Enhanced selective hydrophobicity performance at solid-liquid interface during separation of chalcopyrite from galena with 5-methyl isobutylxanthate-1,3,4-oxadiazole-2-thione

Abstract

In order to improve the separation efficiency of copper and lead minerals, reduce the use of inhibitors, and further break the design bottleneck of the flotation collector, a novel compound with a di-minerophilic group was designed as a collector used for separating copper and lead minerals. In this study, novel oxadiazole-thione surfactants with or without a di-minerophilic group, including 5-methyl isobutylxanthate-1,3,4-oxadiazole-2-thione (MIXODT) and 5-heptyl-1,3,4-oxadiazole-2-thione (HpODT), were synthesized and introduced initially as collectors in flotation separation of chalcopyrite from galena. Micro-flotation indicated that MIXODT exhibited improved flotation ability and selectivity for chalcopyrite than HpODT. Meanwhile, DFT calculations also showed that the reactivity of MIXODT was higher than HpODT. The MIXODT's better selective adsorption behavior was characterized by wettability measurements, ζ-potential and UV spectra. The results of adsorption thermodynamic and kinetic experiments confirmed that MIXODT adsorption on chalcopyrite was an endothermic-spontaneous chemisorption process, with ΔH (change of enthalpy), ΔS (change of entropy), ΔG (change of free energy) and Ea (activation energy) values of 59.74 kJ·mol−1, 274.70 J·mol−1·K−1, -23.02 kJ·mol−1 and 58.68 kJ·mol−1, respectively. The electrochemical behavior of the chalcopyrite surface showed that a dense adsorption layer was formed on the chalcopyrite surface after MIXODT treatment.