Akvaplan-niva AS, Fram Centre - High North Research Centre for Climate and the Environment, Hjalmar Johansens Gate 14, 9007, Tromsø, Norway. Electronic address: kristine.pedersen@akvaplan.niva.no.
Repparfjorden in northern Norway has been partly designated for submarine mine tailings disposal when the adjacent Cu mine re-opens in 2019. In order to increase sedimentation, the flocculant, Magnafloc10 is planned to be added to the mine tailings prior to discharge into the fjord. This study investigated the feasibility of reducing the Cu concentrations (375?mg/kg) in the mine tailings by applying electrodialytic extraction, including potential optimisation by adding Magnafloc10. In the acidic electrodialytic treatment (pH??12), Magnafloc10 reduced the extraction of Cu from 17% to 0.7%, due to the flocs remaining in the tailing slurries. The electric energy consumption per extracted Cu was similar in the acidic and alkaline electrodialytic treatments without the addition of Magnafloc10. In the alkaline electrodialytic treatment, the extraction of other metals was low (