TECHNICAL FIELD

The present invention relates to a method and an apparatus for deflecting selected fragments of mined material from a path of movement of fragments to facilitate separating these selected fragments from other fragments moving along the path of movement.

The present invention also relates to a method and an apparatus for sorting mined material typically at high throughputs for subsequent processing to recover valuable material that includes the method and an apparatus for deflecting selected fragments of mined material.

The term "mined" material is understood herein to include metalliferous material and non-metalliferous material. Iron-containing and copper-containing ores are examples of metalliferous material. Coal is an example of a non-metalliferous material. The term "mined" material is understood herein to include, but is not limited to (a) run-of-mine material and (b) run-of-mine material that has been subjected to size reduction, for example primary crushing or similar size reduction and optionally other crushing and grinding steps, after the material has been mined and prior to being sorted and (c) run-of-mine material that has been subjected to size classification without size reduction after the material has been mined and prior to being sorted. The "mined material" includes mined material that is in stockpiles.

The present invention also relates to a method and an apparatus for recovering valuable material, such as valuable metals, from mined material that has been sorted as described above.

BACKGROUND ART

Automated systems for sorting mined material known to the applicant are limited to low throughput systems, typically systems processing less than 100 t/h. There is a need for automated mined material sorting systems that are capable of processing larger throughputs of 500-1000 t/h in order to realise the economies of scale required for many applications in the mining industry such as sorting low grade ore having fragment sizes greater than 10 mm. There are a number of engineering reasons for known automated mined material sorting systems being limited to low throughput systems.

One reason is related to known apparatus for physically separating selected fragments from other fragments of mined material. The general approach used in known fragment separation apparatus is to direct short blasts of high pressure compressed air from an injection nozzle towards a target zone through which a stream of fragments move in an established trajectory to deflect a selected fragment in the target zone at that time from its trajectory. Air is typically used as an ejection fluid because (a) fluid control valves in automated mined material sorting systems have to be able to open and close in short time periods, typically 5 milliseconds, and the fastest hydraulic valves currently available can only act at speeds of 10 milliseconds, and this would therefore prohibit the use of a hydraulic fluid such as water and (b) the valves currently used are spring-less return solenoid valves which are very sensitive to moisture and this therefore prohibits the use of air already containing water droplets. Because of its nature, compressed air expands immediately upon discharge from an injection nozzle, and this expansion increases the size and dilutes the intensity and velocity of a pressure front created by the compressed air. This expansion of compressed air makes it necessary for the target zone and hence the separation between successive fragments in the stream of fragments to be comparatively large in order to ensure that a selected fragment is the only fragment that is deflected by a blast of compressed air. More specifically, because of the expansion of a blast of compressed air, it is necessary to have a larger separation between successive fragments in a stream of fragments to ensure selective separation of individual selected fragments than would be necessary if it was possible to direct a more confined blast of compressed air at the stream of fragments. This separation between fragments is a factor that has an impact on the maximum throughput for the system. Furthermore, the expansion of a blast of compressed air means that there is a loss of pressure with distance from an injection nozzle. This has an impact on the maximum mass of a fragment that can be deflected by the blast of compressed air and is another factor that has an impact on the maximum throughput for the system. In addition, the cost involved in providing an air plant that is sufficiently large to deliver the volumes of compressed air that are required for high throughput sorting systems has an impact on the commercial viability of the system. In addtion, air has a relatively low density relative to the ore fragments to be separated. As per the classical definition of momentum being a product of mass and velocity (p=mv), the air needs considerable velocity to have enough momentum to deflect an ore fragment.

The above references to the background art do not constitute an admission that the art forms a part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the apparatus and method as disclosed herein.

SUMMARY OF THE DISCLOSURE

The applicant is developing an automated method and apparatus for sorting mined material.

