Which of the following process is related with the removal of sulphur by heating in the air ?

Options

A. Smelting
B. Calcination
C. Annealing
D. Roasting

Answer

4

Explanation

Roasting is the process of heating the ore strongly in the presence of excess of air. The process is usually carried for sulphide ore and the following changes take place.
`(i)` Moisture is removed.
`(ii)` The voltatile impurities are removed.
`(iii)` Impurities of sulphur, arsenic, phosphorus etc. are removed in form of volatile oxide.
`S+O_(2)rarrSO_(2)uarr," "4As+3O_(2)rarr2As_(2)O_(3)uarr," "P_(4)+5O_(2)rarr2P_(2)O_(5)uarr`
`(iv)` Sulphide ores get oxidised in to metal oxides
`2FeS+3O_(2)rarrFeO+2SO_(2)`