Abstract: A process for regenerating used foundry sand having high oolitic level and, more particularly, a process as aforesaid wherein the used foundry sand is subjected to magnetic separation by one or more high power magnets for dividing the used foundry sand into a first highly magnetic stream containing a high degree of oolite particles and a second less magnetic stream having a relatively high degree of sand particles.

Abstract: Particles contained in a suspension are separated in accordance with their magnetic susceptibility and based on the variation in flow velocity of suspension. In order to achieve this magnetic separation, a pair of wall plates having at least one flat surface in which a plurality of ferromagnetic narrow wires are buried in parallel are positioned in parallel to each other with a small distance therebetween so that the flat surfaces are opposed to each other to form a channel. The suspension flows in a laminar state with different flow velocities through the channel in the longitudinal direction of the ferromagnetic wires. A magnetic field is externally applied to the channel in the direction perpendicular both to the flow direction and the wall plates. Particles are separated in accordance with their magnetic susceptibility and based on variation in flow velocity which interacts with the magnetic susceptibility.

Abstract: A magnetic separator for isolating magnetically-labeled substances of interest, such as immunological agents, from a non-magnetic test medium using a method of high gradient magnetic separation. The target substance is contacted with microscopic magnetic particles having a receptor for binding with the target substance. The test medium containing the magnetic particles is held in a non-magnetic container and placed into a gap within an arrangement of magnets for causing the magnetic particles to adhere to selected locations upon the interior wall of the container. The quantity of magnetic particles may be controlled to cause the magnetic particles collected upon the interior wall to form a monolayer. The magnets are arranged upon a yoke which may provide linear, surrounding multipolar, or partially surrounding multipolar configurations of magnetic pole faces about the gap.

Abstract: The present invention provides devices for performing binding assays. Such devices comprise (i) a reaction vessel where unbound and immobilized magnetically-labeled reagent are produced in relation to the amount of said analyte in said test sample; (ii) a separation means for partitioning said immobilized magnetically-labeled reagent and said bound magnetically-labeled reagent; (iii) a magnetic field generator means for the application of a magnetic field to said magnetically-labeled reagent; and (iv) a measurement means to assess the effect of said magnetic field on said magnetically-labeled reagent as a measure of the presence or amount of said analyte in said test sample. The device provided by the instant invention can run, for example, direct indirect, competitive, inhibition and sandwich assay formats.

Abstract: The present invention provides assay methods for performing binding assays, wherein the detectable label is a magnetically responsive material. Direct and indirect, competitive and sandwich assay formats are used to partition the magnetically attractable label between a solid phase and a fluid phase in proportion to the presence or amount of analyte in the test sample. The magnetic responsiveness of the magnetically attractable label in one or both phases results in the exertion of a force upon the label. By determining the extent of the force or influence of the force exerted upon the label, the amount of the analyte in the test sample is determined.

Abstract: A processing line forms a desired end product for a plastic extrusion machine by supplying raw plastic material to a shredder. The shredder forms partially-fused, irregularly-shaped chunks of the raw plastic. The use of the shredder eliminates the requirement of extraneous matter separation prior to feeding of the shredder. The output of the shredder is conveyed to a ram feeder after passing material separators, such as a magnet and/or a metal detector or the like. The ram feeder forces the chunks to an extruder which ultimately supplies liquified plastic to a pelletizer to form pellets. The pellets are transferred to a storage vat for reuse.

Abstract: Compounds and methods are disclosed for reversibly aggregating particles suspended in a liquid medium. The method comprises combining the liquid medium containing the particles with a polyionic polymer capable of aggregating the particles under conditions suitable for such aggregation. Thereafter, the particles are contacted with a chemical reagent capable of cleaving the polyionic polymer under conditions sufficient to reverse the aggregation. Optionally, magnetic particles are added to the liquid medium in the present method under conditions for non-specific binding and the medium including the aggregates is subjected to a magnetic field gradient to separate the aggregates from the medium. The compounds of the present invention are polyions. The aggregation of the particles is reversible upon contact with chemical agents which cleave at least some of the bonds within the polyionic polymer.

