Steel is the key material used for building bridges, skyscrapers, railroads, automobiles, and appliances.
Limestone is used as a fluxing agent in electric arc furnaces and basic oxygen furnaces. Limestone removes impurities (silica, phosphorus, sulfur) from the steel being manufactured. The limestone fuses with the impurities to form slag, which separates from the steel and is removed. This process increases the quality of the steel.
Dolomite is used to enhance the refractory life of the furnaces. The MgO in dolomite reduces the tendency of slag to dissolve the MgO from the furnace refractory.