Steel Story

• To make iron, it is first nece**ary to mine iron ore.
• Iron ore is simply rock with a high concentration of iron within it. Usually the ores are mixed into rocks which contain silica.
• From the table above, it is evident that the iron ores contain oxygen.
• In order to make the iron from the ore, the oxygen must first be removed. This can be achieved using a blast furnace in which a series of reduction reactions occur.
• Ores of iron greater than 5mm can be placed straight into the blast furnace; however these are in short supply and so the iron first goes through agglomerating proce**es (fuse together the smaller lumps of ore) such as sintering or pelletising. These proce**es involve mixing together the iron with controlled quantities of fluxes.
• Iron, limestone and coke are fed into the top of the blast furnace. The limestone is melted to become the ****, which removes impurities such as sulphur.
• The main fuel used in the blast furnace is coke. This is made by heating carbon in the absence of oxygen. The coke is burnt in heated air (1,100 K to 1,600K) and then blown into the furnace at the bottom. The coke reacts with oxygen in the hot air blast to form carbon monoxide:
  2C_(s) + O₂(g) 2CO_(g)
• Hydrocarbons can also be used as a fuel, and these react similarly to produce carbon monoxide and hydrogen.
  CH_4(g) + 0.5O_2(g) CO_(g) + 2H_2(g)
• The gases move up the blast furnace where they reduce the iron oxides (at different temperatures):
  Fe₂O_3(s) + 3CO_(g) 3CO_2(g) + 2Fe_(s)
  Fe₂O_3(s) + 3C_(s) 2Fe_(s)+ 3CO_(g)
• The products formed from the reactions above begin to melt and trickle down to the bottom of the blast furnace.
• The limestone also descends to the bottom of the blast furnace where it is thermally decomposed:
  CaCO_3(s) CaO_(s) + CO_2(g)
• The basic calcium oxide produced in this reaction then goes on to react with acidic impurities in the iron:
  FeS_(s) + CaO_(s) + C_(s) CaS_(s) + FeO_(s) + CO_(s)
  CaO_(s) + SiO_2(g) CaSiO_3(s)
• The CaS and CaSiO₃ become the ****, which also contains other impurities such as MgO, CaO, SiO₂and Al₂O₃. The liquid **** is le** dense than iron and so it floats on top of the molten iron at the bottom of the furnace.
• The molten iron and liquid **** are removed from the furnace through the tap holes at the base.
• The **** can be used to make bi-products such as cement. The hot gases produced are cleaned and are then burned as a fuel in the hot blast stoves that are used to preheat the air that is blown into the furnace.

The Basic Oxygen Steel making (BOS) Proce**

• In the UK, steel is made using the BOS proce**…