| Abstract Scope |
Domestic red mud is an underutilized resource for gallium (Ga) and associated critical elements. However, recovery is limited by complex mineralogy, iron co-dissolution, and silica gel formation. This study compares acidic lixiviants (hydrochloric, sulfuric, and nitric acids) and alkaline lixiviants (sodium hydroxide and potassium hydroxide) for extracting Ga, aluminum (Al), and zinc (Zn) from domestic red mud. Leaching was evaluated as a function of reagent concentration, liquid-to-solid ratio, temperature, time, and agitation speed to identify conditions favorable for the recovery of critical metals and downstream processing. Among acidic systems, sulfuric acid achieved the strongest overall dissolution, extracting 25% Ga, 100% Al, and 100% Zn. Among alkaline systems, potassium hydroxide gave the highest Ga recovery, extracting 34% Ga, 100% Al, and 70% Zn. Silica gel formation was observed among all acidic lixiviants. These results provide a basis for understanding the potential to recover critical metals from red mud. |