Field of the Invention

The present invention relates to an apparatus and a method for treatment of mined material with electromagnetic radiation, and relates particularly, although not

exclusively, to an apparatus and a method for treatment of mined materials with microwave radiation.

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 also understood herein to include (a) run-of-mine material and (b) run-of-mine material that has been subjected to at least primary crushing or similar size reduction after the material has been mined and prior to being sorted.

Further, the term "mined" material includes mined material that is in stockpiles.

The present invention also relates to recovering valuable material from mined material arid relates particularly, although not exclusively, to treating mined material at high throughputs.

Background of the Invention

It has recently been proposed to treat mined material with high. intensity microwave radiation. to cause formation of cracks in fragments of the mined material. The fragments may include gangue and valuable material (such as copper or iron containing minerals) and the exposure of "the fragments to high power-density electric fields associated with high intensity microwave radiatdon causes

preferential heating and resultant thermal expansion of some of the components of the fragments, which results in formation of micro- and macro-cracks. Such cracks improve for example access for leach solutions. The formation of the cracks is directly related to the value and rate of development of a temperature differential that is created during the application of the high intensity microwave radiation .

Further, it has recently been proposed to use microwave heat treatments for sorting purposes.

Gravity-fed chutes or conveyor system are used to direct the fragments of the mined material through microwave radiation treatment regions in which the fragments are exposed to the microwave radiation. Both conveyor belts and chutes suffer from a disadvantage in that they are suitable for moving large amounts of the fragments through the microwave treatment regions, but it is difficult to control a distribution of the fragments within the .

microwave treatment region. Further, it is difficult to control the residence time and density of the fragments, which makes it difficult to control a distribution of microwave energy within the treatment region. Summary of the Invention

The present invention provides in a first aspect an apparatus for treatment of mined material, the apparatus comprising:

at least one source for generating electromagnetic radiation;

a treatment region for exposing fragments of the mined material to the electromagnetic radiation; and

a transport arrangement for moving the fragments of the mined material, the transport arrangement comprising opposite wall portions that are arranged _^ to move when the fragments of the mined material are moved by the transport arrangement;

wherein the apparatus is arranged such that at least some fragments of the mined material are bridged across a space defined between the opposite wall portions and are substantially stationary relative to the opposite wall portions such that fragments of the mined material move through at least a portion of the treatment region in a controlled manner.

- The present invention provides in a second aspect an

apparatus for treatment of mined material, the apparatus comprising:

at least one source for generating electromagnetic radiation;

a treatment region for exposing fragments of the mined material to the electromagnetic radiation; and

a transport arrangement for moving the fragments of the mined material, the transport arrangement comprising opposite wall portions that are arranged to move when the fragments of the mined material are moved by the transport arrangement;

wherein the apparatus is arranged such that

fragments of the mined material are confined by material lock-up and are substantially stationary relative to the opposite wall portions such that fragments of the mined material are moved through at least a portion of the treatment region in a controller manner. The following introduces features of the apparatus in accordance with embodiments of the first or second aspect of the present invention.

The electromagnetic radiation may be suitable to cause structural alternations of fragments of the mined

material. Alternatively, the microwave radiation may be suitable to cause changes in temperature, of the fragments of the mined material suitable for sorting purposes. The term "structural alternations" is understood herein to mean any type of structural alternations, such as

formation of micro-cracks , macro-cracks and and/or

fragmentation. The apparatus may be arranged such that the fragments of the mined material move in direction that has a downward component, or in a downward direction.

In a first embodiment _. of .the present invention the

transport arrangement comprises the treatment region. In this embodiment the apparatus may be arranged such that the fragments of the mined material are exposed to the electromagnetic radiation at a time when the fragments of the mined material are substantially stationary relative to the opposite wall portions of the transport

arrangement.

