WO2023087078A1

WO2023087078A1 - Processes and apparatus for separating target material from particulate mixture

Info

Publication number: WO2023087078A1
Application number: PCT/AU2022/051397
Authority: WO
Inventors: Kevin Sullivan; Robert Mcintosh; Raymond John Feuerriegel
Original assignee: New Amigos Pty Ltd
Priority date: 2021-11-22
Filing date: 2022-11-22
Publication date: 2023-05-25

Abstract

A method and apparatus for separating a target particulate material from a mixture of particulate materials, such as ore. The process comprises placing the mixture on a bed of non-metallic ragging supported by a screen; and forcing gas through the screen and ragging bed to agitate the mixture and separate the target material from the rest of the mixture. The apparatus comprises: a screen; a structure configured to support the screen and a bed of ragging on top of the screen, the structure defining a chamber below the screen and a collection outlet at a bottom of the chamber; and a compressor configured to supply the chamber with pressurised gas to agitate particulate material placed on the ragging bed. The compressor is configured provide repeated pulses of pressure. The compressor is configured such that the frequency and magnitude of the pressure pulses can be selected by a user.

Description

"Processes and apparatus for separating target material from particulate mixture"

Cross-Reference to Related Applications

[0001] The present application claims priority from Australian Provisional Patent Application No 2021903766 entitled "Process for an Air Ore Sorter", filed on 22 November 2021, the contents of which are incorporated herein by reference in their entirety.

Technical Field

[0002] Embodiments relate to processes and apparatus for separating a target particulate material from a mixture of particulate materials, such as ore, for example.

Background

[0003] Most mining operations on alluvial or placer type deposits use "wet" gravity separation technology. That is, minerals are separated from lighter weight material by using a flow of water. Although wet plant technology can be profitable, it requires a large supply of water and also generates a large quantity of debris. Consequently, wet gravity separators cannot readily be used in dry areas. Furthermore, tailings dams are often required to be built to contain the environmentally hazardous slimes created by dirty water, adding to the cost of production. For environmental reasons, the use of large-scale wet separation plants is restricted or even prohibited in some countries.

[0004] To overcome such problems, ore sorters have been developed and used for waterless recovery of materials from dry deposits. Current known ore sorters use Xray, radiation detection, colour matching, photometric, chemical, smelting or magnetism to sort ore from waste material. Examples of Ore Sorters are patents 108273766, 109939960, 2017294, 113019985, 1205916, 103920648, 101436001, 20190390300, 204735337. These are methods are quite complex in nature and require significant monetary investment but are gaining popularity in the mining industry.

[0005] Current ore sorters or air blowers, using air for sorting are suited only to small scale batch operations on single targeted materials. Sorters using other methods are better suited to continuous or larger scale operations, but are usually of expensive and complex construction with a multitude of moving parts, and generally require vibrating mechanisms to achieve high volume throughput of deposit. Such concentrators are not easily transported and are usually required to be permanently sited on concrete pads.

[0006] Common design features of air sorters are that they are mainly of elongated configuration and volume is limited by maximum dimension. Perhaps the most significant disadvantage of most known air sorters is their poor processing rate and relatively low recovery rates. Most air sorters have single product usage and are labour, power and cost intensive.

[0007] It is desired to address or ameliorate one or more shortcomings or disadvantages with existing processes or apparatus for separating a target particulate material from a mixture of particulate materials, such as ore, for example, or to at least provide a useful alternative.

[0008] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0009] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Summary

[0010] Some embodiments relate to a process for separating a target particulate material from a mixture of particulate materials of different densities, the process comprising: placing the mixture on a bed of non-metallic ragging supported by a filtering screen; and forcing gas upwards through the screen and ragging bed to agitate the mixture and separate the target material from the rest of the mixture, with the target material on one side of the ragging bed and the rest of the mixture on the other side of the ragging bed. [0011] In some embodiments, a density of the ragging material is greater than a density of the target material. The process may further comprises removing the target material from above the ragging bed.

[0012] In some embodiments, a density of the ragging material is less than a density of the target material. The process may further comprises removing the target material from below the ragging bed. The process may further comprise collecting at least part of the target material from below the screen.

[0013] In some embodiments, the process may further comprise: removing the rest of the mixture from the ragging bed; removing the ragging from the screen; and collecting any remaining part of the target material which is too large to pass through the screen.

[0014] In some embodiments, the ragging is formed of a ceramic material.

[0015] In some embodiments, the gas is forced through the screen and ragging bed periodically in repeated pulses of pressure.

[0016] In some embodiments, at least part of the agitated mixture is allowed to settle onto or into the ragging bed due to gravity between the pulses of gas pressure.

[0017] In some embodiments, at least part of the agitated mixture is removed before it can settle onto the ragging bed.

[0018] In some embodiments, the process may further comprise applying additional treatment steps to the target material to remove different contaminants or separate other target materials.

[0019] Some embodiments relate to an apparatus for separating a target particulate material from a mixture of particulate materials of different densities, the apparatus comprising: a filtering screen defining a plurality of apertures of a size selected to allow passage of particles below a certain size; a structure configured to support the screen and configured to support a bed of loose ragging on top of the screen during operation of the apparatus, the structure defining a chamber below the screen and a collection outlet at a bottom of the chamber to allow processed material to be removed from the chamber; and a gas compressor configured to supply the chamber with pressurised gas, during operation of the apparatus, such that gas flows upwards through the screen to agitate particulate material placed on the ragging bed, wherein the compressor is configured to force gas through the screen and ragging bed periodically in repeated pulses of pressure, and wherein the compressor is configured such that the frequency and magnitude of the pressure pulses can be selected by a user and adjusted for different sorting processes.

[0020] In some embodiments, the apparatus may further comprise one or more baffles in the chamber configured to direct gas flow towards the screen.

[0021] In some embodiments, a position and orientation of the one or more baffles in the chamber is adjustable allowing the gas flow through the screen to be altered for different applications.

[0022] In some embodiments, the apparatus may further comprise one or more sweeper members connected to a sweeping mechanism which is configured to move the one or more sweeper members across the screen at a set height above the screen to spread the mixture of particulate materials over the ragging bed during operation.

[0023] In some embodiments, the structure further defines a channel at or near one or more edges of the screen, and the sweeping mechanism and sweeper members are configured to push some at least part of the mixture of particulate materials into the channel for collection. The speed of the sweeping mechanism may be adjustable.

[0024] In some embodiments, the sweeper members are flexible and configured to bend to pass oversized particles on the ragging bed.

[0025] In some embodiments, a height and angle of the sweeper members are adjustable relative to the screen. [0026] In some embodiments, the screen is removable and able to be replaced with different screens defining different aperture sizes.

[0027] In some embodiments, the screen comprises independent sub-screen panels, each able to be removed and replaced with different screens defining different aperture sizes.

[0028] In some embodiments, the structure further comprises dividing members between each of the sub-screen panels configured to separate the ragging bed into different regions configured to accommodate different ragging materials associated with corresponding subscreen panels.

[0029] In some embodiments, the structure defines a plurality of collection outlets, each associated with a corresponding one of the sub-screen panel.

[0030] In some embodiments, the structure defines a plurality of sub-chambers, each associated with a corresponding one of the sub-screen panels.

[0031] In some embodiments, the structure and screen are substantially round and the apparatus is configured to process particulate material conveyed to a centre of the apparatus and spread out radially over the screen towards an outer edge of the screen.

[0032] In some embodiments, the structure and screen are substantially rectangular and the apparatus is configured to process particulate material conveyed to one side of the apparatus and spread out linearly over the screen towards an opposite side of the screen.

[0033] In some embodiments, the apparatus may further comprise a dust cover to restrict dust from escaping the apparatus.

[0034] Some embodiments relate to a kit comprising: an apparatus according to any one of the described embodiments; and loose ragging material configured to form a ragging bed over the screen.

[0035] In some embodiments, the kit may further comprise a set of interchangeable screens with different aperture sizes and associated ragging materials of different diameters. [0036] In some embodiments, the kit may further comprise different ragging materials having different densities.

[0037] In some embodiments, the kit may further comprise one or more conveyors for moving material to or from the apparatus, and a vehicle to facilitate transport of the apparatus and one or more conveyors.

