This study investigates the parameters affecting the grinding process in a tumbling wet ball mill to produce a highly loaded, finely ground slurry with good rheological properties and good stability. The independent factors selected were solids, amount of dispersant and grind time. Experiments were conducted by choosing independent factor levels corresponding to a central composite design. The responses measured were % < 22 mum, apparent viscosity at 200/s and % stability. The % < 22 mum and apparent viscosity response data were fit to the independent factors with a second-order model. Contour plots were drawn to better understand the effect of solids, dispersant [ammonium lignosulfonate (ALS)] and grind time on the particle size reduction and slurry rheology. It was observed that excess amounts of ALS may cause hard packing. ALS was found to aid particle size reduction only at higher grind times.