| Magnetic separation is an effective method for the separation of magnetic minerals, and has significant technical advantages such as rapid processing, envrionmetnal friendliness, low operation cost and easy operation. Therefore, the development of new magnetic separation technologies and its separators, to overcome the disadvantages of current magnetic separation technologies, has great research significance and application worth. In this investigation, a new wet permanent magnetic separator, entitled wet belt permanent high gradient magnetic separator (WBHGMS), was developed based on the research and design of a new type of magnetic system. A relevant theoretical analysis of WBHGMS was discussed, and the experimental research on separation of various metallic and non-metallic ores using WBHGMS was carried out, the effectiveness of this magnetic separation technology and the practicability of its industrial application was discussed.The main units of WBHGMS included magnetic system, sharply-shaped magnetic poles, frame, feeding chute, rinsing unit, a shallow U shaped belt, unloading unit and frequency conversion speeder. When the separator is operated, the slurry enters through the feed box onto the belt, and flows downwards in a uniform flowing film. Magnetic particles in the film are captured onto the belt and carried upwards by the bulged strips, to where they are rinsed to release entrained non-magnetic particles from magnetic deposits, and then are washed down with water sprays to obtain a magnetic product at the corner of belt. Non-magnetic particles flow downwards with the flowing slurry to become a non-magnetic product.To abtain high magnetic induction and magnetic field gradient on the surface of the magnetic pole, thus abtain high magnetic force, a plate-type magnet is made of NdFeB blocks with high magnetic energy and sharply-shaped magnetic poles. The sharply-shaped magnetic pole, similar to a magnetic matrix, was designed to produce high magnetic induction and magnetic field gradient, so the separator is named as high gradient magnetic separator. This HGMS separator has significant advantages such as compact magnetic circuit and low magnetic leakage, thin belt and strong magnetic induction on belt surface, simple structure, low manufactur cost, high treatment capacity, low energy consumption and easy operation. The experiment resuls show that the separator is applicable for removing iron impurities from non-metallic ores and separation of some weakly magnetic minerals.The distribution characteristics of magnetic field on the belt surface shows that the magnetic field was distributed regularly on the whole working area of belt suface, while the magnetic induction decreased obviously at the edge the magnetic syatem. Perpendicular to the belt movement, the polarities of magnetic field cuve arranged alternately, and the maximum magnetic induction on magnetic pole surface reaches as high as 1.1 T, with an average vatue reasing 1.0 T. From the theoretical discussion on the principle of WBHGMS, it is clear that in a WBHGMS separator, the magnetic field force required for capture of a magnetic particle is related to the properties of magnetic particles such as permeability and density, the characteristics of belt such as surface friction coefficient, and the operating parameters such as flow velocity and rotation speed as well as inclination angle. While the magnetic permeability of particles and the surface friction coefficient of belt are greater, and the inclination angle of the belt and density of minerals is smaller, the magnetic field force required for capture of a magnetic particle is smaller.A pilot-scale WBHGMS separator was used to separate manetic minerals, and the rusults of investigation indicate that:â‘ While the grinding fineness was optimized at 36% below 60 mesh, it produced a non-magnetic product assaying 1.52% Fe at a mass weight of non-magnetic product of 35.76% and an iron removal rate of 95.27% from a Guangdong garnet ore assaying 11.49% Fe; such a performance correlates well with the industrial operation of full-scale separators.â‘¡ While the grinding fineness was optimized at 84% below 60 mesh, it produced a non-magnetic product assaying 0.13% Fe2O3 at a mass weight of non-magnetic product of 91.44% and an iron removal rate of 41.09%(at a magntic iron removal rate of 74.71%) from a Sichuan quartz ore assaying 0.20% Fe2O3;â‘¢ While the grinding fineness was optimized at 82% below 60 mesh, it produced a non-magnetic product assaying 0.23% Fe2O3 at a mass weight of non-magnetic product of 95.58% and an iron removal rate of 36.67%(at a magntic iron removal rate of 74.71%) from a Fujian quartz ore assaying 0.34% Fe2O3;â‘£ While the rotation speed, inclination angle and rinsing water consumption are respectively optimized, it produced a TiO2 concentrate assaying 0.23% TiO2 at recovery of 36.67% from a Sichuan ilmentite ore assaying 0.23% TiO2. It was concluded that this HGMS separator is effective for the purification of non-metallic ores (such as garnet, quartz sand and feldspar as above discussed) and for the separation of metallic ores (such as the ilmentite ore above discussed). And the futher experiment also comfirmed that this HGMS separator is mainly suitable for the separation or removal of magnetic minerals from coarse minerals.In summary, the wet belt permanent high gradient magnetic separator has good technical performance, and it is effective for the purification of non-metallic ores and for the separation of metallic ores. And it has an important industrial application prospect. And provides a new idea for the purification of non-metallic ore and the separation of weakly magnetic minerals.
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