Process of making manganous sulphate solution with low level impurity of potassium for manufacture of electrolytic manganese dioxide

摘要

Large proportion of available manganese ores contain high proportions of potassium. Electrolytic manganese dioxide (EMD) is manufactured from manganous sulphate obtained from naturally occuring manganese ores. Crystallographically EMD has to be essentially gamma phase and other phases, alpha and beta should be the bare minimum. High potassium content is, however, an obstruction in the way of getting gamma phase EMD. The present invention describes a method of making manganous sulphate solution with low level impurity of potassium from high potassium ores which comprises adding the reduced ore to spent electrolyte containing ferric ions and digesting same at pH 1-2 and temperature of 60 DEG -90 DEG C. for 1-4 hours, and thereafter again adding reduced ore to the digested product till pH is raised to 4-6.