Abstract
Metal content determination is one of the critical aspects of preparing electronic waste for metal recycling. In spite of the fact that end-of-life printed circuit boards are considered to be a secondary resource reservoir, no standard procedure exists for determining the total metal content in this heterogeneous multicomponent material containing plastics, metals, alloys and ceramics. We investigated the utilization of United States Environmental Protection Agency (US EPA) microwave acid digestion (Method 3052) and various modifications of this procedure for effective releasing of Cu, Fe, Ni, Pb and Zn from waste printed circuit boards (WPCBs) from mobile phones. The maximum contents of Cu (22.6 wt.%), Fe (5.0 wt.%), Ni (2.0 wt.%) and Zn (2.6 wt.%) were obtained using the standard (unmodified) US EPA 3052 digestion procedure, but the total digestion of PCB material was not achieved. The solid residue material after digestion by means of the US EPA 3052 method consisted predominantly of oxides (Ca, Mg and Al) and fluorides (Ca and Mg), and some particles contained minor amounts of Fe and Cu.
Highlights
Older mobile phones types typically consist of electronic circuitry, a printed circuit board (PCB), a liquid crystal display, a battery, a keypad and a plastic case [1]
The results indicate that the extension of digestion time, with the exception of Cu, does not influence the increase in content of elements in the solution after digestion, nor does it increase the effectivity of digestion
The presence of Ca, Mg, Cu and F may indicate the formation of stable insoluble fluorides as a result of the reaction with conc
Summary
Older mobile phones types typically consist of electronic circuitry, a printed circuit board (PCB), a liquid crystal display, a battery, a keypad and a plastic case [1]. The waste PCBs (WPCBs) are diverse and complex in terms of their type, size, shape, components and composition [2]. The elemental composition of PCBs varies depending on their type and applications [3]. These PCBs contain, in terms of weight, approximately 40% metals, 30% plastics or polymers, and 30% ceramics or refractory metal oxides [1,2,4,5,6]. Three main types of recyclable materials can be retrieved from
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