Hello, my partner! Let's explore the mining machine together!

[email protected]

megnatic separation

magnetic separation - an overview | sciencedirect topics

magnetic separation - an overview | sciencedirect topics

Magnetic separations take advantages of natural magnetic properties between minerals in feed. The separation is between economic ore constituents, noneconomic contaminants and gangue. Magnetite and ilmenite can be separated from its nonmagnetic RFM of host rock as valuable product or as contaminants. The technique is widely used in beneficiation of beach sand. All minerals will have one of the three magnetic properties. It is ferromagnetic (magnetite, pyrrhotite etc.), paramagnetic (monazite, ilmenite, rutile, chromite, wolframite, hematite, etc.) or diamagnetic (plagioclase, calcite, zircon and apatite etc.). Commercial magnetic separation units follow continuous separation process on a moving stream of dry or wet particles passing through low or high magnetic field. The various magnetic separators are drum, cross-belt, roll, high-gradient magnetic separation (HGMS), high-intensity magnetic separation (HIMS) and low-intensity magnetic separation (LIMS) types.

Drum separator consists of a nonmagnetic drum fitted with three to six permanent magnets. It is composed of ceramic or rare earth magnetic alloys in the inner periphery (Fig. 12.34). The drum rotates at uniform motion over a moving stream of preferably wet feed. The ferromagnetic and paramagnetic minerals are picked up by the rotating magnets and pinned to the outer surface of the drum. As the drum moves up the concentrate is compressed, dewatered and discharged leaving the gangue in the tailing compartment. The drum rotation can be clockwise or counterclockwise and the collection of concentrate is designed accordingly. Drum separator produces extremely clean magnetic concentrate.

Cross-belt separator consists of a magnet fixed over the moving belt carrying magnetic feed (Fig. 12.35). The magnet lifts the magnetic minerals and puts across the field leaving the gangue to tailing. The system is widely used in mineral beach sand industry for separation of ilmenite and rutile. However, it is replaced by rare earth role magnetic and rare earth drum magnetic separators.

Carrier magnetic separation has been proposed for more effective separation of water and solids from acid mine water to generate very pure water (Feng et al., 2000). As discussed in Chapter 10, dissolved heavy metals like zinc and copper can be recovered from acid mine drainage (AMD) by selective precipitation controlling the pH for the precipitation of specific metals. Following this recovery step, the remaining solution is treated with lime to a pH ~12 to precipitate the residual metal ions. The water thus produced is satisfactory for recycling in mineral processing, but not of the quality for domestic use as it still contains some heavy metal ions. That is because, some of the metal hydroxides are amphoteric and their hydroxides re-dissolve at very high pH. For example, the concentration of lead ion increases from nearly zero at pH 9 to 0,12mg/L at pH 12 as the precipitated lead hydroxide dissolves producing plumbate:

Magnetic filtration has been applied in place of lime treatment by Feng and coworkers (2000). Ultrafine magnetic particles are used as magnetic seeds. At a dosage of 0.5 g/L magnetite, all fine precipitate flocs can be rendered strongly magnetic. The mine water is treated with hydrogen peroxide (to oxidize ferrous iron and manganese), followed by the addition of lime and magnetite to raise the pH to 5, Sodium sulfide and more lime are then added to raise the pH to 8. The heavy metal sulfide precipitates are filtered magnetically using a high gradient magnetic separator with a permanent magnetic assembly. This produces an effluent with heavy metal ion (Cu, Zn, Pb, Cd, Cr, Mn, Ti,) well below the discharge limits. The effluent thus freed from heavy metals is then passed to an ion exchange step, where the calcium ion is removed by a cationic resin and sulfate ions by an anion exchange resin. In the elution step, the cation resin is treated with sulfuric acid and the anion resin is treated with sodium hydroxide and lime. High quality gypsum (calcium sulfate) is produced by both elutions. This is a useful byproduct, which helps to offset the cost of the process for the effective removal of toxic metal ions.

A similar process to separate various metal ions in acid mine water by magnetic seeds has been described by Choung and coworkers (2000). In their laboratory study the metal ions are precipitated as hydroxides and magnetite is added as a magnetic seed. The metal hydroxide precipitates are thought to be locked by the magnetic seed, which is then separated by a hand magnet.

The technique has so far been demonstrated only on a laboratory scale. While it may have considerable potential in removing toxic metals from relatively dilute streams of acid mine water, it has not been applied on a pilot plant scale. Economic factors, in particular, the quantity of magnetite required for large scale treatment is an important factor to be considered.

Lyman and Palmer (1993b) studied the roasting(magnetic separation or selective leaching process). The roasting here aimed at oxidizing neodymium while leaving iron as metallic form at a controlled H2water vapor mixture on the basis of the thermodynamic consideration showing a common stability region of Nd2O3 and Fe. Although selective roasting was successful, the subsequent process such as magnetic separation and acid leaching were not because of the extremely fine grain size of the oxidized scrap. Thus, they discontinued the study in this direction and changed the strategy to total dissolution process as has been described previously.

When large quantities of ferrous scrap are to be separated from other materials magnetic separation is the obvious choice. The two types of magnets are permanent magnets and electromagnets. The latter can be turned on and off to pick-up and drop items. Magnetic separators can be of the belt type or drum type. In the drum a permanent magnet is often located inside a rotating shell. Material passes under the drum on a belt. A belt separator is similar except that the magnet is located between pulleys around which a continuous belt travels. Magnetic separation has some limitations. It cannot separate iron and steel from nickel and magnetic stainless steels. Also, composite parts containing iron will be collected which could contaminate the melt. Hand sorting may be used in conjunction with magnetic separation to avoid these occurrences. (See Chapter 3 for discussion of magnetic separation techniques).

Nickel is mainly extracted from its sulfide ores which are concentrated by magnetic separation and a froth flotation process. After concentration by these processes the concentrated ore is mixed with silica and subjected to a number of roasting and smelting operations. During these operations the iron and sulfide contents are reduced by their conversion first into oxide and then to silicate, which is then removed as slag. The resulting matte of Ni3S2 and Cu2S is allowed to cool for few days, when Ni3S2, Cu2S, and nickel/copper metal form distinct phases which can be separated mechanically. The metal is obtained from the matte electrolytically by casting it directly as an anode with a pure nickel sheet as a cathode and aqueous NiCl2, NiSO4 as an electrolyte. At a temperature of around 50C and at atmospheric pressure, the obtained nickel, which is impure, is then reacted with the residual carbon monoxide to produce the volatile nickel tetra carbonyl which gives back the pure metal and carbon monoxide at 230C.

Adsorption using magnetic adsorbents has emerged as an exigent water remediation technology particularly for wastewater treatment while eliminating filtration shortcomings of nonmagnetic adsorbents. Magnetic separation not only simplifies isolation but also opens the ground for easy washing followed by redispersion. Moreover, mechanisms controlling the adsorption process are also enhanced. Pyrolysis, coprecipitation, and calcination are the methods frequently used for preparation of good-quality and high yield of magnetic biochar (Thines et al., 2017).