In general terms, the method of sorting mined material being developed by the applicant includes the following steps:

(a) exposing fragments of mined material to electromagnetic radiation, such as microwave radiation or radio frequency radiation;

(b) detecting fragments of material after the material has been exposed to electromagnetic radiation;

(c) using detected data and assessing fragments on the basis of composition (including inferred grade) or texture or another characteristic of the fragments; and

(d) physically separating fragments based on the assessment in step (c). The purpose of exposing mined material to electromagnetic radiation is to cause a change in the mined material that provides information on characteristics of the mined material that is helpful for sorting and ultimately downstream processing of fragments of the mined material and that can be detected by one or more than one sensor. The information may include any one or more of the characteristics of composition (including grade of a valuable metal), mineralogy, hardness, porosity, color, structural integrity, dielectric properties, and texture of the mined material.

The invention is relevant to the automated method and apparatus for sorting mined material being developed by the applicant.

In general terms, the invention relates to any automated method and apparatus for sorting mined material that exhibit active (i.e. induced) or passive differences in characteristics of the mined material that allow differentiation between more and less valuable fragments of the mined material.

More specifically, the invention is relevant generally to any automated method and apparatus for sorting mined material that operates with active or passive energy sources as a basis to determine information relating to fragments of mined material to use as a basis for sorting the mined material. The term "active" in this context is understood to mean systems using energy sources to change fragments, for example heat fragments, as a function of the characteristics of the material in the fragments so that differences in response can be used as a basis for sorting fragments. The above- described automated method and apparatus for sorting mined material being developed by the applicant is an example of an active energy system. The term "passive" in this context is understood to mean systems in which fragments are exposed to energy sources that do not change the fragments but make it possible to determine differences between fragments. Sorting based on differences in color or surface texture of fragments are examples of such a system.

According to the present invention there is provided a method of deflecting a selected fragment of mined material from a path of movement of fragments to facilitate separating the selected fragment from other fragments moving along the path, the method including selectively actuating a delivery assembly and releasing a packet of steam directed at a target zone, with the packet of steam forming one or more water droplets that impact the selected fragment as it moves through the target zone and deflects the selected fragment from the path of movement.

The present invention is based on a realisation that a packet of steam, typically pressurised saturated or superheated steam, that condenses upon release from a delivery apparatus into the ambient atmosphere, can create a cluster of water droplets travelling with sufficient velocity and density and resultant momentum to deflect a selected fragment in a target zone in a path of movement of fragments.

In contrast to the compressed air option described above, the water droplets resulting from the phase change from steam to water are in a much smaller volume, thus maintaining a higher density and enabling greater target selectivity and therefore making it possible to have smaller separation between successive fragments in a stream of fragments and hence a smaller target zone. Another advantage of the steam/water droplet-based method of the invention over the compressed air option described above is velocity of water droplets.

Compressing air in the volumes needed for a full scale commercial mine-based sorter (for example a 1,000 t/h sorter operating at 30% blast will require around 9t/h of compressed at 700kPa.a) is capital and operating cost intensive. The problem may be exacerbated by lower pressures found at altitude (where mineral deposits are often found).

The path of movement of fragments may be a free fall or a flight trajectory established upstream of the delivery system.

The free fall or the flight trajectory may be established by launching the fragments.

The steam may be pressurised steam. The pressure may be any suitable pressure. The steam may be saturated steam.

The steam may be superheated steam.

The method may include selectively actuating the delivery assembly to deflect the selected fragment in response to a control signal from a fragment detection and assessment assembly that identifies the fragment as a selected fragment that is upstream of the delivery assembly in terms of the direction of movement of fragments.

The selection may be based on any suitable criteria.

For example, the selection criteria may be composition (including grade that is determined directly or inferred) of the fragment. By way of further example, the selected criteria may be color of fragments.

The method may include selectively actuating the delivery assembly to deflect a plurality of selected fragments from the stream of fragments as fragments move through the target zone.

The method may include selectively actuating the delivery assembly to deflect selected fragments from each of a plurality of separate streams of fragments as fragments move through the target zone of each stream of fragments

The method may include selectively actuating the delivery assembly to deflect a plurality of selected fragments from a plurality of streams of fragments moving along trajectories that include a plurality of the target zones. The method may include processing mined material at a throughput greater than

100 t/h.

