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WO2025171449A1 - Dispositif de broyage - Google Patents

Dispositif de broyage

Info

Publication number
WO2025171449A1
WO2025171449A1 PCT/AU2025/050127 AU2025050127W WO2025171449A1 WO 2025171449 A1 WO2025171449 A1 WO 2025171449A1 AU 2025050127 W AU2025050127 W AU 2025050127W WO 2025171449 A1 WO2025171449 A1 WO 2025171449A1
Authority
WO
WIPO (PCT)
Prior art keywords
fluid
particles
electromagnetic field
comminution device
disks
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/AU2025/050127
Other languages
English (en)
Inventor
Peter Lansell
David Lowe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SDH Australia Pty Ltd
Original Assignee
SDH Australia Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2024900378A external-priority patent/AU2024900378A0/en
Application filed by SDH Australia Pty Ltd filed Critical SDH Australia Pty Ltd
Publication of WO2025171449A1 publication Critical patent/WO2025171449A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C19/00—Other disintegrating devices or methods
    • B02C19/18—Use of auxiliary physical effects, e.g. ultrasonics, irradiation, for disintegrating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C7/00—Crushing or disintegrating by disc mills
    • B02C7/02—Crushing or disintegrating by disc mills with coaxial discs
    • B02C7/08—Crushing or disintegrating by disc mills with coaxial discs with vertical axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C7/00—Crushing or disintegrating by disc mills
    • B02C7/11—Details
    • B02C7/14—Adjusting, applying pressure to, or controlling distance between, discs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B03C1/02—Magnetic separation acting directly on the substance being separated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B03C1/02—Magnetic separation acting directly on the substance being separated
    • B03C1/30—Combinations with other devices, not otherwise provided for
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C19/00—Other disintegrating devices or methods
    • B02C19/18—Use of auxiliary physical effects, e.g. ultrasonics, irradiation, for disintegrating
    • B02C2019/183—Crushing by discharge of high electrical energy

Definitions

  • the invention relates to a comminution device for reducing size of particles of material in a fluid.
  • the invention also relates to a method for reducing size of particles of material in a fluid.
  • Grinding mills typically comprise a rotating drum through which hard rock is fed through.
  • the hard rock may be fed into the drum as dry material or in a slurry.
  • the drum may also comprise grinding media, such as balls or rods, which assist the mechanical crushing and grinding by compressing the rock.
  • Grinding mills include ball mills; autogenous (AG) mills; and semi-autogenous (SAG) mills. All of these grinding mills require a large amount of energy to operate they also require constant servicing to replace grinding media and wear components, such as mill liners.
  • the IsaMill is a low energy mill developed by Mount Isa Mines Limited and Netzsch Feinmahltechnik.
  • the IsaMill is a stirred mill that uses a number of large diameter disks inside a drum which rotate inside the mill stirring up the grinding media as well as the target ore.
  • the wear on the disks is rapid and as a result the disks need to be frequently replaced.
  • the present invention provides a comminution device for reducing size of particles of material in a fluid
  • the comminution device comprising: a chamber having an inlet for providing a feed of fluid containing particles of material of a size into the chamber and an outlet for allowing particles of material of a reduced size to exit the chamber; a pair of opposing surfaces within the chamber, the surfaces being separated from each other by a distance and being movable relative to each other in a direction transverse to at least one of the surfaces; and an electromagnetic field generator for generating an electromagnetic field between the surfaces, wherein said device is configured so that particles of material of a reduced size are obtained after subjecting the fluid to the relative movement of the surfaces and the electromagnetic field therebetween.
  • the present invention is directed to a device for reducing the size of solid particles in a fluid.
  • the device has applications in grinding fragments of rock to liberate or partially expose mineral ore therefrom.
  • the particles of material as described herein may include metalliferous or non-metalliferous or metalloid material.
  • Gold, iron-containing ores, and copper-containing ores are all examples of metalliferous materials.
  • Coal is an example of non-metalliferous material. Boron, silicon, germanium and arsenic are examples of metalloid materials.
  • the present invention uses electromechanical fracturing of particles to reduce their size.
  • the present invention may also liberate or partially expose mineral ore from the particles.
  • the partially exposed mineral ore may be more susceptible to downstream chemical processing than would otherwise be the case.
  • fluid refers to any material that acts as a fluid, for example exhibiting fluid dynamic properties such as viscosity, viscous shear forces, and a boundary layer.
  • fluid includes liquid mixtures such as slurries (i.e. water and solid particle mixtures) and fluidized streams (i.e. gas and solid particle mixtures).
  • Particle refers to a small portion of matter. Particles may be or include macroscopic, microscopic or nanoscopic fragments of rock and mineral ore.
  • the surfaces are separated from each other to define a comminution region therebetween. It will be appreciated that distance between the surfaces, and therefore the size of the comminution region, dictates the maximum size of the particles which may be received therebetween. It will also be appreciated that adjusting this distance will also adjust the maximum size of particle that the device can receive.
  • electromagnetic field refers to a classical (i.e. non-quantum) field produced by accelerating electric charges.
  • the electromagnetic field is generated as a result of a difference in electrical potential between the surfaces.
  • the electrical potential difference may exist independent of the flow of electrical current through the fluid or the induction of charge on the particles in the fluid.
  • a voltage can be applied across the surfaces in order to generate the electromagnetic field.
  • Subjecting the fluid to the electromagnetic field may result in particles being subjected to electrophoretic conditions.
  • Subjecting the fluid to an electromagnetic field can result in the particles within the fluid acquiring either a temporary or a permanent electrostatic charge, which can be used in downstream processing of particles outputted from the device.
