Mineral separation apparatus

Abstract

An oscillating mineral dressing table which may be easily adapted for automation, and provides for continuous particle concentration, classification, sizing, shape sorting and flotation. The mineral separating apparatus provides an elongated planar porous member which is inclined to the horizontal and vertical planes. Mineral feed is introduced along the higher lateral side of the porous member and the mineral is separated by oscillating this member in the direction of the lateral side through a liquid medium. By this mechanism the coarsest highest density particles are caused to climb up the lateral incline of the porous member whilst the finer less dense particles are displaced to the lowest end of the member. The mineral process flow is transverse to the direction of oscillation, that is, in the longitudinal direction of the porous member. The application of the dressing table with its multi-range of operational variables and its increased sensitivity is particularly suitable for increasing the usable output of lean mineral feeds.

Description

This invention relates to separators and more particularly to vibrating mineral dressing tables.

In general, many industries suffer from the lack of a machine which will

A. CONCENTRATE AND/OR CLASSIFY WITH SUFFICIENT SENSITIVITY COARSE SIZED MINERALS SUCH AS MINED ROCK, GRAVELS AND THE LIKE;

B. CONCENTRATE AND/OR CLASSIFY WITH SUFFICIENT SENSITIVITY IN THE CRUSHING SECTIONS OF TREATMENT PLANTS;

C. DETERMINE OR HELP DETERMINE THE "GRAIN SIZE" OR "LIBERATION" CHARACTERISTICS OF MINERALS AND THE LIKE, PARTICULARLY DURING PROCESSING;

D. INCREASE THE CLASSIFICATION, GRINDING, FLOTATION EFFICIENCIES OF MINERAL TREATMENT PLANTS AND THE LIKE.

The above are only a few examples to illustrate the need for new methods and machines. It is the object of this invention then, to provide the primary, secondary, building and construction industries with:

A. a gravity concentrating machine for general application.

B. a gravity classifying machine for general application.

C. a sizing machine for general application.

A shape sorting machine for general application.

E. a flotation machine

F. a machine capable of providing accurate and/or relative liberation characteristics of minerals, mineral particles and the like for "on stream" control of plants either under computer or manual control, for research or the like.

G. a machine capable of providing advance information of flotation and/or gravity recovery patterns so that process controls can be varied within sufficient time to provide optimum or improved recovery or throughput or the plant.

H. a machine capable of concentrating, classifying and/or sizing minerals and such like from alluvial and hard rock mining, from boulder size through gravels, crushed rock and fines. In addition to the above sub-paragraphs a, b, c and d, this application and methods of the present invention is aimed at decreasing the "cut off" grade of a mine, ore deposit and the like, thereby increasing the reserves and follow on values.

i. a machine capable of classifying and/or concentrating minerals in the crushing circuits of mineral treatment plants and the like, such that:

1. general crushing can be extended to finer sizes.

2. fractions of mineral sizes that would be best suited for coarse ball milling, fine ball milling or the like, and finished product. Such fractions would then be sent to appropriate machines thus by-passing the rod mill process and thereby increasing plant efficiency, capacity and throughput.

3. concentration of liberated minerals and the like can be achieved e.g., tin circuit, so that sliming loss ocasioned by unnecessary further comminution (rod or ball milling) is avoided thereby increasing recovery and plant profitability.

j. a machine capable of classifying and/or concentrating a ground mineral product or the like, particularly a rod mill product, such that fractionation of particles coarser than efficient operation of current cyclones or classifiers and processing through mills best suited for such sizes results in improved efficiency and/or throughput. Likewise, overgrinding of coarser liberated particles is minimised.

k. new methods of treatment of minerals and the like arising from the invention. These new methods are generally covered by sub-paragraphs f through to j above, either singularly or in multiple combinations thereof.

