Effect of galvanic interaction between grinding media and minerals on sphalerite flotation

The effect of galvanic interaction between grinding media and minerals on sphalerite flotation is discussed. The effect of the presence and absence of oxygen as well as the activator and the collector during galvanic contact on the flotation recovery of sphalerite was also studied. X-ray photoelectron spectroscopy (ESCA) studies were used to identify the reaction products on the sphalerite surface after galvanic interaction with the grinding media under different experimental conditions. Prior galvanic interaction of sphalerite with the grinding media was found to lower its floatability significantly, especially if oxygen was present during the contact. The deleterious effect of such a galvanic interaction on sphalerite flotation could be minimized if sufficient concentrations of copper sulphate could be added during contact or still to a greater extent if higher than the optimum concentration of activator is used while conditioning the galvanically interacting sphalerite sample. Surface analysis studies indicate that the above observed decrease in sphalerite floatability owing to prior galvanic interaction is mainly due to the presence of oxy-hydroxide species of iron on the mineral brought about by the anodic dissolution of iron from the grinding media.