Among the many uses of lime in the steel industry, three stand out:
- Lime is used to convert iron into 'pig iron'. In the blast furnace, finely ground or granular limestone (with a low sulfur and alkali content) is used together with finely ground lime to convert ore into pig iron. The pig iron is later processed into steel.
- Lime is used as a fluxing agent in electric arc furnaces and basic oxygen furnaces. Lime removes impurities (silica, phosphorus, sulfur) from the steel being manufactured. The lime fuses with the impurities to form slag, which separates from the steel and is removed. This process improves the quality of the steel.
Lime is also used to enhance the refractory life of the furnaces. The MgO in dolomitic lime reduces the tendency of slag to dissolve the MgO from the furnace refractory