The chemical formula of iron ore is Fe2O3, which is abundant on the earth. Compared with other types of ore, more iron is produced under the same quality.

Coke is reducible, which can react with air at high temperature to generate CO, and CO is reducible, which can reduce iron in Fe2O3 to elemental iron.

Limestone is mainly used to remove mixed silicide from iron ore and improve the purity of ironmaking.

As a raw material for coking to produce reducing gas CO, air is essential.