$10.$ A grinder is to be used $($which is $8\%$ efficient$)$ to handle $10$ tonnes per hour of a siliceous ore $($specific gravity$=2\mathrm{.}65).$ The feed and product analysis are given below :

The grinder costs Rs$.40,000.$ It operates on a $24-$hour basis for $300$ days per year and the maintenance, overhead and replacement costs amount to $50\%$ of the power costs. Electricity costs $70$p$.$ per kWh$.$ If the machine depreciates on a straight$-$line basis for $10$ years estimate the annual processing costs of the ore if the work index of the ore is $13\mathrm{.}57$ kWh$/$tonne