[0038] Some embodiments relate to a waterless pressurised air flow sorting process for the dry separation and sorting of materials in the 3-9 specific gravity range and for other materials such as gold and gemstones.

[0039] In some embodiments, process is based on the use of compressed air supplied by a fan, blower or compressor providing pressurised air flow into a single or series of chambers.

[0040] In some embodiments, the chambers have directional baffles to control the movement of air and are situated directly underneath a metal sizing screen which is then topped with a ceramic material to improve fluidisation of the beds.

[0041] In some embodiments, material is loaded onto the top of the sorter by means of conventional conveyor systems. Angular sweeper bars move material in an anti-clockwise direction across the face of the screening beds. This movement is enhanced by the pulses of air from below the beds.

[0042] In some embodiments, specific gravity combines with normal gravitational effects to cause heavier material to fall through the sorter beds and for waste product to be removed by means of a waste channel on the side of the sorter.

[0043] The sorter can be configured in most shapes and one embodiment of the sorter is in a circular configuration. This may allow for greater flow of material across a larger sorting surface area depending on the dimensions.

[0044] In some embodiments, the process is waterless and uses limited amounts of electricity. [0045] In some embodiments, the process can be used to sort multiple types and sizes of materials at the one time by using different size ceramic ragging material and different size screening beds.

[0046] Some embodiments relate to a process using airflow for the sorting of minerals contained in dry alluvial/eluvial mining and tailing deposits. Some embodiments are directed to an air sorter process for separating materials in the range of specific gravities of 3 to 9 and for other materials such as gold or gemstones from such deposits using specific gravity, movement, gravitational effect and airflow.

[0047] The process the ore sorter in this embodiment uses is a combination of gravity, air flow and sweeper agitation to fluidise stratified beds. Liberated dry material is conveyed onto the central start point of the process by conventional means at an appropriate speed. This material falls on to a bed consisting of variable size metal wire screens. These sizing screens allow for the collection of material to required sizes through the sizing screen to a collection point under the sorter and/or the collection of waste material on the outer edges of the screen. A series of sweeper bars made of mild steel moves material across the top of a sizing screen. On top of the screen sits a ceramic material which is used to rag the beds i.e., it is used to fill in the gaps in the sizing screen until the sorting process commences. The ceramic nature of the material prevents any cohesion due to moisture/rust action. The compressed airflow used to fluidise the beds is sourced from a fan/blower or compressor and is fed into a chamber of compressed air which releases the air in a sequence according to the shape of the sorter.

Square or rectangular sorters require air flow in the single direction along the bed in pulses whereas a round sorter requires sequential air flow in a round fashion. The chamber has baffles which are directionally adjustable to allow for controlled increases in air flow in particular sections of the sorter. This allows for control of airflow towards material ranging from coarser heavier style gravels to dusty light materials where loss of fines in material is a significant issue.

[0048] In some embodiments, material is moved along the beds by a sweeper bar which is angled to move material from the centre of the sorter to the outside edges of the sorter. In the square/rectangular shaped sorter, the sweeper bar is a continuous track style revolving along the top of the screens in a rotating fashion. The bars of the sweeper arm are offset to ensure the material being fed onto the beds is able to flow through the sweeper arm assembly. In the round shaped sorter, the arms rotate in a circular fashion and are offset to push material from the centre loading point to the outside of the beds. Direction of movement is anti-clockwise.

[0049] In some embodiments, collection of the targeted material through the sizing screen occurs due to the air generated fluidisation of the material. Waste material is collected through tunnels at either side of the rectangular/ square versions of the sorter. This waste product tunnel is angled downwards to ensure the free flow of material away from the sorter to conventional conveyor systems. In the round embodiment, an open topped tunnel surrounding the outside of the collects waste material and this is sloped towards ejections ports on the sides of the sorter. This then allows for the material to conveyed away using conventional methods.

[0050] Technical problems identified in the present application.

[0051] Most ore sorters use sophisticated electronic equipment to process a single material. Most are not able to be adapted to differing minerals. They have the added disadvantage of requiring tailings dams for the storage of waste which is toxic in nature from smelting and chemical sorting. A number of environmental incidents have occurred over a number of years from unexpected release of tailings dams into the general environment. Most sorters are highly technical requiring significant training in the operation of the sorter.

[0052] Most ore sorters use significant electrical power requiring generation on site which again leads to environmental issues. Most ore sorters are not able to remove contaminates as the target in ore materials rather than removing the targeted ore. For examples known ore sorters are not able to remove material which is a penalty material in ore at the same time as collecting the targeted ore.

[0053] Solution according to some embodiments.

[0054] In some embodiments, the process has the ability to target both the desired ore and a contaminant at the same time during the sorting process. This is achievable where there is a difference in specific gravity between both materials. Using air to fluidise the flow of material, allows for the different specific gravity of materials to operate on both the targeted and contaminated material, separating the heavy materials from the lighter materials. This process works on material in the 3-7 specific gravity range is also able to work on heavy material such as gold and precious and semi-precious gemstones.

[0055] In some embodiments, the process apparatus has low power requirements with a normal operating requirement for 20 tonnes/hr being 4kw/hr. This is significantly less than the normal operating requirements of most ore sorters.

[0056] Gravity forms part of the solution to the identified problems. Gravity is used to allow heavier materials to fall to the bottom of a stratified material bed. These heavier materials can consist of either the contaminate or the targeted material. Again, gravity is standard around the world and does not require any alteration for the operation of the invention.

[0057] In some embodiments, the process uses gravity and a sweeper arm movement to stratify material on a bed. Compressed air flow then fluidises the beds causing further separation of the materials. This compressed air is released in waves further causing movement of the material along the beds and sorts the targeted ore from the waste products. The sweeper arm then finishes the process by moving the remaining waste product off the sizing screen beds into a waste collection area.

[0058] In some embodiments, a ceramic material is on the beds of a heavier specific gravity than the targeted material to allow further movement within the beds. This ceramic material allows for little to no interlocking of the beds allowing the beds to move freely. This ceramic material acts as a filter to the material processing through the beds.

[0059] In some embodiments, the beds consist of a metal screen sized to the appropriate size for the material being processed. These wire screens are able to be sized appropriately for targeted materials such as particular size gemstones. The first screen may be a 5mm screen aimed at collecting gemstones of industrial rather than gem quality. The next screen in the direction of movement can be larger allowing for the sorting of the next size of gemstone such as 8mm. The following wire screen is able to be sized to a maximum size that is desired for collection. Any oversized gemstones will be captured on the beds and will not pass through the screens. This will revert to a batch style of operation requiring minimal disruption to operation as the majority of gemstones will fall through the screening process. [0060] In some embodiments, baffles under the metal screen allow for directional aiming of the air to improve agitation of the beds. Use of variable speed controllers on both the sweeper arm movement speed, air pressure capacity and air aperture openings allow for customised speeds and directional control of the air flow.

[0061] In some embodiments, the apparatus is compact in size and able to be used singly or in sequence allowing for greater throughput. Upscaling of the size of the sorter allows for increases of volumes through the sorter of up to 40 T/hr for one sorter. The process is only restricted by the feed capacity. For example, 80T/hr will require two ore sorters using this process, 120T/hr requires 3. The apparatus is able to be manufactured in different shapes from rectangular to square or round. This adaptability allows for the sorter to fit into a desired area and is not restricted to particular shapes.

[0062] In some embodiments, the sorter does not use any water which makes it ideal for use within any of the 17% of the arid land within the world. In some embodiments, the sorter is better sorted to the driest materials but may be able to operate with up to 4% moisture content in the targeted material.

[0063] Advantageous Effects according to some embodiments.

[0064] In some embodiments, the apparatus is fully transportable and has a low power requirement than current ore sorters. In some embodiments, the apparatus does not use water at any stage of the process. There are no pollution issues related to any of the sorting processes.

[0065] In some embodiments, the sorter is fully self-contained, requires limited training and is able to process ore at the nominated rate by slowing down/increasing the process through the use of variable speed controllers.

