Roasting of enargite (Cu3AsS4) in the temperature range of 648 K to 898 K (375 °C to 625 °C) in atmospheres containing variable amounts of oxygen has been studied by thermogravimetric methods. From the experimental results of weight loss/gain data and X-ray diffraction (XRD) analysis of partially reacted samples, the reaction mechanism of the enargite oxidation was determined, which occurred in three sequential stages: First stage: 4Cu3AsS4(s) + 13O2(g) = As4O 6(g) + 6Cu2S(s) + 10SO29g) Second stage: 6Cu2S(s) + 9O2(g) = 6Cu2O(s) + 6SO 2(g) Third stage: 6Cu2O(s) + 3O2(g) = 12CuO(s) The three reactions occurred sequentially, each with constant rate, and they were affected significantly by temperature and partial pressure of oxygen. The kinetics of the first stage were analyzed by using the model X = k1t. The first stage reaction was on the order of 0.9 with respect to oxygen partial pressure and the activation energy was 44 kJ/mol for the temperature range of 648 K to 898 K (375 °C to 625 °C).
|Number of pages||8|
|Journal||Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science|
|State||Published - Oct 2012|