Jan 01, 2016 · The feed size of an ore to a 1.7 m × 1.7 m wet ball mill operating in closed circuit was 5000 μm. The work index of the ore was determined under dry open circuit conditions and found to be 13.5 kWh/t. The mill bed was filled to 30% of its volume with balls of density 7.9 t/m 3. A 20:1 reduction ratio of ore was desired