Apparatus and method for magnetizing materials

Abstract

An apparatus for inducing magnetism in a flowing stream of at least partially magnetisable dry particulate feed material for subsequent particle classification is disclosed. The dry separation stage is positioned close to the magnetic induction device in the form of a process chamber 10 having a plurality of spaced apart magnets 16, 18 positioned adjacent to and movably displaceable along the length of both upper and lower side regions of the process chamber 10 to create localized magnetic induction field regions. Conveyors 22, 24 carrying dry particles move through each of the outer surfaces of magnets 16, 18 on both sides of the chamber 10, but at mutually different relative speeds, creating regions of air-particle fluidization and agitation within the processing chamber 10, and then physical separation of the particulate feed material may occur based on their sensitivity to magnetic induction.

Description

Technical Field

[0001] The present disclosure relates generally to the field of processing magnetic materials, and more particularly to methods and apparatus for magnetizing dry, crushed ores to improve the efficiency of separation of certain minerals. The present disclosure relates to the design of magnetizing apparatus and methods for optimizing the performance of the apparatus in separating certain crushed, particulate ore materials, such as iron ore. Background Art

[0002] Magnetic separators used in mineral processing fall into three basic categories: low intensity, medium intensity and high intensity, with the rating being based on the relative magnetic field strength employed. The following magnetic separators are commonly used: WHIMS (wet high intensity magnetic separator) and LIMS (wet / dry low intensity magnetic set drum).

[0003] In each case, differences in the magnetic properties of various ore minerals (also known as their magnetic susceptibility) will determine their response to exposure to a magnetic field.

[0004] Magnetic separation can be used to separate valuable ferromagnetic minerals from non-magnetic gangue (e.g., separation of magnetite (with high magnetic susceptibility) from quartz). Other ferromagnetic minerals include those containing iron, nickel, and cobalt. The process can also be used to remove magnetic contaminants from other valuable minerals.

[0005] The magnetic susceptibility of other materials can be divided into two groups. Paramagnetic materials are attracted to magnetic fields, and those that are repelled by magnetic fields are called diamagnetic materials. Paramagnetic minerals of commercial interest include ilmenite, siderite, chromite, hematite, wolframite, and rutile.

[0006] Known magnetic separators can operate in either a dry or wet mode. Currently available magnetic classification equipment generally requires prior crushing of the run-of-mine mineral ore body to a maximum particle size of minus 100 μm, which may involve the production of a wet slurry and may require the introduction of air if dry particulate ore is passed to the magnetic classification equipment.

[0007] While crushed feed ore material is essential to the use of magnetic separators, most crushers have little or no control over which particles are crushed. The tendency is to over-grind and then use post-equipment classification devices (such as screens or cyclones or air classifiers) to direct some particles to continue on to further processing and those that need to be recovered to move back upstream for further destruction. Crushing in this manner inevitably results in the majority of the material being over-grinded to a particle size that is actually below the minimum product maximum size required to effectively release the valuable minerals, which is costly.

[0008] In particular, those size classifiers that suspend the particles in air or water are subject to "density selection" as well as particle size selection, resulting in further over-grinding of denser phases (such as high-density magnetite minerals) and under-grinding of less dense phases. As a result, considerable energy is wasted on over-grinding material, resulting in higher costs in terms of energy usage than is necessary to achieve the desired release size.

[0009] It would be useful to be able to provide an improved magnetic separation apparatus and method that can operate efficiently using a relatively coarse particle feed material stream and thus avoid the need to over-grind the source feed material upstream of the magnetic separator. This, in turn, can mean that a dry material handling process is possible. Avoiding over-grinding can reduce operating costs associated with crushing, grinding, and milling, and can also minimize the need for downstream systems to handle fine-sized feed material in the form of a wet slurry (requiring pumps and other slurry handling equipment, with increased operating costs) or alternatively use an air stream to convey dry, fine-sized feed material (which naturally generates dust, increases feed losses, and is expensive to operate).

[0010] It would be useful to be able to provide an improved magnetic separation apparatus and method which can operate efficiently to recover most of the valuable ferromagnetic and paramagnetic materials which may be present in a stream of particulate feed material and separate them as cleanly as possible from diamagnetic contaminants, while using a particle size which achieves mineral "release" without excessive grinding. Summary of the invention

[0011] In a first aspect, an embodiment of an apparatus arranged to induce magnetic properties in a flow stream of at least partially magnetizable dry particulate feed material to achieve subsequent particle classification thereof is disclosed, wherein in use the flow stream is fed into a dry separation station located adjacent to said magnetic induction apparatus, the apparatus comprising:

[0012] - a process chamber having an inlet and an outlet through which the flow stream enters and leaves the process chamber, respectively; and

[0013] a plurality of spaced apart magnetic sources positioned adjacent to and movably displaceable along the length of both the upper and lower regions of the processing chamber such that during said movement a respective magnetic source from each of the upper and lower regions forms a pair of magnetic sources aligned in opposing relationship to each other and spaced laterally apart relative to each other, each of said pairs of magnetic sources producing, in use, a local magnetic induction field region; and

[0014] - said upper region of the processing chamber and said lower region of the processing chamber, said upper region of the processing chamber being defined by at least one movable first surface element configured to move, in use, over the face of said spaced apart magnetic sources positioned above it, and said lower region of the processing chamber being defined by at least one movable second surface element configured to move, in use, over the face of said spaced apart magnetic sources positioned below it;

[0015] Wherein, during operation of the device:

[0016] - a second surface element conveys the flow stream of dry particles into the processing chamber via the inlet; and

[0017] - upon entering the processing chamber, the relative movement rate of the first surface element with respect to the magnetic source at an upper region of the chamber is greater than the relative movement rate of the second surface element with respect to the magnetic source at a lower region of the chamber, thereby creating a region of air-particle fluidization and agitation within the processing chamber due to the physical separation of the particulate feed material from the second surface element; and

[0018] - the combined effects of air-particle fluidization and agitation during exposure to said localized magnetic induction field region generated by said respective magnetic source pair results in physical sorting of said particles based on their susceptibility to magnetic induction such that:

[0019] - a portion of the feed material having a high sensitivity to magnetization is retained at the first surface element due to preferential attraction to a spaced-apart magnetic source positioned at an upper region of the process chamber;

[0020] - in the low magnetic field strength region in the process chamber positioned between the spaced-apart magnetic source pair, the portion of the feed material having medium sensitivity to magnetization is repelled by the spaced-apart magnetic source pair positioned both at the upper and lower regions of the process chamber and ultimately retained at the second surface element; and

[0021] -In an area adjacent to the spaced-apart magnetic source positioned at the lower area of ​​the processing chamber, a portion of the feed material having low sensitivity to magnetization is attracted to the spaced-apart magnetic source positioned at the lower area of ​​the processing chamber, and due to the repulsion of the spaced-apart magnetic source positioned at the upper area of ​​the processing chamber, the portion of the feed material having low sensitivity to magnetization is ultimately retained at the second surface element.

