Extraction and Recycling of Dissolved Nickel from Ferric Chloride Etchant: Economic, Technical and Environmental Considerations

Emeritus Professor of Microengineering, Cranfield University, UK This paper was presented at the PCMI Conference, Chantilly, France on 20th May 2019 As nickel-containing metals are dissolved into ferric chloride etchant, the concentration of nickel ion builds up in solution even when the etchant is being regenerated. Above a critical dissolved nickel concentration, an unacceptable rough surface finish will become apparent in any half-etch areas of parts leading to product rejection and increased costs. It is therefore vital to control this build-up. Extraction of dissolved nickel from the etchant will extend its lifetime and the excess spent etchant can be utilised in environment-friendly recycling processes rather than disposal by landfilling. Furthermore, nickel is a costly metal and, if it could be reclaimed economically from spent ferric chloride waste, it would provide a cost reduction for the PCM process. This paper reviews the technology that will enable the extraction of dissolved nickel from spent ferric chloride etchant and considers the environmental and economic benefits that could accrue from such processes.