Browsing by Author "Özbayoğlu, Gülhan"

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Citation - Scopus: 0
Commercial Coal Preparation Plants Capability for the Removal of Trace Elements
(Springer International Publishing, 2016) Özbayoğlu,G.; Energy Systems Engineering
Işiklar and Dereköy coal preparation plants clean lignite coals produced in Soma district. Run-ofmine coals contain trace elements and major elements that are associated with coal and inorganic matter. Trace elements are potentially harmful for human health and ecosystem. Physical coal cleaning is effective in reducing the concentration of many trace elements. In this study, the samples were collected from run-ofmine lignite (feed), coal preparation plant products, namely coarse (+18 mm) clean coal, fine (10-18mm, 0.5- 10mm) clean coals, middlings, coarse and fine refuses and slimes from the Dereköy and Işiklar plants systematically and chemical analyses of ash, trace and major elements were performed on each sample. Trace elements contents and distributions in each product were determined. During the cleaning of run-of-mine lignites in Işiklar and Dereköy coal preparation plants, 54.69% and 72.04% ash have been removed from the plants, respectively. Around 1/3 of Ga and Rb contents of Işiklar feed and more than 1/3 of Ga, Rb, Sr, contents of Dereköy feed could be removed by ash. Referring to major elements, rejection of 60% Ca and 53% Mg from Işiklar, and 69% Ca and around 80% Mg from Dereköy plants have been achieved. © Springer International Publishing Switzerland 2016.
Citation - WoS: 20
Citation - Scopus: 21
Comparison of Different Synthesis Methods To Produce Lithium Triborate and Their Effects on Its Thermoluminescent Property
(Springer, 2010) Depci, Tolga; Özbayoğlu, Gülhan; Ozbayoglu, Gulhan; Yilmaz, Aysen; Özbayoğlu, Gülhan; Energy Systems Engineering; Energy Systems Engineering
Lithium triborate (LiB3O5) was produced by different synthesis methods, which included high-temperature solid-state reaction, microwave-assisted high-temperature solid-state reaction, and precipitation-assisted high-temperature solid-state reaction. After the synthesis, metal oxides (CuO and Al2O3) were doped into LiB3O5 to enhance its thermoluminescent (TL) properties, and the TL intensities were compared with each other. The identification and characteristics of undoped and doped LiB3O5 were determined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) analyses, differential thermal analyses (DTA), scanning electron microscopy (SEM), and particle size analyzer. The glow curves were obtained by using a TL reader. The results showed that synthesis routes affected the physical and structural properties of lithium triborate, which have an important effect on its TL intensity.
Citation - Scopus: 2
Comparison of Gross Calorific Value Estimation of Turkish Coals Using Regression and Neural Networks Techniques
(2012) Ozbayoglu,A.M.; Ozbayoglu,M.E.; Ozbayoglu,G.; Energy Systems Engineering
Gross calorific value (GCV) of coals was estimated using artificial neural networks, linear and non-linear regression techniques. Proximate and ultimate analysis results were collected for 187 different coal samples. Different input data sets were compared, such as both proximate and ultimate analysis data, and only proximate analysis data and only ultimate analysis data. It was observed that the best results were obtained when both proximate analysis and ultimate analysis results were used for estimating the gross calorific value. When the performance of artificial neural networks and regression analysis techniques were compared, it was observed that both artificial neural networks and regression techniques were promisingly accurate in estimating gross calorific values. In general, most of the models estimated the gross calorific value within ±3% of the expected value.
Citation - WoS: 49
Citation - Scopus: 53
The Effect of Synthesis and Doping Procedures on Thermoluminescent Response of Lithium Tetraborate
(Elsevier Science Sa, 2011) Pekpak, E.; Yilmaz, A.; Ozbayoglu, G.; Energy Systems Engineering
Lithium tetraborate has been a scientific focus since 1960s by the courtesy of the thermoluminescence property it possesses. Moreover, it is utilized in surface acoustic wave apparatuses, in sensor sector and in laser technology owing to its non-linear optical characteristics. For the uses in thermoluminescence dosimetry lithium tetraborate is activated by addition of a variety of metals as dopants. This study includes the synthesis of lithium tetraborate by two methods (high temperature solid state synthesis and water/solution assisted synthesis), doping of activators into the matrix material synthesized and characterization of the products. Lithium tetraborate is readily commercially available in TL (Themoluminescence) dosimetry; hence, the main aim in this study was to specify the effect of synthesis and doping methods on the TL response. The heating temperature for the synthesis was 750 degrees C and the retention time as selected as 4 h for both methods. The synthesis stages were followed by doping step where the compounds of Cu, Ag and In in different proportions were doped in lithium tetraborate by solid state and solution assisted doping techniques. Characterization of the product was achieved by X-ray diffraction (XRD). Fourier transform Infra Red Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) techniques. All samples prepared displayed TL response and the best TL signal was obtained from the sample produced by solid state synthesis and doped by solution assisted method with 0.1% Cu and 0.004% Ag. (C) 2010 Elsevier B.V. All rights reserved.
