Manufacture of manganous sulfate solutions

In a process for producing manganese sulfate solutions containing low levels of potassium impurity from manganese ores containing potassium impurity for use in the manufacture of electrolytic manganese dioxide, said process including reducing said manganese ore, combining said reduced ore with an aqueous acid solution selected from the group consisting of aqueous sulfuric acid and spent aqueous electrolyte containing sulfuric acid and digesting said combination at elevated temperatures in the presence of ferric ion to produce a manganese sulfate solution and a particulate potassium-iron salt byproduct the improvements which comprise:

• A. contacting a portion of said potassium-iron salt byproduct, with a fresh combination of said reduced ore and aqueous acid to form a mixture, said mixture having a solution pH ranging from about 0.5 to about 3.5 and
• B. digesting the mixture of said fresh combination and said salt byproduct at elevated temperatures to produce a manganese sulfate solution and to enhance the reaction between the potassium impurity and ferric ion and the removal of said potassium impurity as potassium-iron salt byproduct from the manganese sulfate solution.