Acid Regulation for Wet Process in Industrial CopperRecovery from Ore Using Layered Double Hydroxides and the Mechanism

Aiming at the acid selection for the industrial process of copper ore decomposition and improvement of copper recovery, we investigated the influence of different acids on the Cu²⁺ adsorption capacity of CaAl-Cl-LDHs fabricated by a novel atomic economic route. As-prepared materials exhibited improved removal efficiency in SO₄^2– solution than in Cl^– and NO₃^– ones. It was found that dissolved Ca²⁺ from CaAl-Cl-LDHs easily reacted with SO₄^2– to form CaSO₄ precipitation, further promoting CaAl-Cl-LDHs decomposition, thereby driving higher Cu²⁺ removal via generation of not only CuAl-LDH but also basic copper sulfate. Therefore, sulfuric acid was selected in actual industrial processes of iron–copper ore to improve the recovery rate in smelting wastewater. CaAl-Cl-LDHs were further produced on a larger scale with a production line of 20000 tons/year, showing satisfactory removal efficiency (∼90%), copper-containing materials (11.4%), and reusability. This work provides a new method to select acids during wet processing for ores to improve the copper recovery rate.