Yazar "Sis, Hikmet" seçeneğine göre listele
Listeleniyor 1 - 13 / 13
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Adsorption characteristics of ionic and nonionic surfactants on hydrophobic pigment in aqueous medium(Wiley-Blackwell, 2012) Sis, Hikmet; Birinci, MustafaThe current study is based on the investigation of the adsorption properties of ionic and nonionic surfactants on an organic hydrophobic pigment powder, namely, beta-copper phthalocyanine, in aqueous medium. The nonionic surfactants, selected systematically to represent varying degrees of ethoxylation, are nonylphenol ethoxylates, whereas the ionic surfactant is sodium oleate, a carboxylate-type anionic reagent. The adsorption of surfactants was assessed qualitatively by surface analysis of powders, before and after the adsorption of the surfactants. The experimental results were explained by the structural and other properties of the surfactants and the surface properties of the pigment. The specific adsorption of surfactants on pigments was verified by zeta potential measurements, as they altered the zeta potential values to a great extent. Nonionic surfactants decreased the absolute value of the zeta potential of the powder; whereas anionic surfactant sodium oleate shifted the zeta potential to more negative values. On the one hand, Fourier Transforminfrared and X-ray diffraction examinations of the pigments did not show any noticeable evidence for surfactant untreated or treated copper phthalocyanine. On the other hand, thermal analysis (both thermogravimetric and differential thermal analysis) showed clear evidence of the surfactants on both pigments, as substantial changes in thermogravimetric curves were assessed.Öğe An integrated process for rare earth elements recovery and silica production from Turkish bauxite-related ores(Taylor & Francis Ltd, 2026) Uysal, Turan; Erust, Ceren; Erdemoglu, Murat; Sis, HikmetThe evaluation of bauxite-associated shales as a secondary source of rare earth elements (REEs) is strategically important for securing a sustainable supply of critical raw materials used in advanced technologies. In this study, shale ore associated with bauxite, unsuitable for aluminium production due to its high silica content, was investigated as a potential resource for valuable REEs. The effect of thermal activation on REE recovery was examined, and the potential use of the leach residue as a silica source was assessed. Based on acid leaching results, the optimum calcination temperature was identified as 700 degrees C. Under these conditions, high REE recoveries were achieved: 92.9% La, 89.9% Ce, 89.0% Pr, 88.7% Nd, and 73.0% Sm. After leaching, the residue was enriched in alumina and silica. To improve silica purity and recover remaining REEs and Al, a second-stage leaching process was applied. This resulted in a byproduct containing 55% SiO2 with a specific surface area of 48 m2 g-1, indicating its potential as a silica source. The results demonstrate that bauxite-associated shale can be sustainably valorised through intensive milling, calcination, and acid leaching, enabling efficient REE recovery and the production of a silica-rich byproduct. L'& eacute;valuation de schistes associ & eacute;s & agrave; la bauxite comme source secondaire d'& eacute;l & eacute;ments de terres rares (ETR) est strat & eacute;giquement importante pour garantir un approvisionnement durable en mati & egrave;res premi & egrave;res critiques utilis & eacute;es dans les technologies avanc & eacute;es. Dans cette & eacute;tude, on a examin & eacute; le minerai de schiste associ & eacute; & agrave; la bauxite, inappropri & eacute; & agrave; la production d'aluminium en raison de sa teneur & eacute;lev & eacute;e en silice, comme ressource potentielle d'ETR pr & eacute;cieux. On a examin & eacute; l'influence de l'activation thermique sur la r & eacute;cup & eacute;ration des ETR et l'on a & eacute;valu & eacute; l'utilisation potentielle du r & eacute;sidu de lixiviation comme source de silice. D'apr & egrave;s les r & eacute;sultats de la lixiviation acide, on a identifi & eacute; la temp & eacute;rature optimale de calcination & agrave; 700 degrees C. Dans ces conditions, on a obtenu des r & eacute;cup & eacute;rations d'ETR & eacute;lev & eacute;es: 92.9% de La, 89.9% de Ce, 89.0% de Pr, 88.7% de Nd et 73.0% de Sm. Apr & egrave;s la lixiviation, le r & eacute;sidu & eacute;tait enrichi en alumine et en silice. Afin d'am & eacute;liorer la puret & eacute; de la silice et de r & eacute;cup & eacute;rer les ETR et l'Al restants, on a appliqu & eacute; une deuxi & egrave;me & eacute;tape de lixiviation. Cela a engendr & eacute; un sous-produit contenant 55% de SiO2 et pr & eacute;sentant une surface sp & eacute;cifique de 48 m2/g, indiquant son potentiel en tant que source de silice. Les r & eacute;sultats d & eacute;montrent que le schiste associ & eacute; & agrave; la bauxite peut & ecirc;tre valoris & eacute; de mani & egrave;re durable par broyage intensif, calcination et lixiviation acide, permettant une r & eacute;cup & eacute;ration efficace des ETR et la production d'un sous-produit riche en silice.