Coupled Dissolution with Reprecipitation (CDR) Reactions and Their Impact on Copper Sulphide Mineral Surface Area and Dissolution Rates
2025
Eric O. Ansah | Jay R. Black | Ralf R. Haese
Copper is a critical metal required for green energy technologies such as wind turbines and solar cells. However, copper supply is limited by copper recovery from primary copper sulphides (e.g., chalcopyrite-CuFeS2) due to passivating reaction products. Therefore, this study examined surface &lsquo:passivation&rsquo: of primary copper sulphide minerals undergoing coupled dissolution with reprecipitation (CDR) reactions and the associated mineral surface changes in acidic and chloride-rich lixiviants (FeCl3-only, AlCl3-rich, NaCl-rich, and CaCl2-rich lixiviants). Acidic FeCl3-only, NaCl-rich, and CaCl2-rich lixiviants resulted in only bornite dissolution and the formation of a residual Cu-S phase and Fe-SO4 phase on the chalcopyrite surface. In contrast, leaching with the AlCl3-rich lixiviant resulted in both chalcopyrite and bornite dissolution with limited hydrolysis of Fe3+ to Fe-hydroxy sulphates and minimal Fe3+ flux inhibition to the copper sulphide minerals surface due to the ion exchange mechanism between Al3+ and Fe3+. Further, there was preferential formation of an Al-SO4 phase at consistently high Eh and acidity, thereby a high availability of Fe3+ in solution for enhanced copper dissolution from both bornite and chalcopyrite. These findings could serve as a reference for coupled dissolution with reprecipitation reactions during copper sulphide leaching, offering a pathway to more efficient and sustainable copper extraction from low-grade ores.
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