A simulation study on the direct carbothermal reduction of SiO2 for Si metal

The direct carbothermal reduction of SiO2 to Si metal was simulated as a function of mole ratio of SiO2, SiC and C in the temperature range of 0–3000 °C by using a thermodynamic calculation of Gibb’s free-energy minimization. In the SiO2–C system, the silicon metal was formed from the 1250 °C and completed at 1500–2000 °C with the excess amount of C. By the addition of SiC in SiO2–C carbothermal reduction system, complete conversion of SiO2 to Si could be promoted through the lowering the reaction temperature and the excess carbon. Methane gas was efficient reducing agent of SiO2 to form Si metal at around 2000 °C, while H2 and CO could not reduce SiO2 to Si at any conditions. The simulated results were consistent with the experimental works carried out in the arc furnace.