WO1995011094A1

WO1995011094A1 - Material sorter and separator

Info

Publication number: WO1995011094A1
Application number: PCT/AU1994/000637
Authority: WO
Inventors: John Borcuk
Original assignee: John Borcuk
Priority date: 1993-10-18
Filing date: 1994-10-18
Publication date: 1995-04-27

Abstract

A material sorter and separator comprising a frame supporting a motor which drives a textured belt. The frame includes an angled section which the textured surface passes over to form a sloping region. Material having a relatively lower coefficient of friction slides down the sloping region while material having a relatively greater coefficient of friction remains substantially stationary thereby resulting in a separation of the materials. The device is useful for separating talc from foreign material such as dolomite, tremolite or quartz.

Description

MATERIAL SORTER AND SEPARATOR

This invention relates to a device useful in the mining industry and in particular the talc mining industry. Disclosed is a method and means of separating a desired material (such as talc) from foreign material quarried during a mining operation. Material is separated due to differences in the coefficients of friction.

BACKGROUND ART

Talc (Mg₃Si₄O₁₀ (OH)₂) is mined by quarrying from bulk deposits. The quarrying operation generally results in an amount of foreign matter also being mined. The foreign material is commonly dolomite, tremolite, quartz and crystal. Typically the mining is a large scale open-cut operation and all mined material goes through a sizing and sorting process.

The talc mining is normally done by drilling and blasting or by using a large jack-hammer type machine known as a woodpecker. The removed material is loaded onto trucks and transported to an area where large pieces are broken up into sizes of fifty centimetres or less. The pieces are then sized by passing over a vibrating screen. A typical vibrating screen separates the talc pieces into sizes of up to 10 cm and over 10 cm up to 50 cm. At this stage of the sorting process there will be foreign matter, such as rocks of other mineral composition, mixed in with the talc. It is desirable to separate the foreign matter from the talc, which has hitherto not been feasible. The amount of foreign matter mixed with the talc determines the grading of the talc. For cosmetic use the talc must contain less than 1% acid soluble material, talc for cosmetic use is designated XL cosmetic. XL Industrial talc is not as pure as XL cosmetic talc and has up to 4% acid soluble material, it is used in a variety of industrial applications. Talc with a higher content of foreign matter is designated CC and is of limited use. The grade of the talc is reflected in its value, hence XL cosmetic talc can be sold at a much higher price than XL industrial or CC talc. Thus there is value in removing foreign matter so as to upgrade the talc.

To the knowledge of the inventor sorting of talc pieces to remove foreign matter has hitherto been done by hand. In one prior art method the talc and foreign matter is transported on a conveyor belt past a number of persons tasked with identifying and removing foreign matter from a constant stream of material. To assist in the task the material is wetted, typically with water, to assist in the identification of the foreign matter amongst the talc. Talc has a reasonably distinctive soft whitish grey appearance whereas most foreign matter mined with the talc has a darker colouring.

After sorting and separating, the talc is passed to a crusher where it is crushed to a fine or course powder depending on its ultimate use. Any foreign matter remaining with the talc after sorting and separation is crushed as well.

While the hand sorting method is relatively effective on large pieces of talc it is slow, expensive and unreliable on smaller pieces of talc less than 10 cm. A team of seven people working ten hour days can sort approximately eighty tonne of 10 cm XL talc in seven days. There is clearly a need for a method and means which can replace the hand sorting method with a faster, cheaper and more reliable technique.

OBJECT OF THE INVENTION

One object of the present invention is to provide a method and means for material sorting and separation which overcomes the above mentioned shortcomings in the existing hand sorting and separation method. It is a further object to provide a method and means of upgrading XL industrial and CC talc stocks to XL cosmetic.

It is a still further object of the present invention to offer the public a useful alternative to existing sorting and separation methods and means.

DISCLOSURE OF THE INVENTION In one form of the invention although it need not be the only or indeed the broadest form there is proposed a material sorter and separator comprising :

a frame supporting a drive means;

a textured surface driven by the drive means so as to move relative to the frame;

said textured surface being of a texture such that a first material having a relatively lower coefficient of friction moves relative to the textured surface and a second material having a relatively greater coefficient of friction remains substantially stationary relative to the textured surface;

such that the first and second materials are separated upon the textured surface.

The coefficient of friction between two surfaces is defined as the ratio of the force required to move one surface over the other to the total force pressing the two together. In cases where two different materials are in contact with a common surface the material having the relatively lower coefficient of friction will be easier to move. The inventor has discovered that this physical fact can be used to separate materials such as talc from other materials having a relatively greater coefficient of friction.

In preference the textured surface is a continuous belt and the drive means is a motor adapted to continuously drive the belt in a linear direction. The belt preferably has a sloping region such that relatively lower coefficient of friction material will slide down the sloping region while relatively greater coefficient of friction material does not slide.

