Selective Adsorption Mechanism of Zinc Ions on the Surfaces of Galena and Sphalerite in the Flotation Separation of Pb-Zn

In this study, selective adsorption mechanism of zinc ions on the surfaces of galena and sphalerite in the flotation separation of Pb-Zn was comprehensively explored by flotation tests, Zeta potential measurements, Fourier transform interferometric radiometer (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) analysis, and density functional theory (DFT) calculations. Microflotation test showed that the use of ZnSO 4 in alkaline pulp could selectively separate galena from sphalerite better than that without ZnSO 4 . Zeta potential test results showed that ZnSO 4 could significantly increase the Zeta potential of sphalerite under alkaline conditions, but had little effect on galena. The results of FTIR test showed that xanthan characteristic peak appeared in xanthate-treated galena at pH = 10, while sphalerite treated with xanthate did not. XPS and DFT calculation results showed that sphalerite had stronger adsorption capacity for hydroxyl ions than galena. DFT calculation further confirmed that Zn(OH) 2 could be adsorbed on the surface of hydroxylated sphalerite instead of hydroxylated galena and formed a new interface microstructure of sphalerite (Zn surf -O-Zn-O-H), resulting in the inhibition of sphalerite. This paper further deepened the selective adsorption mechanism of zinc ions on the surface of sphalerite in the flotation separation of Pb-Zn under alkaline conditions.