GB617011A - Methods of separating materials of different specific gravity - Google Patents

Abstract

In a heavy media sink and float separation process in which the solid phase of the medium is a finely divided magnetizable solid, the material to be treated is introduced into the upper layers of the separatory fluid in a vessel in which an adjustable upward current is produced to remove floating particles, an intermediate fraction is withdrawn from below the overflow but sufficiently high to ensure freedom from high gravity particles and a heavy fraction obtained from the bottom of the vessel, as described in the parent Specification, but in which the small sizes -0.1 to -0.15 inch fraction need not be concentrated and may be partly removed with slimes by classification; both heavy and intermediate fractions are drained and washed to give intermediate and heavy concentrates, the drainings, washings and fines fraction, preferably after the removal of non-magnetizable solids, being subjected to a magnetic separation to remove magnetizable solids which, after demagnetizing, are reused in the separatory fluid. The raw feed may be crushed, hydraulically classified and treated in a separatory cone to produce light fines, intermediate and heavy fractions. The light fines with washings and drainings from the screening of the intermediate and heavy fractions are collected and treated in a magnetic thickener-separator, the clean magnetic particles, after demagnetization, being returned to the system, the non-magnetic particles and water being discarded.