Conventional heating and microwave-assisted heating have been used in laboratory scale to generate magnetic biochar adsorbents. Conventional pyrolysis has been successfully integrated in industrial production of magnetic biochars using modified furnace. Cottonwood, pinewood, date pits, pine needles, hydrochar waste, orange peels, and pine bark underwent conventional pyrolysis after being treated with magnetic precursors like FeCl36H2O, Co(NO3)26H2O, natural hematite, Fe(NO3)39H2O, etc., to create magnetic biochars (Yang et al., 2016; Zhu et al., 2014; Zahoor and Ali Khan, 2014; Harikishore Kumar Reddy and Lee, 2014; Wang et al., 2015c; Zhang et al., 2013a,d; Theydan and Ahmed, 2012; Chen et al., 2011a; Liu et al., 2010). All these magnetic biochars used for adsorption of phosphate, arsenate, methylene blue, aflatoxin B1, triclosan, Cd2+, Pb2+, and metallic Hg showed improved performance in magnetic response and adsorptive removal from aqueous phase due to incorporation of the more active sites required for adsorption and enhanced physical properties. This can be attributed to uniform and dispersive reinforcement of -Fe2O3, Fe3O4, and CoFe2O4 forming strong mechanical bonds with biochar matrix. The oxide particles embedded showed particle size within 20nm to 1m with variable shapes such as cubic or octahedral. However, reduction in surface area (Wang et al., 2015c; Zahoor and Ali Khan, 2014; Chen et al., 2011a) and lowered adsorption capacity upon reinforcement of magnetic oxide (Khan et al., 2015) did not appear significant indicating minimum hindrance in adsorptive removal of pollutants by these composites.

Microwave-assisted pyrolysis has also found its way in the production of magnetic biochars from bamboo and empty fruit branch used for the remediation of Cr(VI), Cd2+, methylene blue, and Pb2+ from aqueous phase (Ruthiraan et al., 2015; Mubarak et al., 2014; Zhang et al., 2013d; Wang et al., 2013, 2012, 2011). These magnetic biochars containing hydrous Fe2O3, cobalt oxide, binary CoFe oxide, and metallic Ni crystals adsorbed these contaminants through electrostatic attraction, ion exchange, inner sphere surface complexation, and physisorption. Superparamagnetic cotton fabric biochars were obtained following both conventional pyrolysis and microwave-assisted pyrolysis by ZHu et al. (2014) in order to compare their properties. The authors found that microwave-heated biochar showed no apparent agglomeration and was characterized by more controlled size and dispersion of oxide particles. Modification of magnetic biochar to further improve its functionality has also been reported. For example, chitosan modification of magnetic biochar obtained from invasive species Eichhornia crassipes provided more oxygenated functional groups for greater electrostatic interaction and therefore enhanced Cr(VI) remediation (Zhang et al., 2015a).

Coprecipitation is another process by which magnetic biochar can be fabricated. Yu et al. (2013) employed sugarcane bagasse as the raw material for the production of magnetic-modified sugarcane bagasse through the chemical precipitation of Fe2+ and Fe3+ over the sugarcane bagasse particles in an ammonia solution under ultrasound irradiation at 60C. A large amount of carboxyl groups found on the surface of biochar, which made the surface more negatively charged. Thats why better adsorption was found for the removal of Pb2+ and Cd+ due to the ion-exchange mechanism (Yu et al., 2013). A comparison of two synthesis methods including chemical coprecipitation of iron oxides onto biochar after pyrolysis and chemical coprecipitation of iron oxides onto biomass before pyrolysis for preparing magnetic biochars was studied by Baig et al. (2014). The results suggested that the chemical coprecipitation of iron oxides before pyrolysis led to greater Fe3O4 loading, higher saturation magnetization, improved thermal stability, and superior As(III, V) adsorption efficiency of the biochars (Baig et al., 2014).

Magnetization in biochar can also be introduced via calcination in which biochar is subjected to heat treatment to remove water and drive off CO2, SO2, and other volatile constituents. The simplicity of this process was the main reason behind the wide application of this process in the production of magnetic biochar composites. For instance, calcination of rice hull and ferric acetylacetonate in tube furnace generates magnetic biochar consisting of good dispersion of Fe3O4 particles on the surface. The biochar showed improved lead removal performance through hydroxide precipitation followed by suitable magnetic separation.

Magnetic mineral separation techniques are invariably selective, and not fully representative of the grain size and composition of magnetic minerals present in the sample; however, magnetic separation may be necessary for SEM/TEM, X-ray, Mossbauer, or chemical analyses. The importance of fine SD grains as remanence carriers emphasizes the necessity of making the separation technique as sensitive as possible to the fine grains. As grain shape has become an important criterion for distinguishing detrital and biogenic magnetite, separation procedures to prepare representative extracts for SEM and TEM observation have become more important. A recommended procedure which has been successful for extracting magnetite (including the SD fraction) is as follows: (i) Crush the sample (if necessary) in a jaw crusher with ceramic jaws, (ii) Use a mortar and pestle to produce a powder. (iii) Dissolve carbonate with 1N acetic acid buffered with sodium acetate to a pH of 5, changing the reagent every day until reaction ceases (several weeks), (iv) Rinse the residue with distilled water, (v) Agitate the residue ultrasonically in a 4% solution of sodium hexametaphosphate to disperse the clays. (vi) Extract the magnetic fraction using a high-gradient magnetic separation technique (Schulze and Dixon, 1979), or alternatively, pass the solution (several times, if necessary) slowly past a small rare earth magnet.

Seed receipt and preparation: Following receipt, the seeds are sent for mechanical preparation. This consists of mechanical screening and magnetic separation to remove any impurities which may be present. Following separation are the processes of crushing, flaking, and cooking.

Oil Extraction: The prepared seeds are mixed with hexane in a continuous counter current system to produce a hexane-oil mixture (miscella) and seed cake. The seed cake is separated from the miscella, dried cooled, pressed, and used to produce animal feed. The hexane is recovered from the miscella under vacuum (using direct and indirect steam) and reused in the system. The remaining crude oil is then cooled and sent for refining.

Oil refining packaging: Crude oil and ghee are processed using the following steps:Degumming (for sunflower seeds or soybean) and neutralization gums are removed in a batch process, using phosphoric acid. Neutralization is done by adding caustic soda to remove free fatty acids from crude oil to produce semi-refined oil.Bleaching color is removed from the oil using fuller's earth followed by filtration.Deodorization unpleasant odours are removed from oil by high temperature vacuum distillation.Packaging the reined, bleached, and deodorized (RBD) oil is bottled in automatic filling lines.

Degumming (for sunflower seeds or soybean) and neutralization gums are removed in a batch process, using phosphoric acid. Neutralization is done by adding caustic soda to remove free fatty acids from crude oil to produce semi-refined oil.

Soap and glycerin production: Fats are saponified in a batch process, by mixing with caustic soda and heating with direct and indirect steam. After saponification, soap is separated from the lye solution to be dried, blended with additives, homogenized, cut, and pecked. Glycerin is separated from the lye solution and distilled.

