Strengthening Sulfidation Flotation of Hemimorphite via Pretreatment with Pb2+

The conventional sulfidation-xanthate flotation process that consists of sulfidization with sodium sulfide, activation by heavy-metal ions, and collection with xanthate is not sufficiently efficient for treating hemimorphite, and the dosages of the sulfurizing reagent and metal ions are large. In this study, the sulfidation flotation (Pb2+ + Na2S + Pb2+ + xanthate) of hemimorphite was strengthened by pretreating with Pb2+ before sulfidation. Microflotation test results indicated that the recovery of hemimorphite increased by 5-10% after pretreatment with Pb2+. The comprehensive results of adsorption experiments, scanning electron microscopy-energy-dispersive X-ray spectroscopy, atomic force microscopy, and X-ray photoelectron spectroscopy indicated that a large amount of Pb2+ was adsorbed on the hemimorphite surface and entered the lattice, forming Zn(4-x)PbxSi2O7(OH)(2)center dot H2O. The newly formed component had an increased amount of surface sulfidation active sites and had the effect of induced crystallization, making the surface more effective for sulfidation. After the Pb2+ was added to the pulp, a large number of uniform and dense PbS species were formed on the hemimorphite surface, increasing the number of adsorption sites for xanthate and reducing the competitive adsorption of residual S2- on the xanthate.