[0022] In some embodiments, a plurality of spaced apart magnetic sources positioned adjacent to the upper and lower regions of the process chamber are movably displaceable in the same direction in use. In one form thereof, the axial directions of movement of a row of upper and lower magnets are substantially the same, so that the magnets comprising the spaced apart magnet pairs move while at least partially facing each other in alignment to travel in the same linear direction from one end of the process chamber to the other.

[0023] In other forms, the spaced-apart pairs of magnets may be moved in at least partially aligned facing each other, but while the axial directions of movement of a row of upper and lower magnets are substantially linear, these axial directions may be oriented at angles to each other to produce other forms of localized magnetic induction field regions.

[0024] In some embodiments, each pair of magnetic sources is spaced apart in lateral space relative to each other by a predetermined distance. In one form thereof, equal lateral spatial distances between opposing end faces of the magnet pairs are applied across the entire length of the processing chamber as the two rows of magnets each move along parallel planar surfaces. The predetermined lateral distances between the magnet pairs are selected based on the particulate matter to be processed to provide a desired level of magnetic field strength between opposing magnets and to provide sufficient (but not complete) reduction in magnetic field strength in the space between adjacent magnet pairs as the adjacent magnet pairs move along the length of the processing chamber.

[0025] In some other forms, the faces of the two rows of magnets (and the relative positions of the first and second surface elements moving therethrough) may be arranged to be slightly offset from one another over the length of the processing chamber if desired, for example if a substantial build-up of deposited magnetised material may occur on the opposing surfaces of the upper and lower support elements facing the processing chamber in use. One way to achieve this is to arrange the magnet pairs so that their opposing end faces gradually separate from one another as they move through the length of the processing chamber, for example by arranging one or both of the opposing magnet pairs to be gradually recessed into their respective mountings.

[0026] In one example of such an arrangement, the magnets on the upper and lower sides of the process chamber are still at least partially aligned facing each other and travel in the same linear direction. However, while the axial direction of movement of a row of upper and lower magnets is substantially linear, the axial directions of the support members moving through the inclined upper surfaces of the magnets positioned on the respective upper and lower sides of the magnets may be in divergent, angled orientations relative to each other.

[0027] In some embodiments, a plurality of spaced apart magnetic sources positioned adjacent to both the upper region and the lower region of the processing chamber are respectively operably coplanar while being laterally spatially disposed relative to one another separated by a single predetermined distance therebetween.

[0028] In one exemplary form thereof, the lateral spatial distance between the opposing end faces of the magnet pairs as the two rows of magnets each move along parallel planar surfaces may be about 50 millimeters over the entire length of the processing chamber.

[0029] In another exemplary form thereof, the lateral spatial distance between the opposing end surfaces of the magnet pair may be about 20 millimeters over the entire length of the processing chamber.

[0030] In some embodiments, a plurality of spaced-apart magnetic sources are connected to corresponding movable support elements, which, in use, are operable by associated drive mechanisms to move the magnetic sources along the length of an upper region and / or a lower region of a processing chamber, wherein the movable support elements and associated drive mechanisms are connected to a frame that is disposed in a fixed relationship relative to the processing chamber.

[0031] In one form thereof, at least one of the movable support elements is operably movable in use by an adjustment mechanism to adjust the lateral spatial distance between magnetic sources aligned in a relative relationship with respect to each other at a processing chamber in use to reduce the strength of the local magnetic field region therebetween in use. For example, using the adjustment mechanism to change the lateral spatial distance between aligned pairs of magnetic sources can be achieved by lowering the relative position of the magnetic sources positioned at the lower region of the processing chamber by 30 mm, thereby expanding the predetermined lateral spatial distance between the magnet rows, for example, from 20 mm to 50 mm. Lowering the position of the magnetic sources positioned at the lower region of the processing chamber actually means adjusting the position of their movable support elements downwardly relative to the frame.

[0032] In other embodiments, changing the lateral spatial distance between the aligned magnetic source pairs can also be achieved by lowering the relative position of the magnetic source positioned at the lower region of the processing chamber, combined with raising the position of the magnetic source positioned at the upper region of the processing chamber, or as another alternative, only raising the position of the magnetic source positioned at the upper region of the processing chamber. Both options will result in the predetermined lateral spatial distance between the magnet rows being enlarged from, for example, an exemplary 20 mm gap therebetween to, for example, an exemplary 50 mm gap.

[0033] Of course, in cases where it is necessary to increase the strength of the local magnetic field region between magnetic sources aligned in relative relationship to each other in the processing chamber during use, the opposite action applies, wherein one or the other or both of the movable support elements can be operably moved by use of their respective adjustment mechanisms to reduce the lateral spatial distance therebetween.

[0034] An alternative way to achieve a reduction in the strength of the local magnetic field region between each pair of magnetic sources aligned in relative relation to each other at the processing chamber is to reposition the movable support element relative to the position of the second surface element. In some embodiments, the underside region of the processing chamber is defined by the movable second surface element, which is configured to move over and be supported by the faces of the spaced apart magnetic sources positioned directly below it when in use. In many embodiments, there is only a small lateral distance between the movable second surface element and the adjacent faces of the spaced apart magnetic sources.

[0035] However, in some other embodiments, the movable support element for moving the magnetic sources along the length of the lower region of the processing chamber is capable of being operably moved by an adjustment mechanism in use to adjust the lateral spatial distance of these magnetic sources relative to the second surface element, thereby reducing the intensity of the local magnetic field region experienced at the second surface element, provided that the second surface element remains in its original position. The inventors have observed that if the magnetic sources at the lower region of the processing chamber are moved downwardly so as to be offset below the second surface element, even by a small distance, the magnetic field intensity experienced by the particles at the second surface element is much less than the very strong field intensity remaining on the particles positioned at the upper surface element. In some exemplary embodiments, the inventors have determined that an offset as small as 5mm to 15mm is sufficient to cause the field intensity at the second surface element to be much less than the very strong field intensity at the first surface element.

[0036] In some embodiments, multiple pairs of magnetic sources aligned in relative relationship with each other at a processing chamber and delivering the highest intensity local magnetic field region therein are spaced apart from adjacent magnetic sources by a predetermined distance along the length of each corresponding movable support element, so that in use, a zone of relatively low magnetic field strength is operably achieved in the middle along the predetermined distance between each of the adjacent magnetic source pairs.

