Effects of mixtures of grinding media of different shapes on milling kinetics

Mixtures of grinding media of different shapes have different surface areas and contact mechanisms in grinding action, due to differences in their geometry. They can consequently increase the breakage rate in a particular milling environment. [Display omitted] •Spherical balls are the most efficient grinding media shape.•Alternative shapes can reduce grinding costs and increase milling efficiency.•Due to their geometry, these grinding media can increase the milling kinetics.•An optimal mixture made of different shapes can be used alternatively to balls. The effect of grinding media on milling kinetics has been generally studied using one media shape. However, very little work has been done on investigating mixtures of media shapes. Combining different grinding mechanisms in term of contacts, the volume of grinding zones can be efficiently increased when there is an optimal mixture of two or more grinding media with different shapes and, therefore the milling kinetics will be improved. A series of batch grinding tests was carried out using the same mass of spherical balls, Eclipsoids™ and cubes to break coarse, medium and fine sizes of quartz material. Then, mixtures of the same mass made of spherical balls and cubes, spherical balls and Eclipsoids™ were successively considered. The breakage parameters were determined and used to evaluate the grinding performances of the mixtures of grinding media under the same conditions. It was found that mixtures of grinding media shapes can increase the breakage rate in a particular milling environment. But, spherical balls remain the most efficient grinding media. Finally, an optimal mixture made of spherical balls and grinding media of different shapes, namely cubes and Eclipsoids that are cheaper to manufacture can be used in the grinding process alternatively to 100% balls.