How do you make ferrosilicon?
Jul 29, 2025
Ferrosilicon (FeSi) is an alloy of iron and silicon, typically containing 15% to 90% silicon. It is produced in an electric arc furnace through the carbothermic reduction of silica (SiO₂) in the presence of iron sources. Here's a step-by-step overview of the production process:
Raw Materials Required:
Silica (SiO₂) – Usually sourced from quartz or high-purity sand (≥98% SiO₂).
Iron Sources – Can be iron ore (hematite/magnetite), steel scrap, or mill scale.
Carbon Reductant – Typically coke, coal, or charcoal.
Electrodes – Graphite or carbon electrodes for arc furnace operation.
Production Process:
Raw Material Preparation:
Silica, iron sources, and carbon are crushed and mixed in precise proportions based on the desired FeSi grade (e.g., FeSi75 contains ~75% Si).
Charging the Furnace:
The mixture is fed into a submerged arc furnace (SAF), which operates at very high temperatures (1600–1800°C).
The furnace is lined with refractory materials to withstand extreme heat.
Reduction Smelting:
Electric arcs between the electrodes and the charge generate intense heat.
The key reaction is the carbothermic reduction of silica:
SiO2+2C→Si+2CO (gas)
The silicon then combines with iron to form ferrosilicon:
Fe+Si→FeSi
Impurities like Al, Ca, and P form slag.
Tapping and Refining:
Molten ferrosilicon is tapped from the furnace at intervals.
Slag is removed, and the alloy may be refined further (e.g., ladle treatment to adjust composition).
Casting and Crushing:
The molten FeSi is cast into molds or granulated (water-quenched for smaller sizes).
After cooling, it is crushed and sized for sale.
Key Considerations:
Energy Intensive: Requires ~8,000–9,000 kWh per ton of FeSi.
Environmental Controls: CO emissions are captured, and slag is recycled or disposed of safely.
Grades: Common grades include FeSi72, FeSi75 (numbers denote % Si).
Applications:
Steelmaking: Deoxidizer and alloying agent.
Foundry: Modifies cast iron properties.
Magnesium Production: Used in the Pidgeon process.
If you would like to know more about ferro silicon, please email us info@kexingui.com
