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Investigation of the Attenuation and Release of Cu2+ Ions by Polymer-Treated Tailings

This study investigated the attenuation and release behaviour of copper ions using a standard kaolin-silt slurry as the synthetic tailings in a high solids/high salinity application before and after inline flocculation. A homogenous, synthetic tailings slurry was prepared in a 0.6 M NaCl solution and treated in a low-shear mixer by adding Magnafloc® 336 flocculant. Following the evaluation of morphological properties of both the untreated (UT) and polymer-treated tailings (PT), identical equilibrium tests were performed via the bottle-point method constant concentration technique. The maximum copper ions uptake capacity of polymer-treated tailings was 25% more than the untreated slurry at the equilibrium state in a chemisorption process in which the ions had the capability of binding onto one location on the sorbent, which could be influencing other binding sites on the same sorbent. Polymer treatment resulted in a highly porous structure that exhibited an increased capacity to adsorb and retain copper ions compared to the UT materials. This behaviour indicates the strong binding between the copper ions and active site of the treated tailings particles with greater capability of this material for preserving heavy metal ions within their structure across a wide pH range (2–10) compared to the UT materials. The results advance the fundamental understanding of how inline flocculation can considerably improve the sorption capacity of high solids/high salinity tailings favouring potential long-term rehabilitation purposes at mine closure and the role of sorption and desorption of heavy metal ions’ behaviour play to achieve this goal.