High Pressure Grinding Roller(HPGR) Success Stories

In October 2004, a pilot-plant unit was commissioned in the Potgietersrust platinum mine. This was a further step forward and the first approach of HPGR technology to the platinum industry. The HPGR was again operated in closed circuit with 8-mm screens.

The feed material was prepared by two-stage crushing. Feed size was initially –25 mm but was increased to –35 mm for extended operating periods. The HPGR treated a total of 188,000 tph, resulting in 115,000 tph of final product until it was decommissioned in April 2005. The operating time was in excess of 3,000 hours.

The ore was even tougher than that used in the previous application, which is reflected in the Bond Work Index (BWI) of 22 kWh/t, and in the operational problems experienced at the crushers. The HPGR was equipped with the latest wear protection. Results from abrasion testing indicated low abrasion, which was confirmed in the field. Availabilities as high as 97% were achieved. The test installation was declared a success by the operator who, in his words, “had tried very hard to break the machine.”