GB1222508A - Improvements in or relating to the separation of minerals - Google Patents

Abstract

1,222,508. Purifying clay. ENGLISH CLAYS LOVERING POCHIN & CO. Ltd. 24 April, 1968 [3 April, 1967], No. 15238/67. Heading B2H. A mineral impurity is separated from a crude clay mineral by adding to an aqueous slurry of the crude clay mineral (a) a hydrophobic collector which is selectively adsorbed on to the mineral impurity and (b) a non- polar organic liquid in an amount equal to 5 to 50% by volume of the aqueous slurry, agitating the resultant mixture to effect mixing of the organic and aqueous phases without a stable emulsion being formed, and thereafter separating the organic and aqueous phases so that the mineral impurity, which is concentrated in the organic phase can be collected. The hydrophobic collector may be oleic acid, an amine or petroleum sulphonate. The non-polar organic liquid may be a paraffin, benzene, petroleum spirit or carbon tetrachloride. The collector and the organic liquid are preferably mixed together before being added to the aqueous slurry. The mineral impurity on entering the non-polar organic liquid will either float or sink depending whether the liquid is lighter or heavier than water. Separation of the two phases may be effected by gravity or by centrifugal force using a cyclone or centrifuge. Before the addition of the organic liquid, the slurry may have its solids content adjusted to 5-25% by weight and its pH raised to an alkaline value by the addition of an alkali, e.g. ammonium hydroxide solution. A deflocculant, e.g. sodium silicate may also be added to deflocculate the clay. Types of clay mentioned include: china clay and kaolin. Impurities specified are tourmaline and titania. An example of apparatus that may be used comprises a mixing vessel 1 containing a reciprocating agitator in the form of a perforated disc 2 on a shaft 3. The contents of the vessel 1 may be discharged into a separating funnel 5 for the separation by decanting of the aqueous and organic phases.