On the Investigation of the Thermal Degradation of Waste Printed Circuit Boards for Recycling Applications

Abstract

becoming obsolete, especially in electronic devices. In fact, these types of valuable metal concentrations are such that electronic wastes can nowadays be considered as urban mines that need to be exploited. Urban mining is a concept that is emerging in our modern society. According to the United Nations Environment Programme (UNEP), around 20-50 million metric tons of waste electrical and electronic equipment (WEEE) are generated worldwide each year from which approximately 8.9 million metric tons are collected and recycled (about 20%) whereas 1.7 million metric tons are dumped into landfill and incinerated in different countries. [1][2][3][4][5] Direct combustion and landfill are considered the worst handling techniques of WEEE but are still common practices in countries that have no effective regulations or lack of necessary facilities for waste management. [6][7][8] Waste printed circuit boards (WPCBs) are basic non-conductive structures on which different electronic components are layed and electrically connected via conductive materials. As can be seen from Table 1, a standard WPCB consists mostly of:

Greener reactants, renewable energies and environmental impact mitigation strategies in pyrometallurgical processes: A review

“…Other valuable metals are also being recovered from other waste streams via pyrometallurgical operations: this includes cadmium and nickel recovered from rechargeable batteries via smelting processes, 161 aluminum recovery from cans and aluminum foil via remelting in rotary furnaces and many other valuable metals (such as Cr, 162 Cu, 163 Ni 164 ) from slag carbo-reduction in high-temperature furnaces among others. Important challenges associated with the integration of these streams into conventional primary metal processes include the presence of polymers which may release toxic emissions at high temperature upon their combustion and thermal degradation (such as metallic bromide release upon heating electronic waste 165 ), the simultaneous presence of many metals (both noble and reactive metals) which need to be chemically separated 166 and the contamination by oil, paint and organic waste which may promote the unwanted presence of volatile elements such as hydrogen and sulfur along with the possible formation of carbides. 150 and Hosseini et al 151 There are three basic operations for the separation of valuable metals from impurities during recycling operations: i.e., oxidation, reduction and evaporation/condensation.…”

Effect of Microwave Pretreatment on the Leaching and Enrichment Effect of Copper in Waste Printed Circuit Boards

“…5,6 The abundance of these valuable elements is much higher than the natural abundance, 7 so it is important to promote the resource utilization of these "secondary resources" for environmental capacity and sustainable economic development. 8,9 At present, the common WPCB resource treatment methods include mechanical method, 10,11 chemical method, 12,13 incineration method, 14,15 pyrolysis method, 16,17 biological method, 18,19 and so forth. Regardless of the method, efficient extraction of metals is the key to resourceful treatment of WPCB.…”

“…At present, the common WPCB resource treatment methods include mechanical method, , chemical method, , incineration method, , pyrolysis method, , biological method, , and so forth. Regardless of the method, efficient extraction of metals is the key to resourceful treatment of WPCB.…”