Recovery of copper, tin and lead from the spent nitric etching solutions of printed circuit board and regeneration of the etching solution

In order to recover valuable metals and regenerate the etching solution from the spent nitric etching solutions of printed circuit board (PCB), solvent extraction, stripping, electrowinning, precipitation and cementation experiments have been performed. Nitric acid was selectively extracted by TBP from the spent etching solution and pure nitric acid solution was stripped by distilled water. After extracting nitric acid, pure copper metal was obtained by electrowinning and tin ions were precipitated by adjusting the pH of solution with Pb(OH)2. Lead metal with purity of 99% was obtained by cementation with iron powder.