Abstract: The present invention relates to a process for separating at least one first material from a mixture comprising this at least one first material and at least one second material using magnetic particles with which the at least one first material agglomerates.

Abstract: The present disclosure generally describes techniques for separating semiconducting carbon nanotubes from metallic carbon nanotubes in a carbon nanotube dispersion. The semiconducting carbon nanotubes and metallic carbon nanotubes may be provided and dispersed in a fluid. Once the semiconducting carbon nanotubes attach to the amine-coated magnetic particles, a magnetic field may be applied to the amine coated magnetic particles and attached semiconducting carbon nanotubes to attract and hold at least a portion of the semiconducting carbon nanotubes, so that the semiconducting carbon nanotubes may be separated from the fluid and/or metallic carbon nanotubes.

Abstract: The present invention relates to a process for separating at least one first material from a mixture comprising this at least one first material and at least one second material, which comprises the following steps: (A) contacting of the mixture comprising at least one first material and at least one second material with at least one surface-active substance, if appropriate in the presence of at least one dispersant, resulting in the surface-active substance becoming attached to the at least one first material, (B) if appropriate, addition of at least one dispersant to the mixture obtained in step (A) to give a dispersion having a suitable concentration, (C) treatment of the dispersion from step (A) or (B) with at least one hydrophobic magnetic particle so that the at least one first material to which the at least one surface-active substance is bound and the at least one magnetic particle become attached to one another, (D) separation of the addition product from step (C) from the mixture by application of

Abstract: A device for treating an analyte using magnetic beads is provided wherein the surfaces of the magnetic beads are effectively available as a whole. The device comprises a housing having a channel therein, through which channel the analyte is moved; a pair of electromagnets which are oppositely arranged in such a manner that the channel is interposed therebetween; a moving means for moving the pair of electromagnets along the channel while the electromagnets are facing the channel; and a controlling means for controlling magnetic forces generated by the electromagnets. The device is characterized in that the magnetic forces of the electromagnets are alternately generated with time. This will cause the magnetic beads to collide successively with the inner surface of the channel, which in turn gives a more efficient dispersion of the magnetic beads even if they are clustered or agglutinated to each other.

Abstract: System and method for a continuous process for separating particles according to their magnetic properties such as Curie point includes a feed of hot particles having different magnetic properties on a moving surface spaced above a stationary magnetic assembly. The temperature of the bed of particles is controlled to enable selective separation of different factions of particles based upon the temperature of the particles. The magnets are maintained substantially below their Curie point. Gaseous nitrogen is fed into and from the inside of the magnetic assembly to enhance the cooling of the magnetic assembly and to inhibit oxidation. The gas exits through high temperature bearings to inhibit debris therein. A thermal shield is placed between the moving surface and the magnets and below tubes carrying a cooling fluid to maintain magnets substantially below their Curie point. The entire process is contained with an inert gas-purged cabinet.

Abstract: A process for the beneficiation of trona includes supplying a trona feedstream that is crushed and dried. The trona is then separated into a first size fraction and a second size fraction. Impurities are removed from the first size fraction using at least one magnetic separator. The magnetic separator includes a plurality of stages. Each stage includes a conveyor system comprising a first end, a second end, and a conveyor belt. Each stage also includes a magnetic roller disposed at the second end of the conveyor system and a splitter disposed adjacent the second end of the system for separating a fraction of magnetic impurities from the trona to create a beneficiated fraction. At least one conveyor belt is deionized. Airborne dust particles are removed from an area surrounding at least one conveyor system.

Abstract: In an electrostatic separator or a magnetic separator, prior to electrically charging or magnetization of particles in order to carry out separation of mixed powder of particles having different properties from each other, classification is performed by a classifier so that the content of fine powder having a spherical equivalent diameter of 10 ?m or smaller is 15 mass % or less. After the classification, prior to electrostatic separation or magnetic separation, an operation of dispersing the mixed powder of particles may be carried out.

Abstract: A pulse of over six kilovolts with a duration of 200 nanoseconds causes an explosion that fragments a mineral deposit with metals embedded therein. The fragmentation separates the metals from the mineral. A conditioning electromagnet temporarily magnetizes the metals. A sorting magnet attracts one of the magnetized metals.

