Ernest Henry Mining (EHM) is a copper, gold and magnetite mining and processing operation located 38 kilometres north east of Cloncurry in the Mount Isa – Cloncurry mineral district of north west Queensland, Australia. The EHM ore body is an iron oxide copper gold deposit with an average grade of 1.1 percent copper, 0.5 g/tonne gold and 22 percent magnetite.
At the end of 2009, after a series of promising laboratory test work, EHM converted the ball mill media charge from forged steel to high chrome media. Laboratory test work also indicated that with the use of high chrome media, the pH was able to be reduced with no negative impact on plant performance. At high pH values (above 10.5), the forged media is passivated, so as the pH of the system drops the media corrosion rate increases and floods the system with corrosion products,
affecting flotation. As the high chrome media is much more inert, pH has less of an effect on copper flotation response.
B. Kirkwood, J. Kinal, J. Siliezar and H. Sofatzis.