US2889045A - Apparatus for washing coal and ore - Google Patents

Description

June 2, 1959 J. TURPIN 2,889,045

APPARATUS FOR WASHING COAL AND ORE Filed March 4, 1955 4 Sheets-Sheet 1 INVENT OR JACQUES TURPI N ATTORNEYS June 2, 1959 J; TURPIN APPARATUS FOR WASHING COAL AND ORE Filed March 4, 1955 4 Sheets-Sheet 2 FIG. 3.

INVENTOR JAcouEs- TuRPm ATTORNEYS June 2, 1959 J. TURPIN APPARATUS FOR WASHING COAL AND ORE 4 Sheets-Sheet 3 Filed March 4, 1955 INVENTOR JACQUES TU RP'I N M *W ATTORNEYS June 2, 1959 J. TURPIN 2,889,045

APPARATUS FOR WASHING COAL AND ORE.

Filed March 4, 1955 4 Shets-Sheet 4 IN VENT OR .moouas TURPIN 34m #M ATTORNEYS United States Patent ()fice Patented June: 2, 1959 2,889,045 APPARATUS FOR WASHINGCOAL AND ORE Jacques Turpin, Fontaihebleauplirance, assignor tosocit lfreparation Industrielle des Coinbustibles; .Fontainebleau', France This invention relates to apparatus and processes for Washinggranular mineral material such as coal and ore andthe like and has more particularreference to such apparatus and processes involving the den'simetric classing'of the granular material in a fluid medium submitted to pulsations and the separate removal of the light'and heavy products.

Apparatus and processes for washing coal, ore, and the like; by means of densimetric classing in a fluid medium submitted to pulsations, wherein the discharge of heavy products is automatically adjusted in relation to the weight of the washing bed, are well known. In such apparatus and processes the'productsto becleaned pass into one or several washing compartments upon perforated plates, sometimes covered with a layer of feldspar or the'like. The densimetric classiug, the progression and discharge of the products being Washed being obtained by means of water pulsations through the perforated plates, pulsations which lift the'washingbed, causing, when it falls back; its separation into heavy and light products with, often, one or several intermediatecategories. The pulsations are made either by means of pistons or through the action of compressed air upon the free surface of the Water; into compartments adjacent to the washing ones.

The automatic discharge of the heavy constituents of theraw product is, in the majority of cases, regulated in each compartment by means of an immersed float, either in a tube running across the washing bed or in the wash ing bed itself. The floats movementsregu'late, in either case, through the intermediary of suitabledevices, the discharge of 'heavyproducts in relation to the'weight of thewashing bed.

In such apparatus, quantitative orqualitativevariations of the automatic regulating system resultin' its defective operation. In fact, these apparatus are constructed and adjusted to treat'an output varyingibetweenceitain given limits which, as far as'unitsoperating correctly are concerned, must not be too widely exceeded. In the same way, the quality of the raw product, although subject to variations, must not differ too widely from an average composition, corresponding to the optimumoperation of the units. Accordingly, whenever there'is too weak an output of the raw products or a too weak quantity of heavy products in the material being treated, the washing bed becomes too light, resulting in the densimetric classing being incorrectly affected so that light products are discharged together with heavy ones and vice versa.

The primary object of the present invention is to provide a novel method of and improved apparatus for overcoming these drawbacks or defects.

Another object of the present invention is to provide a novel method of and improved apparatus for jig washing granular mineral products such as coal and ore, orthe like, wherein means are provided for recycling the whole or part of the heavy productsdischarged from one or all of" the Washing beds so as to replace the recycledheavy products in front of min a suitable'point of one or=more of the-washingibeds,

the recycliirgiof the'heavy products 2 being automatically eirected in relation to the amount of heavy products present in the washing bed.

Another objectof the present invention is' to provide improved jig washing apparatus, as characterized above; wherein the means for recycling the discharged heavy products includes a valve member controlled by the op eration of the device employedin detectingthearnount of heavy products inthe washing bed or beds into which the diverted portion of'the discharged heavy products is being recycled.

