A useful method for separating light rare earth elements and heavy rare earth elements

摘要

An object of the present invention is to provide a method useful for separating a light rare earth element and a heavy rare earth element, which, for example, when a light rare earth element and a heavy rare earth element are separated from a workpiece containing a light rare earth element and a heavy rare earth element by a solvent extraction method, makes it possible to reduce the amount of extractant or organic solvent used or downsize the apparatus, or makes it possible to reduce the work burden on the process, such as the analysis of the content ratio between the light rare earth element and the heavy rare earth element contained in the workpiece. The method of the present invention as a means for resolution is characterized by including at least: (1) a step of obtaining, from a workpiece containing a light rare earth element and a heavy rare earth element, a composite oxide or mixture of oxides of the two; (2) a step of dissolving the obtained composite oxide or mixture of oxides of a light rare earth element and a heavy rare earth element in hydrochloric acid and/or nitric acid; (3) a step of adding a precipitant to the obtained solution to give a precipitate; (4) a step of calcining the obtained precipitate; (5) a step of adding the obtained calcine in an amount of 1.1 times to 3.0 times the upper solubility limit to hydrochloric acid and/or nitric acid having a concentration of 0.7 mol/L or more to give a solution and a residue; and (6) a step of separating the obtained solution and residue, thereby giving the solution as a light rare earth element-rich inclusion and the residue as a heavy rare earth element-rich inclusion (here, the term "rich" means that the content ratio of the concerned rare earth element to the other rare earth element is higher than the content ratio in the workpiece).