Lifters/liners worn in tumbling mill and consequently their dimensions change during the course of operation. These changes in dimensions have a significant influence on the overall economic performance of the mills. In this project, the influences of slurry filling and slurry concentration on the wear of lifters were investigated using a pilot mill of 1m diameter and 0.5m length. Copper ore with a size smaller than one inch was used to prepare slurry at 40%, 50%, 60%, 70%, and 80% solids concentration of mass. The tests covered a range of slurry filling from 0.5 to 2.5 with ball filling at 20% and mill speeds at 75%. The mill grinding mechanism in this pilot mill is a combination of both impact and abrasion mechanisms. It was found that the lifters’ wear rises with the increase of feed filling in the mill under dry conditions. During the wet condition, when there is an increase in the slurry filling and slurry concentration, the wear decreases. In wet grinding, the relative velocity between the materials and the lifters is more than in the dry mode and the wear is 1.5–3 times greater than in the dry condition.