HPGR High Pressure Grinding Rolls· HPGR test results published by Grier 1992 on gold ores from the Mt Todd project showed significant energy savings for a HPGR/Ball Mill circuit as compared to a SAG/Ball Mill plant By adding a Polycom high pressure grinding roll the throughput of existing plants can be increased by as much as 150% while simultaneously reducing the power consumption by up to 20%