Yazar "Aydogan, S" seçeneğine göre listele

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    Critical solution surface tension for oil agglomeration
    (ELSEVIER SCIENCE BV, 2005) Ozkan, A; Aydogan, S; Yekeler, M
    This paper presents the effect of surface tension of solution used as medium for the oil agglomeration of minerals. Naturally occurring hydrophobic and hydrophilic minerals are used in this study. It was determined that the oil agglomeration recoveries of these minerals decreased with decreasing solution surface tension and the oil agglomeration process of the mineral did not occur below a particular value of solution surface tension. The solution surface tension value at which oil agglomeration does not take place was defined as 'the critical solution surface tension for oil agglomeration, gamma (c-a)'. These critical solution surface tension values obtained for those hydrophobic minerals were close to their critical surface tension of wetting (gamma(c)) values. On the other hand, the gamma(c-a) values obtained for the hydrophilic minerals treated with surfactants were slightly higher than their gamma(c) values. For a successful oil agglomeration of a mineral, the solution surface tension value must be higher than the critical surface tension of oil agglomeration (gamma(c-a)). (c) 2004 Elsevier B.V. All rights reserved.
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    Dissolution kinetics of malachite in ammonia/ammonium carbonate leaching
    (ELSEVIER SCIENCE BV, 2005) Bingol, D; Canbazoglu, M; Aydogan, S
    The leaching of oxide copper ore containing malachite, which is the unique copper mineral in the ore, by aqueous ammonia solution has been studied. The effect of leaching time, ammonium hydroxide, and ammonium carbonate concentration, pH, [NH3]/[NH4+] ratio, stirring speed, solid/liquid ratio, particle size, and temperature were investigated. The main important parameters in ammonia leaching of malachite ore are determined as leaching time, ammonia/ammonium concentration ratio, pH, solid/liquid ratio, leaching temperature, and particle size. Optimum leaching conditions from malachite ore by ammonia/ammonium carbonate solution are found as ammonia/ammonium carbonate concentrations: 5 M NH4OH+0.3 M (NH4)(2)CO3; solid/liquid ratio: 1:10 g/mL; leaching times: 120 min; stirring speed: 300 rpm; leaching temperature: 25 degreesC; particle size finer than 450 mum. More than 98% of copper was effectively recovered. During the leaching, copper dissolves as in the form of Cu(NH3)(4)(+2) Complex ion, whereas gangue minerals do not react with ammonia. It was determined that interface transfer and diffusion across the product layer control the leaching process. The activation energy for dissolution was found to be 15 kJ mol(-1). (C) 2004 Elsevier B.V. All rights reserved.
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    Dissolution kinetics of sphalerite in acidic ferric chloride leaching
    (ELSEVIER SCIENCE SA, 2005) Aydogan, S; Aras, A; Canbazoglu, M
    This paper presents a study for leaching kinetics of sphalerite concentrate in FeCl3-HCl solution. The shrinking core model was applied to the results of experiments investigating the effects of stirrer speed of 200-600 rpm, ferric ion concentration in range of 0-1 M, solid/liquid ratio in range of 1/100-1/5, leaching temperature range of 40-80 degrees C and particle size on zinc dissolution rate. The activation energy for the leaching process was found to be 45.30 kJ/mol and the Arrhenius constant was calculated to be 5.454 s(-1). The order of reaction for ferric ion concentration, solid/liquid ratio and particle size were also obtained. The rate of the reaction based on reaction-controlled process can be expressed as, [1 - (1 - alpha)(1/3)] = kappa(0)(Fe3+)(0.36)((rho S/L))(-0.33) r(0)(-0.97) exp((-45300/RT))t. The dissolution of sphalerite with acidic ferric chloride solution was found to be controlled by reaction-controlled process. (c) 2005 Elsevier B.V. All rights reserved.
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    Shear flocculation of celestite with anionic surfactants and effects of some inorganic dispersants
    (ELSEVIER SCIENCE BV, 2006) Ozkan, A; Ucbeyiay, H; Aydogan, S
    Shear flocculation characteristics of celestite (SrSO4) mineral have been investigated using sodium dodecyl sulfate (SDS) and Aero845 as anionic surfactants. The celestite suspension could be flocculated by SDS and Aero 845 in the broad pH range. However, these surfactants were slightly more effective on the celestite suspension at a pH of 7. The shear flocculation of celestite with SDS and Aero 845 increased rapidly with increasing surfactant concentration. However, it decreased at SDS concentrations higher than 45 mg/dm(3), and eventually stabilization of the suspension took place at concentration values above approximately 80 mg/dm3. From the experiments carried out to determine the effects of stirring speed and flocculation time on the shear flocculation of celestite suspension, it was found that a stirring speed of 500 rpm and a flocculation time of 3 min were required to achieve the maximum aggregation degree of celestite particles. The effects of sodium silicate, sodium phosphate and sodium polyphosphate used as inorganic dispersants on the shear flocculation of celestite were also studied. Sodium silicate strongly prevented the shear flocculation of celestite with SDS. However, the dispersive effect of sodium silicate was low in the presence of Aero 845. In the case of sodium polyphosphate, a dispersive effect on the celestite suspension was not observed for both surfactants. On the contrary, the shear flocculation power values increased slowly in the presence of sodium polyphosphate. In addition, the similar phenomenon also took place for sodium phosphate in the presence of SDS. (c) 2006 Elsevier B.V. All rights reserved.