Highly Efficient Method to Recover Silver from Discarded Plasma Display Panels

Abstract

In an attempt to fully utilize discarded plasma display panel (PDP), a highly efficient method was developed to recover silver from PDP. Silver contained in the electrodes of PDP can be firstly extracted into a solution using nitric acid (HNO3) and ultrasound sonication. An optimum HNO3 concentration is determined to satisfy both the extraction efficiency and the working condition of the chrome-nickel steel container. Later in the process, NaCl is added into the purified extraction solution to obtain sediment mainly comprises of AgCl. Then the sediment is further purified and reduced into metallic silver using different sediment/Fe weight ratios at different temperatures. An optimal sediment/Fe weight ratio is determined, while the temperature is found to be irrelevant with the reduction efficiency. By implementing a series of simple but effective purification methods, silver with a high purity of 99.43 wt% can be obtained. This method has been successfully applied in a silver recovery factory in Mianyang city, China for nearly two years, and has proved to be economically viable and environmentally beneficial.