Electric separation ( Eng. Electric separation ; German Elektroscheidung f ) - the process of separation of dry particles of minerals or materials in an electric field according to the magnitude or sign of the charge created on the particles depending on their electrical properties, chemical composition, size.
Content
Application
It is used for finishing rough concentrates of diamond and rare - metal ores : titanium-zirconium, tantalum-niobium, tin-tungsten, rare-earth (monazite-xenotime). Less common are electrical separation of hematite ores, quartz and feldspar, enrichment of potash (sylvinite) ores, extraction of vermiculite , etc.
For the enrichment of minerals, as well as separation by size ( electroclassification ), various electrophysical properties are used: electrical conductivity , permittivity, polarization by friction, heating, etc.
Varieties
Depending on the method of creating particles on a charge and its transfer in the process of electrical separation, there are:
- electrostatic
- crown
- dielectric
- triboadhesive separation.
In electrostatic separation, separation is carried out in an electrostatic field , the particles are charged by contact or induction. Separation by electrical conductivity is performed when particles collide with the electrode (for example, with the charged surface of the drum; in this case, the electrically conductive particles receive the same charge and are repelled from the drum, but the non-conductive ones are not charged). The creation of opposite charges is possible when spraying, hitting or rubbing particles on the surface of the apparatus (triboelectrostatic separation). Selective polarization of the mixture components is possible when heated particles come in contact with the cold surface of a charged drum (pyroelectric separation).
Corona separation is carried out in a corona discharge field, particles are charged by ionization . A corona discharge is created in the air between the electrode in the form of a tip or drift and a grounded electrode, for example, a drum; while the conductive particles give their charge to the grounded electrode. Particles can also be charged by ionization, for example, radiation.
Dielectric separation is carried out by ponderomotive forces in an electrostatic field; while particles with different dielectric permittivity move along different trajectories.
Triboadhesive separation is based on differences in particle adhesion after electrification by friction. Friction is realized when particles are transported on a special lining, in a fluidized bed when particles collide with each other.
Combined processes of electrical separation are possible: corona-electrostatic, corona-magnetic, etc. The relatively low prevalence of electrical separation is explained by the high energy intensity, the need to operate complex high-voltage equipment ( voltage 20-60 kV), and the requirement for thorough preliminary drying of the material, which is difficult to ensure processing plants .
See also
- Electric enrichment
- Magnetic mineral processing
Literature
- Electrical separation (article) // Mining Encyclopedia, TSB Edition, 1984-1990
- Small mountain encyclopedia . In 3 t. = Mala gіrnicha encyclopedia / (In Ukrainian). Ed. V.S. Beletsky . - Donetsk: Donbass, 2004. - ISBN 966-7804-14-3 .