In an alternative second embodiment of the present

invention the treatment region is positioned above the transport arrangement. In this embodiment the apparatus may be arranged such that throughput of further fragments of the mined material through the treatment region is limited by the fragments that are substantially stationary relative to the opposite wall portions the transport arrangement.

In one embodiment the opposite wall portions are

substantially parallel to each other.

The apparatus may also comprise a structure that is arranged such that propagation of the electromagnetic radiation from the treatment region through a portion of the apparatus is reduced. For example, the, portion of the apparatus may be a conduit that is arranged to guide the fragments of the mined material towards or away from the treatment region. The conduit may comprise the structure and in one specific embodiment the structure is arranged such that at least a portion of electromagnetic radiation that is propagating from the treatment region into the conduit is reflected back. In this embodiment the

structure may be arranged such that an electric field intensity associated with the electromagnetic radiation decreases at a rate of at least 15, 20, 25, 30, 35, 40, 45 or 50 dB/m in a direction from a radiation inlet of the apparatus into the conduit and/or such that. at least portions of at least some fragments of the mined material entering the treatment region absorb electromagnetic power at a rate of at least 10, 20, 30, 40, 50, 60, 70, 80, 90 or even 100 dB/m. In one embodiment the conduit is provided at least in part by an inner liner that comprises a suitable dielectric material that is substantially transmissive for the electromagnetic radiation. Any dielectric material has. a relative dielectric

permittivity e*=8'-js" that has a real part ε' and an imaginary part j (ε") . The suitable dielectric material may have a relative dielectric permittivity that has a real part ε' in the range of 0.5 - 50, 1 - 20 or 5 - 10 and an imaginary part ε" in the range of 0.0001 - 0.1. For example, the suitable dielectric material may be Al ₂ 0 ₃ , ALN, ALB or quartz.

The structure may have dielectric properties that change sequentially along a portion of the structure. The

structure may comprise a succession of alternating first and second zones extending along a length of the structure and being arranged such that electromagnetic radiation, when passing into the structure, experiences a dielectric property in the first zones that is different to that in the second zones. Further, the apparatus may comprise a further conduit through which the fragments of the mined material are directed after exiting the transport

arrangement and the further conduit may also comprise the above-defined structure that is arranged such that

propagation of the electromagnetic radiation from the treatment region through a portion of the apparatus is reduced.

The apparatus may be arranged such that the fragments of the mined material are surrounded by wall portions in a plane that is oriented transversal to the direction of movement of the fragments of the mined material when the fragments of the mined material are moved through the treatment region. In one specific embodiment the transport arrangement is provided in the form a posimetric feeder.

However, it will be appreciated by a person skilled in the art that the transport arrangement may alternatively be provided in another suitable form. In one specific embodiment the at least one source is arranged to generate microwave radiation. The microwave radiation may have any suitable wavelength in the range of 1 - 100 MHz, 100 - 200 MHz, 200 - 300 MHz, 300 MHz - 500 MHz, 500 MHz - 30 GHz or 600 MHz - 3 GHz, for example 2450 MHz, 350 MHz or 915 MHz.

The apparatus may be arranged such that the microwave radiation causes heating of at least portions of at least some fragments of the mined material in the treatment region and an associated power-density in, the heated phase of the fragments of the mined material is at least 1 x 10 ⁹ W/cm ³ , 1 x 10 ¹⁰ /cm ³ , or at least 1 x 10 ¹¹ W/cm ³ .

The apparatus may also comprise a window that is at least partially formed form a material that is substantially transmissive for the electromagnetic radiation and through which in use the electromagnetic radiation is directed to the treatment region. The window may form a wall portion of the apparatus and may be formed from a material that has dielectric properties similar to those of the

fragments of the mined material. In one example the window comprises the above-described suitable dielectric

material.

The present invention provides in a third aspect an apparatus for treatment of mined material, the apparatus comprising:

at least one source for generating electromagnetic radiation;

a treatment region for exposing the mined material to the electromagnetic radiation; and

a posimetric feeder that is arranged to move the fragments of the mined material through the treatment region..

