Modelling of cohesive granular flow in powder processing

Several polymer processing operations such as rotational moulding and powder coating involve avalanching flow of granular materials. The objective of this work is to develop a model and simulate mixing and segregation of granular particles during such flow. The movement of particles has been modelled using the Monte Carlo approach. Important forces such as interparticle friction, adhesion and electrostatic forces have been incorporated in the simulation. Simulation results show segregation in the bed as a result of size differences and are consistent with published results for cohesionless systems. The simulation allows for the quantitative evaluation of the effects of particle characteristics and material properties on the flow behaviour of granular materials during processing, which, otherwise, could not easily be determined experimentally. Results showed that the gradual development of cohesive forces inhibits the movement of particles and can lead to the development of reverse segregation patterns.