Size Reduction and Material Handling

Using Rittinger's law $E = K_R \left(\frac{1}{d_2} - \frac{1}{d_1}\right)$, the energy required to crush a material from an initial feed diameter $d_1 = 20.0\text{ mm}$ to product diameter $d_2 = 5.0\text{ mm}$ is $12.0\text{ kWh/tonne}$. If the material is crushed from $d_1 = 20.0\text{ mm}$ to a finer product $d_3 = 2.0\text{ mm}$, the energy required in $\text{kWh/tonne}$ is ________ (answer in integer).