US2341662A - Apparatus for separating loose masses - Google Patents

Description

c. SCH-OUTEN ,34

APPARATUS FOR SEPARATING LO OS E MASSES Filed Jan. 24, 1940 Patented Feb. 15, 1944 APPARATUS FOR SEPARATING'LOOSE MASSES Cornelis Schouten, Delft, Netherlands; vested in the Alien Property Custodian Application January '24, 199A SerialNo. 3115;426

' In the Netherlands January 16,1-939' 1 Claim.

The inventionrelates' to improvements in apparatus for the separation of solidparticlesfrom loose masses, particularly ore-bearingmaterials, for example,- alluvial, eluvial or crushedprimary ores, according to-their specific gravity and grain size, such apparatus being ofthe-kind known as shaking tables in which aloose mass in awet state is subjectedto a reciprocatory or agitating movement over an-imperv-ious bedor bottom; In one well-known form of apparatus, the material is fed over an impervious, usually rifiied, table subjected to a reciprocatory and: d-ififerential movement and'wa'shed by a-film of water flowing at right angles tothe'direction of motion. The major part of the material treated is discharged at oneof the lcngitudinal ends of the table, the material'being sorted by the movement of the table -inthedirection ofthe longitudinal axis-4n consequenceof the difference in specific gravity and grain size of the particles Separation in channel or launder systems-in so-called rheo laveurs'sluices, long-toms, etc., is in certain respects similar tothis'process, but presents in actual practice aiundamental distinction inthat it cpera-teswitha rapidly flowing stream of waterwithcut reciprocatory or agitating move-- ment. Ascomparatively solidrbed is formed on the bottom of the; channel or launder within which no further effective separation takes place, so that a ,cleanseparation .of unclassified or lunsizedvmateriallpractically cannotbe obtained to an. efiicient extent.

The cperaticn of jigsris :based. upon .a reciprocating. motion ofrthegranular mass supported on a screen by upward impulses of water currentsat regularlyrecurrentintervals. The tailings and the specifically: heavyconcentrate may in some cases .both :bedischarged principally in the hori zontal direction .(gate;.and. damsdischarge) in general, however, themajor portion .of the mass is principally discharged in the horizontal direction, whilethe concentrate is drawn off in the vertical direction'through .the screen. However, the concentrate alwaysc travels to the .point of discharge :underthe actionof a current vof water pulsating through i3 perforated plate on screen; The jig is usefulfordealingiwithcoarse grained material but is less suitabledfor-handling fine grained material because the. capacity isthen considerably reduced and the upwardly directed currents of watermay easily cause very fine particles of high specificgravity to enter the specifically lighter mass whichis discharged.

The shakingtable;.afiords very. great advantages in the separation fine material, namely an effective separation and easier recovery of fines than'jin a'jig. However, the table a lsopresents disadvantages. The capacity per unit of surface area ("or per square metre) is very low. Previous classification in hydraulic classifying apparatus or spitzkasten is desirable in order to obtain good results. Relatively coarse material isdifiicult to treat ona shaking table. The up perlayers of the mass must bedischarged'in the directio'n'inwhich the masstravels over the table on which the separation takes place; owing to the-agitating and-insome cases differential move ment in order that the concentrate may be re'- tain'ed: Due partly to thedifferential movement of theta'bleand partly to the action of the cross wash of water; separation'takes place in a lateral direction" along the path-of travel. However, the concentrate musttr'averse' the entire length of the' table in order" that it" maybe withdrawn: The danger then arises-of the specifically heavy constituents being washed out of the relatively thin bed.-- Shaping of; the surface ofthe table, such ast-he' provisionof rifi1es,-has not always been found "suificientto prevent this; Consequently, losses =ofconcentrate occur, particularly of-extr-emely fine material in the rifiled, but also of relatively coarse materials in the unriiiledpart ofthe table-deck.-

