Pyrite as a sulfidation agent in chrysocolla sulfidation roasting for copper recovery: Thermodynamics, phase transformation, and sulfur migration

Chrysocolla is an important refractory copper oxide ore. The sulfidation roasting using pyrite as a sulfidation agent was conducted on the chrysocolla. A copper recovery of 87.31 % was obtained with butyl xanthate. Thermodynamic analysis indicated that the predominant equilibrium product was Cu 2 S. Excessive pyrite dosage resulted in an overproduction of by-products, and a satisfactory equilibrium composition can be obtained at a roasting temperature above 500 °C. The main gas product was SO 2 , with no H 2 S generated. The roasting process involved the dehydration of chrysocolla, forming copper oxides that reacted with S released from pyrite pyrolysis. The sulfidation reaction gradually proceeded from the particle surfaces to the interiors with the gradual S diffusion. Even with satisfactory copper recovery, a significant amount of copper oxides remained within the particles. This was because xanthate primarily adsorbed onto the particle surface, implying that complete copper mineral phase reconstruction may be unnecessary for efficient flotation.