Recycling of Primary Lithium Batteries Production Residues

Production waste of primary lithium batteries constitutes a considerable secondary lithium feedstock. Although the recycling of lithium batteries is a widely studied field of research, the metallic residues of non-rechargeable lithium battery production are disposed of as waste without further recycling. The risks of handling metallic Li on a large scale typically prevent the metal from being recycled. A way out of this situation is to handle Li in an aqueous solution, from where it can be isolated as Li2CO3. However, the challenge in hydrometallurgical treatment lies in the high energy release during dissolution and generation of H-2. To reduce these process-related risks, the Li sheet metal punching residues underwent oxidative thermal treatment from 300 to 400 degrees C prior to dissolution in water. Converting Li metal to Li2O in this initial process step results in an energy release reduction of similar to 70 %. The optimal oxidation conditions have been determined by experimental design varying three factors: temperature, Li metal sheet thickness, and residence time. With 96.9 +/- 2.6 % almost the entire Li amount is converted to Li2O, after 2.5 h treatment at 400 degrees C for a Li sheet thickness of 1.99 mm. Final precipitation with CO2 yields 85.5 +/- 3.0 % Li2CO3. Using pure Li sheets, the product Li2CO3 is obtained in battery-grade quality (>99.5 %). Non-precipitated Li is recirculated into the process on the stage of dissolving Li2O, thus avoiding loss of material.