In a first embodiment the posimetric feeder comprises the treatment region. In this embodiment the apparatus may be arranged such that fragments of the mined material are exposed to the electromagnetic radiation when the

fragments are substantially stationary relative to a portion of the posimetric feeder. In a second embodiment the treatment region is positioned above the posimetric feeder and the apparatus is arranged such that in use the fragments of the mined material are exposed to the electromagnetic radiation before reaching the posimetric feeder. In this case the apparatus may be arranged such that throughput of further fragments of the mined material through the treatment region is limited by the posimetric feeder. The electromagnetic radiation may be microwave radiation that may be suitable to cause structural alternations of the fragments of the mined material. Alternatively, the microwave radiation may be suitable to cause changes in temperature of the fragments of the mined material suitable for sorting purposes.

The present invention provides in a fourth aspect a method for treatment of mined material, the method comprising the steps of:

moving fragments of the mined material in a manner such that at least some fragments of the mined material are bridged across a space defined between wall portions of an arrangement for moving the fragments of the mined material;

generating electromagnetic radiation; and

exposing the fragments mined material in a treatment region to the electromagnetic radiation.

The method may comprise moving the fragments of the mined material in direction that has a downward component, or in a downward direction.

In a first embodiment the method comprises exposing the fragments of mined material to the electromagnetic

radiation in the treatment region at a time when at least some of the fragments of the mined material are bridged across a space defined between wall portions of the arrangement for moving the fragments of the mined

material .

In an alternative second embodiment the method comprises exposing further fragments of the mined material before the further fragments reach the transport arrangement. In this embodiment the method may comprise limiting the throughput of the further .fragments of the mined material using an arrangement for moving the fragments of the mined material.

The electromagnetic radiation may be microwave radiation and may be suitable to cause structural alternations of the fragments of the mined material. The microwave

radiation may have any suitable frequency, such as a wavelength in the range of 1 - 100 MHz, 100 - 200 MHz, 200

- 300 MHz, 300 MHz - 300 GHz, 500 MHz - 500 MHz or 600 MHz

- 3 GHz, for example 2450 MHz, 350 MHz or 915 MHz. The method may be conducted such that the microwave radiation causes heating of the particulate material in the

treatment region and an associated power-density in the heated phase of at least some of the fragments of the mined material is at least 1 x 10 ⁹ W/cm ³ , 1 x 10 ¹⁰ /cm ³ , or at least 1 x 10 ¹¹ W/cm ³ .

The throughput of the mined, material may be at least 100, 250, 500 or 1000 tonnes per hour.

The method may also comprise subsequent processing the treated fragments, such as hydrometallurgical processing and leaching.

The invention will be more fully understood from the following description of specific embodiments of the invention. The description is provided with reference to the accompanying drawings. Brief Description of the Drawings

Figures 1 and 2 are schematic representations of apparatus for treatment of mined material in accordance with

specific embodiments of the present invention;

Figure 3 is a flow chart of a method of treating a mined material in accordance with a specific embodiment of the present invention; and

-

Figures 3 to 9 are schematic representations of apparatus for treatment of mined material in accordance with

specific embodiments of the present invention.

Detailed Description of Specific Embodiments

Referring initially to Figures 1 and 2, an apparatus for treatment of mined material in accordance with a specific embodiments of the present invention is now described.

Figure 1 shows an apparatus 100 in accordance with a first embodiment of the present invention. The apparatus 100 comprises a crusher 102 that is arranged to receive mined material. The mined material may comprise an ore, such as a copper, nickel or iron containing ore or another

suitable ore. The crusher 102. is in this embodiment arranged to crush the mined material such that fragments of the mined material have a particle size of the order of 10 to 75 cm.

