Please answer in detail why feco3 is not used in blast furnace?

Dear Student, In blast furnace, smelting of ore i.e. reduction of ore to metal is done. The carbonate ore (FeCO3) is more difficult to smelt than a haematite or other oxide ore. It requires driving off the carbonate as carbon dioxide requires more energy and so the ore 'kills' the blast furnace if added directly. Instead the FeCO3 ore must be calcinated first to form oxide ore and then must be added to blast furnace. Regards