Hematite: the major ore of iron, iron(Ill) oxide
Blast furnace: a furnace for extracting metals (particularly iron) by reduction with carbon that uses hot air blasted in at the base of the furnace to raise the temperature
Limestone: a form of calcium carbonate (CaCO3)
Mineral: a naturally occurring rock containing a particular compound
Slag: a molten mixture of impurities, mainly calcium silicate, formed in the blast furnace
Reduction of iron ore to iron
carbon oxygen → carbon dioxide
carbon dioxide carbon → carbon monoxide
iron(Ill) oxide carbon monoxide → iron carbon dioxide
Remove impurity
calcium carbonate → calcium oxide carbon dioxide
calcium oxide silicon (IV) oxide → calcium silicate