EP0431965B1 - Magnettrennung von Material mit Wirbelströmen - Google Patents

Magnettrennung von Material mit Wirbelströmen Download PDF

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Publication number
EP0431965B1
EP0431965B1 EP90313317A EP90313317A EP0431965B1 EP 0431965 B1 EP0431965 B1 EP 0431965B1 EP 90313317 A EP90313317 A EP 90313317A EP 90313317 A EP90313317 A EP 90313317A EP 0431965 B1 EP0431965 B1 EP 0431965B1
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EP
European Patent Office
Prior art keywords
particles
magnetic field
eddy currents
microwave
radiation
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.)
Expired - Lifetime
Application number
EP90313317A
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English (en)
French (fr)
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EP0431965A3 (en
EP0431965A2 (de
Inventor
Edwin Harm Roos
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.)
De Beers Industrial Diamond Division Pty Ltd
Original Assignee
De Beers Industrial Diamond Division Pty Ltd
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Filing date
Publication date
Application filed by De Beers Industrial Diamond Division Pty Ltd filed Critical De Beers Industrial Diamond Division Pty Ltd
Publication of EP0431965A2 publication Critical patent/EP0431965A2/de
Publication of EP0431965A3 publication Critical patent/EP0431965A3/en
Application granted granted Critical
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    • 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
    • B03C1/23—Magnetic separation acting directly on the substance being separated with material carried by oscillating fields; with material carried by travelling fields, e.g. generated by stationary magnetic coils; Eddy-current separators, e.g. sliding ramp
    • 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
    • B03C1/005—Pretreatment specially adapted for magnetic separation

