$3\mathrm{.}12$

$($a$)$ Using the batch flux plot data given in Table $3$E$12\mathrm{.}1,$ graphically determine the

limiting feed concentration for a thickener of area $300m^3$ handling a feed rate of

$0\mathrm{.}03\frac{m^3}{s}$ and with an underflow rate of $0\mathrm{.}015\frac{m^3}{s}.$ Determine the underflow

concentration and overflow concentration under these conditions. Sketch a possible

concentration profile in the thickener clearly indicating the positions of the overflow

launder, the feed well and the point of underflow withdrawal $($neglect the conical base

of the thickener$).$

$($b$)$ Under the same flow conditions as above, the concentration in the feed increases to

$110\%$ of the limiting value. Estimate the solids concentration in the overflow, in the

underflow, in the section of the thickener above the feed well and in the section

below the feed well.

Table $3$E$12\mathrm{.}1$ Batch flux test data