Pushing the Use of High Pressure Grinding Rolls in Magnetite Circuits

摘要

HPGR technology has been used at a number of magnetite mines in the world and have significantrnenergy advantages over SAG and AG technologies. The early design at Los Colorados in Chile hasrnbeen in operation for more than 12 years – and operates very successfully though only reduces thernfeed size to -5mmrnThe Whyalla project magnet design pushed the concept to produce a preconcentrate of 80%-rn350micron – a significant reduction on previous plants though with some wear problems in the earlyrnyears. The Karara design backpedalled slightly and will only crush to 80%-1.8mm.rnHowever, the design issues of using a HPGR to further reduce the feed size continue to be explored.rnThe aim is to reduce the process risks associated with wear and also to reduce the complexity of therndownstream process – with consequent benefits in terms of capital and operating costs.rnThe designs are being developed for a couple of projects – one planned to produce 20Mtpa ofrnconcentrate with the potential to not only remove SAG and AG milling but also ball milling. Thernconcept is to use multiple passing through the HPGR since, on the data available, the efficiency of thernHPGR to reduce size does not significantly diminish as the feed size is reduce. This can be havernbenefits in both capital and operating cost.