The energy required per unit mass to grind limestone particles of very large size to 100 μm is 12.7 kWh/ton. An estimate (using Bond's law) of the energy to grind the particles from a very large size to 50 μrn is

• 6.35 kWh/ton
• 9.0 kWh/ton
• 18 kWh/ton
• 25.4 kWh/ton