Modeling Of Grinding Kinetics At The Sidbec -Normines Port -Cartier Pelletizing Plant

Sidbec-Normines operates six large iron ore concentrate regrinding mills in parallel and open circuit at its Port-Cartier pelletizing plant. Grinding kinetics in these mills were characterized for slurry densities varying between 70 and 89% solids, using a lumped parameter size discrete model. Optimum grinding conditions were encountered at 83.5 to 84% solids. Higher densities decreased the normalized selection function and increased slurry short-circuiting, yielding a sharply coarser mill discharge. At lower slurry densities, the normalized selection function decreased and the mill discharge coarsened slightly. The grinding kinetic model predicted particle size distributions within the mill. These were found to vary significantly from the feed to the discharge end. This is likely to cause nonlinear breakage kinetics.