Essential deoxidizer in steelmaking (precipitation and diffusion deoxidation) and alloying agent.
Silicon ranges quoted in the article: general steel 0.15–0.35%; structural 0.40–1.75%; tool 0.30–1.80%; spring 0.40–2.80%; stainless acid-resistant 3.40–4.00%; heat-resistant 1.00–3.00%; silicon steel 2–3% or more.
About 3–5 kg of 75% FeSi consumed per tonne of steel.
75% FeSi melting point 1300 °C.
Foundry: inoculant for nodular cast iron; prevents carbide, promotes graphite precipitation and spheroidization.
Other listed uses: reducing agent for low-carbon ferroalloys; ferrosilicon powder as a suspension phase in mineral processing; electrode coating; high-silicon FeSi as a route to semiconductor-pure silicon and silicone chemicals.
Safety: FeSi can contain phosphide; if damp, phosphine may be released in storage or transport.