Eriez Rare Earth Roll Separators provide an alternative in handling a wide variety of materials which do not respond well to traditional methods of processing on low intensity dry drum separators or high intensity induced magnetic roll separators.
The extremely powerful high gradient magnetic circuits in the RE Roll are at least ten times the attractive force of conventional ceramic magnets. These separators are capable of recovering particles with a wide range of magnetic susceptibility, and will handle feeds from onehalf inch (13 mm) down to very fine material. Optional lower intensity magnetic materials are also available as a lower cost alternative for specific applications.
PRINCIPLE OF OPERATIONThe continued improvement of high energy rare earth permanent magnetic materials has contributed to an unprecedented acceptance by several industries of rare earth permanent magnetic separators. The evolution of these high strength permanent magnets has led to the development of high intensity separators that operate energy-free. The Rare Earth Roll separator was designed to provide peak separation efficiency and is typically used when a high level of product purity is required. The roll's permanent magnetic discs alternating with thin steel pole pieces along a shaft. The steel poles are saturated with magnetic flux and produce a magnetic field in excess of 21,000 gauss.
The Rare Earth Roll is used as a head pulley, and a thin belt connects the roll to a Dynaloc, self cleaning tail pulley. The standard belting is Teflon coated, graphite filled KEVLAR with thickness of 5 and 10 mils. Accepted belting is also available for food and pharmaceutical applications. The belt conveys the feed material to the magnetic field or separation zone. When the feed enters the magnetic field, the magnetic and/or paramagnetic particles are attracted to the roll while the nonmagnetic material follows the natural discharge trajectory. A splitter arrangement is used to segregate the two streams. Other components of the Rare Earth Roll separator include a vibratory feeder with a mounted hopper, stainless steel product discharges, TEFC gearmotor and controls. The rare earth roll separators are avail- able in single, double and triple stage versions with either nonmagnetic or magnetic rerun.
APPLICATIONSThe Rare Earth Roll separator has been accepted by a number of industries as the most effective magnetic separation method for the purification of nonmagnetic materials. These industries and their specific applications are listed below.
Industrial MineralsEffectively reduces the level of iron from beach sands, feldspar, silica sand, calcium carbon- ate, magnesite, kyanite, bauxite, andalusite, etc. by removing iron bearing minerals such as hematite. Magnetically concentrates weakly magnetic minerals, such as garnet, ilmenite, musovite, mica, etc.
AbrasivesExtremely high levels of product purity are obtained by removing the very fine iron of abrasion and iron smeared on the abrasives. Specific abrasive material treated includes aluminum oxide, silicon carbide, glass beads, tumbling media.
PlasticsIron and/or stainless steel encapsulated in pel- lets are effectively removed from the product stream. Free stainless steel and very fine iron is also removed with very high levels of efficiency.
RecyclingThe RE roll is capable of sorting the nickel and cobalt bearing metal turnings from titanium or zirconium metals. Other applications include removal of shredded aluminum from PET, separation of chrome from crushed automobile grills, and sorting of paramagnetic, synthetic diamonds from natural diamonds.
5-inch Single Rare Earth Magnetic Roll Single non-magnetic tail pulley, belt, adjustable splitter and frame. 1/3 HP RPM motor 230 volt, 3 phase, 60 Hz with variable speed control. 1-1/4 cu. ft. mild steel hopper and mild steel frame mounted on separator frame. Eriez Model 26C Vibratory Feeder, 115V/60Hz with 4" x 20" stainless steel tray. Unicon Feeder Control included.
Single Rare Earth Magnetic Roll. 5 inch magnet width. Single non-magnetic tail pulley, belt, adjustable splitter and frame. 1/3 HP RPM motor 230 volt, 3 phase, 60 Hz with variable speed control. 1-1/4 cu. ft. mild steel hopper and mild steel frame mounted on separator frame. Eriez Model 26C Vibratory Feeder, 115V/60Hz with 4" x 20" stainless steel tray. Unicon Feeder Control included.
Eriez offers a wide variety of processing, mining and flotation laboratory equipment for sale and for sample trials. This equipment is offered around the world. To shop, simply find the equipment you're interested in, review specs and pricing and then provide a ship to and we'll get a final quote and delivery.
Lab equipment includes Jaw crushers, Hammer mills, Pulverizers, Rolls crushers, Ball/Rod mills, Lump breakers/Finger crushers, Test Sieves and Sieve shakers, Drum/Tumble mixers, Cone/V-blenders, Filter presses, SG/ Pulp density scales, Davis tube testers, magnetic separators, flotation equipment and vibratory feeders.
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.
Contact us to find out how Magnetense can help you solve system and productivity challenges. We offer complimentary video, telephone and chat conversations to help you clarify your needs so we can offer cost-efficient solutions.
Project ManagerMr. Giuseppe Zuccon 1. Our drum jacket was wearing too quickly and we also wanted a magnetic separated that would remove small ferrous parts during the production process.. 2. What product did you purchase? Ferrite magnetic drum. 3. What result did you get? We achieved the . removal distance related the test is 170mm which is good. We also noticed the quality of drum is excellent.. 4. Would you recommend us? Yes, we would recommend you.
Manager Head of Technical DepartmentMr. Valter Garbi 1. We had no specific problems; we just needed to reduce our maintenance and supply costs. 2. What product did you purchase? Magnetic rod for our chargers. 3. What result did you get? We conducted a comparative test on our previous and new magnetic separators and found the Magnatense product has far greater magnetic separation efficiency. 4. Would you recommend us? Yes, we would recommend you.
