GB633008A - A process for the treatment of complex lithium compounds - Google Patents

Abstract

Complex lithium compounds containing another alkali metal, e.g. lepidolite and dilithium sodium phosphate, are subjected, in aqueous medium, at a temperature above 212 DEG F. and superatmospheric pressure, to the action of a soluble simple lithium compound, e.g. the chloride, nitrate, sulphate, perchlorate, acetate or hydroxide, or of a hydroxide of a multivalent metal soluble in the reaction medium, e.g. of calcium, barium, strontium, magnesium, zinc, aluminium, iron, nickel or cobalt, or a mixture thereof, whereby to produce an insoluble lithium compound free from other alkali metals, viz. lithium phosphate or, say, lithium calcium phosphate, and when hydroxides are used, a solution of caustic soda or potash. The solubility of the hydroxides of the five last-mentioned metals may be increased by adding caustic soda, ammonia, ethyl or isopropyl alcohol, diethylene glycol, &c. Pressures of from 10 to 800 lbs. per square inch with corresponding temperatures are specified. The separated lithium compound is converted into a soluble lithium salt by treatment with calcium, magnesium, barium, strontium chloride, nitrate, perchlorate, acetate, &c. or with salts of zinc, aluminium, zirconium, iron, nickel or cobalt in aqueous medium to which may be added ethyl or isopropyl alcohol, diethylene glycol, &c. An elevated temperature and pressure may be employed. A lithium salt is produced from the separated solution by crystallization. Specification 642,034 is referred to.