Primary smelting: the charge is melted, dephosphorized, decarburized and main alloyed in an oxidizing atmosphere. Therefore, the steelmaking process is divided into two steps: primary refining and refining. The steelmaking process in which the primary molten steel in a steelmaking furnace (converter, electric furnace, etc.) is transferred to another vessel for refining, also called secondary metallurgy. The reduction period has been canceled in high power and superpower EAF steelmaking operations. Its main task is to make reducing slag for diffusion, deoxidization, desulfurization, chemical composition control and temperature adjustment. In the operation of EAF, the period from the end of oxidation to the end of tapping is usually called reduction period. In the process of steelmaking, some elements and compounds harmful to the quality of steel are selected into the gas phase or discharged or floated into the slag through chemical reaction through slagging and other methods, so that they can be excluded from the molten steel. With the development of off furnace refining technology, the oxidation refining of EAF mostly moves to ladle or refining furnace. In order to ensure the purity of steel, the amount of decarburization is required to be more than 0.2%. Decarburization is an important process in the oxidation stage. The main tasks of the oxidation period are to oxidize the carbon and phosphorus in the molten steel, to remove the gas and inclusions, and to heat the molten steel uniformly. It is also believed that it starts from blowing oxygen or adding ore to decarbonize. The oxidation period of EAF steel-making usually refers to the process stage from the melting and cleaning of furnace burden, sampling and analysis to the completion of slag removal. The task of the melting period is to melt and heat up the charge as soon as possible, and make the slag in the melting period. The melting period of EAF steelmaking is from the beginning of power on to the end of the melting of all the trace materials in the furnace, and from the end of molten iron blending to the end of the melting of all the materials in the open hearth steelmaking. The melting period of steelmaking is mainly for open-hearth and electric furnace steelmaking. Generally, the phosphorus content of ordinary steel is not more than 0.045%, and the phosphorus content of high-quality steel is less. The higher the carbon content in steel, the more serious the brittleness caused by phosphorus. The steel with more phosphorus is easy to crack when it is used at room temperature or lower, which is called "cold brittleness". Phosphorus is one of the harmful impurities in the steel. Pool stirring can be realized by means of gas, mechanical, electromagnetic induction and other methods.Ĭhemical reaction to reduce phosphorus content in molten steel. For example, when smelting with the single slag method, the oxidation slag must be removed at the end of oxidation when reducing slag is made with the double slag method, the original oxidation slag must be completely discharged to prevent phosphorus return, etc.Įnergy is supplied to the molten metal pool to make the molten metal and slag move, so as to improve the dynamic conditions of the metallurgical reaction. For example, the purpose of oxygen blowing operation is to generate slag with enough fluidity and basicity, which can transfer enough oxygen to the metal surface, so as to reduce the sulfur and phosphorus below the upper limit of planned steel grade, and minimize the amount of splashing and slag overflowing during oxygen blowing.Īccording to different smelting conditions and purposes, the operation of slag discharging or raking is adopted in the process of EAF steelmaking. Slag making is an operation to adjust the composition, basicity, viscosity and reaction ability of slag in steel and iron production. The operation of adding raw materials such as molten iron or scrap steel to the electric furnace is the first step of the steelmaking operation of the electric arc furnace.
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