Experimental observations of mill operation parameters on kinematic of the tumbling mill contents

Abstract

The present paper aims to investigate the key points of kinematic of contents inside the mill (load orientation), namely the shoulder, toe, impact, and pool angles. The kinematic of the mill contents in wet grinding is influenced by a range of parameters such as: media charge level (ball filling), slurry filling, and mill speed. In this work the influence of these operating parameters was investigated using a pilot mill (1000 × 500 mm). To this end, a Copper ore (-1000 μm) was used to prepare slurry at 50% solids concentration by mass. The tests covered a range of slurry filling (U) from 0 to 2.92 with ball filling 24% and 30% of mill volume and 6 different speeds between 60% and 85% of critical speed. It is observed as the mill speed increases, the more the impact angle will decrease. Toe angle increases in the range 15-25 degrees by formation of the pool in mill and exertion of the floating (buoyancy) forces to the particles inside the mill. The more the mill speed and the slurry filling increase, the more the shoulder angle will increase. The increase in slurry volume leads to the elevation of the pool level and therefore, the pool angle will exponentially decrease.