Copper solvent extraction (SX) plants have seen a trend of increasing chloride content in their feed solutions due to shortage of fresh water (and use of sea water) and/or intentional addition of chloride to aid in the leaching process. The high chloride content of the pregnant leach solution (PLS) presents some challenges as it can affect the SX process with higher acidity, higher aqueous viscosity, and greater sensitivity to aqueous-in-organic (A/O) entrainment. Low pH and high viscosity of the PLS can impact the metallurgical performance (stage efficiency and Cu recovery). The sensitivity to A/O entrainment requires additional considerations such as optimization of the wash stage(s), use of coalescers, as well as monitoring and improving the physical quality of the organic phase. The following study presents the results of a complete review of the metallurgical behavior of the SX plant when utilizing PLS with high chloride content. The study reinforces the importance of maintaining a high organic quality through efficient clay treatment. It also demonstrates the advantages of using modified aldoximes (over ketoxime based formulations) to maintain extraction capacity at low pH, taking advantage of the faster kinetics to offset the drop in stage efficiency due to higher aqueous viscosity.
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