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Assessment of gold recovery processes in Bangalore, India and evaluation of an alternative recycling path for printed wiring boards

TitleAssessment of gold recovery processes in Bangalore, India and evaluation of an alternative recycling path for printed wiring boards
Publication TypeThesis
Year of Publication2006
AuthorsKeller M
Academic DepartmentInstitute for Spatial and Landscape Planning, Regional Resource Management ; Empa, Technology and Society Lab
Number of Pages105
UniversitySwiss Federal Institute of Technology (ETH), Materials Science and Technology Research Institute (Empa)
CityZurich & St.Gallen/ Switzerland
Thesis TypeMaster Thesis
AbstractRecycling of e-waste respectively of PWB is an ambiguous issue. On the one hand, precious metals can be recovered; on the other hand, environmental damages are caused during the recycling processes. The encountered recycling management system in Bangalore bears several problematic processes. One of the identified problematic processes by Rochat (2006) is the precious metal recovery. For example to recover gold from e-waste wet chemical leaching processes, which use several hazardous substances and materials (e.g. cyanide and nitric acid) are conducted. Scientific base data about these processes are barely available. Therefore, the focus of this thesis is to provide scientific background knowledge about gold recovery processes. In addition, an alternative pathway for the recycling of e-waste-, respectively of printed wiring boards (PWB) is evaluated. Using the methodology of material flow analysis (MFA) the used substances and materials of three different gold recovery techniques could be identified and partly quantified. Based on these results environmental impacts of the processes are qualitatively evaluated. The environmental contamination caused by the conducted processes in Bangalore is severe. The released toxic substances and heavy metals are high concentrated and most of them have the potential to accumulate in organisms and environment. In the effluent of a conducted gold recovery technique in an informal facility in Bangalore, metal concentrations, which are 5 to 370 times higher than the maximum permissible value in Switzerland, were detected. The solid waste from the processes, end up in the solid waste stream of Bangalore. This means that the metals eventually leach out to the environment. Further, the efficiency of the PWB recycling processes in Bangalore could be determined making a substance flow analysis (SFA) of gold. This assessment revealed that the gold yields of the recycling systems are quite poor. The yields of the gold recovery techniques are approximately 50 %. The assessed alternative is a relocation of the PWB treatment to an industrial smelter in Belgium (Umicore Precious Metals Refining) which is equipped with best available technology. It could be shown that the economic profit is much higher if the material is sold to the industrial smelter. In addition, the emissions to the environment would decrease drastically if these fractions of e-waste were treated with the metallurgic technique, conducted in Belgium.
Keller_2006_ETH-Empa.pdf3.23 MB
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