AU780807B2

AU780807B2 - Stepped fluidised bed concentrator

Info

Publication number: AU780807B2
Application number: AU97392/01A
Authority: AU
Inventors: Clyde Ian Doxford; Ross James Thomas
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-01-05
Filing date: 2001-12-24
Publication date: 2005-04-21
Anticipated expiration: 2021-12-24
Also published as: AU9739201A

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION Invention Title: STEPPED FLUIDISED BED CONCENTRATOR The following statement is a full description of this invention, including the best method of performing it known to me: 2 STEPPED FLUIDISED BED CONCENTRATOR FIELD OF INVENTION This invention relates to mining equipment in particular but not limited to a stepped fluidised bed concentrator for the recovery of heavy, coarse and fine concentrates from ores by way of dry gravity separation.

BACKGROUND OF THE INVENTION Prior art devices for dry gravity separation of materials of higher specific gravity from materials of lower specific gravity are well known. Most of these prior art separators utilise air pulsating through an inclined screen bed with spaced riffles to separate heavier concentrates from waste tailings of lower specific gravity. There are also dry gravity separators that involve the creation of a fluidised bed over a large horizontal screen surface but which throughput is limited because of difficulties associated with the clearance and disposing of the waste materials. Other problems Si associated with prior art dry gravity separation devices include high operating energy requirements and the production of environmentally unacceptable levels of dust and air borne particulate matter.

OBJECT OF THE INVENTION It is an object of the present invention to seek to ameliorate some of the disadvantages of prior art dry gravity separation devices or to at least provide the public with a useful choice.

STATEMENT OF THE INVENTION According to one aspect, the invention resides in a stepped fluidised bed concentrator including in combination a concentrator deck comprising fluidising beds 3 of perforated sheet material, the sheet material configured to form a plurality of stepped portions, each stepped portion forming a horizontal, elongate fluidising bed, fluidising means adapted to pulsate fluid through the perforations of the stepped portions, riffling means positional along leading edges of each fluidising bed, the riffling means adapted to riffle dry feed material into a fluidised layer on each bed, wherein in operation, dry feed material is caused by the riffling means to remain on the fluidising beds for an extended period thereby improving separation of coarse and fine concentrates from waste and wherein the fine concentrates can pass through the perforations of each fluidising bed for collection and the coarse concentrates are captured behind the riffles while the waste discharges over the concentrator deck.

Preferably the perforated sheet material is stainless steel with suitably sized apertures for screening the intended fine concentrates. Typically for gold fines, the aperture diameter is between 0.2mm and 1.0mm and is optimally 0.4mm. Preferably the surface profile of the concentrator deck is planar however it can be convex or concave wherein the fluidising beds are always horizontal.

Preferably there are side plates on either side of the fluidising beds to prevent spillage of the fluidised layer at the sides or ends of each of the fluidising beds.

Preferably the riffling means is a ladder frame comprising a pair of arm members supporting therebetween a plurality of riffles of an angled or curved cross sectional configuration, the length and position of the riffles on the frame corresponding to the leading edges of the fluidising beds, wherein an angle or a curve of each riffle can be bought into contact with a corresponding leading edge to form a roofed or a coved ledge with the corresponding leading edge.

Preferably the riffles are right angle iron or steel however riffles of a different shape or cross sectional configuration can also be used.

Preferably waste discharges over the concentrator deck during normal operation.

Preferably the riffling means is disengageable with the fluidising beds to enable the cleaning of the beds including the build up of coarse concentrates behind the riffles. Preferably the disengagement of the riffling means from the fluidising beds is by way of hand operated lever and linkage means adapted to raise and lower the riffling means away from and onto the fluidising beds. Alternatively, mechanical, pneumatic or hydraulic means can be used to raise and lower the riffling means.

oooo Preferably there is a waste chute adapted to collect the waste at the end of the concentrator deck. Preferably there is a coarse concentrate chute adapted to collect bed material °o o°i and coarse concentrate discharge at the end of the concentrator deck. Preferably the fluidising means includes sealed oscillating diaphragm pump means located below and in sealed contact with the fluidising beds whereby fluid can be pulsated through the perforations of the fluidising beds. In the alternative, other types of pumps or means for pulsating fluid may be used.

Preferably the fluid being pulsated is air, however, fluids such as other gases or liquids can be used in the separation process.

Preferably there is a collection spigot adapted to collect fine concentrates passing through the fluidising beds at the base of the diaphragm of the oscillating diaphragm pump means.

Preferably there is a scarifying apparatus associated with fluidised bed concentrator, the scarifying apparatus adapted to oscillate from side to side to scarify the layer of dry feed material on each bed thereby improving the passing of fine concentrates through the perforations of the beds.

Preferably the scarifying apparatus comprises one or more longitudinal support members supporting a plurality of scarifying rods adapted to slide against or as near as possible to the perforated surfaces of the beds.

Preferably there is motorised means to oscillate the scarifying apparatus.

