Photoetching of nickel alloys and reclamation of waste products

This thesis details a study into the photoetching of nickel alloys with ferric chloride and the reclamation of waste products. Reclamation occurs through the regeneration of the spent etchant and the recovery of the dissolved nickel content. Etchant regeneration is a means by which a constant etching quality can be maintained. The alternative is its replacement with fresh solution and this option entails the disposal of the exhausted solution according to correct legislative procedures. A cost comparison of both processes, was made in the early stage of this work and a model established to represent the economics of regeneration and conventional disposal (ie. not regenerating) based on the amount of nickel etched per annum. Although the dissolved nickel content will not hinder etchant regeneration, it will affect the quality of subsequent etching and the etchant will remain "contaminated". Consequently, its removal must be considered if etchant regeneration is to be implemented. Therefore, in order to establish the economical viability of nickel removal (and etchant regeneration) it was necessary to investigate potential techniques at an experimental level and to determine their technical feasibility first. Cementation and electrodialysis were investigated, the latter proving to be the more successful technique for this application. Through experimentation, it was possible to determine nickel yield data and the associated chemical and power requirements. This information was then used to calculate the 'costs associated with the process in order to extend the original model.