Removal of Aluminum Nitride from Secondary Aluminum Ash and its Aluminum Recovery

The aluminum nitride in the secondary aluminum (Al) dross release ammonia gas when it contacts with water. Therefore, the aluminum nitride poses a serious security threat to the environment. Denitrification is an important way to realize the harmless and resource utilization of secondary aluminum ash. A denitrification process of secondary Al ash was developed in this study. The influences of reaction temperature, reaction time, liquid-solid ratio on the denitrification ratio of secondary Al ash were explored, and the recycling rate of aluminum was also investigated.The results showed that satisfactory denitrification results can be achieved by keeping reaction temperature at 80～95 °C for 3～5 h, and controlled liquid-solid ratio at (4～12):1, the maximum denitrification ratio can reach 97.5%. Considered cost and treatment efficiency, the recommended denitrification parameters were 80 °C, 3 h and liquid-solid ratio of 6:1, and the aluminum loss rate decreased from 5% to 0.29% at these conditions. The denitrification process developed in this study has demonstrated its advantages in lower cost and higher efficiency, and it can further reduce the loss of aluminum resources to improve its reutilization.