Two particular features of the present apparatus are the sensitivity of the apparatus and the range of operational variables. Such variables include: variable fluid flow, variable densities and viscosities of fluids by initial selection, variable speed and amplitude of deck oscillation, range of sieves and variable deck path geometry (including longitudinal incline, lateral incline, angle of oscillation -- equal on radii, angle of oscillation -- unequal on radii, equal length radii for oscillation, unequal length radii for oscillation). Since the sieve or porous member is elongated in shape preferably rectangular, the terms `longitudinal` and `lateral` are herein used refer to longer and shorter lengths or axes respectively of the sieve or porous member. The apparatus is designed on the maximum utilisation and application of these variables to produce the sensitivity of separations or of deliniations for the most difficult application, namely, relative liberation parameters. The application of the apparatus then, is for the functions of gravity concentration, classification and sizing, shape sorting, and flotation with application in the primary, secondary building and construction industries. Due to the characteristics and applications of the machine, new methods for treating fractured rocks, gravels, mineral particles and the like are established.

Broadly, the apparatus of the present invention provides a mineral separating apparatus comprising a housing containing therein a substantially elongated planar porous means, said porous means being inclined relative to the horizontal and vertical planes such that there is an upper and lower lateral and longitudinal side, means for adjustably controlling the said incline of the said porous means, oscillating means to oscillate said porous means in a direction parallel to the lateral side, a power means connected to said oscillating means whereupon initiation of said power means said porous means oscillates in a substantially sinusoidal or arcuate path, said porous means being further immersed in a body of liquid such that by the action of the oscillations and said body of liquid mineral feed which is introduced onto said porous means travels upwardly on the porous means in a direction substantially parallel to the lateral side whereby the coarsest highest density particles of the feed are arranged substantially along the upper longitudinal side whilst the fine least dense particles are arranged along the lower longitudinal side, and whereby the material product travels downwardly in a direction substantially transverse to the direction of oscillation to discharge at a product outlet.

More particularly, the machine of the present invention can be likened to a rectangular box, or upper container inclined in the horizontal plane along both the longitudinal and lateral axis, with a porous screen fitted at the bottom thereof. The incline of the upper container and screen thus effectively provides relative to a horizontal plane, a high and low side of the longitudinal or longer sides and a high and low side of the lateral or shorter sides of the upper container and screen. The screen, with the aid of upward rising fluid, provides a support for the mineral particles. The upper container including the screen oscillates in the lateral direction which largely gives rise to particle separations, while the longitudinal incline gives rise to process flow. The oscillation of the upper container and screen cause these integers to scribe a substantially sinusoidal or arcuate path. This oscillating action combined with an upwardly rising body of liquid results in the heaviest densest particles climbing upwardly in the lateral direction, that is, in the direction of oscillation whilst the finer less dense particles are displaced to the lowest lateral end of the screen.

The mineral process flow is in the direction of the longitudinal side, that is transverse to the direction of oscillation, and as such indicates a time constant of the particles on the screen.

Material to be treated is introduced onto the upper inclined longitudinal end of the deck box and the products are removed from:

a. the other end of the deck box, where splitters keep the products separate (concentration, classification, sizing)

b. the deck box fluid overflow (classification, density, separations, flotation)

c. from the under deck or liquid distributor (jigging arrangement)

The fluid utilised in this process could include for example, water, hydrocarbons and other such liquids, "heavy liquids" e.g., tetrabromoethane, bromoform and such like, heavy liquids such as water or hydrocarbon base and such like containing dissolved salts, and suspended particles commonly referred to in the art as "heavy media". When this apparatus is used as a flotation machine, gas (usually air) is also introduced with the fluid, under the porous screen.

The invention will now be more particularly described by way of example only, with reference to the accompanying drawings wherein:

FIG. 1 is an end elevational view of one form of the invention.

FIG. 2 is a plan view of the invention in FIG. 1 with the screen and base removed to more clearly show the liquid inlet and the dense "fines" product outlet.

FIG. 3 is an end elevational view of another form of the invention with the hopper discharge removed for clarity.

FIG. 4 is a plan view of the invention in FIG. 3.

FIG. 5 is a perspective view of the invention of FIGS. 1 and 2.

