PROCESSING ROUTE FOR DIRECT PRODUCTION OF MIXED RARE EARTH METAL OXIDES BY SELECTIVE EXTRACTION

摘要

The process of the present invention comprises extracting praseodymium, neodymium, and optional cerium from a first aqueous solution comprising chlorides or sulfates of light rare earth into an organic solution; and separating product praseodymium, neodymium, and optional cerium from the organic solution by stripping the praseodymium, neodymium, and optional cerium into a second aqueous solution, followed by precipitation from the second aqueous solution, or by precipitating the praseodymium, neodymium, and optional cerium directly from the organic solution. The process is particularly advantageous because it allows efficient production of a mixture of rare earth suitable for use for permanent magnets that is less expensive and more readily available than the presently used pure neodymium. The extractant is selected from neodecanoic ("versatec") acids, naphthenic acids and organophosphorous compounds including i.a. 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (EHEHPA) and tributylphosphate (TBP).