Techniques to separate metal from waste printed circuit boards from discarded personal computers

Abstract

Waste printed circuit boards contain valuable metals such as Au, Pd, Ag, and Cu that can be reutilized and harmful elements such as Pb, Br, and Cr that must be removed from the viewpoint of environmental conservation. In this research, we examined a method that separates the materials from printed circuit boards contained in discarded personal computers. After cutting the printed circuit boards to a size of 20 × 20 mm, they were heated at 873 K under an Ar atmosphere to remove organic resins containing elements such as C, H, and N. After heat treatment, the printed circuit boards were crushed using a planetary ball mill and the pulverized powders were fi ltered. The fraction with a granularity of greater than 250 μm was separated into magnetic and nonmagnetic materials by a magnetic fi eld. Because the fraction with a granularity of less than 250 μm contained 39 mass% of C, it was heated at 1273 K in an atmosphere of 95% Ar and 5% O 2 to allow carbon combustion to take place, followed by metal reduction processing at the same temperature in an atmosphere of 97% Ar and 3% H 2 . The basicity of the resulting powder was adjusted and the powder was heated at 1773 K under an Ar atmosphere. The proposed method separated the slag and metal, and 80% of the valuable metals contained in printed circuit boards could be collected.

Delamination mechanism study of large size waste printed circuit boards by using dimethylacetamide

“…Once, end recycling is the precursor of the mechanical processing, high efficiency of metal recovery is registered, but the overall economy of the recycling of PCBs is compromised (Hino et al, 2009). Contrary, exclusion of mechanical processing leads to generation of toxic and carcinogenic gases (Alabi et al, 2012;Kahhat and Williams, 2012), high lixiviate consumption, large effluent generation and poor metal recovery yields (Havlik et al, 2010;Jha et al, 2012).…”

Electronic Waste Disassembly with Industrial Waste Heat

“…Approximately, one-third of the weight of WPCBAs consists of metals, mainly Cu, Sn, Fe, and Pb. 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.…”

Materials Separation from Pulverized Waste Printed Circuit Boards

“…The hydrometallurgy processing (6) needs the neutralizing of the oxidized gas and the waste fluid. In this study, we investigated the possibility of not only removal of the organic resin, but also magnetic separation of metals from pulverized PCB powder as a preliminary processing method of fusion processing (7) .…”