In addition to the blast furnace process for production of pig iron, smelting reduction processes are also used in which the iron ore is reduced to pig iron.
The smelting reduction process (Corex, Finex) is a combination of direct reduction and smelting process to produce molten pig iron, the quality of which corresponds to blast furnace pig iron. The ore is first reduced to sponge iron in a two-stage process and subsequently melted with coal and oxygen to form pig iron. The energy required for the melting process is provided by the combustion of coal (not coked). This produces large amounts of carbon monoxide as exhaust gas, which is used as a reducing gas.