Roasting is a process of oxidizing zinc sulfide concentrates at high temperatures into an impure zinc oxide, called "Zinc Calcine". The chemical reactions taking place during the process are:

{\displaystyle {\ce {2ZnS + 3O2 -> 2ZnO + 2SO2}}}{\displaystyle {\ce {2SO2 + O2 -> 2SO3}}}

Approximately 90% of zinc in concentrates are oxidized to zinc oxide. However, at the roasting temperatures around 10% of the zinc reacts with the iron impurities of the zinc sulfide concentrates to formzinc ferrite. A byproduct of roasting issulfur dioxide, which is further processed intosulfuric acid, acommodity.[2]The linked refinery flow sheet shows a schematic of Noranda's eastern Canadian zinc roasting operation[5]

The process of roasting varies based on the type of roaster used. There are three types of roasters: multiple-hearth, suspension, and fluidized-bed

The roasting is the process of burning of a ore in the presence of the excess air.so, the zinc sulphide will be heated with excess of the air....the follwing reaction will be performed.....2ZnS + 3O₂→2ZnO + 2SO₂.

Whereas,the calcination is the process of heating of a ore in the absence of the oxygen,so this will perform the following reaction.....ZnCo₃→ZnO+CO.......

by roasting process its a best mehthod

Metals such as iron, zinc, lead, copper, etc., are in the middle of the reactivity series. These are moderately reactive metals and are usually present as sulphides or carbonates.

A metal is obtained from its ore by the processes of reduction or by electrolysis. In the reduction process, it is the oxide ore that is reduced.

It is easier to reduce an oxide ore as compared to its sulphides and carbonates. If the ore is not an oxide ore, it is first converted to the oxide by the process of calcination or by roasting.

Roasting

Sulphide ores are converted into oxides by heating strongly in the presence of excess air, so that oxygen gets added to form the corresponding oxides. Sulphur impurities escape as gas. This process is known as roasting.

1.)the roasting is the process of burning of a ore in the presence of the excess air.so, the zinc sulphide will be heated with excess of the air....the follwing reaction will be performed.....2ZnS + 3O₂→2ZnO + 2SO₂.2.)whereas,the calcination is the process of heating of a ore in the absence of the oxygen,so this will perform the following reaction.....ZnCo₃→ZnO+CO.......I hope my answer will be helpful to u in future also.....so,if u find it helpful....plz mark it as a brainlist answer.......