Sodium fluosilicate recovery from wet process

摘要

Na fluosilicate is recovered from wet process phosphoric acid contg fluosilicic acid by (1) adding sufficient of a Na cpd to ppt the fluosilicic acid as Na fluosilicate to obtain Na fluosilicate crystals and purified phosphoric acid free of dissolved fluosilicic acid (2) adding a Na cpd to a part of the purified phosphoric acid in an amount which does not cause precipitation of dissolved Fe and Al, to form an aqs. soln contg phosphoric acid and Na dihydrogen phosphate, and (3) adding this aqs. soln to the wet process phosphoric acid to form Na fluosilicate crystals. Large crystals are produced and high purity Na fluosilicate may be obtained. Concn. of the phosphoric acid is not lowered.