Extraction by electroflotation of iron, chromium and aluminium hydroxides from aqueous solutions of sodium chlorides and sulphates in the presence of Mg2+, Ca2+ and surfactants of different types

Abstract

This paper examines an electroflotation process in which iron hydroxides are recovered from chloride-sulphate solutions in the presence of surfactants of different types, as well as calcium and magnesium cations used as reagents. It was found that calcium and magnesium cations lower the recovery of iron hydroxides by 30 to 40%. Introduction of surfactants intensifies the recovery of iron (III) hydroxides making it reach 89 to 98%. It was found that the anionic surfactant NaDDS produces a positive effect on the recovery of chromium (III) hydroxides by electroflotation by raising the recovery rate by 30 to 40% and expanding the effective pH range to 9. NaDDS improves the recovery of the mixture of iron, chromium and aluminium hydroxides in electrolytic solutions (10 g/l). Water treatment procedures are described aimed at removing iron (II, III) ions and the iron/chromium mixture.