Metal Extraction Processes for Electronic Waste and Existing Industrial Routes: A Review and Australian Perspective

Abstract

The useful life of electrical and electronic equipment (EEE) has been shortened as a consequence of the advancement in technology and change in consumer patterns. This has resulted in the generation of large quantities of electronic waste (e-waste) that needs to be managed. The handling of e-waste including combustion in incinerators, disposing in landfill or exporting overseas is no longer permitted due to environmental pollution and global legislations. Additionally, the presence of precious metals (PMs) makes e-waste recycling attractive economically. In this paper, current metallurgical processes for the extraction of metals from e-waste, including existing industrial routes, are reviewed. In the first part of this paper, the definition, composition and classifications of e-wastes are described. In the second part, separation of metals from e-waste using mechanical processing, hydrometallurgical and pyrometallurgical routes are critically analyzed. Pyrometallurgical routes are comparatively economical and eco-efficient if the hazardous emissions are controlled. Currently, pyrometallurgical routes are used initially for the segregation and upgrading of PMs (gold and silver) into base metals (BMs) (copper, lead and nickel) and followed by hydrometallurgical and electrometallurgical processing for the recovery of pure base and PMs. For the recycling of e-waste in Australia, challenges such as collection, transportation, liberation of metal fractions, and installation of integrated smelting and refining facilities are identified.

Evaluation of Wet Digestion Methods for Quantification of Metal Content in Electronic Scrap Material

“…Figure 5 shows that pre-treatment significantly increased the metal recovery efficiency of several metals (Ag by 10%, Al by 15%, Au by 8%, Cu by 13%, Fe by 10%, Ni by 15) (p < 0.05). Ashing pre-treatment removed the volatile matter in the ESM solid matrix, and resulted in a concentration of trace metals and an increase in the oxidation state of the metals, and thus enhanced the solubilization of the metals by acids in the subsequent step [22,41]. Figure 5.…”

“Control-Alt-Delete”: Rebooting Solutions for the E-Waste Problem

“…119,120 In the developed nations, the options available for e-waste management are recycling and recovery of materials and components from defunct products for use in making new similar (closed-loop recycling) or different (open-loop recycling) products; or incineration and landfilling, which are increasingly rare because of legislation. 121 In developing countries, the collection of ewaste from consumers remains a major impediment against the development of coherent and sustainable management practices that minimize adverse environmental impacts. The differences in the national development of e-waste recycling industry can be attributed to a lag in technology transfer, high cost of necessary equipment and maintenance, capacity of facilities, and paucity of skilled labor.…”

E-Waste Supply Chain in Mexico: Challenges and Opportunities for Sustainable Management

“…Among the heavy metals included in WEEE we can find mercury, lead, cadmium, and chromium, halogenated substances, such as chlorofluorocarbons (CFCs), chlorinated biphenyls (PCBs), and polyvinyl chloride (PVC), as well as some flame retardants. Therefore, it is important to evaluate the risks and make integral e-waste management strategies [37,38].…”