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particle damage and exposure analysis in hpgr crushing of selected copper ores for column leaching - sciencedirect

particle damage and exposure analysis in hpgr crushing of selected copper ores for column leaching - sciencedirect

In mining operations, jaw and gyratory crushers are generally used for primary crushing, and cone crushers are used for secondary crushing. During the past decade, however, high-pressure grinding rolls (HPGR) are being considered due to potential processing benefits such as energy savings, improved exposure/liberation and particle weakening. At this time there is no detailed quantification of particle damage and downstream benefits from HPGR crushing are uncertain. In the present research, copper ores (copper oxide ore and copper sulfide ore) were crushed by a jaw crusher and by HPGR and the products were evaluated for particle damage and copper grain exposure by X-ray computed tomography. Column leaching was done to determine the rate and extent of copper recovery.

X-ray computed tomography analysis and laboratory column leaching experiments for copper oxide ore revealed that products from HPGR crushing have more particle damage and higher copper recoveries when compared with products of the same size class from jaw crusher crushing. Generally the copper recovery from column leaching of the oxide ore was found to be dependent on the extent of grain exposure, which increases with a decrease in particle size.

In the case of the copper sulfide ore, copper recovery was found to be independent of the crushing technique despite the fact that more particle damage was observed in products from HPGR crushing. This unexpected behavior for the copper sulfide ore might be due to the high head grade and strong leach solution. Column leaching results also show that about 8090% of the copper was recovered from the copper sulfide ore in a relatively short leaching time irrespective of crushing technique. As expected, copper recoveries improved with a decrease in the particle size of the copper sulfide ore as exposure of copper mineral grains increased.

Important features in particle damage and exposure analysis in HPGR crushing of copper oxide ores for column leaching. (a) Sections from 3D X-ray computed tomography scans for copper oxide ore samples. (b) Particle damage for copper oxide samples. (c) Photograph of the laboratory column leaching experiments. (d) Average copper recoveries from copper oxide ore samples for different crushing methods and particle sizes.Download : Download full-size image

Copper ores (copper oxide ore and copper sulfide ore) were crushed by a jaw crusher and by HPGR. Crushed and sized products were evaluated for particle damage and copper grain exposure by X-ray computed tomography. Column leaching was done to determine the rate and extent of copper recovery. HPGR crushed products have more particle damage and higher copper recoveries. Copper recovery from the copper oxide ore was found to be dependent on the grain exposure.

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