  • Use of the device according to the invention may improve the efficiency of comminution when compared with typical grinding mills. It is believed that the combined effect of moving the surfaces relative to one another whilst generating an electromagnetic field may result in the overall improvement in efficiency.
  • this improvement in efficiency is, in part, due to tension being the dominant force responsible for the fracture of the particles.
  • the energy required to break a particle in tension may be significantly less than (e.g. only about 10% of) the energy required to effect breakage in compression.
  • a comminution device that works predominantly by applying tension loads to particles can provide significant energy savings.
  • Comminution processes may be performed on ore-containing materials in order to liberate valuable mineral from the material or reduce the particle size of the particles in order to facilitate downstream processing in order to recover the valuable mineral.
  • the relative movement of the surfaces may generate a standing wave instability.
  • These high pressure and/or temperature variations may result in tensile forces that act to pull the particles apart. This phenomenon can be, in part, described and solved for by applying nonlinear Schrodinger equations with supercritical nonlinearity.
  • High pressure and/or temperature variations within the fluid may be further amplified by the electromagnetic field between the surfaces.
  • the electromagnetic field may accelerate the flow of charged particles through the particles in the fluid.
  • the electrical resistivity may be significantly reduced across the line of maximum tension.
  • the electrical resistivity may depend on the composition of material(s) that form each particle.
  • the electrical resistivity may be reduced along a line passing through the part of the particle containing a valuable mineral or valuable species. For example, in a particle containing a valuable mineral (e.g. a metal such as gold), the path of least resistance for an electrical current through the material of the particle (e.g. valuable mineral bearing rock) will be through the centre of the valuable mineral.
  • a valuable mineral e.g. a metal such as gold
  • subjecting the particles to an electromagnetic field while also subjecting the particles to mechanical loads induced by the relative movement of the surfaces may generate a piezoelectric effect that can result in the maximum line of tension passing through a part of the particle containing the valuable mineral.
  • This phenomenon may be manifested as a reduction in resistivity across the line of maximum tension, the result of which is a tensile force that acts to fracture the rock to expose the valuable mineral contained therein.
  • This effect is referred to as “electromechanical fracturing” and “electromechanical fragmentation” throughout the specification.
  • comminution in accordance with the present invention may enhance exposure of valuable minerals from within a particle as a result of particle fracture and breakage.
  • breakage of a particle under tension through a region of valuable mineral may enhance liberation of valuable mineral into the fluid.
  • the flow of electrons within the fluid may alter the electrostatic charge distribution on the particles in the fluid which can aid in the separation of types of particles when processed.
  • subjecting particles of material to comminution in accordance with the present invention may result in the liberation of valuable mineral into the fluid.
  • the valuable mineral may be liberated as smaller particles composed of or comprising the valuable mineral.
  • valuable mineral also referred to herein as “valuable mineral-containing particles”
  • one or more valuable mineral-containing particles may contact one or more other valuable mineral-containing particles of the same or similar composition. After contacting, these valuable mineral-containing particles may agglomerate into a larger particle.
  • These larger particles may be substantially valuable mineral. That is, they may have a significantly higher proportion of valuable mineral than the average particle in the fluid. Accordingly, during the comminution process, particles with a concentrated content of valuable mineral may be formed.
  • Subjecting particles of material to comminution in accordance with the present invention may result in chemical dissociation of compounds in the particles.
  • subjecting particles of material to comminution in accordance with the present invention may result in the breakage of bonds within (valuable) minerals. The breakage of bonds may lead to the liberation of metal values from the mineral and/or formation of other chemical species within the fluid.
  • a similar phenomenon may be observed for particles that are “valuable material depleted”, i.e. smaller particles of valuable material in the bulk less valuable material, also agglomerate with each other due to this electrostatic effect.
  • valuable mineral-containing particles may agglomerate into flakes.
  • the average particle size of the comminution output (e.g. an output from the device of the first aspect) will have a smaller (finer) average particle size than an original input.
  • comminution may reduce the average particle cut size (d50%).
  • the output may have particle distributions such that the output may have a dlOO of ⁇ 10 microns and a d50 of ⁇ 5 microns.
  • the output particle size may range between 1 micron and 10 microns.
  • the surfaces may be substantially flat. However, one or each surface may have a change in profile. Examples of which include curved profiles and undulating profiles.
  • a change in profile in one or each surface may provide a variation in distance between the surfaces. It is believed that increasing the distance between the surfaces across the comminution region, towards the output of the region, may enhance the growth of the agglomerations and/or the degree of agglomeration of valuable mineral-containing particles.
  • the minimum output particle size is determined by the spacing of the disks
  • the minimum particle size is not solely determined by the spacing between the surfaces.
  • the boundary layer together with the electromagnetic field contribute to providing a minimum output particle size that can be significantly reduced when compared with a minimum output particle size of a conventional grinding mill.
  • the distance between the surfaces may be 3mm and the average size of the output particles may be less than 3 microns.
  • the boundary layer thickness may be altered by adjusting the distance between the surfaces and the relative speed of the surfaces.
  • the viscous shear forces in the boundary layer(s) may be altered by adjusting the distance between the surfaces and the relative speed of the surfaces.
  • a single boundary layer is formed between the respective surfaces. Viscous shear forces are more effectively transferred to the fluid via a single boundary layer as opposed to a pair of boundary layers (on respective surfaces) that are separated by a free stream flow. In the latter case, the free stream flow reduces the transfer of viscous shear forces between the boundary layers.
  • Boundary layer thickness will be determined by the physical characteristics and operating parameters of the device (such as the relative speed of the surfaces, the distance between the surfaces and roughness of the surfaces), the characteristics of the fluid (such as rheological properties of the fluid, the fluid velocity, density, viscosity, pressure and flowrate) and physical characteristics of the particulate material in the fluid (such as particle density and the particle effective diameter).
