Iron and steel

Calcium carbonate is used in the iron and steel industry as a smelting aid, reducing the melting temperature of iron and helping to reduce it, in addition to its interaction with impurities accompanying the raw material such as silica and alumina, forming slag by the interaction of calcium oxide with these oxides, while the carbon dioxide produced by the reducing atmosphere in the furnace is transformed into carbon monoxide, which, as a reducing agent, contributes to removing oxygen from iron oxides to reduce them to metal (iron). Therefore, the limestone used must contain as little as possible of silica, alumina and sulfur oxides.