Talc Treatment and Processing
The basic methods of talc processing at mining, apart from selective recovery, is the manual sorting of material. In this method, in addition to monitoring of contamination by silica, carbonates or pyrites, the monitoring of color differences in the raw material is being used as a distinguishing criterion too. In the countries with the higher wage scale, the manual sorting is being substituted by optical sorting, which reliably works in the grain sizes from > 6 – 8 mm. The maximal size of grains sorted ranges between 40 to 120 mm.
As for fine grains, the flotation is being used in addition to standard procedures of dividing by density. The hydrophobic talc floats without a collector only with the foam-making addition acting. Should the process procedure be hydrophilic, no problems occur; these two minerals do not separate in the flotation process only in presence of graphitic particles/material.
The concentrates are both, dry and wet ground. The standard extent of grain sizes up to 63 my is being reached by spherical, cylindrical and centrifugal pendulum mills. The up-to-date centrifugal sorting machines/separators (basket) enable keeping very sharp granulometric composition of grinding products.
The finest dry grinding up to < 1 my is being achieved via the current mill, and the air, the hot air or the steam can act as the medium.
Since the talc is hydrophobic and the fine material are hardly dispersible, these products are occasionally compacted (usually designated as pellets), where, by rolling – sample pressing with water – the material is pressed into dry bricks. The material such treated is more easily dispersible and is used in e.g. paper industry to liquidate the harmful resin.