Blast Furnace Raw Materials 

A blast furnace primarily uses the following raw materials:

1. Iron Ore - This is the primary source of iron. It usually contains iron oxides like hematite (Fe₂O₃), magnetite (Fe₃O₄), and lesser amounts of goethite (FeO(OH)) or limonite (FeO(OH)·nH₂O).

2. Coke - Coke acts as both a fuel and a reducing agent. It's produced by heating coal in the absence of air, which drives off volatile components, leaving behind a high-carbon, ash-containing solid.

3. Limestone (CaCO₃) - When limestone is added to the furnace, it decomposes into calcium oxide (CaO) and carbon dioxide (CO₂). Calcium oxide then reacts with impurities in the ore (like silica, SiO₂) to form slag, which can be easily removed from the iron. 

4. Air (or Oxygen-Enriched Air) - Hot air is blasted into the furnace from the bottom through tuyeres. This air helps in the combustion of coke, producing carbon monoxide (CO) which reduces the iron ore.

5. Sinter: Sometimes, instead of or in addition to raw ore, sintered ore is used. Sinter is produced by heating a mixture of iron ore fines, limestone, and sometimes recycled materials from the steel plant to just below melting point. This agglomeration process makes the material more suitable for use in the blast furnace.

6. Fluxes - Apart from limestone, other fluxes like dolomite might be used to ensure the slag has the correct properties for easy removal.

7. Pellets - These are agglomerates of iron ore fines, fluxes, and sometimes other materials like coke breeze. They provide a more uniform feed into the furnace, which helps in maintaining a stable operation.