Industrial investigation of the effect of hydraulic pressure on HPGR performance

During the last decade, the application of HPGR in mineral processing has been on the rise as energy-efficient grinding equipment. This industrial-scale study investigated the effect of hydraulic pressure on operational performance, product size distribution, and energy consumption. The results demonstrated that increasing the pressure from 140 to 180 bar reduced the product P80 by 23%, while the fraction of particles finer than 8 mm increased from 58.7% to 62.3%. The optimum reduction ratio closely corresponded to the 8 mm screen aperture, confirming HPGR effectiveness near this critical size. Although power consumption increased by 24%, from 636 to 790 kWh, Bond Work Index calculations showed that producing a target P80 of 120 μm required total grinding energies of 10.22, 10.77, and 12.13 kWh/t at 180, 160, and 140 bar, respectively, demonstrating an energy advantage at higher pressures. Despite consuming an additional 0.31 kWh/t relative to fresh feed, HPGR reduced downstream grinding requirements by up to 2.1 kWh/t. The Bond Ball Mill Work Index also decreased by 16%, from 16.13 to 13.49 kWh/t. Narrowing the roll gap from 52.5 to 48 mm and reducing speed from 475 to 455 rpm enhanced microcracking and residence time, potentially improving breakage efficiency and throughput.