Limestone—A Review with Special Reference to the Iron and Steel Industry

Limestone, Fluorite, and Calcium carbide are the materials used as flux in steel making. For steel making, a superior grade of limestone is required to control slag volume and improve productivity. As per Bureau of Indian Standards (BIS), the specifications of limestone for steel making are: CaO should be 53% minimum, MgO–1.5% maximum, SiO2–1.5% maximum, total sulphur–2% maximum, and Alkalies–0.2% maximum. This grade is available in some quantities in Rajasthan, Himachal Pradesh, and Sikkim. Mostly, these resources are far away from the existing Iron and steel industries or plants, hence, movement from these areas involves high logistics costs. The steel industry imports this material from UAE, Oman, Malaysia, Vietnam and Iran. India has limestone reserves in Andhra Pradesh, Karnataka, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, and Odisha but steel-grade limestone is limited to a few states only. The limestone requirement is about 100 kg per tonne of liquid steel produced. At 255 MTPA crude steel production, the requirement is 25.50 MT. An attempt has been made in the paper to discuss usage, applications, export & import, and demand & supply of steel-grade limestone in India.