The blast furnace is a shaft furnace and the world's most important iron ore smelting unit. From processed iron ores (mostly oxides) and additives, liquid pig iron is produced in a continuous reduction and melting process. The iron ore is reduced with coke. The energy for the smelting process is produced in the blast furnace by burning coke with preheated, oxygen-enriched air.
The blast furnace operates on the counter-current principle, with the supply of iron ore and coke from the top into the blast furnace and the oxygen-enriched hot air required for the coke combustion process, blown from below via tuyeres. In the furnace, combustion, melting and reduction zones are formed from bottom to top. The iron ore is reduced to pig iron in the reduction zone, which is about 650 to 1100°C hot.
The use of oxygen is particularly effective when the entry system brings about high penetration depth into the coke bed. The aim is to achieve uniform melting of the feed over the entire furnace cross-section without additional wear of the refractory material.