  • boundary layers formed on each surface will merge to produce a single boundary layer that has a thickness that is equal to or greater than the combined thickness of two boundary layers. Beyond a certain point, increasing the distance between the surfaces causes the single boundary layer to separate into two boundary layers. The maximum distance between the surfaces needed to produce a single boundary layer is determined by the fluid velocity and the viscosity of the fluid.
  • Fluid temperature is inversely proportionate to fluid viscosity. As such, a decrease in fluid temperature will results in an increase in fluid viscosity and therefore an increase in boundary layer thickness. Conversely, an increase in fluid temperature will result in a decrease in fluid viscosity and therefore a decrease in boundary layer thickness.
  • a Reynold’s number can be used to describe a flow regime that the fluid is operating under.
  • Reynold’s number is proportional to fluid density, fluid speed, length of the flow path and inversely proportional to dynamic viscosity of the fluid.
  • the flow regime is said to be laminar and for Reynold’s numbers greater than 2,000, the flow regime is said to be turbulent.
  • Laminar flow results in a thicker but smoother (i.e. less energetic) boundary layer. Turbulent flow results in a thinner but more energetic boundary layer.
  • Adverse pressure gradient effects the boundary layer thickness.
  • An adverse pressure gradient is a pressure gradient that increases in the direction of fluid flow. An increase in adverse pressure gradient results in a thicker boundary layer, and vice versa, up to a certain point, beyond this point boundary layer separation occurs.
  • An adverse pressure gradient can be produced by wall blowing, wall sucking or any other means known in the art.
  • the additive may comprise a rheology modifier.
  • the additive may alter the shear rate dependent viscosity of the fluid.
  • the additive may comprise a viscosity modifier.
  • the additive may alter the viscosity of the fluid.
  • the viscosity modifier may be of the type employed in wet grinding applications to enhance breakage kinetics.
  • the additive may comprise a density modifier.
  • the additive may alter the density of the fluid.
  • the additive may comprise a pH modifier.
  • the additive may alter the acidity or alkalinity of the fluid.
  • additives by CHEMFORCE ® are examples of commercially available additives that may be useful in one or more embodiments of the comminution device according to the present invention:
  • the Rehbinder effect is primarily attributed to the interaction of a liquid or surfactant with a solid surface, leading to a reduction in cohesion and an increase in plasticity or embrittlement.
  • the key mechanisms include:
  • This effect is particularly relevant in metals and alloys where the adsorption of hydrogen, sulfur, or other elements at the dislocation core can enhance plasticity or embrittlement.
  • SCC Stress Corrosion Cracking Relationship: The Rehbinder effect is closely related to stress corrosion cracking (SCC), where environmental agents weaken a material under applied stress.
  • the fluid may comprise one or more additives that give rise to a number of synergistic effects on the fluid.
  • an alkali hydroxide such as sodium hydroxide or calcium hydroxide may be added to the fluid as an additive. Hydroxide gels may be formed which can affect the rheology of the fluid. This change in rheology may increase the depth of the boundary layer which in turn increases the shear forces on the particles in the fluid.
  • alkali hydroxides e.g. sodium hydroxide and calcium hydroxide
  • alter the pH of the fluid the bulk conductivity of the fluid can be increased which may also increase the electrical conductivity of the fluid.
  • An increase in conductivity may also result in an increase in gas evolution which may fracture the particles as a result of cavitation.
  • the hydroxide-containing fluid may dissolve or extract material from the particles. In some embodiments, the hydroxide-containing fluid may be used to effect chemical comminution of the particles.
  • the output particles may be electrostatically charged.
  • the electrostatic charge on the particles may be directly proportional to its surface area when exposed to the electric field.
  • larger particles experience a higher voltage on their surface than smaller particles.
  • the electrostatic charge is temporary.
  • the electrostatic charge may decay over time at different rates depending on the composition of the individual particles. For example, the electrostatic charge may decay over period of less than an hour, such as over about 20 minutes, once the fluid is no longer subjected to the electromagnetic field of the comminution process.
  • the output may no longer separate into bands. That is, agitating particles that have separated into bands, after this time, may result in the bands being disrupted. Before any charge has dissipated below a threshold value, the particles may reorder into discrete bands after agitation.
  • the moveable surfaces may be rotatable relative to each other.
  • the moveable surfaces may be linearly slidable relative to each other.
  • one surface may reciprocate relative to the other.
  • the device may comprise a disk. At least one moveable surface may be located on the disk.
  • the moveable surfaces may be located on a pair of opposing disks. In some embodiments, the moveable surfaces may be located on a pair of opposing plates.
  • the disks may be coaxially arranged.
  • the device may comprise a shaft that rotatably supports at least one of the disks.
  • the disks may each have a shaft that are offset from each other.
  • the shaft may be upright. However, it is envisaged that the shaft may be arranged in any orientation. For example, it is envisaged that the shaft may be horizontally arranged when height restrictions are a consideration.
  • the device may comprise an adjustment mechanism that is configured to adjust the distance between the surfaces.
  • the adjustment mechanism can be used to adjust the distance between the surfaces to optimise performance of the boundary layer.
  • the distance between the surfaces may be adjusted to control the boundary layer(s) on the surfaces and therefore the viscous shear forces applied in the boundary layer(s).
  • the distance between the surfaces may be adjusted to control growth of the agglomerations.
  • the surfaces should be distanced enough to avoid electrical arcing between the surfaces, as will be discussed later in the specification.
  • the adjustment mechanism may apply a preload to the disks.
  • the preload may be directed inwardly, i.e. towards the surfaces.
  • the preload may resist a hydrodynamic load, directed outwardly, i.e. away from the surfaces, that results from fluid pressure of the fluid between the disks.