Purchase ManagerIng. Luca Ceccarelli 1. What product did you purchase? Neodymium rods. 2. What result did you get? We found the magnetic performance in our machine significantly improved once we installed your rods. We were able to develop 13,500 Gauss in contact with the pipe and 14,250 on the outside. 3. Would you recommend us? Yes, we would recommend you because your solution offers outstanding magnetic performance compared to other available systems.
Technical ManagerMr. Luca Durante 1. What product did you purchase? We purchased magnetic plates with the neodymium magnet which we installed on a batch feeder for our hammer mill. 2. What was the problem? We needed to remove metal parts that could go into the mill. 3. What result did you get? We successfully removed all unwanted metallic parts. 4. Would you recommend us? Yes, we would recommend you as suppliers of magnetic systems.
Engineering DepartureMr. Vito Lomorno 1. What was the problem? We were using a system where we couldn't separate the iron from unwanted parts. 2. What product did you purchase? Magnetic pulleys and neodymium rings. 3. What result did you get? We achieved a substantial increment in magnetic separation and an improved customer satisfaction rate from our own customers. 4. Would you recommend us? Yes, we would recommend you for your technical expertise and customer service.
Technical ManagerMr. Giovanni Bianchi 1. What was the problem? We could not prevent ferrous parts from accidentally entering the hammer mill. 2. What product did you purchase? Ferritic magnetic plate. 3. What result did you get? The magnetic plate we purchased has prevented all ferrous objects from entering the upper part of the mill. 4. Would you recommend us? Yes, without any doubt we would recommend you and your product.
Chief ExecutiveSig. Giordano Luca 1. What was the problem? Intercepting iron particles flowing in a pipe used to pneumatically load flour from cisterns to silos. 2. What product did you purchase? Pressurised magnetic piping. 3. What result did you get? The pneumatically loaded flour is free from ferrous particles and it is now safe to move to the next process steps. The machinery is protected from ferrous contaminants. 4. Would you recommend us? Yes, we would definitely recommend you.
Purchase ManagerSig. Paolo Massano 1. What was the problem? Our existing magnetic system did not remove iron from the mill feeders at a satisfactory rate. 2. What product did you purchase? We purchased the Neodymium or ferrite sticks with a 32mm diameter and a 200mm length. 3. What result did you get? We achieved a significant improvement in the removal rate when compared with the previous system. 4. Would you recommend us? Yes, I would recommend you.
Purchase ManagerSig.ra Stefania Manelli 1. What was the problem?Compartment in enamel filters. 2. What product did you purchase?We purchased a magnetic bar with a 32 diameter and 70 mm length. 3. What result did you get?We obtained good results.. 4. Would you recommend us?Yes, I would recommend you.
Established in Italy in 2000 to meet the growing demand for reliable and robust magnetic systems, Magnetense today is a world leader in the efficient design, build and distribution of state-of-the-art magnets, magnetic systems and consultancy services.
Products provided by Magnetence include ferrite/neodymium magnets; manufacturing; and production of magnetic separators such as drums, rolls, plates, overbands, pipings, filters, rods, bars and textile rods.
The WHIMS separator is a magnetic separation machine used in wet separation processes to treat fine grain materials which are smaller than 1.2mm or 200 mesh. These fine grain materials include red mine hematite, limonite, manganese ore, and ilmenite. The WHIMS is also used to treat magnetic minerals including quartz, feldspar, nepheline ore, and kaolin. This system removes iron contaminants to concentrate the treated minerals.
The Balance 2 Drum Magnet features a maximum 10,000 Gauss magnetic power: among the most powerful available on the marketThis drum achieves an excellent wear resistance which is due to Magnetenses unique BL2 balancing system. The BL2 is designed to be easily assembled and tested.
The RO and FLY magnetic rods are newly reinvented rods that have been specifically designed and built by the team at Magnetense. The RO models have a magnetic power of between 6,500 and 12,000 Gauss and the FLY model achieves a maximum power of 14,000 Gauss. The RO and FLY rods are made from high grade neodymium with single section mechanical structures and no moving parts. All rods have exceptional wear resistance which is more than double industry standard and which contributes to long-lasting efficiency.
The Overband Shark and Ova magnetic belts have been uniquely designed to include a combination of ferrite and neodymium magnets. Older generation conveyor belts were generally only fitted with ferrite magnets. This new belt design enables producers to reach more than 5507 Gauss along with a 10 per cent lighter structure when compared to other industry-standard overbelts.
The HMF electromagnetic filters are used in wet process separation of para-magnetic minerals found in quartz, feldspar,silicates, calcium carbonate and kaolin. The flow-rates are engineered in accordance with customer requirements.
The MAG Dry Magnetic Separators include the 1.10/15 and the MAG 3.10/15. Both machines have been designed and manufactured to de-iron a range of sand materials. This includes paramagnetic minerals such as hematite, biotite, ilmenite which are easily captured by Tiger Pulleys powerful magnets. The MAG 1.10/15 and the MAG 3.10/15 magnetic separators are specifically calibrated to remove fine iron particle sizes ranging from 0.1 to 1.8 mm.
