PROBLEM TO BE SOLVED: To provide a method for eluting a heavy rare earth element from a light rare earth element and a heavy rare earth element-containing treatment object, from a light rare earth element and a heavy rare earth element treatment object, for separating both of the same as an alternative technique for a solvent extraction method.SOLUTION: Provided is a method at least comprising: a step (1) where, from a light rare earth element and a heavy rare earth element-containing treatment object, a mixture of the composite oxide or oxide of both the same is obtained; a step (2) where the obtained mixture of the composite oxide or oxide of the rare earth element and the heavy rare earth element is fired together with an aluminum source; a step (3) where the obtained fired material is added to hydrochloric acid and/or nitric acid with a concentration of 0.1 to 3.0 mol/L; and a step (4) where the heavy rare earth element-containing solution is separated from the residue.SELECTED DRAWING: Figure 1
展开▼