The fragments of the mined material are then directed by conveyor belt 104 into a chute 106. The chute 106 is a conduit that surrounds the falling fragments of the mined material and. provides a vertical passage through which the fragments of the mined material fall by gravity. The fragments are then directed into an arrangement for moving the fragments of the mined material and in this embodiment the arrangement is provided in the form of a posimetric feeder 108. However, a person skilled in the art will appreciate that the arrangement for moving the fragments of the mined material may alternatively be provided in another suitable ^' form.

The posimetric feeder 108 comprises a microwave treatment region 110 in which the fragment of the mined material are exposed to microwave radiation. Further, the apparatus 100 comprises a microwave generator 112 that is coupled to the posimetric feeder 108 at the treatment region 110. Chute portion 114 directs the fragments of the mined material away from the posimetric feeder 108 for further

processing. The microwave generator 112 directs the microwave radiation to the microwave treatment region 110 ^■ via a window 116 that forms a wall portion of the

posimetric feeder 108 and is largely transparent for microwave radiation. In one variation the microwave generator 112 generates microwave radiation such that in the microwave absorbent phase of the fragments of the mined material a resulting power-density is in the region of 10 ⁶ -10 ¹⁴ /m ³ . The power density is sufficiently high such that portions of

fragments of the mined material will experience an

increase in temperature. Different types of materials have different receptiveness for microwave radiation and

different thermal expansion coefficients. For example, minerals, silicates or similar materials that form rock have a thermal expansion coefficient that is different to that of copper or iron containing minerals. Consequently, when for example copper-containing minerals are surrounded by gangue and are exposed to such treatment, micro-cracks or macro-cracks form. The formation of the cracks

facilitates materials separation, for example by

facilitating access for leach solutions. The arrangement for moving the fragments of the mined ^■ material is in this embodiment provided in the form of the posimetric feeder 108 (which will be described in further detail below) that is arranged such that the fragments of the mined material bridge across moving wall portions of the posimetric feeder 108 when the particles are moved through the treatment region 110, which results in a relative uniform density distribution throughout the treatment region 110 and corresponding relative uniform dielectric properties of the mined material in the

treatment region. Because of the relatively uniform dielectric properties and the shape of a treatment chamber of the posimetric feeder (108), an electric field

associated with the microwave radiation is relatively uniform within the treatment region 110 and consequently the microwave radiation treatment of the fragments of the mined material is relatively uniform in the treatment region .

The microwave radiation to which the mined material is exposed in the apparatus 100 is continuous (but may in a variation of the described embodiment also be pulsed) and the apparatus 100 is arranged such that the exposure time of the fragments is of the order of 1 second or less. The power ^' density is of the order of 1 x 10 ⁷ W/m ³ - 1 x 10 ¹³ W/m ³ in the heated phase within the fragments of the mined material .

5 Figure 2 shows an apparatus 200 in accordance with a

second specific embodiment of the present invention. The apparatus 200 comprises various components that are identical to those of the apparatus 100 and like reference numerals are used for like components. However, the

10 apparatus 200 comprises a microwave treatment region 210 with microwave generator 212 that are positioned above a posimetric feeder 108. As mentioned above, the posimetric feeder 108 results in a relative uniform density- distribution within a portion of the posimetric feeder

15 108. The apparatus 200 is in this embodiment arranged such that the posimetric feeder 108 limits throughput through the treatment region 210 in a manner such that also in the region above the posimetric feeder 108 (in the treatment region 210) the fragments have a relatively uniform

' -20 density distribution and consequently an electric field associated with the microwave radiation is relatively uniform.

Figure 3 illustrates a method 300 of treating mined

25 . material using the apparatus 100 or 200. Step 302 moves fragments of the mined -material using the arrangement for moving the fragments and in a manner such that the

fragments of the mined material are bridged across a space defined between wall portions of the arrangement. Step 304 30 generates electromagnetic radiation and step 306 exposes the mined material in a treatment region to the

electromagnetic radiation. Referring now to Figures 4 to 9 apparatus for treatment of mined material in accordance with further embodiments of the present invention is now described. Figure 4 shows - the apparatus 400 that comprises a

posimetric feeder 402 to which a microwave radiation generator 404 is coupled. Fragments of the mined material 406 are fed into the posimetric feeder 402 using a

suitable chute and moved through microwave treatment region 408. In this embodiment the posimetric feeder 402 comprises the treatment region 408.