Abstract: Compounds and methods are disclosed for reversibly aggregating particles suspended in a liquid medium. The method comprises combining the liquid medium containing the particles with a polyionic polymer capable of aggregating the particles under conditions suitable for such aggregation. Thereafter, the particles are contacted with a chemical reagent capable of cleaving the polyionic polymer under conditions sufficient to reverse the aggregation. Optionally, magnetic particles are added to the liquid medium in the present method under conditions for non-specific binding and the medium including the aggregates is subjected to a magnetic field gradient to separate the aggregates from the medium. The compounds of the present invention are polyions. The aggregation of the particles is reversible upon contact with chemical agents which cleave at least some of the bonds within the polyionic polymer.

Abstract: In a process for separating relatively magnetic mineral particles P.sub.m having magnetic susceptibilities .chi..sub.m, with .chi..sub.m >0 from relatively non-magnetic particles P.sub.n, having magnetic susceptibilities .chi..sub.n, with .chi..sub.m >.chi..sub.n, all the particles are suspended in a liquid stream, which is supplied to a separating container. The container is provided with an inlet and an outlet and forms a passageway for the stream therebetween. Furthermore an arrangement of magnetizable matrix elements provided in the passageway is magnetized. The supplying and magnetizing are conditioned in such a way, that depositions of particles are obtained predominantly upon the downstream side of the elements. From all the particles magnetic particles P.sub.m are captured to an effective amount upon the downstream side, thereby resulting in a high grade deposition.

Abstract: Fine particle coal is beneficiated in specially designed dense medium cyclones to improve particle acceleration and enhance separation efficiency. Raw coal feed is first sized to remove fine coal particles. The coarse fraction is then separated into clean coal, middlings, and refuse. Middlings are comminuted for beneficiation with the fine fraction. The fine fraction is deslimed in a countercurrent cyclone circuit and then separated as multiple fractions of different size specifications in dense medium cyclones. The dense medium contains ultra-fine magnetite particles of a narrow size distribution which aid separation and improves magnetite recovery. Magnetite is recovered from each separated fraction independently, with non-magnetic effluent water from one fraction diluting feed to a smaller-size fraction, and improving both overall coal and magnetite recovery.

Abstract: The invention provides an apparatus and method for the preparation of a pharmaceutical composition comprising a complex of an antigen component and the corresponding antibody component in a pharmacologically acceptable carrier. The apparatus comprises a housing chamber for containing paramagnetic particles and a platform against which the housing chamber is releasably retained. The platform contains one or more magnets located adjacent to the housing chamber when the housing chamber is positioned on the platform. The platform is secured to a support which allows the platform, and thus the housing chamber, to be rotated between a vertical and a horizontal position.

Abstract: A method for beneficiating a kaolin clay which includes quantities of smectite contaminants to reduce the low and high shear viscosities of high solids aqueous slurries of the kaolin. The smectite is converted into a pillared clay by intercalating it with a polymeric cationic hydroxy metal complex wherein the metal is ferromagnetic or diamagnetic. The kaolin and pillared smectite is then subjected as an aqueous slurry to high intensity magnetic separation, to separate the pillared smectite, and the beneficiated kaolin is recovered as product.

Abstract: The present invention relates to a process for determining or detecting by immuno adherence a biological substance present in a sample, which consists in introducing the sample into a receptacle on whose walls there is a component which has a specific immunological affinity for the substance to be tested for, in adding magnetic particles on which there is a substance which has a specific immunological affinity for the substance to be tested for, in subjecting them to several successive magnetic actions in order to accelerate the deposition of the said particles onto the walls and to displace those which have not formed specific bonds with the substance to be tested for which adheres to the walls via the component with affinity which is fixed thereto, and in observing the particles deposited.

Abstract: Fine particle coal is beneficiated in specially designed dense medium cyclones to improve particle acceleration and enhance separation efficiency. Raw coal feed is first sized to remove fine coal particles. The coarse fraction is then separated into clean coal, middlings, and refuse. Middlings are comminuted for beneficiation with the fine fraction. The fine fraction is deslimed in a countercurrent cyclone circuit and then separated as multiple fractions of different size specifications in dense medium cyclones. The dense medium contains ultra-fine magnetite particles of a narrow size distribution which aid separation and improves magnetite recovery. Magnetite is recovered from each separated fraction independently, with non-magnetic effluent water from one fraction diluting feed to a smaller-size fraction, and improving both overall coal and magnetite recovery.