Citation - Scopus: 0
Maghemite - a Source of Heavy Medium for Coal Washeries
(2010) Arol,A.; Ozbayoglu,G.; Anaç,S.; Bulut,M.; Energy Systems Engineering
Use of magnetite as heavy medium in coal preparation plants has been increasing steadily in recent years. It might be in short supply in some areas or excessively costly in certain times. In Turkey, the cost of heavy medium magnetite has almost tripled since 2003. As a result, alternative sources of heavy medium material have been evaluated. A maghemite ore from Elbistan-Kahramanmaras was found to be an interesting source. Tests showed that the maghemite ore can be enriched via magnetic separation at 1556 gauss to obtain a heavy medium material with 4.93 g/cm3 density and 97.22 per cent magnetic recovery. Further tests were conducted to determine the optimum fi eld strength for magnetic separation, friability and regeneration recovery.
Citation - WoS: 4
Citation - Scopus: 8
Partitioning of major and trace elements of a Turkish lignite with size and density
(oficyna Wydawnicza Politechniki Wroclawskiej, 2011) Ozbayoglu, Gulhan; Energy Systems Engineering; Energy Systems Engineering
This research was devoted to determine the concentration and distribution of major and trace elements in a Turkish lignite and to investigate the partitioning behaviour of them in various size and density fractions to estimate the possibility of removal of trace elements by conventional coal cleaning. Three size fractions which were used in industrial coal cleaning processes were chosen. Each size fraction was separated into various density fractions by float and sink tests, which were evaluated for major and trace elements. These tests showed that by applying the same size and density fractions of industrial coal cleaning processes, more than 70% of Mo, Nb, Nd, W, Hg and Zr could be removed, which were approximately equal to the result achieved for ash removal.
Citation - WoS: 5
Citation - Scopus: 7
Potential of Removing Trace Elements From a Turkish Lignite
(Taylor & Francis inc, 2010) Ozbayoglu, Gulhan; Energy Systems Engineering
Lignite is a significant source for producing electricity in Turkey. However, the hazardous trace elements content, namely, vanadium (V), chromium (Cr), copper (Cu), arsenic (As), thorium (Th), and uranium (U), are much higher than those observed around the world. In this article, the potential of removing the trace elements from the Lignite obtained from the Soma mine using the gravity separation principles is discussed. The float-sink studies conducted using heavy liquid of 1.3 and 1.9 specific gravities identified that removal of the trace elements from the Soma lignite ranged from 15% to 83%.
Citation - WoS: 6
Citation - Scopus: 0
Removal of Hazardous Air Pollutants Based on Commercial Coal Preparation Plant Data
(oficyna Wydawnicza Politechniki Wroclawskiej, 2013) Ozbayoglu,G.; Energy Systems Engineering
This paper investigates the concentration, distribution, and rejection of hazardous air pollutants, specifically identified by the US Clean Air Act Amendments of 1990, based on commercial coal preparation plant data obtained on-site. The samples were collected from the products of the different cleaning circuits of the operating plant. The concentrations of twelve potentially hazardous trace elements, including As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Se, Th and U in those samples were determined. Compared with the average concentration of the trace elements in Turkish coals, the run-of-mine coal fed to the existing plant appears to contain higher concentrations of Cd, Hg, Mn, Th and V. However, the concentrations of As, Cd, Cr, Mn, Se, Th, U and V of the run-of-mine coal are above the world averages. Cd, Cr, Hg, Mn, Pb and Th concentrations of run-of-mine coal were easily removed at commercial coal preparation plant refuse in the range of 51.8% to 77.4 %, while only a small reduction was achieved for U and V as they were concentrated in clean coals. The present study reveals that conventional coal preparation technologies could significantly reduce hazardous air pollutants concentrations in coal.
