US2271650A - Jig - Google Patents

Description

Feb. 3, 1942.

M. KRAUT 2,271,650

I JIG Filed Sept. 6, 1938 2 Sheets-Sheet; 1

INVENTOR. Max Kroc/7;

ATTORNEY.

M. KRAUT Feb. 3, 1942.

JIG-

2 Sheets-Sheet 2 Filed Sept. 6, 1938 IN VENTOR. Max Maui,

ATTORNEY.

Patented Feb. 3, 1942 JIG Max Kraut, San Francisco, Calif.

Application September 6, 1938, SerialNo. 228,518

4 Claims.

This invention relates to apparatus used for the purpose of recovering free minerals or metallic particles from ores or gravel mixtures. The apparatus of my invention is of that class known in the industry as a jig, and may be employed in the recovery of such materials as native gold, tin oxide (cassiterite), tungsten in the form of scheelite or wolframite, heavy sulphides of the base metals such as galena and pyrite, and other such materials.

Briefly, a jig is an apparatus comprising a permeable bed, preferably composed of sand and other particles, supported by a screen, over which flows a mixture of water, gangue and themineral desired to be recovered, there being means to provide an intermittent upward flow of water through the bed resulting in a classifying action therein by which the relatively heavy mineral desired to be recovered passes through the bed into a hutch below while the gangue passes over the bed and out of the apparatus.

It is an object of my invention to provide an apparatus by use of which unusually high metallurgical recoveries are obtained.

Another object of the invention is to provide a jig in which water is positively moved alternately in the upward and downward directions through the bed and in which the action of the water on the bed is substantially uniform over its entire area- I a Another object is to provide means for imparting a rapid; reciprocating. motion to the bottom of the jig, which motion is of such nature that the downward stroke is much faster than the upward stroke, resulting in more eflicient separation of the particles desired to be recovered,

Another object of the invention is to provide a reciprocating means driven by water power- Another object of my invention is to provide an apparatus which requires very little vertical space below the tailings discharge, and is free from all encumbrances due to moving mechanisms at the bottom of the jib below the hutch.

Another object is to provide a jig in which the mechanism for reciprocating the bottom is located at the top of the jig Where it is readily accessible and does not interfere with the drawing oft of concentrate from the bottom of the jig.

A further object is to provide an apparatus in which is assured a continuous discharge of concentrate from the bottom of the jig through a small discharge opening without the requirement of high head room underneath the jig.

Still another object of my invention is to provide an apparatus which-is cheap to construct, requires a minimum of attention, and is of long life. 1

These and other apparent objects I attain in a manner which will be clear from consideration of the following description taken in connection with the acoompanyingdrawings, of which:

Fig. 1 is an elevational view of my apparatus, shown partly in section.

Fig. 2 is a sectional view of my apparatus taken along the line 22 in Fig. 1.

Fig. 3 is an enlarged view, partly in section; of the means for causing reciprocation of the bottom of the jig, the controlling valve member being shown in the position in which it is undeflected'.

Fig. 4 is a sectional View through the apparatus shown in Fig. 3 taken along the line 4-4. Fig. 5 is a diagrammatic view showing the controlling valve in its uppermost position.

Fig. 6 is a diagrammatic view showing the controlling valve in its lowermost Position,

' Fig. 7 illustrates an alternative construction of is supported between a lower grid l4 resting on the frame l0 and an upper grid [5 forced downward against the screen [3 by screws l6 acting upon blocks I! in contact with the upper surface of grid l5 at the sides of the jig. Adjacent the discharge trough I2 is another screen I8 supported, at a somewhat lower elevation than screen l3, between a lower grid 20 resting on frame l0 and an upper grid 2| which is forced downward against the screen ill by screws 22 acting upon blocks 23 in contact with the upper surface of, the grid 2| at the sides of the jig. The grids I4, I5, and 20, 2| preferably divide the horizontal area of. the screens into a multiplicity of rectangularly shaped compartments, as seen best in Fig. 2. In the compartments formed by the grids above the screens is preferably placed a layer 24 of lead or steel shot about one inch thick and on top of this is built up a layer 25 of sand. The shot and sand layers 24 and 25 com prise a permeable bed of particles which is spoken of as the bed of the jig.

