COMPARING ENERGY EFFICIENCY OF MULTI-PASS HIGH PRESSURE GRINDING ROLL (HPGR) CIRCUITS

摘要

With increased emphasis on reducing costs and carbon emissions in mineral processing, it isbecoming essential to employ the most efficient comminution devices and to use them to maximumeffect. High pressure grinding rolls (HPGR) are considered highly efficient compared with otherdevices, however their relative efficiency in multi-HPGR circuits is less well understood.A series of comminution tests was carried out to evaluate three multi-pass HPGR circuits and a jawcrusher-ball mill circuit. Combinations of HPGR units (1.0 m and 0.25 m diameter), jaw crushersand Bond ball mills were used to grind a 32 mm top size porphyry copper feed (BBWI = 12.1) to aproduct P_(80) size of about 150 μm. Up to three passes of HPGR were used in each circuit, with energymeasurement and size analysis at each point in the comminution process.The energy efficiencies of individual comminution stages and of the overall circuits were quantifiedand evaluated using three different approaches. The operating work index method for comparingcomminution energy efficiency underestimated HPGR performance due to the large amount of finesgenerated. The -75 μm efficiency factor and F_(50)/P_(50) reduction ratio interpolation methods both give afairer measure because they better take into account the amount of fines generated by HPGR.The results show that the relative comminution efficiencies of the three multi-pass HPGR circuitstested differ by as much as 22%, providing insights as how to best employ HPGR in a comminutioncircuit. The most energy efficient of the circuits tested was a three-pass HPGR circuit with a 1.0 mdiameter roll on the first pass in closed circuit with an 8 mm screen followed by a second and thirdpass in a 0.25 m roll.