Abstract: Both a system and method are provided for remotely heating a polymeric material to a selected temperature. The system generally comprises particulate ferromagnetic material dispersed throughout the polymeric material to form a composite, wherein the particulate material has a Curie temperature that corresponds to the selected heating temperature, and a source of microwave energy for remotely applying a beam of microwave energy to the polymeric composite material. Preferably, the particulate ferromagnetic material comprises only about 2 percent of the total composite by weight. The polymeric material may be compliant, thermosettable plastic, and the Curie temperature of the particulate ferromagnetic material dispersed therein may advantageously be above the curing temperature of the polymer, such that the beam from the source of microwave energy may be used to remotely join surfaces or construct joints in composite structures.

Abstract: An Fc receptor protein conjugated with Ferritin binds to an exposed Fc region of an antibody to form a cell/Ferritin complex. Magnetic particles are added to the medium and bind to the complex. The magnetic particles when bound to the complex significantly enhance the magnetic field gradient of the complex such that it may be separated magnetically from the medium.

Abstract: The separation of silica or siliceous gangue from one or more desired minerals in an aqueous slurry via mechanical apparatus is improved by the addition of a small amount of an alkanol amine to the slurry. Examples of separation techniques benefiting from this technology include cyclones, tables and spiral separators.

Abstract: A process for improving the concentration of non-magnetic heavy minerals using a gravity-magnetic type separator, by the addition of a magnetic mineral or phase, such as magnetite, ilmenite, or iron filings, to the feed slurry. The addition of the magnetic material prior to feeding the gravity-magnetic separator results in an increase in the recovery of the non-magnetic heavy minerals in the feed, such as rutile, zircon, gold, tin, tungsten, etc.

Abstract: A process and apparatus for treating waste which contains ferromagnetic components, such as the grinding sludge from grinding ferromagnetic materials which contains ferromagnetic particles contaminated with water and oil, in which the waste is introduced into a separating tank containing a washing solution and mixed with the solution by stirring until the oil dissolves. Subsequently, a magnetic field is produced at the separating tank wall which causes magnetic components to accumulate on the wall. The wash solution is then filtered to remove non-ferromagnetic solids. The magnetic field is subsequently removed, and accumulated ferromagnetic components are released into the wash solution. The ferromagnetic components are then filtered out from the wash solution and dried, and the filtered wash solution is conveyed to an oil separation tank where oil separated from the waste is recovered.

Abstract: A method and apparatus for magnetically beneficiating a raw sample, such as coal or lunar soil is disclosed. The beneficiation is achieved using a novel of fractionating the sample into components of different magnetic susceptibilities. The results of the fractionation may be used to determine the type of magnet to be employed for large scale operations, as well as the appropriate fraction or fractions to be recovered for further processing.

Abstract: Disclosed is a method for forming a high magnetic parameter ferromagnetic material. The material has a distribution of magnetic parameters as solidified, and is separated into a first fraction having relatively high magnetic parameters and a second fraction having relatively low magnetic parameters. The method comprises applying a magnetic field to the materials, the magnetic field being high enough to magnetize the low magnetic parameter fraction, but low enough to avoid substantially magnetization of the high parameter fraction. Thereafter the fractions of material are magnetically separated.

Abstract: A magnetic field separation system includes a magnet unit having first and second pole members forming a linear gap with a relatively high magnetic field density therebetween. A flow chamber comprised of first and second optically transparent slides mounted so as to define a generally planar fluid pathway therebetween, passes a biological fluid over the linear gap at an angle, with flow through the pathway being accomplished by gravity and capillary action. Biological fluid, when sensitized to magnetic reaction, passes through the fluid pathway, thereby resulting in perceivable separation of the sensitized particles.

Abstract: A magnetohydrostatic centrifuge of unique geometry in which an elongated separation space is provided within the bore of an elongate cylindrically shaped multipolar magnet. Separations are accomplished both with and without rotation by passing particles to be separated through the separation space within a paramagnetic or ferromagnetic fluid. Certain separations are preferably made using a quadrupolar magnet configuration with a paramagnetic fluid, others with a quadrupolar magnet and a ferromagnetic fluid, and still others, with a sextupolar magnet and a ferromagnetic fluid. Efficient use is made of the magnetic field through the use of a plurality of inner ducts creating a plurality of thin, elongate separation channels characterized by long particle dwell time and short drift distances during the separation process. Significant throughput capacity is achieved in a system in which the magnetic medium is pumped through the separator.

