The perfect mixing model is calibrated to a dry grinding mill used to prepare iron powder for powder metallurgy applications. The calibration procedure was modified to account for possible error on both the mill feed and discharge size distributions, while the usual calibration criterion is based on the estimation error of the mill product size distribution. The calibration criterion was also modified to allow the simultaneous processing of several sampling campaigns to estimate common appearance, breakage and discharge rate functions. Calibration results are analysed in terms of reproducibility of model estimates and model capacity to predict the mill powder content as a function of the mill throughput and power drawn. (C) 2004 Elsevier B.V. All rights reserved.