[0066] In some embodiments, the process is able to be configured for both batch and continuous flow and is able to be adapted to different materials by changing the specific gravity of either the ceramic material on the screen beds or by alteration of the air flow characteristics and sweeper bar speeds of the sorter. [0067] In some embodiments, material is able to screened to size requirements. This is particularly important with the collection of gemstones. The ability to screen differing size material in sequence or order is a characteristic not shared by other conventional sorters.

[0068] In some embodiments, the limited number of working parts on the sorter and its construction in mild steel contribute to very small amounts of wear and tear and a significant reduction in the maintenance costs of sorters.

[0069] In some embodiments, the process allows for combinations of screen size, air pressure and ceramic material to be utilised to collect and sort different materials in the one pass through the sorter. For example, the first screen could be smaller in size with a higher specific gravity and used for the collection of gold. The second screen in line could have a larger screen with lower specific gravity to capture other precious materials such as silver. With the specific gravity of gold being 19 and silver being 10, this process allows for the sorting and collection of both materials in the one pass. Most other sorters are mineral specific.

[0070] The process is applicable in most forms of mining whereby a target material is of a specific gravity which differs from the specific gravity of the surrounding waste product.

[0071] In some embodiments, the process allows for both the collection of a targeted material or the collection of a liability product and then the collection of a targeted material through the waste channels rather than through the screens. This process gives flexibility to the sorting process in mining and has significant upgrade ratio achievability.

[0072] This process is not mineral specific nor is it size specific. In some embodiments, the process will work with any liberated material within the 3 - 9 specific gravity range and will work equally well with the heavier materials such as tin/tantalite and gold.

[0073] In some embodiments, the process allows for a sizing component to be brought into the sorting of minerals. This sizing is particularly important in terms of gemstones but also allows for the significant cost reduction where a targeted mineral is no bigger than a certain size. Screening off of material that is larger than that can generate significant economic savings by reduction of secondary processing volumes. For example, the upgrade ability of this process is regularly recorded in the several hundred to one area. For every 100 metres of material passing the sorter only one metre of sorted material will require further processing, greatly reducing the processing costs associated with this reprocessing.

[0074] Some embodiments relate to a waterless process using air for the sorting of materials contained in dry alluvial/eluvial mining and tailing deposits. In particular, the process is directed to an air sorting and separation of materials in the range of specific gravities of 3 - 9 and for other heavier materials such as gold or gemstones from such deposits using specific gravity, movement, gravitational effect and airflow.

[0075] In some embodiments, the process uses compressed air flowing to a chamber where it is directed by directional baffles into adjustable screening beds. The beds are lined with ceramic material. Air flow fluidises material passing across the bed with the assistance of a sweeper arm. Material of a targeted material/s fall through the beds for collection and waste material is removed by a sweeper arm. Contaminates can also be removed from material using the same process.

Brief Description of Drawings

[0076] Embodiments will now be described, for exemplary purposes only, with reference to the drawings, in which:

[0077] Figure 1A is a cross-section of a filter screen, according to some embodiments;

[0078] Figure IB is a cross-section of the screen of Figure 1A supporting a bet of ragging;

[0079] Figure 1C is a cross-section of the screen of Figure 1 A and ragging of Figure IB supporting a bed of material to be processed;

[0080] Figure ID illustrates air flow through the screen and ragging to agitate the material;

[0081] Figure IE illustrates the stratification and settling of the material and ragging onto and through the screen; [0082] Figure 2A is a cross-section of a generalised apparatus for separating a target material from a mixture of particulate materials using air agitation;

[0083] Figure 2B shows the apparatus of Figure 2A with a bed of ragging and material to be processed on top of the screen;

[0084] Figure 3 is a cross-section of an alternative embodiments of the apparatus;

[0085] Figure 4A is a cross-section of an alternative embodiments of the apparatus;

[0086] Figure 4B is a plan view of the apparatus of Figure 4A;

[0087] Figure 5 is a schematic view of a kit of equipment including conveyors and dust cover, according to some embodiments;

[0088] Figure 6A is a perspective view of an apparatus for separating a target material from a mixture of particulate materials, according to some embodiments;

[0089] Figure 6B is a partial perspective cross-section assembly view of the apparatus of Figure 6A;

[0090] Figure 6C is a cross-section view of the assembled apparatus of Figure 6A;

[0091] Figure 6D is a partial perspective cross-section showing a lower stationary structure of the apparatus of Figure 6A;

[0092] Figure 6E is another partial perspective cross-section showing a lower stationary structure of the apparatus of Figure 6A;

[0093] Figure 6F is a perspective view of a sweeper mechanism of the apparatus of Figure 6A;

[0094] Figure 7 illustrates an alternative embodiment of the apparatus, wherein Standard conveyor system (1) conveys material (2) on top of the sorter. Sweeper bars (11) turn in an anticlockwise direction driving material from centre to outside of the sorter where it falls into the waste tunnel (4) and falls out of the sorter through channel (5). Compressed air from a fan, blower or compressor (7) is forced into the sorter via piping (6).

[0095] Figure 8 illustrates further details of the apparatus of claim 7 according to some embodiments. Air flow is then forced up into the body of the sorter through a series of directional baffles (8) contained within individual chambers (9). Air is then forced up through a sizing screen (10) sitting above the chamber which has angular sweeper bars (11) for moving the material across the face of the beds. These chambers are topped with variable size metal screens (Figure One 15). Collection of the targeted material is through the individual chambers into their respective collection points (based on any sloping wall design) (Figure One 13) and extracted through a spigot arrangement (Figure One 14).

Description of Embodiments

[0096] Embodiments relate to processes and apparatus for separating a target particulate material from a mixture of particulate materials. The described embodiments may be adapted to various applications, such as in chemical processing, food processing or agriculture, for example, and particularly in processing ore and minerals.

[0097] In order to illustrate the physical mechanisms which are utilised in the processes and apparatus of the described embodiments, a generalised particle separation process is described below in relation to Figures 1A to IE. Further optional features of various processes and apparatus are then described according to various embodiments.

[0098] Figure 1A shows a cross-section of a screen 100. The screen 100 may comprise any suitable filtering screen which allows particles below a certain size through while restricting passage of larger particles of material. For example, many different screens or gratings are commonly used in ore processing for sizing ore to different grades.

[0099] The screen 100 may comprise a mesh, or grill, or any suitable screen defining apertures of a certain size and/or shape to allow particles of a certain size through.

[0100] Figure IB shows the screen 100 supporting a bed of ragging material, also known as a ragging bed, or simply “ragging” 105. Ragging is loose material, typically of a certain size or size range and known density. The ragging particles may be round or spherical, for example, but could also be other shapes in different embodiments.

[0101] The ragging 105 sits on top of the screen 100, but does not pass through as it is too large to pass through the screen 100. For example, the ragging 105 may be in the range of 1mm to 2mm larger than the size threshold for particles to pass through the screen.

[0102] Figure 1C shows a mixture of particulate material 110 on top of the ragging 105. The mixture 110 may comprise a range of different particle sizes, materials and densities. For example, the mixture 110 may comprise a mined ore containing one or more target materials, such as minerals or gemstones, as well as a (typically large) proportion of unwanted waste material or contaminants.

[0103] Depending on the size of the ragging 105 and screen 100, the ragging 105 may block the screen and restrict the mixture 110 from passing through at rest. However, when sufficiently agitated, part of the mixture 110 with a higher density will gradually fall down into and below the ragging 105, and (if small enough) through the screen 100. The remainder of the mixture 110, which is lower density than the ragging 105, will stay above the ragging 105.

[0104] The ragging 105 and mixture 110 to be sorted may be agitated by vibration, or by passing water through it. However, as discussed, there are various difficulties with these approaches, and the current embodiments are directed to using air flow to agitate the ragging 105 and mixture 110. Other gases could also be used instead of air, which may be beneficial in some applications. In relatively remote mining locations, it may be preferable to use air as the working fluid, since it is readily available and doesn’t need to be sourced.

[0105] Figure ID illustrates air flow up through the screen 100 and ragging 105, as indicated by the arrows, to agitate the ragging 105 and mixture 110. This air flow agitation is strong enough to lift the ragging 105 off the screen 100 enough to unblock the screen 100. The air flow also fluidises the ragging bed 105 and mixture 110. This allows the mixture 110 and ragging 105 to stratify into different layers according to the relative densities of the materials in the mixture 110 and the ragging 105. [0106] In Figure IE, the air flow is reduced so that the ragging 105 and mixture 110 is allowed to settle back down onto the screen 100.

