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Environmental impact assessment of gold production from different types of ore in Nevada
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Kadivar_unr_0139M_14185.pdf
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Kadivar_unr_0139M_14185.pdf
Date
2023Type
ThesisDepartment
Metalurgical Engineering
Degree Level
Master's Degree
Abstract
The available supply of high-grade gold ore has significantly decreased, and there is growing concern about sustainable gold mining. Despite the strict environmental management regulations, various methods of gold mining can affect the ecosystem and human health since gold mining is an energy-intensive process and discharge substantial quantities of chemicals combined into the environment and gaseous emissions into the atmosphere. Therefore, there is an urgent need to assess the environmental sustainability of producing gold from different types of ore, including refractory, double refractory, or low-grade oxidic ore. This study used a life cycle assessment (LCA) approach to evaluate the environmental burdens associated with gold production from various types of ore that used appropriate processes, including roasting, autoclave or pressure oxidation followed by flotation, and heap leaching. Considering various stages and treatment routes utilized by the gold producers in Nevada, categories of ozone depletion, global warming, smog, carcinogenics, non-carcinogenics, respiratory effects, and fossil fuel depletion were evaluated Using the TRACI method. LCA results of this study showed more significant environmental impacts for processing refractory ores in almost all the impact categories except acidification. The potential climate change for processing refractory ore using autoclave and flotation was 1.75E+04 CO2-equiv, while it was 1.17E+04 CO2-equiv and 6.75E+02 CO2-equiv for roasting and heap leaching process, respectively. The higher environmental footprint related to SO2 emissions (acidification) in roasting was mainly due to the direct emissions containing sulfur compounds. The high value of electricity consumption and substantial gaseous emissions made the grinding stage the dominant contributor in almost all the impact categories for refractory and double refractory ores. No grinding was required for processing low-grade oxidic ore, and the contribution of crushing to overall global warming was insignificant. However, the contribution of grinding to the overall global warming in roasting and autoclave processes was significant and reported at 34.8% and 39.4%, respectively. This indicates that these stages need more attention and actions toward environmental regulations by using green electricity sources and additional treatment processes to achieve the goal of GHG emissions reduction. This study's results can be used as a comprehensive resource by stakeholders to compare the effects of gold mining activities and make better environmental decisions.
Permanent link
http://hdl.handle.net/11714/10586Additional Information
Committee Member | Chu, Pengbo; Vasquez, Victor; Akbari, Hamid |
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