Öğe Beneficiation of Complex Zinc-Lead Ores from Görgü (Malatya, Turkey) Region by Selective Flotation(Springer Heidelberg, 2024) Sis, Hikmet; Kiyak, Tufan; Erdemoglu, Murat; Demirkiran, Nizamettin; Aydogmus, RamazanThe growing demand for zinc and lead metals necessitated beneficiation of complex and oxidized zinc-lead ores, the ore types which are considered as difficult-to-float with conventional flotation. This study aimed to investigate flotation behavior of complex zinc-lead ores from G & ouml;rg & uuml; (Malatya) region that contains 2.92% Pb and 11.86% Zn. The characterization of flotation fractions by XRD, XRF, ICP, and elemental analysis provided valuable data for interpretation of the results. Studies revealed the effectiveness of various types and dosages of reagents in the flotation. It was found that high dosages of collector (e.g., 500 g/t KAX), sulfidizing agent (e.g., 5000 g/t Na2S.9H2O), and depressing/dispersing agents (e.g., 4000-5000 g/t Na2SiO3 and 2000-3000 g/t Na2CO3) was required to separate lead minerals effectively. In a single rougher flotation, a lead concentrate of 38.50% Pb grade could be obtained with 70.57% recovery. Nevertheless, zinc flotation results were not satisfactory as the zinc recovery and grade, respectively, could not exceed 17.70% and 17.01%.Öğe Dissolution kinetics of colemanite in HCl solutions by measuring particle size distributions(Taylor & Francis Inc, 2018) Sis, Hikmet; Bentli, Ismail; Demirkiran, Nizamettin; Ekmekyapar, AhmetDissolution kinetics of colemanite in hydrochloric acid solutions was investigated in this study. Particle size distribution data was, for the first time in the literature, utilized to investigate dissolution kinetics of colemanite. The size distribution of colemanite particles was measured in the reaction vessel during reaction, and the kinetic models were applied to particle size data. For comparison, the kinetic models were also fitted to the fractional conversion data, calculated from Ca concentration of the medium. Additionally, electrical conductivity and pH of the reaction medium were also recorded while measuring particle size distribution. Among the heterogeneous and pseudo-homogeneous models, Avrami model was found to be the best model to fit the particle size and fractional conversion data.Öğe Hidrofobik pigmentlerin reaktifler kullanılarak su içerisinde dağılma özelliklerinin arttırılması(2008) Sis, Hikmet; Seçkin, Turgay; Birinci, Mustafa; Kıvılcım, Nilüfer[Abstract Not Available]Öğe Influence of Marble Powder and Fly Ash on Rheological Properties and Strength of Cementitious Grouts(2021) Sis, Hikmet; Kıyak, Tufan; Fenerli, Cenk; Genç, MehmetThe usability of two environmentally important waste materials in cementitious fine grout production was investigated as partial replacement materials. The study is very important in reducing carbon footprint and cost in construction industry, and improving cement properties. The influence of replacement materials on flowability and strength was investigated by rheological and compressive strength tests. With marble powder replacement, a compressive strength of 26 MPa was achieved, which was fairly above the minimum compressive strength of 14 MPa. The flowability and strength of the mixes were heavily dependent on W/C ratio and affected by type and amount of replacement materials. Increasing W/C ratio and fly ash amount increased flowability, but inversely affected strength of the grouts. On the other hand, marble powder was found to increase the strength to a large extent, but decreased the flowability. The highest increase of 24 % and the lowest increase of 5.3 % on average were achieved with 10 % fly ash and 20 % marble powder replaced mixes, respectively. The rheology data, obtained in a wide shear stress-shear rate range, were found very useful in explaining flowability as well as setting behavior (rate) of grout mixes.