Abstract: The present invention is concerned with the adsorption of chiral molecules at surfaces or interfaces, with the arrangement and properties of adsorbed chiral molecules, and with devices and methods based thereupon. In particular, an apparatus allows the influence of the magnetic environment of the adsorbed chiral molecules by means of a magnetic field. The new observed orientation of the adsorbed chiral molecules caused by the chiro-magnetic effect, and the possible applications, are disclosed too.

Abstract: The present invention is embodied in a system for collecting biological samples from air including a collection assembly to store at least one biological sample and a separator to remove selected particles from the air prior to entry into the collection assembly. In one embodiment, the selected particles are magnetic and the separator includes at least one magnet to attract the particles from the air.

Abstract: Methods, systems and media for separating polymer mixtures. A mixture including polymeric components is provided. A particulate media is added to the mixture, where the particulate media can selectively mediate a triboelectric charging of the polymer mixture. The media includes a polymeric material having a selected position within an electrostatic charging sequence and a functional additive. The mixture is triboelectrically charged with the media. Two or more components of the polymer mixture are separated according to the triboelectric charge. A portion of the particulate media can be recovered using a recovery process, where the functional additive is selected for compatibility with the recovery process.

Abstract: The magnetic susceptibility of one or more plastic articles is enhanced to enable their separation from a waste stream using magnetic separators. An amount of paramagnetic material is added to the plastic formulation to influence magnetic susceptibility without affecting the properties associated with the function of the plastic article. The material is preferably selected from a group consisting of magnetite, ferro-silicon and ferromagnetic particles (e.g., iron filings). The amount or material can be varied in the range of between 0.05% and 5% by weight of the plastic formulation. The plastic with altered magnetic susceptibility and a method separating that plastic from a waste stream are also disclosed.

Abstract: The magnetic susceptibility of one or more plastic articles is enhanced to enable their separation from a waste stream using magnetic separators. An amount of paramagnetic material is added to the plastic formulation to influence magnetic susceptibility without affecting the properties associated with the function of the plastic article. The material is preferably selected from a group consisting of magnetite, ferro-silicon and ferromagnetic particles (e.g., iron filings). The amount or material can be varied in the range of between 0.05% and 5% by weight of the plastic formulation. The plastic with altered magnetic susceptibility and a method separating that plastic from a waste stream are also disclosed.

Abstract: The method for manufacturing alloy powder for R—Fe—B type rare earth magnets of the present invention includes a first pulverization step of coarsely pulverizing a material alloy for rare earth magnets and a second pulverization step of finely pulverizing the material alloy. In the first pulverization step, the material alloy is pulverized by a hydrogen pulverization method. In the second pulverization step, easily oxidized super-fine powder (particle size: 1.0 &mgr;m or less) is removed to adjust the particle quantity of the super-fine powder to 10% or less of the particle quantity of the entire powder.

Abstract: An apparatus for sorting particles. The apparatus includes a magnet mechanism for separating the particles with a magnetic force. The apparatus includes an electric mechanism for separating particles with an electrical force disposed adjacent to the magnet mechanism. The apparatus includes a mechanism for providing the particles to the magnet mechanism and the electric mechanism. The providing mechanism is engaged with the magnet mechanism and the electric mechanism. A method for sorting particles. The method includes the steps of providing the particles to a magnet mechanism and electric mechanism disposed adjacent to the magnet mechanism. Then there is the step of separating the particles with the magnetic force from the magnet mechanism and the electric force from the electric mechanism.

Abstract: A system and method for manipulating magnetic particles in a solution to separate nucleic acid molecules from cell components in a cell solution. The system and method employ a device capable of receiving a plurality of tubes, each of which contain respective sample and paramagnetic particles. The device includes heating and cooling devices to facilitate a lysing step to release the nucleic acid molecules from the cells in the cell solution. The device further includes moveable magnets which can be moved proximate to and away from the tube to hold the paramagnetic particles to which the nucleic acid molecules become bound, so that the molecule-bound particles can be separated from the remainder of the solution, and washed as appropriate. The system also employs an electromagnet which is capable of demagnetizing the particles to allow the particles to freely mix with solution, such as elution solutions which are used to unbind the molecules from the particles.

