Mine Tailings Reprocessing and Repurposing with Mineral Processing and Extractive Metallurgy

Global mining companies are paying a significant amount of money for maintaining and operating tailings storage facilities. The amount of economic and environmental impacts can be innumerable when catastrophic failures happen. Due to the issues on access, stability of dam structures, battery limitations, and potential toxicity, it is difficult to access and reprocess tailings. Copper mine tailings from an active mine were used. Copper content in the tails varied from 0.06% to 0.08% with relatively high sulfide sulfur content mainly from pyrite. The value of copper was extremely low, but the potential for acid mine drainage is high. Other metals with interest in tailings are arsenic, nickel, and cobalt with very low concentrations. Conventional flotation for pyrite was used to produce sulfide concentrates. All metals associated with pyrite and other sulfides were concentrated with 50% sulfide sulfur content. The concentrates were biooxidized with a mixture of mesophilic microorganisms. Metal extraction, particularly base metals such as copper, nickel, and cobalt, were high between 60 and 80%. The cleaner leached residues and flotation tails were combined to produce Geofoam that can be used as thermal insulating material, concrete alternatives, cement clinker replacement, and materials for 3D printing. A pilot scale testwork has been completed successfully and onsite trial with modular units will soon follow. The overall process and economic evaluation of the project will be discussed with metal recovery, fabrication of value-added products, and CO₂ sequestration from tailing repurposing process.