What is produced when zinc blende is roasted in air?

Explain Calcination and Roasting in detail.

The main function of roasting is

Choose the correct code regarding the Roasting process.
$I$. It is the process of heating ore in air to obtain the oxide.
$II$. It is an exothermic process.
$III$. It is used for hydrated oxide and oxysalt ore.
$IV$. It is used after the concentration of ore.

The major products of the following reaction,$2ZnS_{(s)} + 3O_{2(g)} \xrightarrow{\text{Heat}} \dots$ are

$A$ reverberatory furnace is employed in the metallurgical process mainly for