Electro-remediation of copper mine tailings. Comparing copper removal efficiencies for two tailings of different age

This work compares and evaluates the copper removal efficiency when applying electric fields to two mine tailings originating from the same mine but of different age. Eight experiments were carried out – four on tailings deposited more than 20 years ago (old tailings) and four on tailings deposited less than 2 years ago (new tailings). Parameters analyzed were the applied voltage drop, acid concentration during pretreatment, and the use of either passive or ion exchange membranes in the experimental setup.The comparison of the results confirms that there are differences in the electroremediation between the two tailings, even if the pH is similar and a mineralogical analysis showed similarities between the samples with respect to composition. It was found that an electroremediation is more favorable on the old tailings. The results showed that the best experimental conditions for both tailings is a pretreatment with H2SO4 1 M followed by applying 40 V for 7 days, using ion exchange membranes. In this case 16.7% of copper was removed from the anode section for the old tailings, whereas only 11.2% was removed from the new tailings. The current efficiencies with respect to copper for the old and new tailings were 1.7% and 1.6%, respectively.

► Electric fields mobilize copper in both old and new copper mine tailings.
► It is recommendable to remediate old tailings compared to new tailings.
► After EKR, remaining copper is mainly insoluble copper.
► EKR is less efficient, when calcite content is very high.