Recycling of the impure tin generated by the hot dip tinning and wave soldering technologies widely applied in modern electronic industry can be carried in a flexible and economical way even at relatively low production rates by electrorefining. In order to avoid the economical disadvantages of the alkali stannate or the sulphuric acid – cresylic phenylic sulphonic acid baths, the hydrochloric acid tin chloride electrolyte solutions can be applied. The major difficulties of solution stability, cathode corrosion and rough electro-crystallization can be overcome by optimizing the solution composition and the current parameters. Strong chloro – complex formation in the hydrochloric acid solution enhance stability of the Sn(II) species and the consequent natural inhibition promotes a cathodic deposition of acceptable quality. The virtual current efficiency and the morphology of electro-crystallization were improved by applying periodically reversed (PCR) current. Although cathode corrosion could be depressed to a negligible level, dendritic crystal growth remains to be dominant, therefore special cell arrangement and cathode handling should be applied. The cathode deposit is easily removed and melted, allowing to obtain a recycled tin of high purity.
Discussion(0)
No comments yet. Be the first to comment.