What Is FeSi
May 15, 2026
I. Basic Concepts of Ferro silicon
Ferro silicon is an alloy primarily composed of silicon and iron, typically with a silicon content between 15% and 90%, the remainder being iron and small amounts of impurities (such as aluminum and calcium). It appears as silvery-gray lumps or granules, and is hard and brittle. Ferro silicon is mainly produced through an electric furnace reduction process, reacting silica sand (SiO₂), coke, and iron ore (or scrap steel) at high temperatures.
Ferro silicon is classified into several grades based on its silicon content. For example:
FeSi75: Silicon content 72%-80%, commonly used as a deoxidizer in steelmaking;
II. Main Uses of Ferro silicon
Iron and Steel Smelting: Ferro silicon is an important deoxidizer and alloying additive in the steelmaking process. Adding it to molten steel effectively removes oxygen and increases the strength of the steel. Statistics show that approximately 3-5 kg of ferro silicon is consumed per ton of crude steel (data source: China Iron and Steel Association).
Foundry Industry: Adding ferro silicon to cast iron improves fluidity and reduces porosity defects. Gray cast iron typically requires the addition of 1%-3% ferro silicon.
Other applications: Ferro silicon can also be used to produce magnesium metal (via the Pidgeon process), prepare silicone materials, and even as a raw material for welding electrode coatings.
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