FIG. 6 is a perspective view of the invention of FIGS. 3 and 4 with the screen removed to more clearly show the base.

To simplify the description, identical numerals will be used throughout the specification to designate identical integers of the invention.

Referring to the drawings, and in particular to FIGS. 1 and 2, the framework in general consists of two sections. The first is a main frame section which provides a base for siting and indirectly fastening the apparatus of the present invention to the appropriate foundations. The other is the sub-frame section, to which the apparatus is directly fastened. The sub-frame section then, is pivotly connected above the main frame section by means of adjusting screws or hydraulic or pneumatic rams which may be locked in any desired position. By altering the position of the subframe relative to the mainframe, any appropriate longitudinal incline of the deck may be achieved.

The fluid containing under deck distributor box with its associated centrifugal pump and ducting means is attached to the fixed mainframe section. Whilst mounted on the adjustable subframe is an oscillator apparatus together with its motor and associated drive train.

For the sake of simplicity the mainframe and subframe sections have not been illustrated in the drawings. However, the frames should preferably be fabricated from steel unless the apparatus is used in a corrosive environment, wherein special precaution may be necessary. In general however, the framework especially the mainframe, should be of sufficient mass to absorb the vibration caused by the oscillating deck. Fabrication section could be angle, channel, hollow rectangular, I-beam and plate depending on size and duty.

More specifically, the apparatus of the present invention provides an assembly 10, which includes an upper container or deck box 19, and a lower container or liquid distributor 23. Separating the deck box 19 from the liquid distributor 23 is a base 21 over which is tightly stretched a screen 20. As may be seen from the plan view in FIG. 2, the deck box 19 is of rectangular shape, however in elevation as may be seen from FIG. 1 one side wall along the longitudinal length of the deck box is higher than the side wall of the adjacent longitudinal length. A weir overflow 29 is situated on the higher side wall along the longitudinal side wall of the deck box 19 and a liquid outlet drain 30 is positioned directly adjacent the weir 29. The base 21 has a planar rectangular configuration and is inclined in the horizontal plane along both the longitudinal and lateral axis when positioned in the deck box 19. As mentioned previously the incline in both the longitudinal and lateral direction effectively provides, relative to a given horizontal plane, a high and low side along both the longitudinal and lateral sides of the base 21 and screen 20.

The screen 20 may be made from any convenient porous material such as woven metal, rubber or plastic; punched plate; sintered metal or porous plastic. However aperture size of the screen should be sufficiently large as to avoid clogging or blinding by the process mineral.

In one form of the embodiment (FIGS. 1 and 2) the container base 21 connects the lower deck or liquid distributor 23 by means of a flexible saw-tooth member 44 made of any convenient material such as rubber ply. The lower container 23, which is immovably contained in the main frame assembly is a simple bin structure with a converging bottom. Along one side of the sloping bottom are connected fluid inlet tubes 25, whilst along the other sloping side at the point of convergence of the sloping sections, are connected several off-take product outlets 24.

Product discharge hoppers 22 are attached to the lower end of the base 21 and along the lower most lateral side of the deck box 19. Attached to the top of the deck box 19 at the product discharge end, is also a splitter support bar 36, which supports splitters 38. The splitters 38 are substantially inverted T-shaped plates whereby the lower end of each plate extends into the discharge hopper 22 whilst the upper end is allowed to slide along the support 36 to divert the different mineral fraction into separate product discharge hoppers 22. The splitters 38 seal against the screen 20 and are further held in position by any convenient fastening means (not shown) which may be attached to the splitter support bar 36.

The product discharge is by the hoppers 22 for the fine fractions of mineral, however for the larger fraction sizes because the hopper opening may be too small, continuous elevator bucket (not shown) may be employed. The elevator bucket may be a separate motorised unit mounted to the sub-frame with adjustable means for controlling the positioning and the speed of rotation. The bucket then extends from the hopper and catches the larger mineral particles, to later deposit them onto a conveyor system. The drive for the elevator may be attached to the top pulley of the elevator system such that the lower pulley runs in the mineral fraction and fluid. Needless to say all bearings should be suitably sealed against entry of the fluid or solid to prevent damage.