The Gravity Feed, Pneumatic Pipe and Electric Pipe magnets comprise a specialist mechanical structure that guarantees higher than industry standard wear resistance. The structure is made from high grade neodymium which allows users to achieve 20% per cent more power than our older generation pipe magnets.
The Tiger Magnetic Pulleys have a diameter of 300mm and a working height of 1500 mm which gives these pulleys a much higher capacity than lower height and diameter machines. These features are combined with an exceptional magnetic power of 12,310+ Gauss that is in contact with the surface and which allows the magnetic rollers to practically catch any magnetic particle or paramagnetic mineral.
The ROL Magnetic Pulley is manufactured with double cross poles which helps the system to reach much higher magnetic power than standard industry separators. The ROL is fixed with Magnetenses Track fixing system which guarantees close to unlimited efficiency and resistance.
The PLV1 Magnetic Plates add an entire new dimension to plate design and use. The aesthetically pleasing PLV1 has exceptional wear resistance and separation efficiency of between 15 and 20 per cent more than our older generation systems. The PLV1 is also equipped with magnetic shielding to help mitigate workplace accidents.
The PLV2 Magnetic Plates add an entire new dimension to plate design and use. The aesthetically pleasing PLV2 has exceptional wear resistance and separation efficiency of between 15 and 20 per cent more than our older generation systems. The PLV2 is also equipped with magnetic shielding to help mitigate workplace accidents.
Our new Batex Magnetic Textile Bars achieve 25 per cent more magnetic field power than our older separation systems. This result was achieved following constant tests aimed at improving the performance of the magnetic system. The New Batex bar also achieves a better separation of iron, even with the same magnetic field.
Established in Italy in 2000 to meet the growing demand for reliable and robust magnetic systems, Magnetense today is a world leader in the efficient design, build and distribution of state-of-the-art magnets, magnetic systems and consultancy services.
Products provided by Magnetence include ferrite/neodymium magnets; manufacturing; and production of magnetic separators such as drums, rolls, plates, overbands, pipings, filters, rods, bars and textile rods.
Magnetense team of engineers are responsible for the entire process including research, design, manufacturinge and global distribution of all products and services. By controlling the entire process operating costs are reduced to the minimum so products are sold to end users competitive price.
Unfortunately there are many magnetic systems manufacturers that promise unreal results eventually not achievable: by conducting a magnetic field measurement created by their systems their claims can be debunked.
In some cases magnetic system manufacturers chose to demonstrate their magnetic performances based on calculations in a closed circuit or through the incorrect use of an instrument; by testing their system any false claim can be debunked.
Magnetic performances based on calculations in a closed circuit or through the incorrect use of an instrument Are often claimed by magnetic system manufactured, but, physics is not made of fairy tales their claims can be easily exposed.
Contact us to find out how Magnetense can help you overcoming system and productivity challenges. We offer complimentary video, telephone and chat conversations to help you clarifying your needs in order to present you with the most cost-efficient solutions.
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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.
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.
The Jones wet high-intensity magnetic separator (WHIMS) was developed in 1956. The structure of the Jones separator is shown in Figure 9.6 and consists mainly of an iron-core electromagnet, a vertical shaft with two (or more) separating rings, a driving system, and feeding and product collection devices. Grooved plates made of magnetic conductive iron or stainless steel serve as a magnetic matrix to enhance the field gradient of the electromagnet. The plates are vertically arranged in plate boxes that are placed around the periphery of the rotors. When the Jones magnetic separator is operating, its vertical shaft drives the separating rings with the matrix plates rotating on a horizontal plane.
When a direct electric current passes through the energizing coils, a high magnetic field with a high gradient is established in the separating zone located in the electromagnetic system, with the focused magnetic field at the teeth top of the grooved plates reaching 0.82T, which is adjustable. The slurry is gravity fed onto the matrix at the leading edge of the magnetic field where the magnetic particles are captured on the teeth top of the grooved plates, while the nonmagnetic fraction passes through and is collected in a trough below the magnet. When the plate boxes reach the demagnetized zone half-way between the two magnetic poles, where the magnetic field changes its polarity, the magnetic field is essentially zero and the adhering magnetic particles are washed out with high-pressure water sprays.
In the past, cross-belt and rotating disc high-intensity magnetic separators were used for concentration of relatively coarse weakly magnetic particles such as wolframite and ilmenite, etc., under dry conditions. In the operation of these two magnetic separators, material is distributed onto the moving conveyor belt in a very thin layer, through a vibrating feeder. Such magnetic separators are not effective even inapplicable for the treatment of fine materials.
With the increasing reduction in liberation size of valuable components in magnetic ores, the conventional cross-belt and rotating disc high-intensity magnetic separators are almost replaced by gravity and flotation, particularly by high-gradient magnetic separators, as a result of its effectiveness to fine materials and high solids throughput. In the recent years, however, a wet permanent disc high-intensity magnetic separator as shown in left Figure7 seems applicable in recovering fine magnetic particles from tailings. In this disc separator, slurry is fed across a round tank, in which vertically rotating discs with permanent magnet blocks pick up fine magnetic particles, and they are brought up and scraped down by rotating scrapers, near the top of discs. Nonmagnetic particles are discharged at the bottom of tank.
And, a dry high-intensity roll magnetic separator as shown in right Figure7 is replacing the conventional roll magnetic separators and is used for concentration of relatively coarse magnetic particles. The design of such a roll magnetic separator is similar to that of the conventional roll magnetic separator, but it achieves a higher magnetic induction and its installation requires a much smaller occupation for space.
