Effect of slurry pool formation on the load orientation, power draw, and impact force in tumbling mills

• Investigate the effects of mill speed, slurry concentration and slurry filling on the impact forces.
• The influences of the slurry pool formation on the mill power draw were investigated.
• Study load behavior and slurry pool in a 1 m × 0.5 m pilot mill
• A quartz load cell (ergometer) was installed on the mill shell used in order to measure impact forces and impact angles.

The present paper aims to investigate: 1) the impact forces in terms of variables like: mill speed, slurry concentration, and slurry filling; 2) the key points of load orientation, namely the shoulder, toe, impact, and pool angle in wet grinding; and 3) the influences of the slurry pool formation on the mill power draw. In this work the influence of these operating parameters were investigated using a pilot mill (1000 ∗ 500 mm). To this end, a Copper ore (− 1000 μm) was used to prepare slurry at 50% solid concentration by mass. The tests covered a range of slurry filling (U) from 0 to 2.5 with ball filling 30% of mill volume and 6 different speeds between 60% and 85% of critical speed. It is observed as the mill speed increases, the shoulder angle will increase and the impact angle will decrease. By formation of the pool and exertion of the floating (buoyancy) forces to the particles inside the mill, the toe angle increases 15–25°. The results delineate that the increase in the mill speed leads to a remarkable increase in the magnitude and frequency of the impact forces. An increase in slurry filling and the resulting formation of the pool, the impact forces will decrease. It is found that with the increase in slurry concentration, the slurry will act as a damper decreasing the impact forces. Results show that there are a definite trend between the power draw and the slurry filling.

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