Smelting of leached sea nodule residue blended with manganese ore for recovery of manganese

Abstract

The present work describes the experimental studies carried out for utilization of leach sea nodule residue, generated from Reduction roasting - Ammoniacal leaching of sea nodules, for silicomanganese production. Owing to lower manganese content and unfavorable Mn/Fe ratio, leach residue was blended with manganese ore to maintain the Mn/Fe ratio suitable for standard grade silicomanganese alloy production. Smelting of blended charge mix was carried out in 50 KVA DC arc furnace and effect of parameters such as blending ratio, silica addition, holding time etc., on composition of alloy and metal recovery were studied. It was found that charge mix prepared with residue to Mn ore mixing ratio of 1:0.8 and 1:0.6 produced standard grade silicomanganese. The holding time was found to have significant effect on silicon content of silicomanganese alloy which increased with increasing holding time. Holding time also facilitated the good separation of alloy and slag and thereby increased the recovery of metals. The recovery of manganese was 70% with 60 min. holding time. It was observed that the blended charge material should have the Mn/Fe ratio of >3.5 and Mn/Si <2 to produce standard grade silicomanganese alloy.