Ferromagnetic solids of high magnetic permeability can be separated in a Low Intensity Magnetic Separator (LIMS) using permanent magnets of less than 2 T (see Figure 1.56). A typical unit operates continuously and comprises a rotating non-magnetic drum inside which four to six stationary magnets are placed. The wet or dry feed contacts the outer periphery of the drum and the magnetically susceptible particles are picked up and discharged leaving the weakly or non-magnetic material to pass by largely unaffected. Alternative designs include the disc separator and the cross-belt separator where dry solids are conveyed towards a cross-belt which moves across a series of permanent magnets.
The efficiency of magnetic separation is generally improved by maximising both the intensity and the gradient of an applied non-uniform field. By doing so paramagnetic material of low magnetic permeability can be separated in a High Intensity Magnetic Separator (HIMS). Electromagnets, with intensities in excess of 2 T, are used in continuous equipment such as the Jones rotating disc separator to affect separations of dry feeds down to 75 m and wet feeds to finer sizes. Very weakly paramagnetic material cannot usually be separated satisfactorily with a HIMS, and a High Gradient Magnetic Separator (HGMS) must be used (Figure 1.56). In these units a matrix of fine stainless steel wool is placed between the poles of either electromagnetic or superconducting magnets, the latter generating magnetic intensities up to 15 T. Very high magnetic gradients are produced adjacent to the wool fibres and this allows for the separation of very fine particulates. Although the capital cost of HGMS can be relatively high compared with more conventional equipment, commercial units are readily available.
Iron ore processors may also employ magnetic separation for beneficiation of classifier output streams. Wet high-intensity magnetic separators (WHIMS) may be used to extract high-grade fine particles from gangue, due to the greater attraction of the former to the applied magnetic field.
In addition to beneficiating the intermediate middlings streams from the classifier, WHIMS may be used as scavenger units for classifier overflow. This enables particles of sufficient grade to be recovered that would otherwise be sacrificed to tails.
Testwork has been performed on iron ore samples from various locations to validate the use of magnetic separation following classification (Horn and Wellsted, 2011). A key example was material sourced from the Orissa state in northeastern India, with a summary of results shown in Table 10.2. The allmineral allflux and gaustec units were used to provided classification and magnetic separation, respectively.
The starting grade of the sample was a low 42% Fe. It also contained significant ultrafines with 58% passing 20m. This is reflected in the low yield of allflux coarse concentrate; however, a notable 16% (abs) increase in iron grade was eventually achieved. The gaustec results for the middlings and overflow streams demonstrate the ability to recover additional high-grade material. With the three concentrate streams combined, an impressive yield of almost 64% was achieved with minimal decline in iron grade.
Various classification schemes exist by which magnetic separators can be subdivided into categories. Review of these schemes can be found in monographs by Svoboda (1987, 2004). The most illustrative classification is according to the magnitude of the magnetic field and its gradient.
Low-intensity magnetic separators (LIMS). They are used primarily for manipulation of ferromagnetic materials or paramagnetic of high magnetic susceptibility and/or of large particle size. These separators can operate either in dry or wet modes. Suspended magnets, magnetic pulleys, and magnetic drums are examples of these separators. Operation of a dry drum separator is shown in Fig. 3.
High-intensity magnetic separators. They are used for treatment of weakly magnetic materials, coarse or fine, in wet or dry modes. Induced magnetic rolls (IMR), permanent magnet rolls and drums, magnetic filters, open-gradient (OGMS) and wet high-intensity magnetic separators (WHIMS) are examples of this class of separators.
Weakly paramagnetic minerals can only be effectively recovered using high-intensity (B-fields of 2T or greater) magnetic separators (Svoboda, 1994). Until the 1960s, high-intensity separation was confined solely to dry ore, having been used commercially since about 1908. This is no longer the case, as many new technologies have been developed to treat slurried feeds.
Induced roll magnetic (IRM) separators (Figure 13.19) are widely used to treat beach sands, wolframite and tin ores, glass sands, and phosphate rock. They have also been used to treat weakly magnetic iron ores, principally in Europe. The roll, onto which the ore is fed, is composed of phosphated steel laminates compressed together on a nonmagnetic stainless steel shaft. By using two sizes of laminations, differing slightly in outer diameter, the roll is given a serrated profile, which promotes the high field intensity and gradient required. Field strengths of up to 2.2T are attainable in the gap between feed pole and roll. Nonmagnetic particles are thrown off the roll into the tailings compartment, whereas magnetics are held, carried out of the influence of the field and deposited into the magnetics compartment. The gap between the feed pole and rotor is adjustable and is usually decreased from pole to pole (to create a higher effective magnetic field strength) to take off successively more weakly magnetic products.
The primary variables affecting separation using an IRM separator are the magnetic susceptibility of the mineral particles, the applied magnetic field intensity, the size of the particles, and the speed of the roll (Singh et al., 2013). The setting of the splitter plates cutting into the trajectory of the discharged material is also of importance.
In most cases, IRM separators have been replaced by the more recently developed (circa 1980) rare earth drum and roll separators, which are capable of field intensities of up to 0.7 and 2.1T, respectively (Norrgran and Marin, 1994). The advantages of rare earth roll separators over IRM separators include: lower operating costs due to decreased energy requirements, less weight leading to lower construction and installation costs, higher throughput, fewer required stages, and increased flexibility in roll configuration which allows for improved separation at various size ranges (Dobbins and Sherrell, 2010).
