Novel insight into the lead sulfide species formed on hemimorphite surface during lead ions improved sulfidation

Abstract

Hemimorphite always required the activation by lead ions (Pb2+) to realize recovery in the sulfidation-xanthate flotation. However, there is no accurate description of the formation of lead sulfide species on the hemimorphite surface after Pb2+ activation. Herein, micro-flotation experiments, ICP-OES tests, Visual MINTEQ calculation, XPS analysis, TOF-SIMS analysis and contact angle measurements were investigated to elucidate it. The micro-flotation experiment results demonstrated that the stable adsorption of Pb2+ on the surface could improve the floatability of hemimorphite. Visual MINTEQ calculation results suggested that PbS was easier to form and saturate than ZnS in the pulp solution containing Pb2+. XPS and TOF-SIMS analysis results further confirmed the generation of PbS and ZnS on the hemimorphite surface. Except for the ion-exchange reaction with ZnS to form PbS, Pb2+ species could interact with the -OH components on the hemimorphite surface via the dehydration reaction to produce -O-Pb complexes. The formation of -O-Pb complexes increased the adsorption site of sulfur components on the hemimorphite surface, resulting in more PbS species precipitating on the hemimorphite surface. Overall, all results showed that Pb2+ was essential to improving the floatability and hydrophobicity of hemimorphite.