HPGR technology is a qualified solution for large-scale comminution circuits . The equipment's working principle is that two counter-rotating grinding rolls expose a column of material to high pressure, which is distributed across the gap between the rolls. Interparticle comminution is the HPGR specific grinding process in which material particles are crushed and ground within the compressed material bed and not by contact with the roll surface. Feed material can be smaller than the gap, which is an important distinction as compared to crushers, for example. The high pressure comminution process causes micro-cracks in the particles, which lead to the liberation of minerals and a higher portion of fines. HPGR treated minerals show better leaching performance, because the micro-cracks increase the particle contact surface for the leaching liquid. Also, flotation efficiency is further enhanced through the use of HPGR comminution.
Cost and Energy Efficiency
Grinding of material in HPGRs has proven to be more cost efficient as compared to conventional mills and crushers. Especially downstream processing stages such as ball-milling are more energy-efficient with an HPGR due to the finer product size distribution coming out and the additional effect of micro cracks within the product particles. In essence, the main motivation to use HPGR's is to save energy and production costs.
Varied uses of an HPGR
HPGRs can be employed in brownfield projects to de-bottleneck conventional crushing/milling circuits so as to increase total plant capacity. They can also be used as tertiary and/or quaternary crushing stages or in the pebble-crushing stage to improve downstream milling performance.