  • the hydrodynamic load is a function of the fluid properties (density and viscosity) and the surface area of the disks. When the fluid is water and the disks that are two metres in diameter, a hydrodynamic load greater than 300 tons forces the disks apart.
  • the device may comprise a housing that defines the chamber.
  • the housing may comprise a base and a side wall extending therefrom to form the chamber.
  • both disks When assembled, both disks may be positioned within the chamber of the housing.
  • the disks may be positioned at a spacing above the base of the housing. It can be appreciated that the spacing should be sufficient to allow movement of the disks.
  • the disks can be separated from each other to define a distance between the respective surfaces of the disks.
  • the distance between the surfaces dictates the maximum size of the particles that can be received by the device.
  • the disks may be positioned such that there is a gap between an edge of the disks and the side wall of the housing.
  • the size of the gap dictates the size of particles that can be outputted by the device.
  • the distance between the surfaces may be adjustable within the range of between 0.1mm and 100mm.
  • the distance may be between 0.1mm and 10mm, optionally between 0.5mm and 3mm, optionally about 1mm or about 3mm.
  • the comminution device may be used to process a slurry made from a stockpile of coarsely ground mineral ore. In these examples, it may be desirable to set the distance between 10mm and 100mm.
  • the comminution device may be used to process a slurry made from a stockpile of mineral tailings or finely ground mineral ore. In these examples, it may be desirable to set the distance less than 10mm.
  • one or each surface may have a profile that changes between the input and output from the comminution region.
  • the change in profile may be such that the distance between the surfaces increases or varies towards the output.
  • the profile may change so that the distance between the surfaces is: in the region at or near the input of between 10mm and 30mm, preferably 20mm; and in the region at or near the output of between 1mm and 5mm, preferably 1mm.
  • the movable frame may be positioned above the static frame. In some embodiments, the moveable frame may be positioned beneath the static frame.
  • the moveable frame and static frame are positioned in a side-by- side arrangement relative to a ground surface of an installation site.
  • One of the disks may be attached to the static frame.
  • the composite material may comprise a ceramic material. Ceramic compositions, which are not normally electrically conductive can be rendered conductive with the addition of carbon nanotubes. Carbon nanotubes may also increase the tensile strength of the ceramic. Ceramics typically have a low tensile strength.
  • the composite may comprise reaction bonded aluminium nitride.
  • the composite may comprise fused aluminium oxide grains.
  • the relative movement of the surfaces may be at a speed that is between 0.1 meters per second and 250 meters per second, optionally between 20 meters per second and 100 meters per second, optionally about 50 meters per second.
  • burst strength can be estimated based on the square root of the ultimate tensile strength of the material divided by the product of the material density and the radius of the disk.
  • a two meter diameter steel disk has a “burst speed” (i.e. a speed that the disk reaches its burst strength) of 3764 rpm, which translates to a surface speed of 599 meters per second. At this speed, the disk has 136 Megajoules of energy. Beyond the maximum surface speed, the disk is likely to fail.
  • the electrical potential difference between the surfaces may be between 1 volt and 30,000 volts, optionally between 10,000 volts and 30,000 volts, optionally between 20,000 volts and 30,000 volts.
  • the electrical potential difference between the surfaces may be less than 100 volts.
  • the electrical potential difference is between 10 volts and 30 volts.
  • the electrical potential difference is 25 volts.
  • the electromagnetic field generator may induce an electrical current through the fluid.
  • the electrical current may be at an amperage of between 1 milliamp and 70,000 amps, optionally between 100 amps and 1,000 amps, optionally between 500 amps and 1,000 amps.
  • the electrical current may be such that the electrical current density is between 1 milliamp/cm 2 and 50 amps/cm 2 .
  • the electrical current density is between 1 milliamp/cm 2 and 1 amp/cm 2 .
  • the electrical current density is 0.5 amps/cm 2 .
  • the current may be adjusted to provide the desired current density.
  • the electrical current density is inversely proportional to size (i.e. surface area) of the surfaces. That is, increasing the size of the surfaces will reduce the current density for the same electrical current.
  • the electrical current may be provided by a power source that provides direct current or an alternating current or a combination of direct and alternating current configured for current superposition.
  • the alternating current may be three-phase current.
  • the power source may a mains power source or an electricity generator. Examples of electricity generators include diesel generators, gas turbine generators, dynamos and alternators.
  • the electromagnetic field generator may produce an electrical frequency of between 1 hertz to 500 hertz, optionally between 10 hertz and 30 hertz, optionally between 20 hertz and 30 hertz.
  • the electrical frequency may be experimentally optimised to enhance comminution based on a particular ore that is being processed.
  • the electrical frequency may be single phase or three phase.
  • the inlet may be configured to direct fluid between the pair of opposing disks.
  • the outlet may be configured to offtake fluid from between the pair of opposing disks.
  • the outlet may be radially offset from the inlet.
  • the inlet may direct fluid in an axial direction relative to the disks.
  • the outlet may direct fluid in a radial direction relative to the disks.
  • the outlet may direct fluid in a tangential direction relative to the disks.
  • the inlet may be located at a centre of at least one of the disks.
  • the feed of fluid may be gravity fed into the inlet, for example, via a tank or vessel.
  • the feed of fluid may be pressure fed into the inlet, for example via a pump.
  • the outlet may be located at a periphery of at least one of the disks.
  • the above arrangement maximises the residence time of the fluid in the comminution region (i.e. space between the disks) by enabling the fluid to flow radially from the inlet to the outlet across the surfaces of the disks.
  • the inlet may be configured to direct the feed of fluid in a direction that is transverse to the direction of movement of the surfaces.