[0037] As above, in use, the high intensity induced magnetic field zone extends over the lateral spatial distance between each pair of magnetic sources. The predetermined distance between adjacent pairs of magnetic sources needs to be large enough so that there is a zone of low magnetic field strength in the middle between the zones of high magnetic field strength, and there is at least some induced magnetic field strength (rather than zero magnetic field strength). Particles of low magnetic susceptibility find themselves separated from the high magnetic field strength zone located between the opposing pairs of magnetic sources (usually by repulsion), and have a tendency to migrate to the low magnetic field strength zone located between these high intensity zones.

[0038] As before, there is also a way to further reduce the strength of the local magnetic field region experienced at the second surface element by relocating the support element (which holds the magnet near the underside area of ​​the support cavity) to a position offset from the second surface element.

[0039] The zone of low magnetic field strength advantageously provides sufficient induced magnetism to retain fine particles of low magnetic susceptibility at the second surface element, thereby also limiting the generation of dust particles in the air leaving the processing chamber. In practice, this means that if adjacent pairs of magnetic sources are spaced approximately 100 mm to 150 mm apart from each other, a zone of low magnetic field strength will be generated, depending on the magnetic field strength employed for the particulate material to be separated.

[0040] In some embodiments, each movable support element comprises an endless loop of support material, the endless loop being operably connected to at least two movable support rollers that rotate endlessly thereabout, and wherein each endless loop is operated by an associated drive mechanism in use. In one form, the two support elements are positioned directly above one another in use with a lateral spatial distance therebetween forming the height of the processing chamber. When viewed from above, the respective overlapping areas of the two support elements are associated with the uppermost planar dimension and the lowermost planar dimension of the processing chamber.

[0041] In some forms, the endless loop of support material may comprise a ribbed skeleton structure of wire or cable mesh, the skeleton structure being made of sufficiently flexible material to be both tensioned to form a rigid support for the magnetic sources, yet capable of deforming when moved in use through a 180 degree turn around each of the terminal rollers. In one form, each magnetic source is individually secured to a respective support element by first being positioned in a support bracket of similar shape and configuration, which bracket itself is securely attached to the support material using fasteners, or in another form, the support bracket is integrally formed with the support material.

[0042] In some embodiments, a plurality of spaced apart magnetic sources positioned adjacent to the upper and lower regions of the processing chamber are movably displaceable at the same relative rate of motion in use so as to form an arrangement of aligned pairs of magnetic sources that move together relative to the processing chamber. In order to produce the strongest local magnetic field region between the magnetic sources on each of the movable support elements, they need to move in opposite alignment with each other, which therefore means that they need to move at the same speed and, in some embodiments, be displaceable in the same generally linear direction in use.

[0043] In some embodiments, the first surface element and the second surface element or each of the first surface element and the second surface element is movably displaceable in the same direction (in use, the same linear direction) in use. In some embodiments, the maximum lateral spatial distance between the first surface element and the second surface element relative to each other is determined by the spatial position of the plurality of magnetic sources at the upper and lower regions of the processing chamber, because the respective first surface element and the second surface element are arranged to slideably move over the exposed face of each magnetic source.

[0044] In some embodiments, the first surface element and the second surface element or each of the first surface element and the second surface element comprises an endless ring, which is operably connected to a corresponding movable support device, and in use can be operated by an associated surface element drive mechanism to move the surface element along the length of the upper area and / or the lower area of ​​the processing chamber, wherein the movable support device and the associated drive mechanism are connected to a frame arranged in a fixed relationship with the processing chamber.

[0045] In some embodiments, each moveable support means comprises an endless loop of support material operably connected to at least two moveable support rollers which rotate endlessly thereabout, and wherein each endless loop is operated in use by an associated surface element drive mechanism.

[0046] In some embodiments, the or each first surface element and the second surface element are movably displaceable in use in the same direction.

[0047] In some embodiments, the or each first and second surface element is formed from a resilient, wear resistant structural material capable of supporting abrasive finely divided mineral material.

[0048] In some embodiments, the or each of the first surface elements is movably displaceable at a movement rate that is approximately 0.2 m / s-1.0 m / s faster than a movement rate of the spaced apart magnetic sources at an upper region of the process chamber.

[0049] In some embodiments, the or each of the second surface elements is movably displaceable at a movement rate of about 0.0 m / s-0.2 m / s faster than a movement rate of the spaced apart magnetic sources at the underside region of the processing chamber.

[0050] In some embodiments, the plurality of spaced-apart magnetic sources comprise permanent magnetic material.

[0051] In some embodiments, the plurality of spaced apart magnetic sources are formed from an electromagnetic material which is externally powered to induce magnetism in use.

[0052] In some embodiments, the portion of feed material having high susceptibility to magnetization comprises ferromagnetic granular material, the portion of feed material having medium susceptibility to magnetization comprises paramagnetic granular material, and the portion of feed material having low susceptibility to magnetization comprises diamagnetic granular material.

[0053] In some embodiments, the portion of feed material having a low susceptibility to magnetization may include a diamagnetic granular material that also contains unreleased ferromagnetic material and / or paramagnetic material.

[0054] In some embodiments, the portion of the feed material having a high sensitivity to magnetization is physically separated from the first surface element in a region outside of the processing chamber and in the absence of a spaced-apart magnetic source positioned adjacent thereto.

[0055] In some embodiments, the portion of the feed material having a medium susceptibility to magnetization is physically separated from the second surface element in a region outside of the processing chamber and in the absence of a spaced-apart magnetic source positioned adjacent thereto.

[0056] In some embodiments, the portion of feed material having low sensitivity to magnetization is physically separated from the second surface element in a region adjacent to but outside of the exit of the processing chamber, wherein the endless loop turns to travel in the opposite direction.

[0057] In further embodiments, instead of an open frame, the support for each of the functional units may be in other forms, such as a planar base plate having the necessary apertures through which the flow paths are directed in use, and the respective base plates having some other means (such as legs, flanges or other protrusions) for connecting directly to each other in a fixed spatial relationship, or alternatively fastened to an exoskeleton type structure.

[0058] In this specification, when the term "stack" is used, it refers to a plurality of the aforementioned magnetically classified stages that are placed adjacent to each other and functionally interconnected to form a rigid structure.

[0059] In use, dry particulate solids are slowly delivered onto the uppermost surface of the second surface element, for example via a suitable feeder inlet means such as a vibrating feeder.

[0060] In the disclosed method, feed particulate material (in the form of a particle stream having a relatively large top size compared to most magnetic separation devices) is passed as a thin layer between opposing pairs of magnets forming the magnetic induction processing chamber of the machine.

[0061] Throughout this specification, when the term "top size" is used it refers to the proportion of solid particles present in the feed material whose minimum width is greater than a predetermined size for the selected crushing particle size, usually noted as P80% through 100 μm, in other words, 80% of the particles are smaller than 100 μm and 20% are coarser.

