Thiosulphate leaching of gold from waste mobile phone PCBs: Influence of key chemical agents on leaching behaviour
Main Article Content
Abstract
The Gold leaching from waste mobile phone printed circuit boards (PCBs) using an ammoniacal thiosulphate system was systematically investigated, with particular emphasis on the roles of dissolved oxygen, copper(II) ions, thiosulphate, and ammonia. Leaching experiments were conducted at 30 °C using dissolved oxygen and copper(II) ions acting as oxidants. The effects of reagent concentrations on gold dissolution kinetics were quantified using initial rate analysis. In the absence of Cu(II), the gold leaching rate exhibited an apparent reaction order of approximately 0.3 with respect to dissolved oxygen. Under oxygen-free conditions, reaction orders of 1.2, 0.38, and 0.32 were obtained for thiosulphate, Cu(II), and ammonia, respectively. A maximum gold dissolution of 98% within 10 min was achieved using a solution containing 60 mM thiosulphate, 10 mM Cu(II), and 0.26 M ammonia. Surface and phase characterisation by scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed complete gold removal under optimal conditions. The results provide a coherent basis for optimising thiosulphate-based gold recovery from waste mobile phones.
Keywords
Gold, Thiosulphate leaching, Printed circuit boards, Electronic waste, Recycling
Article Details
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