Other objects and advantages of the invention will appear in the following specification when considered-in connection with the'accompanying drawings, wherein:

Fig. 1 is a. diagrammatic elevational view, partly in cross section, of one embodiment of apparatus constructed in accordance withthe present invention for carrying out the method of the invention;

Fig. 2 is a vertical sectional view taken on the line 2 2 ofFi'g. 1;

Fig. -3'is a diagrammatic view showing an electric system of automatic drive for controlling the replacement of the heavy products in the apparatusg Fig. 4 is a diagrammatic'view showing the circuits connecting the relay to thelink switch;

Fig. Sis a diagrammatic view, partly in transverse cross section; of amodified form of apparatus employing hydraulic mean'sfor controlling 'the recycling of the heavy product;

Fig. l 6 is a diagrammatic elevational view, partly in cross section, of the hydraulic apparatus shown in Fig. 5;

7 isa detail-'viewofthe valve shown in" Fig; 5; and

Fig. 8"is a diagrammatic elevational view," partly in cross section, of anotherform of hydraulic apparatus for controllingthe recycling of the heavy product.

In general, the present invention provides anovel process of and improved apparatus for jig washing coal, ore, and the like, by means of densinietr'ic classing ina fluidmedium submitted to pulsation, wherein automaticmeans are provided for maintaining a predetermined quantity of heavy. products in the washing bed orbedsby diverting and recycling a'portion ofthe discharged heavy products from the bed or beds back into the bed-or beds in response to the amount of heavy products present inthe bed or beds.

Referringznow to the drawings, there is diagrammatica'lly shown, inFi'gs. 1, 2 and 3, one embodiment of apparatus for carrying out the process of the present invention.

As there shown, the jig comprises a tank or'vat 10 provided with a plurality of washin'gboxes or compartments 11; each having a washingtable 12 mounted therein*an'deach being in communication with an adjoining pulsation compartment '13 provided with a pulsating device indicated generally at 14, forpulsatingthe water? in" the washing box up and down through the washing table, a plurality of drain elevators 15, a plurality of evacuation pipes16, one'connecting the bottom of each washing box withone of the drain elevators for removing the heavy product; one ormore recyclinglconduits 17, each having its inlet end in communication with one of the drain elevators and its outlet endpositioned to discharge onto the washing table in oneof the washing boxes; valve means, indicated generally at 18, associated with the inlet end of each oftherecyclingconduits 17 for controlling the amount of heavy products diverted into the recycling conduit; a plurality of-detecting means, indicated generally: at19, one associated with each washing box for de-' tecting the amount of heavy products presentin' the box and controlling thepulsating means forthe box; and control' means, indicated generally at 20 each connected to contr'ol the-operation of one ofthe valve means ls itt one of the drain elevators in response to actuation by one of the detecting means 19 in one of the washing boxes.

The products to be treated enter the jig by means of inlet chute 21 and are classified in the washing boxes, by the up and down motion of the pulsating water passing through the washing tables in the washing boxes, into densirnetric layers with the heavier products forming the bottom layers and the lighter products forming the top layers.

The products travel longitudinally through the vat, passing over sills 22 separating the washing boxes and in each washing box the heavy products are discharged through the beds and the perforated plates which form the washing tables, and leave the vat through the evacuation pipes 16 and drain elevators 15.

The pulsations of the water in each of the washing boxes is controlled by means of compressed air entering the pulsating compartment through a suitable valve 23,

alternately connecting the compartment to a compressed 7 air manifold 23' connected to a source of compressed air (not shown) or to the atmosphere.

The detecting device 19 in each wash box controls air which flows through the valve 23 associated with the pulsating compartment communicating with the wash box through suitable mechanism (not shown).

The valve means 18 associated with the drain elevators 15 are identical in construction and, as shown in Figs. 2 and 3, each comprises a shutter 24 pivotally mounted in the drain elevator at the junction of the recycling conduit therewith and mounted to be moved from a closed position closing the inlet to the recycling conduit, to an open position closing the discharge opening from the drain elevator (see Figs. 2 and 3).

