Mineral ore separation is an important function within a broader mineral processing plant. The efficiency, size and weight of the plant equipment are critical factors., particularly on sites where space is limited, or the area surrounding the equipment is confined, thereby making it more difficult to maintain and/or manipulate heavy plant and equipment, Separation is used to concentrate the ore by separating it from the gangue. Some typical separation equipment separates dry feed and other types operate on wet feed by incorporating the material to be separated into a slurry.

Common separation apparatus may utilize a moving or a static screen. Also the screen may be horizontal or inclined.

The common problem associated with this type of equipment is its size. Typically, the screens are long, and the separation process is a linear one. This takes up a lot ofspace, and may also carry a significant weight which may adversely impact installation and maintenance of the equipment.

One of the problems associated with the design of separation equipment utilising vibratory screens, especially as the equipment is reduced in size, is the migration of ragging upon the screen. Due to the influence of the incoming stream of material to be separated, or to other, factors like vibration harmonics, or uneveniiess in the flatness of the screen, or if the screen is tilted slightly, tire ragging can move over time and concentrate in a particular area of the screen, thereby severely reducing the effecti veness of the separation operation. if is a goal of the present invention to ameliorate at least some of the aforementioned problems.

Disclosure of the Invention

Accordingly, the present invention is a ragging bed for use in a mineral separation apparatus having a screen that includes multiple separation zones including;

at least two weirs, and

- a distribution pot, and

- ragging,

wherein the at least two weirs are included upon the screen, and the distribution pot is positioned centrally upon the screen, and the at least two weirs, in combination with the side- wail of the distribution pot, create a plurality of chambers therebetween into which sufficient ragging is loosely placed and contained upon the screen.

Preferably the bed is circular shaped.

Preferably the weirs are located at .appropriate radial distances from the distribution potj and extend in a circular direction about the screen, to -thereby combine to create radially adjacent concentric weir rings, and the plurality of concentric ring shaped chambers are defined between adjacent weir rings, or the innermost weir ring and the outermost periphery of the pot, so that the entire area of the screen between the sidewatl of the distribution pot and the outer periphery of the screen is effectively covered by the pl urality of concentric ring shaped chambers.

Optionally a plurality of additional weirs are included upon the screen that extend in radial lines at least partway out to the outer periphery of the screen from the distribution pot, and intersect with at least some of the circular directed weirs, to thereby create a plurality chambers within at least one of the conceit trie ring shaped chambers.

Preferably the bed is forcefully and quickly vibrated in order to vibrate the screen and agitate the raggmg within each respective chamber. Preferably the ragging placed within each chamber has a particular size, shape, quantity and specific gravity, to give the each of the chambers distinct separation capabilities within the apparatus, so that by varying the ragging's properties for each chamber, multiple separation zones are created upon the screen that best suit the qualities of tire material to be separated.

Preferably the distribution pot is positioned directly under the incoming flow of a slurry that carries the ore to be separated, and when the flow of slurry impinges upon the distribution pot, the distribution pot redirects the flow so that the slurry is effectively evenly distributed upon the innermost ring of chambers whereat the slurry undergoes a first stage of separation within that ring, and any slurry remaining flows radially outwardly to the next ring of chambers whereat a second stage of separation occurs, and so on until the remaining slurry reaches the outer periphery of the bed, whereat it overflows the edge of the bed.

In another form, the present invention is a method of creating a ragging bed with multiple zones having distinct separation properties, the method including the following steps:

a) providing a screen, and

b) placing a di str ibution pot in the centre of th e screen, and

c) placing at least two weirs at radially spaced apart locations upon the screen, relative to the distribution pot, to thereby create distinct chambers between either adjacent weirs, or the innermost weir and the outermost wall of the pot so that effecti vely the entire area of the screen is covered by a plurali ty of chambers, and d) filli ng each chamber with distinct ragging that has the separation properties that is appropriate for the feed of material to be separated , and

e) vibrating the bed so that the ragging is sufficiently agitated, and

f) feeding a flow of material at a suitable flow rate into the distribution pot so that the flow is redirected out of the pot and evenly distributed into the innermost chamber, whereat a first stage of separation occurs, and

