Preliminary screening of purification processes of liquor leach solutions obtained from reductive leaching of low-grade manganese ores

In this paper, the purification of liquor leach solutions obtained from low-grade manganese ores leached by carbohydrates in sulfinic medium was studied and developed. In particular, purification was made acting directly during the leaching process (simple or hydroalcoholic medium) and also using different down-stream purification technologies such as precipitation, solvent extraction and adsorption onto active carbon. The complexity of the aqueous system (due to the high concentration and heterogeneity of inorganic ionic species, but also to the presence of organic compounds as intermediates of glucose oxidation) affects metal speciation in solution in contrast with theoretical predictions. Leaching performed in hydroalcoholic medium combined with adsorption onto active carbon permits obtaining, after an evaporation phase, a final solution with specification concentrations of manganese, calcium and iron for food-additive production. (C) 2004 Elsevier B.V. All rights reserved.