Design of Electric Arc Furnace and Secondary Refining
Electric arc furnace (EAF) is an effective tool for the production of molten steel from scrap steel alloy or pure metals. By controlling the parameters and characteristics of the electric arc, such as current, voltage, and arc angle, production of the desired materials is possible. Generally, the EAF is used for the melting of scrap steel for the production of alloy steel, which can be further heat treated, gas formed, and forged to obtain the desired product.
A typical process of steelmaking by electric arc furnace includes the melting of scrap steel, the addition of alloying agents, and the secondary refining process, also known as ladle refining. During the EAF process, the molten steel is produced at high temperatures; the primary objective of the secondary refining process is to further improve the quality of the molten steel.
The secondary refining process generally includes the introduction of elements, such as oxygen, nitrogen, and carbon, which are necessary to change the steel chemistry in order to refine and homogenize the steel in the molten steel. In addition, the secondary refining process is used to reduce the levels of inclusions or impurities present in the molten steel.
In order to control the thermal conditions in the EAF and improve the quality of the steel, additional steps, such as vacuum degassing, ceramic and graphite filtration, and pre-oxygen blown lancing, are often used. The general technique of combining pre-oxygen blew lancing with ceramic and graphite filtration is often referred to as the pre-oxygen blown and secondary combination blowing (POBSC) technique.
POBSC is a very effective secondary refining process, which involves the introduction of oxygen, nitrogen, and carbon to the molten steel in a single operation. This process utilizes a high pressure lance containing a combination of oxygen, nitrogen, and carbon, which is inserted into the liquid steel in the EAF. The oxygen, nitrogen, and carbon, in combination with the lance create a chemical reaction in the molten steel, which provides improved quality of the molten steel.
The POBSC technique is used in combination with the other secondary refining processes, such as vacuum degassing and ceramic and graphite filtration in order to produce high quality steel products. It has been found that POBSC can reduce the overall level of sulfur, improve the surface finish of the steel, reduce the hardness, and also improve the impact strength and ductility of the steel products.
By utilizing the POBSC secondary refining process in combination with the other secondary refining processes, the quality of the steel products produced can be improved significantly. This technique is particularly beneficial for the production of highly alloyed steels or steel with improved machinability.
In conclusion, the electric arc furnace is an effective tool for the production of molten steel from scrap steel alloy or pure metals. The use of the secondary refining process, such as POBSC, as part of the overall steelmaking process is beneficial in providing improved quality of steel products. Thus, by utilizing the POBSC technique, it is possible to produce high quality steel products in an efficient manner.