It is desirable to move water alternately upward and downward through the bed and to this end I provide below the grids l4 and 20 a vertically movable pan 26, preferably made of relatively thin resilient material such as thin sheet iron, and sloping gently from the periphery to the center where an outlet pipe 21 is connected and provides an outlet of relatively small capacity from the space above the pan, The pan 26, which is preferably of substantially the same size and shape as the bed of the jig, is attached at its periphery to a section of bellows 28 of flexible material such as rubber or canvas, the

upper end of which is secured to the frame In. The flexible material 28 thus constitutes an expansible connection between pan 26 and the screens above whereby is formed an enclosed space of variable volume between the pan and the bed. A spider 38 comprising a plurality of downwardly and outwardly extending arms is attached to the pan 26 and to a vertically extending rod 3| alternately moved upwardly and downwardly by the actuating means 32 located on the top of the jig.

The actuating means 32 is adapted to be operated by water pressure and to produce reciprocating motion of the rod 3|. An outer cylindrical housing 33 is secured to a bridge-like structure 34 spanning the jig from side to side and attached to the frame I0. Within the housing 33 is located a cylinder 35 attached to the housing 33 at circumferentially spaced locations and opening at top and bottom into the housing 33. A water supply pipe 36 is screwed into the housing 33 and cylinder 35 and feeds water under pressure directly into the cylinder 35. The cylinder 35 at its lower end is conical in shape and serves as a valve seat 39 for a circular valve disc 31 of resilient material such as rubber which is preferably of tapering cross-section, facilitating flexing of the disc. A piston 38 closely fitting the cylinder 35 is adapted to move therein above the water inlet pipe 36. The piston 38 and valve disc 31 are mounted on an axial tube 40, being pressed against the shoulder 4| by the tightening of nut 42. The valve disc 31 is of area less than that of the piston 38 and is mounted so as to be unsupported in its peripheral portion. The tube 40 extends upwardly through a bearing 43 mounted in a cover 44 secured to the top of housing 33 by bolts 45. A lubricating fitting 50 is connected through the cover 44 to conduct lubricant to the bearing 43. A diaphragm 49, preferably of rubber or canvas, and apertured to permit tube 40 to pass therethrough, is clamped between housing 33 and cover 44 to protect the bearing 43 from splash of water. The rod 3| passes through the tube 40, has a shoulder abutting the lower end of tube 40, and carries a nut in threaded engagement therewith at its upper end which securely clamps the tube 40 and associated parts on the rod 3| for movement therewith. A spring 46 surrounds the tube 40, bears at one end on the cover 44 and at the other end against a washer 41 retained in an adjustable position by nut 48 in threaded engagement with tube 40. The spring 46 acts to balance part, of the load due. to the weight of pan 26, water above the pan, rod 3| and associated parts, whereby the pressureoand. amount of water required to operate the reciprocating means 32 is reduced. It should be noted that the spring 48 should never be made so strong as to completely balance all the load on rod 3| for then there would be nothing to return the valve to the closed position.

Attached to the housing 33 at its lower end and in communication with the space within the housing 33 and cylinder is a fitting 52 having a side outlet pipe 53 connected thereto and a pipe 54 connected to the bottom surrounding rod 3|, there being space left between the rod 3| and pipe 54. The pipe 54 passes downwardly through the bed of the jig and opens into the hutch, which is the space below the grids l4 and 20 and above the pan 26. The grids l4, I5, 20, and 2| and screens l3 and I8 ar shaped, as seen best in Fig. 2, to permit the tube 54 to pass through the bed. In the bottom of fitting 52 is preferably located a washer 55, preferably of rubber, clamped between a shoulder of the fitting and a nut 56 in threaded engagement with the fitting. The washer may pack the rod 3| in contact therewith to prevent passage of any fluid into the pipe 54 or it may be of any suitable internal diameter topermit passage of any desired proportion of the available fluid past the washer, through the pipe 54 and into the hutch. A water supply pipe 51, provided with a valve 58, is preferably connected to pipe 54 below the fitting 52 to supplement the supply of water to the hutch,

if desired, or to alone supply the make-up water required if none is permitted to pass from the fitting 52 into the pipe 54.