  • the inlet may have a tapered portion that tapers over a length, from a first diameter to a second diameter that is smaller than the first diameter.
  • the first diameter may be between 10mm to 200mm, optionally, between 20mm and 70mm, optionally around 50mm.
  • the second diameter may be between 0.1mm and 10mm, optionally between 0.5mm and 3mm, optionally about 1mm or about 3mm.
  • the length may be between 10mm to 200mm, optionally, between 20mm and 70mm, optionally around 50mm.
  • the electromagnetic field generator may be configured to produce a three-phase power supply.
  • a three-phase power supply is a power supply that can deliver a three-phase alternating current.
  • the electromagnetic field generator may be configured to produce a single-phase alternating current or direct current.
  • the electromagnetic field generator may comprise a power source, a transformer and a pair of opposing electrode assemblies.
  • the power source may be a generator or alternator.
  • the pair of opposing electrode assemblies may comprise a positive electrode assembly and a negative electrode assembly, wherein the positive electrode assembly comprises a positive electrode and the negative electrode assembly comprises a plurality of electrically isolated negative electrodes, each of the plurality of electrically isolated negative electrodes being configured to deliver a single phase of a three-phase alternating current to the positive electrode.
  • the strength of the electromagnetic field can be adjusted to result in more electromechanical fracture of particles.
  • the frequency of the current through the fluid between the disk may be adjusted so that the electrical current is close to or matches the resonant frequency of the particles.
  • the strength of the electromagnetic field may be adjusted to reduce the current between the negative and positive electrodes.
  • the electromagnetic field can be adjusted to reduce the electrical current to a level that is suitable to be turned off using relatively inexpensive switchgear.
  • Wear on the surface of the disks may be reduced by moving the disks about the second axis.
  • the invention also provides a slurry containing particles of material of a reduced size obtained using a process in accordance with the second aspect of the present invention.
  • a fourth aspect of the invention provides a process of recovering a valuable mineral from a slurry containing particles of material of a reduced size, wherein the slurry is in accordance with the third aspect and comprises a valuable mineral and the process comprises: subjecting the slurry to a recovery process to yield a valuable mineral.
  • the invention also provides a valuable mineral obtained according to the process of the fourth aspect.
  • Figure l is a perspective schematic view of a comminution device according to an embodiment of the present invention.
  • Figure 2 is a perspective schematic view of a comminution device according to another embodiment of the present invention that comprises a movable frame and a fixed frame;
  • Figure 3 A is a side schematic view of the comminution device shown in Figure 2 with the movable frame in a lowered position;
  • Figure 4 is a perspective schematic view of an electromagnetic field generator of the comminution device according to an embodiment of the present invention.
  • Figure 5 is a perspective view of an underside of an upper disk of the comminution device shown in Figure 4;
  • Figure 5A is a cross-sectional view of the upper disk through plane A in Figure 5;
  • Figure 6 is a schematic view of circuit comprising a variable frequency drive that is configured to allow adjustment of a strength of the electromagnetic field between the surfaces and to thereby amplify electrical current in the comminution device;
  • Figure 7 is a schematic view of an electrical safety system for use in the comminution device according to an embodiment of the present invention
  • Figure 8 is a schematic view of a hydraulic safety system for use in the comminution device according to an embodiment of the present invention.
  • Figure 1 shows a comminution device 10 according to an embodiment of the invention.
  • the device 10 comprises a housing 12.
  • the housing 12 may be a shell including a base 11 with a cylindrical side wall 13 extending therefrom to define a chamber 17.
  • the chamber 17 comprises two volumes: a main volume within which a pair of disks (an upper disk 14a and a lower disk 14b) are disposed; and a collecting volume that is located below the lower disk 14b.
  • the main volume is cylindrical whereas the collecting volume has a ring-shaped profile when viewed in plan with a semi-circular cross-sectional area.
  • the disks 14a, 14b have opposing working surfaces 15a, 15b, respectively.
  • both disks 14a, 14b When assembled, both disks 14a, 14b are positioned within the chamber of the housing 12.
  • the lower disk 14b is positioned above the base 11 of the housing 12.
  • a bottom surface of the lower disk 14b may be positioned at a spacing of 50mm and 200mm from an inner surface of the base of the housing.
  • the gap should be sufficient to allow the fluid to effectively exit from the device.
  • the upper disk 14a is positioned above the lower disk 14b, such that the surfaces 15a, 15b are separated from each other by a distance to define a comminution region therebetween.
  • this distance may be between 1mm and 20mm. In some embodiments, a distance of about 3mm may be used.
  • the disks 14a, 14b and housing 12 are configured such that there is a gap between an edge of the disks and the side wall of the housing 12. For example, this gap may be between 50mm and 200mm. The gap should be sufficient to allow the fluid to effectively exit from the comminution region.
  • the device 10 also comprises a frame 16 that supports the housing 12 and the upper disk 14a on the ground.
  • the frame 16 comprises a platform and a pair of upright supports.
  • the platform comprises a rectangular plate and four structural members that frame the parameter of the plate.
  • Each upright support comprises a pair of vertical structural members and a horizontal structural member.
  • the vertical structural members are attached (in this illustrated embodiment welded) to the members of the platform at a first end and are attached (in this illustrated embodiment welded) to the horizontal member at a second end.
  • the device 10 also comprises a motor 18 that is coupled to a lower disk 14b via an upright shaft 20.
  • the motor 18 is operable to rotate the lower disk 14b relative to the upper disk 14a in a direction transverse to the surfaces 15a, 15b.
  • the motor 18 is supported on the platform of the frame 16.
  • the motor 18 has the following specifications:
  • the electric motor speed is l,440rpm with a 3.5:1 reduction to give a rotational speed of 411 rpm at the shaft 20.