The vibrating mechanism includes an eccentric shaft 13 which is of robust constructions to prevent secondary vibration of the deck box 19 containing the base 21 and the screen 20. The shaft 13 is mounted to the sub-frame via sealed anti-friction bearing and housing arrangements 37. These shaft bearings 37 are located close to each side of the two connecting rods 14 to aid in preventing shaft deflections. The shaft 13 may also be fitted with two or more anti-friction eccentric bearings and a driven sheave or coupling if required.

The pivot arm arrangement consists of an outer arm 16 and an inner arm 17, and the machine generally carries two or more sets of these arms depending on size and weight of the deck box 19. One end of each of the outer pivot arms 16 is attached to a connector rod 14. One end of the inner pivot arms 17 is attached to the longitudinal side of the deck box 19 via lugs 45. The other ends of the pivot arms 16 and 17 are mounted to a common pivot shaft 28. The inner arms 17 being firmly fixed to the shaft 28 while the outer arms 16 are mounted on bushes or bearings so that both the arms can be adjusted inwardly or outwardly in relation to each other by means of a pivot arm adjusting link 18, to provide variation for angle of deck oscillation. The inner pivot arm 17 is yolked at the shaft end, and acts as a thrust bearing for the outer pivot arm 16 which is also fitted onto the pivot shaft 28 between the yolk of the inner pivot arm 17.

The pivot arm shaft 28 is robust and should also be supported by anti-friction bearings 37 on either side of each of the two or more pivot arms 16 and 17 further at intermediate locations if necessary on the large machines. As previously stated the shaft 28 is mounted to the sub-frame such that one or more of the anti-friction thrust bearings carry the thrust imposed by the longitudinal incline. By appropriate adjustment of the pivot arms, incline of the deck 10 can be varied in the lateral direction i.e., angle ABC in FIG. 1 which controls the angle of oscillation can be varied.

The connecting rods 14 transmit the power and convert the motion from the eccentric bearings 12 to the pivot arms 16 and 17, such that the deck box 19 which contains the base 21 and screen 20 is caused to oscillate. Preferably, also provision is made on the connecting rods 14, for altering the point of attachment of the outerarms 16 to provide the variation in amplitude of oscillation. Alternatively and/or in addition, adjustable eccentric anti-friction bearings (e.g., double eccentric) may also be installed to further extend the adjusting range of the amplitude of the deck box 19. The connecting rods 14 should be rigid and to achieve the lightest weights, aluminium alloys, steel hollow or I-sections may be used.

Left and right hand threaded adjustment rods 18 with a corresponding nut and lock nut further provide means or power transmission and angle of oscillation adjustment. The rods 18 are made free from flex and are as light as possible but consistant with strength and rigidity.

On the side of the deck box 19 opposite the pivot arms, are the idler arms 26 which support the upper longitudinal side of the deck box 19, via lugs 45. The other ends of the idler arms 26 are connected to a support 27 which is adjustable by threaded rods and nuts in the vertical and horizontal planes to provide variation in the angle of deck incline and angle of oscillation respectively. These arms 26 are in the form of rods with left and right hand threads and they also include corresponding nuts and lock nuts to provide adjustable variations in the radius of oscillation. The rod attachments at the deck box 19 and support 27 include, again sealed bearings or bushes and pins.

The centrifugal pump installation consists of a hopper, motor drive and pump, control valves, by-pass lines and delivery piping manifold and the like, all generally mounted to the main frame. The hopper 31 receives liquid from the liquid outlet drain 30, from a make up liquid supply mains via tubing 35 and from the pump closed circuit by-pass line 34. The hopper 31 would generally be fitted with a level control valve on the make up liquid supply mains to stabilise the pressure head on the pump 32 thereby minimising surging within the liquid distributor 23. The pump 32 should also preferably be matched to the specific delivery specifications for each application and would generally be a centrifugal type suitable for slurry operations. The motor may be a constant speed type motor or a D.C. variable speed type with controls to compliment the range of fluid supply which would help minimise liquid surging by closely matching the impeller speed required. The delivery pipeline 33 comprises a manifold arrangement with distributing baffles at each inlet 25 to distribute the fluid more evenly throughout the distributor 23.

