Treatment of effluents containing metallic sulfates comprises an initial precipitation of metals as hydroxides and then precipitation of sulfates as calcium sulfate

摘要

The treatment avoids contamination of the recovered calcium sulfate by first precipitating metals with an addition of ammonia. The process consists of the following stages: (a) addition of ammonia solution to the effluent to obtain ammonium sulfate and precipitate metallic hydroxides Mea(OH)c; (b) separation of the precipitated hydroxides from the effluent solution; (c) addition of Ca(OH)2 to precipitate sulfates in solution as calcium sulfate; (d) separation of the CaSO4 precipitated from the remainder of the effluent.