Öğe Investigating dissolution of colemanite in sulfuric acid solutions by particle size measurements(Taylor & Francis Inc, 2019) Sis, Hikmet; Bentli, Ismail; Demirkiran, Nizamettin; Ekmekyapar, AhmetDissolution properties of colemanite and gypsum formation in sulfuric acid were investigated by measuring size distribution of particles in the reaction cell with time. After termination of the reaction, the remained material in the cell was analyzed to find out unreacted and reacted fractions. The results showed that the reaction of colemanite particles with sulfuric acid led to reduction in particle sizes and the degree of reduction depended on acids concentration and reaction time. The dissolution period and point of gypsum formation were clearly distinguished and marked on particle size plots.Öğe Optimization of rare earth elements recovery from Kızıldag (Karaman-Türkiye) shale ore using response surface methodology(Oficyna Wydawnicza Politechniki Wroclawskiej, 2025) Uysal, Turan; Unal, Ceren Erust; Akca, Muhammet Esat; Sis, Hikmet; Erdemoglu, MuratIn this study, the usability of bauxite-related shale ore, rich in Rare Earth Elements (REEs), to produce REEs, which have high added value and critical importance, was investigated. In this context, K & imath;z & imath;ldag (Karaman-T & uuml;rkiye) shale ore, was prepared for tests through size reduction and sampling processes. HCl leaching was performed at different acid concentrations, leaching times, leaching temperatures, and liquid/solid ratios to determine the optimum leaching conditions for the milled ore. The modeling and optimization parameters related to leaching recovery were investigated using the response surface method (RSM). The results were evaluated using analysis of variance, threedimensional graphs were drawn, and the accuracy of the models was discussed. Accordingly, optimum values were found, and the REE leaching recovery corresponding to these optimum values was 49.13%. It was concluded that the optimization results were compatible with the experimental results, and the average error rate (6.35%) was low.Öğe A Process Mineralogy Approach to the Flotation of Complex Lead-Zinc Ores from Gorgu (Malatya) Region(Springer Heidelberg, 2022) Altinisik, Ceylan Yarlugkal; Cebeci, Yakup; Sis, Hikmet; Kalender, LeylaComplex and non-sulfide lead-zinc ores are difficult to concentrate, but the growing demand for lead and zinc metals necessitated their beneficiation. Froth flotation is practically the most effective method in their beneficiation when optimum flotation conditions are attained. The aim of the current study is to use process mineralogy as a tool to understand the flotation behavior of these complex lead-zinc ores. The ore samples were characterized by element, XRD, MLA, thin section, and polished section mineralogical analysis, which clearly demonstrated oxidation and carbonation of the primary minerals. In the rougher flotation stage, a lead concentrate with 17.29% Pb and a zinc concentrate with 9.89% Zn could be obtained by 76.71% lead and 15.49% zinc recoveries from the ore samples containing 7.84% Zn and 4.54% Pb. The flotation results were delineated by process mineralogy data and poor results were explained in terms of (i) complex nature of the ore and similarity in the surfaces of different mineral particles, (ii) poly-metallic occurrence and spatial distribution of elements, (iii) poor liberation of particles, and (iv) lack of hydrophobicity on particle surfaces.Öğe Recovery of Zinc from Flotation Tailings of Lead-Zinc Ore Through a Hydrometallurgical Route(Springer, 2025) Sis, Hikmet; Kiyak, Tufan; Erdemoglu, Murat; Demirkiran, Nizamettin; Aydogmus, RamazanThis study focuses on recovering zinc from flotation tailings through a hydrometallurgical route, including sequential H2SO4 leaching, iron precipitation, and solvent extraction (SX) processes. The effect of leachate concentration, leaching temperature, and time on the zinc recovery was investigated at constant solid/liquid ratio and stirring rate. In order to remove impurities from the pregnant leach solution (PLS), dissolved iron was first precipitated with NaOH solution, and then the dissolved zinc ions were extracted selectively by D2EHPA. Finally, the zinc in the organic D2EHPA phase was stripped into an aqueous phase by utilizing H2SO4 solution to obtain a concentrated and purified zinc solution. It was seen that 93.50% of zinc in the tailings could be leached under optimum leaching conditions. In the SX process, the organic phases, prepared at organic/aqueous ratio (O/A) of 1/1 by volume, could extract 95.3% of the zinc in the pregnant leach solution within 10 min of extraction time. The stripping of 96.83% zinc into the aqueous phase was possible by using a 0.5-M H2SO4 solution, prepared at an O/A ratio of 1/1 by volume. Calculations showed that an 82.65% of cumulative zinc recovery could be achieved through the proposed leaching and SX route.