The stoichiometry and kinetic of the hydrothermal reaction of enargite in copper sulphate solutions was investigated in the range 140–300 °C, and particle size under 15 and 50 microns.
The stoichiometric experiment was performed at 300°C, using one gram of sample (96% enargite, 4% tennantite) and 100 mL of copper sulphate solution (10 gpl) at 1.2 pH. Enargite reacted completely after 80 min. A solid product was obtained and characterized by XRD. The main product was chalcocite (M) and some traces of djurleite and chalcocite (Q). Tennantite did not react under this conditions.
The kinetic experiment were conducted at 140°C, 190°C, 250°C and 300°C. From fitted data and Arrhenius equation the calculated activation energy (Ea) was 51 kJ/mol.
According to the hydrothermal transformations studied, the reactivity of different phases found in the copper concentrates was bornite > chalcopyrite > covellite > sphalerite > pyrite > enargite > tennantite.