Study of the Processes of Rare and Rare-Earth Metal Extraction from Ash and Slag MaterialsTatiana Cherkasova, Elizaveta Cherkasova, Anastasia Tikhomirova, Andrey Golovachev and Oleg DormeshkinE3S Web Conf., 174 (2020) 02031DOI: https://doi.org/10.1051/e3sconf/202017402031