A Review of Germanium Recovery from Zinc Smelting Residues: From Enrichment to High-Purity Preparation

Germanium is a strategically critical metal with indispensable applications in infrared optics, fiber-optic communications, and semiconductor devices. Although previous reviews have extensively addressed the hydrometallurgical recovery of germanium from specific enriched materials and the associated extraction efficiencies, a systematic and integrated understanding of its migration behavior, occurrence states, and phase transformations across the entire zinc smelting process is still lacking. This review fills this gap by investigating the migration and enrichment characteristics of germanium in zinc smelting residues and by constructing a comprehensive framework encompassing occurrence, roasting, leaching, separation, and purification, covering the entire route from zinc concentrate to high-purity germanium production. By establishing this integrated analytical framework that traces the migration and enrichment pathways throughout the whole process chain, this review provides a valuable technical reference for elucidating the migration patterns of germanium in complex smelting systems, devising efficient recovery strategies, and advancing the sustainable utilization of germanium resources.