Carbon footprint of gold recovery from refractory ore in Russia
Kasymova, Diana (2019)
Diplomityö
Kasymova, Diana
2019
School of Energy Systems, Ympäristötekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2019090226409
https://urn.fi/URN:NBN:fi-fe2019090226409
Tiivistelmä
With the increasing concern about sustainable gold mining, there is an urgent need to reduce greenhouse gas (GHG) emissions which come from various stages of gold ore processing. The amount of GHGs from gold production sector significantly varies depending on the type of raw material treated. Thus, share of GHG emission coming from low-grade refractory gold processing is already 50% more than that from free-milling ores processing. In the time of steady depletion of mineral resources, the percentage of low-grade ores in gold deposits is growing, thus making companies to develop new or improve existing methods for gold recovery. Enhancing gold production from refractory ore will undoubtedly lead to increase in GHG emissions in this sector, so that the paths for reducing GHG must be developed.
This Master’s thesis represents the carbon footprint (CFP) assessment of gold recovery from refractory ore in one of the leading countries in gold production – Russia, considering different pre-processing routes. CFP quantification allows understanding where the major environmental loads come from and facilitates action to decrease GHG emissions and enhance GHG removals throughout the life cycle of a product. The study was performed in accordance with ISO 14067: 2018 and ISO 14040: 2006 standards, utilizing life cycle assessment (LCA) approach. A model for assessment was created in GaBi (version 8.17.0.18) software. Gold production from sulfide refractory ore in Russia was examined, considering different treatment routes utilized by main gold producers in the country. Results of the CFP study have shown that the major contribution to GHG emission in current situation in Russia origins from transportation (52%), electricity production (20%), oxygen production (11%) and production of heavy fuel oil for maritime transportation (7%).
Analysis of alternative processing routes have shown that the lowest environmental impact is caused by implementing oxidative roasting technology. However, the results depend on the assumptions made for the study. Thus, it was assumed that roasting plant is equipped with a gas-cleaning system which allows safe recovery of gaseous compounds produced during oxidation reactions, ore contains 17% of sulfide sulfur and does not contain organic carbon, and the gold recovery rate by subsequent cyanide-leaching is 95%. It was found that the main possible paths to reduce environmental impact of refractory ore processing in Russia is to decrease transportation load by developing more advanced logistics system or considering alternative fuel for trucks and ships, decrease energy consumption or improve existing electricity production, and reduce consumption of reagents. It was concluded that other impact categories should be also assessed for more precise estimation of potential environmental load to select most appropriate route for gold production from refractory ore in Russia.
This Master’s thesis represents the carbon footprint (CFP) assessment of gold recovery from refractory ore in one of the leading countries in gold production – Russia, considering different pre-processing routes. CFP quantification allows understanding where the major environmental loads come from and facilitates action to decrease GHG emissions and enhance GHG removals throughout the life cycle of a product. The study was performed in accordance with ISO 14067: 2018 and ISO 14040: 2006 standards, utilizing life cycle assessment (LCA) approach. A model for assessment was created in GaBi (version 8.17.0.18) software. Gold production from sulfide refractory ore in Russia was examined, considering different treatment routes utilized by main gold producers in the country. Results of the CFP study have shown that the major contribution to GHG emission in current situation in Russia origins from transportation (52%), electricity production (20%), oxygen production (11%) and production of heavy fuel oil for maritime transportation (7%).
Analysis of alternative processing routes have shown that the lowest environmental impact is caused by implementing oxidative roasting technology. However, the results depend on the assumptions made for the study. Thus, it was assumed that roasting plant is equipped with a gas-cleaning system which allows safe recovery of gaseous compounds produced during oxidation reactions, ore contains 17% of sulfide sulfur and does not contain organic carbon, and the gold recovery rate by subsequent cyanide-leaching is 95%. It was found that the main possible paths to reduce environmental impact of refractory ore processing in Russia is to decrease transportation load by developing more advanced logistics system or considering alternative fuel for trucks and ships, decrease energy consumption or improve existing electricity production, and reduce consumption of reagents. It was concluded that other impact categories should be also assessed for more precise estimation of potential environmental load to select most appropriate route for gold production from refractory ore in Russia.