Beneficiation of low-grade Manganese ore from Tirodi Mines, Madhya Pradesh

Abstract

A low-grade manganese ore sample from the dumps at Tirodi Mines, Madhya Pradesh, consisting of braunite, psilomelane, garnet and quartz as the principal constituents, assayed 27.39 percent Mn, 33.4 percent SiO2, 7.47 percent Fe and 0.36 percent P. Jigging followed by magnetic separation yielded a concentrate assaying 38.78 percent SiO2 and 0.37 percent P, with a manganese recovery of 72 percent. Straight magnetic separation recovered 60.9 percent manganese in a concentrate of grade 40.77 Mn, 15.11 percent SiO2,13.44 percent Fe and 0.31 percent P. It was not possible under the conditions tested to float selectively the manganese minerals. Dry magnetic separation of the sample at -20 +35 and -35 mesh, followed by wet magnetic fraction at -100 mesh and by electrostatic separation of the feebly magnetic fraction gave the best results viz. a concentrate of grade 45.41 percent Mn, 0.27 percent P and low iron with a recovery of 51 percent manganese. This treatment yielded also a secondary concentrate of grade 35.24 percent Mn, 23.19 percent Fe and 0.08 percent P recovering another 20.8 percent of manganese. Straight electrostatic separation recovered only 43.7 percent Mn. Tabling followed by electrostatic separation of the table concentrate gave a manganese recovery of 46.6 percent in a product assaying 43.09 percent Mn. It was observed that electrostatic separation of garnet from the manganese minerals, which neither gravity nor magnetic separation methods could do efficiently. Heating of the concentrates near to the sintering temperature generally improved their manganese content by about 3 units (percent Mn).Phosphorus appears to be intimately associated with the manganese minerals and cannot be generally brought below 0.21 percent in the concentrate.