Question $3$

$(40$ marks$)$

A$.$ A PbS concentrate is produced by a rougher$-$cleaner flotation circuit. The cleaner tailings

assay $15\%PbS$ are recycled to the rougher cells, and the circulating load $($recycle$/$fresh

feed$)$ is $0\mathrm{.}3.$ The fresh feed assays $10\%PbS$ and is delivered at the rate of $1000$ tons $\frac{?}{hr}.$

The recovery $(PbS$ in cleaner concentrate $\frac{?}{PbS}$ in fresh feed$)$ and grade in the concentrate

are $95\%$ and $85\%$ respectively. What are the flow rates and assays of the other streams?

$(15$ marks$)$

B$.$ A lead zinc mill treats $150$ tons$/$day of ore assaying $8\%Pb$ and $12\%Zn$ and produced a

lead concentrate of grade $75\%Pb,4\%Zn$ and zinc concentrate of $55\%Zn,1\%Pb.$ The

tailing assay is $0\mathrm{.}4\%Pb$ and $0\mathrm{.}8\%Zn.$ How much $Pb$ and $Zn$ concentrates are produced in

the plant per day. $[15\mathrm{.}04$ tons$/$day$,30\mathrm{.}11$ tons$/.$

$(15$ marks$)$

C$.$ Calculate how many $kg$ of magnetite must be added to $1L$ of water to make a

slurry with a pulp density of $1\mathrm{.}9\frac{g}{c}{m}^3.$ Assume density of magnetite is $5\mathrm{.}2\frac{g}{c}{m}^3$

$(10$ marks$)$

Answer all questions please