In the operation of the actuating means 32 to reciprocate the rod 3|, water under pressure enters cylinder 35 through pipe 38 and acts upon both piston 38 and disc 31, the force on piston 38 in an upward direction being greater than the downwardly directed force on disc 31 by reason of the greater area of piston 38. The piston 38 therefore moves upwardly. If the disc 31 were inflexible it would also move upwardly coincidentally with piston 38; but being flexible, the periphery of disc 31 is held down in contact with the conical seat 39 while the center of the disc connected to piston 38 rises with the piston, as shown in Fig. 5. The piston 38 continues to rise until a critical point is reached where the periphery of the disc 31 can no longer be held in contact with the seat 39 by the water -pressure, and the disc 31 then breaks from the seat. The valve disc snaps open quickly as the pressure on opposite sides of it quickly equalizes. At the same time the piston 38 moves farther up in the cylinder due to the momentum it has acquired. Thus the opening closed by disc 31 is rapidly opened, resulting in an instantaneous drop in pressure which, among other things, depends upon the restriction of the valve 60 in supply pipe 36. The sudden drop in pressure Within the cylinder 35 together with the reduced pressure underneath disc 31 due to the high velocity of water passing through the narrow opening between the seat 39 and the disc 31 and associated parts causes the piston 38 to be pulled rapidly downward by the weight of rod 3|, pan 28, and the water and concentrate in the hutch. As soon as the piston and valve structure has fallen to a point where disc 31 contacts seat 39 pressure starts to build up in cylinder 35. Since, however, the disc 31 is flexible, it can be distorted into the shape shown in Fig. 6 in which condition the volume within the cylinder between piston 38 and valve disc 31 is greater than in the condition illustrated in Fig. 3. It will .be obvious that pressure cannot build up to a normal value within the cylinder 50 long as this alternately :rising and descending currents 'of volume is increasing. For :this reason the piston 68 and valve disc '31 rsi'nk'to a lowermost position illustrated in Fig. 6. cylinder then builds up quickly and causes the piston 38 to be raised while the periphery ofthe disc'31 is held in contact With'seat 39, the piston and disc going through the position shown in Fig. '3 andon through the remainder of the cycle as previously described. Since any momentum possessed by the moving parts-at the time of unseating of the valve disk 31 is quickly overcome by the unbalanced forceof gravity, there is very little upward movement after this time, and nearly all of the upward stroke of the member 3| takes place while the valve disc 31 is seated on the seat 39.

The water discharged from the cylinder past the disc 31 when in the open position passes into the fitting 52 and out throughpipe 53, a portion thereof, depending upon the opening between washer 55 androd 3i, passing down the pipe 54 to supply make-up water to the hutch. Any water leaking past the piston 38 enters the space between housing 33 and cylinder 35 and runs down to join the discharge water in fitting. 52.

The diaphragm shield 49 prevents any of this water from splashing up into the bearing 43. The resulting reciprocation of rod BI is very rapid and regular. The number of strokes per minute may be adjusted by varying the diameter of the disc 31 or by varying the restriction of the water supply. In one embodiment of the device about 200 complete cycles per minute were obtainable with a disc inches in diameter, and with a disc 4 inches in diameter the number of cycles could be adjusted from 400 to 1000 per minute, finally reaching a vibratory movement. The extent of the movement depends upon the diameter of the disc 31., greater movement being obtained, within limits, by use of a disc of larger diameter. In the device above referred to, a movement of 1 /2 inches was obtained by use of a disc 5 inches in diameter, while a movement of inch was obtained by use of a disc of 4 inches diameter.

The movement of the piston 38 is relatively slow on its upward stroke because a relatively great weight is being lifted by the Water pressure acting only on the difierential area of piston 38 and disc 31, while on the downward stroke the weight connected with rod 3| pulls the piston down very rapidly against a greatly reduced pres sure. This type of reciprocation involving a rapid downward stroke and a relatively slow upward stroke has been found to be particularly adapted to operation of a jig, resulting in more efiicient recovery than with reciprocation of equal velocity on the two oppositely directed strokes. It is understood that the reciprocating means 32 may be advantageously employed in jigs of different construction from the one herein disclosed and may be used for purposes other than reciprocation of a jig.

In the operation of the jig as a whole, the feed, which may comprise gravel or sands in placer operations, or ball mill discharge in milling operations, which have been sluiced with water, is led over the inlet trough I l, onto the bed of sand and shot above the screens I3 and I8, and out over the discharge trough I2. The water fed with the material onto the bed of the jig passes through the screen, and this, together with part or all of the water which motivates the reciprocating means, fills all the space between the bed and the pan 26. The reciprocation of the pan 25 causes The pressure within the water through the i'bedof the iig above the screen. These currents activating the bed have a classifyjng ti n .the material passing through the jig, only the particles of relatively great specific gravity being-able :to sink through the bed against the rising current. As -a result of "this action 'the relatively heavy particles gradually work down through the bed, throughthe screen, and settle on the pan '26, while the lighter gangue particles pass over the bed and out over the discharge trough 12. The type of reciprocation produced by the means 32 in which the water below the bed is moved rapidly on the downward stroke and more slowlyon the upward stroke has been found to result in more eilicient recovery than reciprocation in which the velocity is the same on the two Strokes. Another feature of improved operation is that the velocity of water through the bed is substantially'uniform over the entire-surface of the bed due to the fact that the pan 26, Whose motion is responsible for the movement of water through the bed, is of substantially the same size :and shape as the'bed itself. There is a direct vertical movement of water under all parts of the bed which prevents the existence of boiling action in some areas while other areas are dead, a condition present in some jigs whichseriously-interferes with the metallurgical efficiency of the jig.