Abstract: Polymer particles are formed containing molecular memory recognition sites and magnetically susceptible components. The particles are prepared by co-polymerizing one or more monomers and a cross-linking agent in the presence of at least one imprint molecule and at least one magnetically susceptible component such as iron oxide or nickel oxide, and removing the imprint molecule to form molecular memory recognition sites. The particles are also prepared by co-polymerizing the monomer and cross-linking agent in the presence of the imprint molecule to produce particles, removing the imprint molecule and associating magnetically susceptible components with the particles. The particles may also be prepared containing selective adsorbents such as cells or antibodies. The particles are used for selective adsorption of a product such as separating and resolving two different enantiomeric forms due to one of the forms adsorbing to a memory recognition site created by using the form as an imprint molecule.

Abstract: A conveyor system for conveying items, such as bottles and cans, from a first position whereat they are magnetically encoded by using magnetic energy and wherein the coded item is detected at a spaced apart second position using a magnetic sensing device such as a Hall effect sensor. The magnetic encoder can place different levels of magnetism on the container caps and the Hall effect device can detect these different levels of magnetism. By using this technique, containers may be divided into different categories by placing different levels of magnetism on them. The Hall effect device can differentiate these different levels of magnetism which allows the system to do selective sorting at the downstream station.

Abstract: The coated roller with permanent identification is characterized in that an externally inducible microtransmitter with a multidigit alphanumerical code is attached at or in the roller core which microtransmitter is not nondestructively removable. Said microtransmitter is preferably resistant to temperatures of up to at least 180.degree. C. and to chemicals.

Abstract: Shredder waste light fraction is converted into injectable material by being comminuted to an appropriate size. The copper and/or silica is then separated by magnetic separation so that the material may be injected into a metallurgical furnace or cement kiln.

Abstract: Provided is a method of making improved brightness kaolin clay from an aqueous kaolin clay slurry in which the primary active dispersant is a weak dispersant, at least including the steps of adding to the kaolin clay an effective magnet enhancer reagent wherein the magnet enhancer reagent comprises an aqueous solution of one or more magnetic oxides and one or more surface active agents; conditioning the kaolin clay; and performing high gradient magnetic separation on the conditioned kaolin clay to produce an improved brightness kaolin clay. The method is also applied to decreasing iron- and/or titania-containing impurities in a clay.

Abstract: A startup method for a fluidized catalytic cracking (FCC) unit operating with a magnetic catalyst separation means is disclosed. Magnetic strength, or separation severity, is maintained or increased until most of the catalyst has passed through the magnetic separation unit. After this point, magnetic flux and/or centrifugal forces, are decreased for lined-out operation. Preferably a MagnaCat.RTM. catalyst separation unit is used for magnetic fractionation of catalyst.

Abstract: A method for removal of magnetic ink from pulp stock formed from xerographic and laser printed paper waste comprising feeding such pulped paper waste past one or more magnets for removal of all or substantially all of such magnetic ink. The magnetic ink can be removed by capture or deflection techniques. The preferred pulp slurry has a concentration of 4% or less by weight pulp. The preferred magnetic force to be applied utilizes background magnetic fields in excess of 2000 Gauss and a field gradient in excess of 500 Gauss/cm. Also, a method for improving the recyclability of paper waste having ink thereon which does not normally contain a magnetic component, by utilizing one or more magnetic carriers in the formulations of the printing ink utilized.

Abstract: An improved cell separator is provided that includes apparatus for automatically controlling the cell separation process. Particularly, a plurality of valves are responsive to a data processor assembly for controlling the path of fluid flow through the cell separator. A plurality of sensors are provided for providing sensor signals indicative of the density of fluid flowing through the cell separator. The microprocessor is responsive to the sensor signals for controlling the flow and operation of the cell separator. A parastaltic pump is responsive to the microprocessor assembly for controlling the speed and direction of fluid flow through the system. A stirplate assembly is responsive to a drive signal from the data processor assembly for controllably agitating the contents of a column. The data processor assembly is further responsive to the sensor input to provide the valve control signals and pump control signal to control the concentration of selected cells that are collected.

Abstract: A process for removing iron impurities, inter alia iron or iron compounds, from petroleum oil distillation residues is disclosed in which a high gradient magnetic separator incorporates a pack of ferromagnetic fillers in the form of a generally flat or curved sheet-like strip. The ferromagnetic filler is a Fe--Cr alloy of a selected composition and the strip is of selected geometric characteristics such that the rate of removal of iron impurities can be maintained substantially at a maximum throughout the separation mode of operation prior to and after washing of the ferromagnetic filler.

