A Laboratory Study of Electrochemical Removal of Noble Elements from Secondary Aluminium

At present, recycled aluminium is "diluted" by primary metal to keep the impurity concentrations at acceptable levels. Future increase in recycling will require a new process for efficient removal of all impurities, including noble elements, from secondary aluminium. In the current preliminary laboratory study, an electrochemical method based on the well-known three-layer refining cell was explored. Metal with purity comparable to primary metal could be obtained from highly alloyed scrap feeds containing elements more noble than aluminium, such as iron, copper, manganese, and zinc. The energy consumption was as low as 8.5 kWh/kg Al, indicating that the process can be expected to be less expensive than for production of primary metal, but with higher costs than re-melting.