Steel is made by pig iron produced by blast furnace and DRI sponge iron and scrap as raw material, using different melting methods into steel, which include converter steelmaking method, open hearth furnace, electric arc furnace steelmaking etc. three categories. All the three kinds of steel-making process can meet the general quality requirements of steel users.
In order to meet requirements for higher quality and more varieties of high-grade steel, there has a variety of handling methods for molten steel outside of the furnace (also known as refining), such as blowing argon, vacuum degassing and desulfurization outside of furnace etc. By additional refining processing of molten steel produced from converter, open-hearth furnace and electric arc furnace etc., we can get advanced steel grades.
For some high-quality steel for special purpose and special requirements, if further processing outside of furnace still can not meet requirements, then we will use a special method for steel refining, such as ESR, which is a complicate refining process need secondary refining. After got molten steel from converter, open-hearth furnace or electric arc furnace steel smelting, do casting for forging to make it as electrode, then start secondary refining by heating with remelting slag.