Abstract: A Process for preparing industrial grade manganese carbonate frommanganese mud-a waste from potassium permanganate factory-ispresented. The process comprises three steps:(1) Reducing and leaching the manganese mud with waste pickle liquor as well as precipitating iron, (2) Purification of Pregnant solution, (3) Precipitating manganese carbonate by adding ammonium bicarbonate.
In the first step, if the ratioH⁺/(Fe⁺⁺ in pickle liquor is welladjusted, the leaching of manganese and precipitation of iron may be proceed simultaneously so that the ammount of alkaline used in precipitating iron can be reduced greatly. Na₂S is added to remove other heavy metals.Ammonium bicarbonate is used for producing manganese carbonate in order to avoid the contamination byCa⁺⁺ ion from the water. The pollution of the waste in this process is rather less than that of the pickle liquor and. manganese mud.