Recovery of gallium from Bayer red mud through acidic-leaching-ion-exchange process under normal atmospheric pressure

The Bayer red mud (BRM), generally containing 0.002 wt%-0.008 wt% of gallium (Ga), is an overlooked resource of Ga. In this work, an efficient method, called acidic-leaching-ion-exchange process (ALIEP), was developed to extract Ga from BRM. The ALIEP method involved three main steps: the BRM sample was firstly dissolved by mineral acid and the obtained leaching solution was further purified to remove the Fe3+ Consequently, the purified solution, pre-concentrated by re-circulation process, was efficiently treated by ion exchange process for the Ga recovery. The main influencing factors of the acidic-leaching process were systematically investigated. The optimal Ga leaching conditions were determined as HC1 +/- 159 g/L, liquid-to-solid ratio of 8 mL/g, 55 degrees C, and 5 h, attaining Ga leaching rate of 94.77% and the corresponding Ga3+ concentration of 3.91 mg/L in leachate. A nearly complete iron removal from the leachate was achieved by employing LSD-396 resin under conditions of 45 +/- 2 degrees C, resin dosage of 0.6 g/mL and 2 h. Subsequently, the recovery efficiency of Ga from re-circulation leaching solution using the ion-exchange technology was evaluated. The results indicated that an adsorption rate of 59.84% and desorption rate of 95.32% for Ga were obtained. The concentrated solution contained 97.54 mg/L of Ga, which was enriched 24.95 and 4.75 times compared to the initial leaching solution of 3.91 mg/L and re-circulation solution of 20.52 mg/L, respectively.