US3042207A - Ore concentrator - Google Patents

Description

5 Sheets-Sheet 1 .mv 5 F EQ k r 2 "NW w 3 wt veg July 3, 1962 E. F. GOBATTI ORE CONCENTRATOR Original Filed Sept. 26, 1958 INVENTOR ATTORNEY EDMOND F GOBATT/ BY Peas/w J Ebro/1 July 3, 1962 E. F; GOBATTl ORE CONCENTRATOR Original Filed Sept. 26, 1958 5 Sheets-Sheet 2 INVENTOR EDMOND F GOBATT/ BY R0552?" Li QQTC ATTORNEY July 3, 1962 E. F. GOBATTI 3,042,

ORE CONCENTRATOR Original Filed Sept. 26, 1958 5 Sheets-Sheet 3 INVENTOR EDMOND F GOBATT/ BY ROBERT (J P/JTcH ATTORNEY ORE CONCENTRATOR Original Filed Sept. 26, 1958 5 Sheets-Sheet 4 INVENTOR EDMOND 608,477!

9055;? Herc ATTORNEY July 3, 1962 E. F. GOBATTI ORE CONCENTRATOR 5 Sheets-Sheet 5 Original Filed Sept. 26. 1958 R mn WT A M@ G P w 0 M E BY ROBERT (J. PATCH ATTORNEY United States Parent 3,042,207 ORE CONCENTRATOR Edmond F. Gobatti, Rte. 3, Box 252A, Pueblo, Colo. Original application Sept. 26, 1958, Ser. No. 763,667, new Patent No. 2,989,184, dated June 20, 1961. Divided and this application Oct. 6, 1960, Ser. No. 64,676

4 Claims. (Cl. 209-433) This application is a division of copending application Serial No. 763,667, filed September 26, 1958, now Patent No. 2,989,184, dated June 20, 1961.

The present invention relates to a concentrator, and more particularly to a concentrator of the reciprocating sluice trough type.

In the separation of materials of various particle weights and sizes, it is common practice to concentrate an aqueous slurry of the material by feeding it to an elongated box or trough having a plurality of longitudinally spaced obstacles over which the slurry passes. The trough is reciprocated lengthwise and the water and lighter particles tend to pass over the obstacles while the heavy particles tend to be left behind in the bottom of the trough.

For example, in ore dressing operations, ground ore is frequently fed to such a trough along with water. The trough is provided with transverse partitions known as riflies, and as the trough is reciprocated the concentrates tend to collect in the compartments between the riffies while the lighter 'middlings and tailings or gangue pass over the riflies to further compartments.

Finally, the tailings and water leave the end of the sluice trough which is opposite the feed end.

This is the field of development to which the present invention pertains; and the invention has utility in the concentration of all materials which may be subjected to the foregoing operations, and particularly mineral ores. Examples of these ores are the ores of gold and silver, gold quartz, copper, copper and silver, tungsten scheelite, thorium, gold placer sands, Zinc and lead, ground scrap mica, zinc carbonate, beryllium, etc.

An object of the present invention is the provision of a concentrator of the reciprocatory sluice trough type in which the trough is comprised of an endless power-driven conveyor.

The invention also comprises the provision of a concentrator of the endless power-driven conveyor sluice trough type in which novel and improved means are provided for dividing the conveyor into a longitudinally disposed series of compartments.

Finally, it is an object of the present invention to provide a concentrator of the reciprocatory sluice trough type which will be relatively easy and inexpensive to manufacture, simple to assemble, disassemble, adjust, clean, maintain, and repair, and rugged and durable in use.

Very broadly, the present invention achieves these objects by providing a concentrator of the reciprocatory sluice trough type, in which the trough is an endless conveyor having a series of compartments which dump one by one as they reach the head of the conveyor. In one conveyor embodiment, the compartments are provided by pivotally interconnected pans or trays which discharge into each other while in another conveyor embodiment the endless member is unitary and constructed of flexible material.

