Calcium oxide also called burnt lime acts positive actions at steel-making process.
Since oxides of sulfur, phosphorus, silicon and arsenic are usually some acidic substances, they are chemically combined with some alkaline substances to form relatively stable compounds. The lump calcium oxide is the first choice for the removal of S, P, Si and As, because of it has abundant source and proper price, and can form different compounds with the oxides of S, P, Si and As.
The results of modern metallurgy show that the decarbonization of molten steel is mainly indirect oxidation, where oxygen first oxidizes iron in the middle of molten steel, and the formed iron oxide, while the alkalinity CaO/SiO2 in slag has an important influence on the migration and diffusion of iron oxide in slag to the reaction interface, and increasing CaO in slag is beneficial to the decarbonization of the liquid.
The acidic substances Fe2O3 and SiO2 in the slag tend to react with the alkaline substance MgO in the furnace lining material and erode the furnace lining. After adding calcium oxide, these acidic substances will react with calcium oxide preferentially. Thus using calcium oxide during steel making process can effectively slow down the rate of lining erosion.