Abstract: An apparatus for sorting recyclable materials including an inlet conveyor with a magnetic pulleys that directs magnetic objects out of the flow of recyclable materials. A vacuum inlet is positioned adjacent a stepped region of the conveyor so as to pull lighter weight materials out of the material flow. A size sorting conveyor separates larger objects from the smaller lighter weight objects, and heavier objects such as glass are conveyed to still another collecting region.

Abstract: Particles of a nonmagnetic material are rendered magnetic by contacting their surfaces with a magnetizing reagent comprising water containing particles of a magnetic material, each of which has a two layer surfactant coating including an inner layer and an outer layer. The inner layer covers the magnetic particle and is a monomolecular layer of a first water soluble, organic, heteropolar surfactant containing at least 3 carbon atoms and having a functional group on one end which bonds with the magnetic particle. The outer layer coats the inner layer and is a monomolecular layer of a second water soluble, organic heteropolar surfactant containing at least three carbon atoms and having a hydrophobic end bonded to the hydrophobic end of the first surfactant and a functional group on the other end capable of bonding with the particles to be magnetized.

Abstract: Separation of admixtures of particles, fluids or gases having different magnetic susceptiblities is effected by subjecting a moving stream of the mixture to simultaneous gravitational and magnetic forces in a manner such that relatively non-magnetic materials respond significantly to the gravitational force and relatively magnetic materials respond preferentially to the magnetic force.

Abstract: A process for separating special steel components from lump shredder scrap includes first removing the ferromagnetic content from the shredder scrap and thereafter dividing the shredder scrap into a normal size fraction and an undersize fraction. The undersize fraction is then treated by separating the special steel content from the undersize fraction by a magnetic drum having a field strength above 0.2 tesla.

Abstract: The specification describes specie-separating and concentration-enhancing methods and apparatus which operate on a substantially continual basis. The constituents of a mixture are separated according to their respective influencability by motion in the direction of a separation influence and the species of like net influencability are transported in substantially continuous streams, each of opposite net influencability running near each other, in a direction or directions transverse to the separation influence, the streams being in communication parallel to the separation influence so as to transfer at least one of the separable species from one stream to another stream by virtue of continued separation of influenceable species as the respective streams progress transversely to the separation influence. The two streams can run in the same direction (co-current) or in respectively opposite directions (countercurrent).

Abstract: An improved magnetic separator arrangement is provided. One major improvement relates to modifications facilitating utilization of relatively dense and tightly packed matrix material within races, through which a slurry of ore material passes during separation. The tightly packed matrix material is accommodated through utilization of flexible race walls, and compression and expansion mechanisms selectively operable to facilitate separation. A cover mechanism inhibits water flow turbulence, during an initial setting up of a magnetic field to entrap magnetic material within the matrix element of each race. A preferred retainer mechanism is provided which facilitates mounting of flap members for use in association with a cover mechanism, as well as retention of the matrix material in a desired position. In a preferred embodiment, the previous features are incorporated into a system fed with an ore material from an inner portion of a circular race, i.e. the center of a rotating drum.

Abstract: A process for treating effluents contaiing cyanide from mining operations wherein magnetic separation is used prior to treatment with hydrogen peroxide.

Abstract: Disclosed is a method for separating initially non-magnetized ferromagnetic material. The material has a distribution of magnetic parameters, and is separated into a first fraction having relatively high magnetic parameters and a second fraction having relatively low magnetic parameters. The method comprises applying a magnetic field to the materials, the magnetic field being high enough to magnetize the low magnetic parameter fraction, but low enough to avoid substantial magnetization of the high parameter fraction. Thereafter the fractions of material are magnetically separated.

Abstract: Separation of relatively magnetic and relatively non-magnetic particles suspended in a fluid medium is effected by feeding a stream of the medium across at least one end face of a magnet so as to cause the magnetic and non-magnetic particles to diverge and to be directed into separate collector channels.

