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50.9 LOCAL METHOD OF EXTRACTION OF IRON

1. Arc Method. This is the modern method used in GHANA. This method involves smelting scrap iron at a high temperature. Scrap iron is any discarded iron material. The high temperature is provided by an electric arc produced when a pair of high voltage oppositely charged electrodes are brought near each other.

2. In a typical local production of iron, a mixture of iron ore, oyster shells and charcoal or palm kernel shells is loaded into a kiln or furnace. Fire is then set at the bottom of the

furnace. Bellows are used to blow air continuously through the lower parts of the furnace.

The charcoal burns to produce CO2.

C(s) + O2(g) CO2(g)

As the CO2 rises up the heap in the furnace, it reacts with more charcoal to produce carbon (II) oxide, CO.

CO2(g) + C(s) → 2CO(g)

CO reduces iron ore, either FeO or Fe2O3, to iron metal.

FeO(s) + CO(g) Fe(l) + CO2(g)
Fe2O3(s)
+ 3CO(g) → 2Fe(l) + 3CO2 (g)

The oyster shells contain limestone which is a source of CaCO3. When heated, CaCO3 decomposes producing calcium oxide and CO2.

CaCO3(s) → CaO(s) + CO2(g)

The calcium oxide combines with silica (SiO2) removing this impurity in the form of slag.

CaO(s) + SiO2 (s) → CaSiO3(s)

Calcium trioxosilicate (lV)

The molten iron flows to the bottom of the furnace where it is collected.