The production of silver nano powder from electronic waste by hydrometallurgy with application in the automotive industry

The demand of silver is ever increasing with the advanced of the industrialized world, whereas worldwide reserves of high grade silver ores are isolation. Over 1000 tons of silver are used annually in motor vehicles. For example, every electrical connection in modern car is activated with silver-coated contacts. In this study, the processes of recovery and extraction of silver powder from one of its secondary sources, namely, electronic waste, are described. The silver recovery method is based on the leaching of keyboard Mylars by nitric acid solution, which investigated the effect of reaction time, acid concentration and pulp density (g/mL) on the efficiency of silver recovery. The results of the ICP-Mass analysis in this process showed that the recovery rate of silver is more than 95%. Also, in order to extract the silver powder from the leaching solution, the precipitation method was studied with the chloride compound, such as NaCl. In this step, pH value and precipitation time was investigated. Finally, to investigate the silver compounds, XRD analysis and also to investigate the morphology and size of extracted silver powder particles, SEM were used. The processes can be scaled up to small pilot plan.