Rapid gas-particle flows in accelerating channels have been numerically investigated. Chaotically moving particles are represented as a mixture of granular gases possessing different granular temperatures. These granular temperatures are generated due to particle-wall collisions and collisions of particles of different sizes with each other. There are two mechanisms of granular temperature dissipation: (1) partially inelastic particle-particle collisions, (2) viscous losses of particles moving in gas. The model developed has been validated by the experimental data found in literature. The numerical analysis showed that the particulate friction leads to the significant losses of solids kinetic energy in jet mill nozzles of low productivity. (C) 2004 Elsevier B.V. All rights reserved.