Investigation of Affecting Parameters on Heap Leaching Performance and Reducing Acid Consumption of Low Grade Oxide-Sulfide Copper Ore

Heap leaching method is known as a cost-effective approach for copper extraction; however, the presence of clay and acid-consuming waste minerals critically impacts the economic feasibility of the process. This study aimed to reduce acid consumption and enhance copper extraction from low-grade oxide-sulfide copper ore by conducting systematic tests. Approximately three tons of sample were collected from various low-grade zones, followed by homogenization and preparation for bottle roll tests aimed at optimizing copper recovery and acid consumption at pH levels of 1, 1.1, and 1.2. The maximum copper recoveries recorded were 60.8%, 60.2%, and 60.1%, with corresponding acid consumptions of 107.30, 99.90, and 93.23 kg/t of ore. Nine columns were set up with varying dimensions and filled with ore of different sizes, and these were subjected to various concentrations of acid solutions over a 63-day irrigation period. Results indicated that there is a strong correlation between copper and iron recoveries, with copper recovery varying from 25.5% to 58.9% as iron recovery shifted from 4.7% to 15.2%. The findings underscore that while longer leaching periods increase copper extraction, they also amplify acid waste, emphasizing the pivotal roles of acid concentration and irrigation flow rate in influencing recoveries.