Thermal Decomposition of the Froth Flotation Mineral Sulfide Concentrates Under Argon Atmosphere in the Presence and Absence of Carbon

Thermal decomposition of the mineral sulfide concentrates derived from froth flotation was studied in the temperature range between 1073 K and 1473 K. The experiments were carried out by heating the mineral sulfide concentrates under inert (argon) atmosphere and, in the presence and absence of carbon. The thermal decomposition of the mineral sulfide concentrates were analyzed by plotting the weight loss of the sample against the reaction time which were obtained from the thermogravimeric analysis (TGA) and characterizing the reacted samples by X-ray diffraction (XRD) and microscopic techniques. The extent and rate of thermal decomposition of the samples were temperature dependent. The high sulfur minerals (CuFeS₂ and FeS₂) were decomposed to low sulfur and stable phases (Cu_1.1Fe_1.1S₂, Cu₅FeS₄, and FeS). However, the thermal decomposition of the mineral sulfides were complex because of liquid phase formation at high temperature such that the low sulfur phases appear to have precipitated from the liquid phase during cooling of the sample. Metallic copper was produced in the mineral concentrates containing hydrated and carbonated compounds. It was concluded that the formation of copper cannot occur in the absence of internal oxidation in the sample, when the mineral concentrates are heated under inert atmosphere. The phases were compared with the thermodynamic predictions.