- The invention overcomes these disadvantages bycombining toa certain-extent a'sha king' table with ajig. Accord-ingly,. the present invention comprises a processfor-the separation of" solid particles "according to their specific gravity and grain size; of the ki'nd i-n whicha leose mass of material in a wet state travels over an impervious surface o-r bed -in a substantially horizontal or slightly inclined dire'cti'on-whi1e being subjected to a reciprocatory or shaking and difie'rentialmotion wherein the gener-al directionof transport of the main mas's --ofsolid material issubsta'ntia'lly the sameasthe directiorr of -travel for discharge of the "heavier particles on concentrate, and wherein heavier-particles or concentrates passing downwards' in the =ma'ssare discharged at one or-mor'eintermediate-points in the path-of the loose material over said surface or bed through openings are subj ected from -loielow to a*- hydraulic,- if desired;- pulsating counter pressure.- Preferably; the mass o'f material (com'- prisinglth'e particles 'of"le'ss specific gravity) i and the concenti 'atare 'discharged at different levels; it thus being possible ior -the bed? to be -much thicker than in the areer kricwn'types or shakingstablesz K a The PIOCGSS- 'aCGOXdlIIE to the invention toa certain extent thus combines the advantages of the jig and of the shaking table, and has the object of eliminating the disadvantages of these apparatus as far as possible. It permits of recovering relatively coarse to relatively very fine particles of high specific gravity such as gold, platinum, cassiterite and the like with very small losses. This highly selective extraction is accompanied by a large capacity and considerable concentration, while the water consumption is very low.

By the term concentrate as used herein is meant the enriched specifically-heavy constituents, regardless of whether they are valuable, valueless or even harmful.

A constructional form of the apparatus according to the invention is shown with various details in the accompanying drawing, in which:

Figure 1 shows the apparatus in longitudinal section,

Figure 2 is a plan view,

Figure 3 is a sectional view of a discharge arrangement with corresponding stand pipe,

Figure 4 is a modified constructional form of the 'point of discharge, and

Figures 5 and 6 show a somewhat modified constructional example of a discharge arrangement in section corresponding to Figure 1 and in plan view respectively.

Referring to Figure 1 of the drawing, the numeral I designates a substantially trough-shaped container having an impervious bottom interrupted only by one or more points of discharge intermediate its length. This container is rectangular in plan view, as is shown in Figure 2. The mass to be dressed is fed by means of a hopper 2 and withdrawn at the discharge end. The trough is suspended by a series of pivoted links 4, 5 mounted on shafts 6 and 1 respectively and may consequently be rocked to and fro, for example by means of an eccentric 8 coupled With an eccentric rod 9 engaging at a point of rotation 10. A differential movement or a percussive action may sometimes be applied. Due to the suspension of the trough on links 4, 5, the movement also has a vertical component which may be regulated by correct selection of the inclination and of the length of the links 4, 5. The links may be of different lengths in order that the movement imparted to the container may not be completely parallel and are preferably so arranged (i. e. of a length which decreases in the series from the feed to the discharge end) that the vertical component of movement increases from the feed to the discharge end of the trough. The links may be adjustable in length.

Owing to the reciprocating motion, the mass is moved through the trough from the delivery end to the discharge end. The surface of the bed of material is somewhat irregular and will generally follow the course of the bottom. The surface will generally follow the line lli I. The mass is preferably provided with an ample amount of water, but not with so,muoh that the washing takes place as in rheo-laveurs sluices or long toms.

-The reciprocating motion of the container causes the specifically heavy constituents of small grain size to pass downwards through the coarser mass, so that these constituents are concentrated at the bottom of the container. Various measures may be applied to assist this separation, while care must be taken at the same time that the mass remains sufiiciently loose or alive. .To this end,v a wall |2 and .difierent groups of 2,341,662 '1 i .ii'?

pins [3 are provided. The said wall has a direct influence on the mass delivered, on which it exerts a damming effect in the directon of the bottom of the container. It may at the same time serve to prevent any splashing action of the water. The pins l3 are inclined in the direction of the bottom of the container and in the general conveying direction. 'They' could naturally also be arranged on the bottom of the container itself and could be replaced by walls or similar members.

The bottom of the container extends downwards in the direction in which the mass is conveyed to the points of discharge, as at I5 and I6. The descent is somewhat gradual and the concentration is particularly great at these points. The bottom parts l5, l6 are preferably provided with transverse strips or rifiles, for example in the form of steps, in order that the concentrate formed may not have any tendency to return or to mix with the remaining mass I under the action of the reciprocating movement. At the same time, the steps assist the'forward movement of the material in the lower layers in the direction of the points of discharge.

In this way, a somewhat large quantity of concentrate, which also contains the finest grain parts and is greately enriched, may be discharged from the relatively thick bed of large conveying capacity at the end of the bottom parts l5, 16, for which purpose the discharge points 20, 2! are provided, which are fashioned in the manner of slots extending transversely through the apparatus. Immediately behind the points of discharge 20, 2| the bottom of the container again extends upwards, either somewhat vertically or at an incline. It is obvious that concentrates of different composition and different structure may in some cases be discharged at the different points of discharge.