The two main sources of energy are mazot and electricity. Mazot and solar are used in the boilers to generate steam. Average annual consumption 15,000 tons of mazot and 600 tons of solar. Annual electricity consumption is around 10.5 million kWh.

The factory consumes an average of 16,800 m3/day of water of which 1,800 m3/ day is process water, and 1,500 m3/day cooling and vacuum water. This water is taken entirely from group water boreholes within factory premises. Approximately 35 m3 of drinking water is taken from the public network every day.

The factory generates about 16,000 m3/day of industrial wastewater from different factory steams, including process effluents, boiler blow down, cooling water, vacuum water, and steam condensate. The wastewater is discharged to Akhnawy drain near the factory.

Iron-containing residues generated in steel plants contain several toxic elements and require further processing In an integrated process described by Eetu-Pekka and coworkers (2005) the residues go through a magnetic separation step. In the second stage they are agglomerated, before the reduction of iron oxides. The element, which is most problematic is sulfur. Some of it is transferred in to the gas phase during reduction as hydrogen sulfide and carbonyl sulfide (COS). There would still be a large amount of sulfur in the residue after the reduction phase. One way to decrease the amount of sulfur is to separate the residues with high sulfur content before the processing and leave them outside of recycling. Other possible methods suggested are to enhance the transfer of sulfur into the slag phase by controlling the slag composition or by ensuring the carbon saturation of iron. The slag composition can be controlled to enhance the transfer of sulfur by addition of lime to the residue material. Excessive lime should be avoided to prevent precipitation of solid phases like dicalcium silicate. Sulfur content of iron can be lowered by increasing the carbon and silicon content in metal, by adding carbon into the residue material. Optimum quantity depends upon the original composition of the residue material. The process is schematically shown in Figure 8.25

MWI-bottom ash is the solid residue from combustion of municipal waste or in a Municipal Waste Incineration Furnace. Often MWI-bottom ashes have been subjected to a post treatment consisting of magnetic separation of iron and sieving and comminution of particles > 40 mm. Fly ashes from Municipal Waste Incineration are kept separate from the MWI-bottom ash. In the Dutch situation it is forbidden to prepare mixed ashes from fly ash and bottom ashes. In 1996 800,000 tons of MWI-bottom ash were produced in the Netherlands. The last years MWI-bottom ash is utilized for 100%, primarily in granular form as embankment material up to a hight of 10 m or more or as a road base material.

MWI-bottom ashes are supplied to the market with a certificate for its technical and environmental behaviour. The environmental part of this certificate is based on old legislation. MWI-bottom ashes up to now always comply with the demands for environmental certification.

The Building Materials Decree enforces more severe demands than the present regulations. Because of that a large part of the MWI-bottom ashes does not comply with the demands from the Building Materials Decree. To safeguard its outlet to the market the Dutch Ministry of the Environment has developed a Special Category for MWI-bottom ashes. In this category MWI-bottom ashes can be utilized under a set of isolation measures. With the Municipal Waste Incineration sector the appointment has been made to pursue steady quality improvement of its byproducts so that MWI-bottom ashes can be utilized as Category 2 Building Materials in future.

what is magnetic separation? (with pictures)

what is magnetic separation? (with pictures)

Magnetic separation is an industrial process where ferromagnetic contaminants are recovered from materials on the production line. Manufacturers use this to extract useful metal, separate recycling, purify materials, and perform a wide variety of other tasks. Manufacturers of magnetic separation equipment may have a range of products available for sale for different applications, including an assortment of sizes with strong and weak magnetic fields to attract different kinds of magnetic material.

The magnetic separator consists of a large rotating drum that creates a magnetic field. Materials enter the separator and fall out through mesh at the base if they are not magnetic. Sensitive particles respond to the magnetism and cling to the sides of the container. The drums can be used in continuous processing of materials as they move along the assembly line, or in batch jobs, where a single batch is run through all at once.

One common use for magnetic separation is to remove unwanted metal from a shipment of goods. Magnetic separation can help companies keep materials pure, as well as remove things like nails and staples that may have crept into a shipment. The equipment can also purify ores, separate components for recycling, and perform a variety of other tasks where metals need to be separated or isolated. Equipment can range in size from a desktop unit for a lab that needs to process small amounts of material to huge drums used in scrap metal recycling centers.

Manufacturers of magnetic separation equipment typically provide specifications for their products for the benefit of prospective customers. Consumers may need equipment that targets a specific range of metals, or could require large size or high speed capacity. It may be possible to rent or lease equipment for some applications, or if a factory wants to try a device before committing to a purchase. Used equipment is also available.

A gentler form of magnetic separation can be used for delicate tasks like removing magnetic materials from cremated remains or finds at an archaeological site. In these situations, a technician carefully moves a magnet over the material to pull out materials like staples and jewelry. At a crematorium, this is necessary before ashes are ground, as metal objects can damage the equipment. For archaeologists, it can provide a mechanism for carefully separating materials at a find and documenting the position and location of various objects as the archaeologist uncovers them on site or in a lab.

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a InfoBloom researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a InfoBloom researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

@allenJo - I do believe they use these systems in water treatment systems. I dont know the mechanisms used but it is used from what Ive heard. Water should give up its magnetic particles quite easily, I would think, since the metals are just floating about like flotsam and jetsam in the ocean.

@Charred - Those are two very good points, and I am sure that they are accounted for. The uses described in the article suggest scenarios where the metals are rather loosely fitting, so I think the cleanup job would be thorough. What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

I see two things here that are necessary for magnetic separation to work well. First, the metals must be easily dislodged from whatever material or goop they happen to be sitting in. Otherwise, theyll just remain stuck, and the separation will be less than effective in pulling out all the metals. Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

magnetic separation | magnetic sorting

magnetic separation | magnetic sorting

Cell separationis a powerful techniqueand an indispensable toolfor basic and clinicalresearchapplications.The heterogeneity of biological cell populations often necessitates separation of individual cell types for deeper investigation. Traditionally, cell separationiscarried out based on the physical properties of cells, such asadherence,size, density oraffinity to electrostatic or magnetic forces. Biochemical characteristics, such as expression of surface antigens, are also used for cell separation.

This cell separation technique utilizes the potential to label cell surface markers with magnetic beadtagged antibodies and the ability of a magnetic field to migrate the labeled particles from a distance.1This controlled migration by a magnetic force (magnetophoresis) is invaluable in separating heterogeneous cell populations and is the basis for magnetic-activated cell sorting (MACS). Cells can be separated by tube-based or column-based methods.2

Positive selectionselects the cells that need to becollected as the target population. The methodusesmagnetic particleswithantibodiestargeting a subpopulation of interestcovalently bound to their surface.Once placed withinthemagnet, targeted cells migrate towardthe magnet and are retained within the magneticfield while the unlabeled cells are drawn offand discarded.The targeted cells can then be collected andused in the desiredapplication after removalfrom the magnetic field.

