### Grinding & Rheology of Dense Coal Water & Mineral Water ...

The laboratory mill used was 200 mm i.d. with a volume of 5800 cm³, fitted with lifters. The ball charge was 140 one-inch diameter balls with a bulk volume of 2290 cm³ (40% loading) and a void volume of 870 cm³ (38%). All tests were run at 60 r.p.m. with a constant slurry volume loading of approximately 700 cm³.