Abstract: A process of separating actinide-containing components from an admixture including forming a slurry including actinide-containing components within an admixture, said slurry including a dispersion-promoting surfactant, adjusting the pH of the slurry to within a desired range, and, passing said slurry through a pretreated matrix material, said matrix material adapted to generate high magnetic field gradients upon the application of a strong magnetic field exceeding about 0.1 Tesla whereupon a portion of said actinide-containing components are separated from said slurry and remain adhered upon said matrix material is provided.

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: A tub grinder for grinding waste material is disclosed. The tub grinder includes a cylindrical tub member having an open end for receiving waste material to be ground. The tub member includes a cylindrical interior wall having one or more magnets mounted thereon for extracting tramp iron from waste material in the tub member.

Abstract: By continuously or intermittently adding amounts of magnetically active moieties, e.g. iron compounds, over time so that the moiety deposits on a catalyst or sorbent in a fluid catalytic cracker or similar circulating hydrocarbon conversion unit, older catalyst, being more magnetic, can be readily separated from catalyst which has been in the system a shorter time. Separation is readily accomplished by passing the catalyst and/or sorbent through a magnetic field and discarding the more magnetic 50% by wt. or more preferably 20% by wt., while recycling the remainder back to the hydrocarbon conversion unit.

Abstract: Apparatus and method for the manufacture of improved abrasive tools and the like which includes apparatus and a method for the creation of a structurally viable matrix having a pattern of abrasive elements which can be shaped, cut and positioned for permanent disposition on a rigid tool body. The apparatus includes a transversely magnetized base surface with magnetic protrusions to provide a mosaic-like surface. A release layer is placed over the protrusions and magnetizable abrasive particles are diffused onto the surface of the release mechanism. The particles orient themselves magnetically to form generally conic stacks which having a stack axis and a distal working portion. The stacks define a working surface which is then coated with acrylic paint to provide structural integrity. Prior to solidification of the paint the cones may be shaped, for example, by passing a magnet near them.

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: This invention relates to an improved catalytic process for carrying out heavy hydrocarbon conversion, usually, but not necessarily, in the presence of nickel and vanadium on the catalyst and in the feedstock, by catalytic cracking gas oils and heavy carbometallic oils to lighter molecular weight fractions. The process is facilitated by the continuous addition of one or more heavy rare earth additives, including gadolinum, terbium, dysprosium, holmium, erbium, and thulium, all having exceptionally high paramagnetic properties, which as they accumulate on aged catalyst, are used to achieve enhanced magnetic separation of aged catalyst. These additives are unusual in that they not only act dramatically as magnetic hooks to assist in removing old, nickel and vanadium poisoned catalyst, but also act to achieve increased activity and improve selectivity of the remaining catalyst, and of equal importance, tend to resist catalyst deactivation.

Abstract: An invention is described in which a method and apparatus are disclosed for guiding, trapping, concentrating and separating particles. The method comprises containing particles in a gas, liquid, or other fluid medium, projecting a beam of light into the particles, inducing the beam of light to impart a spinning motion to the particles, generating a field density gradient in the fluid medium thereby trapping the particles in the beam of light, guiding the particles on the beam of light, concentrating the particles at a focal plane of the beam, and if desired, separating the particles into groups by size and density. Particles are caused to spin and interact with the energy gradient of the beam of light, causing them to orbit in a controlled manner. A preferred apparatus utilizes a chamber, a switching mechanism under a vacuum or partial vacuum, a light source such as a laser or a plurality of lasers, and a lens or a plurality of lenses may be used.

Abstract: A process of selectively agglomerating coal in an aqueous environment while leaving the mineral matter dispersed has been developed. This process is autogenous for hydrophobic particles in that neither an agglomerating agent nor an electrolytic coagulant is needed. It is based on the finding that hydrophobic particles are pushed against each other by the surrounding water structure. This process, which is referred to as selective hydrophobic coagulation, is driven by the so-called hydrophobic interaction energy, which is not included in the classical DLVO theory describing the stability of lyophobic suspensions. The relatively small coagula formed by the selective hydrophobic coagulation process can be readily separated from the dispersed mineral matter by several different techniques such as screening, elutriation, sedimentation and froth flotation.