[0062] In a second aspect, an embodiment of a method for inducing magnetism in a flow stream of at least partially magnetizable dry particulate feed material and achieving subsequent particle classification thereof using a dry separation device positioned proximate to a magnetic induction device is disclosed, wherein the device comprises:

[0063] - a process chamber having an inlet and an outlet through which, in use, the flow stream enters and leaves the process chamber respectively; and

[0064] a plurality of spaced apart magnetic sources located adjacent to and movably displaceable along the length of both the upper and lower regions of the processing chamber, arranged in use such that when laterally separated pairs of magnetic sources are positioned in alignment relative to one another, a local magnetic induction field region is generated therebetween, the laterally separated pairs of magnetic sources being from each of said upper and lower regions; and

[0065] a first surface element, the first surface element being moved in use over the face of a plurality of spaced apart magnetic sources located at the upper region, and a second surface element being moved over the face of a plurality of spaced apart magnetic sources located at the lower region

[0066] The method comprises the following steps:

[0067] - after transferring the particulate feed material onto the second surface element, causing the second surface element to convey the flow stream of particulate feed material via the inlet into the processing chamber; and

[0068] -set up

[0069] (a) First surface element

[0070] (b) a magnetic source at the upper region of the chamber,

[0071] (c) a second surface element, and

[0072] (d) Magnetic source at the lower area of ​​the chamber

[0073] the movement rate of (a) to (b) being greater than the relative velocity of (c) to (d), thereby creating a region of air-particle fluidization and agitation within the processing chamber due to the physical separation of the particulate feed material from the second surface element;

[0074] wherein the combined effects of air-particle fluidization and agitation during exposure to the localized magnetic induction field regions generated by the respective magnetic source pairs cause the particles to be physically sorted based on their susceptibility to magnetic induction such that:

[0075] - a portion of the feed material having a high sensitivity to magnetization is retained at the first surface element due to preferential attraction to a spaced-apart magnetic source positioned at an upper region of the process chamber;

[0076] - in the low magnetic field strength region in the process chamber positioned between the spaced apart magnetic source pairs, the portion of the feed material having a medium sensitivity to magnetization is repelled by the spaced apart magnetic source pairs positioned both at the upper and lower regions of the process chamber and ultimately retained at the second surface element; and

[0077] -In an area adjacent to the spaced-apart magnetic source positioned at the lower area of ​​the processing chamber, a portion of the feed material having low sensitivity to magnetization is attracted to the spaced-apart magnetic source positioned at the lower area of ​​the processing chamber, and due to the repulsion of the spaced-apart magnetic source positioned at the upper area of ​​the processing chamber, the portion of the feed material having low sensitivity to magnetization is ultimately retained at the second surface element.

[0078] In some embodiments of this aspect, features of the apparatus for inducing magnetism in a flow stream of the first aspect may be used to form steps for performing the method of this aspect.

[0079] Aspects, features and advantages of the present disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and illustrate, by way of example, the principles of any invention disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] The accompanying drawings help to understand the various embodiments to be described:

[0081] Figure 1 is a side schematic diagram of an apparatus for inducing magnetism in a flow stream of dry particulate material and achieving subsequent particle classification thereof according to the present invention, illustrating the principle of operation of a dry separation stage and a magnetic induction apparatus in a single-stage process.

[0082] Figure 2 Yes Figure 1 0 is a front perspective exploded view of some of the components used in the operation of the magnetic induction device shown in .

[0083] Figure 3 An end perspective side view of an apparatus for inducing magnetism in a flowing stream of dry particulate material and achieving subsequent particle classification thereof according to the present invention is shown, illustrating the combination of a dry separation stage and a magnetic induction apparatus in a single stage process.

[0084] Figure 4 It shows that Figure 3 A top side view of a portion of an embodiment of an apparatus for inducing magnetism in a flowing stream of dry particulate material and achieving subsequent particle classification thereof is shown in FIG.

[0085] Figure 5is a side schematic diagram of an apparatus for inducing magnetism in a flow stream of dry particulate material and achieving subsequent particle classification thereof according to the present invention, illustrating the principle of operation of a dry separation stage and a magnetic induction apparatus in a single-stage process.

[0086] Figure 6 A flow chart showing the process steps involved in the separation and recovery of magnetite mineral when using an apparatus for inducing magnetism in dry particulate material to improve particle classification according to the present invention.

[0087] Fig. 6A A flow chart showing the process steps involved in the separation and recovery of magnetite minerals using an apparatus for inducing magnetism in dry particulate material to improve particle classification according to the present invention and additional steps for the separation and recovery of hematite minerals.

[0088] Figure 7 A flow chart showing the process steps involved in the separation and recovery of paramagnetic minerals according to the present invention is shown, by using an apparatus for inducing magnetism in dry particulate material to improve particle classification to separate one or more of the following paramagnetic minerals: ilmenite, rutile, wolframite, chromite, siderite, hematite, and excluding diamagnetic minerals such as silica gangue. DETAILED DESCRIPTION

[0089] The present disclosure relates to features of a novel apparatus and method for magnetizing and then separating particulate solids, such as primary crushed ores from a mine, based on differences in their susceptibility to magnetization. In the past, such ores have been processed using only basic, known magnetic separation methods and process equipment.

[0090] The present disclosure also relates to a method of operating and controlling the apparatus for achieving the necessary separation of mineral species while minimizing the amount of energy consumed upstream involved in particle size reduction. Due to its configuration, the machine can operate using coarser sized feed particles, which in turn minimizes the tendency for over-grinding of the solid particle feed when compared to other ore separation apparatus known in the art.

[0091] With reference to the accompanying drawings, Figure 1 The apparatus shown in is an embodiment of a single stage dry particle separator, which may form part of a multi-stage dry particle separation and magnetization machine. In practice, a multi-stage machine may include a plurality of such separation stages arranged in series for repeated processing of ore particle feed material to provide more exposure time to the local magnetic field region for the particle feed material.

[0092] In some embodiments, different stations may be arranged in sequence to apply magnetic fields of different strength levels to the particulate feed material being processed, for example, the strength level may be arranged to increase from an initial low level from station to station, with the intent of more gradually separating the magnetized components. A series of stations may each be connected by appropriate chutes, pipes and conveyor systems, and all of the stations may be connected in a manner that facilitates the travel of the particulate feed material therethrough. The stations may be positioned on a common support structure, and may, for example, be positioned above each other to save floor space.