Other features and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a concentrator according to the present invention, showing the trough in its operative position and the material feeding means in feeding position;

FIGURE 2 is a plan view of a concentrator according to the present invention, with the sluice trough removed;

FIGURES 3, 4 and 5 are enlarged fragmentary crosssectional views taken on the lines 3-3, 4-4 and 5--5, respectively, of FIGURE 2;

FIGURE 6 is a cross-sectional view taken on the line 66 of FIGURE 5;

FIGURE 7 is a diagram of the loci of various points on the sluice trough during reciprocatory movement thereof;

FIGURES 8, 9 and 10 are velocity-distance diagrams illustrating various relationships of components of the movements of various points on the sluice trough;

FIGURE 11 is a fragmentary elevational view of a sluice trough comprising an endless power-driven conveyor;

FIGURE 12 is an enlarged fragment of the endless member of FIGURE 11; and

FIGURE 13 is a view somewhat similar to FIGURE 12 but showing in perspective a fragment of another embodiment of endless member for use in the environment of FIGURE 11.

Referring now to the drawings in greater detail, the major aspects of the novel concentrator of the present invention will be described under separate headings, as follows:

Adjustable Frame In FIGURE 1, there is shown a concentrator according to the present invention, indicated generally at 1. Concentrator 1 rests on a first base comprising flooring 3 and comprises a second base or frame 5 in the form of an elongated, generally rectangular open framework. Supported generally horizontally on frame 5 is an elongated sluice trough 7 which is longitudinally and laterally oscillable relative to frame 5.

At its end corresponding to the tail end of sluice trough 7, frame 5 carries a rocker 9 which is supported for rocking movement about a horizontal axis perpendicular to the longitudinal extent of trough ,7 in an upwardly open cradle -11 which rests on flooring 3. At its opposite end, that is, the end corresponding to the head end of trough 7, frame 5 carries in unitary assembly an overhanging shelf 13 on which the trough drive is supported. An extensible and retractable screw jack 15 engages beneath shelf 13 and acts between the portion of frame 5 comprised by shelf 13 and flooring 3. A handwheel '16 enables lengthening and shortening of jack 15 thereby to raise or lower the engaged end of frame 5 and alter the inclination of trough 7 by raising or lowering the head end thereof. It will be appreciated that frame 5 is supported on and between rocker 9 and jack 15, so that upon adjustment of the length of jack 15, frame 5 rocks about rocker 9. In place of a single centrally disposed jack 15, a pair of jacks mounted at the head end on opposite sides of frame 5 and operated in unison by a single handwheel or the like through bevel or other gear drive can be used to advantage, particularly on larger machines.

The drive for trough 7 is mounted onshelf 13 and since trough 7 is supported on frame 5, it will be appreciated that the inclination of trough 7 can thus be altered without in the least affecting the continuity of the drive or requiring any other adjustive steps. It will also be appreciated that different inclinations of trough 7 are desirable in the handling of various materials having particular particle sizes and densities and that in any event trough 7 will be somewhat downwardly inclined from its head end to its tail end to promote movement of material along its length. The optimum inclination for a particular concentration operation will be determined by trial. To this end, a pointer 17 mounted on frame registers with indicia on a fixed scale 18. Once the optimum inclination for a particular feed composition or feed rate has been attained, the scale reading can be noted and the frame quickly set at this reading for subsequent concentration operations of a similar nature. A bubble level 19 is mounted horizontally on and transversely of frame '5 and indicates any undesirable lateral inclination of trough 5.

Trough Drive The trough drive supported on shelf 13 comprises a drive motor 20 which in the illustrated embodiment is electric but could be powered by gasoline or other means. Motor 20 has the usual drive shaft terminating in a drive pulley 21 which is adjustable as to effective driving radius so as to obtain various drive speeds. A drive belt 23 connects pulley 21 with the larger pulley of a gear reduction unit 25 which rotates a rotor 27 about a vertical axis counterclockwise as seen in FIGURE 2. Rotor 27 has a diametral slot 29 across its upper surface in which an eccentric drive pin 3-1 may be clamped at any selected distance from the axis of rotor 27. A pitman 33 is journaled at one end on drive pin 31 and at its other or trough end on a connector pin 35. Pitman 33 is provided intermediate its length with an adjustable telescopic sleeve assembly 36 for changing the length of pitman 33 thereby to alter the movement of the trough in a manner to be described hereinafter.

