Recycle Technology for Recovering Resources and Products from Waste Printed Circuit Boards

Abstract

The printed circuit board (PCB) contains nearly 28% metals that are abundant non-ferrous metals such as Cu, Al, Sn, etc. The purity of precious metals in PCBs is more than 10 times higher than that of rich-content minerals. Therefore, recycling of PCBs is an important subject not only from the treatment of waste but also from the recovery of valuable materials. Chemical and mechanical methods are two traditional recycling processes for waste PCBs. However, the prospect of chemical methods will be limited since the emission of toxic liquid or gas brings secondary pollution to the environment during the process. Mechanical processes, such as shape separation, jigging, density-based separation, and electrostatic separation have been widely utilized in the recycling industry. But, recycling of waste PCBs is only beginning. In this study, a total of 400 kg of waste PCBs was processed by a recycle technology without negative impact to the environment. The technology contained mechanical two-step crushing, corona electrostatic separating, and recovery. The results indicated that (i) two-step crushing was an effect process to strip metals from base plates completely; (ii) the size of particles between 0.6 and 1.2 mm was suitable for corona electrostatic separating during industrial application; and (iii) the nonmetal of waste PCBs attained 80% weight of a kind of nonmetallic plate that expanded the applying prospect of waste nonmetallic materials.

Use of scalp hair as indicator of human exposure to heavy metals in an electronic waste recycling area

“…Although most countries have ratified the Basel Convention, which strictly controls the transboundary movements of hazardous wastes (including e-wastes), unregulated and even illegal export of e-waste still takes place to transition or developing countries such as China, India and Nigeria (United Nations Environment Programme, 2005). In these countries, rudimentary processes such as open burning and acid stripping, which are common practices to recover valuable compounds in e-waste, often result in the release of high levels of organic pollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and toxic heavy metals such as Pb, Cd, Cr, and Cu (Basel Action Network, 2002;Deng et al, 2006;Gullett et al, 2007;Leung et al, 2007;Li et al, 2007). Besides obvious health implications for the dismantling workers, the pollutants can also contaminate the surrounding environment and further be transported to other areas adjacent to the recycling centers, such as rice fields (Fu et al, 2008), soils (Leung et al, 2006), and rivers and sediment (Wong et al, 2007b).…”

Kinetics of tetrabromobisphenol A (TBBPA) reactions with H2SO4, HNO3 and HCl: Implication for hydrometallurgy of electronic wastes

“…Recycling of valuable metals from electronic wastes (e-wastes) has been of worldwide concern [1]. There are three technologies currently available for recovering metals from e-wastes: mechanical/physical, pyrometallurgical, and hydrometallurgical processes [2].…”

Electronic Waste Disassembly with Industrial Waste Heat

“…In addition, precious metals, such as Au, Ag, and Pd, which were used as contact materials or plating layers because of their electric conductivity and chemical stability, 3 are 10 times more abundant in e-waste than in natural ores. 4 This has led to the proliferation of artisanal e-waste mining in unregulated cottage industries, especially in developing countries. Such artisanal mining processes contribute to the exposure of workers, nearby residents, and ecosystems to toxic metals and halogenated flame retardant chemicals, with devastating consequences to health and environmental quality.…”