Define 'mixing' and list seven uses of mixing.

QUESTION $2$

$($a$)$ A rake classifier is operating at a cut size of $30$ mesh, United States standard sieve series. The specific gravity of the particles is $1\mathrm{.}5.$ The fluid used is water at $25C.$

Calculate the settling velocity of the particles whose size corresponds to the cut size.

Use the following given data:

Cut size $=30$ mesh

Specific gravity $=1\mathrm{.}5$

Water $($fluid$)=25C,$ temperature

Apertures width in $30$ mesh sieve is $589$

$D=589=0\mathrm{.}000589=5\mathrm{.}89{10}^{-4}$

Settling Velocity $=?$ Size corresponds to cut size

$V_2=(P_p-p)g^{**}D\frac{2}{18}$

$R_e=DV\frac{P}{}$

$($b$)$ Slab material $0\mathrm{.}9m$ long, $0\mathrm{.}3m$ wide and $2\mathrm{.}5cm$ thick is to be dried to a $20\%$ moisture content, dry basis. Only one side of the slab is exposed to the drying medium. The original material contained $0\mathrm{.}75kg$ of water for every $1kg$ of dry solid. The equilibrium moisture content is $0\mathrm{.}7\%$ dry basis. The critical moisture content is $55\%$ dry basis. The dry density of the material is $512kg$ per cubic metre, the rate of drying at the critical moisture content is $2kg.m^2$ per hour.

Use the following formula: $L=$ WdS $100$ to determine:

the initial moisture $($Li$)$

the final moisture $($Lf$)$

$(10)$

the critical moisture $($LC$)$ for this material