Qualitative risk assessment and identification of key drivers for consideration during selection of a copper tailings disposal technology, A

Abstract

Technologies utilized for the disposal of slurry, paste, thickened, and filtered tailings include containment within impoundments, open pit backfill, submarine placement, underground backfill, tailings and waste rock combined disposal, and dry stack placement. Each technology has inherent environmental, social, and economic drivers to be considered during mine planning. Geotechnical and geochemical properties of the tailings, and site-specific design constraints will also drive the selection of a disposal technology. Alternative technologies should be developed to address the increase in volume of tailings generated as lower grade ore is extracted, and to minimize risk associated with current technologies. Understanding the key drivers for selection of existing technologies is a necessary precursor to the future development of alternative technologies. This thesis presents a qualitative risk assessment of environmental, social, economic, geotechnical, geochemical, and site-specific elements utilized in selection of a tailings disposal technology. United States regulations and international guidelines for tailings disposal, and general industry accepted goals for current disposal technologies are summarized. Copper deposit geology, ore processing methods and available disposal technologies are described. Results of the qualitative assessment include the identification of critical, high, moderate, and low ranked drivers for the selection of each tailings disposal technology. Critical and high ranked elements are recognized as key drivers for consideration during the selection of each tailings disposal technology. Key drivers for all technologies include the political and regulatory climate, investor confidence, and the acid generation and neutralization potential of the tailings. Key drivers for consideration during the selection of all surface disposal technologies also include land disturbance, construction cost, and the availability of local materials for construction. Understanding the key drivers for each disposal technology will assist the selection of a suitable, site-specific technology, and is a necessary precursor to the future development of alternative technologies.