Magnesium salt removal from manganese electrolyte via low-temperature crystallisation

Abstract

ABSTRACT In the electrolytic manganese industry, magnesium accumulation in the electrolyte is detrimental to production systems. Therefore, in this study, magnesium was removed from manganese electrolytes via low-temperature crystallisation. The Mg2+ concentration was reduced from 43.00 to 23.33 g L–1 at the optimal experimental conditions: crystallisation temperature of −5°C, crystallisation time of 1 h, H2SO4 concentration of 80 g L–1, whereas the Mn2+ concentration was minimally affected. The resulting crystal products were primarily composed of Mg(NH4)2(SO4)2·6H2O and a small amount of Fe(NH4)2(SO4)2·6H2O. This process does not require the addition of a precipitant during crystallisation, therefore considerably reducing the magnesium removal cost and facilitating clean production.