Evaluation of Copper Extraction on Low-Grade Oxide Ores Using Column Heap Leaching

Heap leaching is an economically viable hydrometallurgical technique extensively employed in the mining industry for extracting valuable metals such as copper from low-grade ore deposits. This method renders a cost-effective solution for processing ore that would otherwise be considered uneconomical for conventional extraction techniques. This study investigates the efficiency of copper recovery from different particle size fractions of low-grade oxide ores that have undergone crushing stage. Hydrochloric acid was used as a lixiviant in column heap leaching experiments to study the effect of particle size on copper extraction recovery. The experiments were conducted using column leach setups with dimensions of 150 mm in diameter and 2 meters in height. Crushed ore samples, ranging in particle size from 25 mm down to 1.8 mm, were divided into 5 kg aliquots and loaded into the columns, with a total mass of approximately 40 kg per test. Leaching was performed over a period of 16 days using an acid concentration of 200 g/L. The results demonstrated promising copper recoveries. One sample achieved a copper extraction rate of 75% within 16 days, with maximum acid consumption reaching 23 kg/ton over 15 days. Another sample yielded a comparable copper recovery of 74% under the same timeframe but required a higher acid consumption rate of 30 kg/ton. Moreover, the consistent linear increase in copper recovery throughout the leaching period suggests minimal interference from pregnant solution robbing impurities in the ore that consumes the lixiviant.