The consideration that the mass discontinuities of brittle. materials statistically present fractal behavior makes available a new approach to the elucidation of crushing and grinding process. Through crushing and grinding experiments of characteristics brittle materials, the breakage distribution function (particle size distribution of products of a single breakage event) is defined as the sum of two distinct distribution (fragments and dust). The breakage distribution function follows a geometric dimensional scale and is depending on two new statistical characteristics constants of the material. Entering the number of breakage events, as the independent variable of the aforementioned function, a theoretical model of grinding process is formulated. The application of the theoretical model in any given size reduction process allows the definition of the process breakage probability distributions function and thus the theoretical model can be transformed to an actual simulation model of the process. The reliability of the new approach in describing the evolution of particle size distribution during the crushing or grinding was evaluated by its application in characteristics experimental and industrial installations. (c) 2007 Elsevier B.V. All rights reserved.