Environmentally Sound Recovery of Gold from Waste Electrical and Electronic Equipment Using Organic Aqua Regia

Abstract

We conducted experiments using unit processes to prove the feasibility of the concept of an environmentally sound Au recovery process from waste electrical and electronic equipment (WEEE) using organic aqua regia, i.e., a propylene carbonate (PC) solution containing CuBr2 and KBr. First, the WEEE samples (memory card and mobile phone board) were finely ground. The samples were then carbonized and oxidized to decompose the polymers and oxidize the base metals. The leaching of Au from the oxidized samples was then carried out in a PC solution with 0.2 M of CuBr2 and 0.2 M of KBr over 353–373 K, followed by biphasic separation with sulfuric acid. The dissolved Au in the PC phase was recovered via ascorbic acid reduction. The mass balance of Au in the leaching was investigated. The maximum recovery ratios of Au from the memory card and mobile phone board were 79% and 83%, respectively. The cost of leaching was preliminarily estimated.