[0093] like Figure 1 As shown in FIG. 1 , the magnetic treatment chamber 10 is defined by a thin planar region in which a pair of magnetic sources 16, 18 are disposed at a predetermined distance 20 apart from each other in lateral space. Figure 1 and Figure 5 As shown in the figure, the same lateral spatial distance 20 between the opposing end faces of the magnet pairs 16, 18 applies to the entire length of the processing chamber 10, and the area is only used as a magnetic processing chamber when the rows of such magnets 16, 18 are each moved along the exemplary parallel planes on either side of the processing chamber 10.

[0094] The predetermined lateral distance 20 between these magnet pairs 16, 18 is selected based on the particulate matter to be processed to provide a desired level of magnetic field strength between the opposing magnets 16, 18. The selected magnetic field strength also needs to provide a region of low magnetic field strength in the lateral space between adjacent magnets on each side of the processing chamber 10, in the same plane of motion as the belts 22, 24.

[0095] exist Figure 1 In the embodiment shown in FIG. 1 , a plurality of spaced apart magnetic sources 16 positioned adjacent respective upper regions of the processing chamber 10 are each operably coplanar and laterally spaced apart from respective magnetic sources 18 by, for example, a single predetermined distance 20 therebetween.

[0096] In an exemplary form thereof, the lateral spatial distance 20 between the opposing end faces of the magnet pairs 16, 18 may be about 20 mm to 50 mm over the entire length of the processing chamber 10 as the two rows of magnets 16, 18 each move along their respective parallel planar surfaces. The entry point 12 and exit point 14 of the processing chamber 10 are positioned at positions where alignment between the opposing magnet pairs 16, 18 is terminated (when one of the magnets is rotated away from the corresponding other magnet in the pair).

[0097] The local induced magnetic field may affect the ore material or a mineral mixture containing at least some partially magnetizable dry particles therein and cause particle sorting thereof when a flowing stream of material is fed to a dry separation station located adjacent to said magnetic induction device.

[0098] The two sets of spaced-apart magnetic sources 16, 18 can be movably displaced in the same direction during use when connected to corresponding movable support elements by associated driving mechanisms, wherein the movable support elements (multiple movable support elements) and the associated driving mechanisms (multiple associated driving mechanisms) are connected to a frame that is arranged in a fixed relationship relative to the processing chamber 10.

[0099] A plurality of spaced apart magnetic sources 16, 18 located adjacent to the upper and lower regions of the process chamber 10 are movably displaceable in the same direction in use, for example as Figure 1 and Figure 5 As indicated by the arrow in .

[0100] In some forms, the endless loop of support material may comprise a ribbed skeleton structure of wire or cable mesh, the skeleton structure being made of sufficiently flexible material to be both tensioned to form a rigid support for the magnetic sources, yet capable of deforming when moved in use through a 180 degree turn around each of the terminal rollers. In one form, each magnetic source is individually secured to a respective support element by first being positioned in a support bracket of similar shape and configuration, which bracket itself is securely attached to the support material using fasteners, or in another form, the support bracket is integrally formed with the support material.

[0101] The first surface element and the second surface element are each in the form of a conveyor belt strip formed into an endless loop of rubber or other elastomeric material, elastic material, and are each operably connected by fasteners to a corresponding movable support device, which is shown in the form of a belt support frame. The belt support frame has an associated motor drive mechanism that is operable in use to move the belt support frame, which in turn moves the conveyor belt strip through the interior of the magnetic treatment chamber. Each of the conveyor belt strips and its corresponding belt support frame and associated drive mechanism are mounted to another structural frame that provides rigid support for these mechanisms so that when the conveyor belt strip moves during use, the shape and configuration of the magnetized treatment chamber is adjusted.

[0102] Each belt support frame comprises an endless loop of support material in the form of metal strips or metal mesh or metal wires operatively connected to at least two movable support rollers which rotate endlessly thereabout.

[0103] The first conveyor belt strip and the second conveyor belt strip are arranged to be movably displaceable in the same direction, as indicated by the arrows adjacent thereto. Figure 1 and Figure 5 These conveyor belts are formed of a resilient, wear-resistant structural material capable of supporting abrasive finely divided ore materials and are resiliently flexible.

[0104] In use, the first conveyor belt 22 is able to move at a faster speed than the speed of the magnets 16 on their respective endless loops of support wires 38 which move independently of the first conveyor belt 22 but are surrounded by it.

[0105] The second conveyor belt 24 is capable of moving at a faster speed than the speed of the magnets 18 on the endless loop of their respective support wires, which move independently of the second conveyor belt 24 but are surrounded by it.

[0106] For example, at the beginning of the process and between some stages, equipment for crushing (or for progressively regrinding) solid particulate material may be provided to achieve release of valuable minerals from surrounding gangue minerals found in the ore body. In use, once the previously oversized material has been dry ground (e.g., using a grinder) followed by a size separation process to provide dry crushed feed material of a pre-selected top size (e.g., using a vibrating screen or the like), the undersized particulate material can be fed into a sequence of solid magnetization processing stages to facilitate physical separation of the valuable particulate components.

[0107] If a regrinding step of the particulate material is performed between magnetizing stages downstream in the process, the undersized material is returned to a suitable point upstream of the series of magnetic separation stages for further attempts to magnetize the solids to facilitate physical separation of the valuable particulate components.

[0108] Based on experimental work using a magnetite ore body to separate magnetite, hematite and gangue minerals such as silica, the inventors believe that the design of the magnetic separation stage can operate satisfactorily with a feed particle size distribution of p80% passing 200 μm (micrometers), which is much coarser than typically used in prior art magnetic separators.

[0109] There are many ways of inducing rotational motion of the rollers. In one form, each roller is connected to a respective drive transmission mechanism to enable the roller to rotate about its own elongated axis, and each drive transmission mechanism is in turn connected to a motor drive in use to provide energy for rotation, as will be briefly described. The drive transmission mechanism and rollers are mounted on a support in the form of an open frame structure, or mounted at some other type of machine housing or structure.

[0110] Operation control system

[0111] A PLC control system is used to manage the roller rotation speed by taking feedback input from sensors that measure roller torque, roller load, roller surface condition of the two endless rings carrying each of the upper and lower movable magnetic sources and the two endless rings carrying the first and second surface elements.

[0112] For example, the PLC control system may also continuously monitor and subsequently adjust / adjust the predetermined lateral spatial distance between the magnet pair surfaces. Changing the proximity of the paired magnets may be accomplished by an actuation mechanism to cause a change in the lateral spatial distance between one or both of the endless rings carrying the upper and lower movable magnetic sources, and in some cases, a similar change in the lateral spatial distance may occur between one or both of the endless rings carrying the first and second surface elements.

