| abstract |
(57) [Abstract] [Problem] From a positive electrode active material for a lithium ion secondary battery, Valuable metals such as cobalt and nickel are recovered at a high extraction rate. SOLUTION: After adding a mineral acid and hydrogen peroxide or a mixed solution of a mineral acid and hydrogen peroxide to a positive electrode active material for a lithium ion secondary battery, a first step of separating an eluate, and then a separated eluate A second step of contacting an organic solvent containing a metal extractant with the organic solvent to perform extraction and separation treatment, and then a third step of back contact extraction and separation by bringing a mineral acid into contact with the organic solvent phase of the extract. |