A review of the effects of grinding media and chemical conditions on the flotation of pyrite in refractory gold operations

• The influence of grinding environment on pyrite floatability was reviewed.
• Galvanic interactions affect pyrite floatability.
• Ore mineralogy, grinding media and added reagents influence pyrite surface.
• The effect of added reagents during grinding is a less researched area.

Flotation performance of gold-bearing pyrite in refractory gold ores depend upon the interplay among process water chemistry, grinding chemistry, and ore mineralogy. The nature of pyrite itself (finely disseminated reactive pyrite vs. low reactivity) also plays a role in its surface reactivity. This paper reviews the experimental studies examining the interactions between grinding media, gold bearing pyrites and process water occurring during grinding of refractory gold ores and the effect of these interactions on flotation response of pyrite. The literature review reveals that the interactions are highly convoluted. It appears that the galvanic interactions between forged steel media and sulfide minerals ores are particularly significant after grinding of massive sulfide ores. Process water chemistry can also have an amplifying effect, as the process water becomes more laden with cyanide species and other ionic species. This paper should contribute an improved understanding of electrochemical and chemical processes occurring during the grinding of refractory gold ores, which is essential to improve flotation performance of pyrite. Judgement is reserved with regards to the overall economics associated with the use of various grinding media. Media consumption due to wear will have to be balanced against flotation recovery of gold bearing sulfides and whole circuit behaviour where gold in tailing may also be further recovered through leach processes.