The throughput may be at least 200 t/h.

The throughput may be at least 500 t/h.

According to the present invention there is also provided an apparatus for deflecting selected fragments of mined material from a path of movement of the fragments to facilitate separating the selected fragment from other fragments moving along the path of movement, the apparatus including:

(a) a steam generation system;

(b) a delivery assembly in fluid communication with the steam generation system; the delivery assembly operable to release a packet of steam directed at a target zone through which the selected fragment travels; the packet of steam forming one or more water droplets to impact the selected fragment to deflect the selected fragment from the path of movement of the other fragments.

The discharge nozzles may be configured to form a narrow stream or cluster of water droplets.

According to the present invention there is also provided a method of sorting mined material including the following steps:

(a) detecting information on a characteristic of fragments of mined material,

(b) using detected data and assessing fragments on the basis of the characteristic, and

(c) physically separating fragments based on the assessment in step (b) in accordance with the method of separating selected fragments of mined material from a path of movement of fragments described above.

The information may include any one or more of the characteristics of composition (including grade of a valuable metal), mineralogy, hardness, porosity, color, structural integrity, dielectric properties, and texture of the mined material.

Step (a) may include detecting information on the characteristic of fragments using an active or a passive energy source as described above.

According to the present invention there is also provided a method of sorting mined material including the following steps:

(a) exposing fragments of mined material to electromagnetic radiation, (b) detecting fragments of material after the material has been exposed to electromagnetic radiation;

(c) using detected data and assessing fragments on the basis of composition (including grade) or texture or another characteristic of the fragments, and

(d) physically separating fragments based on the assessment in step (c) in accordance with the method of separating selected fragments of mined material from a path of movement of fragments described above.

According to the present invention there is also provided an apparatus for sorting a mined material, including:

(a) a treatment assembly for exposing fragments of mined material to an active or a passive energy source as described above;

(b) a fragment detection and assessment assembly including (i) plurality of sensors for detecting the response of each fragment to energy from the active or passive energy sources and (ii) a processor for analysing the data for each fragment and classifying the fragment for sorting and/or downstream processing of the fragment; and

(c) the separation apparatus described above.

According to the present invention there is also provided an apparatus for sorting a mined material, including:

(a) an electromagnetic radiation treatment assembly for exposing fragments of mined material on a particle by particle basis to an active energy source in the form of electromagnetic radiation;

(b) a fragment detection and assessment assembly including (i) plurality of sensors for detecting the response of each fragment to electromagnetic radiation and (ii) a processor for analysing the data for each fragment and classifying the fragment for sorting and/or downstream processing of the fragment; and

(c) the separation apparatus described above.

The separator assembly may include the delivery assembly described above and a distribution assembly for distributing fragments into a plurality of trajectories.

According to the present invention there is also provided a method and an apparatus for recovering valuable material, such as valuable metals, from mined material that has been sorted as described above. The mined material may be any mined material that contains valuable material, such as valuable metals. Examples of valuable materials are valuable metals in minerals such as minerals that comprise metal oxides or metal sulphides. Specific examples of valuable materials that contain metal oxides are iron ores and nickel laterite ores. Specific examples of valuable materials that contain metal sulphides are copper-containing ores. Other examples of valuable materials are salt and coal.

Particular, although not exclusive, areas of interest to the applicant are mined material in the form of (a) ores that include copper-containing minerals such as chalcopyrite, in sulphide forms and (b) iron ore.

The present invention is particularly, although not exclusively, applicable to sorting low grade mined material.

The term "low" grade is understood herein to mean that the economic value of the valuable material, such as a metal, in the mined material is only marginally greater than the costs to mine, recover and transport the valuable material to a customer.

