GB678978A - Improvements in method of recovering lithium compounds from lithium minerals - Google Patents

Abstract

Lithium-containing ores, e.g. spodumene, are calcined in admixture with an oxide, hydroxide or salt of an oxidic acid of an alkali or alkaline earth metal in amount insufficient to render the compound of lithium materially soluble in water, the calcined material is brought into contact with water containing anions of an acidic radical, and a dissolved lithium compound is recovered. Slaked lime, limestone, dolomite, magnesium oxide, calcium sulphate sodium carbonate, sodium sulphate or several of these compounds may thus be calcined with the spodumene, e.g. in a rotary furnace, or, mixed with coal, in a furnace with a fixed or p moving grate. The reaction may be stopped at the first signs of sintering, although the mass may be completely fused. By way of example, from 0.5 per cent to over 50 per cent, but less than 100 per cent by weight lime reckoned on the spodumene may be used. Extraction may be effected by solutions of sodium chloride, sulphate or nitrate, or calcium chloride or nitrate at elevated pressure and temperature, maxima of 90 atmospheres and 400 DEG C being specified, or by boiling hydrochloric acid solution without superatmospheric pressure. The extract is treated with sodium carbonate to precipitate lithium carbonate, and to regenerate a sodium salt for reuse.