The green separation of sphalerite from pyrite: Triazine-dithione collector and its flotation mechanism

Under the traditional sulfhydryl collector system, the flotation enrichment of sphalerite requires the addition of copper ions to pre-activate sphalerite, and the separation of sphalerite and pyrite can be realized under high alkali conditions, which is not environmentally friendly. Therefore, it is urgent to develop highly selective collectors to achieve green separation of sphalerite and pyrite without copper ion activation and under low alkali conditions. In this study, 2-dibutylamino-4(1 H)-thione-6-thiol-1,3,5-triazine (DBN) was first selected as a specific collector for flotation separation of sphalerite from pyrite, and the selective hydrophobic mechanism of DBN on sphalerite surface was emphatically investigated. UV spectra showed a selective affinity of DBN towards zine ions rather than iron ions. The results of adsorption capacity indicated that under pH 4.0 ∼ 6.0, the adsorption amount of DBN on sphalerite was much higher than that on pyrite. In-situ atomic force microscopy (AFM) images combined with Contact Angle distinctly exhibited that the self-assembly of DBN on sphalerite improved its surface hydrophobicity. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) revealed that DBN chemisorbed on sphalerite surface via bonding DBN’s exo -S atom with surface Zn atom. Due to the selective adsorption, DBN efficiently floated out sphalerite from pyrite at natural pH (∼5.9) in the absence of extra agents such as lime, activators and depressants. Therefore, DBN achieved the green separation and enrichment of sphalerite from pyrite, which offered a novel insight for developing green and efficient collectors.