Figure 5 shows an alternative embodiment in which

apparatus 500 also comprises the posimetric feeder 402, but the microwave treatment region 508 is positioned above the posimetric feeder 402 at a chute portion that has a window that is formed from a dielectric material that is transparent for the microwave radiation. Any dielectric material has a relative dielectric

permittivity s*=e'-jE" that has a real part ε' and an imaginary part j (ε") . The dielectric material of the window has a real part ε' in the range of 0.5 - 50, 1 - 20 or 5 - 10 and an imaginary part ε" in . the range of 0.0001 - 0.1. For example, the material of the window may be AI2O3, ALN, ALB or quartz.

The apparatus 500 is in this embodiment operated such that the posimetric feeder 402 limits throughput in a manner such that a relatively uniform density distribution of the fragments of the mined material is generated in the treatment area 508. In this variation the apparatus 500 is used for sorting and the microwave source 504 is adjusted such that the temperature of the fragments is increased as a function of properties of the fragments without inducing mircocracks. The apparatus 500 comprises a sorting

arrangement 550 that has a sorting component 552 that identifies and separates "hot" particles from "cold" particles using a thermal detector (for example in the form of an infrared camera) . The detector is calibrated to determine whether a given particle is "hot" or "cold". This information is used to operate ejectors 554

selectively to emit a jet of gas (typically compressed air) into the path of "hot" particles 556 so that they are deflected onto an alternate trajectory, "cold" particles 558 continue on their original trajectory. As a result, "hot" particles and "cold" particles are separated into two respective streams.

Figure 6 shows a perspective view of an exemplary

posimetric feeder .600 that may replace the posimetric feeder 402 shown in Figures 4 and 5. The posimetric feeder 600 has a window 602 that is formed from a

microwave transparent material and forms a wall portion of the posimetric feeder 600. The microwave generator 404 (shown in Figure 4) has a cavity that is positioned such that generated microwave radiation is directed into the treatment regions 408 through the window.

The posimetric feeders 402, 600 comprise drives 410 and 604, respectively, which are arranged to rotate an inner drum (not shown) to which pairs of parallel disc-shaped members 412 and 606 are attached such that a reel is formed. ^' In use, the posimetric feeder 402, 600 rotates the reel and thereby moves the fragments of the mined material 406 through the posimetric feeder 402, 600 in a well defined manner. Specifically, the pairs of discshaped members 412 and 606 of each reel are arranged such that the fragments of the mined material bridge across a space that is defined between the two ^' disc-shaped members of each reel and are substantially stationary relative to respective pairs 412 and 606 of disc-shaped members.

Further, fragments of the mined material are locked in position by confinement between a respective pair of discshaped members in one dimension and the inner drum of the posimetric feeder and an outer cylindrical wall portion

(which includes the microwave transparent window 602) in a transversal dimension. After microwave treatment in the treatment region 408 and 508 the fragments of the mined material are then directed away for further processing.

The posimetric feeders 402 and 600 are relatively small devices, which is advantageous for confining the microwave radiation to the treatment region and thereby increasing an efficiency of the microwave radiation treatment.

Figure 7 illustrates an apparatus 700 that is related to the apparatus 500 shown in Figure 5, but in this case the apparatus 700 is arranged for treatment of mined material with microwave radiation in a manner such that micro- cracks are introduced. The apparatus 700 comprises a chute portion 702 for feeding by gravity. The apparatus 700 also comprises a posimetrc feeder 704, which may be provided in the form of the above-described posimetric feeder 600. A microwave generator 708 is coupled to the chute portion 702 in a manner such that a treatment region 706 for exposing the. mined material to the microwave radiation is located above the posimetric feeder 704. In this

embodiment the apparatus 700 is operated such that the 704 posiraetric feeder limits throughput through the treatment region 706 in a manner such that fragments of the mined material have a relatively uniform density distribution in the treatment region 706.

