CBSE - VI - Chemistry
what are the different steps involved in extraction of metals from
haemetite and cinnabar ore ?
- 1. Concentration by gravity separation
The powdered ore is washed with a stream of water. As a result, the lighter sand particles and other impurities are washed away and heavier ore particles settle down.
- 2. Roasting and calcination
The concentrated ore is strongly heated in a limited supply of air in a reverberatory furnace. As a result, moisture is driven out and sulphur, arsenic and phosphorus impurities are oxidised off.
- 3. Smelting (in a blast furnace)
The charge consisting of roasted ore, coke and limestone in the ratio 8:4:1 is smelted in a blast furnace by introducing it through the cup and cone arrangement at the top.
i. Lower region (combustion zone) - Temperature is at 1500°C.
- i. Middle region (fusion zone) - Temperature prevails at 1000°C.
- i. Upper region (reduction zone) - Temperature prevails at 400°C.
The iron thus formed is called pig iron. It is remelted and cast into different moulds. This iron is called cast iron.
Rate this answer
You have rated this answer /10