A pair of longitudinally spaced crosspieces 37 extend between and interconnect a pair of parallel, longitudinally disposed side channel members 39. Connector pin 35 is secured on a vertical axis beneath the crosspiece 37 which is disposed adjacent the head end of trough 7. Channel members 39 are interconnected at their ends to form an open rectangular frame 41 which is the principal support of trough 7. Frame 41 in turn is supported on frame 5 for longitudinal reciprocatory movement relative thereto by four brackets 43, two of which are secured beneath the ends of each crosspiece 37. Each bracket 43 retains within its lower end a spherical roller 45, the rollers 45 being supported for rolling movement on a pair of longitudinally spaced plates 47 which extend transversely of the top of frame 5, all as shown in FIG- URE 3.

Frame 41 thus provides an upwardly open base on the inwardly extending horizontal channels of which trough 7 detachably rests. Reciprocatory motion is imparted to frame 41 and hence to trough 7 by the drive train between and including motor 20 and pitman 33, and the speed and stroke of this drive is variable by adjustment of drive pulley 21 and/ or drive pin 31 as described above. The optimum adjustment of drive pin 31 in slot 29 will be found experimentally for each set of operating conditions. The marginal edges of slot 29 are provided with indicia so that drive pin 31 can be quickly reset at its optimum position for subsequent operations of a similar nature.

Shelf 13 need not be disposed in line with frame 5, as shown in FIGURE 2, but may be placed at variousangles to the longitudinal extent of frame 5 when viewed from above. For example, a highly desirable arrangement of shelf 13 is such that pitman 33 be disposed roughly parallel to the oblique line of movement of the head end of the trough, as will be described hereinafter.

Material Feed The material to be concentrated is fed to the head end of trough 7 adjacent the drive train by a feed hopper 49 supported on a movable carriage 51. Carriage 51 is comprised of open framework which straddles the drive train in feeding position and is movable away from the concentrator when the material feed is discontinued. For this purpose, carriage 51 is supported on four wheels 53 which roll on a pair of tracks 55 which are parallel 4 to each other and to the longitudinal extent of frame 5 so that the carriage may be rolled into and out of feeding position.

A vibratory feed trough 57 is mounted on carriage 51 below the lower end of hopper 49 to receive material from the hopper and feed it at a controlled rate to the head end of trough 7. Trough 57 is given rapid vibratory feeding movement by an electromagnetic vibratory motor 59 mounted on carriage 51 and controlled as to frequency of vibratory movement from a control box 61 which is mounted on carriage 51 and which also includes a switch for actuating motor 5-9.

The material is fed to trough 7 dry and the water to make up the slurry is separately fed to the head end of trough 7 via a water supply conduit 62. Conduit 62 is secured adjacent its discharge end to carriage 5'1 and has a flexible intermediate portion to enable movement of carriage 51 without disconnecting the water supp-1y.

Separate from conduit 62 is a spray pipe 63 having a portion that extends lengthwise above frame 5. A multiplicity of downwardly opening holes 64 extend through the underside of the horizontal portion of pipe 63 along most of the length of trough 7. Holes 64 are directed toward trough 7; and when water under pressure is supp-lied to pipe 63, a multiplicity of sprays of water will be directed into trough 7 from above. The purpose and effect of these multiple jets of water is to maintain the slurry in the trough in a state of agitation additional to that imparted to the slurry by trough movement, thereby to prevent packing of the material in the trough and to aid in the uniform movement of the material through the trough.

Trough Movement The drive train described above assures that the movement of trough 7 will be generally longitudinally reciprocatory. The particular paths of movement followed by various points on the trough, however, are determined by a pair of guideways, one disposed adjacent the head end of trough 7 and the other disposed adjacent the tail end of the trough. First guideway 65 is the guideway adjacent the head end of the trough and is comprised of a horizontal plate 67 extending transversely of frame 5. Secured to the upper surface of plate 67 is a pair of parallel channels 69 having upstanding spaced parallel flanges. Channels 69 are disposed at a substantial and adjustable angle to the longitudinal extent of trough 7 in all trough positions, for example, at an angle of 45 to the mean trough position indicated in FIGURE 2. A crosspiece 71 interconnects the undersides of longitudinal channel members 39 of frame 41, and a guide roller 73 is journaled for rotation about a vertical axis beneath crosspiece 71. Thus, upon reciprocatory movement of frame 41 and with it trough 7, roller 73 moves along a diagonal path between channels 69, as best seen by comparison of FIGURES 2 and 4, thereby to impart a substantial lateral component to the reciprocatory movement of trough 7.

