Leaching and kinetic modeling of calcareous bornite in ammonia ammonium sulfate solution with sodium persulfate

• The bornite was leached out by ammoniacal solution with sodium persulfate.
• The dissolution rate of calcareous bornite was described by the unreacted-core model.
• The model was affected by the interface transfer and diffusion through a layer.
• The layer was composed of S and Fe2O3.
• The oxidation mechanism of bornite was illuminated clearly.

The leaching process of copper from calcareous bornite using sodium persulfate as an oxidant in ammoniacal solution was investigated. The effects of agitation speed, leaching temperature, concentration of ammonia and ammonium sulfate, and dosage of sodium persulfate on the leaching rate of copper from bornite ore were determined. The results indicate that the leaching rate is nearly independent of agitation above 400 rpm and increases with increasing temperature, concentration of ammonia and ammonium sulfate and dosage of sodium persulfate. The leaching kinetics was analyzed by a new variant of the shrinking core model (SCM) in which both the interfacial transfer and the diffusion across the product layer affect the leaching rate, and its apparent activation energy was found to be 15.6 kJ/mol.