Positive cell selections yield excellent results with respect to purity, recovery, and viability of selected cells. However, depending on the cell type being selected and the surface antigen being targeted by the particle, positive selections can result in cells becoming activated or otherwise functionally altered. Even though the probability of activation is low, this magnetic particle-induced activation may be an issue if you specifically require purified yet unstimulated cells. In that case, you should consider negative selection for your cell separations.

Inthisprocedure, all unwanted cells are first labeled with a cocktail containing monoclonal antibodies against antigens expressed bythem. After washing away unbound antibody, a second-step reagent is used to magnetically label these cells. The labeled cells migrate to themagnet leavingin suspensiona pure and untouched subpopulation of cells to becollected.Alarge percentage (>95%) of unwanted cell populations can be removedthrough negative selection.1

Enrichment of cells before sorting is very beneficial for obtainingfaster andbetter sorting results, especially for very rare cell populations. In this procedure, the cells of interest are firstenriched through negative selection. The process can remove 2080% of unwanted cells,thusenriching theuntouchedcell population of interestand enabling faster and more efficient cell sorting.

Our portfolio includesa selection ofmagnetic separation reagents for positive and negative selection of cells.Reagentsto enrichB lymphocytes, CD4andCD8 T lymphocytes, NK cells andcertaintypes ofmurine dendritic cells are available.

Expression of activation markers CD25 and CD69 after either positive or negative selection (enrichment) of CD4 T cells using BD IMag Mouse CD4 ParticlesDM and BD IMag Mouse CD4 T Lymphocyte Enrichment SetDM, respectively.

Demonstration of how the basic enrichment protocol can be manipulated for different experimental needs and how positive selections can be coupled with enrichments to isolate uncommon cell subpopulations.

This form is intended to help us improve our website experience. For other support, please visit our Contact Us page.

magnetic cell separation | cell isolation technology

magnetic cell separation | cell isolation technology

Your shopping cart contains an active quote order and cannot be modified.To modify your shopping cart, please remove the current quote order before making changes to your cart. If you require changes to the quote, please contact your local sales representative.

Magnetic cell separation, also known as immunomagnetic cell separation or magnetic cell sorting, involves targeting cells for selection or depletion using antibodies or ligands directed against specific cell surface antigens. Labeled cells are cross-linked to magnetic particles, also known as magnetic beads, that can be immobilized once an electromagnetic field is applied.

Both positive and negative selection can be performed using magnetic cell isolation methods. When a positive selection is performed, the supernatant can be discarded and the magnetically-labeled cells of interest remain immobilized until removed from the electromagnetic field. When a negative selection is performed, the desired cells are located in the supernatant.

Column-based magnetic cell separation techniques involve passing a sample previously labeled with magnetic particles through a column matrix within a magnetic field. The column is filled with ferromagnetic spheres that become magnetized in the applied magnetic field, creating a localized magnetic field that can immobilize the magnetic particles within the sample. When positive selection is used (Figure 2), non-magnetically-labeled, non-target cells can pass through the column while magnetically-labeled, target cells are retained within the column. Upon removing the external magnetic field, the target cells can be collected by pushing buffer through the column.

While commonly-used, column-based magnetic cell isolation protocols can sometimes be costly, complicated, laborious, and time-consuming, requiring multiple washes to avoid contamination between separations and the use of new columns for each experiment. In addition, its not uncommon for columns to become clogged, risking the loss of precious samples, especially when working with tissue samples that contain a significant amounts of debris.

Column-free magnetic cell separation techniques involve placing a tube filled with a magnetically-labeled sample within a magnetic field. The magnetically-labeled target cells will migrate towards the magnet and will be immobilized at the sides of the tube. The unlabeled cells in suspension can then be poured or pipetted off to separate them from the labeled cells. Upon removing the tube from the magnet, the labeled cells are released from the sides of the tube. If a positive selection protocol is used (Figure 3), the labeled cells are the cells of interest and can be resuspended in buffer for immediate use in downstream applications.

Which method should you choose? In general, column-based and column-free technologies are both well-established methods that result in highly purified cells. Both technologies have been used by life science researchers for more than 20 years in a variety of applications and with thousands of citations in peer-reviewed publications. In an increasingly competitive research environment, we recommend choosing the most efficient technologies available to help you complete your cell separationand, ultimately, your downstream experimentsin less time and with less effort. In our experience, column-free magnetic cell isolation techniques are the most efficient approaches to isolate highly purified cells for research.

Magnetic cell sorting and fluorescence-activated cell sorting (FACS) are the two most common ways by which scientists isolate specific cell types. The choice between the two methods depends on what you require for your specific downstream application.

Magnetic cell isolation is a much faster and simpler procedure than FACS, and is often the preferred cell isolation method for common cell types. However, unlike magnetic cell isolation, FACS will allow you to:

To decide which of the two methods to use, start by investigating whether the expected purity of available magnetic cell isolation kits would meet your experimental needs. Product performance data can often be found on a suppliers website. If a vendor does not publicly provide performance data for their cell separation products, contact them directly to ask for this information or ask for a sample of their product to test in your own lab. Due to their speed and simplicity, magnetic cell isolation techniques can often be easier to incorporate into your experimental design than complicated flow sorting instruments and protocols. Magnetic cell separation techniques and FACS can also be used together. Pre-enriching your sample with magnetic cell separation techniques prior to FACS can maximize yield and purity and reduce sort time, especially when working with large sample volumes or rare cell types.

Automating magnetic cell separation can save hands-on time for labs that routinely perform magnetic cell separation procedures. In addition, automation minimizes handling of potentially hazardous samples, which may be important to reduce the risk of exposure to dangerous pathogens.

StemCell Technologies Inc. and affiliates ("STEMCELL Technologies") does not share your email address with third parties. StemCell Technologies Inc. will use your email address to confirm your identity and send you newsletters, transaction-related emails, promotional and customer service emails in accordance with our privacy policy. You can change your email preferences at any time.

magnetic separation

magnetic separation

Including wet high intensity, induced roll, rare earth roll, rare earth drum, low intensity and medium intensity magnetic separators the Reading range has a magnetic solution to fit your particular processing requirements.

The WHIMS range includes 4, 16, 24 and 48 pole machines with either 68 or 120 millimetre separation matrix widths. WHIMS separators are suitable for applications requiring higher magnetic field gradients to remove weakly magnetic particles from non-magnetic concentrates. Nominal capacities range from 6 to 150 tonnes per hour.

Reading induced roll and semi-lift induced roll magnetic separators are available with 2 starts, single or twin-pass configurations in 133 millimetre roll diameter and 760 millimetre roll width or 160 millimetre roll diameter and 1000 millimetre roll width, and deliver nominal capacities of up to 12 tonnes per hour. Pilot roll laboratory scale separators are available in both induced roll and semi-lift induced roll configurations.. Typical applications include:

The rare earth magnetic separator range achieves the most effective dry separation of paramagnetic minerals at high throughput rates. The range includes Rare Earth Roll (RERS) and Rare Earth Drum (REDS) Separators which are available in a range of configurations and sizes from lab units to full production units.

magnetic separators

magnetic separators

The science of magnetic separation has experienced extraordinary technological advancements over the past decade. As a consequence, new applications and design concepts in magnetic separation have evolved. This has resulted in a wide variety of highly effective and efficient magnetic separator designs.

