Recovery of manganese using molasses as reductant in nitric acid solution

Abstract

The present work provides an investigation of the recovery of manganese from a relatively low-grade ore (37.5% Mn) located in Um-Bogma, Sinai area, Egypt. Several leaching experiments have been performed in HNO 3 acid medium to which molasses as an additive was used to benefit from the reduction action of glucose and fructose. Leaching parameters were optimized as 2.7 M HNO 3 in the presence of molasses (20% of the input weight) in a solid–liquid ratio of 1:12 at 95 °C for 2 h. Under these conditions, the recovery efficiency of manganese attained about 98%, whilst iron dissolution did not exceed 12.9%. The recovery efficiencies of the interesting associated metal values (Cu, Co, Zn, Ni and Cr) have also been investigated. Manganese oxide was recovered from leach liquor in basic media after removal of major gangue impurities by precipitation technique. High purity manganese oxide products namely; (Bixbyite Mn 2O 3) and activated manganese oxide (hausmannite Mn 3O 4) were prepared. The latter was obtained via precipitation in basic media followed by activation using HNO 3 as oxidant and ignition. The obtained products were suitable for several industrial applications besides, ammonium nitrate as added by-product.