[0107] A first component of the mixture 110a which is more dense than the ragging 105 and small enough to pass through the screen 100 is shown falling down below the screen. For example, this might be gold fines, recovered from a mix of ore.

[0108] A second component of the mixture 110b which is less dense than the ragging 105 and is shown sitting above the ragging 105. For example, this might be waste material to be discarded, or it may have other valuable components to be removed in further processing.

[0109] A third component of the mixture 110c which is more dense than the ragging 105 but too large to pass through the screen 100 may be left sitting between the ragging 105 and the screen. For example, larger gold nuggets, which may be collected after removing the ragging 105.

[0110] This process may be done in several repeated steps, for example by repeatedly forcing air through in pulses to agitate the ragging 105 and mixture 110 and allow partial stratification with each pulse to gradually stratify the mixture further and separate the various components as set out above.

[0111] As discussed previously, separating ore components using a ragging bed a screen has conventionally only been done with water, which has various disadvantages. There is an earlier example of using air flow to agitate ragging, in PCT application WO 9009246 Al. However, it is has only been used for targeting gold using a particular set up to suit that purpose.

[0112] The embodiments described herein can be adapted to targeting many different materials of different densities by adjusting various process parameters or apparatus features.

[0113] Some embodiments relate to a process for separating a target particulate material from a mixture of particulate materials of different densities, the process comprising: placing the mixture on a bed of non-metallic ragging supported by a filtering screen; and forcing gas (e.g., air) upwards through the screen and ragging bed to agitate the mixture and separate the target material from the rest of the mixture, with the target material on one side of the ragging bed and the rest of the mixture on the other side of the ragging bed.

[0114] Conventional ragging comprises ferrous materials, such as steel beads. It has been found that conventional ragging can sometimes get stuck together or locked in place due to oxidation and/or dirt build up. It can be time consuming to loosen and clean ragging in this situation.

[0115] This issue can be reduced by using non-metallic ragging. Non-metallic ragging does not oxidise, so there is less likelihood of the ragging sticking to itself and the fine dust particles of the materials being processed.

[0116] Any suitable ragging material may be used, including ceramic materials, for example, in any suitable shape and size. For example, the particles of ragging material may be smooth, round or spherical. Some suitable ragging materials include grinding beads which are conventionally used in the mining processing industry for grinding other materials into smaller particle sizes. For example, King’s Beads manufactures substantially spherical ceramic beads in a range of different material compositions with different densities shown as specific gravity (SG) relative to water, including:

[0117] In some embodiments, metallic ragging may be used, for example, if oxidisation and rag locking is less of a concern.

[0118] The ragging material may be selected depending on the densities of the materials in the material mixture being processed and the target material to be separated from the rest of the mixture. [0119] In some embodiments, a density of the ragging material is less than a density of the target material. In this case, the component 110a (and in some cases component 110c) of the mixture which settles below the ragging 105 is the target material.

[0120] The process may further comprise removing the target material from below the ragging bed 105. That is, both components 110a and 110c will eventually settle below the ragging bed 105, whether they pass through the screen 100 (component 110a) or not (component 110c). These components can then be collected.

[0121] The process may further comprise collecting at least part of the target material (110a) from below the screen 100. That is, whichever material 110a passes through the screen 100.

[0122] In some embodiments, the process may further comprise: removing the rest of the mixture 110b from the ragging bed 105; removing the ragging 105 from the screen 100; and collecting any remaining part of the target material 110c which is too large to pass through the screen 100.

[0123] The remaining mixture component 110b sitting above the ragging bed 105 may be considered waste material, in some cases. In other cases, component 110b may comprise additional target materials of value and be separated from the contaminants in further processing steps.

[0124] For example, the process may be repeated with a different ragging material 105 having a lower density to separate the further target material from the unwanted components of the mixture 110.

[0125] In this way, the process may be repeated many times using ragging materials of different densities to separate different target materials from the mixture 110.

[0126] In some embodiments, a density of the ragging material is greater than a density of the target material. In this case, the component 110b of the mixture 110 which settles above the ragging bed 105 is the target material, and the remaining components 110a, 110c settle below the ragging 105. [0127] The process may further comprises removing the target material (110b) from above the ragging bed. For example, this can be done by sweeping the target material 110b off the top of the ragging bed 105 into a collection receptacle.

[0128] The remaining mixture components sitting below the ragging bed 105 (component 110c) and passed through the screen 100 (component 110a) may be considered waste material, in some cases. In other cases, components 110a, 110c may comprise additional target materials of value and be separated from the contaminants in further processing steps.

[0129] For example, the process may be repeated with a different ragging material 105 having a higher density to separate the further target material from the unwanted components of the mixture 110.

[0130] In some cases, whether the target material has a higher or lower density than the ragging 105, the target material may itself comprise a mixture of materials. For example, the target material may comprise multiple different target minerals and/or gemstones, and may also include unwanted contaminants which may be removed with further processing steps.

[0131] For example, the further processing steps may include repeating the process with a different ragging material with a different density, or may include conventional mineral processing methods, such as magnetic separation, electrostatic separation, froth flotation, chemical processing or acid leeching.

[0132] Using conventional methods on large quantities of ore with small concentrations of target material is very expensive due to transport costs as well as the costs associated with the processing itself. The described embodiments of the present disclosure can be used to remove some (if not all) of the contaminants at a much lower cost, and reduce the cost of any further processing steps which may be required.

[0133] In particular, the described embodiments using air (or gas) agitation require significantly less energy than conventional mineral processing; do not require water or chemical products; and can be achieved with relatively inexpensive equipment.

[0134] In some embodiments, the gas (e.g., air) is forced through the screen and ragging bed periodically in repeated pulses of pressure. The magnitude and frequency of the pressure pulses may be selected to suit certain applications. For example, if the pressure pulse is too high or too long in duration, some of the target material may be dispersed and lost. However, the pressure pulse should generally be high enough to lift the ragging 105 and material mixture 110 or agitate it sufficiently to allow stratification, as described above.

[0135] In general, the pressure and air flow may be adjusted so that the bulk of the material is lifted above the screen by a level in the range of 50mm to 300mm, 100mm, to 200mm, or about 150mm, for example.

[0136] The pressure and air flow rate required to do this will also vary depending on the materials, conditions, and specifications of the apparatus. For example, the average chamber pressure may be in the range of lOPa to lOOOPa, 50Pa to 500Pa, or 60Pa to lOOPa above ambient atmospheric pressure. The magnitude of the pressure pulse may be greater than the average pressure by a factor of at least, 3, 4, 5, 6, 8, 10, 20 or 30, for example.

[0137] At the peak of the pressure pulse, the air flow velocity through the screen 100 may be in the range of Im/s to 20m/s, 5m/s to 15m/s, 8m/s to 12m/s, or about lOm/s, for example.

[0138] The frequency of the pressure pulses may be in the range of 1Hz to 10Hz, 2Hz to 8Hz, 3Hz to 6Hz, 4Hz to 5Hz, or about 4.5Hz.

[0139] The duration of the pressure pulse may be a fraction of the period between pressure pulses, the fraction being in the range of 5% to 25%, 6% to 20%, 8% to 16%, 10% to 14%, or about 12%, about 12.5%, about 6%, or less than 25%, less than 20%, or less than 15%, for example. The duration of the pressure pulse may be in the range of 10ms to 100ms, 15ms to 50ms, or 20ms to 30ms, for example.

[0140] In some embodiments, at least part of the agitated mixture is allowed to settle onto or into the ragging bed due to gravity between the pulses of gas pressure. Allowing this settling time may reduce the likelihood of the material being inadvertently dispersed and lost.

[0141] In some embodiments, at least part of the agitated mixture is removed before it can settle onto the ragging bed. Once stratified, the component 110b of the material above the ragging bed 105 can be removed, for example by sweeping it to one or more sides of the screen 100. In a fluidised state, the material can be moved with less resistance. Therefore, it may be beneficial to sweep part of the material 110b away while it is in a fluidised state due to the gas agitation before entirely settling onto the ragging bed 105.