In the past, a process engineer faced with a magnetic separation project had few alternatives. Magnetic separation was typically limited and only moderately effective. Magnetic separators that utilized permanent ferrite magnets, such as drum-type separators, generated relatively low magnetic field strengths. These separators worked well collecting ferrous material but were ineffective on fine paramagnetic particles. High intensity magnetic separators that were effective in collecting fine paramagnetic particles utilized electromagnetic circuits. These separators were large, heavy, low capacity machines that typically consumed an inordinate amount of power and required frequent maintenance. New developments in permanent magnetic separation technology now provide an efficient alternative for separation of paramagnetic materials.

Technological advances in the field of magnetic separation are the result of several recent developments. First, and perhaps most important, is the ability to precisely model magnetic circuits using sophisticated multi-dimensional finite element analysis (FEA). Although FEA is not a new tool, developments in computing speed over the last decade have made this tool readily accessible to the design engineer. In this technique, a scaled design of the magnetic circuit is created and the magnetic characteristics of the individual components quantified. The FEA model is then executed to determine the magnetic field intensity and gradient. Using this procedure, changes to the magnetic circuit design can be quickly evaluated to determine the optimum separator configuration. This technique can be applied to the design of both permanent and electromagnetic circuits. As a consequence, any type of magnetic separator can be developed (or redesigned) with a high level of confidence and predictability.

Equally important has been the recent development of rare-earth permanent magnets. Advances in rare-earth magnet materials have revolutionized the field of magnetic separation. The advent of rare-earth permanent magnets in the 1980s provided a magnetic energy product an order of magnitude greater than that of conventional ferrite magnets. Rare-earth magnetic circuits commonly exhibit a magnetic attractive force 20 to 30 times greater than that of conventional ferrite magnets. This development has provided for the design of high-intensity magnetic circuits that operate energy-free and surpass the strength and effectiveness of electromagnets.

Finally, the materials of construction used in the fabrication of magnetic separators have advanced to a point that significantly extends service life while decreasing maintenance. Advanced materials, such as fiber composites, kevlar, ultra high molecular weight polyester, and specialty steel alloys are now commonly used in contact areas of the separator. These materials are lightweight, abrasion resistant, and comparatively inexpensive resulting in significant design advantages as compared to previous construction materials.

The evolution of high strength permanent rare-earth magnets has led to the development of high-intensity separators that operate virtually energy free. The use of rare-earth magnetic separators for beneficiation of industrial minerals has become the industry standard with literally hundreds of separators placed in recent years. The following sections present an overview of the most widely used permanent magnetic separators: rare-earth drum and rare-earth roll-type separators.

Of the roll separators, there are at least fourteen manufacturers. Most of the different makes are based on the original Permroll design concept originated by this author. Various enhancements have been mainly focused on the belt tracking methods. New magnetic roll configurations and optimization of roll designs are relatively recent innovations. Additional optimization efforts are in progress.

At last count, seven manufacturers have commercially available drum separators, most based on magnet circuits derived from the use of conventional ferrite magnet. Two unique designs have been developed with one clearly offering advantages over older configurations.

Rare-earth elements have some unique properties that are used in many common applications, such as TV screens and lighters. In the 1970s, rare-earths began to be used in a new generation of magnetic materials, that have very unique characteristics. Not only were these stronger in the sense of attraction force between a magnet and mild steel (high induction, B), the coercivity (Hc) is extremely high. This property makes the magnetization of the magnet body composed of a rare-earth element alloy very stable, i.e., it cannot easily be demagnetized.

It was a well known fact that permanent magnets positioned on both sides of a flat steel body can magnetize the steel to a high level, if the magnet poles were the same on each side, i.e., the magnets would repel each other. However, in the past, large magnet volumes were required to achieve any substantial magnetization. With the new powerful magnets, the magnet volume could be relatively small to generate high steel magnetization. In 1981 this author determined the optimum ring size for samarium-cobalt magnets. Maximum steel magnetization (near saturation) could be obtained if the rings were stacked to make a roll using a 4:1 ratio of magnet to steel thickness, see Figure 1. Since magnetized particles are attracted to the magnetized steel surface on the roll periphery, this means that 20% of the exposed roll surface would collect such material. This collection area is an order of magnitude greater than what could be achieved with prior art magnets, making the magnetic roll useful for mineral separation.

Although one of the first prototype rare-earth magnetic rolls was calculated to have about 14,000 gauss steel magnetization, it was found in comparative testing with electromagnetic induced roll (IMR) separators operating at about 21,000 gauss, that similar performance was obtained in fine particle processing (smaller than 1 mm). When processing coarser particles an improved performance was established (e.g., less weakly magnetic contaminants remaining in the upgraded product and fewer separation passes to achieve high quality). The improvement results because the magnetic force acting on the particles is high, due to a high flux gradient. An electromagnetic induced magnetic roll separator has an air gap, which must be increased to accommodate the processing of larger particles. The rare-earth magnetic roll (REMR) magnetic separator has no such air gap. Consequently, the magnetic force does not decline in the manner of an IMR set with a large air gap.

As the name implies, suspended magnets are installed over conveyors to lift tramp iron out of the burden. Suspended magnets have been more frequently applied as conveyor speeds have increased. Suspended type magnets are capable of developing very deep magnetic fields and magnet suspension heights as high as 36 are possible.

Suspended magnets are of two basic types (1) circular and (2) rectangular. Because of cost considerations, the rectangular suspended magnet is nearly always used. Magnet selection requires careful analysis of the individual system to insure adequate tramp iron removal. Factors that must be considered include:

The position in which the magnet must be mounted will also influence the size of magnet required. The preferred position is at an angle over the head pulley of the conveyor where the load breaks open and the tramp iron is free to move easily to the magnet face. When the suspended magnet must be mounted back from the head pulley parallel to the conveyor, tramp iron removal is more difficult and a stronger magnet is required.

Magnetic drum separators come in many different styles. Tramp iron drum separators usually use a magnet design referred to as a radial type. In such a unit the magnet poles alternate across the width of the drum and are of the same polarity at any point along the drums circumference. The magnet assembly is held stationary by clamp bearings and the drum shell is driven around this magnet assembly.

Drum-separators lend themselves to installation in chutes or at the discharge point of bucket elevators or screen conveyors.The capacity and type of tramp iron to be removed will determine the size selection of a drum separator. They are available in both permanent and electro magnetic types.

Standard drum diameters are 30 and 36. General guide lines, in diameter selection, are based on (1) feed volume (2) magnetic loadings and (3) particle size. The 30 diameter drum guide lines are roughly maximum of 75 GPM per foot feed volume, 8 TPH per foot magnetic loading and 10 mesh particle size. The 36 guide lines are 125 GPM per foot feed volume, 15 TPH per foot magnetic loading and 3/8 inch particle size.

