National University of Science and Technology “MISiS”, Moscow, Russia:

B. E. Goryachev, Professor, Department of Mineral Processing and Technogenic Raw Materials
Naing Linoo, Post-Graduate Student, Department of Mineral Processing and Technogenic Raw Materials
A. A. Nikolaev, Assiociate Professor, Department of Mineral Processing and Technogenic Raw Materials, e-mail: nikolaevopr@mail.ru
A. A. Zhebrikova, Master's Degree Student, Department of Mineral Processing and Technologenic Raw Materials

We show the results of thermodynamic calculations of the collector adsorption layer formation on pyrite surface in sulphydryl collectors' water solutions at pH = 8–12. Potassium butyl xanthate and sodium dibutyl dithiophosphate were used as collectors. The calculations were made for the case of pyritic sulphur oxidation to elemental or thiosulphate sulphur. Composition of the collector's adsorption layer on mineral surface depended on oxidation degree of pyritic sulphur. In the initial stage of oxidation, formation of physically adsorbed collector (butyl dixanthogen or dibutyldithiophosphate) was likely took place. The degree of pyritic sulphur oxidation did not affect the probability of either chemical or physical xanthate adsorption on pyrite surface. We carried out the potentiometric measurements of pyrite electrode potential in alkaline water solutions (pH = 10) of butyl potassium xanthate and sodium dibutyl dithiophosphate in a variable concentration. Lime was used as a pH reagent. Introduction of collector into alkaline water solution led to decrease in the oxidation-reduction potential of the solution, which indicates the reducing properties of used collectors. The potential of pyrite electrode remained constant with a change in thiol collector solutions concentration, which indicates the impossibility of collectors interaction with the electrode surface under these conditions. The platinum electrode potential was functionally dependent on the concentration of xanthate ions in water solution and was practically independent in the case of sodium dithiophosphate solutions. Therefore the possibility of dixanthogen formation on pyrite surface may be a result of xanthate ions oxidation by dissolved oxygen in the liquid phase and difficulties of such oxidation in the case of dibutyl dithiophosphate ions.

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