Means are also provided for varying the lateral and longitudinal components of the movement of trough 7 adjacent roller 73 by rotation of plate 67 about a vertical axis which is preferably but not necessarily the axis of roller 73 in the mean position of trough 7 thereby to alter the inclination of channels 69' about that axis. For this purpose, plate 67 is provided with a downwardly depending pin 74 journaled for rotation in a crosspiece of frame 5 and is provided adjacent its ends with a pair of concentric arcuate slots 75 in each of which is disposed one of a pair of posts 77 mounted on opposite sides of frame 5. Posts 77 include clamping nuts for clamping the plate 67 in any adjusted rotated position; and when these clamping nuts are released, plate 67 may be rotated in its horizontal plane with posts 77 moving in slots 75. Means are provided for thus moving plate 67, comprising a longitudinally extending adjustment rod 79 which is externally screw-threaded and connected at one end to an end of plate 67. The screw-threaded portion of rod 79 is disposed in an internally screw-threaded bracket 81 secured to frame 5 and the other end of rod 79 carries a crank handle 83. Upon rotation of handle 83, rod 79 turns and moves lengthwise in bracket 81 thereby to rotate plate 67 about a vertical axis which preferably but not necessarily passes through first guideway 65.

The optimum adjustment of plate 67 about its vertical axis will be determined by trial for each set of operating conditions. The marginal edges of at least one arcuate slot 75 are provided with indicia with which posts 77 register so that a position of plate 67 found desirable for a particular set of conditions can be quickly duplicated.

Second guideway 85 is disposed adjacent the tail of trough 7 and restrains a point on that trough to rectili near movement longitudinally of the mean longitudinal extent thereof. As best seen by comparison of FIG- URES 2, 5 and 6, guideway 85 comprises an elongated guide plate 87 disposed longitudinally of and supported on frame 5 and having a cover plate 89. Plates 87 and 89 define between them a longitudinally extending T- groove in which is disposed for longitudinal sliding movement the head of a T-member 93 having an upstanding web at the top of which is secured a forwardly extending bracket 95. A ball 97 depends from the forward end of the bracket 95 and is disposed for universal movement in a socket 99 carried at the rear end of a longitudinally extending bracket 101 which is secured at its forward end to the underside of the rear crosspiece 37. In this way, that portion of trough 7 which intersects the vertical axis of ball 97 at all time follows a path parallel to and above T-groove 91.

In general, therefore, it will be appreciated that trough 7 has a lengthwise reciprocatory movement characterized by longitudinal and lateral components and that portions of trough 7 adjacent the head end thereof tend to have a substantially greater component of lateral movement than the portions of the trough adjacent the tail end thereof and that portions of the trough adjacent the tail end thereof tend to have a greater component of longitudinal movement than portions adjacent the head end. It will also be realized that the variation in the magnitude of these lateral and longitudinal components will be progressive from one end of the trough to the other. For a better understanding of the various movements of different portions of the trough and their significance, the paths of movement of various parts of the trough are shown dia-, grammatically in FIGURE 7 and the correlation of these relationships with the factor of trough velocity is indicated in FIGURES 8, 9 and 10.

In FIGURE 7, the line 103 represents the mean longitudinal center line of the trough and is parallel to T-groove 91. Line 10 5 represents the locus of the axis of guide roller 73 in channels 69. Line 107 represents the locus of a point on trough 7 intermediate roller 73 and ball 97; while line 109 represents the locus of a point about an equal distance along trough 7 on the opposite side of line 105 or roller 73. Hence, when trough 7 is in its mean position parallel to T-groove 91, these four points along the trough will correspond to the four zero positions along line 103. It will also be noted that on either side of each zero position along each locus is a plurality of sequential numerals of opposite sign on each side of the Zero point. Along the right end of line 103 as seen in FIGURE 7, these numerals are evenly spaced apart, which represents movement of ball 97 through equal increments of distance.