For many years, wet magnetic drum separator magnet rating has been on the basis of a specified gauss reading at 2 from the drum face. The gauss reading is an average of readings taken at the centerline of each pole and the center of the magnet gap measured 2 inches from the drum surface. This rating tends to ignore edge of pole readings and readings inside of the 2 inch distance, particularly surface readings which are highly important in effective magnetic performance.

We have previously discussed dry drum separators as used for tramp iron removal. A second variety of drum separator is the alternating polarity drum separator. This separator is designed to handle feeds having a high percentage of magnetics and to obtain a clean, high grade, magnetic concentrate product. The magnet assembly is made up of a series of poles that are uniform in polarity around the drum circumference. The magnet arc conventionally covers 210 degrees. The magnet assembly is held in fixed operating position by means of clamp bearings and the cylinder is driven around this assembly.

Two styles of magnet assemblies are made up in alternating polarity design. The old Ball-Norton type design has from 8 to 10 poles in the 210 arc and develops a relatively deep magnetic field. This design can effectively handle material as coarse as 1 inch while at the same time imparting enough agitation in traversing the magnetic arc to effectively reject non-magnetic material and produce a clean magnetic concentrate product. The 30 diameter alternating polarity drum is usually run in the 25 to 35 RPM speed range.

Application of the high intensity cross-belt is limited to material finer than 1/8 inch size with a minimum amount of minus 200 mesh material. The cost of this separator is relatively high per unit of capacity approaching $1000 per inch of feed width as compared to $200 per inch of feed width on the induced roll separator.

This investigation for an improved separator is a continuation of the previously reported pioneering research of the Bureau of Mines on the matrix-type magnetic separator. When operated with direct current. or a constant magnetic field, the matrix-type magnetic separator has several disadvantages, which include incomplete separation of magnetic and nonmagnetic components in one pass and the retention of some of the. magnetic fraction at the discharge quadrant. Since the particle agitation that results from pulsed magnetic fields may overcome these factors, operation with an alternating current would be an improvement. Another possibility is the separation of dry feeds, which may have applications where the use of water must be avoided.

The effects of an alternating field were first described by Mordey and later by others of whom Doan provides a bibliographical resume. The significant feature to note in the description by Mordey is the change from a repulsion in weak fields to an attraction in strong fields, in addition to a difference in response with different minerals. The application by Mordey was with wet feeds using launders and inclined surfaces, although applications by others are with both wet and dry feeds.

Except for occasional later references the interest in alternating current for magnetic separation has almost disappeared. Lack of interest is probably due to the apparent high power consumption required to generate sufficiently intense magnetic fields, a problem that warrants further consideration.

The matrix separator differed somewhat from the slotted pole type described in a previous report in that the flux passed into the matrix from only one side, the inverted U-shaped magnet cores 4 and 7 illustrated in figure 1. Figure 1 shows a front view, side view, and a bottom view of the matrix-type magnetic separator. By this arrangement, an upward thrust could be exerted on the matrix disk during each current peak; the resulting induced vibration would accelerate the passage of the feed as well as the separation of the magnetic particles from the nonmagnetic particles since the applied field during the upward thrust preferentially lifts

The matrix disk 5 rotates successively through field and field-free quadrants. Where a given point on the disk emerges into a field quadrant, feed is added from a vibrating feeder; nonmagnetic particles fall through the matrix, and magnetic particles are retained and finally discharged in the succeeding field-free quadrant.

Two types of disks were used, a sphere matrix illustrated in top and cross-sectional views in figure 2 and a grooved plate type similarly illustrated in figure 3. Both the spheres and grooved plates were mounted on a nonmagnetic support 1 of optimum thickness for vibration movement (figs. 2-3). The sphere matrix disk, similar to that of the earlier model, had a matrix diameter 8 of 8.5 inches and spokes 7 spaced 45 apart; the spheres were retained by brass screens 4 (fig. 2).

The grooved plate disk was an assemblage of grooved steel plates that tapered so that one edge 5 was thinner than the other 6 (fig. 4) to provide a stack in the form of a circle having an outside diameter 9 of 7.9 inches (fig. 3). The plates were retained by two split aluminum rings 8 and 3 clamped in two places 1 and 11. They were stacked so that the vertically oriented grooves of one plate touched the flat side of the second plate. As illustrated in figure 4, two slots 3 and 4 were added to reduce eddy current losses.

Both disks 5 illustrated in figure 1 were rotated by a pulley 1 through a steel shaft 8 held by two aluminum bars 2 and which in turn were fastened to aluminum bars 3 and steel bars 6. The magnetic cores 4 and 7 were machined from 10- by 12-inch E-shaped Orthosil transformer laminations. For wet feeds,

With the information derived from the performance of this separator, a cross-belt-type separator was also constructed as illustrated in figure 5, which shows a front view and a cross-sectional view through the center of the magnet core. The cross-belt separator mentioned here differs somewhat from the conventional cross-belt separator in that the belt 5 moves parallel to the feed direction instead of 90 with the feed direction. The magnetic core, composed of parts 17, 19, 21 and 22 that were machined from 7--by 9 inch E-shaped Orthosil transformer laminations, supplies a magnetic field between one magnetic pole 6, which has grooves running parallel to the feed direction, and the other magnetic pole 14. Owing to the higher intensity field at the projection from the grooves, magnetic particles are lifted from feeder 15 to the belt 5. By movement on flat-faced pulleys 3 supported by bearings 4 the belt 5 carries the particles to the discharge chute 7. Nonmagnetic particles fall from the feeder edge and are discharged on the chute 8. A special 0.035-inch-thick Macarco neoprene-dacron endless belt permits a close approach of the feeder surface to the magnet pole 6. The feeder 15 constructed of plexiglass to prevent vibration dampening by eddy currents, is fastened to a vibration drive at 16 derived from a small vibrating feeder used for granular materials. A constant distance between poles 6 and 14 was maintained by acrylic plastic plates 9 on each side of the poles 6 and 14 with a recessed portion 13 to provide room for the belt 5 and feeder 15. The structural support for the separator, which consisted of parts 1, 2, 11, 18, and 20, was constructed of 2- by 2- by -inch aluminum angle to form a rectangular frame, and part 10 was machined from angular stock to form a support for the magnet core.

Each U-shaped magnet core in figure 1 was supplied with two 266-turn coils and two 133-turn coils of No. 10 AWG (American wire gage) heavy polythermaleze-insulated copper wire. With alternating current excitation, the current and voltage are out of phase so that the kilovolt-ampere value is very high even though the actual kilowatt power is low. This difference may be corrected with either series capacitors to reduce the input voltage or parallel capacitors to reduce the input current. However, the circuit that was selected is illustrated in figure 6 in which the two 266-turn coils are connected in series with the capacitor 2. Power is supplied by the 133-turn drive coil 7 that is connected in series with the 133-turn drive coil 9 on the other U-shaped magnet core. Coils 4 and 6 and the capacitor 2 form a circuit that resonates at 60 hertz when the capacitor 2 has a value of 49 microfarads in accordance with the equation

For the capacitance in the power input circuit, the value is calculated on the basis of the equality of equations 2-3. When the input at point 10 is 10 amperes at 126 volts or 1.26 kilovolt-amperes, the current at point 3 and the voltage at

point 1 are 10 amperes and 550 volts, respectively, or a total of 11.0 kilovoIt-amperes for the two magnet cores, which provides a 5,320-ampere- turn magnetization current. The capacitors, a standard power factor correction type, had a maximum rating of 600 volts at 60 hertz.