Definitions

  • THIS invention relates to a method and means for separating materials.
  • Mining operations almost invariably involve the extraction of valuable minerals which exist in very small quantities in the mined rock. This is particularly so in the case of valuable metals such as gold and silver.
  • US-A-4137156 discloses a method and apparatus in accordance with the precharacterising portion of claims 1 and 10 in which non-magnetic, conductive metals can be separated from mixtures by using a linear motor to provide a moving magnetic field.
  • DE-A1-2336035 discloses a method for separating mineral pyrites by irradiating a sample with electromagnetic radiation of frequency 2.45 GHz.
  • the invention provides a method of separating particulate material according to the electrical conductivity of the particles of the material, wherein the method comprises providing first means to generate a magnetic field and subjecting the particles to the field which by interaction with eddy currents in the particles causes movement dependent upon electrical conductivity, of electrically conductive particles; characterised by providing second means, separate to said first means, to generate microwave or radio frequency electromagnetic radiation selected to generate eddy currents in electrically conductive particles, and by irradiating the particles with the radiation substantially simultaneously with subjecting them to the magnetic field so that the eddy currents generated in the particles by the irradiation interact with the magnetic field to cause the movements.
  • the invention also correspondingly provides an apparatus for separating particulate material according to the electrical conductivities of the particles of the material, comprising first means for generating a magnetic field and means for locating the particles in a position in which they are subjected to the magnetic field whereby interaction of the field with eddy currents in the particles causes movements of electrically conductive particles dependent on their conductivities; characterised by second means, separate to said first means, for generating microwave or radio frequency electromagnetic radiation and arranged to irradiate the particles with the radiation simultaneously with subjecting the particles to the magnetic field so that eddy currents induced in the particles by the electromagnetic radiation interact with the magnetic field to cause said movements.
  • the particles are preferably irradiated with microwave radiation having a frequency in the range 109Hz to 3x1011Hz, or by radio wave radiation having a frequency in the range 104Hz to 109Hz.
  • the magnetic field may be a moving or stationary field.
  • the magnetic field may have a constant or varying intensity.
  • the particles are passed through a microwave chamber in which they are irradiated with microwave radiation and in which they are subjected to the magnetic field.
  • the particles are held in suspension in a liquid and are subjected to microwave irradiation and the magnetic field while so suspended.
  • the invention can be used to separate gold particles from other particles.
  • Fig. 1 shows an apparatus 10 which illustrates the principles of the method of the invention.
  • the figure illustrates a microwave chamber 12 in which is mounted a microwave generator 14 for generating microwaves having a frequency in the range 109Hz to 3x1011Hz.
  • a glass dish 16 is placed on a conductive shielding plate 18 in the chamber 12 and contains an aqueous colloidal suspension 19 of fine gold particles together with other non-magnetic, non-conductive particles.
  • a permanent magnet 20 is placed beneath the conductive plate 18 and means (not shown) are provided for moving the magnet in the direction of the arrow 22 in Figure 1.
  • the magnetic field lines associated with the magnet 20 are vertical in Figure 1.
  • the magnet With the microwave generator in operation, the magnet is caused to move in the direction of the arrow 22.
  • the microwaves induce eddy currents in the gold particles in suspension.
  • Such eddy currents interact with the moving magnetic field and give rise to an electromotive force which in this case urges the gold particles to move to the right in Figure 1, i.e. in the same direction as the magnet moves.
  • the microwave frequency will be chosen to induce eddy currents of the desired magnitude in the desired particles so that the movement of those particles can be predicted and the desired particles recovered apart from other particles. In other words, the desired particles will be specifically targeted.
  • a non-specific microwave frequency may be used to cause differing degrees of movement of the various particle types.
  • An apparatus such as that of Figure 1 can be of practical benefit in assay procedures where it is desired, for instance, to determine the gold content of an ore sample.
  • the gold fraction is recovered and a computation may be made of the gold content of the sample as a whole.
  • milled and crushed ore particles 32 are fed onto an endless conveyor belt 34.
  • the ore particles 32 contain a low concentration of small particles of valuable electrically conductive material, such as gold, which are to be separated from other non-conductive material or less conductive materials in the mass of ore particles.
  • the particles pass through a microwave chamber 40 in which they are subjected to microwave radiation having a frequency in the range 109Hz to 3x1011Hz. While being irradiated the particles pass between magnets 36 (only one visible in Figure 2) located above and below the belt 34.
  • the magnets may be shielded from the microwaves by plates similar to the plate 18 of Figure 1.
  • the field lines associated with the magnets are perpendicular to the belt, i.e. into the plane of the paper in Figure 2.
  • the magnets 36 are arranged at 45° to the direction of belt movement, indicated by the arrows 38.
  • the magnetic field itself is at 45° to the-direction of movement of the belt and particles.
  • the incident microwave radiation induces eddy currents in conductive particles. These eddy currents interact with the applied magnetic field to produce forces which tend to move the conductive particles sideways off the belt.
  • the exact frequency of the microwaves is chosen to produce eddy currents of sufficient magnitude in small conductive particles for the resultant electromotive force to be great enough to cause the relevant particles to fall sideways off the belt.
  • the remaining particles which are either non-conductive or less conductive than the particles which it is desired to separate are not moved off the belt and continue moving on the belt. Such particles are discharged over the discharge end of the belt for collection separately from those particles moved sideways off the belt.
  • the magnets 36 seen in Figure 2 may be arranged to move in a direction at right angles to the direction of movement of the belt up and down as viewed in Figure 2. Also, there can be a number of magnets 36 arranged side-by-side to produce a "sweeping" magnetic field acting on the particles. A sweeping electromotive force, resulting from the interaction of the eddy currents with the magnetic fields of the various magnets moves the relevant particles progressively in a sideways direction off the belt.
  • Radio frequency electromagnetic radiation in the frequency range 104Hz to 109Hz can also be used.

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  • Physical Or Chemical Processes And Apparatus (AREA)
  • Soft Magnetic Materials (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Load-Engaging Elements For Cranes (AREA)
  • Non-Insulated Conductors (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Glass Compositions (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)

Claims (10)

