TY - JOUR
T1 - Process simulation based life cycle assessment of cyanide-free refractory gold concentrate processing – Case study
T2 - Cupric chloride leaching
AU - Elomaa, Heini
AU - Rintala, Lotta
AU - Aromaa, Jari
AU - Lundström, Mari
N1 - Funding Information:
The authors would like to thank the Emil Aaltonen Foundation for its financial support of the Sustainable Gold project. Additionally, this research is supported by the Finnish Foundation for Technology Promotion and GoldTail (grant nr. 319691 ), funded by the Academy of Finland, and is gratefully acknowledged. We would also like to thank Maria Leikola, D.Sc.(Tech), for her valuable comments and discussions.
Funding Information:
The authors would like to thank the Emil Aaltonen Foundation for its financial support of the Sustainable Gold project. Additionally, this research is supported by the Finnish Foundation for Technology Promotion and GoldTail (grant nr. 319691), funded by the Academy of Finland, and is gratefully acknowledged. We would also like to thank Maria Leikola, D.Sc.(Tech), for her valuable comments and discussions.
Publisher Copyright:
© 2020 The Authors
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/10/1
Y1 - 2020/10/1
N2 - The development of cyanide-free gold leaching methods is becoming increasingly important due to the treatment of complex ores, where treatment by cyanidation is not economically viable. Cupric chloride leaching provides an alternative leaching process to replace cyanidation. A detailed simulation of refractory gold concentrate processing by cupric chloride leaching is presented in this study. The simulation with mass and energy balances was built to be used as life cycle inventory data to evaluate the environmental impacts of the development stage cupric chloride process. Three cases, the Base Case (125 g/L Cl-), Mild Case (50 g/L Cl-), and Extremely Mild Case (20 g/L Cl-), were investigated in two flowsheet options. Loss of gold to wash waters was observed in the Flowsheet 1 cases, and therefore Flowsheet 2, with the recirculation of wash water to solvent extraction, was developed and investigated in order to achieve higher gold recovery. The gold extraction improved from around 85% to 99%. Chemical consumption (NaCl, NaBr, CuCl2) was greatly affected by the leaching conditions, higher concentrations consuming more initial chemicals. In milder conditions, efficient recycling of chlorides could be obtained in the process, and no addition of NaCl was required. In the Extremely Mild Case, the chloride concentration was close to sea water conditions (20 g/L), where sea water could be used to provide chlorides for the process, and the effluent waters could be disposed of in the sea after purification. The global warming potential was estimated to be 12.5 t CO2-e/kg Au in chloride leaching and was further decreased to 10.6 t CO2-e/kg Au in the mildest conditions (20 g/L Cl-). The milder chloride leaching conditions (20 g/L Cl- and 50 g/L Cl-) were shown to decrease the acidification potential, eutrophication potential, and water depletion.
AB - The development of cyanide-free gold leaching methods is becoming increasingly important due to the treatment of complex ores, where treatment by cyanidation is not economically viable. Cupric chloride leaching provides an alternative leaching process to replace cyanidation. A detailed simulation of refractory gold concentrate processing by cupric chloride leaching is presented in this study. The simulation with mass and energy balances was built to be used as life cycle inventory data to evaluate the environmental impacts of the development stage cupric chloride process. Three cases, the Base Case (125 g/L Cl-), Mild Case (50 g/L Cl-), and Extremely Mild Case (20 g/L Cl-), were investigated in two flowsheet options. Loss of gold to wash waters was observed in the Flowsheet 1 cases, and therefore Flowsheet 2, with the recirculation of wash water to solvent extraction, was developed and investigated in order to achieve higher gold recovery. The gold extraction improved from around 85% to 99%. Chemical consumption (NaCl, NaBr, CuCl2) was greatly affected by the leaching conditions, higher concentrations consuming more initial chemicals. In milder conditions, efficient recycling of chlorides could be obtained in the process, and no addition of NaCl was required. In the Extremely Mild Case, the chloride concentration was close to sea water conditions (20 g/L), where sea water could be used to provide chlorides for the process, and the effluent waters could be disposed of in the sea after purification. The global warming potential was estimated to be 12.5 t CO2-e/kg Au in chloride leaching and was further decreased to 10.6 t CO2-e/kg Au in the mildest conditions (20 g/L Cl-). The milder chloride leaching conditions (20 g/L Cl- and 50 g/L Cl-) were shown to decrease the acidification potential, eutrophication potential, and water depletion.
KW - CuCl
KW - Cyanide-free
KW - Gold leaching
KW - HSC-Sim
KW - Sustainable gold processing
UR - http://www.scopus.com/inward/record.url?scp=85088640730&partnerID=8YFLogxK
U2 - 10.1016/j.mineng.2020.106559
DO - 10.1016/j.mineng.2020.106559
M3 - Article
AN - SCOPUS:85088640730
VL - 157
JO - Minerals Engineering
JF - Minerals Engineering
SN - 0892-6875
M1 - 106559
ER -