  • the reduction may be a mechanical speed reduction via a gearbox or for example, by increasing the number of poles on the electric motor.
  • the rotational speed may be selected based on the type of material that is being processed.
  • Increasing the rotational speed reduces the boundary layer thickness and increases throughput of the device. Conversely, reducing the rotational speed increases the boundary layer thickness and reduces the throughput of the device.
  • the shear effect may be increased with an increased rotational speed, depending on other factors that are described herein, such as the type of fluid and the boundary layer thickness.
  • the flow path of the fluid in the comminution region transitions from a linear or curved flow path to a spiral flow path.
  • the transition in flow path may increase residence time of the fluid within the comminution region.
  • the rotational speed of the surfaces will be selected bearing in mind the rheological characteristics of the fluid to be processed. If the speed is too low, inadequate comminution will occur.
  • the present invention may be uses to process fluids derived from mined material, such as tailings or a slurry made from “fresh” material.
  • the fluid may be an aqueous slurry comprising particulate mineral material, for instance clay, shale, sand, grit, metal oxides etc. admixed with water.
  • the fluid may be a non-cohesive slurry (e.g. a slurry rich in gravel or sand) or a cohesive slurry (e.g. slurry rich in loam, clay or silt).
  • the fixed part 16a comprises a pair of upright sections.
  • the upright sections support the housing 12 and the upper disk 14a.
  • Each upright section comprises a pair of vertical structural members and a horizontal structural member.
  • the vertical steel members are attached to the ground (in this illustrated embodiment bolted) at a first end and are attached (in this illustrated embodiment welded) to the horizontal member at a second end.
  • the movable part 16b comprises a platform and a plurality of adjustable leg members.
  • the platform supports the gearbox 28 and the lower disk 14b and can be raised and lowered via the adjustable leg members to adjust the distance between the surfaces 15a, 15b of the disks 14a, 14b.
  • Each adjustable leg member comprises a pneumatic bag 30 that can inflated/deflated to raise and lower the movable part 16b relative to the fixed part 16a.
  • Figure 3A shows the pneumatic bag 30 deflated and the movable part 16b in a lowered position.
  • the platform is formed from a rectangular plate with four structural members that frame the parameter of the plate.
  • FIG. 4 shows an electromagnetic field generator 22 according to one embodiment.
  • the electromagnetic field generator comprises a power source (not shown) such as a diesel generator/alternator, a transformer 32, a negative electrode assembly 34 and a positive electrode assembly 36.
  • the positive electrode assembly 36 is located on the lower (movable) disk 14b.
  • the transformer 32 is connected on an input side 29 to the power source.
  • the transformer 32 is connected on an output side 33 to the negative electrode assembly 34 via three phase connection (i.e. wires), as indicated by bus bars 31 and electrical terminals 37 on the stationary disk 14a.
  • the positive electrode assembly 36 is connected to neutral via a neutral connection (i.e. wire) 38.
  • the negative electrode assembly 34 comprises a composite layered structure 39, which will be discussed in more detail with reference to Figure 5.
  • the stationary disk 14a comprises an inlet opening 35 that feeds slurry from the inlet conduit 24 (as shown in Figures 1-3B) into the space between the disks 14a, 14b.
  • FIG. 4A shows the inlet opening 35 in more detail.
  • the inlet opening 35 is an orifice located at a centre of the stationary disk 14a.
  • the inlet opening 35 has a first section 35a that has a constant first diameter DI of around 50mm and a second, tapered, section, that tapers from the first diameter DI to a second diameter D2 of around 3mm over a length L of 50mm to 200mm.
  • the second, tapered, section is therefore an inverted cone shaped profile.
  • Particles entering the inlet opening 35 are ground down to 3 mm due to physical movement between the particles as well as an electrical force being exerted on them by the electromagnetic field generator 22. That is, in some embodiments, the fluid may be subjected to some degree of electromagnetic field before it enters the comminution region.
  • the positive electrode assembly 36 comprises a positive electrode 40 and a bush box 42.
  • a bush box 42 allows electrical connection between stationary and rotating parts.
  • the bush box 42 is configured to electrically connect the positive electrode 40 to the neutral connection 38 via the shaft 20 that drives rotation of the rotatable disk 14b.
  • the power source supplies three phase power to the transformer 32 which steps down the voltage and increases the electrical current on the output side of the transformer 32.
  • the transformer 32 has the following specification:
  • a radiator such as a triple radiator, may be used to minimise Ohmic losses from the transformer 32.
  • the transformer 32 allows the output voltage to be reduced to an amount that is low enough to avoid electrical arcing across the space between the disks. For example, as previously discussed, a voltage of less than 50 V is required to avoid arcing across a 3mm gap. By virtue of conservation of energy, an output electrical current from the transformer 32 is significantly increased. The increased output electrical current enhances the piezoelectric effect and therefore tensile fracturing of particles.
  • Figure 5 shows an underside of the stationary disk 14a and negative electrode assembly 36, which as previously mentioned has a composite layered structure 39.
  • the composite layered structure 39 comprises a top layer 46, a lower layer 47, and a middle layer 48.
  • the top layer 46 is made of conductive material (i.e. steel, copper, graphite, cermet and the like) and supports the electrical terminals 37 (not shown in Figure 5 - see Figure 4).
  • the lower layer 47 comprises three electrode segments 49a, 49b, 49c made of conductive material (i.e. steel, copper, graphite, cermet and the like).
  • the electrode segments 49a, 49b, 49c are separated from each other via a layer of insulating material M (i.e. ceramic material).
  • the insulating material electrically isolates the three segments from each other.
  • the middle layer 48 is made of insulating material (i.e. ceramic material).