Generally the machine can be fitted with calibrations and instruments to enable setting of controls to known or trial settings. For automatic control and computerisation, the machine can be fitted with sensors for every variation such as flows, speeds, linear measurements, geometric angles and such like.

Power supply is normally electric however provision can be made for alternate sources. The motor 11 for the eccentric drive 13 can be mounted to the sub-frame or elsewhere as appropriate. Transmission of power is by conventional sheaves and belts (V, poly-V, gear type) unless large designs demand direct shaft couplings via running in oil reducer drive.

Referring now more specifically to FIGS. 3 and 4, this alternative embodiment is aimed particularly for automation.

In this design, the base 21 is itself the distributor individually and consists of a plurality of individually sealed channels (not shown) each connected via flexible hosing and including volume control valves to the pump discharge or mains manifold. The deck box 19 is made as light as possible and constructed in steel, aluminium or its alloys, fibreglass or the like. The deck box 19 is connected to the base 21 by means of suitable quick release clamps which in so doing, positions and seals the porous screen therebetween. This arrangement facilitates quick changing of the porous screens to meet any new desired needs or in the event the screen becomes damaged.

In this arrangement also the pivot arms which are actually rear idler arms 40, connect at one end to lugs 45 located on the upper longitudinal side of the upper deck box 19, and at the other end to base block 43. The opposite longitudinal side of the deck box 19 is similarly supported by a front idler arm 39. The arms 39 and 40 are hydraulic rams which do not transmit power but merely support the deck box 19 and its load. The rams however, do provide a means for variation of the radius of deck oscillation and lateral incline angle of deck base 21 by variation of the idler arm length. It should be noted that in this arrangement either the bases for the idler arms 39, 40 can be made variable in the lateral direction by hydraulic rams such as ram 41 while maintaining a fixed length on the connecting rod 42; or the connecting rod 42 can be made variable in length to achieve the same effect. In any case either the front idler arm base (not shown), or the rear idler arm base 43 can be made variable to provide suitable means for variation of the angle of oscillation of the deck box 19 via rams 39 and 40. Still further variations in the angle of oscillation may be achieved by manipulation of the hydraulic ram 42.

The above embodiment, then is particularly suitable for automation because of the relative ease in which all the variables may be controlled through say a programmed computor or such like central control device.

Referring particularly to FIGS. 1 and 2; in operation then, the sub-frame section is adjusted via the hydraulic means relative to the mainframe to provide the desired longitudinal incline. Next, the lateral incline is adjusted via the adjustable idler arms 26. Then, the angle of oscillation is adjusted via the pivot arm adjusting link 18 and the horizontal adjustment of support 27. In the case of the embodiment of FIGS. 3 and 4 appropriate adjustments are made via the hydraulic rams 39, 40, 41, 42 and 43. Fluid is then cycled through the system, the splitters 38 set to divide the appropriate sizes and the deck box 19 initiated to oscillate.

The mineral is fed to the upper lateral side of the screen. Due to the oscillation motion of the deck box 19, that is, the angle DBC of the screen and the angle ABC of the oscillation, the larger and consequently heavier minerals are found to separate upwards towards the right hand side of the screen 20 in FIG. 1, whilst the smaller and lighter particles separate at the left hand side of the screen 20. The longitudinal incline of the deck box 19 including the base 21 and the screen 20 provides process flow and the fractions separate into the various collecting hoppers.

The upward flow of the fluid tends to lower the relative specific gravity of the minerals such that the lighter particles e.g., "slimes" are washed over the weir 29 and into the channel 30. These slimes may then be fed through a cyclone to separate out the heavier particles, before the remainder of the fluid is returned into tank 31. It has been shown that a considerable economical saving in minerals may be achieved by this procedure. As mineral deposited in the hoppers 22 builds up, the fluid flow rate may be reduced as required. As explained earlier, if the hopper capacity is insufficient for the larger fractions a bucket elevator may be used to collect and redirect this fraction onto a conveyor system.

