Influence of tartrate on leaching interface of low-grade polymetallic complex chalcopyrite ore

The leaching of Cu from low-grade polymetallic complex chalcopyrite ore (LPCCO) in acidic ferric electrolyte was increased by adding tartrate. To explain the reason resulting in this phenomenon, a systematical study about the effects of tartrate on the interfaces where reactions occurred was conducted by using electrochemical methods. The Mott−Schottky experiment results showed that whether tartrate was added or not, the initial n-type LPCCO surface transformed to the surface with a p−n junction that seriously hindered charge transfer. After adding tartrate, a shorter Debye length and higher charge carrier density were obtained, which were related to the decrease in intergranular energy barrier height by tartrate's bridging semiconductor particles. Additionally, EIS results combined with Tafel and LSV analysis revealed thin passive film and double-layer, large diffusion coefficient, and low apparent activation energy. These favorable changes in interface properties facilitated the LPCCO dissolution.