Acoustic estimation of the particle size distributions of sulphide ores ina laboratory ball mill

The acoustic signals emitted from a laboratory-scale ball mill were used fo r the estimation of the comminution of two complex sulphide ores, viz. Mere nsky and UG2 ores from the Bushveld Igneous Complex in South Africa. The di gital acoustic signals were transformed to power spectral densities that co uld be related to particle size distributions (-75 mum to 4000 mum) in the mill by use of continuum repression. This approach is more general than pri ncipal component regression methods or Kalman filtering used previously and resulted in significantly more accurate calibration in the case of the Mer ensky ore, where approximately 93.4% of the variance in the particle size d istributions could be explained. With fewer data available, the variance in the particle size distributions in the UG2 ore could be explained less acc urately (82.4%), bur still satisfactorily. In addition, smaller particle si zes (less than 300 mum) could be modelled more accurately in the case of th e UG2 ore.