Recovery of manganese from silicomanganese slag by means of a hydrometallurgical process

A hydrometallurgical process is proposed in this paper to recover manganese from silicomanganese slag. The paper reports the digestion-leaching experiments and precipitation and electrowinning assays to recover Mn from this residue. Silicomanganese slag was first treated with sulfuric acid in a furnace at 200 degrees C. It was then leached with water, Cab and KOH, and finally filtered to dissolve the manganese. Sulfuric liquor needs a purification step in order to remove Zn, Ni, Co and Cu. Na2S was used to remove pollutants, a 5% excess with respect to the stoichiometric amounts of sulfide required for the reaction being employed for this purpose. The purified liquor is suitable for electrolysis. alpha-manganese is obtained with a purity of 99.99. (C) 2015 Elsevier B.V. All rights reserved.