In this particular embodiment of the invention, the control means for actuating the shutter 24 in the drain elevators are identical in construction and, as shown in Fig. 3, each comprises a motor 25, reduction gearing 26 connected to the motor and carrying a pinion gear 27 engaging a segmented gear 28 secured to the axle of the shutter 24 for movement thereof, a relay 29 for controlling the direction of rotation of the motor and having a circuit connected thereto including limit switches 30, 31 positioned to be closed by a depending arm 32 of the shutter 24 when it reaches the limit of its two positions to stop the motor, and a circuit connected thereto including limit switches 33, 34 for starting the motor; a hydraulic cylinder 35 having a piston 36 mounted therein on a stem 37, the upper end of which projects from the cylinder and carries an arm 38 positioned to close the limit switches 33 and 34 as the piston moves up and down in the cylinder, the lower end of the stem 37 projects through the bottom of the cylinder 35 and carries a taper valve 39 which assists in regulating the pressure of the air in the pulsating compartment; a hydraulic feed cylinder 40 having a stem 41 carrying vertically spaced pistons 42, 43 slidably mounted therein, with the lower end of the stem projecting through the bottom of the cylinder; oil pipes 44, 45 connecting the upper and lower portions respectively of the cylinders 35 and 40; an oil tank 46; a compression pump 47 having its discharge side connected through a pipe 48 to the intermediate portion of the cylinder 40; and evacuation pipes 49 and 50 connected to the top and bottom of the cylinder 40 and to pipe line 51 for evacuating the oil therefrom into tank 46.

The up and down movement of the stem 41 and pistons 42, 43 in the cylinder 40 is controlled by the detecting device 19 associated therewith. And, as shown in Fig. 3, the detecting device comprises a float 52 connected to a vertical rod 53 slidably mounted on suitable supports fixedly attached to the jig frame and with its upper end connected to a driving eyelet 54 carried by the bottom of the stem 41.

The operation of the device is as follows:

The hydraulic fluid put under pressure by the pump .47 enters the feed cylinder 40 through pipe 48. A downward movement of the float 52 moves the piston valves 42, 43 downward in the cylinder 40, permitting oil under pressure to flow through pipe 45 into the lower portion of cylinder 35, pushing the piston 36 therein upward, causing arm 38 to close limit switch 33, which, operating through relay 29, starts the motor 25 to move the shutter 24 in a direction to open the inlet opening into the recycling chute 17 connected to the drain elevator 15 associated therewith, thereby starting the flow of heavy products through recycling chute 15. As soon as the shutter 24 reaches its full open position, shown in dotted lines in Fig. 3, it closes limit switch 31 to stop the motor. As the piston 36 moves upwardly in cylinder 35, the oil above the piston is forced through pipe 44 into feed cylinder and through pipes 49 and 51 back into the tank 46.

An upward movement of the float 52 moves the piston valves 42, 43 upwardly in cylinder 40, permitting the oil under pressure to flow through pipe 44 into the upper portion of cylinder 35, pushing the piston 36 therein downward, causing arm 38 to close limit switch 34, which, operating through relay 29, starts the motor 25 to move the shutter 24 in a direction to close the inlet opening into the recycling chute 17, to thereby cut off the recycling of the heavy products. As soon as the shutter reaches its closed position, as indicated in full lines in Fig. 3, it closes the limit switch 30 to stop the motor. As the piston 36 moves downward in the cylinder 35, the oil below the piston is forced through pipe into feed cylinder 40 and through pipes and 51 back into the tank 46.

This electro-servo driving system for operating the shutter 24 is an all or nothing process. As the shutter 24 is always in its closed position or in its open position, the amount of products diverted from the drain elevator into the recycling chute is all or nothing.

The electric diagram illustrated in Fig. 4, shows the general arrangement of the relays in the relay box 29.

In Figs. 5, 6 and 7, there is shown a jig 10' generally similar to the jig shown in Fig. l, but provided with a modified form of detecting device, indicated generally at 19', and a modified form of control device, indicated gen- 4 erally at 20, for controlling the operation of the shutter valve 24' in the drain elevator 15' to divert the heavy products into the recycling chute 17 In this particular embodiment, each of the detecting devices 19 is identical in construction and, as shown,

.- 7 each comprises a float 52' connected to a vertical rod 53' slidably mounted in suitable supports fixedly attached to the jig frame and with its upper end pivotally connected to the lower end of a rod 55 which, in turn, has its upper. end pivotally connected to one end of a lever 56 having its fulcrum 57 mounted on a support fixedly attached to the jig frame. The other end of the lever 56 is connected to control device 20' in a manner hereinafter to be explained.

