Size Reduction and Milling

Bond's law gives $E = 10 W_i \left(\frac{1}{\sqrt{P}} - \frac{1}{\sqrt{F}}\right)$. For feed size $F = 1600\text{ \mu m}$ ($\sqrt{F} = 40$) and product size $P = 400\text{ \mu m}$ ($\sqrt{P} = 20$), with $W_i = 12\text{ kWh/tonne}$, energy $E = 10(12)(1/20 - 1/40) = 120 (0.05 - 0.025) = 120 \times 0.025$ in kWh/tonne is: