Dissolution behavior and improvement approach for gallium extraction from zinc refinery residues

Aiming at solving low Ga leaching efficiency during actual industrial production in Danxia Smelter, chemical composition, phases and morphologies of various zinc refinery residues were characterized using ICP−AES, XRD and SEM−EDS. Compared with the normal material, Ga was embedded in the jarosite phase from the special zinc refinery residue, causing difficulty in Ga leaching. During the oxidation pressure leaching, the dissolution behaviors of Ga, As and Fe presented similar variation tendency. Namely, a sufficient H2SO4 concentration and liquid-to-solid ratio promoted the dissolution of Ga, Fe and As, whereas higher reaction temperature and oxygen partial pressure weakened the leaching. Based on the results, leaching parameters were optimized for enhancing Ga recovery. Through weakening the 1st oxidation pressure leaching (by decreasing reaction temperature and total pressure to 90 °C and 0.2 MPa, respectively) and strengthening the 3rd atmospheric leaching (by increasing H2SO4 concentration and reaction temperature to 160 g/L and 85 °C, respectively), the leaching efficiency of Ga increased from 77.83% to 96.46%.