The third source of mineral fractions collected from the apparatus is through outlet 24, whereby opening this outlet at the appropriate intervals, very fine but dense particles that had fallen through the screen 20 are collected, again achieving mineral separation. The separated functions of minerals can further be separated by the apparatus of the present invention into various shapes of minerals. It has been found that longitudinal or spherical particles tend to climb up the lateral incline more readily than tabular particles which tend to gather at the lowermost portion of the screen 20. By using appropriately designed screens e.g., larger apertures at the high lateral inclines, smaller spherical particles may be collected via outlet 24.

Since various changes may be made to the hereinbefore described apparatus, it is intended that all matter contained in the above description and as shown in the accompanying drawing shall be interpreted merely as illustrative and not in a limiting sense.

Claims

What I claim is:

1. A mineral separating apparatus comprising a housing containing therein a substantially elongated planar porous means, said porous means being inclined relative to the horizontal and vertical planes such that there is an upper and lower lateral and longitudinal side, means for adjustably controlling the said incline of the said porous means, oscillating means to oscillate said porous means in a direction parallel to the lateral side, a power means connected to said oscillating means whereupon initiation of said power means said porous means oscillates in a substantially sinusoidal or arcuate path, said porous means being further immersed in a body of liquid such that by the action of the oscillations and said body of liquid mineral feed which is introduced onto said porous means travels upwardly on the porous means in a direction substantially parallel to the lateral side whereby the coarsest highest density particles of the feed are arranged substantially along the upper longitudinal side whilst the fine least dense particles are arranged along the lower longitudinal side, and whereby the material product travels downwardly in a direction substantially transverse to the direction of oscillation to discharge at a product outlet.

2. The apparatus as claimed in claim 1 where there is provided means for controlling the amplitude of said oscillation and a means for controlling the speed of oscillation.

3. The apparatus as claimed in claim 1 wherein the said means for adjustably controlling the incline of the said porous means is a screw means and the oscillating motion is controlled by pivot arms attached at one end to an eccentric shaft and the adjacent end to the longitudinal side of said porous means.

4. The apparatus of claim 1 wherein the said body of liquid is a rising body of liquid introduced to the said housing through a manifold connected to a distributor portion of said housing located beneath the said porous means, such that liquid passes through said porous means to a liquid outflow in the form of a weir located along one or more sides of the housing above the said porous means.

5. The apparatus as claimed in claim 1 wherein the body of liquid is water.

6. The apparatus of claim 1 wherein the planar porous means is a rectangular sieve.

7. The apparatus as claimed in claim 1 wherein the said means for adjustably controlling the incline of the said porous means are hydraulic rams and the oscillating motion is controlled by a hydraulic ram connected at one end to an eccentric shaft and at the adjacent end to the longitudinal side of said porous means.

8. A method for separation of mineral feed in an oscillating apparatus comprising the following steps:

adjusting the incline of a substantially elongated planar porous means such that said porous means is inclined relative to the horizontal and vertical planes whereby the porous means has an upper and lower lateral and longitudinal side,

initiating a power means to oscillate said porous means in a body of liquid along a substantially sinusoidal or arcuate path said oscillations being in a direction parallel to the lateral side,

and introducing the mineral feed onto said porous means whereupon the mineral feed travels upwardly on the porous means in the direction of the lateral side such that the heaviest fraction of the feed is arranged substantially along the upper longitudinal side and said mineral further travels downwardly in a direction substantially transverse to the direction of oscillation to discharge at a product discharge.

9. The method as claimed in claim 8 wherein finest highest density particles of the mineral feed are collected at the bottom of said housing and finest least dense particles of the mineral feed are collected at the overflow of the rising liquid discharge.

10. The method as claimed in claim 8 wherein the said body of liquid is a rising body of liquid passing through said porous means.