Preferably the scarifying apparatus can be raised clear of the concentrator for cleaning purposes.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention be better understood and put into practical effect, reference will now be made to the drawings wherein: 9 Figure 1 is a perspective view of the invention according to Example 1; Figure2isasideviewoftheinventionofExample;and Figure 2 is further side view of the invention of Example 1 and:.

Figure 3 is further side view of the invention of Example 1, and •t Figure 4 shows a preferred scarifying apparatus according to the invention.

DETAILED DESCRIPTION OF DRAWINGS Referring to the drawings and initially to Figure 1, there is shown a preferred stepped fluidised bed concentrator 10 according to Example 1 during normal operation. The stepped fluidised bed comprises a concentrator deck 12 with stepped portions of perforated steel forming a number of horizontal elongate fluidising beds 14,16 which form the concentrator deck 12. An oscillating diaphragm pump (not shown) located below the concentrator deck pumps air through the perforations of 6 the fluidising beds 14,16 on movement of the diaphragm 17 of the pump shown by arrow 18. Riffles 20,22 preferably comprising lengths of right angle steel are shown in contact with leading edges 24,26 of the fluidising beds wherein roofed or coved ledges 28,30 of approximately 20mm in height are formed which promote the formation and maintenance of fluidised layers of dry feed material (not shown) on each of the fluidising beds. The individual riffles are connected to connecting arm members 32 (one side shown only) to form a ladder type frame. Dry feed material containing coarse and fine concentrates, for example, gold is fed at the top of the concentrator as shown by arrow 38 and allowed to flow down onto the individual stepped portions 14,16. Fluidised layers of the feed material (not shown) are then formed on each stepped portion wherein the material is fluidised by air pumped through the perforations in the beds 14,16 and the fluidised layers maintained by the coved or roofed ledges formed by the riffles in contact with the leading edges of the beds. Fine concentrates are allowed to fall through the perforations in the fluidising beds wherein they can be collected by a collection spigot (not shown). Waste material can then be collected via a waste chute 40 at the end of the concentrator deck. Also shown are side plates 42,44 on either side of the beds to prevent spillage of fluidised material at the ends or sides of the beds.

Figure 2 shows a side view of the stepped fluidised bed concentrator 10 of Example 1 in normal operating position wherein the riffles 20,22 are in contact with the leading edges 24,26 of each of the stepped fluidising beds e.g. 14,16. Dry feed material (not shown) is fed at the top of the concentrator in the direction of arrow 38 so that fluidised layers 50 are formed on each of the fluidising beds. Oscillations of the diaphragm of the pump means shown by arrow 18 causes air to pulsate through the beds in the direction of arrows 51,52,53. The fluidising agitation of the layered material results in the separation of the coarse and fine concentrates wherein the fine concentrates can pass through the perforations in the beds as shown by sets of arrows 54,56 for collection via collection spigot 60 and the coarse concentrates are captured behind the riffles. Waste material (not shown) which has been stripped of the coarse and fine concentrates is discharged into a waste chute 40 at the end of the concentrator deck. Figure 3 shows a side view of the preferred concentrator 10 of Example 1 in the cleaning position. This view shows by operating the lever 34 in the direction of arrow 72 that the riffles 20,22 connected by connecting arm 32 (one side shown) can be raised clear of the fluidising beds 14,16. This arrangement enables the cleaning of the beds to remove the build up of the coarse concentrates captured behind the riffles which reports to coarse concentrate chute 41 at the end of the concentrator t.o* deck once the deck is pivoted on pivot bearing 80 towards a more vertical position as shown by arrow 82. Referring to Figure 4 there is shown an isometric perspective view and a side elevation view of a preferred scarifying apparatus for use with the fluidised bed concentrator of Example 1.

The scarifying apparatus is preferably comprised of longitudinal support members 93 which support scarifying rods 94 adapted to slide against or as near as possible to the perforated surfaces of the stepped beds. In operation, the scarifying apparatus is oscillated from side to side as shown by double-headed arrow 92 so that the rods sweep the length of the beds to scarify the dry materials on the beds. The disturbance of the dry material improves the passing of fineconcentrates through the 8 perforations in the beds for collection. In this view the motorised means for oscillating the scarifier is not shown although the scarifier can also be manually operated. Preferably the scarifier oscillates from side to side at a stroke rate of approximately 10 strokes per minute wherein each scarifier rod takes 4 seconds to cover a distance of 1 foot. The three longitudinal support members 93 are preferably 1 inch by 1 inch rectangular hollow section x 1' RHS) steel. The rods are preferably 3/8 inch diameter mild steel. It will be obvious that the number of longitudinal support members determine the distance each rod will cover, for example, three support members results in each rod covering only a third of the bed; four support members, a quarter of the bed, and so on.

The principle function of the scarifier is to keep the beds fluidised under all conditions thereby ensuring an even flow of fine concentrates through the perforations at all times. Preferably the scarifier can be raised clear of the fluidising beds for cleaning of the beds.

