Silicomanganese production utilising low grade manganese nodules leaching residue

Abstract

The use of washed leached manganese nodules residue (WMNR), generated by reductive roasting ammoniacal leaching of manganese nodule, for production of standard grade silicomanganese (Si16Mn63), via carbothermic reduction smelting in electric arc furnace was described. The lower Mn/Fe ratio of WMNR was improved by its blending with Mn ore. Various parameters, such as Mn/Fe, Mn/Si, coke addition, CaF2 addition and holding time, were varied to optimise process to produce the desired grade of silicomanganese. Under optimised set of conditions, a charge mix with Mn/Fe>3?5 and Mn/Si>2?5 at basicity CaOzMgO)/SiO2} of 0.2 and R ratio {(CaOzMgO)/Al2O3} of 1?8 produced the standard grade silicomanganese in 15 min holding time with .77% Mn recovery. Excess coke (110% of stochiometric amount) in the smelting and CaF2 additions to the tune of 4 wt-% (WMNR–Mn ore blend) during the holding time, improved the metallic yield and manganese recovery.