A method for removing impurities from zinc sulfate - and / or cadmium sulfate solutions

摘要

Impurities in a solution of zinc or cadmium sulphate, for use in prodn. of electrolytic zinc or cadmium, are eliminated by addition of persulphuric acid which has been hydrolysed, esp. contg. Caro's acid, and pref. hydrolysed so that the ratio of moles of Caro's acid to the sum of the number of moles of H2S2O8, H2SO5 (Caro's acid) and H2O2 produced by the hydrolysis reaction is about unity. Alternatively the Caro's acid may be produced from oleum and H2O2. The sulphuric acid content of the added acid is 10 g/l.