It is of particular importance to observe in connection with FIGURE 7 that it is only along line 103 that these increments remain of constant length. Along lines 105, 107 and 109, the increments progressively increase in length while moving from plus values toward minus values. Thus, in the most noticeable case, that of locus line 109, it will be seen that the increment between points 6 and 7 is only about half that between points -2- and 3. This means that while a point adjacent the tail of the trough is traversing a certain distance during one portion of the stroke, a portion adjacent the head of the trough may be traversing a distance not much greater; but during another portion of the stroke, a part of the trough adjacent the tail may traverse the same distance but the portion adjacent the head will traverse a distance more than twice that distance. In other words, during the extension stroke, the head of the trough is accelerating relative to the tail of the trough and during the retraction stroke the head of the trough is decelerating relative to the tail of the trough.

The relationship may be better understood by reference to FIGURE 8. Considering that ball 97 in a hypothetical case is caused to move rearwardly at constant velocity, this relationship would be seen in FIGURE 7 as the movement of a point along line 103 from point 7 toward the minus end at the extreme right of FIGURE 7. A point on the opposite end of trough 7 would move along line 109. The movement of the point along line 103 could then be considered to be represented by movement from left to right with constant velocity along the abscissa D of FIG- URE 8, and in terms of FIGURE 8 the velocity of the point moving along line 109 would then be represented against the ordinate V by the rising curve of FIGURE 8.

However, in reality, ball 97 never moves at constant velocity since it is in something approaching simple harmonic motion, as represented roughly by the curve of FIGURE 9. Therefore, the motion curve along 109 can be approximated by combining the curves of FIGURES 8 and 9, with the result that the curve of FIGURE 10 is obtained. The significance of FIGURE 10 is that it demonstrates that the acceleration and deceleration of the head end of the trough, as represented by the slope of the curve of FIGURE 10, is much greater in extended positions of the trough than in retracted positions of the trough.

From the standpoint of concentrating materials by use of a reciprocating sluice trough, it will be understood that the velocity of any point on the trough is immaterial but that the acceleration or deceleration of that point is all-important. Hence, it will be apparent from FIGURES 9 and 10 that these acceleration-deceleration relationships vary progressively along the length of the trough of the present invention. Stated in another way, the maxima of the velocity-distance curves of points along the trough move progressively to the left from the head of the trough to the tail of the trough, as seen by comparison of FIG- URES 9 and 10. It will also be understood that further toward the tail of the trough beyond ball 97, the maximum of the curve is always to the left of the mid-point of the absissa, so that the acceleration and deceleration are greater adjacent retracted trough positions than adjacent extended trough positions.

From the standpoint of a concentration operation, the significance of all of this is that adjacent the head of the trough the material tends to be thrown more vigorously over the riffles than adjacent the tail of the trough, so that a gross separation of the heaviest particles of concentrate is rapidly and effectively achieved adjacent the head of the trough, while adjacent the tail of the trough a finer, more gentle and more thorough separation of the fines is achieved. Hence, the double guideway arrangement of the present invention provides a highly desirable means for regulating the velocity of any portion of the trough at any point along its path of movement so as to obtain optimum concentrating effect.

A second advantage resulting from the double guideway arrangement is that the direction of movement of points along the trough varies from head to tail thereof. As seen by a comparison of the inclinations of lines 103, 105, 107 and 109, the lateral component of trough movement decreases from head to tail thereof. In a concentrating operation, this means that the material at the head of the trough is thrown with greater force against the side walls of the trough than at the tail of the trough.

This contact with the sides of the trough is in addition to that with the ritfles, so that the agitation of the material adjacent the head of the trough is much greater than adjacent the tail of the trough. This increased agitation is desirable near the head of the trough to etfect the initial crude separation but would be undesirable adjacent the tail of the trough where it is desired to recover the fines; and hence the double guide arrangement of the present invention insures optimum concentrating characteristics with regard to the turbulence of the material in the trough.

