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Öğe Comparison of stages in oil agglomeration process of quartz with sodium oleate in the presence of Ca(II) and Mg(II) ions(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2009) Ozkan, Alper; Ucbeyiay, Hawanur; Duzyol, SelmaThe oil agglomeration of quartz with sodium oleate in the presence of calcium and magnesium ions comprises three consecutive stages: adsorption of cations onto quartz surfaces, which leads to coagulation of the Suspension, shear flocculation with sodium oleate and finally, agglomeration of flocs by kerosene. The effects of pH and cation concentration on these stages were investigated and the results were presented comparatively. It was found that all the stages of oil agglomeration of quartz exhibited sharp dependences on pH and cation concentration. That is, these stages generally took place in the pH and concentration ranges in which hydroxy complexes of the cations existed in the Suspension. In the case of magnesium ion, the coagulation, shear flocculation and especially oil agglomeration of quartz improved after precipitation of hydroxide. These species of calcium and magnesium ions formed at high pH were adsorbed oil the negatively charged Surface of quartz, as a result Of which the adsorption of sodium oleate became possible and thus the shear floccuation of the particles was achieved. Thereafter, the hydrophobic quartz flocs could be agglomerated by kerosene as bridging liquid. The increase in the shear flocculation efficiency depending oil the increase of surface hydrophobicity enhanced the oil agglomeration of quartz with kerosene. The maximum recoveries for all the stages of the quartz were obtained in the presence of 10(-3) M magnesium and 5 x 10(-3) M calcium ions at pH 11. However, some differences in file behavior of shear flocculation and oil agglomeration of quartz suspension were observed above 10(-3) M concentration of magnesium ion. (C) 2008 Elsevier Inc. All rights reserved.Öğe EVALUATION OF FLOCCULATION BEHAVIOR OF MARBLE POWDER SUSPENSIONS(OFICYNA WYDAWNICZA POLITECHNIKI WROCLAWSKIEJ, 2015) Duzyol, SelmaIn this study, flocculation of marble powder suspensions was investigated depending on a polymer type and dosage. Polyacrylamide was used as a synthetic polymer, while starch was used as a natural polymer. The effect of polyacrylamide type was also examined using anionic, cationic and nonionic polyacrylamides. Flocculation of suspensions was ascertained by turbidity measurements. It was found that anionic and especially non-ionic polymers flocculated the marble powder suspension more strongly than starch and cationic polymer. On the other hand, it was observed that the sequential addition of starch and polymer did not improve flocculation of suspension. On contrary, sequential addition of flocculants caused re-dispersion of the flocculated suspension. When a non-ionic polymer was used as the flocculant, the reached minimum turbidity of suspension was measured to be 38 NTU (nephelometric turbidity unit).Öğe Investigation of oil agglomeration behaviour of Tuncbilek clean coal and separation of artificial mixture of coal-clay by oil agglomeration(ELSEVIER, 2015) Duzyol, SelmaOil agglomeration technique is one of the several major physicochemical separation processes in fine particle processing. In this study, the oil agglomeration behaviour of Tuncbilek clean coal was investigated and studied to find operating parameters that would decrease the ash content of the clean coal. The optimum conditions for agglomeration time, kerosene concentration and stirring speed were determined to be 20 min, 31.6 wt.%, and 1500 rpm, respectively. Also, the ash content of the coal could be decreased by the addition of methanol. The separation of various artificial mixtures of coal-clay samples was also investigated under the determined optimum conditions. The coal could be agglomerated with above 80% of combustible recovery. The ash content was nearly the same for all conditions and determined to be approximately 6%. The coal was separated from clay minerals with high combustible recovery and low ash content using selective oil agglomeration technique. (C) 2015 Elsevier B.V. All rights reserved.Öğe INVESTIGATION OF THE OIL AGGLOMERATION OF ESKICELTEK LIGNITES IN TURKEY(STEF92 TECHNOLOGY LTD, 2014) Duzyol, Selma; Sensogut, CemOil agglomeration is one of the effective separation techniques that can be performed for the beneficiation of the fine particles in mineral processing. The oil agglomeration behavior of Eskiceltek, Amasya lignites was investigated in the present work. Raw lignite sample having an upper calorific value of 3046.8 kcal/kg has 51.03% of ash content. The experimental conditions were conducted as taking kerosene concentration, pH and agglomeration time into consideration. After realizing the oil agglomeration experiments, lignite sample was enriched with the ash content of 29.4% and 78% of combustible recovery.Öğe Investigation of the Thermal Improvement and the Kinetic Analysis of the Enriched Coal(HINDAWI LTD, 2018) Duzyol, Selma; Sensogut, CemThe present research work is comprised of three main parts. The first part is about the enrichment of lignite coal by the utilization of dense medium separation called float and sink method. The second part deals with the investigation of the thermal behaviour for the coals enriched while the last part is concerned with the kinetic analysis of the coal combustion. The float and sink method is the mostly used technique for low-rank coal beneficiation in coal preparation plants of Turkey. In order to realize this process, the coal samples were, at first, fractioned to five different sizes which were -32+ 25 mm, -25+ 16 mm, -16+ 8 mm, -8+ 4.75 mm, and -4.75+ 2 mm. Each fraction was, then, processed in the dense mediums with the specific gravities of 1.20, 1.30, 1.40, 1.50, and 1.60 g/cm(3), respectively. The thermal behaviour of the floated materials from the float and sink process was investigated in detail with the thermogravimetric analysis (TG) and the differential thermogravimetric analysis (DTG). The ignition and peak temperatures for the samples were also ascertained and correlated with the float and sink test results. In the final part of the study, the kinetic analysis of the coal samples was carried out by the Coats-Redfern method and the activation energies of the enriched coals were determined. The activation energies of the raw and the enriched coals were assessed and compared. The calculated activation energy values for the combustion reactions of the coal samples ranged were found to be between 15.17 kJ/mol and 97.45 kJ/mol. The strong correlation was obtained between the float and sink test results especially with the ash content of the coal samples and the combustible characteristic of the floated materials such as ignition temperatures, peak temperatures, and activation energies. The combustion characteristics of the coal samples were resultantly ascertained to be very dependent on the coal structure.Öğe A STUDY ON SHEAR FLOCCULATION OF MAGNESITE SUSPENSIONS(INT SCIENTIFIC CONFERENCE SGEM, 2008) Duzyol, Selma; Ozkan, AlperShear flocculation characteristics of magnesite with sodium oleate as anionic surfactant have been investigated in this study. The effects of various parameters such as pH, stirring speed and concentration of sodium oleate on the shear flocculation of magnesite were determined. It was found that the shear flocculation of magnesite was not affected much by the pH changes of the suspension. However, the flocculation of magnesite showed strong dependences on stirring speed and surfactant concentration. By evaluation of the experimental results, optimum conditions for shear flocculation of magnesite were determined as: pH, alkaline levels; sodium oleate concentration, 20 mg/dm(3) and stirring speed, 500 rpm. Under these optimum conditions, magnesite fines in the suspension could be flocculated with a recovery of 84%.
