Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of Sciences – separate division of the Federal Research Center Krasnoyarsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, Russia

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

Various complexation agents (ethylene glycol, tartaric acid, citric acid, glycerin, trilon B, sugar, fructose) for the re-extraction of scandium in systems with di(2-ethylhexyl)phosphoric acid D2EHPA are considered. It has been shown that only saccharides can effectively re-extract scandium. It has been established that scandium compounds of different compositions are present in alkaline saccharide (sugar) solutions. When sorbitol is saturated with scandium, complexes with a scandium ratio are formed: saccharide, equal to 1:1 and 1:2. In addition, scandium anionic complexes are present in the solution, the proportion of which does not exceed 10%. The influence of various factors on the re-extraction of scandium from D2EHPA by alkaline saccharide solutions (concentration of alkali, saccharide, duration of phase contact, etc.) has been studied. It has been shown that in almost all cases the degree of re-extraction is close to 100%. The reextraction is carried out in a two-phase version without precipitation, unlike known methods, where it is performed in a solid-phase version in the form of hydroxide (Sc(OH)₃) or scandium fluoride (ScF₃). It is shown that scandium from the re-extracts can be extracted after acidification of solutions with mineral acids in the form of scandium hydroxide (Sc(OH)₃) or oxalate (Sc₂(C₂O₄)₃). Due to its simplicity and accessibility, scandium re-extraction with alkaline sorbitol solutions can be used in systems with D2EHPA for the extraction of scandium from various technological solutions.
This work was conducted within the framework of the budget project (project FWES-2021-0014) for Institute of Chemistry and Chemical Technology SB RAS using the equipment of Krasnoyarsk Regional Research Equipment Center of SB RAS.

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