Lime in the Steel Industry
The North American steel industry is vital to both economic competitiveness and national security. Steel is the key material used for building bridges, skyscrapers, railroads, automobiles, and appliances. Currently there are more than 3,000 catalogue grades of steel available, not including custom grades for specific users. This highly competitive, capital-intensive industry is a major consumer of lime products.
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 increases 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.
In addition to the widespread individual use of our lime and limestone products throughout North America, Graymont is continuing to develop and supply custom blends of these materials. Our goal is to provide products that will assist our steel customers to succeed in this highly competitive industry, maximizing their production and helping them to meet ever-more-stringent quality requirements.