[0142] Referring to Figures 2A and 2B, a simplified cross-section of an apparatus 200 is shown, according to some embodiments, which may be used to carry out the process described above. The various embodiments of the apparatus 200 may be arranged to be rectangular or annular, as discussed further below. Therefore, a cross-section is shown in Figures 2A and 2B to illustrate the general principles and various optional features of the apparatus 200.

[0143] Figures 2A and 2B illustrate an apparatus 200 for separating a target particulate material from a mixture 110 of particulate materials of different densities. The apparatus 200 comprises a filtering screen 100 defining a plurality of apertures 101 of a size selected to allow passage of particles below a certain size.

[0144] The apparatus 200 comprises a structure 201 configured to support the screen 100 and configured to support a bed of loose ragging 105 on top of the screen 100 during operation of the apparatus 200. The structure defines a chamber 220 below the screen 100 and a collection outlet 225 at a bottom of the chamber 220 to allow processed material to be removed from the chamber 220.

[0145] The apparatus 200 also comprises a gas compressor 230 configured to supply the chamber 220 with pressurised gas (e.g., air), during operation of the apparatus 200, such that gas flows upwards through the screen 100 to agitate particulate material 110 placed on the ragging bed 105. The compressor 230 is configured to force gas through the screen 100 and ragging bed 105 periodically in repeated pulses of pressure, and the compressor 230 is configured such that the frequency and magnitude of the pressure pulses can be selected by a user and adjusted for different sorting processes.

[0146] The following discussion will refer to air flow, but it will be understood that any suitable gas may be used for a given application. Also, the term “compressor” is intended to include any suitable fan, blower or air compressor, including axial, displacement, centrifugal and screw fans/blowers/compressors, and any other apparatus for increasing the pressure in the chamber 220 to cause gas flow through the screen 100. [0147] The compressor 230 may also comprise pressure regulating equipment and a controller to allow control of the pressure in the chamber 220. For example, this may include the magnitude, frequency and/or duration of the pressure pulses.

[0148] The compressor 230 is shown on one side of the chamber 220, but may be arranged differently in other embodiments. For example, the apparatus 200 may comprise a plenum, or ducting or pressure manifolds configured to deliver pressurised air from the compressor 230 to the chamber 220.

[0149] In some embodiments, the apparatus 200 may further comprise one or more baffles 235 in the chamber 220 configured to direct air flow towards the screen 100. The baffles 235 are shown in cross-section in Figures 2A and 2B, and may extend across different regions of the chamber 220 to achieve the desired air flow for a given application.

[0150] The baffles 235 may define surfaces arranged to redirect air flow from the compressor 230 to the screen 100, as illustrated by the solid arrows in Figures 2A and 2B. In some embodiments, baffles 235 may not be required at all.

[0151] The baffles 235 may be flat/straight or curved in cross-section, as shown in Figures 2A and 2B. The baffles 235 may be positioned and oriented in the chamber 220 to direct air flow as desired. For example, the baffle 235 on the left of Figure 2A is shown positioned at an angle to the flow from the compressor 230 which may be varied in different embodiments, but it could also be arranged vertically (as shown in Figure 3) depending on the flow requirements. The baffles 235 are shown positioned at a stand-off below the screen 100, which may be varied in different embodiments, or in some embodiments, the baffles 235 may be positioned to abut the screen 100.

[0152] In some embodiments, a position and orientation of the one or more baffles 235 in the chamber 220 may be adjustable allowing the gas flow through the screen 100 to be altered for different applications. For example, the baffles 235 could be hinged, or simply configured to be removed and replaced in different positions and orientations as desired.

[0153] The collection outlet 225 is positioned at the bottom of the chamber 220 to allow processed material to be removed from the chamber 220. The chamber 220 may be partially defined by sloped walls which slope down towards the collection outlet 225 so that material falling through the chamber 220 hits the sloped walls and is directed to the collection outlet. For example, the bottom of the chamber 220 may define a hopper.

[0154] The collection outlet 225 may comprise an opening or spigot in the bottom of the chamber 220, below which a collection container or conveyor may be positioned to carry the collected material away. In some embodiments, the collection outlet 225 may include a closure to selectively close the outlet 225 and open the outlet 225 periodically for the collection of the material.

[0155] In some embodiments, the apparatus 200 may further comprise one or more sweeper members 242 connected to a sweeping mechanism 240 which is configured to move the one or more sweeper members 242 across the screen 100 at a set height above the screen 100 to spread the mixture 110 of particulate materials over the ragging bed 105 during operation, as shown in Figure 2B, for example.

[0156] In some embodiments, the sweeping mechanism 240 may not be required, and alternative means for removing material from the ragging 105 may be employed.

[0157] The sweeping mechanism 240 is connected to the structure 201 and configured to move the sweeper members 242 relative to the screen 100 to move part of the mixture 110 over the screen 100 and ragging 105 in the direction shown in Figures 2 A and 2B.

[0158] The sweeping mechanism 240 may comprise any suitable mechanism, such as a chain link track or conveyor belt type mechanism, for example. Another sweeping mechanism 240 for an annular apparatus is described further below, according to some embodiments.

[0159] The structure may further define a channel 250 at or near one or more edges of the screen 100. The sweeping mechanism 240 and sweeper members 242 may be configured to push some at least part of the mixture 110 of particulate materials into the channel 250 for collection. The channel 250 may also define a channel outlet 255 to allow for collection of the material passing through the channel 250, similar to the collection outlet 225 in the bottom of the chamber 220. [0160] The speed of the sweeping mechanism 240 may be adjustable. Different material mixtures 110 may require different processing times, that is, the time or number of pressure pulses required to stratify and separate the target material from the rest of the mixture 110. The speed of the sweeping mechanism 240 may be adjusted to change the rate at which the material mixture is progressed laterally along the screen 100 to allow time to separate the materials, or increased to increase the material processing rate when that is prioritised.

[0161] The sweeper members 242 may be relatively flexible and configured to bend to pass oversized particles on the ragging bed 105. For example, the sweeper members 242 may comprise elongate steel bars configured to flex rather than rigidly impact oversized particles. In other embodiments, the sweeper members 242 may comprise brushes or wiper blades formed of more resiliently flexible materials, such as polymers, elastomers or rubber, for example, or metals such as steel cables or chains, for example.

[0162] A height and angle of the sweeper members 242 may be adjustable relative to the screen 100. This may allow the thickness of material on the ragging bed 105 to be adjusted to suit different sorting processes, or to change the way material is moved over the screen 100.

[0163] The structure 201 may also define a material input region 210 where the material mixture 110 can be fed into the apparatus 200. The material input region 210 shown in Figures 2A and 2B is a ramp at one end of the screen 100 sloping down so that material deposited on the ramp 210 falls down onto the screen 100. In other embodiments, the material input region 210 may comprise different structures configured to receive the input material and move it onto the screen 100. For example, as described in relation to Figure 6 below.

[0164] In some embodiments, the screen 100 is removable and able to be replaced with different screens defining different aperture sizes. This allows for the input material to be sorted based on size as well as density. For example, the material may be processed multiple times using different screen sizes and complimentary ragging sizes to gradually separate different sized particles of target material.

[0165] In some embodiments, the screen 100 comprises independent sub-screen panels 103, each able to be removed and replaced with different screens defining different aperture sizes. [0166] In some embodiments, the structure further comprises dividing members or barriers 104 between each of the sub-screen panels 103 configured to separate the ragging bed 105 into different regions configured to accommodate different ragging materials associated with corresponding sub-screen panels 103.

[0167] For example, Figure 3 shows a similar apparatus 300 suitable for separating different target materials from a mixture of materials in a single pass over the screen 100. All of the features are similar to apparatus 200, other than the bottom of the chamber 220 where the structure 201 defines a plurality of collection outlets 225, each associated with a corresponding sub-screen panel 103. Each collection outlet 225 is positioned below a corresponding sub-screen panel 103 with the bottom of the chamber 220 defined by sloping walls arranged to direct separated material falling from each respective sub-screen 103 towards the corresponding collection outlet 225.

[0168] This arrangement allows for different screen sizes and/or ragging materials 105 to be used for each sub-screen 103 to target different materials, which are then separated at the different sub- screens 103 and can be collected separately at the corresponding collection outlets 225.