The form of the points of discharge may vary per se. Generally, the discharge apertures 20, 2| will be partly closed by obturating members which leave certain small, if necessary gap-like apertures permitting of the passage substantially solely of the particles of the desired grain size of the material intended to be extracted. According to Figure l, sharp-edged sheets or plates 22 and 23 are provided in the lateral edges of which narrow gaps are left for the passage of the specifically heavy constituents. These sheets 22, 23 could be combined with or replaced by gratings or perforated plates andif desired a shot-or mineral-bottom bed or the like could be provided thereon as shown at 23.

The water which flows from the apparatus with the specifically heavy constituents through the discharge points 20, 2| may be regulated in any desired manner. Thus, it may be desirable to oppose the hydrostatic pressure inside the container by a counter hydrostatic pressure. This may be achieved by suspending the entire container in a water bath. If, in this case, the water bath is fixed (which, however is not necessary) a pulsating water movement through the discharges 20, 2| will at the same timebe produced owing to the movements of the container, which is very favourable to the constant loosening of the bed and of the discharge chambers and discharge points.

Moreover, stand pipes may be provided at the points of discharge as is shown in Figure 3. A vertical channel 25 tapering in the manner of a hopper or spigot may then be provided for example,. below, the plate .orsheet. 22, this channel being connected to a tubular rubber member 26 adapted to follow the movements of the container I. On the other hand, the tubular rubber member 26 is fitted over the fixed element 21, which is provided with an upwardly extending stand pipe 28 attached laterally thereto. A tube 29 having an overflow 30 and a water supply 3| is telescopically arranged thereon. The height to which the tube 29 is adjusted determines the height of the water column, the pressure of which acts on the point of discharge 20. The particles of the ore passing the sheet 22 may be finally withdrawn through the branch pipe 32. If desired, a pressure water pipe could also be made to open into such an apparatus for the purpose of periodically or continuously washing through the discharge points.

A further constructional form of a discharge point is shown in Figure 4. The slot is here covered by a curved sheet 40, in the front side of which a gap 4| is left, through which the concentrate below a certain grain size may leave the container I. Here again, a sheet 22 having gaps in its longitudinal edges is provided. This sheet co-operates with a perforated plate 42. Arranged on the sheet 22 are one or more series of balls 43 which are themselves in constant movement owing to the movement imparted to the container. The shocks thus exerted on the sheet 40 have a favourable effect on the discharge.

The sheets 22 may be replaced by corrugated sheets 25 as shown in Figure 5, apertures here again being left in the longitudinal side. For this purpose, recesses 46, 41 are in this case provided only in the troughs of the corrugations. The crests of the corrugations are not recesses but extend through to the lateral edges of the discharge branches. The corrugated form of the sheet 45 affords the advantage that a certain separation is efiected on this sheet 45, since the specifically heavy constituents collect in the troughs, so that discharge is efiected only therefrom. Here again, balls may be loosely arranged above or below the sheet 45, which exert an impulsive action.

The discharge points may be provided at different positions of the closed bottom of the container l. Thus, the first discharge could in Figure 1 also be arranged at the point 58. The number of discharge points depends upon the circumstances, in accordance with which one or more are provided.

The width of the container has no efiect on the eficiency of the separation, but only affects the capacity of the apparatus.

What I claim is:

An apparatus for the separation of solid particles according to their specific gravity and grain size, respectively, from loose masses, comprising a trough shaped container, having walls and bottom impermeable to liquid and being arranged at one end for the feed to be treated and at the other end for the tailing discharge, and means for reciprocating said container, a portion of the bottom of said container being inclined slightly downwards in the direction from the feed to the discharge end of the container and having at its lower end a localized discharge zone for continuous extraction of the concentrate, the area of which is only a minor part of that of the inclined bottom portion and said discharge zone being subdivided into small passages so as to act as a sieve, means comprising a U-shaped duct being connected to the discharge zone from below for hydraulically balancing the head of the liquid in the container above the said discharge zone by a pulsating counter pressure to produce a jigging action at the discharge zone, said container being suspended upon a series of pivoted hangers the length of which decreases in the series from the delivery to the discharge end of the container.

CORNELIS SCHOUTEN.

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