The environmental impact assessment of gold extraction processes for discarded computer RAM: a comparative study of two leaching chemicals

Electrical and electronic equipment waste (WEEE) problems should be set as a priority in Thailand due to unpleasant operations. E-waste mismanagement caused by illegal transport of WEEE has intensified public health and environmental concerns. Computers are processed in recycling industries, but they still contain vulnerable metal remnants, such as gold. High-grade components, such as Random-Access Module (RAM), for example, are often extracted by hydrometallurgical processes through different leaching chemicals along with their related methods. Gold leaching agents, including aqua regia and cyanide-based solutions, were considered to extract gold from computer RAM in this study. Environmental impacts of the two extracting processes were investigated using material flow analysis and life cycle assessment, based on 1 kg of recovered gold. The effect of pulp density was also measured. The comparison between the two leaching processes without waste management demonstrated that the cyanide-based solution provided 8.5 times lower in terrestrial ecotoxicity and 6.4 times lower in human carcinogenic toxicity than aqua regia due to the lower overall chemical consumption. Nevertheless, proper wastewater treatments and a combination of incineration and landfill for solid waste treatment are potential options to minimize these impacts.