Model-based procedure for scale-up of wet, overflow ball mills part III: validation and discussion

Abstract

A new ball mill scale-up procedure is developed. This procedure has been validated using seven sets of full-scale ball mil data. The largest ball mills in these data have diameters (inside liners) of 6.58m. The procedure can predict the 80% passing size of the circuit product to within ±6% of the measured value, with a precision of ±11% (one standard deviation); the re-circulating load to within ±33% of the mass-balanced value (this error margin is within the uncertainty associated with the determination of the re-circulating load); and the mill power to within ±5% of the measured value. This procedure is applicable for the design of ball mills which are preceded by autogenous (AG) mills, semi-autogenous (SAG) mills, crushers and flotation circuits.The new procedure is more precise and more accurate than Bond's method for ball mill scale-up. This procedure contains no efficiency correction which relates to the mill diameter. This suggests that, within the range of mill diameter studied, milling efficiency does not vary with mill diameter. This is in contrast with Bond's equation—Bond claimed that milling efficiency increases with mill diameter.