National University of Science and Technology MISIS, Moscow, Russia:

А. А. Kayumov, Postgraduate Student, Department of Benefication and Minerals and Man-Made Materials Processing, e-mail: maliaby_92@mail.ru
D. D. Aksenova, Postgraduate Student, Department of Benefication and Minerals and Man-Made Materials Processing
М. А. Belokrys, Master’s Student, Department of Benefication and Minerals and Man-Made Materials Processing
P. R. Malofeeva, Postgraduate Student, Department of Benefication and Minerals and Man-Made Materials Processing

This paper describes the results of an experimental study that looked at the combined effect of sodium thiosulfate and butyl xanthate or M-TF (a mixture of thionocarbamate and dithiophosphate) on the floatability of tennantite and pyrite, the relative adsorption of butyl xanthate and M-TF, wettability and the zeta potential at pH 8 and 12.5. The authors found that the floatability of tennantite and pyrite tend to go down as the concentration of sodium thiosulfate rises. The initial concentration of thiosulfate ions of 300 mg/l and higher would naturally impact the floatability of tennantite and pyrite, the adsorption of butyl xanthate and M-TF, as well as the wetting angle on sulphides. At pH 8 and in the presence of sodium thiosulfate (up to 300 mg/l) with M-TF, tennantite remains flotation responsive, and pyrite is almost unfloatable. When using the “thiosulfate – collector” complex, the relative adsorption on tennantite and pyrite would also drop as the concentration of thiosulfate rises. If the concentration of thiosulfate does not exceed 300 mg/l and the pH level is 8, M-TF would be adsorbed more on tennantite than on pyrite. The wetting angle of tennantite, to which M-TF only was applied, is 65 degrees. If butyl xanthate is applied, the angle is 50 degrees, and it is 50 and 70 degrees for pyrite, correspondingly. When sodium thiosulfate is present, the contact angle becomes smaller on either tennantite or pyrite. The angle can be bigger on tennantite if the “thiosulfate – M-TF” complex is applied. The “thiosulfate – M-TF” complex leads to a predominant surface hydrophilisation of pyrite almost within the entire range of sodium thiosulfate concentrations in view. In the presence of sodium thiosulfate and at pH 8 with M-TF and butyl xanthate, the zeta potentials of ultrafine tennantite and pyrite particles (4 μm) have close values, which indicates the non-selectivity of ultrafine sulphide slimes. With the help of an experimental study involving monominerals, the authors demonstrate that tennantite can be more floatable at pH 8 if M-TF is applied (C = 10–4 mol/l). The recovery of tennantite and pyrite in a concentrate drops as the initial concentration of thiosulfate rises to 300 mg/l and higher. The results of the study suggest how the contrasting flotation properties of tennantite and pyrite can be enhanced in a weakly alkaline limy medium (pH 8) in the presence of M-TF and thiosulfate (up to 300 mg/l). Thus, these findings could be useful when developing flotation regimes involving reagents.
This research was funded by the Russian Foundation for Basic Research under the Project No. 18-35-00213.

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