Investigation of the Thermal Decomposition Kinetics of Chalcopyrite Ore Concentrate usng Thermogravimetric Data

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.