Potential control in the flotation of sulphide minerals and precious metals

In this work a method based on the use of flotation gases (air, nitrogen, etc.) is presented for potential controlled flotation. Examples of the flotation of a complex sulphide ore, and two gold ores are presented. With this control method, the potential could be kept constant within 2 to 5 mV throughout the flotation stage. The selectivity in the flotation of copper minerals from the complex ore was significantly improved under conditions of controlled potential compared to open potential conditions. At low potentials the recovery of sulphide minerals was very low whereas at high potentials created by excessive aeration the selectivity was poor. The maximum selectivity was achieved at about 0 mV vs. SHE. In the flotation of gold ores, the recovery of iron and arsenic minerals such as pyrite and arsenopyrite could be minimized by using potential control. The optimum potential for gold flotation was +250 to +300 mV vs. SHE.