  • the middle layer 48 electrically isolates the top layer 46 from the lower layer 47.
  • the middle layer 48 can be made from the same or different insulating material to the insulating material that separates the electrode segments 49a, 49b, 49c.
  • each electrical terminal 37 extend through the top layer 46 and the middle layer 48 to contact the lower layer 47.
  • each electrical terminal 37 provides an electrically isolated electrical connection to one of the electrode segments 49.
  • Each electrical terminal 37 is connected to one of the phases in the three-phase power from the transformer 32.
  • electrical current will flow across the space between the disks from each electrical terminal 37 to the electrode segments 49a, 49b, 49c in the respective phases to the positive electrode 40.
  • the relationship between the electrode segments 49a, 49b, 49c and the positive electrode 40 can be described as a “star” electrical connection.
  • the electrode segments 49a, 49b, 49c provide an even distribution of electrical current between the surfaces 15a, 15b of the disks 14a, 14b.
  • an electrical current of between 500 Amps and 1,000 Amps will be produced through the fluid between the disks.
  • the electrical current between the disks is sufficient to fracture particles in the fluid that are acted on by tensile forces resulting from the piezoelectric effect.
  • the magnetic field may be up to 20 Tesla.
  • the magnetic field may be between 0.5 and 1.5 Tesla.
  • the magnetic field may be between 5 Tesla and 20 Tesla. Isolated regions of the magnetic surface may produce a magnetic field of 20 Tesla which may correspond to a distributed magnetic field of 10 Tesla.
  • a Variable Frequency Drive can be used to control the electrical current going into/or out of the transformer 32 to be in-phase with the impressed current. This results in constructive interference which amplifies the electrical current through the fluid between the disks.
  • a VFD converts an input alternating electrical current (AC) to a rectified direct current (DC) via a rectifier and then modulates the rectified DC using pulse width modulation via an Insulated Gate Bipolar Transistor (IGBT) to an output AC of a different frequency.
  • IGBT Insulated Gate Bipolar Transistor
  • the VFD can be controlled to adjust the frequency of the output AC.
  • FIG. 6 shows a VFD 50 connected to transformer 32.
  • the VFD 50 monitors the electrical current through the fluid between the disks via a current meter 52 and modulates the frequency of current (in each phase) going into the transformer 32 to amplify the electrical current through the fluid between the disks.
  • the electrical safety system 60 comprises a plurality (three) first circuit 62 and a second circuit 72 in parallel.
  • Each first circuit 62 comprises a current transformer 64 that converts an electrical current across one of the bus bars 31 to a reduced (metered) current that is proportional to the electrical current across one of the bus bars 31.
  • the metered current is circuited, in series, through a variable resistor 66 and a fast response overload contactor, also referred to as a “shunt” 68.
  • the variable resistor 66 is set to a nominal load and amperage.
  • the variable resistor 66 allows the shunt 68, which is a commercially available product, to be repurposed for this application.
  • the shunt 68 is set to a predetermined current value that is proportionate to a maximum allowable electrical current across one of the bus bars 31.
  • the second circuit 72 comprises a control switch 74 connected in series with a field controller 76 of the generator 78.
  • the control switch 74 is configured to trip in response to the shunt 68 tripping.
  • the generator 78 has a separately excited field which is typically 40 to 300 volts and about 10 Amps.
  • the strength of the rotating magnetic field inside the generator 78 can be varied by adjusting the exited field using the field controller 76. This works on a similar principle to “Doubly Fed Field” control.
  • the shunt 68 will trip. Simultaneously, the control switch 74 on the second circuit 72 will also trip which interrupts power to the field controller 76, thereby reducing output current from the generator 78.
  • the electrical current produced by the generator 78 is reduced to around 100-150 Amps, as opposed to 57,000 Amps, which is a suitable current to be safely turned off using small inexpensive switchgear.
  • Two or more of the above-described electrical safety system 60 may be used in parallel for redundancy purposes.
  • the above-described electrical safety system 60 may be used in conjunction with fast acting fuses as an additional safety measure in the event that the electrical safety system 60 fails or is insufficient to shut down the electromagnetic field generator 22.
  • Figure 8 shows a hydraulic safety system 80 that comprises a separate fluid supply 82 (such as a tank or pressure vessel) that can be used to dump fluid into the feed, e.g. via the inlet conduit 24, of the comminution device 10/10’.
  • the fluid supply 82 prolongs a period in which a hydrodynamic load is acted on the disks and thereby provides more time to shut down the generator before the disks become sufficiently close enough to result in electrical arcing.
  • the boundary layers may be separated by a free stream flow of fluid.
  • viscous forces act on the fluid due to the no-slip condition at the surfaces 15a, 15b of the disks 14a, 14b.
  • viscous shear forces are acted on the fluid which imparts tensile forces on the particles of material in the fluid.
  • the tensile force generates mechanical stress in the particles of material.
  • Mechanical stress in the particles of material is increased using the electromagnetic field generator 22.
  • the electromagnetic field generator 22 passes an electrical current through the fluid which is converted to mechanical stress in the particles of material via the piezoelectric effect. The combined mechanical stress is sufficient to fracture the particles.
  • boundary layer(s) should be sufficiently developed, i.e. thick enough to exert enough viscous shear forces on the particles of material to result in sufficient size reduction of the particles of material.
  • the boundary layer(s) are sufficiently developed if an average size of the particles output from the comminution device is around 1,000 th of the size of the gap between the surfaces 15a, 15b of the disks 14a, 14b.
  • Additives may be used to increase the boundary layer adhesion or shear effect above distances greater than 6mm.
  • Tailings were taken from a mine in Newbridge, Victoria.
  • a slurry for the tailings was formed comprising a 3 : 1 ratio of water to solids.
