ZINC REMOVAL FROM DILUTE-SOLUTIONS USING A ROTATING CYLINDER ELECTRODE REACTOR

Mine residue recycling processes produce dilute zinc solutions suitabl e for metal recovery. The rotating cylinder electrode reactor behaviou r sequentially followed charge transfer and diffusion control mechanis ms, even with solutions contaminated with metals or organic substances . Zinc removal at low pH (similar to 0) and low- concentration (simila r to 2mg dm(-3)) is demonstrated. Under galvanostatic operation, the z inc deposition current efficiency in the charge transfer control regio n attains values up to 77.3%, whereas in the diffusion control region it decreases rapidly to values as low as 0.1%. When a potentiostatic m ode is used, less energy is required to deposit zinc, even at low curr ent efficiency. The results and possible problems for continuous react or operation under conditions of powder formation are identified and d iscussed using knowledge from other zinc industries such as electrowin ning, plating and batteries.