Preparation of rare earth-silicon-iron alloy by metallothermic reduction

Abstract

An improved process based on metallothermic reduction was investigated to achieve higher rare earth recovery and a better grade of rare earthsilicon alloy than that produced by the commercial submerged arc method. The process involved reduction of mixed rare earth oxides with a mixed ferro-silicon and aluminium reductant in presence of a CaOMgO or CaOCaF 2 flux which prevented loss of rare earth oxide into the slag phase. The smeltings on 5 kg of alloy per batch scale were carried out in an induction furnace at a temperature of 1500–1550 °C. Rare earth-silicon-iron alloy products containing more than 50% REM, corresponding to over 80% rare earth recovery, were achievable in this procedure.