Synthesis of a novel collector based on selective nitrogen coordination for improved separation of galena and sphalerite against pyrite

During the separation of sulfide minerals, the problem of low selectivity always arises. A novel thiadiazole derivative (CSC-1) was developed for the flotation of sulfide minerals. The results of flotation tests showed that, compared with the conventionally-used ethyl xanthate, using CSC-1 as the collector, higher flotation recoveries of sphalerite and galena with improved selectivity against pyrite were obtained. Furthermore, zeta potential measurement and FTIR-spectra analysis results revealed that CSC-1 preferred to adsorb onto sphalerite and galena, rather than onto pyrite. The interaction mechanisms of CSC-1 with sphalerite and galena are electrostatic forces and chelation by forming N-Pb-S / N-Zn-S coordination bonds. DFT calculations demonstrated that both the Gibbs free energy difference (Delta G) and the distortion energy difference (AD) of metal ion-CSC-1 configuration before and after coordination follow the order: Pb2+-CSC-1 < Zn2+-CSC-1 < Fe2+-CSC-1, which further confirmed CSC-1 has preferable chelating selectivity towards Pb2+ and Zn2+, rather than Fe2+. This study indicates that CSC-1 has great potential for industrial application in sulfide mineral flotation. (C) 2020 Elsevier Ltd. All rights reserved.