Strong magnetic and ultrasonic fields enhanced the leaching of Ga and Ge from zinc powder replacement residue

Abstract

Gallium (Ga) and Germanium (Ge) are crucial strategic resources with extensive applications in high-tech industries. However, Ga and Ge primarily occur as associated minerals. The process involves the leaching of lead–zinc ores and subsequent leaching to recover the valuable elements. The conventional acid leaching procedure exhibits low leaching effectiveness for Ga and Ge, making their recovery challenging. This study initially investigated the occurrence states of Ga and Ge. The thermodynamic simulations were used to investigate the feasibility of Zinc powder replacement residue (ZPRR) in a two-stage acid leaching process. The leaching mechanism in the strong magnetic field and ultrasonic field was studied using several characterizations such as XRD, SEM, XPS, FT-IR, etc. The investigation revealed that raising the temperature in the acidic solution led to an enhanced leaching efficiency of Ga and Ge. However, at 120 °C, the leaching efficiency of Ge decreased due to the hydrolytic precipitation occurring between Ge and SiO2. Nevertheless, the utilisation of a strong magnetic field proved advantageous in impeding this process. Furthermore, the application of the combined ultrasonic field contributed to enhancing the level of residue refining, hence promoting the effectiveness and degree of the reaction. Thus, the leaching efficiency of Ga and Ge was influenced by temperature, strong magnetic field, and ultrasonic field in combination. The high leaching efficiency of 95.53 % and 97.11 % for Ga and Ge, respectively, could be attained in the optimal experimental parameters. This study offers theoretical guidance for the effective and environmentally friendly leaching of Ga and Ge. Furthermore, it has been observed that this method is also promising for leaching the other valuable metals.