Effect of manganese ore blends on performance of submerged arc furnace for ferromanganese production

Abstract

Manganese ore blends are used in ferromanganese production. The blend composition controls the operational performance of submerged arc furnace. A case study has been carried out at FAP, Joda, Tata Steel to better understand the process. The results of experiments revealed that the phase decomposition and decrepitation of Mn ore at low temperatures (500–900°C) in the upper part of the furnace increased the furnace top temperature and thereby promoted agglomeration of the charge, which caused the violent eruptions in the furnace. The root cause of the problems in reaction zone (bottom part) of the furnace was changes in the composition of slag, i.e. low silica and high alumina, which was also due to selection of Mn ores in the blends. Various options for silica addition were examined and compared. The pretreatment of the Mn ores and use of synthetic slag for silica adjustment options were identified to overcome the operating problems and to utilise the captive Mn ores.