Value recovery from Mukondo mine low-grade cobalt ore by heap leaching and solvent extraction

Abstract: The study reports a method of processing a low-grade copper–cobalt oxidized ore by heap leaching and solvent extraction. Optimisation of heap leaching parameters was carried out by performing both stirred-tank and in-tray batch leaching tests. Based on the optimum conditions established, a semi-continuous heap leaching pilot plant was designed and run. The pregnant leach solution obtained yielded 2350 mg/L Cu, 3800 mg/L Co, 3600 mg/L Fe, 130 mg/L Mn, 25 mg/L Zn and 0.58 g/L of solids in suspension. The pH and acidity of the PLS were 1.27 and 3.66 g/L, respectively. Copper, cobalt and impurities (manganese and zinc) were successfully extracted using 30% v/v CP-150, 20% v/v IONQUEST 290 and 20% V/V D2EHPA, respectively. The overall recoveries of copper, cobalt and impurities were 98%, 99% and 70%, respectively. The purified copper and cobalt electrolytes obtained can be further treated by electrowinning or salt precipitation