Recovery and refining of precious metals alloys by oxi-nitrogen leaching

In recent years the demand for gold and other precious metals has increased dramatically, insomuch as in the last decade gold prices have quintupled. In the contest of the lack of trust in the traditional financial market, recovery and refining of precious metals from e-waste, automotive catalysts, and scrap jewellery and waste generated by jewellery manufacture have become increasingly more important. Controlled recovery of precious metals reduces additional waste production and helps prevent the need for supplementary mining. Metal recovery and refining processes can also have adverse effects on the environment when not conducted properly, especially when the pressure of the precious metals market price makes the refining companies speed up production. Separation technology described here is the hydrometallurgical method whereby gold-bearing alloys are obtained from gold scraps and wastes. Different metal grades are refined by aqua-regia or nitric acid dissolution in the presence of oxi-nitrogen species.