Abstract
Metallic zinc is predominantly produced through the roast-leach-electrowinning process, where electrolyte purification prior to electrowinning is essential to prevent current efficiency losses and impurity co-deposition. Germanium, typically removed during iron co-precipitation, can enter the zinc dust cementation circuit and has been associated with unstable impurity behavior. This study investigates the influence of initial germanium concentration on impurity removal during zinc dust cementation under cold purification conditions. Batch experiments were conducted using synthetic electrolytes representative of industrial compositions, with controlled variation of initial germanium levels. Impurity concentrations and redox potential were monitored over time. Increasing germanium concentration resulted in a less reducing electrolyte environment and significantly promoted cadmium redissolution, with greater magnitude at higher levels. Although germanium was progressively removed from solution, cadmium instability persisted. In contrast, nickel, copper, and antimony were largely unaffected, while cobalt removal remained limited. These results demonstrate that germanium acts as a critical electrochemical modifier that selectively destabilizes cadmium.