[0113] The PLC control system can also continuously monitor and then adjust / regulate the rotational speed of the support rollers, as well as adjust the input rate of solid particles for magnetization and separation as needed (e.g., by controlling the rate and vibration of the vibratory feeder unit). The function of the PLC control system is to maintain a thin layer of feed solid particles on the support elements while maximizing the throughput of separated solid material in the machine and avoiding the need to use external air to remove particle accumulation or unclog blockages.

[0114] The PLC control system can also monitor and control the temperature of the roller bearings in the drive assembly housing and automatically re-lubricate the roller bearings in the drive assembly.

[0115] General Machinery Manufacturing

[0116] The modular construction of the machine allows any desired number of magnetic separation stages to be added in a single stack, or multiple stages can be stacked, and these stacks can be positioned side by side and connected via a bottom-to-top solids conveying system so the equipment does not become too tall. In any case, stacking (multiple stacks) represents a more efficient use of limited floor space than conventional separator technology.

[0117] The machine provides easy lateral access to the rolls themselves via the side walls to facilitate roll changes and belt changes, and to check the performance of the magnetic separation itself in producing the three magnetizable product material outputs.

[0118] The machine may have a dust proof enclosure for the roller pair stacking / crushing stage and also have one or more suction / extraction connections for dust removal of the interior of the induction and separation process chambers to remove and blockages caused by the accumulation of dust and fines. Connections may be located at strategic points around the apparatus to provide dust suppression and facilitate blockage removal, but in general the apparatus of the invention has been designed to avoid the necessity of any airflow driven product separation stage, or the necessity to remove it when a fine size final product is produced (nominally it will be coarse up to p80% through 200 μm (micrometers), but this depends on the application).

[0119] Solid particle feed input

[0120] Solid particles are fed into the machine via a vibrating batching chute or vibrating roller feeder or spreader onto a second surface element conveyor for transport into the magnetic treatment chamber.

[0121] Conveyor Belt

[0122] The conveyor belts used can have different material qualities (such as hardness and durability), adjusted to the needs of any product the machine is designed to carry, and can even include various roller surface corrugation forms and sizes. The belts used in the present invention can have various forms of central core belt reinforcement, such as wires or mesh arranged to extend the length of the belt and embedded through the middle of the belt thickness. Before maintenance replacement, the wear at the conveyor belt surface during use is evaluated by laser detector measurement.

[0123] Experimental Section

[0124] Essentially, the technology is adapted to the existing process of sorting ground ore according to its magnetic susceptibility. Thus, larger particles containing dilute quantities of strongly magnetic material and unreleased particles of other smaller magnetic materials are separated into a "middlings" stream. This stream is typically coarser in size than the feed material and is recycled for further comminution.

[0125] The product stream captures more liberated and strongly magnetic particles. This stream is also slightly coarser than the feed stream, which is one of the advantages of this technology - there is no need to grind the larger magnetite particles to P80 for all magnetite particles.

[0126] The tailings (gangue) stream is clean gangue which contains low concentrations of dilute small magnetite and hematite particles among the released gangue mineral particles. It is therefore expected to have a lower P80 than the feed stream, but most of it can be rejected in the primary grinding stage and is therefore several times the size of the magnetite released P80.

[0127] Finally, a cleaner process step is included, allowing the separation of a hematite-rich stream for further ultrafine grinding and beneficiation to obtain a hematite concentrate.

[0128] Figure 6 , Fig. 6A and Figure 7 The flowchart in the references the following information:

[0129] 1. Figure 6 The use of a dry magnetic separator in separating magnetite is shown in FIG. Fig. 6A As shown in , the dashed line represents an added hematite recovery process that also uses a dry magnetic separator with iron enhancement (most likely through recovered magnetite).

[0130] 2. Figure 7The figure shows the use of a dry magnetic separator in separating paramagnetic minerals from silica gangue. It can also be used to separate silica from unwanted paramagnetic minerals. The target paramagnetic minerals include ilmenite, rutile, wolframite, chromite, siderite, hematite and various rare earth host minerals.

[0131] Experimental Verification - Equipment

[0132] Laboratory-scale magnetic separators have been built, such as Figure 3 and Figure 4 shown.

[0133] The machine is of scale model size. An exemplary solid particulate ore material which has been previously pre-crushed is fed into the machine to simulate the finely divided ore being processed.

[0134] In each experiment, common equipment variable parameters such as feed rate of particulate feed material, belt speed and ambient temperature were measured. Based on past experience, the predetermined lateral distance between each pair of magnets on either side of the treatment zone between the upper and lower belts was selected. The results are summarized in the table below.

[0135] Experimental verification-result data

[0136] Table 1: Feed sample characteristics

[0137]

[0138] Table 2: Test parameters

[0139]

[0140] Table 3: Test results

[0141]

[0142] Experimental verification - conclusions drawn from the resulting data

[0143] Here are some key takeaways from the test results presented in this article:

[0144] 1. When processing a coarse sample such as Sample 1, the technology is able to recover a concentrate similar to that recovered in the DTR test and produce a middling stream of hematite and very low-release magnetite for regrind, while discharging a tailings stream with an iron content close to that of the gangue minerals (i.e., minimal loss of recoverable iron). It is predicted that in a full grind recovery test, once steady state is reached, the resulting concentrate grade will be >67%.

[0145] 2. This technology can achieve high recovery and near pure magnetite product when processing fully liberated ores such as sample 2. Less liberated and hematite can be recovered to middlings and further ground to liberated.

[0146] 3. When a single pass of a fine and nearly released ore stream is processed, the technology is able to recover a concentrate similar to that recovered in the DTR test, as well as a middling stream of unreleased magnetite and hematite for further grinding, while discharging a tailings stream with very low losses of recoverable iron.

[0147] 4. Testing has shown that hematite recovery has been achieved. However, in the samples tested, the particle size of hematite is generally smaller than that of magnetite, so further testing of the release and separation of hematite is required.

[0148] 5. Despite the prototype being narrow and not fully enclosed on the sides, the dust losses from the equipment are very low. As the ratio of working area to side length increases for commercial-scale equipment, dust losses are expected to decrease to negligible, especially given the addition of side curtains. This supports the argument that dust collection systems and baghouses are not required.

[0149] 6. Several tests were conducted at relative humidity above 60%. Dry systems will degrade in performance at high humidity. Testing showed no signs of performance degradation.

[0150] in conclusion

[0151] This article describes a magnetic separation technology that uses a number of innovative techniques. This technology solves the problem of over-grinding of solid particulate materials during comminution by showing that separation can be performed at a coarser average particle size, with the end result being a corresponding reduction in energy consumption. The magnetic separator disclosed in this article has many advantages over other particle separation technologies:

[0152] - Because the machine is designed to perform the above magnetic separation at a coarse particle size, it avoids the situation that usually occurs when a large portion of the feed material is over-grinded to below the minimum product size required (e.g., for mineral release from an ore). By keeping the particle size coarse, this also minimizes (or even eliminates) the need for air classifiers to remove ultrafine particles, compared to other processes that attempt to process ore bodies produced during over-grinding.

