Experimental and Numerical Investigation of the Energy Utilisation in a New Vertical Roller Mill

Comminution is an energy-intensive stage in the overall manufacturing process to provide materials to a required final product property specification. The development and application of new comminution systems has always been driven by the inefficiency of conventional comminution devices, such as tumbling ball mills. A new vertical roller mill has recently been developed by International Innovative Technologies, IIT Ltd. It is used in this work to evaluate its energy utilisation for materials with differing grindability. The mill comprises six rollers – rotating at up to 2000 rpm – mounted vertically on swing arms hinged to a central shaft which rotates at up to 450 rpm. The rollers crush particles against a grinding ring mounted in the mill wall. The coarse feed enters the top of the mill module via a spreader plate, propelling the material centrifugally into the grinding zone between the rollers and ring. Single particle mechanical property measurements and bulk crushing tests are used to benchmark which materials are suitable for size reduction in this mill. A systematic study for evaluating energy utilisation during comminution is reported for a range of mill variables i.e. RPM, feed rate, grinding module arrangement (single pass and multi-pass ‘Tandem’ modules in series) as a function of material physical and mechanical properties.