Dry high-intensity separation is largely restricted to ores containing little, if any, material finer than about 75m. The effectiveness of separation on such fine material is severely reduced by the effects of air currents, particleparticle adhesion, and particlerotor adhesion.
Without doubt, the greatest advance in the field of magnetic separation was the development of continuous WHIMSs (Lawver and Hopstock, 1974). These devices have reduced the minimum particle size for efficient magnetic separation compared to dry high-intensity methods. In some flowsheets, expensive drying operations, necessary prior to a dry separation, can be eliminated by using an entirely wet concentration system.
Perhaps the most well-known WHIMS machine is the Jones separator, the design principle of which is utilized in many other types of wet separators found today. The machine has a strong main frame (Figure 13.20(a)) made of structural steel. The magnet yokes are welded to this frame, with the electromagnetic coils enclosed in air-cooled cases. The separation takes place in the plate boxes, which are on the periphery of the one or two rotors attached to the central roller shaft and carried into and out of the magnetic field in a carousel (Figure 13.20(b)). The feed, which is thoroughly mixed slurry, flows through the plate boxes via fitted pipes and launders into the plate boxes (Figure 13.21), which are grooved to concentrate the magnetic field at the tip of the ridges. Feeding is continuous due to the rotation of the plate boxes on the rotors and the feed points are at the leading edges of the magnetic fields (Figure 13.20(b)). Each rotor has two feed points diametrically opposed to one another.
The weakly magnetic particles are held by the plates, whereas the remaining nonmagnetic particle slurry passes through the plate boxes and is collected in a launder. Before leaving the field any entrained nonmagnetics are washed out by low-pressure water and are collected as a middlings product.
When the plate boxes reach a point midway between the two magnetic poles, where the magnetic field is essentially zero, the magnetic particles are washed out using high-pressure scour water sprays operating at up to 5bar. Field intensities of over 2T can be produced in these machines, although the applied magnetic field strength should be carefully selected depending on the application (see Section 13.4.2). The production of a 1.5T field requires electric power consumption in the coils of 16kW per pole.
There are currently two types of WHIMS machines, one that uses electromagnetic coils to generate the required field strength, the other that employs rare earth permanent magnets. They are used in different applications; the weaker magnetic field strength produced by rare earth permanent magnets may be insufficient to concentrate some weakly paramagnetic minerals. The variables to consider before installing a traditional horizontal carousel WHIMS include: the feed characteristics (slurry density, feed rate, particle size, magnetic susceptibility of the target magnetic mineral), the product requirements (volume of solids to be removed, required grade of products), and the cost of power (Eriez, 2008). From these considerations the design and operation of the separator can be tailored by changing the following: the magnetic field intensity and/or configuration, the speed of the carousel, the setting of the middling splitter, the pressure/volume of wash water, and the type of matrix material (Eriez, 2008). The selection of matrix type has a direct impact on the magnetic field gradient present in the separation chamber. As explained in Section 13.4.2, increasing magnetic field can in some applications actually cause decreased performance of the magnetic separation step and it is for this reason that improvements in the separation of paramagnetic materials focus largely on achieving a high magnetic field gradient. The Eriez model SSS-I WHIMS employs the basic principles of WHIMS with improvements in the matrix material (to generate a high field gradient) as well as the slurry feeding and washing steps (to improve separation efficiency) (Eriez and Gzrinm, 2014). While this separator is referred to as a WHIMS, it is in fact more similar to the SLon VPHGMS mentioned in Sections 13.4.1 and 13.5.3. Further discussion on high-gradient magnetic separation (HGMS) may be found in Section 13.5.3.
Wet high-intensity magnetic separation has its greatest use in the concentration of low-grade iron ores containing hematite, where they are an alternative to flotation or gravity methods. The decision to select magnetic separation for the concentration of hematite from iron ore must balance the relative ease with which hematite may be concentrated in such a separator against the high capital cost of such separators. It has been shown by White (1978) that the capital cost of flotation equipment for concentrating weakly magnetic ore is about 20% that of a Jones separator installation, although flotation operating costs are about three times higher (and may be even higher if water treatment is required). Total cost depends on terms for capital depreciation; over 10 years or longer the high-intensity magnetic separator may be more attractive than flotation.
In addition to recovery of hematite (and other iron oxides such as goethite), wet high-intensity separators are now in operation for a wide range of duties, including removal of magnetic impurities from cassiterite concentrates, removal of fine magnetic material from asbestos, removal of iron oxides and ferrosilicate minerals from industrial minerals such as quartz and clay, concentration of ilmenite, wolframite, and chromite, removal of magnetic impurities from scheelite concentrates, purification of talc, the recovery of non-sulfide molybdenum-bearing minerals from flotation tailings, and the removal of Fe-oxides and FeTi-oxides from zircon and rutile in heavy mineral beach sands (Corrans and Svoboda, 1985; Eriez, 2008). In the PGM-bearing Merensky Reef (South Africa), WHIMS has been used to remove much of the strongly paramagnetic orthopyroxene gangue from the PGM-containing chromite (Corrans and Svoboda, 1985). WHIMS has also been successfully used for the recovery of gold and uranium from cyanidation residues in South Africa (Corrans, 1984). Magnetic separation can be used to recover some of the free gold, and much of the silicate-locked gold, due to the presence of iron impurities and coatings. In the case of uranium leaching, small amounts of iron (from milling) may act as reducing agents and negatively affect the oxidation of U4+ to U6+; treatment via WHIMS can reduce the consumption of oxidizing agents by removing a large portion of this iron prior to leaching (Corrans and Svoboda, 1985).