A third and more subtle advantage of the double guide arrangement of the present invention will be appreciated from a consideration of FIGURE 7, in which it will be seen that lines 107 and 109 are not straight but are concave and open toward each other. This means that the portion of the trough on one side of first guideway 65 is imparting a swirling movement to the material while that portion of the trough on the other side of the first guideway is imparting a reversed swirling movement to the material. From the standpoint of a concentration operation, this swirling movement is advantageous in much the same manner as in panning for minerals by hand; and in addition, it will be appreciated that the reversal of the tendencies to impart swirling movement on opposite sides of the first guideway tends in turn to balance the dynamic forces of the material in contact with the trough.

For ease of understanding, FIGURE 7 shows the area swept by the longitudinal center line of trough 7 to be disposed about half on one side of line 103 and half on the other side of line 103. In actual practice, however, this relationship will rarely obtain. For example, it has been found that optimum concentration of most metallic ores is achieved when pitman 33 is lengthened by adjustment of sleeve assembly 36 so that this area is disposed .at least primarily below line 103. For certain non metallics, it has been found best to shorten pitman 33 by adjustment of assembly 36 so that this area lies at least primarily above line 103. Thus, the mean longitudinal outer line of trough 7 will rarely if ever include the midpoints of the loci of all points along the longitudinal center line of trough 7. Of course, as before, the optimum adjustment of the length of pitman 33 will be determined by trial for each particular type of concentration operation.

The shape and direction of the locus of any point on the trough can be varied as desired by rotation of plate 67 and/or by adjustment of drive pin 31, drive pulley 21 and telescopic assembly 36.

Endless Conveyor As seen in FIGURE 11, trough 7 may be replaced by an alternative form of sluice trough comprising an end less power-driven conveyor indicated generally at 241 and comprising an open framework 243 which rests at its lower end on an open rectangular horizontal frame 245 of about the same size and shape as trough 7 and which is adapted to rest on open frame 41 in the same manner as and instead of trough 7. Framework 243 supports conveyor guideways about which is trained an endless conveyor member 247 comprised of a plurality of pivotally interconnected open-topped pans or trays 249. The head end of conveyor member 247, which is the end at the left of FIGURE ll, is trained about the head wheel assembly 251 which is driven to circulate conveyor member 247 by a speed change device or variable speed mechanism 253 which in turn is driven by electric gear unit motor 255. In this way, any of a plurality of linear velocities may be imparted to conveyor member 247, as desired.

Conveyor 241 thus provides a sluice trough having a plurality of longitudinally spaced outstanding rifiles extending from side-to-side thereof and enjoys the same lengthwise reciprocatory movement with lateral components as does trough 7 of the preceding embodiment. Thus, it is intended that in connection with the embodiment of FIGURE 11, the carriage 51 also be used so as to feed material from hopper 49' or other feed device such as an endless belt or vibratory feeder. Contrary to the practice in connection with the preceding embodiment, the feed point is about midway between the end-s of the conveyor member. As before, water to make up the slurry is fed to the head end of the upper run of the conveyor member by a water supply conduit 62; and a longitudinally extending spray pipe 63' directs agitating jets of water onto the material in the conveyor trough through a multiplicity of holes 64'. However, conveyor 241 does not empty by inverting to dump. Instead, the progression of the upper run of the conveyor to the left as seen in FIG- URE 11 and counterclockwise about head wheel assembly 251 assures that the compartments between the riflles of the conveyor will successively dump by gravity to an opentopped receptacle 257, so that the production of a uniform concentrate of any desired characteristics is continuous rather than intermittent. To clean the receptacles as they successively dump, receptacle 257 carries thereon a bracket 259 in which is mounted a Water supply conduit 261 which feeds water under pressure to at least one spray nozzle 263 directed toward the conveyor. It should be noted that the spray strikes the conveyor at that portion of the conveyor which is just entering the lower or return run thereof. The concentrates and spray water falling from the head end of the conveyor are caught in receptacle 257 where the concentrates remain for the most part in a state of more or less turbulence induced by the fall of the spray water and concentrates, the excess water in receptacle 257 being discharged by decanting so as to leave at least the heaviest portions of the concentrates in that receptacle.

In order to assure that the Water removed by decanting has been freed of fines, receptacle 257 is provided with a vertical baffle 265 over which excess water passes to an overflow conduit 267 which feeds to a sluice trough 269 having a plurality of longitudinally spaced laterally extending riflles upstanding from the bottom thereof. In this latter sluice trough, the last of the fines are separated from the water. Trough 269 is adjustably inclined downwardly from its head end to its tail end to promote movement of material in this direction. Meanwhile, at the tail end of conveyor 241, the water and railings from the initial separation are continuously falling into a t-ailings discharge trough 273 and being carried away to the right of FIGURE 11.

