National Research Tomsk State University, Tomsk, Russia:

V. I. Sachkov, Associate Professor, Head of the Chemical Technology Laboratory, Doctor of Chemical Sciences
R. A. Nefedov, Senior Researcher, Candidate of Chemical Sciences
I. V. Amelichkin, Junior Researcher
R. O. Medvedev, Junior Researcher, e-mail: rodionmedvedev7@gmail.com

This paper looks at the tailings of collective and zinc flotation. Thus, the authors examined elemental and phase compositions of primary material, as well as the distribution of elements on grain surface. It was established that pyrite material is not easily processable and the application of classical cyanide process to it would lack cost efficiency. The paper examines the applicability of sulphite-sulphate leach solutions for gold extraction into liquor and the effect of process parameters on gold recovery when using sodium sulphite and sodium suphate containing solutions. It was found that if the total concentration of lixiviants exceeds 0.15 mol/L, the gold balance tends to shift towards the solid phase, which may be attributed to a decreased activity of complexing ligands linked to a rising ionic strength of the solution. The minimum gold concentration in the liquor was registered at pH = 8…9, which may well be attributed to a passivating film that forms out of adsorbed oxygen and gold hydroxide Au(OH)₃. It was established that the recovery of gold tends to drop as the process duration increases. Thus, the maximum concentration of gold in the liquor was reached in the first hour of the process. After that the concentration tends to drop as the complex decomposes and gold precipitates in metallic form or in the form of insoluble compounds. The highest recovery of gold into liquor was reached at a concentration of sodium sulphite and sodium sulphate of 40 and 35 mmol/L, correspondingly; pH = 7, process duration of 1 hour and ambient temperature. The above combination of process parameters resulted in a 67% recovery.
Contributors to this paper include junior researcher P. S. Shcherbakov, junior researcher D. I. Leonov, junior researcher V. S. Soloviev, associate professor A. S. Sachkova, Candidate of Biological Sciences; laboratory assistant D. A. Biryukov.

1. Decree No. ‘2914-р’ by the Government of the Russian Federation dated 22 December 2018 ‘On the Development Strategy for the Minerals Sector of the Russian Federation till 2035. Available at: https://www.garant.ru/products/ipo/prime/doc/72038606/.
2. Barani K., Kogani Y., Nazarian F. Leaching of complex gold ore using a cyanide-glycine solution. Minerals Engineering. 2022. Vol. 180. 107475.
3. Sitando O., Dai X., Senanayake G., Nikoloski A. N., Breuer P. A fundamental study of gold leaching in a thiosulfateoxygencopper system in the presence of activated carbon. Hydrometallurgy. 2020. Vol. 192. pp. 105232–105232.
4. Liu X., Jiang T., Xu B., Zhang Y., Li Q. et al. Thiosulphate leaching of gold in the Cu – NH₃ – S2O₃^2– – H₂O system: An updated thermodynamic analysis using predominance area and species distribution diagrams. Minerals Engineering. 2020. Vol. 151. pp. 106336–106336.
5. Lakshmanan V. I., Roy R., Gorain B. Gold and Silver Extraction. Innovations and breakthroughs in the gold and silver industries. Cham : Springer International Publishing. 2019. pp. 29–110.
6. Lodeyshchikov V. V. A process for extracting gold and silver from refractory ores. Irkutsk : Irgiredmet, 1999. 452 p.
7. Mineev G. G., Panchenko A. F. Gold and silver solvents in hydrometallurgy. Moscow : Metallurgiya, 1994. 241–241 p.
8. Kenna K. K. Method of hydrometallurgic gold extraction from the goldcontaining material. Patent AU PI 8790. Published: 20.10.95. Priority: 23.02.90.
9. Aylmore M. G., Muir D. M. Thiosulfate leaching of gold – a review. Minerals Engineering. 2001. Vol. 14, No. 2. pp. 135–174.
10. Anderson C. G. The industrial non-cyanide hydrometallurgical recovery of silver and gold utilizing nitrogen species catalysed pressure oxidation. Hydrometallurgy. 2003. 2003. Vol. 1. pp. 89–104.
11. McNulty T. Cyanide substitutes. Mining Magazine. 2001. Vol. 184, Iss. 5. pp. 256–261.
12. Gos S., Rubo A. The relevance of alternative lixiviants with regard to technical aspects, work safety and environmental safety. Cyplus. Degussa AG, Hanau, Germany. 2001.
13. Polezhaev S. Yu., Fomenko I. V., Pleshkov M. A., Chugaev L. V. Sulphite method of definition of oxidate gold in sulfides. Tsvetnye Metally. 2015. No. 2. pp. 58–63.
14. Hannington M. D., Scott S. D. Sulfidation equilibria as guides to gold mineralization in volcanogenic massive sulfides: evidence from sulfide mineralogy and the composition of sphalerite. Economic Geology. 1989. Vol. 84, Iss. 7. pp. 1978–1995.
15. Genik-Sas-Berezowsky R. M., Sefton V. B., Gormely L. S. Recovery of precious metals from metal sulfides. Patent US 4070182 USA. Published: 1978.
16. Kiselev E. A. On the status and use of mineral raw materials of the Russian Federation in 2019: State report. Moscow, 2020. pp. 311–332.
17. Kantemirov V. D., Titov R. S., Yakovlev A. M. Evaluation of the potential and technology for development of deposits of copper-pyrites ores in the circumpolar Ural zone. Metallurgist. 2019. Vol. 62, No. 11–12. pp. 1173–1180.