Blast furnace

• Step 1 – Hot air (oxygen) reacts with the coke (carbon) to produce carbon dioxide and heat energy to heat up the furnace.

  C + O2 → CO2

  Step 2 – More coke is added to the furnace and reduces the carbon dioxide into carbon monoxide, a good reducing agent.

  CO2 + C → 2CO
• Step 3 – iron oxide is reduced.

  iron oxide + carbon → iron + carbon dioxide

  2Fe2O3 + 3C → 4Fe+ 3CO2

  • In this reaction, the iron(III) oxide is reduced to iron, and the carbon is oxidised to carbon dioxide.
  • In the blast furnace, it is so hot that carbon monoxide can be used, in place of carbon, to reduce the iron(III) oxide:

  iron oxide + carbon monoxide → iron + carbon dioxide

  Fe2O3 + 3CO → 2Fe + 3CO2
• Removing impurities:

  Step 4- The calcium carbonate in the limestone thermally decomposes to form calcium oxide.

  calcium carbonate → calcium oxide + carbon dioxide

  CaCO3 → CaO+ CO2

  Step 5- The calcium oxide then reacts with silica (sand) impurities in the haematite, to produce slag – which is calcium silicate. This is separated from the iron and used to make road surfaces.

  calcium oxide + silica → calcium silicate

  CaO + SiO2 → CaSiO3
• Oxidation- This is the process where a substance is gaining oxygen during a chemical reaction
• Reduction- This is the process in which a substance loses oxygen in a chemical reaction
• Raw materials and why they are needed:

  • Iron ore- It is the source of iron
  • Coke- Acts as a fuel + acts as a reducing agent
  • Hot air- Heat which stimulates the reaction+ produces oxygen gas to start reaction
  • Limestone- Removes the impurities