A mass balance is being made for a proposed carbothermic reduction process for the

zinc calcine. Enough carbon $($in the form of graphite, pure C$)$ will be added to reduce

all the lead, zinc oxide and sulphate in the calcine to metallic lead and zinc vapour, and

to reduce all the hematite to FeO. The sulphur will leave the system as $S{O}_2$ and it is

assumed that all the carbon will wind up as $CO$ in the off$-$gas. What is the

stoichiometrically required mass of graphite?

$480$ T per day Zinc calcine

$717$