The Bureau of Mines developed a process using ion exchange to recover cobalt from spent copper leach solutions. A preliminary economic evaluation of the process indicated that about one-third of the capital cost was attributed to the total resin inventory, and one-third of the operating cost was required for reagents to remove iron from the ion-exchange eluates. An agitated pachuca elution system was investigated in place of a fixed-bed elution system. The pachuca system reduced the resin inventory by 27 pct when compared with the fixed-bed elution system. Processing fresh spent copper leach solution reduced the resin inventory by 20 pct and resin iron loading by 80 pct. Reagent requirements for removing iron from the eluates were decreased because less iron was extracted. The pachuca system, along with processing fresh spent copper leach solution, reduced the total resin inventory by 47 pct. A revised cost evaluation of the cobalt recovery process was obtained to determine the effects of these process modifications. The estimated total capital cost for a plant processing 10,000 gpm of spent copper leach solution containing 26 ppm CO was $23.1 million. With credits for nickel, zinc, and copper byproducts, the estimated net operating cost was $5.10/Lb of cobalt.