Method for preferentially recovering manganese from waste lithium-rich manganese-based cathode material

A method for preferentially recovering manganese from a waste lithium-rich manganese-based cathode material, comprising:

• step 1) calcining and leaching:
• mixing the waste lithium-rich manganese-based cathode material with ammonium sulfate and then performing low-temperature calcination to obtain a calcination product, leaching the calcination product with water, and performing solid-solution separation after the completion of the water leaching to obtain leaching residue and a leaching solution;
• step 2) complexing and manganese separating:
• adding ammonium sulfite to the leaching solution obtained in step 1) for a complex reaction, aging after the completion of the complex reaction, and filtering after the completion of the aging to obtain manganese-rich residue and a manganese-separated solution;
• in step 2), the amount of ammonium sulfite added is 3-5 times @ theoretical value of manganese complex in the leaching solution;
• and in step 2), when the complex reaction is performed, the pH value of the complex solution is adjusted to 7-10 with ammonia water;
• the complex reaction temperature is 25-70° C.;
• the complex reaction time is 20-60 min;
• and the aging time is 1-8 h;
• step 3) oxidation leaching:
• adding an oxidant to the manganese-rich residue obtained in step 2) to perform oxidation leaching, adding 98% concentrated sulfuric acid to adjust the pH of the solution, and obtaining a manganese-rich solution after the completion of the reaction;
• in step 3), when performing oxidation leaching, the oxidant is hydrogen peroxide;
• the amount of hydrogen peroxide added is 0.5-2 mol per liter of the solution;
• and the solid-solution ratio of the leaching is 1:5-1:20 g/mL;
• and in step 3), the pH of the solution is adjusted to 1-5 with 98% concentrated sulfuric acid;
• the leaching temperature is 25-60° C.;
• and the leaching time is 10-25 min;
• and
• step 4) extracting and stripping:
• performing multi-stage extraction of manganese on the manganese-rich solution obtained in step 3) to obtain a manganese-loaded organic phase and a raffinate;
• mixing the raffinate with the manganese-separated solution obtained in step 2) for a recovery treatment, and stripping the manganese-loaded organic phase to obtain a manganese sulfate solution.