METHOD OF RECYCLING BY-PRODUCTS OBTAINED FROM PRODUCTION OF WET-PROCESS PHOSPHORIC ACID

摘要

FIELD: chemistry. ^ SUBSTANCE: invention can be used in chemical industry. The method of recycling by-products of production of wet-process phosphoric acid involves treating phosphogypsum with fluorosilicate solution, followed by neutralisation of the mixture and separation thereof by filtration. The fluorosilicate solution used is hydrofluorosilicic acid with concentration of 5-12%. The phosphogypsum is first treated with ammonia water with concentration of 8-12% with ratio of components necessary to obtain liquid to solid phase ratio of (1.5-2.5):1 in the suspension. The hydrofluorosilicic acid is taken in stoichiometric amount with respect to the ammonia added before. The obtained mixture is then neutralised to pH 8-8.8 with ammonia and filtered to separate ammonium sulphate solution and a residue which contains calcium fluoride. ^ EFFECT: invention increases the degree of recycling by-products of production of wet-process phosphoric acid. ^ 1 tbl