Citation - Scopus: 10
Removal of hazardous air pollutants based on commercial coal preparation plant data
(2013) Ozbayoglu,G.; Energy Systems Engineering
This paper investigates the concentration, distribution, and rejection of hazardous air pollutants, specifically identified by the US Clean Air Act Amendments of 1990, based on commercial coal preparation plant data obtained on-site. The samples were collected from the products of the different cleaning circuits of the operating plant. The concentrations of twelve potentially hazardous trace elements, including As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Se, Th and U in those samples were determined. Compared with the average concentration of the trace elements in Turkish coals, the run-of-mine coal fed to the existing plant appears to contain higher concentrations of Cd, Hg, Mn, Th and V. However, the concentrations of As, Cd, Cr, Mn, Se, Th, U and V of the run-of-mine coal are above the world averages. Cd, Cr, Hg, Mn, Pb and Th concentrations of run-of-mine coal were easily removed at commercial coal preparation plant refuse in the range of 51.8% to 77.4 %, while only a small reduction was achieved for U and V as they were concentrated in clean coals. The present study reveals that conventional coal preparation technologies could significantly reduce hazardous air pollutants concentrations in coal.
Citation - WoS: 21
Citation - Scopus: 19
Synthesis and Thermoluminescence Properties of Rare Earth Oxides (y, Ce-Lu) Doped Lithium Triborate
(Elsevier Science Bv, 2011) Depci, Tolga; Ozbayoglu, Gulhan; Yilmaz, Aysen; Energy Systems Engineering
Lithium triborate (LiB(3)O(5)) was synthesized by high temperature solid-state reaction method, and then rare earth oxides were doped into LiB(3)O(5) to enhance its thermoluminescent (TL) properties. The identification and characteristics of the obtained compounds were determined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) analyses, differential thermal analyses (DTA) and scanning electron microscopy (SEM). The glow curves were obtained using a thermoluminescent (TL) reader. The results revealed that all the rare earth oxides were not good activators for lithium triborate and the obtained compounds could not be used for dosimetric applications.
Citation - WoS: 6
Citation - Scopus: 6
Synthesis, Characterizations and Investigation of Thermoluminescence Properties of Strontium Pyrophosphate Doped With Metals
(Pergamon-elsevier Science Ltd, 2014) Ilkay, L. S.; Ozbayoglu, G.; Yilmaz, A.; Energy Systems Engineering
Strontium pyrophosphate, Sr2P2O7, was synthesized by solid-state synthesis method; the product was co-doped with copper-silver (Cu-Ag), copper-indium (Cu-In) and manganese-praseodymium (Mn-Pr) oxides (CuO, MnO, In2O3, Pr6O11 and AgNO3) by solid-state reaction method. The variation of dopant concentrations was investigated from 0.5 to 15% by weight. In addition to these processes, chemical characterizations of samples and the investigation of thermoluminescence (TLD) properties of strontium pyrophosphate with and without dopants were conducted. For the characterization; powder X-ray Diffraction (XRD) were implemented for phase purity of samples. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine whether the bond structures were affected from the doping or not. Thermoluminescence (TLD) analyses were conducted on strontium pyrophosphate doped with different amounts of dopants for the first time. Glow curves showed that intensities were affected by different amounts of dopants. It can be concluded from that strontium pyrophosphate doped with 7% MnO and 1% Pr6O11 had the most powerful peak intensity around 160 degrees C and dosimetric property for promising application. (C) 2014 Elsevier Ltd. All rights reserved.
Citation - WoS: 0
Use of Boric Acid as a Binder for Briquetting Some Boron Mine Wastes and Their Calcined Products
(Parlar Scientific Publications (p S P), 2010) Sener, Savas; Özbayoğlu, Gülhan; Ozbayoglu, Gulhan; Ozdemir, Zeynep; Özbayoğlu, Gülhan; Energy Systems Engineering; Energy Systems Engineering
In this study, boric acid as a binder for briquetting some boron mine wastes, such as colemanite and ulexite fines and calcined products, which do not meet the market specifications with respect to particle size, were investigated. Effects of water and binder contents, applied pressure, and curing and drying conditions on the briquette quality were evaluated in terms of mechanical strength, water-proofing characteristics and wearing resistance. The best briquettes were obtained at 62.4 MPa pressure (cured at ambient temperature for 24 h and dried at 105 C for 2 h). Only binder free briquettes of uncalcined ulexite gave satisfactory result. The briquette strength increased with an increase in the percentage of binder. The optimum binder content was found to be 5 % by weight for uncalcined ulexite and colemanite as well as calcined colemanite, but 10 To by weight for calcined ulexite. The water-proof briquettes of ulexite and calcined products of ulexite and colemanite fines could be produced. According to wearing resistance, ulexite and colemanite fines as well as calcined product of colemanite showed resistance to abrasion action during transportation and loading.