ADVANTAGES The principal advantages of the present invention include the fact that dry feed material is caused to remain on the fluidising beds for an extended period thereby improving the separation of coarse and fine concentrates from waste. The ability to disengage the riffling frame clear of the fluidising beds is also a major advantage in clearing and disposing of waste material at the end of the concentrator. As a result of its efficient dry separation process, operating costs are also lowered together with a reduction in the production of environmentally harmful dust and airborne particulate matter.

VARIATIONS

It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth.

Throughout the description and claims this specification the word "comprise" and variations of that word such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps.

DATED THIS 2 1 st DAY OF DECEMBER 2002 1) Clyde lan DOXFORD and Ross James THOMAS by their Patent Attorneys PIPERS BRISBANE

Claims

1. A stepped fluidised bed concentrator including in combination a concentrator deck comprising fluidising beds of perforated sheet material, the sheet material configured to form a plurality of stepped portions, each stepped portion forming a horizontal, elongate fluidising bed, fluidising means adapted to pulsate fluid through the perforations of the stepped portions, riffling means positional along leading edges of each fluidising bed, the riffling means adapted to riffle dry feed material into a fluidised layer on each bed, wherein in operation, dry feed material is caused by the riffling means to remain on the fluidising beds for an extended period thereby improving separation of coarse and fine concentrates from waste and wherein the fine concentrates can .1* pass through the perforations of each fluidising bed for collection and the coarse concentrates are captured behind the riffles while the waste discharges over the concentrator deck.

2. A stepped fluidised bed concentrator as claimed in claim 1, wherein the perforated sheet material is stainless steel with suitably sized apertures for screening intended fine concentrates.

3. A stepped fluidised bed concentrator as claimed in claim 2, wherein the intended fine concentrates are gold fines and the aperture diameter of the screen apertures are between 0.2mm and 1.0mm and optimally 0.4mm.

4. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein the surface profile of the concentrator deck is 11 planar however it can be convex or concave wherein the fluidising beds are always horizontal.

A stepped fluidised bed concentrator as claimed in any one of the above claims, wherein there are side plates on either side of the fluidising beds to prevent spillage of the fluidised layer at the sides or ends of each of the fluidising beds.

6. A stepped fluidised bed concentrator as claimed in any on of the above claims, wherein the riffling means is a ladder frame comprising a pair of arm members supporting therebetween a plurality of riffles of an angled or curved cross sectional configuration, the length and position of the riffles on the frame corresponding to the leading edges of the fluidising beds, wherein an angle or a curve of each riffle can be bought into contact with a corresponding leading edge to form a roofed or a coved ledge with the corresponding leading edge.

7. A stepped fluidised bed concentrator as claimed in claim 6, wherein the riffles are right angled.

8. A stepped fluidised bed concentrator as claimed in claim 6, wherein the riffles are not right angled but are of a different shape or cross sectional configuration.

9. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein waste discharges over the concentrator deck during normal operation.

10. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein the riffling means is disengageable with the fluidising beds to enable the cleaning of the beds including the build up of coarse concentrates behind the riffles. 12

11. A stepped fluidised bed concentrator as claimed in claim 10, wherein the disengagement of the riffling means from the fluidising beds is by way of hand operated lever and linkage means adapted to raise and lower the riffling means away from and onto the fluidising beds.

12 A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein there are mechanical, pneumatic or hydraulic means to raise and lower the riffling means away from and onto the fluidised beds.

13. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein there is a waste chute adapted to collect the waste at the end of the concentrator deck.

14. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein there is a coarse concentrate chute adapted to collect bed material and coarse concentrate discharge at the end of the concentrator deck.

A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein the fluidising means includes an oscillating diaphragm pump means located below and in sealed contact with the fluidising beds whereby fluid can be pulsated through the apertures or perforations of the fluidising beds.

16. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein the fluidising means is not an oscillating diaphragm pump means but another type of pump or means for pulsating the fluid. 13

17. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein the fluid being pulsated is air.

18. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein the pulsated fluid is fluid other than air.

19. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein the pulsated fluid is a liquid.

A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein there is a collection spigot adapted to collect fine concentrates passing through the fluidising beds at the base of the diaphragm of the oscillating diaphragm pump means.

21. A stepped fluidised bed concentrator as claimed in any one of the abovementioned claims, wherein there is a scarifying apparatus associated with fluidised bed concentrator, the scarifying apparatus adapted to oscillate from side to side to scarify the layer of dry feed material on each bed thereby improving the passing of fine concentrates through the apertures or perforations of the beds.

22. A stepped fluidised bed concentrator as claimed in claim 21, wherein the scarifying apparatus comprises one or more longitudinal support members supporting a plurality of scarifying rods adapted to slide against or as near as possible to the perforated surfaces of the beds.

23. A stepped fluidised bed concentrator as claimed in claim 21 or claim 22, wherein there is motorised means to oscillate the scarifying apparatus. 14

24. A stepped fluidised bed concentrator as claimed in any one of claims 21, 22 or 23, wherein the scarifying apparatus can be raised clear of the concentrator for cleaning purposes. A stepped fluidised bed concentrator substantially as herein described with reference to any one of the accompanying drawings. *I *i *t *lO