The concentrate which falls on the pan 26- moves :down the slopingpan and out through the outlet 2 together with a continuous small stream of water. 'Itwillbeobvious that some "make-up water must be supplied to the space below the screens. If desired the size of washer 55 may be made such as to permit water to -pass down the pipe ".54 in sufiicient quantity to satisfy this demand; or if desired the washer 55 may "pack therod 3| to prevent any water from passing and thetmake-up water'may be supplied through pipe 5'! by adjustment of valve 58.

.One of the features of my apparatus is that very little vertical space is required from the discharge trough down to the floor. This valuable feature is in part achieved by employing the very shallow pan 26, which slopes only very gently toward the center. With such a gentle slope it would ordinarily be difficult for the concentrate to move down to the outlet 21. But since the pan 26 is made of thin flexible material it is distorted upwardly and downwardly from its normal shape as it is reciprocated. Thus the pan 26is continually shaken and the particles of concentrate which settle on it are gradually moved toward the outlet 21.

. The pan 26 may be made of any flexible material which distorts while undergoing reciprocation, thin metal being preferable; but it may, for example, be made of rubber in which case the spider arms 30 may be attached to a metal frame inside the pan and another outside the pan between the members of which the flexible material is clamped.

An alternative construction by which the con centrate may be moved down the pan to the outlet is shown in Fig. 7. In this form a bumper, preferably in the form of a rubber ring whose upper surface conforms to the pan 25, is mounted under the pan 26 surrounding the outlet 21 on a support 66 attached to the frame ID. This bumper 65 is adapted to be bumped by the pan 26 on its downward stroke with the result that the concentrate inside the pan is jarred down the inclined surface toward the outlet 21. It-is evident that the bumper 65 may be employed in connection with a thin flexible pan'as previously described or with a thicker and less flexible pan which would not of itself cause the concentrate to move.

It will be understood that various changes and modifications in design and construction from the apparatus disclosed herein may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

I claim as my invention:

1. A jig comprising in combination: a stationary screen; a permeable bed of particles supported by said screen; a pan positioned below said screen and having an outlet opening therein, said pan being inclined downwardly at an angle toward said opening; an expansible connection between said pan and said screen, whereby is formed an enclosed space of variable volume between said pan and said screen; means including a fluid motor for reciprocating said pan in a vertical direction; and a bumper adapted to be bumped by said pan at the end of one of its strokes, whereby concentrate settling on said pan is moved toward tioned above said bed; a pipe connected to the discharge of said water motor, said pipe extending through said bed and having an outlet in said enclosed space of variable volume; and a member connected to said pan and passing through said pipe, said member being connected to a movable part of said water-driven motor for reciprocation thereby in a vertical direction.

3. A jig comprising in combination: a stationary screen; a permeable bed of. particles supported by said screen; 'a pan having a bottom in the form of an inverted flat cone having an outlet opening in the center thereof, said bottom sloping downwardly toward said outlet opening at an incline which would normally be insufllcient to cause concentrate particles settling on said bottom to move toward said outlet opening; an expansible connection between said pan and said screen forming an enclosed space of variable volume between said pan and said screen; reciprocating means connected to the bottom of said pan for vertical reciprocation thereof, the bottom of said pan being constructed of relatively flexible material of such character that application thereto of forces sufficient to reciprocate said pan causes the bottom thereof to be distorted to such an extent that concentrate particles settling on said pan are moved to said outlet opening by reason of said distortion.

4. A jig comprising in combination: a stationary screen; a permeable bed of particles supported by said screen; a pan positioned below said screen and having an outlet opening in the bottom thereof, the bottom of said'pan sloping downwardly toward said outlet opening at an incline which would normally be insufficient to cause free movement of concentrate particles to said outlet opening; an eXpansible connection between said pan and said screen forming an enclosed space of variable volume between said pan and said screen; the bottom of said pan being constructed of relatively flexible material of such character that application thereto of forces sufficient to reciprocate said pan causes the bottom thereof to be distorted to such an extent that concentrate particles settling on said pan'are moved to said outlet opening by reason'of said distortion; and reciprocating -means connected to the flexible portion of said-pan for vertical reciprocation of said pan.

- MAX KRAUT.

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