Abstract: A magnetohydrostatic centrifuge of unique geometry in which an elongated separation space is provided within the bore of an elongate cylindrically shaped multipolar magnet. Separations are accomplished both with and without rotation by passing particles to be separated through the separation space within a paramagnetic or ferromagnetic fluid. Certain separations are preferably made using a quadrupolar magnet configuration with a paramagnetic fluid, others with a quadrupolar magnet and a ferromagnetic fluid, and still others, with a sextupolar magnet and a ferromagnetic fluid. Efficient use is made of the magnetic field through the use of a plurality of inner ducts creating a plurality of thin, elongate separation channels characterized by long particle dwell time and short drift distances during the separation process. Significant throughput capacity is achieved in a system in which the magnetic medium is pumped through the separator.

Abstract: A method for continuous separation of magnetizable paramagnetic and/or diamagnetic particles from a flowing fluid laden with the particles includes guiding the flow through a separation region, penetrated by a high-gradient magnetic field along a primary flow route. The particle-laden fluid flow of the separation region is supplied in the form of a multiplicity of partial flows, each passing through feed zones supplied from the direction of the outer periphery of the separation region and through feed openings of flow guiding bodies. The feed openings are distributed over the cross section of the separation region in the form of at least one feed hole field. The partial flows are then guided inside the separation region through at least one separation hole field of pole element orifices distributed over the cross section of the separation region and associated wall parts which are penetrated by the primary magnetic flux in the direction of the axes of their orificies.

Abstract: Method of automatically separating and cleaning silicon carbide furnace materials using magnetic separation techniques. In the method of the invention, crushed or particulate silicon carbide furnace materials are mixed with a magnetic powder. The lower grade silicon carbide particles are then separated from the first grade silicon carbide crystals using magnetic separation. Recoveries of at least 75% of the first grade silicon carbide are possible using the method of the invention. This method is also useful for the beneficiation of ores, minerals, or man-made materials.

Abstract: A process which is especially useful for effecting magnetic separation of magnetically attractable impurities from an aqueous clay slurry or suspension includes passing the suspension through a porous, ferromagnetic matrix while applying a magnetic field to the matrix, on which impurities are collected, and thereafter regenerating the matrix by flushing collected impurities therefrom with a flush liquid, e.g., water. The improvement comprises, after discontinuing the passage of the suspension through the matrix, but before passing flush liquid therethrough, admitting a pressurized gas, e.g., compressed air, into the separator to displace suspension retained therein, and recovering the displaced suspension. In addition, flush liquid retained in the matrix after the flushing step may be displaced therefrom by the compressed air. By displacing the retained suspension from the matrix with, e.g., compressed air, instead of a flush liquid, e.g.

Abstract: A process for the wet processing of kaolin clay which includes a step for physically removing discrete particles of colored impurities by high gradient magnetic separation (HGMS) in which all processing steps including HGMS are carried out with the feed clay slurry at high solids, above 50%, and the magnetically purified clay slurry is also recovered at high solids, above 50%. A feature of the invention is that the HGMS unit is operated in a novel manner such as to avoid the dilution of the magnetically purified clay slurry with water during all stages of HGMS treatment without adverse effect on the yield of magnetically purified clay.

Abstract: The invention is of a process for increasing the productivity and separation efficiency of a short-belt type dry magnetic separator such as is used for separation of magnetic iron ore from gangue. The process includes providing magnets extending in an arc within the pulley head which begins at a location spaced beyond the point where substantially all of the particles are thrown off of the belt surface in the direction of belt travel.

Abstract: A method for obtaining a purified fraction from a mixture using a magnetic fluid wherein the mixture is contacted with the magnetic fluid to preferentially sorb the fluid onto selected components so they become magnetized and the magnetic components in the so-contacted mixture are separated from the nonmagnetic components by passing the mixture through a magnetic field. The method finds particular use for obtaining a purified sample of crop seed from a mixture of crop seed and soil of the same size and texture and for separating nut shells from nutmeats.

Abstract: A method and mechanism for the magnetic separation of material from a fluid containing magnetic and non-magnetic material, passing the fluid through matrix containing canisters wherein the canisters are carried on a turret which moves axially and rotatably. In four quadrilaterally arranged locations, two canisters are supported in a separation position within coils until they are filled and then are moved axially and rotationally to cleansing stations while cleansed canisters are rotated and moved axially up into the separation stations. A distribution head connects to the turret for delivery of magnetic material containing fluid and cleansing fluid.