Although conveyor 241 has the same reciprocatory movement as. trough 7, since it rests on the same frame 41, it is important to note that receptacle 257 and sluice trough 269 are fixed relative to conveyor 241 and may for example be mounted on frame 5. The significance of this feature is that the agitation induced by movement of conveyor 241 aids in an initial rough separation of concentrates from gangue, while the fixed mounting of receptacle 257 and trough 269 assures that the maximum quantity of fines Will be recovered. Also, the positioning of trough 269 directly beneath conveyor member 247 assures that the last quantity of Wash water and any concentrates therein will proceed to the secondary separation operation being conducted in trough 269 and will be recovered regardless of whether all the wash water is caught in receptacle 257. In any event, sluice trough 269 is readily removable from the assembly for emptying and cleaning.

The structure of endless member 247 is also of importance and two highly desirable embodiments of this structure are separately illustrated in enlarged fragmentary views in FIGURES 12 and 13. In FIGURE 12, the trays 249 are seen to have an imperforate bottom 275 which is integral with opposite upstanding side walls 277 which terminate upwardly in inturned flanges 279. Bottom 275 terminates forwardly in a leading end wall 281 of substantially less height than side walls 277, which has at its upper edge a downwardly rearwardly inclined lip 283 connected with end wall 281 by an integral curved portion. At its rear end, bottom 275 is integral with a trailing end wall 285 which is also of substantially less height than side wall 277 but is of a height greater than the height of leading end wall 281 by an amount equal to about the thickness of the sheet metal material of trays 249. Trailing end wall 285 has a horizontal rearwardly extending portion 287 which terminates rearwardly in a downwardly rearwardly inclined lip 289 adapted to overlie and contact over a substantial area the underlying lip 283- of the next tray 249 to the rear. Integral with horizontal portion 287 and inclined lip 289' at each side thereof are upstanding flanges 291 which terminate upwardly a substantial distance below inturned flanges 279 and are faired inwardly toward each other by an amount about equal to the thickness of the sheet metal material of trays 249, so that the forward ends of side walls 277 overlie a major portion of upstanding flanges 291 in closely contiguous relationship. Trays 249 are formed of sheet metal cut and bent up to shape, and the lower corners thus. provided, which are shown open in FIGURE 12, are filled with solder to provide a water-tight construction.

Secured to the underside of the leading end of bottom 275 is a forwardly extending hinge bracket 293 which interfingers with a corresponding rearwardly extending hinge bracket 295 secured to the underside of the rear end of bottom 275 of the next adjacent tray 249. A hinge pin 297 passes through the eyes of brackets 293 and 295 to provide a pivotal interconnection between adjacent trays 249. Thus, in assembled relationship, the trays 249 along the upper or concentrating runs of conveyor 241 will have the relationship illustrated in FIG- URE 12, with the bottoms 275 thereof coplanar and the remainder of the trays otherwise aligned. The upper portions of side walls 277 and flanges 279 of adjacent trays will abut endwise, and the structure 281, 283, 285, 287 and 289 will provide riflles having downwardly rearwardly inclined trailing projections. At the same time, free movement over the head end of the conveyor frame to discharge and up over the tail end of the frame to return to the concentrating run is facilitated. Moreover, the contact of lips 283 and 239 over substantial areas and the contiguity of upstanding flanges 291 and side walls 277 over substantial areas assures that the sluice trough provided by the straight upper run of conveyor member 247 will not leak.