In any given situation, the concentrations that are regarded as "low" grade will depend on the economic value of the valuable material and the mining and other costs to recover the valuable material from the mined material at a particular point in time. The concentration of the valuable material may be relatively high and still be regarded as "low" grade. This is the case with iron ores.

In the case of valuable material in the form of copper sulphide minerals, currently "low" grade ores are run-of-mine ores containing less than 1.0 % by weight, typically less than 0.6 wt.%, copper in the ores. Sorting ores having such low concentrations of copper from barren particles is a challenging task from a technical viewpoint, particularly in situations where there is a need to sort very large amounts of ore, typically at least 10,000 tonnes per hour, and where the barren fragments represent a smaller proportion of the ore than the ore that contains economically recoverable copper.

The term "barren" fragments when used in the context of copper-containing ores are understood herein to mean particles with no copper or very small amounts of copper that can not be recovered economically from the fragments.

The term "barren" fragments when used in a more general sense in the context of valuable materials is understood herein to mean particles with no valuable material or amounts of valuable material that can not be recovered economically from the fragments.

The term "fragment" is understood herein to mean any suitable size of mined material having regard to materials handling and processing capabilities of the apparatus used to carry out the method and issues associated with detecting sufficient information to make an accurate assessment of the mined material in the particle. It is also noted that the term "fragment" as used herein may be understood by some persons skilled in the art to be better described as "particles". The intention is to use both terms as synonyms.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the apparatus and method as set forth in the Summary, a specific embodiment will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a perspective view in very schematic form of one embodiment of an apparatus for sorting mined material in accordance with the invention which includes one embodiment of an apparatus for separating selected fragments from a stream of fragments in accordance with the invention;

Figure 2 shows a side view of the apparatus shown in Figure 1; and

Figure 3 is a diagram that illustrates in general terms the embodiment of the apparatus for separating selected fragments in accordance with the invention and a known compressed air-based method of deflecting fragments of mined material.

DESCRIPTION OF EMBODIMENTS

The embodiments of the invention shown in the Figures are described in the context of a method of recovering a valuable metal in the form of copper from low grade copper-containing ores in which the copper is present in copper-containing minerals such as chalcopyrite and the ores also contain non-valuable gangue.

The objective of the embodiment of the sorting method and apparatus of the invention is to identify fragments of mined material containing amounts of copper- containing minerals above a certain grade to separate these fragments from the other fragments, and to process the copper-containing fragments using the most effective and viable option to recover copper from the fragments.

The objective of the embodiment of the fragment separation method and apparatus of the invention is to separate the selected fragments. This embodiment is described as being part of the embodiment of the sorting method and apparatus. The invention is not so limited and the embodiment could be used as part of other embodiments of the sorting method and apparatus.

It is noted that, whilst the following description does not focus on the downstream processing options, these options are any suitable options including flotation, gravity separation, smelting and leaching of selected fragments.

It is also noted that the invention is not confined to copper-containing ores and to copper as the valuable material to be recovered. In general terms, the embodiment of the sorting method and apparatus of the invention provides a method of sorting any mined materials which exhibit characteristics (which may also be described as properties) that enable separation of high and low grade fragments.

It is also noted that the invention is not confined to using a grade threshold as the sole basis for sorting the fragments and the invention extends to considering other characteristics (i.e. properties) that are indicators of the suitability of fragments for downstream recovery processes.

The fragment separation method and apparatus of the invention is based on a realisation that steam, typically pressurised steam, that forms water droplets as it discharges from a delivery assembly is an effective option to provide the important requirements of velocity and density and momentum to deflect a selected fragment from an established trajectory as the fragment moves through a target zone.

In the embodiment of the separation method and apparatus of the invention shown in the Figures, a "packet" of pressurised steam (saturated or superheated) is discharged from a delivery assembly. The discharge of the steam packet is timed to cause deflection of a selected fragment from an established trajectory as that fragment moves through a target zone. The steam packet condenses immediately upon release into the ambient atmosphere and creates a cluster of water droplets travelling at high velocity towards the selected fragment as it travels through the target zone. The momentum of the water droplets is such that collision of the water droplets with the fragment causes the fragment to deflect from its traj ectory.

