The following raw materials are required: The principal raw materials are silica (SiO₂) and a source of iron, typically in the form of scrap iron or iron ore. In some cases, reducing agents, such as coke or charcoal, may be included to facilitate the reduction reaction.
Charging the Furnace: The raw materials are meticulously combined and loaded into an electric arc furnace. The proportions are dependent on the desired silicon content of the final product.
Electric Arc Heating: The electric arc furnace generates high temperatures (approximately 1500 to 2000 degrees Celsius or 2732 to 3632 degrees Fahrenheit) by passing an electric current through the charge. The heat generated by the electric arcs melts the raw materials, allowing the reduction reactions to occur.
The reduction reaction is as follows: In the high-temperature environment of the furnace, the silica is reduced by the carbon (from coke or charcoal) in the following reaction:
The reaction between silicon dioxide and carbon results in the formation of silicon and carbon monoxide gas. The equation for this reaction is as follows:
SiO2 + 2C → Si + 2CO Additionally, iron oxides can be reduced as part of this process.
The formation of ferro silicon: As the reaction progresses, ferro silicon is produced in the form of a liquid alloy. The silicon combines with the iron present in the initial charge.
The furnace is tapped in order to: Once the reaction is complete, the molten ferro silicon is tapped from the furnace and allowed to cool. It can then be solidified in moulds to form ingots or cast into other shapes according to customer specifications.
