Integrated separator system and process for preconcentration and pretreatment of a material

Abstract

The invention provides an integrated separator system for the preconcentration of a material comprising one or more grizzly bars and one or more electrodes which provide a high voltage pulse (HVP) discharge to the material. The invention also provides a process for preconcentration of a material preferably a mineral within a rock which comprises: providing the material into an integrated separator system comprising one or more grizzly bars and one or more electrodes which are capable of providing at least one high voltage pulse discharge(s) to the material; applying one or more high voltage pulse discharge(s) to the material as the material is travelling along the grizzly bar(s) to preferentially disintegrate the particles containing mineral grains of high conductivity/permittivity; separating the disintegrated particles by way of the grizzly bar(s) resulting in the separation of the feed material into low grade (oversize) and high grade (undersize) products; and wherein the disintegrated particles from step b) pass through a screening element for further treatment. The present invention also relates to a process for comminution of a material.

Claims

1. An integrated separator system for the preconcentration of a material, the system comprising a grizzly screen having a plurality of grizzly bars, and spacing between bars of the plurality of grizzly bars allows disintegrated particles of the material to pass through the grizzly screen while non-disintegrated particles are retained on top of the grizzly screen; wherein the grizzly bars act as electrodes which provide a high voltage pulse (HVP) discharge to the material; wherein the HVP discharge is applied at a voltage and energy sufficient to disintegrate particles of the material containing high conductivity or high permittivity minerals; and wherein particles that do not contain high conductivity or high permittivity minerals are protected by particles containing high conductivity or high permittivity minerals and are not broken.

2. The separator system of claim 1, wherein the grizzly screen comprises grizzly bars which act as alternating positive and negative electrodes of a screen element.

3. The separator system of claim 1, wherein the grizzly screen acts as a negative electrode and a positive electrode is located above the grizzly screen.

4. The separator system of claim 1, wherein the grizzly bars are cylindrical or rectangular in cross-sectional shape.

5. The separator system of claim 1, wherein a gap between the grizzly bars is set between 10 to 200 mm.

6. The separator system of claim 1, wherein the grizzly bars are rectangular in cross sectional shape and are substantially parallel to each other.

7. The separator system of claim 1, wherein the grizzly bars are rectangular in cross sectional shape and are arranged in a cone shape with a first end of the grizzly bars having a larger gap therebetween than compared to a second end of the respective grizzly bars.

8. The integrated separator system according to claim 1, wherein the system is used to remove sulphide minerals selected from the group comprising pyrite or other mineral matters having higher conductivity/permittivity than coal to improve coal quality and to reduce environmental impact.

9. A process for preconcentration of a material preferably a mineral which comprises: a) providing the material into an integrated separator system comprising one or more grizzly bars and one or more electrodes which are capable of providing at least one high voltage pulse discharge(s) to the material; b) applying one or more high voltage pulse discharge(s) to the material as the material is travelling along the grizzly bar(s) to preferentially disintegrate the particles containing mineral grains of high conductivity/permittivity; c) separating the disintegrated particles by way of the grizzly bar(s) resulting in the separation of the feed material into low grade (oversize) and high grade (undersize) products; and wherein the disintegrated particles from step b) pass through a screening element for further treatment.

10. A process for preconcentration of a material according to claim 9, wherein the material is a mineral within a rock.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The invention will now be described, by way of example only, and with reference to the accompanying figures. It will be appreciated that the figures are provided for illustration of the invention only and should not be construed as limiting the generality and scope of the invention as provided by the claims.

(2) FIG. 1 shows a top view of the integrated high voltage pulse discharge separator system with the grizzly screen which is used to disintegrate the high grade ore particles and to separate the high grade and the low grade ore particles by size according to a first preferred embodiment of the invention.

(3) FIG. 2 shows an expanded front and side view of a pair of grizzly bars which act as electrodes in the integrated high voltage pulse discharge separator system with the grizzly screen which is used to disintegrate the high grade ore particles and to separate the high grade and the low grade ore particles by size according to a second preferred embodiment of the invention.