[0169] For example, progressively less dense ragging could be used at each successive subscreen 103 so that the most dense target material can be separated at the first sub-screen 103, then the next sub- screen 103 and associated ragging 105 can separate a second target material which is less dense than the first ragging material and more dense than the second ragging material, and so on. This arrangement can allow multiple different target materials to be separated from a mixture in a single pass through the apparatus.

[0170] Figure 4A shows a similar apparatus 400 with a structure 201 that defines a plurality of sub-chambers 222, each associated with a corresponding one of the sub-screen panels 103. This arrangement ensures separation between different materials being separated at the different sub- screen panels 103 by providing internal walls between the sub-chambers 222.

[0171] In this embodiment, the sub-chambers 222 are not in direct fluid communication.

Therefore, a plenum 232 is provided in fluid communication with the compressor 230 and in fluid communication with each sub-chamber 222 via corresponding inlet apertures 233. The plenum 232 is shown extending alongside the sub-chambers 222 in Figures 4A and 4B.

[0172] In some embodiments the inlet apertures 233 may be selectively closed to control air flow to the corresponding sub-chamber 222. For example, to control the pressure pulse magnitude, frequency, duration, or timing, relative to the other sub-chambers 222. In some embodiments, the inlet apertures 233 may be opened alternatingly to successively deliver pressure pulses to each sub-chamber 222 in turn.

[0173] As mentioned previously, the apparatus may be configured to be rectangular or annular. Referring to Figures 4A and 4B, a rectangular arrangement is illustrated, for example.

[0174] The structure 201 and screen 100 are substantially rectangular and the apparatus is configured to process particulate material conveyed to one side 411 of the apparatus 400 and spread out linearly over the screen 100 towards an opposite side 412 of the screen 100.

[0175] In Figure 4B the sweeper mechanism 240 is omitted for clarity, and the sweeper members 242 are shown positioned just above the screen 100. The sweeper members 242 are shown extending laterally across the screen 100 at an angle relative to the direction of motion. In other embodiments, the sweeper members 242 may be arranged perpendicular to the direction of motion.

[0176] With the angled sweeper members 242, the material left on top of the ragging bed 105 will gradually be swept along the screen 100 in the direction of motion of the sweeper members 242, and also, partially, in a lateral direction towards a side 414 of the screen 100.

[0177] The channel 250 may extend along the end 412 of the screen as well as the side 414 of the screen 100 to catch material pushed off the screen 100 and ragging 105 by the sweeper members 240. The material collected in the channel 250 may then be moved to the channel outlet 255 (for example by gravity, vibration, or additional sweeper members) and collected separately. [0178] In some embodiments, the apparatus may further comprise a dust cover to restrict dust from escaping the apparatus. Referring to Figure 5, a simplified schematic of a dust cover 500 is shown according to some embodiments.

[0179] In the simplest form, the dust cover may cover the entire apparatus with a single access port for introducing and removing material. The dust cover may comprise a permanent or temporary structure. To facilitate portability of the apparatus, the dust cover may comprise a rigid frame supporting a flexible barrier membrane, such as a fabric, cloth or plastic sheet, for example.

[0180] In some embodiments, the dust cover 500 may define any one of the following apertures: material input aperture 510, air inlet 530 to supply the compressor 230 with fresh air, material collection apertures 525 associated with one or more of the collection outlets 225 or channel outlet 255, and an air outlet 535, which may have an associated dust filter 550, depending on the requirements of a given application.

[0181] Figure 5 also shows conveyors 590 configured to remove collected materials from the apparatus, which may include target materials or waste materials to be conveyed to collection bins or dump piles.

[0182] In some embodiments, the apparatus may be configured to be portable or mobile. For example, the apparatus may be sized to fit on a trailer to be carried to a work site.

[0183] Some embodiments relate to a kit comprising: an apparatus according to any one of the described embodiments; and loose ragging material configured to form a ragging bed over the screen.

[0184] For example, the kit may comprise different ragging materials having different densities, allowing different materials to be targeted. The ragging materials may comprise any suitable densities selected to target different materials. The specific gravity of the ragging material may be in the range of 2 to 20, 2.5 to 15, or 3 to 9, for example.

[0185] The kit may further comprise a set of interchangeable screens with different aperture sizes and associated ragging materials of different diameters. The ragging size associated with each screen size may be at least 0.5mm larger, at least 1mm larger, or at least 2mm larger, for example. The ragging size or average diameter of ragging particles may be in the range of 2mm to 20mm, 3mm to 15mm, 4mm to 10mm or 5mm to 8mm, for example, or about 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, or 12mm, for example.

[0186] In some embodiments, the kit may further comprise one or more conveyors 590 for moving material to or from the apparatus. The kit may also include a vehicle to facilitate transport of the apparatus and one or more conveyors. For example, the vehicle may comprise a trailer configured to be towed by a truck.

[0187] In some embodiments, the apparatus is configured in an annular arrangement, the structure and screen are substantially round and the apparatus is configured to process particulate material conveyed to a centre of the apparatus and spread out radially over the screen towards an outer edge of the screen.

[0188] Referring to Figures 6A to 6F, an annular apparatus 600 is described, according to some embodiments. The apparatus 600 may include any of the features described in relation to other embodiments, and similar features are indicated with like reference numerals. The apparatus 600 may comprise any suitable size and proportions for a given application. The apparatus 600 shown in the drawings is approximately 2.7m in diameter and 2.5m tall.

[0189] The apparatus 600 comprises a filtering screen 100 defining a plurality of apertures of a size selected to allow passage of particles below a certain size. The screen 100 comprises three annular sub-screens 103 arranged concentrically and separated by dividers 104, as shown in Figures 6B, 6D and 6E.

[0190] The apparatus 600 comprises a structure 201 configured to support the screen 100 and configured to support a bed of loose ragging 105 on top of the screen 100 during operation of the apparatus 600.

[0191] The structure 201 defines a plurality of sub-chambers 222 below the screen 100 and a collection outlet 225 at a bottom of each sub-chamber 22 to allow processed material to be removed, as shown in Figures 6A to 6E.

[0192] The apparatus 600 also comprises a gas compressor 230 configured to supply the chamber 220 with pressurised air, during operation of the apparatus 600, such that air flows upwards through the screen 100 to agitate particulate material 110 placed on the ragging bed 105.

[0193] The apparatus further comprises a sweeper mechanism 240 configured to rotate sweeper members 242 above the screen 100 to spread input material over the ragging and screen 100.

[0194] Figure 6B shows the components of the apparatus 600 in a partially disassembled cross-section diagram, and 6C shows an assembled cross-section which illustrates the arrangement of structures in the apparatus 600.

[0195] The structure 201 defines a ring of sub-chambers 222 which form segments of an annular ring below the screen 100. Each sub-chamber 222 is separated from adjacent subchambers by radially extending side walls 623 to which baffles 235 are attached below the screen 100. The baffles 235 are cylindrical, i.e., vertical in cross-section, but may be replaced with baffles which are angled or curved in cross-section, as discussed in relation to apparatus 200.

[0196] The compressor 230 is connected to a bottom of the structure 201 to form a central plenum 232 to supply pressurised air to the ring of sub-chambers 222. Within the plenum 232, the apparatus further comprises an air flow regulator 632 which is coupled to a regulator motor 634 fixed to the structure 201 and configured to rotate the air flow regulator 632 within the plenum 232 about a central axis 601 of the apparatus 600.

[0197] The air flow regulator 632 comprises a cylindrical drum with an open bottom configured to receive pressurised air from the compressor 230 and defining an aperture 633 in the side wall configured to deliver pressurised air from the plenum 232 to the sub-chambers 222. As the air flow regulator 632 is rotated, the aperture 633 is sequentially rotated into alignment with each of the sub-chambers 222, so that each sub-chamber receives a pulse of higher pressure as the aperture 633 passes.

[0198] The air flow regulator 632 of the apparatus 600 has only one aperture 633, but could have more apertures, in other embodiments, to increase the frequency of pressure pulses in the sub-chambers 222. Different apertures 633 may be provided at different parts of the air flow regulator 632 to provide different air flow characteristics, or different pressure pulse frequencies or durations.

