#Fe_2O_3(g) + 3CO(g) stackrel(Delta)rarr2Fe+3CO_2(g)#
Steel production is a big, and very capital intensive business. Quantitiies of ferric oxide, and carbon monoxide and heated in a so-called #"blast furnace"#. When I was much younger I was taken to see some of these, and you are very impressed by the scale and the output of these operations. Given the blast furnace, the main ingredients are (i) #"ferric oxide"#; and (ii) #"coke"#, which can be oxidized up to give #CO#, which effects the reduction of the iron ore to iron, and maybe later steel.