Abstract: In view of the feasibility of direct alloying using molybdenum oxide in high metal ratio electric arc furnace (EAF), industrial trials on direct alloying using molybdenum oxide under different molybdenum (Mo) contents, hot metal ratios and charging rates were carried out in a 100 t EAF in the current work. The feasibility of the reduction reaction was proved using thermodynamic calculation. Meanwhile, the effect of slag composition and temperature on reaction rate was predicted using kinetic calculation. Without any external reductive agents, with the addition of CaO, the alloy yield and the effect on quality of direct alloying using molybdenum oxide were investigated. It was found that the yield of Mo could be larger than 91 % for both high Mo steel grades and low Mo steel grades. Contrastively, the alloy yield in low Mo steel was larger than that in high Mo steel. And overall, the optimal conditions to reach the highest Mo yield was 760 kg/t steel of hot metal ratio and 9.0 t/min of charging rate of hot metal, under which the yield of Mo could be larger than 93 %, and at the same time high steel cleanliness was ensured, realizing the energy conservation and emissions reduction and valuable economic benefits.

Key words: molybdenum oxide, EAF, direct alloying, hot metal ratio, charging rate of hot metal