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

•A procedure for the recovery of manganese from silicomanganese slag was developed.•Zn, Ni, Co and Cu are treated to remove them as pollutants.•The purified liquor is suitable for electrolysis obtaining α –Mn with a purity of 99.99%.•The developed process is able to recover most of the manganese (94%) in the residue.

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 °C. It was then leached with water, CaO 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. α-manganese is obtained with a purity of 99.99.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide