(1) used as deoxidizer and alloying agent in steel making industry. In order to obtain steel with qualified chemical composition and ensure the quality of steel, deoxidization must be carried out at the last stage of steelmaking. The chemical affinity between silicon and oxygen is very high, so ferrosilicon is a strong deoxidizer for precipitation and diffusion deoxidization. The strength, hardness and elasticity of the steel can be significantly improved by adding a certain amount of silicon to the steel. Therefore, ferrosilicon is also used as an alloy in the smelting of structural steel (containing 0.40-1.75%), tool steel (containing SiO.30-1.8%), spring steel (containing SiO.40-2.8%) and silicon steel for transformers (containing 2.81-4.8%). At the same time, it is an effective new technology to improve steel quality, reduce cost and save iron by improving inclusion morphology and reducing gas element content in molten steel. It is especially suitable for deoxidization of molten steel in continuous casting. The practice shows that ferrosilicon not only meets the requirement of deoxidization in steelmaking, but also has the characteristics of desulfurization, high specific gravity and strong penetration.
In addition, in the steelmaking industry, ferrosilicon powder is often used as a heating agent for ingot cap to improve the quality and recovery of ingot, because it can release a lot of heat at high temperature.
(2) used as inoculant and spheroidizing agent in cast iron industry. Cast iron is an important metal material in modern industry. It is cheaper than steel, easy to melt and smelt, has excellent casting performance and much better seismic resistance than steel. Especially for ductile iron, its mechanical properties reach or approach the mechanical properties of steel. Adding a certain amount of ferrosilicon to cast iron can prevent the formation of carbide and promote the precipitation and spheroidization of graphite. Therefore, ferrosilicon is an important inoculant (helping to precipitate graphite) and spheroidizing agent in the production of ductile iron.
(3) used as reducing agent in ferroalloy production. Not only the chemical affinity between silicon and oxygen is large, but also the carbon content of high silicon ferrosilicon is very low. Therefore, high silicon ferrosilicon (or silicon alloy) is a common reducing agent in ferroalloy industry.
(4) 75# ferrosilicon is often used in the high-temperature smelting of metallic magnesium by Pidgeon process. The magnesium in CaO.MgO is replaced by 75# ferrosilicon. It consumes about 1.2 tons of ferrosilicon for every ton of metallic magnesium produced, which plays a great role in the production of metallic magnesium.
(5) use in other areas. The silicon iron powder treated by grinding or atomizing can be used as a suspension phase in the mineral processing industry. It can be used as coating for electrode in manufacturing of electrode. High silicon ferrosilicon can be used in the chemical industry to produce silicone and other products.
For these purposes steelmaking, foundry and ferroalloy industries are the largest users of ferrosilicon. They consume about 90% of ferrosilicon. Among the different grades of ferrosilicon, the 75% most widely used ferrosilicon is currently used. In the steel making industry, about 1t silicon steel is consumed per production of 3-5kg75% steel.