Investigation of the Thermal Decomposition Kinetics of Chalcopyrite Ore Concentrate usng Thermogravimetric Data
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The kinetics of the thermal decomposition of chalcopyrite concentrate was investigated by means of thermal analysis techniques, Thermogravimetry/Derivative thermogravimetry (TG/DTG) under ambient air conditions in the temperature range of 0-900 degrees C with heating rates of 2, 5, 10, 15, and 20 degrees C min(-1). TG and DTG measurements showed that the thermal behavior of chalcopyrite concentrate shows a two-step decomposition. The decomposition mechanism was confirmed using X-ray diffraction (XRD), Scanning Electron Microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) analyses. Kinetic parameters were determined from the TG and DTG curves for steps I and II by using two model-free (isoconversional) methodsFlyn-Wall-Ozowa (FWO) and Kissinger-Akahira-Sunose (KAS). The kinetic parameters consisting of E-a, A, and g() models of the materials were determined. The average activation energies (E-a) obtained from both models for the decomposition of chalcopyrite concentrate were 72.55 and 300.77kJmol(-1) and the pre-exponential factors (A) were 15.07 and 29.39 for steps I and II, respectively. The most probable kinetic model for the decomposition of chalcopyrite concentrate is an first-order mechanism, i.e., chemical reaction [g()=(-ln(1-))], and an Avrami-Eroeyev equation mechanism, i.e., nucleation and growth for n=2 [g()=(-ln(1-)(1/2))], for steps I and II, respectively.