Electrostatic separator mineral separation

The heavy mineral sand concentrates are scmbbed to remove any surface coatings, dried, and separated into magnetic and nonmagnetic fractions (see Separation, magnetic). Each of these fractions is further spHt into conducting and nonconducting fractions in an electrostatic separator to yield individual concentrates of ilmenite, leucoxene, monazite, mtile, xenotime, and zircon. Commercially pure zircon sand typically contains 64% zirconium oxide, 34% siUcon oxide, 1.2% hafnium oxide, and 0.8% other oxides including aluminum, iron, titanium, yttrium, lanthanides, uranium, thorium, phosphoms, scandium, and calcium. 

Induced-roU separators have also been used in the concentration and cleaning of heavy minerals found in beach sands. Examples are the mtUe and ilmenite beach sands of Florida and New Jersey. Induced-roU separators are frequently used in combination with high tension or electrostatic separators. 

A variable-speed drive is usually used on the feed and cross-belt drives to exercise control in separator operation, although the speed is not usually changed once the optimum operating condition is estabUshed. Feed rates and the selection of the number of magnetic poles are usually deterrnined by preliminary laboratory tests. The mineral types involved in the feed largely determine the number of poles selected. High intensity cross-belt separators are frequendy used in combination with induced-roU or electrostatic separators. 

FIG. 19-57 TriiKK lectric separators, -S tat electrostatic separator for silica removal from industrial minerals, (Courtesy of Carpeo., Inc.)... 

TABLE 19-25 Machine Capacities of Electrostatic Separators for Mineral Applications... 

The electrostatic separation method is the exclusive choice in some specific situations, for example in the cases of rutile and ilmenite deposits. These deposits generally contain minerals of similar specific gravities and similar surface properties so that processes such as flotation are unsuitable for concentration. The major application of electrostatic separation is in the processing of beach sands and alluvial deposits containing titanium minerals. Almost all the beach sand plants in the world use electrostatic separation to separate rutile and ilmenite from zircon and monazite. In this context the flowsheet given later (see Figure 2.35 A) may be referred to. Electrostatic separation is also used with regard to a number of other minerals. Some reported commercial separations include those of cassiterite from scheelite, wolframite from quartz, cassiterite from columbite, feldspar from quartz and mica, and diamond from heavy associated minerals. Electrostatic separation is also used in industrial waste recovery. 

Monazite is also found in heavy mineral sands, which are usually recovered using physical concentration methods, such as gravity, magnetic and electrostatic separation. 

A large portion of titanium minerals (ilmenite, rutile) are produced from heavy mineral sands using physical preconcentration methods including gravity, magnetic and electrostatic separation. Over the past 30 years, advances have been made using flotation, where ilmenite, mtile and perovskite can be effectively recovered from both heavy mineral sands and hard rock ores using flotation methods. 

The ilmenite production from heavy mineral sands exclusively utilizes a physical separation method using magnetic separation, gravity concentration and electrostatic separation. Flotation is practiced mainly for beneficiation of fine mineral sands containing rutile, ilmenite and zircon. The ilmenite that is produced in a number of operations in Western Australia, India and the USA is high in chromium, which makes the ilmenite unusable. This section discusses a new process that was developed for chromium removal from ilmenite concentrates. 

Rotor bodies, in steam turbines, 23 231 Rotor electrostatic separators, 16 643-644 Rotor rotating converter, 16 151 Rotors, molecular, 17 59-61 Rotor spinning cotton yarn, 3 17 Rotor-stator devices, 10 127 Rotor-stator disperser, 3 701 Rotor-stator mills, 13 65 Rotor-stator mixers, 16 674-675 Rotosil process, 22 412 Roughages, as ruminant feeds, 10 863 Roughing, in mineral separation, 16 604 Roughing services, magnetic drums used in, 15 446... 

The recovery of valuable minerals and metals requires several stages of sequential processing operations. The mined ore must be crushed and ground to fine sizes prior to treatment by such bene-ficiation processes as heavy-medium separation, tabling, magnetic separation, electrostatic separation, flotation, selective flocculation, etc. Since most of these processes are carried out in aqueous media, solid-liquid separations by such operations as thickening and filtration are an integral part of the benefici-... 

Lawver, J. E., General Principals and Types of Electrostatic Separators, in SME Mineral Processing Handbook, Society of Mining Engineers, 1985. 

FIG. 19-59 Conductive-induction plate-type electrostatic separator. Courtesy of Mineral Technology, Ltd.)... 

Mineral Beneficiation Electrostatic methods are widely used in the processing of ores with mineral concentrates. Generally, electrostatic separation is used as a part of an overall flow sheet comprising various combinations of physical separation procedures. It is particularly well established in the processing of heavy-mineral beach sands from which are recovered ilmenite, rutile, zircon, monazite, silicates, and quartz. High-grade specular hematite concentrates have been recovered at rates of 1000 tons/h in Labrador. Applications also include processing tin ores to separate cassiterite from columbite and ilmenite. Refer to Fig. 19-61 . 

Fig. 2.1 The processing of heavy mineral sands, a) Dredger b) Sieve c) Bunker d) Reichert cones e) Spirals f) Magnetic separator g) Dryer h) Electrostatic separator i) Shaking table j) Dry magnetic separator k) Vertical belt conveyer I) Electrostatic separator.

For concentration (separation of gangue minerals) several methods can be applied, depending mainly on the composition of the ore. They include ore sorting, gravity methods, flotation, magnetic, and electrostatic separation. 

Kelly, D.G. and Spottiswood, D.J. 1989. The Theory of Electrostatic Separations A Review, Part I. Fundamentals, Part II. Particle Charging, Part III. The Separation of Particles. Minerals Engineering, Vol. 2. 

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