steelmaking materials iron and silicon

Raw materials are the material basis for steelmaking. The quality of raw materials directly affects the quality of the steelmaking process and products. The quality of raw materials not only means that the chemical composition and physical properties should meet technical standards, but also require that their chemical composition and physical properties remain relatively stable. Mass production practice has proved that ensuring the stability of the chemical composition and physical properties of raw materials is an important way to automate the smelting process and improve various technical and economic indicators. Therefore, in order to achieve high quality and high output of steel, strict requirements on raw materials must be made.



The most basic raw material used in steelmaking is molten iron. In the converter steelmaking process, molten iron generally accounts for more than 70% of the furnace volume; electric furnace steelmaking generally uses scrap steel as the raw material, and modern electric furnaces also use molten iron as the metal material. The molten iron volume of individual electric furnace plants can be as high as 60%. The physical heat and chemical heat of molten iron are the basic heat sources of steelmaking, so there should be certain requirements on the composition and temperature of molten iron. Whether the composition and temperature of the molten iron are appropriate and stable has an important influence on the stability of steelmaking operations and the technical indicators of the final product. Electric steel for electric arc furnace uses scrap steel as the basic raw material, and molten iron is mainly used to increase the carbon content of the charge, generally 10%-30% of the iron and steel charge is added. If you lack molten iron, you can add metallurgical silicon carbide to increase the carbon content. Sometimes scrap steel with higher carbon content such as scrap steel ingots and chassis can be used to replace pig iron to reduce costs.

Silicon is one of the important heat-generating elements in steelmaking. The molten iron contains high silicon, which increases the source of heat in the furnace. According to the calculation of heat balance, every time the Si content calculated by weight in the molten iron increases by 0.1%, the amount of scrap added can increase by 1.3-1.5%. This is also the reason why Metallurgical silicon carbide is often added to scrap smelting. In the steelmaking process, silicon is almost completely oxidized, and the molten iron contains too much silicon. Under the same slag alkalinity, it will inevitably increase the consumption of lime, increase the amount of slag, and increase the loss of iron in the slag. The large amount of slag is also easy to cause splashing. At the same time, the SiO2 in the slag increases, which intensifies the corrosion effect on the furnace lining and reduces the service life of the furnace body. If the Si content in the molten iron is too low, the amount of scrap steel will be reduced, and it is not easy to form slag. If the amount of slag is small, it is not good for dephosphorization and desulfurization. Therefore, in order to quickly make slagging and discharge slag, the molten iron is required to have a proper Si content. If the Si content is insufficient, you can add Silicon Briquette, Metallurgical Silicon Carbide and other products to increase the Si content to 0.4%-0.8%, which is a reasonable range suitable for steelmaking.