Acidic mine waters represent natural effluents from pyritic ore deposits and they are mainly characterized by a low pH and a high concentration of metal ions such as Fe3+, Zn2+, Cu2+, Mn2+, Al3+, Ca2+, Mg2+ and Na+. The treatment of these waters is of great economic and ecological importance. The present study was targeted at the development of a reagentless and wasteless dual-temperature ion-exchange technique for concentrating copper from the natural acidic mine waters of Rio Tinto area (Huelva, Spain). The carboxylic ion exchanger (Lewatit R 250-K) and iminodiacetic resin (Lewatit TP-207) were used. Values of the resin capacity towards mine water metal ions and the equilibrium separation factors (α) for different metal ion couples have been determined at different temperatures in the range 20-80°C. Acrylic resin has been found to be selective for Al3+ and iminodiacetic resin demonstrates high selectivity for Cu2+. Furthermore, the sorbability of Al3+ increases while that of Cu2+ decreases with temperature for both resins. This effect gives the possibility for a selective thermostripping of Cu2+ from the resins pre-equilibrated with cold mine water (at 20°C) using hot mine water at 80°C. The increase in the Cu2+ concentration in the eluate is 30% for acrylic resin and 20% for iminodiacetic resin. The concentration of Al3+ in the stripping solution drops to 50% in the first case and to 70% in the second.
|Publication status||Published - 1 Mar 1997|