(4) FIG. 3 is a schematic view of a third preferred embodiment of the invention which provides an example of multi-stage treatment of RoM ore using the integrated separator system and process of the present invention which does not require the RoM ore to be pre-screened.

(5) FIG. 1 illustrates the integrated high voltage pulse discharge and the grizzly screen separator system (100) and process for preconcentration of an ore material.

(6) The integrated separator system (100) combines the high voltage pulse discharge and screen separation functions in a grizzly screen which comprises a plurality of grizzly bars (101 & 102). Each grizzly bar acts as an electrode, with every second grizzly bar acting as a positive electrode (101) and the alternate grizzly bars acting as negative electrodes (102).

(7) Ore particles in a given size fraction are fed onto the top of the grizzly screen. The grizzly bars in the grizzly screen are arranged with a predetermined gap to be able to retain the ore particles in the given feed size. The grizzly bars/screen operates with an inclined angle to allow ore particles to travel along the bars due to gravity. High voltage pulses are discharged in the vicinity of the grizzly bars 101 or 102 in a controlled frequency to create a horizontal pulse discharge zone between the positive electrode (101) and the negative electrode (102) while the ore particles are travelling along the grizzly bars/screen.

(8) Particles containing a high grade of conductivity/permittivity minerals (shown as the black solid particles in FIG. 1) will attract the pulse discharge energy and will be preferentially disintegrated by plasma channel expansion through the body of the ore particles. Particles that do not contain high grades of conductivity/permittivity minerals (shown as the white particles in FIG. 1) will be “protected” by those containing high conductivity/permittivity minerals and will not be broken while both particles travel through the high voltage pulse discharge zone.

(9) The disintegrated higher grade particles will drop through the grizzly bars and be collected as an undersized product; while particles with low grade or barren rocks will not be broken by the pulses, and will be retained on top of the grizzly bars and discharge at the end of the grizzly as an oversize product.

(10) Thus the feed ore when passing through this integrated separator system will be split by grade. The bar length, inclined angle, pulse charge frequency, pulse energy can be designed to effectively split feed ore by grade.

(11) FIG. 2 demonstrates a further preferred embodiment of the integrated separator system and also of the process of the present invention for the step of applying one or more high voltage pulse discharge(s) to feed ore particles in the integrated high voltage pulse discharge and the grizzly screen system. In this preferred embodiment, the whole grizzly screen comprising a plurality of grizzly bars is used as the negative electrode (202), while the positive electrode (201) is located above the grizzly screen/bars. The gap between the plurality of grizzly bars (202) and the distance between the electrodes (from 201 to 202) are arranged to retain the feed ore particles on the grizzly and allow free movement of the feed ore particles between the electrodes 201 and 202 in accordance with the feed ore size range. When ore particles move along the inclined grizzly bars (202) and pass through the vertical high voltage pulse discharge zone, the high grade ore particles will preferentially attract the pulse discharge energy and be disintegrated. The broken fragments will drop through the gap of the grizzly bars (202) and be collected as an undersized product. The low grade ore or the barren rocks will pass the pulse discharge zone without substantial body disintegration. These low grade feed particles will be retained on the top of the grizzly bars and become the oversize product.

(12) When a plurality of ore particles are presented to the high voltage pulse discharge field, the spark energy selectively goes through those ore particles containing high conductivity/permittivity minerals and breaks these ore particles into small fragments. While barren or low grade rocks that contain less high conductivity/permittivity minerals will not receive the same level of spark energy and they are “protected” by the particles containing high conductivity/permittivity minerals and are hence not broken. Therefore in the multi-particle treatment applications such as illustrated in FIGS. 1 and 2, the spark energy is used more efficiently as it preferentially breaks metal-bearing particles.

