A Study on the Separation of Cadmium from Waste Ni-Cd Secondary Batteries by Ion Substitution Reaction

In order to recycle waste nickel-cadmium batteries, cadmium was selectively removed by ion substitution reaction so that cadmium and nickel could be separated efficiently. The electrode powder obtained by crushing the electrode in the waste nickelcadmium battery was leached with sulfuric acid. The cadmium in the nickel-cadmium solution was precipitated with cadmium sulfide by the addition of sodium sulfide. Ion substitution experiments were carried out under various conditions. At the optimum condition with pH = −0.1 and Na2S/Cd = 2.3 at room temperature, the residual Cd in the solution was about 100 ppm, and most of it was precipitated with CdS.