g) continuing to vibrate the bed so that remaining material in the innermost chamber is substantially evenly distributed into the adjacent chamber, and so on, until the remaining material overflows the outermost edge of the bed. In another form, the present invention is a method of creating a ragging bed with multiple zones having distinct separation properties, the method including the following steps:

a) providing a screen, and

b) placing a distribution pot in the centre of the screen, and

c) placing at least two weirs at radially spaced apart locations upon the screen, relative to the distribution, pot, to tliereby create distinct chambers between either adjacent weirs, or the innermost weir and the outermost wall, of the pot so that effectively the entire area of the screen is covered by a plural ity of chambers, and d) placing a. plurality of radially directed weirs that extend from the distribution pot and the outermost, edge of the screen that intersect with the radially spaced apart weirs to thereby create additional chambers within the chambers formed by the radially spaced apart weirs, and

e) filling each chamber with distinct ragging that has the separation properties that is appropri ate for the feed of material to be separated, and

f) vibrating the bed so that the ragging is sufficiently agitated, and

g) feeding a flow of material at a suitable flow rate into the distribution pot so that the flow is redirected out of the pot and evenly distributed into the innermost plurality of chambers, whereat, a first stage of separation occurs, and

h) continuing to vibrate the bed so that remaining material in the innermost plurality of chambers is substantially evenly distributed into the adjacent plurality of chambers, and so on, until the remaining material overflows the outermost edge of the bed ,

Brief Description of the Drawings

Figure 1 is a cut-away isometric view of a typical pressurised mineral separation apparatus featuring the present invention. Detailed Description of the Preferred Embodiments

In Figure 1 we are shown a mineral separation apparatus 1 . It can be seen that the apparatus has an outer body that has a conieally shaped lower body portion 3, and an upper body portion 7 having a substantially vertical side wall. The volume of the apparatus 1 in the upper portion of the body is typically pressurised.

Housed within the apparatus is an inner body 9. The shape of the inner body 9 closely matches the shape of the outer body, A substantially even gap 5 is maintained between the inner and outer bodies.

The inner body 9 is supported upon the support frame 1 1. The separation screen 15 is located at the top of the inner body 9. The separation screen 15 effectively extends acro ss th e top of the inner body 9. A distributor pot 17 is lo cated in the centre of the screen 15. The outer body has a lid 19 that includes a slurry inlet port 21 that is located above the distributor pot 17.

An electric motor 13 is configured to rapidly vibrate tire screen 15 during operation of the apparatus.

The screen 15 has a plurality of concentric weirs 23 at a various radial distances from the distributor pot 17. Optionally there are also a plurality of radially extending weirs 25 that extend outwardly from the distributor pot 17 to the periphery of the screen 15, Weirs 23 and 25 intersect and combine to create a plurality of chambers 27.

Ragging is the typical name given for the particulate material that is used in combination with the screen to provide efficient separation within the apparatus. Typically, the ragging is spherically shaped, however other shapes may be used. The size, shape, quantity and specific gravity of each particle of ragging used in combination with the screen is selected to best match the properties of the ore slurry being separated by the apparatus. As the screen is rapidly and forcefully vibrated by the electric motor, the ragging is agitated, and it bounces upon the screen and collides between adjacent particles, of ragging, and interacts with the slurry. This creates a dynamic ragging bed that plays a critical role in the separation process.

The specifi c gravity of the ragging is specifically chosen to match the properties of the ore or the gangue contained within the slurry. The particulate matter entrained in the slurry interacts with, the ragging particles and this causes lighter material to "float" above the dynamic ragging, while heavier material is able to sink into the ragging bed and eventually pass alt the way through the ragging bed and the screen into the collection hutch 29 which exists in the void underneath the screen in the inner body 9.

The slurry to be processed contains both ore and gangue. Gangue is the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. Depending on the properties of the ore to be separated from the gangue, sometimes the ore is the heavy component and the gangue is lighter, and in oilier circumstances it is the opposite way around.