The control devices 20' are identical in construction 1 and, as shown in Fig. 6, each comprises a cylinder 58 mounted on a support fixedly attached to the jig frame and having a piston 59 slidably mounted therein and having an upstanding stem 60 pivotally connected adjacent its upper end in a slot formed in one end of a lever 61, which has its other end pivotally mounted on a support fixedly secured to the jig frame; a cable 62 having one end secured to the upper end of the stem 60 and its other end secured to an arm 63 fixedly connected to the axle of the shutter 24', the arm 63 being provided with a balancing counterweight 64; a coiled compression spring 65 mounted on the piston stem 60 for normally forcing the piston downwardly in the cylinder; a feeder hydraulic cylinder 66 having an integral vertical rod 67 on its upper end pivotally connected to the lever 61 in-,

termediate the ends thereof for interlocking the cylinder .ylinder 66, with the lower end portion of the rod projecting through the bottom of the cylinder and pivotally connected to one end of the lever 56 of the detecting device; a flexible pipe 71 connecting the bottom of the cylinder 58 to the intermediate portion of feeder cylinder 66; an oil tank 46 having a flexible evacuation pipe 72 connecting the bottom portion of cylinder 66 thereto; and a pressure pump 47 having its suction connected to the tank 46 and its discharge connected to a flexible pipe 73 which is connected to the upper end portion of cylinder 66.

The thicknesses of the piston valves 69 and 70 are such, relative to the diameters of the inlet openings to the pipes 72 and 73, and the valves are so positioned relative thereto, that normally they close the inlet openings to the pipes 72 and 73 until moved out of closing position 'by movement of the float 52 and at no time will oil be admitted to the cylinder 66 above the upper piston valve 70 .or below the lower piston valve 69.

The operation of the device is as follows I The hydraulic fluid put under 47 enters the feed cylinder 66 through flexible pipe 73. A downward movement of the float 52'. moves the piston valves .69, 7-0 upwardly in feed cylinder 66, opening the inlet of pipe line 73 while the inlet of pipe line 72 remains closed thereby permitting oil under pressure to pass through flexible pipe 71 into the bottom of cylinder 58, pushing piston 59 upwardly against the downward pressure of coiled spring 65. The upward movement of piston 59 permits the counterweight 64 on the arm 63 to move the shutter 24' toward its full open position to thereby divert the heavy products into the recycling chute 17 Also, as the piston 59 moves upwardly, its stem 60 will swing the lever 61 about its fixed pivot, thereby raising the feed cylinder 66 until the upper piston valve 70 closes the outlet of the oil pipe 73, the piston valve 69 maintaining the inlet opening in pipe line 72 closed during the foregoing movement. This results in a balancing of the oil pressure in the cylinder 58 on the piston 59 with the pressure exerted on the piston by the spring 65 and the shutter will be held in equilibrium in partially open position corresponding to the particular position of the float 52. Any further downward movement of the float resulting in a corresponding further opening of the shutter,

An upward movement of the float 52' moves the piston valves 69, 70 downwardly in feed cylinder 66, opening the inlet of pipe line 72 while the inlet of pipe line 73 remains closed thereby permitting the oil in cylinder 58 to be pushed by the pressure of the spring 65 on piston 59 through pipe 71 into the feed cylinder 66 and through evacuation pipe 72 into tank 46. As the piston 59 moves downwardly, stem 60 acting through lever 61, will lower the feed cylinder 66 until the lower piston valve 69 closes the inlet of pipe 72, the piston valve 70 maintaining the inlet opening in pipe line 73 closed during the foregoing movement and the pressures on the piston 59 are again brought into balance. When the float is in its high position the shutter 24 is entirely closed.

This device is called proportional because each position of the float determines one position of the shutter.

In Fig. 8 there is shown another modified form of hydraulic mechanism for operation of the shutter 24" to move it from a closed position, which prevents any of the heavy products from entering the recycling conduit, to an open position which efiects the diversion of all of the heavy products into the recycling conduit.

In this particular modification, each of the detecting devices 19" are identical in construction and, as shown in Fig. 8, each comprises a float 52 connected to a vertical rod 53" slidably mounted on suitable supports fixedly attached to the jig frame and with its upper end connected through driving eyelet 54' to the control device 28".

