary'middlings chute IBM-is provided intermediate-ihe'sides, of the discharging coal streamand relatively near the lower side of the y. a middlings cut may be made of I dlings, i. e., coal containing intermixed fine refuse. As shown, the chute 302 is formed by walls iilw and 3M, disposed diagonally on the surfac-dfcoal chute 300. The middlings chute 3021s provided with means for selectively varying the amount of fine middlings extracted, and for also selectively varying the location of the extraction point so as to-allocate the fine middlings out according tov the location in the coal stream of the entrained fine refuse particles. As embodied, the sides 303 and 304 are provided with independently angularly movable vanes 305 and 306, respectively, which may be swung laterally for the purposes described. Similarly, the regular middlings chute 3M is provided with a transversely positionable pivoted vane 30'! for conthe fine mi bed to undergo asecond separating action.

The invention in its" broader aspects is not lim-' ited to the specific mechanisms shown and described but departures may be madetherefrom within the scope of the accompanying claims without departing from the principles of the in-'- vention and without sacrificing its chief advantages. -l.

I claim:

v 1. In a mechanism for separating intermixed divided materials including in combination an air-pervious deck, an air chamber, a member in the chamber below the deck containing a pluraiity of aperaures for admitting air to the deck and means for controlling passage of air through said apertures comprising apertured stoppers. 2.. In a mechanism for separating intermixed divided materials including in combination an air-pervious deck, an air chamber, a member in the chamber below the deck containingaplurality of apertures for admitting air to the deck and means for controlling passage of air through said apertures comprising a plurality of stoppers having apertures of different sizes. p

3. In a mechanism for seperating intermixed divided materials including in combination an air-pervious deck,a member having a plurality of apertures for admitting air thereto, and means for controlling the passage of air through said apertures comprising a plurality of stoppers adapted to fit into .and partially obstruct the apertures. I r

4. In a mechanism for separating intermixed divided materials including in combination an air chamber, a member having a plurality of.

apertures mounted in the chamber, anda plurality of stoppers adapted to fit into the aper-- tures, said stoppers h'avingopenings therein for admitting a limited amount of air through the apertures, said openings being of different size in different stoppers. j

The process of purifying coal which comprises subjecting a substantial bed of raw coal to, vibration and'lifting andloosening air currents to stratify and separate the coal and heavy impurities, progressing the flotant coal stratum to discharge and concurrently effecting a transverse size classlflcation thereof, extracting middlings from the coarsecoal 'and separately extracting middlings from the fine coal.

6; The process of purifying coal which comprises subjecting a substantial bed of raw coal to vibration and lifting and loosening air currents to stratify and separate the coal and heavy impurities, progressing the flotant coal stratum to discharge and concurrently effecting a transverse size classification thereof, extracting a setrolling theamount of middlings cut from the lected portion of the coarser coal in the discharging coal stream as middlings and'extracting finer middlings from another portion of said stream, and returning the middllngs to the bed for additional separating action.

'7. A mechanism for separating intermixed divided materials including in combinationlan airpervious table, means for, maintaining a continuous, traveling bed of raw. coal thereon undergoing stratification and separation, means for dis-- charging the coal as'a flotant, transversely sized stratum, means for impelling settled. heavier inaterial transversely of the flotant stratum to discharge, means for removing a middlings product from the coarse coal and means for removing a middlings product from the fine coal.

8. Mechanism for separating intermixed divided materialsincluding in combination an airpervious deck, means for maintaining thereon a traveling bed of raw material undergoing pneumatic Stratification and separation including a mechanically-actuated feeder for regulably supplyingraw materials to ,the deck, a member con tacting with the surface of the bed on the deck and movable in conformity to changes in the depth of the bed, and devices controlled by said member for regulating the feeder thereby to vary the supply of raw material to the bed in accordance with variations in depth thereof.

9. Mechanism for separating intermixed divided materials including in combination an airpervious deck. means for maintaining thereon a traveling bed of raw material undergoing pneumatic Stratification and separation including a mechanically-actuated feeder for regulably supand movable in conformity to'changes in the depth of the bed, and devices controlled by said member for regulating the feeder thereby to vary the supply of raw material to the bed in accordance with variations in depth thereof, a motordriven fan for supplying air under pressure to the bed, a regulatingdevice for-varying the amount of air supplied by the fan, and devices controlled by said member for actuating the fan regulating device.

10. Mechanism for separating intermixed divided materials including in combination an air-'- pervious deck, means for maintaining thereon a traveling bed of raw material undergoing pneumatic stratification and separation including a mechanically-actuated feederfor regulably supplying raw materials to the deck, a member contacting with the surface of the bed on the deck and movable in.- conformity to changes in the.

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