As is described above, in contrast to the known compressed air option, the cluster of water droplets, which is the result of a phase change from steam to water, is in a much smaller volume, thus maintaining a higher density and enabling greater target selectivity. This, in turn, makes it possible to have a smaller separation distance between successive fragments in a stream of fragments and hence a smaller target zone. Another advantage of the embodiment of the separation method and apparatus of the invention over the compressed air option described above is the velocity of water droplets. Compressing air in the volumes needed for a full scale commercial mine- based sorter (for example a 1,000 t/h sorter operating at 30% blast will require around 9t/h of compressed at 700kPa.a) is capital and operating cost intensive. The problem is exacerbated by the lower atmospheric air pressures found at high altitudes (where mineral deposits are often found). In contrast, and by way of example only, saturated steam at 200°C has a pressure of 1550 kPa.a, and can thus provides a much higher discharge velocity in operation.

Figure 3 is a diagram that illustrates in general terms the embodiment of the separation method and apparatus of the invention and the above-mentioned compressed air-based method of deflecting fragments of mined material. The upper Figure in Figure 3 illustrates the expansion of compressed air via a quick action valve 35 and a discharge nozzle 21 of a compressed air delivery assembly 23 and the consequential requirement for successive fragments 25 in a stream of fragments moving in a free fall trajectory to be separated by a distance S so that only one fragment 25 is moving through a target zone TZ at any time. The lower Figure in Figure 3 illustrates the more confined and therefore targeted cluster 27 of water droplets that is produced by discharging a packet of pressurised steam via a quick action valve 3 and a discharge nozzle 21 of a steam/water droplet delivery assembly 23 of the embodiment. As is shown in the Figure, the steam condenses immediately after discharge into the ambient atmosphere and effectively collapses into the cluster 27 of water droplets. The more focussed cluster 27 compared to the compressed air stream makes it possible to operate with a smaller distance S between successive fragments in a cluster 27 of fragments moving downwardly in a free fall trajectory while ensuring that only one fragment is moving through a target zone TZ at any time. This increases the throughput capacity of an ore sorting system.

With reference to Figures 1 and 2, in the embodiment of the sorting method and apparatus of the invention shown in these Figures, a feed material in the form of ore fragments 25 that have been crushed by a primary crusher (not shown) to a fragment size of 10-25 cm are supplied via a feed assembly 3 onto a conveyor belt 5 and the belt 5 transports the fragments 25 through a microwave radiation treatment assembly 7 that includes an exposure chamber. The feed assembly 3 and/or the belt 5 are formed and/or operated to establish a random order of the fragments 25 on the belt. The belt 5 may be any suitable width and run at any suitable speed.

The fragments 25 on the belt 5 are exposed to microwave radiation on a fragment by fragment basis as they move through the exposure chamber of the microwave radiation treatment assembly 7. The microwave radiation may be either in the form of continuous radiation or pulsed radiation. The microwave radiation may be applied at a power density below or above that which is required to induce microfractures in the fragments. In any event, the microwave frequency and microwave intensity and the fragment exposure time and the other operating parameters of the microwave treatment assembly 7 are selected having regard to the information that is required. The required information is information that is helpful in terms of classifying the particular mined material for sorting and/or downstream processing of the fragments. In any given situation, there will be particular combinations of properties, such as grade, mineralogy, hardness, color, texture, structural integrity, and porosity that will provide the necessary information to make an informed decision about the sorting and/or downstream processing of the fragments, for example, the sorting criteria to suit a particular downstream processing option.

After passing through the microwave treatment assembly 7, the fragments are detected and assessed in a fragment detection and assessment system.

