Uses of Ferrosilicon in Steel Plants

Ferrosilicon (FeSi) is an important additive in the steelmaking process. It is mainly composed of iron and silicon, and usually contains 65% to 75% silicon. Its use in steelmaking is mainly reflected in the following aspects: as a deoxidizer, alloying agent, reducing agent and slag-making agent.

Role of Ferrosilicon as a Deoxidizer
During the steelmaking process, oxygen in molten steel will reduce the performance of molten steel and produce defects such as pores and inclusions. Oxygen enters molten steel mainly due to contact with air during smelting and incomplete reduction of iron oxide. Therefore, removing oxygen from molten steel is a crucial step in the steelmaking process. Ferrosilicon is an efficient deoxidizer that reacts with oxygen in molten steel to form stable silicon dioxide (SiO₂), an oxide that is insoluble in molten steel, thereby removing oxygen. Through this reaction, ferrosilicon can not only effectively reduce the oxygen content in molten steel and prevent the formation of oxide inclusions, but also improve the purity and quality of molten steel; in addition, the silicon dioxide slag formed during deoxidation floats to the surface of molten steel, making it easier to remove, making the molten steel purer.

Role of Ferrosilicon as a reducing agent
In some special smelting processes, ferrosilicon is used as a slag-making agent. The main role of the slag-making agent is to help the molten steel form a suitable slag layer, which is conducive to the removal of impurities in the molten steel, stabilize the chemical reaction during the smelting process, and improve the quality of the steel. During the slag-making process, iron can form a slag layer with a low melting point and good fluidity together with other slag-making materials (such as lime, fluorite, etc.). The slag layer can effectively cover the surface of the molten steel, reduce contact with the air, and thus reduce oxidation. At the same time, the slag layer can also absorb impurities in the molten steel and play a purifying role.

Role of Ferrosilicon as an alloying agent
Silicon is an important alloying element in steel and can significantly improve the mechanical and physical properties of steel. Ferrosilicon, as an alloying agent, can introduce silicon into molten steel and produce alloy steel with specific characteristics by adjusting the silicon content. Specifically, silicon has the following contributions to steel:(1)Increase hardness and strength: Silicon can significantly increase the hardness and strength of steel, which is essential for the manufacture of high-strength steel materials. (2)Improve elasticity and toughness: An appropriate amount of silicon can enhance the elastic modulus and toughness of steel, making it less likely to deform and break under impact and load.