Decomposition of enargite in nitrogen atmosphere

The thermal decomposition of enargite (Cu3AsS4) in nitrogen was investigate d by thermogravimetric analysis in the temperature range 575-700 degreesC, The decomposition proceeds in two consecutive stages through the formation of tenantite (Cu12As4S13) as an intermediate compound. The decomposition of enargite and the subsequent decomposition of tenantite follows first order kinetics. The activation energies were 125 and 236 kJ/mol for the first an d second stages, respectively. The final product of decomposition was a mix ture of chalcocite and non-stoichiometric sulfides (Cu1.8S,Cu1.96S).