AN ANALYSIS OF METAL RECOVERY BY ELECTRODEPOSITION FROM MIXED-METAL ION SOLUTIONS .1. THEORETICAL BEHAVIOR OF BATCH RECYCLE OPERATION

Electrodeposition offers a means of a single step recovery of the base metal from aqueous process or waste stream. With solutions of mixed metal ions this may not be an attractive proposition unless procedures are adopted to mask the influence of certain components which cause inefficiency in the selected single metal deposition and which may also be codeposited. This problem is considered here in the context of metal removal from a solution also containing a second dissolved metal in the form of ferric ions. A mathematical model is developed which describes the process of metal deposition from mixed metal ion solutions in batch recycle operation. The model is used to illustrate typical performance characteristics with the cell operating under either galvanostatic or potentiostatic conditions. The electropositive nature of Fe (III) in aqueous solution results in a major loss in metal deposition efficiency, and high rates of mass transport mainly affect the rate of deposition rather than the efficiency.