[0199] In some embodiments, the apparatus 600 may include seals or gaskets to limit air flow around the air flow regulator 632 and restrict air to flow only through the aperture(s) 633. In other embodiments, the apparatus 600 may not include seals around the air flow regulator 632 so as to allow the sub-chambers 222 to be provided with a constant back pressure (i.e., pressure above atmospheric or ambient pressure), with repeated pulses of higher pressure above the back pressure.

[0200] The magnitude of the pressure pulses can be adjusted by adjusting the pressure delivered by the compressor 230 (e.g., adjusting the fan speed). The frequency of the pressure pulses can be adjusted by adjusting the rotation speed of the air flow regulator 632.

[0201] The structure 201 also comprises a central support cylinder 605, which houses the regulator motor 634 and supports the sweeper mechanism 240. The sweeper mechanism 240 comprises an outer cylinder 645 which is coupled to a sweeper motor 640 fixed to the support cylinder 605 of the structure 201.

[0202] The sweeper members 242 are connected to the outer cylinder 645 (directly or indirectly) and rotate with the outer cylinder 645 relative to the structure 201 to sweep material across the screen 100.

[0203] The apparatus 600 comprises a feed hopper 610 where mixed input material can be deposited for processing by the apparatus 600. The feed hopper 610 comprises a cylindrical wall connected to the outer cylinder 645 with an annular space between the outer cylinder 645 and the feed hopper wall, which extends up above a height of the outer cylinder 645.

[0204] The feed hopper 610 defines a material input region 210 where the material mixture 110 can be fed into the apparatus 600 via an open top of the feed hopper 610. The material then falls down through the annular gap between the feed hopper wall and the outer cylinder 645 and falls down around the outer cylinder 645.

[0205] At the bottom of the outer cylinder 645 is a plurality of feed blades 646 extending away from the outer cylinder 645 to an inner support ring 647, as shown in Figures 6 A, 6B and 6F. The inner support ring 647 supports the feed material so that it doesn’t spill over to the screen 100 too quickly. The feed material is distributed by the feed blades 646 through a between the feed blades 646 and the structure 201 and progresses radially outward under the inner support ring 647 before reaching the sweeper members 242 and the screen 100.

[0206] The sweeper mechanism 240 may further comprise a secondary support ring 648 arranged concentrically outside the inner support ring 647 to catch any material which overflows the top of the inner support ring 647.

[0207] The sweeper members 242 extend out from the inner support ring 647 (and/or secondary support ring 648) across the screen 100 towards an outer circumferential edge of the screen 100. The sweeper members 242 do not extend directly radially away from the inner support ring 647, but are swept back at an angle relative to the radius and the direction of rotation, such that the sweeper members 242 sweep the material out radially across the screen 100 as well as partially circumferentially.

[0208] The sweeper members 242 may comprise any suitable profile and material, as discussed previously. The sweeper members 242 of apparatus 600 comprise 10mm square profile elongate bars, which may be formed of steel, such as structural steel or mild steel, for example.

[0209] The outer ends of the sweeper members 242 are supported by an outer support ring 649 which in turn is supported by the structure 201 via spacer wheels 609. A plurality of spacer wheels 609 are coupled to an outer circumferential region of the structure 201 and allowed to rotate so that the outer support ring 649 can rest on the wheels 609 to maintain a height of the sweeper members 242 above the screen 100.

[0210] The spacer wheels 609 may be mounted on the structure 201 with adjustable brackets (e.g., with slotted holes and mechanical fasteners), to allow the height of the outer support ring 649 and sweeper members 242 to be adjusted. The height of the outer cylinder 645 may also be adjusted by installing spacers between the outer cylinder 645 and the structure 201. In this way, the thickness of the material bed 110 above the ragging bed 105 can be adjusted for processing different materials. [0211] The channel 250 extends circumferentially around an outer edge of the screen 100 and the sweeper members 242 are arranged to sweep material from the top of the ragging bed into the channel 250.

[0212] The sweeper mechanism 240 further comprises paddles 650 connected to the outer support ring 649 which extend down into the channel 250 to push material along the channel 250 towards the channel outlets 255. A bottom of the channel 250 slopes down towards the outlets 255 to encourage material to fall into the outlets 255, and the material can then be removed with a conveyor or container, for example.

[0213] The various embodiments of the apparatus described allow for different process parameters to be adjusted for separation of different target materials, such as minerals, from various mixtures of materials, such as mined ores, for example.

[0214] Using the apparatus 600 shown in the drawings, the inventors have adjusted the settings to target specific minerals. The variable speed motors allow for adjustment of the air flow regulator speed, sweeper speed, and fan speed to adjust air pressure and flow.

[0215] The optimal process parameters will vary depending on the target material, mixture composition, moisture level, and the specifications of the apparatus. For exemplary purposes, the following parameters have been successful in processing the following materials.

[0216] The ragging is arranged on the screen 100 to cover a single layer in its entirety, and in some cases part of a second layer (e.g., 1.5 layers covers 50% of second layer, 1.75 layers covers 75% of second layer).

[0217] The tungsten target material in the table refers to wolframite (sg 7-7.5) and scheelite sg (5.9-6.1) as target minerals which comprise tungsten.

[0218] The moisture of the feed material was below 1.5% for most cases in the table above, and the moisture level when targeting tungsten is shown in the left column (2.4%, 1.9%, 1.3%, 1.2%). With higher moisture levels, higher air flow may be beneficial to help agitate the material and partially dry it. The ragging coverage may also be increased.

[0219] In general, the pressure and air flow may be adjusted so that the bulk of the material is lifted above the screen by a level in the range of 50mm to 300mm, 100mm, to 200mm, or about 150mm, for example.

[0220] The pressure and air flow rate required to do this will also vary depending on the materials, conditions, and specifications of the apparatus. For example, the average chamber pressure may be in the range of lOPa to lOOOPa, 50Pa to 500Pa, or 60Pa to lOOPa above ambient atmospheric pressure. The magnitude of the pressure pulse may be greater than the average pressure by a factor of at least, 3, 4, 5, 6, 8, 10, 20 or 30, for example.

[0221] At the peak of the pressure pulse, the air flow velocity through the screen 100 may be in the range of Im/s to 20m/s, 5m/s to 15m/s, 8m/s to 12m/s, or about lOm/s, for example.

[0222] The frequency of the pressure pulses may be in the range of 1Hz to 10Hz, 2Hz to 8Hz, 3Hz to 6Hz, 4Hz to 5Hz, or about 4.5Hz.

[0223] The duration of the pressure pulse may be a fraction of the period between pressure pulses, the fraction being in the range of 5% to 25%, 6% to 20%, 8% to 16%, 10% to 14%, or about 12%, about 12.5%, about 6%, or less than 25%, less than 20%, or less than 15%, for example. The duration of the pressure pulse may be in the range of 10ms to 100ms, 15ms to 50ms, or 20ms to 30ms, for example. [0224] The above process parameters are provided for exemplary purposes only, and may be varied in different embodiments to suit the conditions and specifications of a given material and apparatus.

[0225] An alternative embodiment is described below in relation to Figures 7 and 8.

[0226] The process is able to be constructed into different shaped sorters. The preferred embodiment is a round shape where material is deposited onto the centre of the sorter. The material is then moved outwards onto metal screen sizing beds by use of sweeper arms (11) which are raked in an angular fashion. Rotation of the arms in a circular fashion contributes to the movement of material across the beds. Compressed air (7) is passed into a number of chambers (4) linked in a circle under the beds forming a complete circle. Each of these chambers is fed compressed air from a fan, blower or compressor (7) located underneath the sorter. This air is pumped under pressure in pulsating waves in a circular manner around the sorter. On meeting the directional baffles (8) placed inside the chambers, air is deflected upwards into the screening beds (3) above the chambers.

[0227] The air flow and sweeper arms are controlled by variable speed drives allowing for increases and decreases of pressure/speed to occur in each chamber. Directional baffles (8) in the chamber allows for the air flow to be concentrated in a particular direction or diffused into an even amount of air flow throughout the entire chamber (9). Increases and decreases in the air flow allow for alterations to the fluidisation of the material lying on the bed above the chamber.

