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Öğe Dissolution kinetics of an oxidized copper ore in ammonium chloride solution(Croatian Soc Chemical Engineering Technology, 2003) Ekmekyapar, A; Oya, R; Künkül, AThe dissolution kinetics of malachite ore in ammonium chloride solutions has been investigated with respect to the effects of ammonium chloride concentration, particle size, solid/liquid ratio, stirring speed, and reaction temperature. It was determined that the dissolution rate increased with increasing ammonium chloride concentration, stirring speed, and reaction temperature. However, increasing particle diameter and solid to liquid ratio decreased the dissolution rate. Examination of data by heterogeneous model suggested that the dissolution rate is controlled by mixture kinetics. The following mathematical model was proposed to represent the reaction kinetics. 1 - 2(1 - x)(1/3) + (1 - x)(2/3) = 1 . 10(-5) (c)(2.10) . (d(p))(-1.96) . (rho(S/L))(-0.64) . (n)(1.78) . e((-8500/T) . t) The activation energy for the dissolution reaction was calculated as 71 kJ mol(-1). Where x is the reacted fraction of the solid, c is the ammonium chloride concentration, d(p) is the particle diameter, rho(S/L) is the solid to liquid ratio, n is the stirring speed, E is the activation energy, T is the reaction temperature and t is the reaction time.Öğe Dissolution kinetics of ulexite in ammonium sulfate solutions(Amer Chemical Soc, 2003) Künkül, A; Demirkiran, N; Baysar, AThe dissolution kinetics of ulexite in ammonium sulfate solutions was investigated. The effects of ammonium sulfate concentration, particle size, solid/liquid ratio, stirring speed, and reaction temperature on the dissolution rate have been evaluated. It was found that the dissolution rate increased with increasing ammonium sulfate concentration, stirring speed, and reaction temperature. However, increasing the particle size and solid/liquid ratio decreased the dissolution rate. Experimental data were examined by the heterogeneous and homogeneous models. The heterogeneous diffusion-controlled ash or product layer may describe the dissolution rate. The following mathematical model was used to represent the reaction kinetics: 1 - 3(1 - X)(2/3) + 2(1 - X) = 3.9 x 10(7) (CD-0.85)-D-0.64(S/L)(-1.06)omega(0.40)e(-10050/T)t, where X is the fractional conversion, C the ammonium sulfate concentration, D the particle size, S/L the solid-to-liquid ratio, omega the stirring speed, T the reaction temperature, and t the reaction time.Öğe Effect of operating parameters on magnetic filtration processes(Amer Chemical Soc, 2004) Künkül, A; Ekmekyapar, A; Akmil, C; Abbasov, TThe effect of operating parameters and the effect of the pH of the liquids to be cleaned on the magnetic filter performance in the filtration processes were investigated. The pH of aqueous suspensions containing ferromagnetic particulates was changed in the range of 3-10. The suspensions were prepared in our laboratory. The effect of the size of filter matrix elements (diameter of the ferromagnetic spheres) and filtration velocity on the filter performance was determined. The filter performance of the filter matrix composed of a mixture of different size spheres was also investigated. A magnetic filter performance above 60% was obtained with a filtration velocity of 0.07 m/s. It was observed that if the size of particles and the fraction of ferromagnetic particles in the suspension are varied in a short range, the effect of the initial concentration of corrosion products on the magnetic filter performance is negligible. The experimental results were compared with theoretical calculations and the data in the literature. Suggestions are given about choosing optimum values of the operating parameters for effective filtration of industrial fluids in magnetic filters.Öğe Removal of corrosion products from viscous aqueous suspensions by magnetic filtration(Elsevier Science Sa, 2004) Künkül, A; Abbasov, TThe removal of micron-sized corrosion products, which may occur during industrial processing by magnetic filtration, has been theoretically and experimentally investigated. The effect of alterations in theological properties of suspensions carrying particles on magnetic filter performance was determined. Magnetic filter dimensions were 0.03x0.04x0.09 in. The filter was filled with 6.35 X 10(-3) in diameter ferromagnetic spheres. Magnetic fields ranging from B=0 to B=1.4 T perpendicular to the flow direction were applied. The suspension flow rate through the magnetic filter was 0.4 m/s. It was determined that 85% of corrosion products show magnetic properties. The magnetic filtration of suspensions composed of water, corrosion products and glycerine at different concentrations was studied. The effects of initial concentration of corrosion products, viscosity of aqueous suspension, magnetic field intensity and the number of filtration cycles on magnetic filter performance were determined. Theoretical and experimental results were in good agreement. (C) 2004 Elsevier B.V. All rights reserved.
