A treated ore containing inert solids and soluble copper sulfate is to be leached in a

countercurrent multistage extractor using pure water to leach the copper sulfate. The

underflow input consists of $10,000k\frac{g}{h}$ of inert solid, $1,200k\frac{g}{h}$ of copper sulfate and $400$

$k\frac{g}{h}$ of water. The exit overflow consists of $92wt\%$ water and $8wt\%$ copper sulfate. A

total of $95\%$ of the copper sulfate is to be recovered from the inlet feed. The underflow $N$

$=0\mathrm{.}5kg$ insoluble inert solids $\frac{?}{kg}$ solution $($ hint: what does this mean for the equilibrium

curve?$).$ Calculate the number of stages required and the inlet and exit mass flowrates and

compositions of the overflow and underflow $($composition is to be reported on the basis of

the mass fraction of the soluble component$).$