A phosphorylated ketone, 5-(diphenylphosphoryl)hexan-3-one, as a new effective extractant for the recovery and separation of lanthanides in the eudialyte processing

The increased consumption of rare earth elements (REEs) requires processing of new lowprofitable mineral raw materials such as ores with low REE con� tents and industrygenerated wastes of various origin (chemical plant wastes, spent nuclear fuel and so on). Eudialyte containing up to 2.5% lanthanide impurities is a highly promising "nontraditional" mineral for the recovery of lanthanides (1). The elemental composi� tion of lanthanides in eudialyte is characterized by high (up to 50% of the lanthanide sum) contents of heavy lanthanides, which makes eudialyte a valuable mineral raw material for the recovery of rare earth elements. This distinguishes eudialyte from other known minerals such as apatite or loparite, in which the content of most expensive yttrium group lan� thanides is much lower (2). Eudialyte is readily digested with acids without preliminary activation, which markedly facilitates the industrial processing of the mineral (3). Since eudialyte contains consider� able amounts of some other valuable components (zirconium, scandium), apart from lanthanides, a topical task is to develop an integrated processing technology for this mineral. The traditional ore processing flow charts include leaching with concentrated mineral acids and recovery of rare earth elements by multistep liquid extraction (3-6). In the processing of raw materials with low contents of valuable components (eudialyte, apatite, or fluoroapatite ores), it is especially important to choose an appropriate extractant, because the known neutral organophosphorus extractants (NOPCs) have rather low distribution ratios and separation levels for lanthanides and extract actinides at almost the same level. Therefore, the search for new effective, synthet� ically accessible, and commercially attractive extract� ants for the recovery and separation of rare earth ele� ments remains topical.