| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method by which a solution containing high-purity valu able metal can be obtained by easily removing manganese from a solution prepared by dissolving electrode active material with sulfuric acid in the case of recovering valuable metal, such as nickel and cobalt, from a used nickel- hydrogen secondary battery. SOLUTION: The electrode active material is dissolved with the sulfuric acid, and the resultant solution is held at <=pH 3 and also ORP is regulated in a range of 1,000 to 1,200 mV to precipitate and remove manganese. For the purpose of pH regulation for the solution, trivalent nickel and/or cobalt hydroxide is added as an oxidizing agent. As to another method, manganese can also be precipitated and removed by holding the above solution at 50-90 deg.C reaction temperature and pH 1 to 5.5 and adding ammonium persulfate or sodium persulfate.</p> |