At the CliffsWabush iron ore mine in Labrador, Canada (Figure 13.22), the cyclone overflow from the tailings of a rougher spiral bank is sent to a magnetic scavenger circuit utilizing both low-intensity drum separation and WHIMS. This circuit employs the low-intensity (0.07T) drum separators to remove fine magnetite particles lost during the spiral gravity concentration step, followed by a WHIMS step using 100th1 Jones separators which are operated at field strengths of 1T to concentrate fine hematite. Cleaning of only the gravity tailings by magnetic separation is preferred, as relatively small amounts of magnetic concentrate have to be handled, the bulk of the material being essentially unaffected by the magnetic field. The concentrate produced from this magnetic scavenging step is eventually recombined with the spiral concentrate before feeding to the pelletizing plant (Damjanovi and Goode, 2000).
The paramagnetic properties of some sulfide minerals, such as chalcopyrite and marmatite (high Fe form of sphalerite), have been exploited by applying wet high-intensity magnetic separation to augment differential flotation processes (Tawil and Morales, 1985). Testwork showed that a Chilean copper concentrate could be upgraded from 23.8% to 30.2% Cu, at 87% recovery.
By creating an environment comprising a magnetic force (Fm), a gravitational force (Fg), and a drag force (Fd), magnetic particles can be separated from nonmagnetic particles by MS. Magnetic separators exploit the differences in magnetic properties between particles. All materials are affected in some way when placed in a magnetic field.
where V: particle volume (determined by process); X: magnetic susceptibility; H: magnetic field (created by the magnet system design) in mT; GradH: magnetic field gradient (created by the magnet system design) in mT (mT: milli Tesla, 1kGauss=100mT=0.1T). Materials are classified into two broad groups according to whether they are attracted to or repelled by a magnet. Non/diamagnetics are repelled from and ferro/paramagnetics are attracted to magnets. Ferromagnetic substances are strongly magnetic and have a large and positive magnetism. Paramagnetic substances are weakly magnetic and have a small and positive magnetism. In diamagnetic materials, the magnetic field is opposite to the applied field. Magnetisms are small and negative. Nonmagnetic material has zero magnetism. Ferromagnetism is the basic mechanism by which certain materials (such as Fe) form permanent magnets, or are attracted to magnets. Ferromagnetic materials can be separated by low-intensity magnetic separators (LIMSs) at less than 2T magnetic intensity. Paramagnetic materials can be separated by dry or wet high-intensity magnetic separators (HIMSs) at 1020T magnetic intensities. Diamagnetic materials create an induced magnetic field in the direction opposite to an externally applied magnetic field, and are repelled by the applied magnetic field. Nonmagnetic substances have little reaction to magnetic fields and show net zero magnetic moment due to random alignment of the magnetic field of individual atoms. Induced roll separators, with field intensities up to 2.2T, and Permroll separators can be used for coarse and dry materials (>75m). Fine materials reduce the separation efficiency due to particlerotor and particleparticle agglomeration. For wet HIMS, Gill and Jones separators are used at a maximum field of 1.4 and 1.5T, at 150m size . Dry LIMSs are used for coarse and strongly magnetic substances. The magnetic field gradient in the separation zone (approximately 50mm from the drum surface) ranges between 0.1 and 0.3T. Below 0.5cm, dry separation tends to be replaced by wet LIMS. Concurrent and countercurrent drum separators have a nonmagnetic drum containing three to six stationary magnets of alternating polarity. Separation depends on the pick up principles. Magnetic particles are lifted by magnets and pinned to the drum and then conveyed out of the field. Field intensities up to 0.7T at the pole surfaces can be used. Coarse particles up to 0.56mm can be tolerated. The drum diameter is 1200mm and the length 6003600mm. Concurrent operation is normally used as a primary separation (cobber) for large capacities and coarse feeds. Countercurrent operation is used as a rougher and finisher for multistage concentration.
Moderately magnetic dry substances on a conveyor/belt can be collected by overhead, cross-belt, or disc separators using magnetic field intensities between 0.8 and 1.5T. Very weakly paramagnetic substances can only be removed if field intensities are greater than 2.0T. At 5200mm size fractions, overhead permanent magnets are used to remove ferromagnetics. Magnetic separators, such as dry low-intensity drum types, are widely used for the recovery of ferromagnetic materials from nonferrous metals (Al and Cu) and other nonmagnetic materials (plastic and glass) at 5mm in size. The magnetic field may be generated by permanent magnets or electromagnets. There have been many advances in the design and operation of HIMS due mainly to the introduction of rare-earth alloy permanent magnets with the capability of providing high field strengths and gradients. There are, however, some problems associated with this method. One of the major issues is agglomeration of the particles, which results in the attraction of some nonferrous fractions attached to the ferrous fractions . This leads to low efficiency of this method. Through the process of MS, it is possible to obtain two fractions: the magnetic fraction, which includes Fe, steel, Ni, etc., and the nonmagnetic fraction, which includes Cu . For WEEE, MS systems utilize ferrite, rear-earth or electromagnets, with high-intensity electromagnet systems being used extensively. Veit et al.  employed a magnetic field of 0.60.65T to separate the ferromagnetic elements, such as Fe and Ni. The chemical concentration of the magnetic fraction was 43% Fe and 15.2% Ni on average. However, there was a considerable amount of Cu impurity in the magnetic fraction as well. Yoo et al.  used a two-stage MS for milled PCBs. The milled PCBs of particle size >5.0mm and the heavy fraction were separated from the <5.0mm PCB particles by gravity separation. In the first stage, a low magnetic field of 0.07T was applied, which led to the separation of 83% of Ni and Fe in the magnetic fraction and 92% of Cu in the nonmagnetic fraction. The second MS stage was conducted at 0.3T, which resulted in a reduction in the grade of the NiFe concentrate and an increase in the Cu concentrate grade.
