Effect of Varying SiO Contents on Si and FeSi Production

During primary silicon (Si) production in submerged arc furnaces, silicon carbide (SiC) is one of the main intermediate compounds generated due to the interaction of carbon materials and silicon monoxide (SiO (g)). A complete conversion of SiC from carbon materials is significant and has great importance on the Si yield. The SiO reactivity of carbon materials, their ability to form SiC is thus important for Si-production. The SiO reactivity depends on the properties of carbon materials such as porosity, surface area and cell wall thickness. Their effect on SiO-reactivity has here been studied for charcoal, coal and char and compared with CO2 reactivity for the materials. The reactivity of carbon materials has been measured by the SINTEF SiO reactivity test, that takes place at low partial pressure of SiO (pSiO < 0.01 bar) and at 1650 °C. The test has been updated and the reliability of the improved set up are discussed. In the industrial Si process, the process gas, which is a mixture of SiO and CO, with higher partial pressures of SiO than 0.01 bar can be in contact with unreacted carbon. The effect of partial pressure of SiO on SiC conversion of carbon have been investigated and is discussed. In addition, the correlation between SiC surface crystal formation and CO2 reactivity of the selected carbon materials have also been investigated.