SEQUENTIAL SEPARATION METHOD FOR URANIUM AND RARE EARTH ELEMENT USING SUPERCRITICAL FLUID AS EXTRACTION MEDIUM

摘要

PURPOSE: To selectively and sequentially extract and separate even co-existing uranium and a rare earth element using a supercritical fluid as a medium by providing a plurality of extraction processes of different extraction efficiency. CONSTITUTION: Tributyl phosphate(TBP) and carbon dioxide are mixed through a syringe pump 1 and a plunger pump 3, so as to obtain TBP concentration at 3vol%, and a mixture so obtained is processed into a supercritical fluid at 60 deg.C and 150atm, by use of a preheater coil 5. Then, the fluid is made to flow into a sample solution in an extraction vessel 6 at a constant flowrate of approximately 1.1ml/min. Then, an effluent from the vessel 6 is passed through a filter 7 and a restrictor 8 and, then, uranium and a rare earth element are separately arrested with an arrester vessel 9. Also, carbon dioxide is separately collected from a gas outlet into a gas arrester. In this case, the filter 7 has a function of arresting particulate solid substances contained in the extracted fluid, in order to prevent the internal space of the capillary of the restrictor 8 from being clogged. Furthermore, the restrictor 8 gasifies carbon dioxide in the supercritical fluid after the return thereof to a normal temperature and pressure state.