LEAD ACTIVATION OF SPHALERITE DURING GALENA FLOTATION

Kinetic studies on the flotation of a fine-grained complex lead-zinc o re showed that sphalerite exhibits considerable floatability during th e later stages of galena flotation, causing a loss of zinc to lead con centrate. The lead concentrates obtained toward the end of the second lead rougher flotation were examined by X-ray photoelectron spectrosco py (XPS). The results showed that the lead-to-zinc atomic ratios on th e surface are significantly higher than in the bulk, suggesting that t he flotation of sphalerite is caused by the activation of the mineral by the lead ions present in the flotation pulp. Further evidence of th e activation mechanism was given by examining the surfaces of the mono minerallic sphalerite specimens that had been immersed in the flotatio n pulp and other solutions containing lead ions; XPS analysis of the s pecimens showed significant amounts of lead on the surface. When the s pecimen was contacted by ore pulp (or simulated plant water) and then with a xanthate solution, the Fourier Transform Infrared (FTIR) spectr um of the specimen showed the presence of lead xanthate and dixanthoge n. The proposed activation mechanism is discussed in view of the therm odynamic data available in the literature. Copyright (C) 1996 Publishe d by Elsevier Science Ltd