  • the slurry was input into the comminution device, under the following conditions:
  • the slurry was drained into 20 litre buckets (a small amount of wash-out water was added) and the sample left to settle for 24-48hrs to form a sediment.
  • Control samples (prior to being processed by the comminution device) were also tested using the same standard fire assay test to assess the concentration of gold in parts per million (PPM) in the control samples.
  • Table 1 below provides results of material from a palecon at the Newbridge mine before and after being processed in the comminution device according to the above-described conditions.
  • Gold- containing tellurides include calaverite (AuTe2), petzite (AgsAuTe2), sylvanite ((Au,Ag)2Te4), krennerite (Aui- x Ag x Te2), muthmannite (AuAgTe2), montbrayite ((AuSb)2Te3), and kostovite (CuAuTe4).
  • Recovery of gold, using cyanide leaching, from telluride ores can be difficult. It may be that in unprocessed ore, as well as in cyanidation tailings, there is more gold than indicated by standard fire assays. Similar issues may arise in processing gold-bearing material containing iridium.
  • gold tellurides are present, without being bound by theory, it is believed that the comminution process may break the gold tellurium bond. This may lead to the in situ generation of tellurium dioxide and gold metal. Breakage of the gold tellurium bond may result in gold being present in a processed sample in a form that may be detected using fire assay techniques.
  • Statement 3 The comminution device of Statement 1 or Statement 2, wherein the distance between the surfaces is adjustable within the range of between 0.1mm and 100mm.
  • Statement 4 The comminution device of any one of the preceding Statements, wherein the moveable surfaces are rotatable relative to each other.
  • Statement 5 The comminution device of any one of the preceding Statements, wherein the moveable surfaces are located on a pair of opposing disks.
  • Statement 6 The comminution device of Statement 5, wherein the disks are coaxially arranged.
  • Statement 7 The comminution device of Statement 6, further comprising a shaft that rotatably supports at least one of the disks.
  • Statement 9 The comminution device of Statement 8, wherein the distance between the surfaces is adjustable within the range of between 0.1mm and 100mm.
  • Statement 11 The comminution device of Statement 10, wherein the movable frame is positioned above the static frame.
  • Statement 12 The comminution device of Statement 10 or 11, wherein the movable frame is movable in a direction defined by the longitudinal axis of the shaft.
  • Statement 13 The comminution device of any one of Statements 10-12, wherein one of the disks is attached to the static frame.
  • Statement 17 The comminution device of Statement 16, wherein the wear resistant material is a cermet.
  • Statement 24 The comminution device of Statement 22 or Statement 23, wherein the electrical current through the fluid is such that the electrical current density is between 1 milliamp/cm 2 and 50 amps/cm 2 , optionally, between 1 milliamp/cm 2 and 1 amp/cm 2 , optionally, 0.5 amps/cm 2 .
  • Statement 29 The comminution device of Statement 27, wherein the second diameter is between 0.1mm and 10mm, optionally between 0.5mm and 3mm, optionally about 1mm or about 3mm.
  • Statement 32 The comminution device of any one of the preceding Statements, wherein the electromagnetic field generator comprises a power source, such as a generator, a transformer and a pair of opposing electrode assemblies.
  • a power source such as a generator, a transformer and a pair of opposing electrode assemblies.

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  • Food Science & Technology (AREA)
  • Health & Medical Sciences (AREA)
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Abstract

La présente invention concerne un dispositif de broyage destiné à réduire la taille de particules d'un matériau dans un fluide, le dispositif de broyage comprenant : une chambre ayant une entrée pour fournir une alimentation en fluide contenant des particules de matériau d'une certaine taille dans la chambre et une sortie pour permettre aux particules de matériau de taille réduite de sortir de la chambre ; une paire de surfaces opposées à l'intérieur de la chambre, les surfaces étant séparées l'une de l'autre d'une certaine distance et étant mobiles l'une par rapport à l'autre dans une direction transversale à au moins l'une des surfaces ; et un générateur de champ électromagnétique destiné à générer un champ électromagnétique entre les surfaces, ledit dispositif étant conçu de sorte à obtenir des particules de matériau de taille réduite après avoir soumis le fluide au mouvement relatif des surfaces et du champ électromagnétique.
PCT/AU2025/050127 2024-02-16 2025-02-14 Dispositif de broyage Pending WO2025171449A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2024900378A AU2024900378A0 (en) 2024-02-16 Comminution Device
AU2024900378 2024-02-16

Publications (1)

Publication Number Publication Date
WO2025171449A1 true WO2025171449A1 (fr) 2025-08-21

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4973000A (en) * 1987-09-29 1990-11-27 Sunds Defibrator Industries Aktiebolag Method and apparatus for determining the contact position in a refiner
US6230995B1 (en) * 1999-10-21 2001-05-15 Micropulva Ltd Oy Micronizing device and method for micronizing solid particles
CN207839096U (zh) * 2017-09-18 2018-09-11 陈坚胜 一种改进的石磨装置
CN114227421A (zh) * 2022-01-12 2022-03-25 江苏益芯半导体有限公司 一种晶圆片表面加工用抛光机

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4973000A (en) * 1987-09-29 1990-11-27 Sunds Defibrator Industries Aktiebolag Method and apparatus for determining the contact position in a refiner
US6230995B1 (en) * 1999-10-21 2001-05-15 Micropulva Ltd Oy Micronizing device and method for micronizing solid particles
CN207839096U (zh) * 2017-09-18 2018-09-11 陈坚胜 一种改进的石磨装置
CN114227421A (zh) * 2022-01-12 2022-03-25 江苏益芯半导体有限公司 一种晶圆片表面加工用抛光机

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