pressure by the pump is slidably mounted in the pipe 89 and enters the upper The control devices 20 are identicalin construction and, as shown in Fig. 8, each comprises a hydraulic cylinder 74 having a piston 75 slidably mounted. therein with its upstanding stem projecting through the top of the cylinder and pivotally connected at its upper end to the slotted outer end of an arm 76 fixedly secured to the axle of the shutter 24 for rotating it to and from its closed and open positions; a pair of vertically spaced hydraulic cylinders 77, 78 having a common stem '79 extending into each cylinder and carrying a spaced pair of vertical piston valves 80, 81 on its upper endportion', which are slidably mounted in the upper main feed cylinder 77, and a single piston 82 on its lower end which lower auxiliary cylinder 78; a stem 84 extending downwardly through the bottom of the cylinder with its lower end carrying an eyelet 54 connected to the upper .end of the float rod 53', and carrying on its upper end portion a pair of vertically spaced piston valves 85, 86 slidably mounted in the pilot cylinder; a pair of pipes 87, 88 connecting the upper and lower end portions, respectiv ly, of the cylinders 74 and 77; a pipe 89 connecting the upper end portion of the cylinder 78 to pipe 88; a pipe 90 connecting the lower end portion of cylinder 7.8 to pipe .87; a pair of pipes 91, 912 connecting the upper and lower end portions, respectively, of cylinders 78 and 83; a tank 93; a pressure pump 94 having its suction end connected to tank 93 and its discharge end connected to pipe 95 which is connected to the intermediate portion of the pilot cylinder 83; a pipe 96 connecting pipe 95 to the intermediate portion of the feeder cylinder 77 an evacuation pipe 97 connected to the tank 93 land to branch pipes 98, 99, which, in turn, are connected to the upper and lower ends, respectively, of feeder cylinder 77 and an evacuation pipe connected to the tank 93 and to branch pipes 101, 102, which, in turn, are connected to the upper and lower ends, respectively, of the pilot cylinder 83.

The operation of the device is as follows:

The hydraulic fluid put under pressure by the pump 94 enters the pilot cylinder 83 through pipe 95 and the feed cylinder 77 through pipe 96. A downward movement of the float 52" moves the piston valves 85, 86 downwardly in the pilot cylinder 83 permitting oil under pressure to pass through pipe 92 into the bottom of the auxiliary cylinder 78, pushing piston 82 upward which, through common stem 79, moves the piston valves 80, 81 in the feed cylinder 77 upward, thereby permitting oil under pressure to pass from the feed cylinder 77 through pipe 87 into the top of cylinder 74, where it pushes the piston 75 downward to move, by means of the piston stem and arm 76, the shutter 24" to its open position. At the same time, oil under pressure passes from the cylinder 78 through pipe 90 into pipe 87 and into the top of the cylinder 74.

As piston 75 moves downward, the oil in the cylinder 74 below the piston 75 is pushed through pipe 88 into the bottom portion of feed cylinder 77 and from there through pipes 99 and 97 back into tank 93. A portion of the oil flowing through pipe 88 is diverted through portion of the auxiliary cylinder 78, and from there flows through pipe 91 into the upper portion of pilot cylinder 83 and from there flows through pipes 101 and 100 into the tank 93. Thus, a very small oil feed in the pilot cylinder completely opens the shutter 24.

An upward movement of the float 52 moves the piston valves 85, 86 upwardly in the pilot cylinder 83, permitting oil under pressure to pass through pipe 91 into the top of the auxiliary cylinder 78, pushing piston 82 downward which, through common stem 79, moves the piston valves 80, 81 in the feed cylinder 77 downward, thereby permitting oil under pressure to pass from the feed cylinder through pipe 88 into the bottom of cylinder 74, where it pushes the piston 75 upward to move the shutter 24" to its closed position. At the same time, oil

a pilot cylinder 83 having by said detecting means under pressure passes from the auxiliary cylinder 78 through pipe 89 into pipe 88 and into the bottom of cylinder 7 4.

As piston 75 moves upward, the oil in the cylinder 74 above the piston 75 is pushed through pipe 87 into the top of feed cylinder 77 and from there through pipes 98 and 97 back into tank 93. A portion of the oil flowing through pipe 87 is diverted through pipe 90 and enters the lower portion of the auxiliary cylinder 78 and from there flows through pipe 92 into the lower portion of the pilot cylinder 83, and from there through pipes 102 and 100 into the tank 93.

This hydraulic driving system for operating the shutter 24" is an all or nothin process. As the shutter 24" is always in its closed position or in its open position, the amount of products diverted from the drain elevator into the recycling chute is all or nothing.

From the foregoing, it readily will be seen that there has been provided a novel method and improved ap- V paratus for jig washing coal, ore and similar solid products; apparatus which comprises one or more washing compartments each having an evacuation conduit for removing the heavy products discharged from the washing bed; a recycling conduit connected to the evacuation conduit for recycling all or a portion of the heavy products back into the bed; and a pressure responsive detecting device actuated by the amount of heavy products present in the bed for controlling the amount of heavy products to be diverted and recycled; whereby a sufficient quantity of heavy products will be maintained in each bed to prevent the discharge therefrom of light products which would become misclassified due to lack of heavy products in the bed.