Alternatively the textured surface is a disc and the drive means is a motor adapted to rotate the disc. The disk is preferably rotated at an angular velocity such that relatively lower coefficient of friction material slides to the outer edge of the disc under the influence of centrifugal action whereas relatively greater coefficient of friction material does not slide.

In a further form of the invention, although again not necessarily the broadest form, there is proposed a method of sorting and separating a material having a relatively lower coefficient of friction from a material having a relatively higher coefficient of friction including the steps of :

loading unsorted material onto a textured surface said textured surface being driven by a drive means;

driving the unsorted material upon the textured surface into a separation zone wherein material having a relatively lower coefficient of friction moves relative to the textured surface and material having a relatively greater coefficient of friction remains substantially stationary relative to the driven surface;

removing from the driven surface the moved material; and

collecting the moved material, substantially all of the collected material being material having a relatively lower coefficient of friction.

BRIEF DESCRIPTION OF THE DRAWINGS To further assist in understanding the invention reference will be made to the following drawings in which :

FIG 1 is a sketch of a talc separation machine;

FIG 2 is a plan view of the device of FIG 1;

FIG 3 is an enlarged view of a portion of FIG 1; FIG 4 shows a further embodiment incorporating roll restraining lines;

FIG 5 shows a third embodiment of a talc separating machine. DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in detail there is shown in FIG 1 a first embodiment of a talc sorting device, generally depicted as 1, comprising a frame 2 and textured belt 3. The textured belt 3 travels in direction of arrow 4 by virtue of belt drive wheel 5 and idle wheel 6. Material (including talc and foreign matter) to be sorted is delivered to the belt 3 from bin 7 and is carried in direction of arrow 4 by the belt 3.

Delivery to bin 7 may be in batches or a continuous feed arrangement may be used. Such material delivery systems would be known to persons skilled in the art.

Guides 8 direct the talc and foreign matter towards an outer edge 9 of the belt 3. The belt is twisted to form a sloping surface 10 (as shown most clearly in FIG 3) in the vicinity of an exit slide 11. The talc has a slippery surface and therefore slides down the sloping surface 10 and out the exit slide 11 to be collected. Foreign matter does not have such a slippery surface and therefore does not slip down the sloping surface 10.

The differentiation between foreign matter and talc is enhanced by providing a belt with a textured surface (as depicted particularly in FIG 3). The texture of the belt surface has a holding effect on the foreign matter but, due to its low coefficient of friction, the talc slides over the textured surface. The effectiveness of the separation of talc from foreign matter will depend on the texture and angle of the belt A smooth belt will permit both talc and foreign matter to slide out of the exit whereas a very textured belt could unduly restrain the talc. Similarly, a large angle will result in both foreign matter and talc sliding out the exit whereas a very low angle will result in no material sliding from the exit.

The inventor has found that a textured belt of a rubber material having a pattern of 3 mm deep by 1 mm wide groves running both laterally and longitudinally with approximately 2 mm spacings provides an appropriate textured surface. However, the inventor anticipates that other textured surfaces may be more appropriate with different size material or different types of foreign matter.

An angle of approximately 25 degrees has been found to be appropriate for the device shown in the figures. A higher angle is possible with a faster moving belt since the effectiveness of the separation process is related to the transit time of the talc across the sloped section of the belt relative to the transit time of the belt past the exit. The most effective speed and angle for a given material composition and belt type can be determined by simple experimentation. The inventor has found that a belt speed of approximately 0.5 m/sec is effective for the above mentioned belt and a slope of 25 degrees in sorting talc to at least XL industrial standard. Two or more talc separators can be operated in tandem to achieve better sorting.

In an alternative arrangement a talc separator can be constructed with two sloping regions. In such an arrangement a first low angle region will have a high sorting specificity but a relatively high proportion of talc will remain on the belt A second sloping region can be used to further separate talc from foreign material. Such an arrangement of two sloping regions can result in a higher talc recovery rate than a single sloping area arrangement. In a second embodiment a roll inhibiting means in the form of a number of flaps or lines are positioned over the sloping region of the belt of the first embodiment FIG 4 shows one arrangement in which nylon line 15 is used to inhibit rolling of the material. One end of the nylon line 15 is attached to a support bar 16 and the other end is attached to the frame adjacent the exit slide 11. The inventor has found that in the absence of the roll inhibiting means some foreign matter may roll from the belt and be collected with the talc. Providing flaps or lines over the sloping region inhibits the rolling of material. The talc can slide past the flaps or lines but foreign matter is restrained. Such an arrangement can further improve the separation efficiency of the device.

