Carbothermal Reduction Behavior of Micro-silica

Abstract Micro-silica, a predominant byproduct of industrial silicon enterprises, presents a substantial opportunity for recycling within the production of industrial silicon. In this study, we utilized micro-silica procured from an industrial silicon facility and commercially accessible N991 carbon black as experimental materials. We scrutinized the influence of micro-silica and carbon black on the yield and velocity of SiC formation under varying conditions: temperatures of 1625°C, 1650°C, and 1675°C (1898 K, 1923 K, and 1948 K), disparate CO partial pressures, and diverse SiO2 to C molar ratios. Our findings reveal that micro-silica initiates melting at a threshold of 1600°C. At a temperature of 1650°C, the loss rate of SiO is minimized, resulting in the highest reaction matching degree. Elevated temperatures and increased CO partial pressures correspond to accelerated reaction rates. The reaction of molten SiO2 and CO accelerates the carbothermal reduction reaction rate. A harmonious correlation was observed between the SiO2 reactivity of the micro-silica and the SiO reactivity of the carbon black. The reaction between SiO2 and SiC in the molten state increases the weight loss rate and the reaction rate. The optimal agglomerate composition was determined to be mol(SiO2): mol(C) = 1:3.