Success Story - Case Study: Improving copper recovery by changing the grinding chemistry


A comprehensive series of laboratory tests, commencing in 2004, consistently showcased the benefits of transitioning from forged steel to high chrome grinding media. This shift not only led to a transition towards more oxidizing Eh values and an increase in dissolved oxygen but also resulted in a reduction in EDTA extractable iron. Copper recoveries significantly improved, prompting the decision to proceed with a pilot plant study. Subsequently, additional test work was conducted on various ore types to further enhance confidence levels before undertaking a comprehensive full-scale plant trial.


We completed a pilot plant in April 2008 to increase confidence in the laboratory results and reduce the risk involved in moving to a full plant trial. A plant trial with high chrome media in the ball mill was conducted in late 2009. Due to the plant treating a variety of ore types during the trial, the analysis was split into three sections: high grade, intermediate grade, and low grade ore.


Overall, results showed that grinding with high chrome grinding media:

  • Reduced the wear rate by 30%.
  • Changed the pulp chemistry by increasing both the Eh and dissolved oxygen; and reducing the EDTA extractable iron by more than 80%.
  • Increased copper recovery by 2.0±0.7 percent, and copper grade by 0.7±0.4 percent.