[0228] The screening bed (3) above the chamber is able to be sized accordingly and is not restricted to one size for the entire sorter. Different sized screens allow for the collection of different size materials in one pass. This is particularly important with the collection of gemstones. For example, cost of recovery of small sapphires usually outweighs their commercial value. This process allows for the recovery of the small sapphires at the same time as recovering commercially viable larger gemstones. The sorting of the smaller sapphires into one collection point makes it economically viable to recover these stones.

[0229] The use of ceramic style ragging (16) allows for variation in specific gravity, while at the same time eliminating locking of the screening material due to moisture and rust related issues. Most use within industry is for steel ragging which is subject to locking together and requires beds to be raked to break the ragging apart. The use of ceramic material in the bed removes this requirement. The adjustability of the specific gravity means a variety of material can be processed through the sorter by minimal changes.

[0230] As the material passes over the beds, the compressed air pulses upwards from the baffled (8) chambers (9) under the beds causing the beds to fluidise and then stratify. The use of air as opposed to water also allows for the presence of fines within material in that most fines become mud like when moistened. The use of air does not cause this and allows for the collection of targeted material in the fines.

[0231] As the beds are pulsed by the compressed air, the sweeper bars (11) move the lighter product outwards towards the waste collection areas on the outside of the sorter. The combination of pulsing air movement, gravitational effect on the targeted material, the sweeper bar action and the appropriate specific gravity ceramic bedding material cause the targeted material to fall through the bed into a collection point in each chamber. These collection points are designed to fill the entire area of the chamber and slope inwardly to allow easy flow of the targeted material into a collection chamber at the bottom of the assembly. Exit of material from this point is via a spigot arrangement. Larger pieces of the target material are collected on the bed and remain there until removed as part of a batch recovery action.

[0232] The waste product is caught in an open topped collection tunnel (5) on the outside of the sorter. This tunnel is sloped in such a manner to allow for the waste material to fall downwards away from the body of the sorter. This material is then removed by conventional methods.

[0233] The target material is allowed to fall through the beds into the chamber below the screens and is collected either from the sloped collection chamber as required or through a spigot arrangement where the targeted material falls through the spigot into a collection point or is also conveyed away by conventional means. Size of the spigot is such that it does not interfere with back pressure in the chamber. 25mm is the maximum diameter of the suitable spigots. [0234] Rectangular or square configurations are also possible. Material is conveyed conventionally to the top of the sorter rather than the centre in this case. Sweeper arms are angular and push the material towards one side of the sorter. The sweeper arms are chain driven and linked like tracks on top of and underneath the sorter.

[0235] In this variation, compressed air is fed into the side of the chambers rather than underneath and baffles are placed at right angles to the air flow direction.

[0236] The waste collection occurs on the opposite side of the sorter from the ingress point of the air flow. This allows for a single collection chute to capture waste product and convey it away from the sorter by conventional means.

[0237] The process for the sorting of material regardless of the shape of the sorter is the same. Air flow, gravitational effect, specific gravity and sweeper arm movement controls the flow and collection of material on the sorter.

[0238] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. A process for separating a target particulate material from a mixture of particulate materials of different densities, the process comprising: placing the mixture on a bed of non-metallic ragging supported by a filtering screen; and forcing gas upwards through the screen and ragging bed to agitate the mixture and separate the target material from the rest of the mixture, with the target material on one side of the ragging bed and the rest of the mixture on the other side of the ragging bed.

2. The process of claim 1, wherein a density of the ragging material is greater than a density of the target material, and the process further comprises removing the target material from above the ragging bed.

3. The process of claim 1, wherein a density of the ragging material is less than a density of the target material, and the process further comprises removing the target material from below the ragging bed.

4. The process of claim 3, further comprising collecting at least part of the target material from below the screen.

5. The process of claim 3 or 4, further comprising: removing the rest of the mixture from the ragging bed; removing the ragging from the screen; and collecting any remaining part of the target material which is too large to pass through the screen.

6. The process of any one of claims 1 to 5, wherein the ragging is formed of a ceramic material.

7. The process of any one of claims 1 to 6, wherein the gas is forced through the screen and ragging bed periodically in repeated pulses of pressure.

8. The process of claim 7, wherein at least part of the agitated mixture is allowed to settle onto or into the ragging bed due to gravity between the pulses of gas pressure.

9. The process of claim 8, wherein at least part of the agitated mixture is removed before it can settle onto the ragging bed.

10. The process of any one of claims 1 to 9, further comprising applying additional treatment steps to the target material to remove different contaminants or separate other target materials.

11. An apparatus for separating a target particulate material from a mixture of particulate materials of different densities, the apparatus comprising: a filtering screen defining a plurality of apertures of a size selected to allow passage of particles below a certain size; a structure configured to support the screen and configured to support a bed of loose ragging on top of the screen during operation of the apparatus, the structure defining a chamber below the screen and a collection outlet at a bottom of the chamber to allow processed material to be removed from the chamber; and a gas compressor configured to supply the chamber with pressurised gas, during operation of the apparatus, such that gas flows upwards through the screen to agitate particulate material placed on the ragging bed, wherein the compressor is configured to force gas through the screen and ragging bed periodically in repeated pulses of pressure, and wherein the compressor is configured such that the frequency and magnitude of the pressure pulses can be selected by a user and adjusted for different sorting processes.

12. The apparatus of claim 11, further comprising one or more baffles in the chamber configured to direct gas flow towards the screen.

13. The apparatus of claim 12, wherein a position and orientation of the one or more baffles in the chamber is adjustable allowing the gas flow through the screen to be altered for different applications.

14. The apparatus of any one of claims 11 to 13, further comprising one or more sweeper members connected to a sweeping mechanism which is configured to move the one or more sweeper members across the screen at a set height above the screen to spread the mixture of particulate materials over the ragging bed during operation.

15. The apparatus of claim 14, wherein the structure further defines a channel at or near one or more edges of the screen, and wherein the sweeping mechanism and sweeper members are configured to push some at least part of the mixture of particulate materials into the channel for collection.

16. The apparatus of claim 14 or 15, wherein the speed of the sweeping mechanism is adjustable.

17. The apparatus of any one of claims 14 to 16, wherein the sweeper members are flexible and configured to bend to pass oversized particles on the ragging bed.

18. The apparatus of any one of claims 14 to 17, wherein a height and angle of the sweeper members are adjustable relative to the screen.

19. The apparatus of any one of claims 11 to 18, wherein the screen is removable and able to be replaced with different screens defining different aperture sizes.

20. The apparatus of claim 19, wherein the screen comprises independent sub-screen panels, each able to be removed and replaced with different screens defining different aperture sizes.

21. The apparatus of claim 20, wherein the structure further comprises dividing members between each of the sub-screen panels configured to separate the ragging bed into different regions configured to accommodate different ragging materials associated with corresponding sub-screen panels.

22. The apparatus of claim 21, wherein the structure defines a plurality of collection outlets, each associated with a corresponding one of the sub-screen panel.

23. The apparatus of any one of claims 20 to 22, wherein the structure defines a plurality of sub-chambers, each associated with a corresponding one of the sub-screen panels.

24. The apparatus of any one of claims 11 to 23, wherein the structure and screen are substantially round and the apparatus is configured to process particulate material conveyed to a centre of the apparatus and spread out radially over the screen towards an outer edge of the screen.

25. The apparatus of any one of claims 11 to 23, wherein the structure and screen are substantially rectangular and the apparatus is configured to process particulate material conveyed to one side of the apparatus and spread out linearly over the screen towards an opposite side of the screen.

26. The apparatus of any one of claims 11 to 25, further comprising a dust cover to restrict dust from escaping the apparatus.

27. A kit comprising: an apparatus according to any one of claims 11 to 26; and loose ragging material configured to form a ragging bed over the screen.

28. The kit of claim 27, further comprising a set of interchangeable screens with different aperture sizes and associated ragging materials of different diameters.

29. The kit of claim 27 or 28, further comprising different ragging materials having different densities.

30. The kit of any one of claims 27 to 29, further comprising one or more conveyors for moving material to or from the apparatus, and a vehicle to facilitate transport of the apparatus and one or more conveyors.