Migration and Conversion of Al Element in the Hydrometallurgical Preparation of Al2O3 from Secondary Aluminium Dross

The amount of secondary aluminium dross in China exceeds one million tons annually, posing environmental and disposal challenges. This study explores acid leaching as an alternative to conventional alkali methods for recovering Al from secondary aluminium dross to produce Al2O3. Research has focused on optimizing leaching conditions. Under optimized H2SO4 leaching conditions, an Al3+ leaching ratio of 86.5% is achieved. By maintaining a pH below 9 during hydrolytic precipitation and multiple washes, the leaching efficiency of Al from Al(OH)3 reached 95.97%. The original dross, which is primarily composed of Al, Al2O3, and AlN, undergoes a transformation where AlN becomes Al(OH)3 during washing. Thermal decomposition then yields Al2O3. The overall recovery of Al reaches 83.11%.