Testing method for ball mills

1. A testing method for designing a semiautogenous or an autogenous grinding circuit having at least one ball mill for grinding ore, the method comprising:

measuring an amount of time for grinding a predetermined mass of ore to a first predetermined size, in a first, semiautogenous step;

calculating a required grinding energy based on the measured time for grinding in the first step, mass of ore, mill characteristics and a measured specific gravity;

grinding in a ball mill, in a second step, the ore from the first step to a second predetermined size; and

calculating, using the Bond Mill Work Index, a required ball mill energy for the second step required to obtain a desired final grind size.