balance and  balance give weight of roasted product .

Roasted ore contains and .

Amount of  and  can be determined from their percentages in roast product, these are and  respectively.

All  in roasted ore is present as , therefore amount of .
It is not known in what form Fe is present in the roasted product. Problem says is present as and . It is important to perform S balance.

Sulphur in roasted .

S in .

From the amount of  we can find S in  and we can obtain S in  which is equal to
Amount of

Let  and  in roasted ore.

oxidized to  and .

in roasted ore is either with  or .

Performing  balance and oxygen balance





and .

Proximate analysis of roast product is