Selective Leaching of Iron from Low Grade Ferruginous Manganese Ores of Sandur area, Karnataka for Ferromanganese Production by using Sucrose in Sulphuric Acid Medium

The vast reserves of low grade, ferruginous manganese ores from Deogiri mines, occur in to the well known Sandur greenstone belt in Bellary district, Karnataka. The ore contains 32.40% Mn, 24.49% Fe, 2.79% SiO, and 6.80% Alz03. It was sampled and subjected to physical beneficiation and selective reductive leaching of iron with sucrose (Cl2H,,,0,) in sulphuric acid medium. The aim of the present work is to raise the Mn/Fe ratio of the manganese ore which can be used as a raw materialforferro-manganese production. From XRD analysis and ore microscopic studies it was noticed that the major manganese minerals were pyrolusite, cryptomelane and lithiophorite, and the gangue minerals were hematite, goethite, limonite, manganiferous shales, quartz and aluminous clays. The ore was washed on Wilflev table to reject the possible gangue minerals.
The concentrate obtained from Wilfley table was subjected to selective reductive leaching of iron using sucrose in sulphuric acid medium.The leaching experiments were carried out by varying the parameters like sucrose concentration (1-4g/100cc), time (30-120 minutes), pulp density (5-20%) and temperature (30-80°C) with constant feed size distribution of -200 mesh in all the experiments.
The optimum condition of the total process of leaching obtained are 2g/100 cc of sucrose concentration, 90 minutes of time, 10% by weight pulp density 30 °C of temperature with 82.23% Fe in leached liquor. 74.54% Mn in residue, 9.35% Fe in residue with a Mn/Fe ratio of 7.96.