Siberian scientists synthesized a new reagent for the extraction of precious metals. It will allow faster and cheaper extracting silver from ores, as well as from solutions during the secondary processing of valuable raw materials. The results are published in the journal Hydrometallurgy.

Noble metals, such as silver, platinum or palladium, are not present in ores or in secondary raw materials in pure form. As a rule, the content of precious elements in such compounds does not exceed several milligrams per kilogram, while the bulk of the rock is made up of impurities. To extract valuable compounds from ore or solution, extractants are added to them - substances which can selectively extract individual components. Many extractants are too expensive, or their use implies a complex and lengthy process, which is poorly suited for industrial applications.

Scientists of the Federal Research Center Krasnoyarsk Science Center SB RAS synthesized a reagent which is able to efficiently isolate precious metals from various technological mixtures and then easily concentrate them. This extractant can be used to extract precious elements from solutions obtained both in the processing of ores and secondary raw materials.

The substance created by the scientists is bisdithiophosphinic acid disulfide. It contains four sulfur atoms which form a bound ring with metal trapped inside. A high selectivity of the extractant is due to the fact that not all metals react equally with such complex compounds. Silver turned out to be most prone to interact with this reagent.

The process of separation of noble metals and impurities proceeds during the interaction of two phases: aqueous one with dissolved metals and organic one, i.e. the extractant. After mixing, the desired metal becomes bound to the reagent and, then, transformed into the organic phase. Further, silver or another metal can be isolated from the resulting solution in its pure form.

“The disulfide extractant can be used for various industrial silver-containing solutions. Its characteristics far exceed those of other reagents. For example, the ability of disulfide to extract - separate silver is significantly higher than that of widely known commercially available extractants. This makes it possible to more efficiently recover precious metals at lower cost. Moreover, the process itself proceeds very quickly, within a few minutes. We are currently studying the possibility of extracting palladium from various solutions using this extractant, ”says Natalya Grigoryeva, Candidate of Chemical Sciences, senior researcher at the Institute of Chemistry and Chemical Technology of the Krasnoyarsk Science Center SB RAS.