[0153] - In addition, since the machine is designed to provide magnetic separation of an average coarse particle size by avoiding over-grinding of the majority of the feed material, a substantial reduction in energy usage can be achieved. The inventors anticipate that the use of the novel machine can reduce by 40% the energy requirements of conventional production crushing and grinding equipment typically required to reduce particle size to the current p80% through 200μm size, which has been shown to achieve good separation, further refinement to the typical practice of grinding to p80% through 100μm crushed ore, and even as small as a p80% through 45μm (0.045mm) final product size.

[0154] In the foregoing description of certain embodiments, specific terms are used for clarity. However, the present disclosure is not intended to be limited to the specific terms so selected, and it should be understood that each specific term includes other technical equivalents that operate in a similar manner to achieve similar technical purposes. Terms such as "upper" and "lower", "above" and "below" are used as convenient terms to provide reference points and should not be interpreted as limiting terms.

[0155] In this specification, the word "comprising" should be understood in its "open" meaning, that is, the meaning of "including", and should not be limited to the "closed" meaning, that is, the meaning of "consisting only of..." When the corresponding words such as "comprise", "comprised" and "comprises" appear, they should be given the corresponding meanings.

[0156] The foregoing description is provided for several embodiments that may have common features and characteristics. It should be understood that one or more features of any one example may be combined with one or more features of another embodiment or other embodiments. In addition, any single feature or feature combination in any one embodiment may constitute an additional embodiment.

[0157] Additionally, the above describes only some embodiments of the present invention, and changes, modifications, additions and / or alterations may be made thereto without departing from the scope and spirit of the disclosed embodiments, which are intended to be illustrative rather than restrictive.

[0158] In addition, the present invention has been described in conjunction with what are currently considered to be the most practical and preferred embodiments, and it should be understood that the present invention is not limited to the disclosed embodiments, but rather, the present invention is intended to cover various modifications and equivalent arrangements within the spirit and scope of the present invention. In addition, the various embodiments described above can be implemented in conjunction with other embodiments, for example, aspects of one embodiment can be combined with aspects of another embodiment to achieve yet another embodiment. In addition, each independent feature or component of any given component can constitute an additional embodiment.

Claims

1. An apparatus arranged to induce magnetic properties in a flow stream of at least partially magnetizable dry particulate feed material to achieve subsequent particle classification thereof, said flow stream being fed, in use, into a dry separation station located adjacent to the magnetic induction apparatus, said apparatus comprising: - a process chamber having an inlet and an outlet, through which the flow stream enters and leaves the process chamber, respectively; as well as - a plurality of spaced apart magnetic sources positioned adjacent to both the upper and lower regions of the process chamber and movably displaceable along the length of both the upper and lower regions of the process chamber such that during said movement, respective magnetic sources from each of the upper and lower regions form a pair of magnetic sources aligned in opposing relationship to each other and spaced laterally apart relative to each other, each of the pairs of magnetic sources producing, in use, a localized magnetic induction field region; as well as - said upper region of said processing chamber being defined by at least one movable first surface element configured to move, in use, over the face of said spaced apart magnetic sources positioned above it, and said lower region of said processing chamber being defined by at least one movable second surface element configured to move, in use, over the face of said spaced apart magnetic sources positioned below it; Wherein, during operation of the device: - the second surface element conveys the flow stream of dry particles into the processing chamber via the inlet; and - upon entering the process chamber, the relative movement rate of the first surface element relative to the magnetic source at the upper region of the chamber is greater than the relative movement rate of the second surface element relative to the magnetic source at the lower region of the chamber, thereby creating a region of air-particle fluidization and agitation within the process chamber due to the physical separation of the particulate feed material from the second surface element; and - the combined effects of air-particle fluidization and agitation during exposure to said localized magnetic induction field region generated by said respective magnetic source pair results in physical sorting of said particles based on their susceptibility to magnetic induction such that: - a portion of feed material having a high sensitivity to magnetization is retained at the first surface element due to preferential attraction to the spaced-apart magnetic source positioned at the upper region of the process chamber; - a portion of the feed material having a medium sensitivity to magnetization in a region of low magnetic field strength in the process chamber positioned between the spaced-apart pair of magnetic sources is repelled by the spaced-apart pair of magnetic sources positioned both at the upper region and at the lower region of the process chamber and ultimately retained at the second surface element; and and -In the area adjacent to the spaced-apart magnetic source positioned at the lower area of ​​the processing chamber, a portion of the feed material with low sensitivity to magnetization is attracted to the spaced-apart magnetic source positioned at the lower area of ​​the processing chamber, and due to the repulsion of the spaced-apart magnetic source positioned at the upper area of ​​the processing chamber, the portion of the feed material with low sensitivity to magnetization is ultimately retained at the second surface element.

2. Apparatus according to claim 1, wherein the plurality of spaced apart magnetic sources positioned adjacent the upper and lower regions of the process chamber are movably displaceable in the same direction in use.

3. An apparatus according to claim 1 or claim 2, wherein each pair of magnetic sources are arranged to be separated by a predetermined distance relative to each other in lateral space.

4. Apparatus according to any one of the preceding claims, wherein the plurality of spaced apart magnetic sources positioned adjacent both the upper region and the lower region of the process chamber are respectively operably coplanar in use whilst being laterally spatially separated.

5. An apparatus according to any one of the preceding claims, wherein the plurality of spaced-apart magnetic sources are connected to corresponding movable support elements, which in use can be operated by associated drive mechanisms to move the magnetic sources along the length of the upper region and / or the lower region of the processing chamber, wherein the movable support elements and the associated drive mechanisms are connected to a frame, which is arranged in a fixed relationship relative to the processing chamber.

6. An apparatus according to claim 5, wherein at least one of the movable support elements can be operably moved by an adjustment mechanism during use to adjust the lateral spatial distance between the magnetic sources aligned in a relative relationship with each other in the processing chamber, thereby reducing the strength of the local magnetic field region there.

7. An apparatus according to claim 5, wherein the movable support element for moving the magnetic source along the length of the lower side area of ​​the processing chamber can be operably moved by an adjustment mechanism during use to adjust the lateral spatial distance of the magnetic source relative to the second surface element, thereby reducing the strength of the local magnetic field region experienced at the second surface element.

8. An apparatus according to any one of claims 5 to 7, wherein the plurality of pairs of magnetic sources aligned in relative relationship with each other at the processing chamber and delivering the local magnetic field region of highest intensity therein are spaced apart from adjacent magnetic sources by a predetermined distance along the length of each corresponding movable support element, so that in use, a zone of relatively low magnetic field strength can be operably achieved in the middle along the predetermined distance between each of the adjacent magnetic sources.

