Method of obtaining granulated and defluorated phosphogypsum

摘要

A combined method for granulation and defluoration of phosphogypsum, suitable for subsequent fluidized bed disassociation to lime and sulphur dioxide is described. The new phosphogypsum, obtained from phosphoric acid production, containing residual combined fluorine, is dried to reduce its residual water. It is moistened with sulfuric acid and aqueous solutions of binding agent additives and then granulated. The granules are heat-treated at temperatures between 170 DEG C. and 700 DEG C. During the heat treatment the residual fluorine residue is volatilized and the granules increase in strength sufficient for use in subsequent fluidized bed treatments.