More particularly, radiation from the fragments 25 is detected by high resolution, high speed infrared imagers 13 which capture thermal images of the fragments. While one thermal imager is sufficient, two or more thermal imagers may be used for full coverage of the fragment surface. In addition, one or more visible light cameras (not shown) capture visible light images of the fragments to allow determination of fragment size. From the number of detected hot spots (pixels), temperature, pattern of their distribution and their cumulative area, relative to the size of the fragments, an estimation of the grade of observed fragments can be made. This estimation may be supported and/or more mineral content may be quantified by comparison of the data with previously established relationships between microwave induced thermal properties of specifically graded and sized rock fragments.

It is noted that there may be a range of other sensors (not shown) positioned within and/or downstream of the microwave exposure chamber depending on the required information to classify the fragments for sorting and/or downstream processing options. These sensors may include any one or more than one of the following sensors: (i) near-infrared spectroscopy ("MR") sensors (for composition), (ii) optical sensors (for size and texture), (iii) acoustic wave sensors (for internal structure for leach and grind dimensions), (iv) laser induced spectroscopy ("LIBS") sensors (for composition), and (v) magnetic property sensors (for mineralogy and texture); (vi) x-ray sensors for measurement of non-sulphidic mineral and gangue components, such as iron or shale.

Images and other data collected by the thermal imagers and the visible light sensors (and any other sensors) are processed, for example, using a computer 9 equipped with image processing software. The software is designed to process the sensed data to classify the particles for sorting and/or downstream processing options and to produce control signals to actuate a downstream separator assembly. In any given situation, the software may be designed to weight different data depending on the relative importance of the properties associated with the data.

In one mode of operation the thermal analysis is based on distinguishing between fragments that are above and below a threshold temperature. The fragments can then be categorised as "hotter" and "colder" fragments. The temperature of a fragment is related to the amount of copper minerals in the fragment. Hence, fragments that have a given size range and are heated under given conditions will have a temperature increase to a temperature above a threshold temperature "x" degrees if the particles contain at least "y" wt.% copper. The threshold temperature can be selected initially based on economic factors and adjusted as those factors change. Barren particles will generally not be heated on exposure to microwave radiation to temperatures above the threshold temperature.

Once the thermal and visual light data analysis is completed by the computer 9 and each fragment is classified, the fragments are separated into two categories (or more than two categories depending on the requirements) by a fragment separation apparatus 29, generally identified by the numeral 29 in Figure 1. The separation apparatus 29 distributes the fragments 25 into a plurality of separate streams of fragments moving downwardly in free flight trajectories. The separation apparatus 29 also includes the steam/water droplet delivery assembly 23 described in relation to the lower Figure in Figure 3. The separation apparatus 29 also includes a control system that is responsive to control signals generated by the computer 9 to coordinate actuation of the delivery assembly 23 to separate selected fragments in the multiple streams of fragments. The upstream processing conditions, such as the speed of the belt 5, are selected so that successive fragments 25 in each stream are separated by the minimum distance S shown in the lower Figure in Figure 3 that ensures that only one fragment 25 is moving through each target zone TZ of the delivery assembly 23 at any time.

With particular reference to Figure 1, the separation apparatus 29 includes a chamber 33 that contains a supply of pressurised steam and a plurality of the delivery assembly 23 shown in the lower Figure of Figure 3, each assembly including a quick action valve 35 having a steam discharge nozzle 21, at spaced intervals across the width of the belt 5. The plurality of the delivery assembly 23 may also be spaced vertically. The quick action valve 35 and the delivery nozzle 21 may be of any suitable type. The apparatus may be designed to release different sized packets, i.e. varying amounts of pressurised steam, with the operating conditions being selected having regard to the size and the mass of the fragments to be separated.

