Copper recovery from nickel laterite with high-iron content: A continuous process from mining waste

The waste product from the hydrometallurgical processing of nickel laterite ores can contain valuable metals, making their recovery economically viable. However, the high-impurities content, mainly iron, makes the process technically unfeasible. As a result, the separation of metals from the leach solution must be selective. Among the techniques available, the use of chelating resin is advantageous due to its selectivity and low energy consumption. Among the commercial chelating resins available, Dowex XUS 43605 has been shown to be highly selective for copper and can be used with a high impurities content. Although there are studies on the use of Dowex XUS 43605, none have evaluated a high impurities content and modelled a continuous process. For this reason, the aim of this work was to investigate copper recovery by a continuous process. The Dowex XUS 43605 chelating resin with HPPA functional group was used in ion-exchange experiments. Column experiments were performed in two steps: loading (to recover copper) and elution (to obtain a copper-rich solution). The removal of iron and the subsequent collection of copper were possible in a precipitation step using CaCO3. The results showed that the solution obtained from elution had a copper concentration that was 10 times higher than in the loading. All of the iron was removed from the elution solution at pH 3.5 with 5% of copper losses. Copper precipitation was possible at pH 5.5. From the results obtained, a proposed flowsheet for recovering copper was suggested.