Recovery of manganese from ferruginous manganese ore using ascorbic acid as reducing agent

Abstract Being a green and mild acid along with remarkably high solubility for several base metals, ascorbic acid has been used as both leaching agent and reducing agent for the recovery of metals from primary and secondary sources. In the present investigation, ascorbic acid was tested as reducing agent in the presence of sulfuric acid for the leaching of manganese from low grade ferruginous manganese ore. The optimization of the leaching conditions has been comprehensively investigated with respect to H2SO4 concentration, temperature, pulp density, ascorbic acid dosage and agitation speed. Quantitative leaching of manganese was observed under the following optimized conditions: 1 M H2SO4 concentration, 0.070 M ascorbic acid concentration, 70 g/L pulp density, 60 °C leaching temperature, 800 rpm stirring rate and 300 min of reaction time. The leaching kinetic of manganese was evaluated based on the shrinking core model and further validated by SEM and XRD analysis of manganese ores before and after leaching. After further purification of the leach solution, a high purity of 99.95% α-Mn2O3 have been synthesized. The present process therefore deals with achieving the effective recovery of value added product from low grade ferruginous manganese ore.