Application of alternating current to the cross-belt separator is not successful. In contrast to the matrix-type separator in which the feed is deposited on the magnetized matrix, the feed for the cross belt is some distance below a magnet pole where the field is weaker and the force is a repulsion. Even though the magnetic force with the matrix-type separator may be a repulsion instead of an attraction, it would result in the retention of the magnetic fraction in the matrix. Replacement of the alternating current with an intermittent current eliminates the repulsion effect but still retains the particle vibration characteristics.

For an intermittent current the circuit shown in figure 7 is used. A diode 5 supplies the current to a coil 4, which can be the magnetizing coil for the cross-belt separator, or for one magnet core of the matrix-type separator that is connected in parallel or series with the coil for the other core. A coil 2 is supplied with half-wave-rectified current from a diode 6 but is out of phase with the other coil 4 and is only applicable to a second separator. However, the circuit illustrates the reduction of the kilovolt-ampere load of intermittent magnetizing currents. As an example, measurements were, made with the two magnet cores of figure 1; each core had 532 turns of wire. When the capacitor 9 has a value of 72 microfarads, the current at point 8 is 13 amperes, and the voltages at points 10, 1, and 7 are 75, 440, and 390 volts, respectively. The kilovoIt-ampere input at point 11 is therefore 0.98, and the kilovolt-amperes supplied to the coils is 5.07. This circuit is not a simple resonance circuit, as shown in figure 6, but a circuit in which the correct value of the capacitor 9 depends on the current. At currents lower than 13 amperes, the 72-microfarad value is too large.

However, separations with intermittent current were confined to a simple one-diode circuit. With the matrix-type separator, each magnet core carried 10.5 amperes at 240 volts through 399 wire turns or a total of 21 amperes since the two cores were connected in parallel. For the cross-

belt separator illustrated in figure 5, five 72-turn coils and one 96-turn coil wound with No. 6 AWG heavy polythermaleze-insulated square copper wire were used in series connection. Current-carrying capacity is approximately 40 amperes with an input of approximately 80 volts of half-wave-rectified 60-hertz current. At 40 amperes, the average number of ampere turns would be 18,240. Intermittent current and voltage were measured with the same dynamometer meters used for alternating current; these meters measure an average value.

It is possible to increase the magnetizing current for the matrix-type separator without excessive vibration by increasing the thickness of the plate 1 (figs. 2-3). Another alternative is a combination of intermittent and constant magnetic fields. Although a variety of circuits are possible, the combination of fields was accomplished with the simple adaptation of the stray field losses in a U-shaped magnet core using the circuit of figure 8. The power drawn is full-wave rectification, or half wave for each leg of the magnet core with the flux, from the coils 3 and 4 adding. Owing to magnetic leakage, the flux from the coil nearest to the magnet pole tested predominates. When the magnetic field is measured with a Bell model 300 gaussmeter and observed with a Tektronix type 547 oscilloscope with a type 1A1 amplifier, the results of figure 9 represent a pulsating magnetic field on top of a constant magnetic field plateau.

Although it is known that minerals in water suspension may be separated in the constant-field matrix-type separator at fine sizes, some tests were conducted to investigate if any beneficial effects exist with an intermittent field. One advantage that was found with a minus 325-mesh feed was an increase in the completeness of the discharge of the magnetic fraction with an intermittent field as illustrated in tables 1-2. Both tests had the same average current of 10.5 amperes through the magnetizing coils of each magnet core illustrated in figure 7. The matrix consisted of 1/16-inch-diameter steel spheres.

In the two short-period comparative tests, the wash water for removing the magnetic fraction was the same and was of a quantity that permitted complete discharge with the intermittent field and partial removal with the constant field. After the test was completed, magnetic particles retained with the constant field were determined by a large increase in the intensity of flow of wash water, a flow volume that would not be practical for normal operation. For separation efficiency, the intermittent field had no advantage over the constant field probably because of a lack of vibration response with minus 325-mesh particles at 60 hertz. This will be described later with dry feeds.

Dry magnetic separation at coarse sizes is not a problem because it may be accomplished with a variety of separator types. Difficulty at fine sizes is twofold. First, the feed rate capacity decreases in the separators with moving conveyor surfaces such as the induced roll and cross-belt separators in which the attracted magnetic particles would have to move at nominal feed rates through a thick layer of nonmagnetic particles; second, an agglomeration effect is present that increases with decrease in particle size.

Results of the separation of several mineral combinations in the size range of minus 200 plus 325 mesh are summarized in tables 3-5. Table 3 illustrates the separation of -Fe2O3 from quartz in an ore with one pass through a matrix of 1/8-inch-diameter steel spheres using the alternating current circuit of figure 6.

Application of an intermittent field with a matrix of 75 percent 1/16-inch-diameter steel spheres and 25 percent 1/8-inch-diameter steel spheres is illustrated in table 4 in a one-pass separation of pyrrhotite from quartz using the circuit of figure 7. Unlike table 3, no attempt was made to obtain an intermediate fraction, which would have resulted in raising and lowering the iron compositions of the magnetic and nonmagnetic fractions, respectively, and provided a fraction for repass with increased recovery.

Table 5 gives the results of the application of a partially modulated field using the circuit of figure 8 and the grooved plate matrix of figure 3 in a one-pass separation of ilmenite from quartz. The advantage of the grooved plate over the spheres is that the particles pass through the matrix in a shorter time. The high flow rate obtained using the grooved plate could be increased further, particularly if water is used, by attaching suction chambers under the disk in a manner similar to applications with continuous vacuum filters. Although the grade and recovery of ilmenite are very high, this need not necessarily be attributed to the grooved-plate matrix since the ampere turns are higher than in any of the other tests. Increased ampere turns is a prerequisite for successful application of alternating current separators and intermittent current separators.

When a minus 325-mesh fraction is tested, a separation sometimes occurs, but in most cases the feed passes through without separation. Response at higher frequencies was investigated with a smaller -inch-cross section U-shaped magnet core 1 (fig. 10). Separation was performed with a nonmagnetic nonconducting plane surface 3 moved manually across the magnet pole as illustrated by the direction arrow 4. When separation occurred, the nonmagnetic mineral 5 would move with the plane, and the magnetic mineral would separate from the nonmagnetic mineral by remaining attached to the magnet pole. When no separation occurred, the entire mixture of magnetic and nonmagnetic minerals would either move with the plane or adhere to the magnet pole.