In FIGURE 13 there is shown another embodiment of an endless sluice trough, in which an endless conveyor member 299 is molded integrally of neoprene, natural rubber or the like and may if desired be provided with cord reinforcing (not shown). In any event, all portions of conveyor member 299 are elastic deformable and waterproof. This embodiment comprises an end less sleeve or band having a substantially flat bottom 301 from opposite sides of which upstand side walls 303 run- :ning full length about the conveyor member. Upstanding from bottom 301 and extending transversely from side wall to side wall is a plurality of longitudinally spaced riffles 305 which are integral both with bottom 301 and with side walls 303. Between each pair of adjacent rifl'les 305 is a plurality of longitudinally spaced slots 307 which extend through each of side walls 303 and are of a depth more than half the height of side walls 303 and open through the outer or upper edges of side walls 303. A plurality of bellows 309, one individual to each slot 307, is disposed on the inner or confronting sides of slots 307, and each of them is secured to its side wall 303 about the margins of the corresponding slot 307. It should be noted that there is considerable slack in each of the bellows 309 when bottom 301 is straight as seen in FIGURE 13, so that each slot 307' may be spread a considerable distance before the bellows 39 are straightened. Bellows 309 may be of the same material as conveyor member 299 and may for example be vulcanized or riveted thereto. In either event, slots 307 may be as deep as possible consistent with the riveting or vulcanizing operation.

In use, the conveyor member 299 of FIGURE 13 can simply replace that of the FIGURE 12; and if desired, head wheel assembly 251 may include the usual smooth cylindrical drum for endless belt conveyors (not shown). In the straight upper or concentrating run, the side walls 303 and bellows 309 coact with imperforate water-tight bottom 301 to provide a water-tight sluice trough having riflles 305 therealong; and the oscillatory movement discussed in connection with sluice trough 7 provides the concentrating movement. As the endless member 299 moves over the head wheel assembly, it dumps and is cleaned essentially as in the preceding endless conveyor embodiment. The slots 307 in side walls 303 enable these side walls to remain perpendicular to bottom 301 even while passing about the head and tail of the conveyor frame and bellows 309' keep the slots closed even in their stretched positions, so that the spray water from nozzle 263 .at no time washes material off the sides of the conveyor to the extent that it misses receptacle 257.

From a consideration of all of the foregoing disclosure, it will be obvious that each of the initially recited objects of the present invention has been achieved.

Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

What is claimed is:

l. A concentrator comprising an endless power-driven conveyor having an elongated upper run and a lower run, means for circulating the conveyor, means for bodily reciprocating the conveyor, the conveyor having upstanding side edges and a plurality of upstanding riflies extending transversely between and spaced apart longitudinally of the side edges to define along the upper conveyor run an elongated sluice trough, an open-topped receptacle disposed beneath the end of the conveyor toward which the upper conveyor run moves, an elongated stationary sluice box having a plurality of upstanding rifiles disposed transversely and spaced apart longitudinally thereof .and having a material receiving end, and overflow means on the receptacle and communicating with the receiving end of the sluice box to deliver to the sluice box material discharged from the conveyor and overflowing the receptacle, the open-topped receptacle being separate from the sluice box and the overflow means overlying the receiving end of the sluice box.

2. A concentrator comprising an endless conveyor member comprised of a series of trays, each tray having a bottom wall and a pair of upstanding side walls and a pair of upstanding end walls of a height less than the height of the side walls, means disposed at each end of each tray adjacent the junctions of the end and bottom walls and pivotally interconnecting each tray with each adjacent tray at each end of each tray for swinging movement of the trays relative to each other about axes disposed substantial distances below the tops of the end walls of the trays, one said axis being disposed endwise outward beyond each end wall of each tray, and an overflow conduit having a bottom wall and upstanding side walls and extending from the top of one end wall of each tray and overlying the adjacent end wall of the adjacent tray.

3. A concentrator as claimed in claim 2, the side walls of the overflow conduit being integral endwise continuations of the side walls of the tray but being spaced apart a distance less than the distance between the side Walls of the tray.

4. A concentrator as claimed in claim 2, the bottom wall of the overflow conduit terminating endwise in a downwardly inclined end portion extending beyond said adjacent end wall and said adjacent end Wall having a lip downwardly inclined from the top thereof and underlying and contiguous to said downwardly inclined end portion when the trays are longitudinally aligned.

References Cited in the file of this patent UNITED STATES PATENTS 92,594 Eltonhead July 13, 1869 12 Stephens Nov. 3, Conkling Mar. 25, Dale June 14, Stewart June 3, Reno June 28, Craft Mar. 1, Rodman Mar. 29,

FOREIGN PATENTS France June 9,

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