Increasing production and ensuring grinding discharging slurry particles that can meet the requirements is the ultimate goal of ball mill. In the cement industry, to achieve this goal, we should adopt closed-circuit process, namely the slurry discharging by the ball mill, sieve, and sieve material back to the ground again. In the ceramic industry, it also must be so. In the discharging place of ball mill, set up five or six sieve, materials on sieve with water is rushed back to the mill, grinding again, so that make the slurry particles meet the requirements of ball mill.

A control system and method are disclosed for controlling the operation of a ball mill grinder device operative in conjunction with a spiral ore particle size classifier operative in a closed circuit arrangement. The sum of the new ore material feed rate and the recycled ore material feed rate of the ball mill is regulated to be substantially equal to the desired maximum material flow rate capacity of the ball mill. The desired control of the ball mill is determined in relation to the motor power consumed by the spiral classifier as a function of the recycle rate integrated over the period of screen retention time, and divided by that time, to provide the effective mean value of the recycle rate. The instantaneous value of the recycle rate, for each determined iteration time, is stored in a memory table and referenced in relation to the material retention time of the spiral classifier to establish the present recycle rate going back to the ball mill from the spiral classifier.