The components of a comminution plant include a ball mill, a discharge sump, and a hydrocyclone

classifier. Three sizes $($class $1,2$ and $3)$ of dry ore are fed to the plant at a rate of $175$ tonnes per

hour in the following respective ratios $5$:$3$:$1.$

To ensure that the slurry density within the mill is $75\%$ solids, water is added to the mill feed.

Additionally, there is an additional point to add more water at the discharge sump where the slurry

is pumped to the hydrocyclone. The Hydrocyclone feed's density is set at $55\%$ solids.

The hydrocyclone performance is such that $80\%$ of class $1,40\%$ of class $2,15\%$ of class $3,$ and

$10\%$ of the water entering the cyclone reports to the oversize stream.

The selection and breakage function approach may be used to model the milling process, where $Si=$ a$($di$)\backslash$beta $($hr$-),$ where a and $$ are given as $0\mathrm{.}65$ and $0\mathrm{.}42,$ respectively. The three size classes are:

class $1(+900m),$ Class $2(-900+600m)$ and class $3(-600m).$ Lower screen size is used for

size reference purposes.

The breakage function b$21$ is given as $0\mathrm{.}36.$

You are required to:

$1.$ Create a flowsheet diagram that is fully annotated

$2.$ Calculate the minimum mass of ore required in the mill to ensure that the percentage of class $1$

in the circuit product is at least $7\%,$ assuming a perfectly mixed mill.

$3.$ While the circuit remain the same, the ore becomes harder and now parameters a and $$ change

to $0\mathrm{.}69$ and $0\mathrm{.}40.$ Describe any changes you see while simulating these changes.

$4.$ Suggest some corrective action that you may need to take to ensure that the circuit allows no

more than $7\%$ class $1$ in the product stream.

$5.$ Construct a table showing flowrates in dry tonnes per hour of ore, composition of the three

classes, and water tph for four streams that you consider most important.