In this paper we present a generalization of the asymptotic solution of the batch grinding equation proposed by Kapur in 1970. It is shown how this can be combined with the residence time distribution to give the particle size distribution of the product of a continuous grinding process. The residence time distribution in a stirred bead mill has been determined by tracer experiments and used to propose a flow model of the mill. The results of batch grinding experiments of hydragillite are combined with this flow model to successfully predict the product size distribution in continuous grinding experiments.