GB488008A - A process for the production of cerium compounds - Google Patents

Abstract

Basic cerium sulphate, suitable for use as a white opacifier for enamels, is obtained by diluting with water a sulphate solution containing tetravalent cerium and other cerite earths which is as free as possible from fixed alkalies. Small quantities of ammonia may, however, be added during the precipitation of the basic sulphate, which may be washed with dilute acid to remove traces of didymium compounds. A mixture of cerite hydroxides obtained from a mineral such as monazite sand may serve as initial material, in which case either the hydroxides or the sulphate solution may be treated with oxidizing agents such as hydrogen peroxide, oxygen, or chlorine to convert their cerium content to the tetravalent form; or the sulphate solution may be subjected to anodic oxidation. Precipitation of cerite hydroxides for use in the process may be effected by adding the mixed salts in a solid or dissolved state to the alkali solution, whereby the precipitated hydroxides may be readily washed free from alkali. The basic sulphate may be calcined at 800-1100 DEG C. to yield the oxide, and the usefulness of both sulphate and oxide as an opacifier may be improved by adding small amounts of a basic alkali or alkaline-earth compound, alumina, silica, or an alkali silicate.