Fixed carbon ratio in silicon production - determined based on desired silicon yield ## Challenges Amount of Si -> analysis of SiO₂ raw materials Amount of C -> analysis of carbon materials, have varying water content, difficult to get right ### Outcomes - balanced -> $\ce{SiO2 + 2C \longrightarrow Si + 2CO}$ - undercoking -> $\ce{SiO2 + C \longrightarrow SiO + CO}$ - not enough carbon - furnace fills with slag - cathodes destroyed - bad tapping - low Si production - high silica dust production - overcoking -> $\ce{SiO2 + 3C \longrightarrow SiC + 2CO}$ - too much carbon - furnace fills with carbide - unintended [[Electrodes|electrode]] movement - electrodes high, raises resistance - hot charge surface - cold bottom -> difficult tapping