Abstract: One embodiment is an improved process for economically converting carbo-metallic oils by means of catalytic particulates into lighter products, wherein a portion of the particulates is withdrawn and passed through a high strength magnetic field of at least 1 KG and field grandients of at least 10 KG/inch while conveyed on an electrostatic conducting belt to enable separation of the mass of particulates by inertia into at least two fractions; one of which has, in the case of catalyst, higher activity and lower metals content and is recycled back to the unit; a second higher metals, lower activity catalyst which is disposed of or treated for recovery of metals; and optimally, intermediate fraction which can be disposed of, or first treated to remove metals, and then chemically reactivated and returned to the unit.

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: By continuously or intermittently adding amounts of magnetically active moieties, e.g. iron compounds, over time so that the moiety deposits on a catalyst or sorbent in a fluid catalytic cracker or similar circulating hydrocarbon conversion unit, older catalyst, being more magnetic, can be readily separated from catalyst which has been in the system a shorter time. Separation is readily accomplished by passing the catalyst and/or sorbent through a magnetic field and discarding the more magnetic 50% by wt. or more preferably 20% by wt., while recycling the remainder back to the hydrocarbon conversion unit.

Abstract: The impurity laden particulate material to be cleaned by a gravity feed deduster is passed through a magnetic field of varying intensity to neutralize the static charge causing the impurities to adhere to the primary product. The material is then subjected to air flows to separate the neutralized debris from the primary product. The air flows can be of high velocity and can be either pressurized air or vacuum induced. The cleaned product is collected and the contaminated air is treated to recover the debris therefrom.

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: A process is taught for preparing a coal substitute of low ash level from a composite of coal, mineral matter and pyritic sulfur comprising comminuting the coal composite in an aqueous medium to a size range which promotes the liberation of the mineral matter; subjecting the resulting slurry to fines agglomeration in the presence of a water-insoluble bridging organic liquid; separating the agglomerates from the liquid phase containing the bulk of the mineral matter and a portion of the pyritic sulfur; treating the coal fines by stripping the organic liquid from the fines surface; and redispersing the fines in an aqueous medium having a surface active agent to yield a high solids coal fines slurry so to permit magnetic separation of residual pyritic sulfur and other magnetic mineral matter.

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 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: 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: A method for increasing the magnetization of pyrite-containing pulverized coal comprises heating the coal in an atmosphere of inert gas, desirably nitrogen, containing 3 to 60 torr, preferably 12 to 16 torr, partial pressure of air to a temperature in the range 390.degree. to 455.degree. C., desirably 400.degree. to 410.degree. C., for a time sufficient, preferably 2 minutes to 2 hours, for converting enough pyrite to magnetite to allow separation of at least 50% by weight of the pyrite from the coal in a low-strength magnetic field. The sulfur content of coal treated in accordance with this method can be reduced by subjecting the treated coal to a low-strength magnetic field for moving at least 50% by weight of the pyrite from the coal although a smaller fraction, about 5 to 25%, of the pyrite is actually converted to magnetite.

Abstract: Method of producing silicon carbide and of automatically separating a high grade fraction thereof using magnetic separation techniques. In the method of the invention, a silicon source, a carbon source and a ferromagnetic element source are admixed and the admixture is heated from the center outward to form a cylinder containing silicon carbide with a center to exterior temperature gradient. The ferromagnetic element migrates from the hotter center to the cooler exterior portions of the cylinder. The cylinder is cooled and crushed. The lower grade silicon carbide particles are then separated from the high grade silicon carbide crystals using magnetic separation means.

Abstract: A method for mineral upgrading or concentration, characterized in that a gangue-associated mineral having a hydrophobic surface and being in particulate form, is contacted with particles of a magnetic material also having a hydrophobic surface, whereby the mineral particles become attached to the surface of the magnetic particles, the magnetic particles with the attached mineral particles are separated from the gangue by magnetic means, and the mineral particles are then detached from the magnetic particles.

Abstract: By continuously or intermittently adding amounts of magnetically active moieties, e.g. iron compounds, over time so that the moiety deposits on a catalyst or sorbent in a fluid catalytic cracker or similar circulating hydrocarbon conversion unit, older catalyst, being more magnetic, can be readily separated from catalyst which has been in the system a shorter time. Separation is readily accomplished by passing the catalyst and/or sorbent through a magnetic field and discarding the more magnetic 50% by wt. or more preferably 20% by wt., while recycling the remainder back to the hydrocarbon conversion unit.