Öğe Recycling process water in sulfide flotation, Part Effect of H2O2 and process water components on sphalerite flotation from complex sulfide(Soc Mining Metallurgy Exploration Inc, 2012) Ikumapayi, F.; Sis, Hikmet; Johansson, B.; Rao, K. HanumanthaHydrogen peroxide production was measured during the grinding of a complex sulfide ore, and its oxidizing effect on solid surfaces was investigated using Fourier transform infrared spectroscopy (FTIR) with diffuse reflectance attachment measurement. In turn, an attempt was made to correlate the formation of hydrogen peroxide, surface oxidation and sphalerite flotation. Additionally, in order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the effects of major components of calcium and sulfate species present in recycled process water and the effect of temperature on sphalerite flotation were investigated through bench-scale flotation tests using complex sulfide ores. The significance of process water species in flotation was studied using tap water, process water and simulated water containing calcium and sulfate ions. Formation of hydrogen peroxide was revealed during the grinding of the complex sulfide ore, and its formation was counteracted by diethylenetriamine (D ETA). The FTIR spectrum of the pulp solid fraction showed varying degrees of oxidized surface species; which are related to the concentration of H2O2 analyzed in pulp liquid. Bench-scale flotation using two different complex sulfide ores showed that sphalerite recovery is better in process water than in tap water. Flotation results also indicated a varied recovery of sphalerite at different temperatures in either tap water or process water.Öğe Removal of heavy metal ions from aqueous medium using Kuluncak (Malatya) vermiculites and effect of precipitation on removal(Elsevier, 2014) Sis, Hikmet; Uysal, TuranThe removal of heavy metal ions, Cr3+, Pb2+ and Zn2+, by vermiculite was studied by batch adsorption tests. Influence of experimental parameters (e.g., medium pH and initial ion concentration) on removal was examined separately. Metal hydroxide formation in the dispersions and their precipitation was also investigated to assess the effect of precipitation on ion removal. For this purpose, some removal tests were carried out in the absence of vermiculite at various pH and initial ion concentrations. Electrokinetic and other properties (e.g., specific surface area, thermal and chemical analysis) of vermiculite were determined to explain the experimental results and the interaction mechanisms between solid surface and the ions. Zeta potential data were found to be a very useful means to explain the interaction mechanism between the adsorbent and adsorbate. The affinity of vermiculite for ions changed in the order of Pb>Cr>Zn. At the lowest studied pH of 2.5, 15.81, 10.71 and 9.18 mg of Pb, Cr and Zn ions could be removed by 1 g of the adsorbent, respectively. (C) 2014 Elsevier B.V. All rights reserved.Öğe Wetting and rheological characteristics of hydrophobic organic pigments in water in the presence of non-ionic surfactants(Elsevier Science Bv, 2014) Sis, Hikmet; Birinci, MustafaWettability and rheological characteristics of highly hydrophobic organic pigments were determined in the absence and presence of surfactants. Two widely used pigments, carbon black (CB) and copper phthalocyanine blue (CuPc), were selected as model pigments. As wetting and dispersing agents, a range of non-ionic nonylphenol ethoxylated (NPE) surfactants with varying hydrophilic chain length was used in the tests. Wetting properties of the pigment powders were investigated by the contact angle measurements based on capillary rise method. Rheology experiments were carried out by a controlled shear stress rheometer. Rheological properties of pigment suspensions were determined by applying common rheologi cal models to shear stress (iota) versus shear rate (gamma) plots. The experimental results demonstrated that, highly ethoxylated surfactants were more efficient than less ethoxylated surfactants in reducing contact angle of pigment powders. Finally, it was inferred that CB and CuPc suspensions behaved virtually as Bingham plastic and shear thickening (dilatant) type suspensions, respectively. (C) 2014 Elsevier B.V. All rights reserved.