Figure 8 shows an apparatus for treatment of mined

material in accordance with a further embodiment of the present invention. The apparatus 800 comprises the

posimetric feeder 402 and the microwave generator 404. Further, the apparatus 800 also comprises chute portion 802 through which the fragments of mined material are directed to the posimetric feeder 402.

The chute portion 802 comprises a structure that is arranged to reflect a portion of microwave radiation that propagates from the posimetric feeder 402 into the chute portion 802. The reflection of the microwave radiation reduces propagation of the microwave radiation through the chute portion 802 (away from the treatment region 408) and consequently reduces pre-heating of the fragments of the mined material before the fragments of the mined material will reach the treatment region 408. In this embodiment the structure is arranged such that an electric field intensity associated with the electromagnetic radiation decreases at a rate of at least 15, 20, 25, 30, 35, 40, 45 or 50 dB/m in a direction from a radiation inlet of the apparatus into the conduit or such that at least portions of at least some of the fragments of the mined material entering the treatment region experience an increase in power density associated with the microwave radiation at a rate of at least 30, 40, 50, or 60, dB/m.

The structure of the chute portion 802 comprises a plurality of circular corrugations 804 that together are positioned to form a corrugated choke and reflect the microwave radiation back into the posimetric feeder 402. In this embodiment, the chute portion 802 comprises 8 of such corrugations 804, but may alternatively also comprise any other suitable number of corrugations. The corrugated choke of the chute portion 802 is a tubular arrangement that is formed form a metallic material and has a largely uniform wall thickness and an undulating inner and outer diameter. A cylindrical liner formed form the above- · described dielectric material that is transparent for the microwave radiation and is positioned within the

corrugated choke. Further, the chute portion 802 has an outer metallic shell that is not shown.

The apparatus 802 also comprises chute portion' ^{^} 806 through which the fragments of the mined material are directed away from the posimetric feeder for further procession. The chute portion 806 also comprises a structure that is arranged to reflect a portion of microwave radiation that propagates from the posimetric feeder 402 into the chute portion 806 and that structure comprises 8 corrugations 804 and is analogous to the above-described structure of the chute portion 802. The corrugated structure of the chute portion 806 reduces leakage of microwave radiation, which relates to energy and safety advantages.

Figure 9 shows an apparatus 900 in accordance with an alternative embodiment of the present invention. The apparatus 900 comprises various components that are identical to those of the apparatus 800 and like reference numerals are used for like components. However, the apparatus 900 comprises a microwave treatment region 908 and a- microwave generator 904 that are positioned above a ^■ posimetric feeder 402. As mentioned above, the posimetric feeder 402 results in a relative uniform density

distribution within a portion of the posimetric feeder 402. The apparatus 900 is in this, embodiment arranged such that the posimetric feeder 402 limits throughput in a manner such that also in the region above the posimetric feeder 402 (in the treatment region 908) the fragments have a relatively uniform density distribution. Similar to the apparatus 500 illustrated with reference to Figure 5, the apparatus 100, 200, 400, 700, 800, and 900 may alternatively not be arranged to expose the fragments of the mined material intensities of microwave radiation that are sufficiently high such that cracks are formed in the fragments, but may be arranged to expose the fragments to lower intensities of the radiation and at longer periods of time to increase a temperature of valuable components of the fragments. In this case fragments may be sorted in a manner similar to that described above and with reference to Figure 5.

It is to be appreciated that various variations of the described embodiments are possible. For example, the apparatus for treatment of .mined material may be arranged to generate microwave radiation having any suitable freguency. Further, the apparatus may not necessarily comprise a posimetric feeder.