  1. Verfahren zur Trennung von Partikelmaterial nach der elektrischen Leitfähigkeit der Partikel des Materials, wobei das Verfahren folgende Schritte aufweist: Bereitstellen einer ersten Einrichtung (20) zur Erzeugung eines Magnetfelds und das Aussetzen der Partikel (32) dem Feld, wodurch durch Zusammenwirken mit Wirbelströmen in den Partikeln (32) von der elektrischen Leitfähigkeit abhängige Bewegungen der elektrisch leitfähigen Partikel verursacht werden; gekennzeichnet durch das Bereitstellen einer von der ersten Einrichtung (20) getrennten zweiten Einrichtung (14) zur Erzeugung von elektromagnetischer Mikrowellen- oder Radiofrequenzstrahlung, die zur Erzeugung von Wirbelströmen in elektrisch leitfähigen Partikeln geeignet ist, und durch Bestrahlen der Partikel (32) mit der Strahlung im wesentlichen in der Zeit, in der sie dem Magnetfeld ausgesetzt sind, so daß die durch die Bestrahlung in den Partikeln erzeugten Wirbelströme zur Bewirkung der Bewegungen mit dem Magnetfeld zusammenwirken.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Partikel (32) mit Mikrowellenstrahlung einer Frequenz im Bereich von 10⁹Hz bis 3x10¹¹Hz bestrahlt werden.
  3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Partikel (32) mit Radiofrequenzstrahlung einer Frequenz im Bereich von 10⁴Hz bis 10⁹Hz bestrahlt werden.
  4. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß das Magnetfeld ein sich bewegendes Magnetfeld ist.
  5. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß das Magnetfeld ein stationäres Magnetfeld ist.
  6. Verfahren nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daß die Partikel (32) eine Mikrowellenkammer (12,40) passieren, in der sie mit Mikrowellenstrahlung bestrahlt werden und in der sie dem Magnetfeld ausgesetzt werden.
  7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, daß die Partikel (32) auf einem Förderband (34) durch die Mikrowellenkammer (12) transportiert werden.
  8. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die Partikel in einer Flüssigkeit in Suspension gehalten und in diesem suspendierten Zustand der Mikrowellenbestrahlung und dem Magnetfeld ausgesetzt werden.
  9. Verfahren nach einem der vorhergehenden Ansprüche bei Verwendung zur Trennung von Goldpartikeln von anderen Partikeln.
  10. Vorrichtung zur Trennung von Partikelmaterial nach der elektrischen Leitfähigkeit der Partikel des Materials, mit einer ersten Einrichtung (20) zur Erzeugung eines Magnetfelds und einer Einrichtung (16,34) zur Anordnung der Partikel in einer Position, in der sie dem Magnetfeld ausgesetzt werden, wodurch ein Zusammenwirken des Felds mit Wirbelströmen in den Partikeln (32) Bewegungen der elektrisch leitfähigen Partikel in Abhängigkeit von deren Leitfähigkeit verursacht; gekennzeichnet durch eine von der ersten Einrichtung getrennte zweite Einrichtung (14) zur Erzeugung von elektromagnetischer Mikrowellen- oder Radiofrequenzstrahlung, die zum Bestrahlen der Partikel mit der Strahlung geeignet ist, und zwar in der Zeit, in der die Partikel (32) dem Magnetfeld ausgesetzt sind, so daß in den Partikeln (32) durch die elektromagnetische Strahlung induzierte Wirbelströme mit dem Magnetfeld zum Bewirken dieser Bewegungen zusammenwirken.
EP90313317A 1989-12-07 1990-12-07 Magnettrennung von Material mit Wirbelströmen Expired - Lifetime EP0431965B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA899361 1989-12-07
ZA899361 1989-12-07

Publications (3)

Publication Number Publication Date
EP0431965A2 EP0431965A2 (de) 1991-06-12
EP0431965A3 EP0431965A3 (en) 1991-08-21
EP0431965B1 true EP0431965B1 (de) 1994-06-15

Family

ID=25579930

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90313317A Expired - Lifetime EP0431965B1 (de) 1989-12-07 1990-12-07 Magnettrennung von Material mit Wirbelströmen

Country Status (7)

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EP (1) EP0431965B1 (de)
JP (1) JPH05345146A (de)
AT (1) ATE107194T1 (de)
AU (1) AU629073B2 (de)
BR (1) BR9006242A (de)
CA (1) CA2031663A1 (de)
DE (1) DE69009948T2 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NZ243065A (en) 1991-06-13 1995-07-26 Lundbeck & Co As H Piperidine derivatives and pharmaceutical compositions

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3463310A (en) * 1968-02-27 1969-08-26 Us Interior Separation method
DE2336035A1 (de) * 1973-07-14 1975-02-06 Rosenthal Technik Ag Vorbereitungsverfahren zur magnetischen aufbereitung von mineralgemischen
US4137156A (en) * 1975-03-21 1979-01-30 Occidental Petroleum Corporation Separation of non-magnetic conductive metals
JPS5274167A (en) * 1975-12-16 1977-06-21 Agency Of Ind Science & Technol Recovery of metals out of solid waste pieces
US4842721A (en) * 1982-10-19 1989-06-27 Raytheon Company Transversely inclined ramp separator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
& JP-A-52 74167 (KOGYO GIJUTSUIN) 21 June 1977, *

Also Published As

Publication number Publication date
DE69009948T2 (de) 1994-11-03
ATE107194T1 (de) 1994-07-15
JPH05345146A (ja) 1993-12-27
EP0431965A3 (en) 1991-08-21
AU629073B2 (en) 1992-09-24
BR9006242A (pt) 1991-09-24
DE69009948D1 (de) 1994-07-21
CA2031663A1 (en) 1991-06-08
AU6780790A (en) 1991-06-13
EP0431965A2 (de) 1991-06-12

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