Sorption processing of scandium-containing uranium production solution with a weak base anionite with primary amino groups

Solutions for underground uranium leaching are currently considered a promising source for recovering not only uranium, but also rare and rare earth elements that are highly valuable in various industries, from aerospace to electronics. However, the low concentrations of target components in such solutions, combined with the presence of a significant amount of associated and competing impurities, create serious technological difficulties in their selective extraction and subsequent production of compounds of the required degree of purity. This paper substantiates the possibility of effective recovery of scandium from hydrofluoric acid solutions formed at the Dalur JSC scandium by-product extraction site using secondary sorption technology on a weakly basic anion exchanger containing primary amino groups in its structure. It has been established that at a fluoride ion concentration of about 2 M, the total dynamic exchange capacity of the anionite for scandium reaches 49.7 g/dm3, which indicates the high selectivity of the material with respect to the target element. The paper describes a complex of research works aimed at obtaining commercial-grade scandium compounds - scandium oxide and scandium trifluoride - from a carbonate-containing eluate formed after desorption of the metal from the saturated anionite phase. Two approaches are considered: direct acid precipitation to obtain scandium trifluoride, and alkaline precipitation with the formation of scandium oxihydroxide, suitable for further oxalate precipitation to obtain commercial-grade scandium oxide. The use of the developed technology makes it possible to eliminate some of the intermediate precipitation operations and conversion stages characteristic of traditional schemes, which reduces the total losses of the target metal and increases the efficiency of processing. According to calculations, the overall recovery rate of scandium in the finished product reaches at least 95%, which is more than 30% higher than the rates achieved by the technology currently in use at the enterprise. In addition, the proposed method is technologically compatible with existing production lines, which simplifies its industrial implementation and minimises capital costs for equipment modernisation. Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interests.

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