Four magnetising coils of 119 turns each of No. 14 AWG copper wire were used; three were connected in series with a capacitor as in figure 6, and one was connected to a variable-frequency power supply. The current in the resonant circuit is approximately 5 amperes. When the capacitor has a value of 49 microfarads, the resonant frequency is 130 hertz, and no separation occurs. With the capacitor reduced to 10 microfarads to provide a resonant frequency of 300 hertz, a separation occurs. In the case of a minus 325-mesh -Fe2O3-quartz mixture, most of the quartz moves with the plane, and the -Fe2O3 remains attached to the magnet pole. Similar results are obtained with pyrrhotite-quartz. Indications are that the separation may be improved with preliminary treatment of the feed by dry grinding aids.

frequencies, the time per cycle is too short to permit initial magnetization; at very low frequencies, the magnetization is in phase with the field. The frequencies reported here are between these two extremes and probably near, and just above, the low frequency limit. Experimental values on particles in the size range of minus 35 plus 65 mesh were previously published. These data indicate that 0.16 second, the time required to traverse a magnetizing field distance of 0.9 inch at 5.5 inches per second, is adequate time for the magnetization of minerals, but 0.02 second, the time required to traverse approximately 0.1 inch at the same rate, is too short. Time lag has been reported in the literature for magnetic alloys and has been classified, to the exclusion of the eddy current lag, into a lag that is dependent on impurities and a Jordan lag that is independent of temperature.

From evidence derived from the Barkhausen effect, the magnetization does not proceed uniformly and simultaneously throughout a specimen but is initiated in a limited region from which it spreads in a direction parallel to the field direction at a finite velocity. In a changing magnetic field, the number of initiating nuclei is proportional to the cross-sectional area perpendicular to the direction of the field. For a specimen in the form of a cube, the rate of energy W transferred to the cube would therefore be proportional to the aforementioned cross-sectional area so that for a cube of side s,

Application of intermittent current to the cross-belt separator arose from the need for the dry separation of an iron composition material from the copper in a product submitted by personnel of a Bureau of Mines chalcopyrite vacuum decomposition project. Although this product was of a relatively coarse size, the matted mass resulting from the needle shape or fiber form of the copper and the magnetic field coagulation effects of the magnetic particles prevented use of commercial dry separators such as the induced roll separator and constant-field cross-belt separator. The pulsating magnetic field had a separation effect similar to the pulsations in a hydraulic jig; the pulsating magnetic field permits the nonmagnetic fibers to sink back to the vibrating feeder and allows the magnetic particles to rise to the belt. Other applications would include fibrous minerals such as tremolite, actinolite, and chrysolite, and matted and fibrous secondary materials.

Application of alternating and intermittent current to magnetic separation at a relatively high number of ampere turns was made possible by special electronic circuits. Actual power losses are low and include the IR loss, which is the same that occurs in direct-current magnetic separation, and the core loss, which has a magnitude corresponding to the IR loss. Minerals may be dry-separated close to the minus 325-mesh size at 60-hertz frequency and possibly at smaller particle sizes at higher frequency. In the wet separation of minus 325-mesh feeds, intermittent current provides for complete release of the magnetic fraction during the discharge cycle. For matted fibrous and magnetically coagulating feeds, a cross-belt separator with an intermittent magnetizing current provides efficient separations.

eriez magnetic separation

eriez magnetic separation

Eriez Permanent Magnetic Separators require no electric power. With proper care, they can last a lifetime with very little loss of magnetic field strength. Eriez permanent magnets are supplied for a wide range of applications including dry bulk materials, liquids or slurries and even high temperature applications. Select Eriez Permanent Magnetic Separators are available with the Xtreme RE7 Magnetic Circuit - the industry's strongest magnet!

Eriez Permanent Magnetic Separators require no electric power. With proper care, they can last a lifetime with very little loss of magnetic field strength. Eriez permanent magnets are supplied for a wide range of applications including dry bulk materials, liquids or slurries and even high temperature applications.

Electromagnetic Separators use wire coils and direct current to provide a magnetic field which can be used to separate ferrous material from non ferrous products. Electromagnetic separators offer greater flexibility and strength as well as different magnetic fields for specific applications.

magnetic separation | multotec

magnetic separation | multotec

Multotec supplies a complete range of magnetic separation equipment for separating ferromagnetic and paramagnetic particles from dry solids or slurries, or for removing tramp metal. Multotec Dry and Wet Drum Separators, WHIMS, Demagnetising Coils and Overbelt Magnets are used in mineral processing plants across the world. We can engineer customised magnetic separation solutions for your process, helping you improve the efficiency of downstream processing and lower your overall costs of production.

Multotec provides a wide range of magnetic separators including: Permanent magnet Low Intensity Magnetic Separators (LIMS) or Medium Intensity Magnetic Separators (MIMS) and electromagnetic High Intensity Magnetic Separators (HIMS). Multotec provides unmatched global metallurgical expertise through a worldwide network of branches, which support your processing operation with turnkey magnetic separation solutions, from plant audits and field service to strategic spares for your magnetic separation equipment.

Whether you need to recover fast moving tramp metal, recover valuable metals in waste streams or enhance the beneficiation of ferrous metals, Multotec has the magnetic separator you require. Dry drum cobber magnetic separators provide an initial upgrade of feed material as well as a gangue material rejection stage. By improving the material fed to downstream plant processes, our magnetic separation solutions reduce the mechanical requirements of grinding, ultimately lowering overall costs. Our heavy media drum separators are ideally suited for dense media separation plants. Our ferromagnetic wet drum separators can be used in iron ore separation plants in both rougher or cleaner beneficiation applications. We also provide demagnetising solutions that reverse the residual effects that magnetic separation has on the magnetic viscosity of ferrous slurries, to return the mineral stream to an acceptable viscosity for downstream processing. These demagnetising coils generate a magnetic field that alters magnetic orientation at 200 Hz.

The trend towards larger and faster travelling conveyors in the African mining industry has highlighted the vital role of overbelt magnets. Solutions need to be optimised to such factors as belt speed and width, the belt troughing angle, the burden depth, the material density and bulk density, the expected tramp metal specifications, ambient operating temperatures and suspension height to provide maximum plant and cost efficiency. Multotec can supply complete overbelt magnet systems, from equipment supply to a turnkey service by means of its strategic partners, including even the gantry work.

Related News
  1. manufacturer of magnetic separator for manganese processing 2 india
  2. inertial separator dust collector
  3. magnetic separator wikipedia
  4. spiral classifiers for mineral separation
  5. single screw spiral classifier for gold ore separation
  6. tantalite magnetic separator manufacturer
  7. high quality hydro cyclone classifier separation machine for non ferrous minerals
  8. spiral chute separator adalah
  9. magnetic 0png
  10. what is the core meaning of magnetic separation
  11. vibrating screen spray nozzles
  12. kwekwe medium sand maker sell at a loss
  13. used stampe mill for sale
  14. burning factor means in cement kiln
  15. stone quarry coal crusher rotor in vietnam
  16. tangible benefits medium mineral sand washing machine manufacturer in tabriz
  17. crushed granite archived
  18. rectangle vibrating screen manufacturer
  19. cylinder block grinding milling machine
  20. sat gold mining equipment in south africa