Institute of Chemistry and Chemical Technology SB RAS, Federal Research Сenter “Krasnoyarsk Science Сenter” Siberian branch of Russian Academy of Sciences, Krasnoyarsk, Russia:

N. A. Grigorieva, Senior Researcher, e-mail: natasha@icct.ru
I. Yu. Fleitlikh, Leading Researcher

N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry of the Siberian branch of Russian Academy of Sciences, Novosibirsk, Russia:
A. Yu. Tikhonov, Chief Researcher

The paper presents the data on silver extraction from hydrochloric acid solutions with mixture of the disulfide of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (L) and alkylphenols of various structure in toluene. 4-tert-butylphenol, 2,6-dimethylphenol and 2,6-bis(tert-butyl)phenol, as well as n-octyl alcohol were used as additives. The introduction of the above additives into the organic phase in all cases resulted in a marked increase in extraction, that is to the synergistic effect (S). The following series of additives efficiency was obtained: 4-tert-butylphenol > 2,6-dimethylphenol > n-octyl alcohol > 2,6-bis(tertbutyl) phenol. It was concluded that the extraction of silver in a mixture of disulfide with 4-tertbutylphenol is due to the formation in the organic phase of a mixed complex of the composition [AgCl·2L·HR]. An increase of hydrochloric acid concentration leads to a decrease in the silver extraction due to the formation of non-extracting anionic silver complexes in the aqueous phase, as well as to a shift in the extraction equilibrium toward the initial components. The degree of silver recovery from hydrochloric acid solutions containing impurities (Ni, Cu, Co, Zn, Fe (III), Na), with mixture of disulphide and 4-tert-butylphenol in 3 stages of extraction was 99.5%, with high selectivity of the extractant. Silver stripping from the organic phase is achieved by using a thiourea solution in a mixture with sulfuric acid as a re-extractant. Mixtures of bis(2,4,4-trimethylpentyl)dithiophosphinic acid with alkylphenols should be used to extract silver from hydrochloric processing solutions of different origin.

1. Xu B.,Yang Y., Li Q., Li G., Jiang T. Fluidized roasting-stage leaching of a silver and gold bearing polymetallic sulfide concentrate. Hydrometallurgy. 2014. Vol. 147–148. pp. 79–82.
2. Harris G. B. Making use of chloride chemistry for improved metals extraction processes. Proceedings of the 7th International symposium on hydrometallurgy symposium on hydrometallurgy 2014 (HYDRO2014). Victoria, British Columbia, Canada, 22–25 June 2014. Vol. 1. pp. 171–184.
3. Natorkhin M. I., Garshin A. P. The method of silver recovery from concentrated chloride solutions. Patent RF, No. 2399687. Published: 20.09.2010.
4. Wejman-Gibas K., Pilsniak-Rabiega M. Studies of extractive removal of silver (I) from chloride solutions. E3S Web of Conferences. 2016. Vol. 8. Article number 01016.
5. Voropanova L. A., Kokoeva N. B. Extraction of silver ions from hydrochloric acid solutions with tributyl phosphate. Zapiski Gornogo instituta. 2016. Vol. 218. pp. 220–224.
6. Alam Shafiqul M., Inoue K., Yoshizuka K., Dong Y., Zhang P. Solvent extraction of silver from chloride media with some commercial sulfur-containing extractants. Hydrometallurgy. 1997. Vol. 44. pp. 245–254.
7. Torgov V. G., Tatarchuk V. V., Druzhinina I. A., Korda T. M., Renard E. V. Possibility of deep purification of fragmental palladium from silver by extraction with oil sulphides. Atomnaya energiya. 2000. Vol. 88. pp. 358–362.
8. Kostin G. A. S, PO-functionalized calixarenes: extraction and complexation of noble metals : thesis of Dissertation ... of Doctor of Chemical Sciences. Novosibirsk, 2014.
9. Paiva A. R. Extraction of silver from chloride solutions — how to establish the chemical reactions in Solvent Extraction. Proceedings of the ISEC’05. Beijing, China, 2005. pp. 74–80.
10. Ball G. A., Usoltseva M. V., Yudelevich I. G., Seryakova I. V., Zolotov Yu. A. Atomic absorption determination of silver after its extraction with diphenylthiourea. Zhurnal analiticheskoy khimii. 1976. Vol. 31, No. 1. pp. 27–31.
11. Fleitlikh I. Yu., Grigorieva N. A. The method of silver extraction from chloride solutions. Patent RF, No. 2631440. Published: 22.09.2017.
12. Grigorieva N. A., Fleitlikh I. Yu., Logutenko O. A. Silver Extraction from Hydrochloric Acid Solutions with the Disulfide of Bis(2,4,4-trimethylpentyl) Dithiophosphinic Acid. Solvent extraction and ion exchange. 2018. Vol. 36, No. 2. pp. 162–174.
13. Kuzmin V. I., Klimkina T. A., Logutenko O. A. Oxidation of cobalt (II) with disulfide during the extraction of di(2-ethylhexyl)dithiophosphoric acid. Zhurnal neorganicheskoy khimii. 1998. Vol. 43, No. 5. pp. 877–880.
14. Lure Yu. Yu. Handbook of analytical chemistry. Moscow : Khimiya, 1979. 480 p.
15. Pliev T. N. Spectroscopic study of the thermodynamic dissociation constants of alkylphenols. Doklady Akademii nauk SSSR. 1969. Vol. 184, No. 5. pp. 1113–1116.
16. Gordon A., Ford R. The Chemist’s Companion. Moscow : Mir, 1976. 542 p.
17. Kortum G., Vogel V., Andrussow K. Dissociation constants of organic acids in aqueous solution. London : Butterworths, 1961. 348 p.
18. Varentsov V. K., Belyakova Z. T. Silver electrolysis from thiourea solutions. Zhurnal prikladnoy khimii. 1983. No. 7. pp. 1554–1559.