For newly installed or overhauled grinding mills, a trial run must be conducted before putting them into production. The trial run of a grinding mill generally consists of three stages:

(1) Preparation before trial run. This mainly involves checking the motor and electrical components, the tightness of all screws; checking the integrity of lubrication and sealing measures, and performing a rotation test; checking for any abnormal phenomena.

(2) No-load trial run. After a rotation test without any abnormal phenomena, the mill can be started under no-load (without media or material) and run continuously for 8–16 hours. The following requirements should be met: normal lubrication without oil leakage; main bearing temperature not exceeding 50℃; smooth operation without abnormal noise; and no loosening of any components.

(3) Load trial run, conducted in two stages. 1) Half-load trial run: media filling rate φ = 25%–30%, feed an appropriate amount of material and water (discontinuously) and run for 8–10 hours. 2) Full-load test run: After the half-load test run checks that everything is normal, add enough medium, increase the ore quantity appropriately, and run at full load for 10-20 hours. Finally, the following requirements should be met: smooth operation without abnormal noise; main motor current fluctuates within the allowable range; temperature is below the allowable temperature rise; lubrication of all parts is normal; main bearing temperature does not exceed 60℃; and there is no leakage of ore, water, or oil in any part.