(13) It should be understood that the ore particles shown in FIG. 2 containing a high grade of conductivity/permittivity minerals are shown as the black solid particles in FIG. 2. These ore will attract the pulse discharge energy and will be preferentially disintegrated by plasma channel expansion through the body of the ore particles.

(14) Particles that do not contain high grades of conductivity/permittivity minerals are shown as the white particles in FIG. 2 which will be “protected” by those containing high conductivity/permittivity minerals and will not be broken while both particles travel through the high voltage pulse discharge zone.

Example

(15) In a particular example of the present invention, the following was performed using an Australian copper ore, approximately 14 particles per batch in a size range of 19 to 26.5 mm which were treated in a high voltage pulse processing system. 15 batches of tests, treating 3.8 kg of particles in total, were repeated to increase statistical confidence. A total of 3.8 kWh/t specific spark energy was used in the process. The pulses selectively disintegrated some particles, whilst others were left intact. The product was sized and assayed.

(16) A yield of 25% feed particles by mass was retained on the parent 19 mm size, which was assayed to contain 0.15% copper. While the copper grade of the undersize product was 0.37%.

(17) In this example, the high voltage pulse treatment followed by size based separation effectively split the feed ore into low grade and high grade products.

(18) FIG. 3 illustrates a schematic flowsheet using the process of the present invention to treat the entire RoM feed ore without the pre-screening requirement. The process is undertaken in multiple stages of treatment using the process and integrated separator system of the present invention.

(19) In a first treatment stage, the gap between grizzly bars is set at 100 mm. Material smaller than 100 mm from the RoM ore will drop to the screen undersize. Material retained on the set of grizzly bars will be subjected to high voltage pulse treatment. Those particles that remain intact or remain on the top of the grizzly screen after passing through the pulse discharge field will be discharged as an oversize product. The undersize product material will then be subjected to a second treatment stage, with a grizzly bar gap set at 50 mm. The process repeats for a third stage at 25 mm grizzly bar gap, and for a fourth and final stage at a 10 mm grizzly bar gap.

(20) The grizzly bar/electrode configuration as described above and as shown in FIG. 1 can be used in the first two stages with a gap setting larger than or equal to 50 mm. The grizzly bar/electrode configuration as described above and as shown in FIG. 2 can be used in the last two stages with a gap setting smaller than 50 mm.

(21) The integrated ore grade splitting system as shown in FIGS. 1 and 2 has a large throughput capacity and a small floor space, and can be operated in a continuous mode. The system can be designed in multiple layers for the flowsheet application as presented in FIG. 3. In this arrangement, the undersize product from the top grizzly drops to the next layer of grizzly that has a smaller gap between the grizzly bars.

(22) The RoM ore can contain metal scats from the mining process. The metal scats may have a tendency to affect the high voltage pulse efficiency in the preconcentration process. If this happens, a metal detector and a metal removal facility can effectively remove the metal scats prior to the high voltage pulse treatment.

(23) The advantages of the invention are: Preconcentration of ore grade to enhance metal recovery in flotation or downstream separation; Increased circuit capacity since 20 to 30% of the ore feed can be rejected from the process by the invention; Reduce the tonnage and therefore the costs of ore haulage by using the invention underground or in pit where the ore is mined and rejecting waste at an early stage; Increase viable ore resources by using the invention to reject waste and reduce the mining cut-off grade. Particles in the screen undersize product which have been broken by the HVP discharge are weakened (compared to the feed) due to the generation of cracks/microcracks by the high voltage pulse energy. This will reduce the energy consumption in the downstream comminution processes. The screen undersize product which has been broken by the high voltage pulse discharge contains particles with better liberation of the high conductivity/permittivity minerals than achieved when mechanically breaking the particles. This is caused by preferential breakage around boundaries of different minerals when broken by high voltage pulses. This will enable better concentrate grades and recovery in the downstream separation processes. This improved liberation is also observed in particles after additional mechanical breakage.

(24) It will of course be realised that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to those of skill in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.