9. Apparatus according to any one of claims 5 to 7, wherein each movable support element comprises an endless loop of support material, said endless loop being operably connected to said at least two movable support rollers about which it rotates endlessly, and wherein each endless loop is operated in use by said associated drive mechanism.

10. Apparatus according to any preceding claim, wherein the plurality of spaced apart magnetic sources located adjacent the upper and lower regions of the process chamber are movably displaceable at the same relative rate of movement in use.

11. Apparatus according to any preceding claim, wherein the first surface element and the second surface element or each of the first surface element and the second surface element are movably displaceable in the same direction in use.

12. An apparatus according to any one of the preceding claims, wherein the maximum lateral spatial distance between the first surface element and the second surface element relative to each other is determined by the spatial positions of the multiple magnetic sources at the upper area and the lower area of ​​the processing chamber, because the corresponding first surface element and the second surface element are arranged to move slidingly over the exposed surface of each magnetic source.

13. An apparatus according to any one of the preceding claims, wherein the first surface element and the second surface element or each of the first surface element and the second surface element comprises an endless ring, which is operably connected to a corresponding movable support device, and in use can be operated by an associated surface element drive mechanism to move the surface element along the length of the upper area and / or the lower area of ​​the processing chamber, wherein the movable support device and the associated drive mechanism are connected to a frame arranged in a fixed relationship with the processing chamber.

14. Apparatus according to claim 13 wherein each movable support means comprises an endless loop of support material operably connected to said at least two movable support rollers about which they rotate endlessly, and wherein each endless loop is operated in use by said associated surface element drive mechanism.

15. Apparatus according to any preceding claim, wherein the or each first and second surface element are, in use, movably displaceable in the same direction.

16. Apparatus according to any preceding claim, wherein the or each first and second surface element is formed from a resilient, wear resistant structural material capable of supporting abrasive finely divided ore material.

17. An apparatus according to any one of the preceding claims, wherein the first surface element or each of the first surface elements is capable of being movably displaced at a movement rate that is approximately 0.2 m / s-1.0 m / s faster than the movement rate of the spaced-apart magnetic sources at the upper side area of ​​the processing chamber.

18. An apparatus according to any one of the preceding claims, wherein the second surface element or each of the second surface elements is capable of being movably displaced at a movement rate that is approximately 0.0 m / s-0.2 m / s faster than the movement rate of the spaced-apart magnetic sources at the lower side area of ​​the processing chamber.

19. Apparatus according to any preceding claim, wherein the plurality of spaced apart magnetic sources comprises permanent magnetic material.

20. Apparatus according to any one of claims 1 to 18, wherein the plurality of spaced apart magnetic sources are formed from an electromagnetic material which is externally powered to induce magnetism in use.

21. An apparatus according to any one of the preceding claims, wherein the portion of feed material having a high sensitivity to magnetization comprises a ferromagnetic granular material, the portion of feed material having a medium sensitivity to magnetization comprises a paramagnetic granular material, and the portion of feed material having a low sensitivity to magnetization comprises a diamagnetic granular material.

22. Apparatus according to claim 21, wherein the portion of feed material having a low susceptibility to magnetisation comprises a diamagnetic granular material which also contains unreleased ferromagnetic and / or paramagnetic material.

23. An apparatus according to any of the preceding claims, wherein the portion of feed material having a high sensitivity to magnetization is physically separated from the first surface element in a region outside the processing chamber and in the absence of a spaced-apart magnetic source positioned adjacent thereto.

24. An apparatus according to any of the preceding claims, wherein the portion of feed material having medium sensitivity to magnetization is physically separated from the second surface element in a region outside the processing chamber and in the absence of a spaced-apart magnetic source positioned adjacent thereto.

25. An apparatus according to any of the preceding claims, wherein the portion of feed material having low sensitivity to magnetization is physically separated from the second surface element in a region adjacent to the outlet of the processing chamber but outside the outlet of the processing chamber, wherein the endless loop turns to travel in the opposite direction.

26. A method for inducing magnetic properties in a flow stream of at least partially magnetizable dry particulate feed material and achieving subsequent particle classification thereof using a dry separation device located adjacent to a magnetic induction device, wherein the device comprises: - a process chamber having an inlet and an outlet, through which, in use, the flow stream enters and leaves the process chamber respectively; as well as - a plurality of spaced apart magnetic sources located adjacent to and movably displaceable along the length of both the upper and lower regions of the processing chamber, arranged in use such that when laterally separated pairs of magnetic sources are positioned in alignment relative to one another, said laterally separated pairs of magnetic sources being from each of said upper and lower regions, a local magnetic induction field region is generated therebetween; as well as - a first surface element, the first surface element being moved in use over the face of the plurality of spaced-apart magnetic sources positioned at the upper region, and a second surface element being moved over the face of the plurality of spaced-apart magnetic sources positioned at the lower region; The method comprises the following steps: - after delivering the particulate feed material onto the second surface element, causing the second surface element to convey the flow stream of particulate feed material via the inlet into the processing chamber; and -set up (a) The first surface element (b) the magnetic source at the upper region of the chamber, (c) the second surface element, and (d) the rate of movement of the magnetic source at the lower region of the chamber is such that the relative velocity of (a) to (b) is greater than the relative velocity of (c) to (d), thereby creating a region of air-particle fluidization and agitation within the processing chamber due to the physical separation of the particulate feed material from the second surface element; wherein the combined effects of air-particle fluidization and agitation during exposure to the localized magnetic induction field regions generated by the respective magnetic source pairs cause the particles to be physically sorted based on their susceptibility to magnetic induction such that: - a portion of feed material having a high sensitivity to magnetization is retained at the first surface element due to preferential attraction to the spaced-apart magnetic source positioned at the upper region of the process chamber; - in a low magnetic field strength region in the process chamber positioned between the spaced-apart pair of magnetic sources, a portion of the feed material having a medium sensitivity to magnetization is repelled by the spaced-apart pair of magnetic sources positioned both at the upper region and at the lower region of the process chamber and ultimately retained at the second surface element; and -In the area adjacent to the spaced-apart magnetic source positioned at the lower area of ​​the processing chamber, a portion of the feed material with low sensitivity to magnetization is attracted to the spaced-apart magnetic source positioned at the lower area of ​​the processing chamber, and due to the repulsion of the spaced-apart magnetic source positioned at the upper area of ​​the processing chamber, the portion of the feed material with low sensitivity to magnetization is ultimately retained at the second surface element.

27. A method according to claim 26, wherein further steps of the method utilize an apparatus as defined in any one of claims 2 to claim 24.

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