Obviously, the invention is not restricted to the particular embodiments thereof herein shown and described.

What is claimed is:

1. In a jig for washing coal, of the type comprising a wash box having a washing table therein for supporting a bed of materials adapted to be acted upon by a body of washing liquid, and means for producing a pulsating flow of the washing liquid through said bed of materials for densirnetrically classifying the materials; the improvement which comprises means including an evacuation conduit for removing the heavy products dischanged from said bed of materials; a recycling conduit having its inlet end connected to communicate with said evacuation conduit and its outlet end positioned to discharge the recycled products passing therethrough back into said bed of materials; .a valve member associated with the inlet opening of said recycling conduit; means for operating said valve member for regulating the passage of products through said recycling conduit including motive means connected to move said valve from closed position to open position and from open position to closed position and hydraulic means for controlling the operation of said motive means; and detecting means including a float positioned in said bed of materials and movable up and down therein in response to variations in the amount of heavy products in said bed of materials for actuating said hydraulic means \so that the valve will be regulated in response to variations in the amount of heavy products in said bed and thereby control the rate of recycling products through said recycling conduit,

2. Apparatus as set forth in claim 1, wherein said motive means includes an electric motor connected to move said valve from closed position to open position and from open position to closed position; limit switches connected to stop said motor when said valve has reached its opened position and its closed position; and a relay for starting the motor in either direction; and wherein said hydraulic means includes a hydraulic device actuated for controlling the operation of said relay.

3. Apparatus as set forth in claim 1, wherein said motive means includes a drive cylinder having a piston therein connected to move said valve from open to closed position and from closed position to open position as said piston moves in alternate directions in said cylinder; and wherein said hydraulic means includes a feed cylinder having piston valves therein for controlling the flow of hydraulic fluid under pressure to and from said drive cylinder and a pilot cylinder actuated by said detecting means for controlling the movement of the valve in said feed cylinder.

4. Apparatus as set forth in claim 1, wherein said motive means includes a drive cylinder having a piston therein connected to actuate said valve, and spring means for moving said piston in one direction; wherein said hydraulic means includes a hydraulic feed cylinder having piston valves therein for controlling the flow of a hydraulic fluid to and from the bottom end of said drive cylinder for moving the piston therein in the opposite direction, said last named piston valves being connected to be actuated by said detecting means; and wherein means are provided for interlocking said feed cylinder and the piston in said drive cylinder including a lever having one end pivotally mounted on the jig frame and its other end portion connected to said feed cylinder and said piston, the construction and arrangement being such that the control device will maintain said valve in a position corresponding to the position of the float of the detecting means, whereby the valve will be opened to permit the recycling of heavy products as called for by the particular position of the float as determined by the :amount'of heavy products in said bed.

5. In a jig for washing coal, of the type comprising an elongated vat having a plurality of liquid washing compartme nts formed therein, each having a washing table for supporting a bed of materials adapted to be acted upon by a body of washing liquid, and means for pro ducing a pulsating flow of the washing liquid through the bed of materials therein for densirnetrically classifying the materials; the improvement which comprises means associated with each of said washing compartments for recycling a portion of the heavy products discharged from the bed of materials therein back into the bed of materials in response to the amount of heavy materials in the bed, said means including an evacuation conduit for removing the heavy products discharged from the bed of materials in the washing compartment; 2. recycling conduit having its inlet end connected to communicate with said evacuation conduit and its outlet end positioned to discharge the recycled products passing therethrough back into the bed of materials; a valve member associated with the inlet opening of said recycling conduits; means for operating said valve member for regulating the passage of products through said recycling conduit including motor means connected to move said valve from closed position to open position and from open position to closed position and hydraulic means for controlling the operation of said motive means; and detecting meansineluding a float positioned in the bed of materials and movable up and down therein in response to variations in the amount of heavy products in the bed for actuating said hydnaulic means so that the valve will be regulated in response to variations in the amount of heavy products in the bed and thereby control the rate of recycling products through the recycling conduit. 1

References Cited in the file of this patent UNITED STATES PATENTS 2,694,490 Harvengt Nov. 16, 19 54 FOREIGN PATENTS 301,812 France Dec. 3, 1928

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