In one embodiment, the primary classification criteria is the grade of the copper in fragments, with fragments above a threshold grade being separated into one collection bin 19 and fragments below the threshold grade being separated into the other bin 17. The valuable fragments in bin 19 are then processed to recover copper from the fragments. For example, the valuable fragments in the bin 19 are transferred for downstream processing including milling and flotation to form a concentrate and then processing the concentrate to recover copper. The fragments are separated by being projected from the end of the conveyor belt 5 and being deflected selectively by packets 27 of water droplets as the fragments 25 move in a free-fall trajectory from the right hand end of the belt 5 as viewed in Figure 2 and are thereby sorted into two streams that are collected in the bins 17, 19. The thermal analysis identifies the position of each of the fragments on the conveyor belt 5 and the steam discharge nozzles 21 are activated a pre-set time after a fragment 25 is analysed as a fragment to be deflected. The bins 17, 19 are in the form of elongated hoppers that have lower discharge ends that deliver material onto conveyor belts 31 and transporting the material for downstream processing or disposal, as required.

The fragments in bin 17 may become a by-product waste stream and are disposed of in a suitable manner. This may not always be the case. The fragments have lower concentrations of copper minerals and may be sufficiently valuable for recovery. In that event the colder fragments may be transferred to a suitable recovery process, such as leaching.

The above-described embodiment of the invention makes it possible to significantly increase sorting apparatus throughput compared to known sorting apparatus.

Advantages of the invention include the following advantages:

• Higher density and velocity of the water droplet packet at impact (less fluid, greater target selectivity, which equates with higher sorter unit intensity).

• As only relatively "low quality" steam is necessary it could be sourced/supplemented from a by-product from another process (for example, Combined Heat and Power (CHP) gas-fired turbine, magnetron cooling), improving the overall efficiency of the process.

• Added moisture may lower dust generation.

• Suitable steam injector nozzles may already be available.

• Injector nozzles could be custom designed to apply steam "packets" in dispersion patterns that best suited to the application.

• Lower capital and operating costs.

• More conducive to scale-up to the capacities needed by mine sorters (min l,000t/h). Whilst one specific embodiment of each of the sorting method and apparatus and the separation method and apparatus has been described, it should be appreciated that the apparatus and method may be embodied in many other forms.

The embodiments are described in the context of the use of microwave energy as the electromagnetic radiation to cause a physical change in fragments of mined material to provide information on characteristics of the mined material that makes it possible to separate fragments on the basis of the characteristics. It is noted that the invention is not confined to the use of microwave energy for this purpose and extends to the use of other types of electromagnetic radiation, such as radio frequency radiation and x-ray radiation.

In addition, it is noted that the invention is not confined to the use of electromagnetic radiation and extends to the use of any other option for providing information on characteristics of the mined material that makes it possible to separate fragments on the basis of the characteristics of the fragments. The options may include active options such as the embodiment desctribed above and passive options.

The embodiment of the sorting method and apparatus includes a conveyor belt 5 for transporting fragments though the microwave treatment assembly 7 and past thermal and visual sensors and for discharging the fragments into free flight trajectories that move the fragments past the discharge assembly. It is noted that the present invention is not limited to the use of conveyor belts 5 and extends to the use of any other suitable arrangements for transporting fragments microwave treatment assembly 7 and past thermal and visual sensors and then distributing fragments into required trajectories to move the fragments past the discharge assembly.

The embodiment of the sorting method and apparatus is described in the context of a method and an apparatus for recovering a valuable metal in the form of copper from a low grade copper-containing ore in which the copper is present in copper- containing minerals such as chalcopyrite and the ore also contains non-valuable gangue. The obj ective of the method in these embodiments is to identify fragments of mined material containing amounts of copper-containing minerals above a certain grade and to sort these fragments from the other fragments and to process the copper-containing fragments as required to recover copper from the fragments. It is noted that, whilst the following description does not focus on the downstream processing options, these options are any suitable options ranging from smelting to leaching the fragments.

It is also noted that the present invention is not confined to copper-containing ores and to copper as the valuable material to be recovered. In general terms, the present invention provides a method and apparatus of sorting any minerals which exhibit passive or active (i.e induced) differences in characteristics of minerals that allow differentiation between more and less valuable fragments of the minerals.

In the claims which follow, and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" and variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the apparatus and method as disclosed herein.