Magnetic separations depend on a particle's magnetic susceptibility in a magnetic field. Based on magnetic susceptibility, materials can be one of two types: paramagnetic (those attracted by a magnetic field) and diamagnetic (those repelled by a magnetic field). It is usual to consider strongly magnetic materials as being in a separate category called ferromagnetic.
Magnetic separators are divided into low-intensity and high-intensity separators, the former being used for ferromagnetic minerals (and some paramagnetic minerals of high magnetic susceptibility) and the latter used for paramagnetic minerals of (lower) magnetic susceptibility. (In effect, a third category of separator exists: that used for removing tramp iron from process streams.) High- and low-intensity separation can be carried out wet or dry: tramp separators operate only on dry streams.
The most common separator, the wet low-intensity, consists of a revolving drum partly submerged in a suspension. An arc of magnets within the drum pulls the magnetically susceptible material against the drum, lifting it out of the slurry and over a discharge weir. Permanent ceramic magnets are now typical in these units.
Dry high-intensity separators use powerful electromagnets that induce a magnetic field in a comparatively small diametered roll, against which the magnetically susceptible particles are held until they pass a suitable discharge point.
where r=radial distance; V=particle volume; p, m=magnetic susceptibility of particle and medium, respectively. This shows that the force depends on both the strength and the gradient of the magnetic field. The latter component is especially significant in WHIMS, where high curvature ferromagnetic surfaces (e.g., wire, balls) are used to produce very high gradients.
An indication of the lower limits of particle size that can be treated in a magnetic separator can be obtained by balancing the magnetic force against the likely opposing forces (usually fluid drag and gravitation), but with the addition of centrifugal forces in drum separators. Mechanical considerations usually determine the upper particle size limit.
In principle, separability and performance curves can be used to predict separator performance. However, difficulties arise in determining properties independent of experimental conditions, so the approach has not been widely used.
Two simple models of wet low-intensity drum separators have been described. One uses a probability concept while the other empirically correlates losses of magnetic material near the drum take-up and discharge with feed rate and drum speed.
Nanomaterials have also been prepared by ball milling the parent materials. High-energy ball milling not only prepares nanoparticles quickly but it also uses little chemicals as compared to the sol-gel methods. However, it has low energy efficiency because it dissipate a lot of energy in form of heat.
Planetary ball mill was used to synthesize iron nanoparticles. The synthesized nanoparticles were subjected to the characterization studies by X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques using a SIEMENS-D5000 diffractometer and Hitachi S-4800. For the synthesis of iron nanoparticles, commercial iron powder having particles size of 10m was used. The iron powder was subjected to planetary ball milling for various period of time. The optimum time period for the synthesis of nanoparticles was observed to be 10h because after that time period, chances of contamination inclined and the particles size became almost constant so the powder was ball milled for 10h to synthesize nanoparticles . Fig. 12 shows the SEM image of the iron nanoparticles.
The next step involved the crushing of the pyrite particle by high-energy ball milling at a rate of 320rpm for various periods of time, that is, 2, 4, and 6h which ultimately resulted in the formation of pyrite nanoparticles.
The process of ball milling was employed under controlled parameters about 298K temperature and 760 torr pressure. Stainless steel made ball and bowl were utilized for the process. In the process, ball:pyrite ratio of 10:1 was selected and at varying time periods of 2h, the samples were removed. The method was named as interrupted milling. The synthesized nanoparticles were washed with ethyl alcohol thrice to eradicate contamination. The nanoparticles were dried in an oven for 4h at 50C [12,13]. Fig. 13 shows the SEM image of the nanoparticles.
Jaw and cone crushing was performed on the martite ore until they became within the size range of 0.52cm. The sample was further crushed by ball and rod milling until the particles size was reduced to 3050lm. Ultimately, the particles were subjected to interrupt high-energy planetary ball milling for different time durations, that is, 2, 4, and 6h to get the nanoparticles of martite. The ball:martite ratio of 10:1 was selected and a rotation speed of 320rpm was chosen . Fig. 14 shows the SEM images of martite nanoparticles.
