Occurrence of d block elements

Ti  –    Ilmenite FeTiO_{3 ,} Rutile TiO₂
Fe –    Hematite Fe₂O_{3 ,} Magnetite Fe₃O_{4 ,} Iron pyrites FeS_{2 ,} Siderite FeCO₃
Cu –   Chalcopyrite CuFeS₂

Extraction of iron (Blast furnace method)

• Iron ore, coke (as a reducing agent) and limestone (as a slag forming substance) are used as raw materials. The amount of CaCO₃ used is dependent on the amount of silicate materials in the ore.

• Hot air is blown in at the bottom. Coke burns producing heat and CO.

C(s) + O₂(g) → CO₂(g)                            CO₂(g) + C(s) → CO(g)
• The temperature at the point where air enters is at about 2000 K and at the top is about 700 K.

• The iron(III) oxide is reduced to iron mainly by CO and some by carbon.

• The molten iron containing 3-4% dissolved carbon forms pig iron. Melting point of the pure iron is 1535 °C but the melting point of pig iron is at about 1015 °C, due to the presence of impurities.

• CaCO₃ decomposes to CaO and CO₂ gas. CaO reacts with silicate impurities and forms slag (CaSiO₃). Slag is also molten and floats on molten iron into the bottom. Slag protects iron from oxidizing by the air which is blown in the bottom.

• Pig iron contains 3-4 % of carbon and possibly other impurities such as Si, P, S and Mn.

• Following reactions are taken place in the temperature range of 700 K – 2000 K.
At low temperature (Below 1000 0C)
3Fe₂O₃(s) + CO(g) → 2Fe₃O₄(s) + CO₂(g)
Fe₃O₄(s) + CO(g) → 3FeO(s) + CO₂(g)
FeO(s) + CO(g) → Fe(l) + CO₂(g)
CaCO₃ (s) → CaO(s) + CO₂(g)

At high temperature (Above 1000 0C)
2FeO(s) + C(s) → 2Fe(l) + CO₂(g)
CO₂(g) + C(s) → 2CO(g)
CaO(s) + SiO₂(s) → CaSiO₃(slag)
CaO(s) + Al₂O₃(s) → Ca(AlO₂)₂(slag)