METHOD OF PREPARING COAGULANT Russian patent published in 1998 - IPC

FIELD: industrial inorganic synthesis. SUBSTANCE: invention relates to production of iron-aluminum-containing coagulants including dissolution of iron and aluminum oxides from clay or ashes in sulfuric acid. Leaching is carried out for 2 to 4 hr at 100-120 C in solution containing 20-45 % sulfuric acid and 8-50 g/l of common salt. To reduce cost of process and decrease environmental pollution, purified solution from leather stock washing or exhausted pickle solution (both leather production wastes) are utilized as chloride source. Heating and iron ion enrichment of reaction mixture can be achieved by passing direct or alternate current through reaction mixture using steel electrodes. EFFECT: increased oxide isolation degree in etching process. 2 cl, 4 dwg, 1 tbl