Caron onions preparation was carried out by employing graphite carbon having high purity. A reported method was used to synthesize AlCuFe quasicrystal. The synthesis of alloy was carried out under ambient environment. The percentage composition of alloy material was set to be Al64Cu24Fe12. The alloy was solidified under ambient conditions. Annealing of the synthesized alloy was performed under argon environment at 700C for 96h. The synthesized composite material is brittle and inclines to be fractured when subjected to ball milling process. In this typical procedure, the reaction of moisture with aluminum in the composite results in the formation of aluminum oxide film over the surface but simultaneously, the release of atomic hydrogen incites cleavage fracture of the composite material and occasionally it was observed that the whole material got converted into fine powder after a few days. Graphite and the composite materials were mixed in 1:1 ratio and then high-energy ball milling was performed on the mixture under ambient environment. Ball milling was performed for various time periods of 1.5, 3, 6, and 10h. The ball milling media was composed of hard steel vials and balls having a ratio of powder:ball to be 1:7. The mixture was grinded using a grinding medium size of 12.7mm. The synthesized nanocomposites were characterized using various techniques including XRD, Raman spectroscopy, TEM, and the size of the nanoparticles was observed to be within 412nm . Fig. 15 shows the TEM image of the nanoparticles.
A modified ball milling device having assistance of ultrasonication was employed in the synthesis of zinc oxide nanoparticles. The synthesis of nanoparticles involved analytical grade zinc acetate dihydrated salt as the zinc precursor material. Ball milling medium of stainless steel with diameter of balls of 2mm was employed. The ratio of milling balls to the zinc precursor was set to be 1:100. The frequency and power of the microwave were 2450MHz and 0.8kW, respectively. The synthesized nanoparticles were characterized by UV-Visible spectroscopy, XRD, TEM, fluorescence measurements, and electroconductivity detections. The average size of the nanoparticles was observed to be 15nm . Fig. 16 shows the TEM image of the nanoparticles.
The synthesis of Na3MnCO3PO4 nanoparticles involved dry ball milling of the precursors. The precursors of the nanoparticles were Mn(NO3)2.4H2O (A), Na2HPO4.2H2O (B), and Na2CO3.H2O (C). The concentrations optima were evaluated by doing extensive preliminary experiments and the amount of 8mmol of A and B and 12mmol of C. Planetary ball milling of the mixture was performed by keeping a ball: mixture ratio of 30:1. The mixture was ball milled for different time periods, that is, 15, 30, 60, and 180min at a rate of 300rpm. The synthesized billed nanoparticles were then added into deionized distilled water under continuous stirring so that the nanoparticles can be separated from impurities. The nanoparticles were separated and characterized by various techniques . SEM image of the nanoparticles are provided in Fig. 17.
High intensity dry magnetic separators are gaining popularity for the separation of para-magnetic minerals due to the cost economic factor. Induced roll magnetic separator is found to be an effective dry separator for the separation of fine particles. Separation efficiency of this separator depends on mineral characteristics and the design features of equipment along with the optimization of process variables. Present investigation focuses on the prediction and validation of separation performance of minerals while treating in induced roll magnetic separator. Prediction of the separation is expressed in terms of separation angle at which a particle leaves the rotor surface by using a modified particle flow model derived by Cakir. The validation of the model is carried by capturing the particle trajectory using an image analyzer. It is found that Cakirs mathematical model produces reliable results and a new model is proposed to increase the reliability of separation angle prediction by including the particle shape factor.
J.H.P. Watson, D. Rassi, Single-wire magnetic separation: a diagnostic tool for mineral processing. in MINTEK 50-International Conference on Mineral Science and Technology, Sandton, South Africa. The Council for Mineral Technology, Randburg, South Africa, 2630 March, 1984
D. Wang, M. Jiang, C. Liu, Y. Min, Y. Cui, J. Liu, J. Zhang, Enrichment of Fe-containing phases and recovery of iron and its oxides by magnetic separation from BOF slags. Steel Res. Int. 83, 189196 (2012)
I. Cakir, A.J.W. Rozelaar, I.S. Wells, A preliminary analysis of the mechanical forces acting on a particle on the rotor of an electrostatic separator. in Proc. XII Int. Miner. Proc. Congress, Sao Paulo (1977), p. 4
Tripathy, S.K., Singh, V. & Suresh, N. Prediction of Separation Performance of Dry High Intensity Magnetic Separator for Processing of Para-Magnetic Minerals. J. Inst. Eng. India Ser. D 96, 131142 (2015). https://doi.org/10.1007/s40033-015-0064-x
Separate ferromagnetic and paramagnetic particles and tramp metals with the worlds most efficient solutions. Wet High Intensity Magnetic Separators (WHIMS) from Multotec combine magnetism, matrix rotation and gravity to para-magnetic materials. Applications include heavy minerals, ilmenite, manganese and iron ore (haematite) beneficiation; PGM upgrading as well as manganese recovery from slimes dams. This offers innovative new approaches and technology for solving para-magnetic minerals separation processes that are as efficient as they are cost-effective. Magnetic separators that used permanent magnets could generate fields of low intensity only. These worked well in removing ferrous tramp but not fine para-magnetic particles. High intensity magnetic separators focus on the separation of very fine particles that are para-magnetic. The current is passed through the coil, which creates a magnetic field. This magnetises the yoke and finally the matrix ring. The para-magnetic matrix material behaves like a magnet and attracts the fines. The ring is rinsed when it is out of the magnetic field and all the magnetic particles are carried into a magnetised launder within the rinse water. This technology also employs unparalleled high gradients to allow recovery of fine material down to 15 micron. The WHIMS was specially adapted by Multotec to accommodate the demands of the African environment. This has resulted in highly specialised magnetic separation equipment that complements and enhances Multotecs existing solution offering.Get in Touch with Mechanic