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    Determination of the Optimum Conditions for Copper Leaching from Chalcopyrite Concentrate Ore Using Taguchi Method
    (Taylor & Francis Inc, 2015) Çopur, Mehmet; Kizilca, Meltem; Kocakerim, M. Muhtar
    The optimum conditions for the extraction of copper from chalcopyrite concentrate into SO2-saturated water were evaluated using the Taguchi optimization method. High level copper recovery was obtained in an environmentally friendly process that avoids sulfur dioxide emission into the atmosphere because SO2 forming in the roasting is used in the dissolution. Experimental parameters and their ranges were chosen as follows: reaction temperature, 293-333 K; solid-to-liquid ratio, 0.025-0.15 g/mL; roasting time, 30-90 min; roasting temperature, 773-973 K; stirring speed, 400-800 rpm; and reaction time, 10-60 min. The particle size and gas flow rate were 63 mm and 10 cm(3)/min, respectively. The optimum conditions of the dissolution process were determined to be reaction temperature of 318 K, a solid-to-liquid ratio of 0.025 gmL(-1), a roasting time of 75 min, a roasting temperature of 773 K, a stirring speed of 400 rpm, and a reaction time of 30 min. Under optimum conditions, dissolution yield of copper was 91%.
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    Investigation of the Thermal Decomposition Kinetics of Chalcopyrite Ore Concentrate usng Thermogravimetric Data
    (Taylor & Francis Inc, 2016) Kizilca, Meltem; Çopur, Mehmet
    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.
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    Kinetic Investigation of Reaction Between Colemanite Ore and Methanol
    (Taylor & Francis Inc, 2015) Kizilca, Meltem; Çopur, Mehmet
    In the field of industry, it is very important that boron compounds are produced from boron ores. The aim of this study was to investigate the dissolution kinetics with carbon dioxide of colemanite in methanol medium in a pressure reactor and to derive an alternative process for producing boron compounds. Reaction temperature, stirring speed, solid/liquid ratio, pressure, and particle size were selected as parameters for the dissolution rate of colemanite. It was found that the dissolution rate increased with increase in pressure and reaction temperature, and with decrease in particle size and solid/liquid ratio. No effect of stirring speed was observed on conversion. The dissolution kinetics of colemanite were examined using both heterogeneous and homogeneous reaction models, and it was determined that the reaction rate can be described by a second-order pseudo-homogeneous reaction model. The activation energy was found to be 51.4 kJ/mol.
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    Thermal dehydration of colemanite: kinetics and mechanism determined using the master plots method
    (Taylor & Francis Ltd, 2017) Kizilca, Meltem; Çopur, Mehmet
    Dehydration kinetics of colemanite ore were explored using thermogravimetric analysis techniques (thermogravimetry (TG)/derivative thermogravimetry (DTG)) in the range of 0-1000 degrees C at heating rates of 2, 5, 10 and 20 degrees C min(-1) in an inert (N-2) atmosphere. Kinetic triplets which were activation energy, pre-exponential factor and reaction mechanism were obtained from the TG and DTG applying six model-free (isoconversional) methods, i.e. Kissinger-Akahira-Sunose (KAS); Flyn-Wall-Ozawa (FWO); Tang, Starink and iterative KAS and iterative FWO. The researcher tested the reliability of the study method in identifying the kinetic mechanism by comparing experimental master plots to theoretical master plots. Structural and morphological properties were carried out using X-ray diffraction, Fourier transform infrared and scanning electron microscopy-energy disperse spectroscopy methodologies.