Question
Answer the following question:
What is the difference between calcination and roasting?
What is the difference between calcination and roasting?
✓
Answer
| Calcination | Roasting |
| The ore is heated in the absence of air. | The ore is heated in excess of air. |
| Moisture and organic impurities are removed and the ore becomes porous and more reactive. | Volatile impurities are removed as oxides$\left( SO _2, P _2 O _5, A s_2 O _3\right)$ and the ore becomes porous and more reactive. |
| Carbonate and hydrated ores are calcined and$CO _2$or water vapour is given off. | Sulphide ores are roasted, so$SO _2$is given off. |
| $ZnCo _3 \longrightarrow ZnO + CO _2$ | $2 ZnS +3 O _2 \stackrel{800^{\circ}-900^{\circ} C }{\longrightarrow} 2 ZnO +2 SO _2$ |
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