The following description will use. one example for illustrative purposes only for the present invention where the ore is heavier than the gangue. The same fundamental principles are in play when the opposite arrangement occurs, where the ore is lighter than the gangue. in this example, when the heavier ore passes through the ragging bed and screen, the hutch 29 is called a "concentrate hutch", and the gangue "floats" above the agitated ragging bed. After the first stage of ore separation has occurred, the concentration of ore entrained in the remaining slurry is diminished, while the concentration of gangue is increased. The modified slurry then flows outwardly to the next eoneeiitric ring of chambers 27 where it interacts with a ragging bed having different separation properties. In this ring of chambers 27, even more ore is then separated from the slurry, and the concentration of gangue in the lighter material floating above the ragging bed is further increased. This is repeated as the slurry flows towards the outer periphery of the screen and engages each subsequent group of separation chambers 27.

By the time the slurry reaches the outer periphery of the screen, the concentration of any remaining ore has diminished to the point where it may no longer be commercially viable to continue with the separation process. The slurry- containing the highest concentration of gangue, known as "tailings" then overflows the screen and flows into the gap 5, known as the "tailings launder". It may be viable to have another separation apparatus with different properties in series with a primary separating apparatus to further process the tailings from the primary separating apparatus.

By having the separation properties of each chamber group tailored to match the changing properties of die -slurry as the ore-gangue concentration is altered by its interaction with the previous chamber group, the separating apparatus can be far more efficient at its task of ore separation.

By having the volume predominately above the separation bed in the upper body 7 pressurised, then there is a greater force imposed on the slurry to force it to interact with, the ragging bed and for the ore to pass through the screen. The pressure also provides force to the tailings to make it flow away from the vicinity of the separation bed.

The closed outer body also entraps fine particulate matter that would otherwise escape from the apparatus and potentially cause pollution problems.

A. typi cal example of an are that is heavier than its gangue is gold. The gold is able to pass through the ragging bed and the screen and is concentrated in the hutch 29 and the tai l ings, containing the highest concentration of gangue , overflows do wn the gap 5 and out of the apparatus. The opposite typically occurs when an ore like coal is being processed. Typically coal ore is .lighter than its gangue, and it is the gangue that passes through the ragging bed and screen. The collection hutch 29 then becomes a. tailings hutch. The concentrated ore floating above the ragging bed eventually overflows the separation bed and passes out of the app aratu s via the gap 5.

Typically, the pressure maintained within the apparatus is about 150KPa. Typically, the electric motor 13 forces the separatum bed to oscillate approximately 40 to 180 oscillations per minute. Typically, each ragging particle is spherically shaped and has a diameter in the range of 6mm to 32mm. Typically, they are each double the size of the aperture in the screen , Typical arrangements include the electric motor providing a forced upward stroke, and then allows the separation bed to ireefall back. In another arrangement, the electric motor forces both the upward and downward strokes. Typical stroke lengths are in the range of 10mm to 50mm.

The ore slurry to be separated is fed into the apparatus through the inlet port 21 and it impinges upon the distributor pot 17, The distributor pot 17 is designed to redirect the slurry flow so that it is effectively evenly distributed onto the first concentric ring of chambers 27 nearest to the distributor pot 17. Tire slurry then undergoes a first stage of separation. Any remaining shiny then flows radially outwardly into the adjacent ring of chambers 27 where in it undergoes a second stage of separation. In the present invention, there are many aspects of the invention that can be adjusted to maximize the separation efficiency of the apparatus. The size of the apparatus can be scaled up to provide a screen with greater surface area so that it can efficiently handle higher flowrates of slurry. The number of concentric rings of chambers can be increased or reduced during equipment design to match the specific properties of the ore to be separated, and the fiowrate of the slurry.

Another one of the advantages of the present in vention is that the separation apparatus provides comparatively equal or greater separation performance and throughput as other more traditional methods of ore separation that have a linear operation, but in a more compact and lighter configuration.

While the above descripti on includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.

It will be also understood that, where the word "comprise", and variations such as "comprises" and "comprising", are used in this specification, unless the contest requires otherwise, such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.

The reference to any prior art in this specification is not and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.