Optimization consists in a bound minimization of refining time using the desirability function. Before experiments, working conditions were 70 rpm for as and 55 min for rt. The optimum conditions calculated by optimization were as follows: 58 rpm for as and 38.5 min for rt. The new working conditions identified for the ball mill considered enabled to rise output from 109 kg/h to 156 kg/h, with a 43% increase in