The application of High Pressure Grinding Rolls (HPGR) in the mining industry, especially as a replacement for the conventional Semiautogenous (SAG) milling process, is receiving a great deal of interest with many our mining clients considering the use of this process to reduce energy consumption and costs.

The HPGR technology has been in existence for many years. It was originally developed and applied in the cement industry and was introduced into the mining industry in the early 1980s for the crushing of kimberlite ore in diamond mines. The application and advantages of using these grinding rolls to extract diamonds is now well established. HPGR technology was also successfully introduced and applied in the iron ore and limestone industries and is now making in-roads into hard rock mining applications.

The Process

High Pressure Grinding Rolls consists of a pair of counter rotating rolls, one fixed and the other floating. The feed is introduced to the gap in between the rolls and is crushed by the mechanism of inter-particle breakage. The grinding force applied to the crushing zone is controlled by a hydro-pneumatic spring on the floating roll. Speeds of the rolls are also adjustable to obtain optimum grinding conditions.