Recovery of Valuable Metals from Copper Tailings of the III and IV Regions of Chile, through Leaching Processes and the Use of Surfactants ^†

Chile is the world leader in the production of copper. It has the largest stock of copper, with almost 21% of worldwide reserves. Chilean mining exports accounted for 5.4 million MT in 2023, representing more than half of the national export value. Chile’s production accounted for 30 percent of the global production in 2023. Chile’s national massive mine cadaster shows that the mining industry generated 758 tailing deposits from copper mining operations located in ten regions. They account for 26.3 billion of authorized tonnes of mine tailings. The general geochemical registry of tailing deposits in Chile consists of rock forming minerals, like SiO₂ and Fe₂O₃, and trace elements. The primary goal of any remediation project for mining residues is the recovery of valuable metals, and in this case, Cu and Fe for the Chilean ores. The most difficult task involved in tailing reprocessing is the chemical dissolution of the ores into an aqueous solution, because of the refractory nature of the sulfides against acids. Several attempts have been made to recover valuable metals, proposing possible improvements to be used on the leaching techniques, but none of them have been successful until now. For this reason, we propose to improve the leaching process using surfactant agents to improve the hydrophilicity of mineral and tailing surfaces, by using hydrophilic groups in the leaching of sulfide ores. This will improve the surface wettability of minerals, and enhance the leaching effects.