Weak alkaline flotation separation of galena from sphalerite with 6-butylamino-1,3,5-triazine-2(1H)-thione-4-thiol sodium

The reduction of lime usage in flotation separation of lead–zinc sulfide ores has an interesting topic for protecting environment and recovering valuable metal minerals. In this study, BN (6-butylamino-1,3,5-triazine-2(1H)-thione-4-thiol sodium) was introduced for the first time as a selective collector for galena flotation. The results of UV spectra, adsorption capacity, zeta potential and in-situ AFM manifested that BN exhibited the selective affinity towards Pb2+ over Zn2+ ions, and preferred to adsorb on galena surface, not on sphalerite. The FTIR and XPS further uncovered that BN assembled on galena via bonding its sulfur atoms with lead ions of galena to form the surface BN-Pb complexes. The micro-flotation findings revealed that BN returned the stronger collecting power and higher selectivity than isobutyl xanthate during flotation separation of galena from sphalerite, and achieved their effective separation at low alkaline conditions (pH ∼ 8.0). This study also offers an enlightenment for the design of chelating collectors suitable for use under weak alkaline conditions.