ABSTRACT

Ouchterlony (2005) introduced a different curve to model the shape of the fragmentation distribution. He called it the Swebrec function. It fits a wide range of measured fragmentation data and, in particular, fits the fines region data well when the coarser size fractions are fitted. Ouchterlony (2005) proposes an analogous model to the KuzRam model whereby the Rosin-Rammler curve is replaced by the Swebrec function and the Kuznetsov (1973) estimate is used again for the mean size estimate. Unfortunately, Ouchterlony (2005) and Ouchterlony and Moser (2006) confuse the mean and the median values for a distribution. Spathis (2004) identified such a discrepancy in connection with the original Kuz-Ram model, and indicated that others in blasting had also made that mistake. The essential point is that the Kuznetsov (1973) expression is for the mean size and not the median size. These are only identical, in general, when the distribution is symmetric.