The selective flotation separation of galena from sphalerite with 5-heptyl-1,3,4-thiadiazole-2-thione: Emphasizing on adsorption mechanism

Abstract

In order to improve the flotation process, chemical engineering plays a significant role, particularly in the development of novel collectors. This paper utilized the novel collector 5-heptyl-1,3,4-thiadiazole-2-thione (HPSDT) to separate galena from sphalerite. The micro flotation demonstrated that HPSDT exhibited an excellent selectivity towards galena, and achieved the efficient flotation separation of galena from its mixture with sphalerite at pH 10. And HPSDT exhibited the greater hydrophobization to galena than sphalerite under pH 4–12. Overall, with lifting temperature, the contact angle of galena and sphalerite decreased, so did their flotation recovery. In situ AFM analyses indicated that HPSDT self-assembled on the galena surface to form aggregates, while no any aggregation was observed on the sphalerite surface. UV spectra reconfirmed the selective adsorption of HPSDT on galena rather than sphalerite. The adsorption of HPSDT on to galena was in good agreement with the pseudo-second-order model and Langmuir isotherm, which was a spontaneous exothermic chemisorption process. FTIR and XPS analyses indicated that the HPSDT-Pb complexes were formed on galena surface through the interaction of surface Pb atoms with the N and S atoms of HPSDT, which oriented HPSDT’s heptyl group outward to adhere bubbles, and then to be hydrophobized and floated out.