Recovery of scandium from various sources: A critical review of the state of the art and future prospects

Scandium is a critical metal in increasing demand for modern technologies, such as light-weight aluminumscandium alloys. Evaluating current and identifying new sources of the element has become a pressing need in order to provide a reliable and cost effective future supply. As current resources are limited, new sources must be explored with due consideration for the environmental aspects of the mining and processing technologies. The present review considers scandium extraction from three different sources - primary, secondary and opportunities - focusing on clean technologies and eco-friendly processing to achieve goals 7, 8, 9, and 12 of the 17 sustainable development goals of the United Nations. The main scientific databases were explored using keyword combinations. The question "is it possible to have an ecofriendly process for scandium extraction?" - worldwide debated - was answered providing diversified opportunities for scandium extraction, demonstrating that the current development would achieve these goals. Several techniques were explored and compared. As important as technical studies, economic approaches must be deeply evaluated where both acid consumption and downstream refining are equally challenging.