Abstract: A magnetic process and apparatus for separating out small electrically conductive particles dispersed in a finely ground, relatively non-conductive medium by means of magnetic fields. More specifically, a steady or relatively slowly varying field is provided, and a higher frequency magnetic field induces magnetic dipoles into the conducting particles, which are displaced by the steady magnetic field to thereby effect separation. The magnetic separation process selectively applies a force on a conductive particle so as to either remove it from the bulk of the non-conductive material or increase the concentration of conductive particles in a given volume of space. The effectiveness of the separation process improves with increasing size of the particle; however, the process can be used for particle sizes that would be classed as "very fine".

Abstract: A separator for the magnetic removal of magnetizable particles, consists of an application unit for the application and the transport of sample and buffer, a separating unit of plastic or glass for the removal of the magnetizable particles, and a collecting unit. The separating unit is provided with one or more electromagnets, which are able, owing to their magnetic force, to hold the magnetizable particles back in the separating unit.

Abstract: The invention relates to a matrix ring magnetic separator the induction bodies of which are formed by sieve nettings which are arranged vertically and stacked behind one another in the direction of the magnetic field in such a way that the intersections of the wires of one sieve netting are located on the free field of the adjacent sieve netting resulting in the formation of sieve netting assemblies which are springy in themselves in the direction of the magnetic field. Even at very high field strength gradients such a magnetic separator is distinguished by good possibilities for cleaning and can also be produced economically.

Abstract: Mineral particles are separated from solid carbonaceous fuel by using magnetic separation. A mixture of mineral particles, carbonaceous fuel, ferromagnetic particles and polyacrylamide in water is subjected to magnetic separation to remove a magnetized fraction enriched in mineral water.

Abstract: A process for concentrating gold and/or uranium minerals by rendering the nonmagnetic minerals magnetic or weakly magnetic by causing a coating to form on the surfaces of the minerals. The gold and/or uranium are concentrated by use of a gravity-magnetic separator or a suitable high intensity magnetic separator.

Abstract: A metal scavenging device is disclosed which includes a frame carrying a plurality of generally parallel spaced-apart scavenger elements. In one embodiment the elements are comprised of flat plates having parallel walls. In another embodiment the elements are comprised of plates having inclined walls with the walls adjacent plates forming V-shaped spaces. In another embodiment the elements are comprised of elongate cylinders. A control circuit is provided to apply electrical charges of opposite polarities to adjacent plates. The circuit is closed when metal bodies contact adjacent surfaces of the plates. Current flow through the bodies creates a magnetic field, and strong permanent magnets provide a flux attracting the field about the bodies which are wedged and captured between the plates. The circuit includes a normally closed circuit breaker switch together with an indicator bulb which provides a visual signal when a metal body makes contact between the plates.

Abstract: Method of automatically separating and cleaning silicon carbide furnace materials using magnetic separation techniques. In the method of the invention, crushed or particulate silicon carbide furnace materials are mixed with a magnetic powder. The lower grade silicon carbide particles are then separated from the first grade silicon carbide crystals using magnetic separation means. Recoveries of at least 75% of the first grade silicon carbide are possible using the method of the invention. This method is also useful for the beneficiation of ores, minerals, or man-made materials.

Abstract: The subject matter of the invention mainly relates to the technical areas of foundry, manufacture of parts by casting metal in moulds.The process consists in that after moulding the parts and stripping them from the moulds which were broken, during a first cycle the mixture resulting from the knock-out is recovered. This mixture being stored. This mixture is directed from the storage place to an intermediate container; then the mixture from the intermediate container is fed up to a sieve grading separator unit allowing to separate the grains or particles in several different grading batches; each one of these batches is directed to a separating table designed for separating chromite from silica; the chromite on the one hand and the silica on the other hand are recovered in containers.This invention mainly applies to the recovery of components of different densities, especially chromite and silica.

Abstract: A slag disposal method for disposing of slags produced in furnaces during iron or steel making processes comprises employing the steps of magnetic sorting of masses of crude slags of a size greater than a value ranging between 300 to 500 mm obtained from the furnaces into slags rich in iron (above about 50 to 60 percent) and slags not rich in iron (below about 50 to 60 percent) and then applying a compressive force to the slags rich in iron to cause a coarse crushing and/or deformation to reduce the size and at the same time increase the iron content due to the breaking and separation of the slags from the metal. Further magnetic sorting and sieving after griding are provided to obtain concentrates having high iron content and to improve recovery efficiency.