In a third embodiment, shown in FIG 5, the textured surface is in the form of a circularly rotating disc 17 rather than a linearly progressing belt. In the disc embodiment the talc moves to the outside of the disc 18 under the influence of centrifugal action whereas the restraining action provided by a textured surface of the belt counteracts the effect of centrifugal action on foreign matter. The foreign material is directed off the disk by a stop 19. As in the previous embodiments the material to be sorted is delivered from the bin 7. The inventor envisages that the belt arrangement of the first or second embodiments can be used in tandem with the disc arrangement of the third embodiment to produce XL cosmetic talc.

In a further optional feature of any of the embodiments described above the driven surface may be slightly agitated to promote the movement of the talc. One manner of producing the agitation is by passing the driven surface over undulating rollers.

The preferred embodiments described herein are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to the preferred embodiments may be evident to those skilled in the art and may be made without departing from the spirit and scope of the invention.

Claims

1. A material sorter and separator comprising :

a frame supporting a drive means;

2. The material sorter and separator of claim 1 wherein the frame includes an angled section and the textured surface passes over the angled section to form a sloping region such that the relatively lower coefficient of friction material slides down the sloping region while the relatively greater coefficient of friction material does not slide as much as the lower coefficient of friction material.

3. The material sorter and separator of claim 2 wherein the textured surface comprises a continuous belt and the drive means is a motor adapted to continuously drive the belt in a linear direction.

4. The material sorter and separator of claim 2 wherein the frame further comprises guide means adapted to guide material on the textured surface to an outer edge of the textured surface.

5. The material sorter and separator of claim 2 further comprising an exit slide associated with the sloping region such that material sliding down the sliding region will pass through the exit slide.

6. The material sorter and separator of claim 1 wherein the textured surface comprises a disc and the drive means is a motor adapted to rotate the disc at an angular velocity such that the relatively lower coefficient of friction material slides to an outer edge of the disc under the influence of centrifugal action whereas the relatively greater coefficient of friction material does not slide as much as the lower coefficient of friction material.

7. The material sorter and separator of claim 1 wherein the textured surface is formed from rubber material having a pattern of 3 mm deep by 1 mm wide groves running both laterally and longitudinally with approximately 2 mm spacings.

8. The material sorter and separator of claim 1 further comprising a material holding bin adapted to deliver material to the textured surface at a controlled rate.

9. The material sorter and separator of claim 1 further comprising textured surface agitation means adapted to agitate the textured surface to promote movement of the relatively lower coefficient of friction material.

10. The material sorter and separator of claim 1 further comprising roll inhibiting means adapted to inhibit rolling of material across the textured surface.

11. The material sorter and separator of claim 10 wherein the roll inhibiting means comprises a plurality of lines positioned above the textured surface.

12. The material sorter and separator of claim 1 wherein the frame includes two or more angled sections and the textured surface passes over the angled sections to form two or more sloping regions such that the relatively lower coefficient of friction material slides down the sloping regions while the relatively greater coefficient of friction material does not slide as much as the lower coefficient of friction material.

13. A material sorter and separator comprising :

two or more frames, each supporting a drive means;

two or more textured surfaces, one per frame, each driven by the drive means so as to move relative to the frame;

wherein each frame includes an angled section and each textured surface passes over a respective angled section to form a sloping region such that a relatively lower coefficient of friction material slides down the sloping region while a relatively greater coefficient of friction material does not slide as much as the lower coefficient of friction material;

said frames being arranged sequentially such that material sliding from a sloping region of one frame will fall onto the sloping region of a next frame.

14. A material sorter and separator for sorting and separating talc from foreign material comprising :

a frame supporting a drive means;

wherein the frame includes an angled section and the textured surface passes over the angled section to form a sloping region such that the talc slides down the sloping region while the foreign material does not slide as much as the talc;

the talc thereby being separated from the foreign material.

15. The material sorter and separator of claim 14 wherein the textured surface comprises a continuous belt and the drive means is a motor adapted to continuously drive the belt in a linear direction and wherein the belt is driven at a velocity of between 0.2 m/sec and 1 m/sec and the sloping region is at an angle of between 15 degrees and 40 degrees from horizontal

16. The material sorter and separator of claim 14 wherein the frame further comprises guide means adapted to guide the talc and foreign material to an outer edge of the textured surface.

17. The material sorter and separator of claim 14 further comprising an exit slide associated with the sloping region such that talc sliding down the sliding region will pass through the exit slide.

18. The material sorter and separator of claim 14 further comprising roll inhibiting means adapted to inhibit rolling of material across the textured surface wherein the roll inhibiting means comprises a plurality of lines positioned above the textured surface.

19. A method of sorting and separating a material having a relatively lower coefficient of friction from a material having a relatively higher coefficient of friction including the steps of :

removing from the driven surface the moved material; and