What is the role of refining slag in steelmaking?

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Refined slag refers to a technique in which raw materials are mixed in certain proportions and with specific particle sizes, then heated below their melting points to cause them to sinter together, before being crushed into granular form for use. The main components are CaO-CaF2-based, CaO-Al2O3-based, and CaO-Al2O3-SiO2-based. In terms of their morphology, the refining slags are mainly of two types: sintered type and pre-melted type. Pre-melted refining slag refers to a type of refining slag in which raw materials are mixed in certain proportions and then melted into a liquid state using high temperatures in specialized equipment, at temperatures above the melting point of the slag mixture; after cooling and crushing, it is used in steelmaking. Sintered refining slag has a more uniform and stable composition, as well as a faster melting rate, but its cost is relatively higher. Additionally, due to its low density and numerous pores, sintered slag tends to absorb gases during the refining process. Refining slag possesses efficient deoxidization and desulfurization capabilities in steel refining processes; it enables the reduction of sulfides and oxides in molten steel to very low levels. It has strong desulfurization and deoxidization effects, and no backflow phenomenon occurs.