Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026Scopus SJRQ1/r/bayburt/11421
  Multi-parameter hydrodynamic analysis of pulsation frequency and waveform effects in a conical spouted bed: A CFD study

  Çutay, Arif; Tozlu, Alperen; Kütük, Begüm; Özahi, Emrah

  The hydrodynamic behavior of spouted beds is strongly influenced by inlet flow conditions, particularly under pulsating operation. In this study, a three-dimensional Eulerian–Eulerian two-fluid model coupled with the kinetic theory of granular flow was used to investigate the effects of pulsation frequency and waveform on the hydrodynamics of a conical spouted bed. Steady, sinusoidal, pulsatile, and square-wave inlet conditions were analyzed at 1, 3, 5, and 10 Hz. A multi-parameter evaluation framework was applied by combining spout height, temporal stability, axial gas and particle velocity distributions, and mixing characteristics. Spout height was determined using the connected αs=0.05 iso-contour, while temporal behavior was quantified through the mean spout height, standard deviation, coefficient of fluctuation, and fluctuation range. The results show that spout performance depends not only on instantaneous inlet velocity but also on the persistence of axial momentum transfer. Although the steady condition and some high-penetration pulsating cases produced relatively large instantaneous spout heights, they did not necessarily provide the most favorable hydrodynamic behavior because of rapid velocity decay, stronger fluctuations, or reduced structural coherence. Pulsation at 3 Hz provided the best overall balance by sustaining particle transport and improving temporal stability. The 5 Hz cases enhanced mixing but exhibited larger fluctuations, whereas the 10 Hz cases produced weaker and less coherent spout structures because of rapid attenuation of the imposed oscillations. Overall, the proposed framework demonstrates that spouting performance should be evaluated through the combined effects of penetration, stability, momentum persistence, and mixing.

  AtıfOpenAlex1

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• MakaleYalnız künye2025Scopus SJRQ1/r/bayburt/11030
  Optimization of surface modification parameters of fly ash with high calcium oxide (CaO) content to use as a filling material

  Uçurum, Metin; Özdemir, Akın; Teke, Çağatay

  Fly ash (FA) is the fine-grained waste product obtained by burning coal after being ground to specific sizes in thermal power plants, carried with flue gases, and kept in cyclones or electro-filters. Like every industrial waste, the possibilities of utilizing FA have been investigated, and it can be utilized as an additive in cement and concrete. Despite this, industrial waste, which increases daily in the world, brings many problems, especially environmental problems. For this reason, alternative usage areas of the waste in question are constantly being investigated. In this paper, FA containing approximately 50 % CaO from Afşin-Elbistan, Turkiye was processed with stearic acid in a planetary mill to be used as a filling material in industrial products, and it has a grain size of 68.10 μm on a d50 basis, a specific surface area (SSA) of 176.40 m2/g and a contact angle of 13.89. An optimization and characterization study was conducted to make the hydrophilic surface structure hydrophobic by mechanochemical surface modification. Also, surface modification parameters, such as operational speed (rpm), ball filling ratio (%), FA filling ratio (%), pulp density, stearic acid dosage (% of FA), and modification time (min.) were optimized with the D-optimal experimental design. Based on the optimum surface modification parameters, a coated fly ash (CFA) product was obtained with an active ratio of 99.70 %, a contact angle of 95.06o, a medium size (d50) size of 10.60 μm, and an SSA of 926.90 m2/g.

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  AtıfScopus8·WoS8·OpenAlex9

  İncele
• MakaleYayıncıda açık erişim2024Scopus SJRQ1/r/bayburt/13085
  Wet mechanochemical surface modification of calcite employing an integration of conventional design and analytical hierarchy process

  Uçurum, Metin; Özdemir, Akın

  The demand for ultra-fine mineral powders from various industries requires the applications of wet grinding and surface modification. In this study, wet mechanochemical surface modification of micronized calcite (d50 = 4.92 μm) with stearic acid [CH3(CH2)16COOH] was carried out in a planetary ball mill. The seven parameters were specified: ball filling ratio (%), ball size distribution ratio (10 and 15 mm, %), micronized calcite filling ratio (%), pulp solid ratio (wt%), mill speed (rpm), stearic acid dosage (% of micronized calcite) and modification time (min). Then, these parameters were optimized using a conventional experimental design when maximizing the active ratio (%) as a significant value for coated calcite. Besides, the analytical hierarchy process was applied to observe the importance of each parameter. Stearic acid dosage, mill speed, and micronized calcite filling ratio are the top three parameters affecting the active ratio. Next, size distribution, XRF, XRD, SEM, FTIR, TGA-DTA, contact angle, and whiteness measurements were performed on the micronized calcite (MC) and coated micronized calcite (CMC) samples. The final CMC product had a 99.90% active ratio, 2.49 μm mean (d50) particle size, and 101.66o contact angle. Finally, CMC obtained by the surface modification can be used as a filler mineral.

  AtıfScopus6·WoS4·OpenAlex7

  İncele
• MakaleAçık Erişim2024Scopus SJRQ1/r/bayburt/12821
  Optimization of mechanochemical surface modification parameters on planetary mill using an I-optimal experimental design

  Özdemir, Akın; Uçurum, Metin

  Several micro-particle-size additives and filler minerals are added to many industrial products, especially plastic, in order to reduce cost and improve mechanical properties and appearance. Also, grinding and surface modification are two fundamental properties of the filler minerals used in plastic products. Notably, Bayburt stone (BS) used as a natural raw material from Bayburt, Türkiye contains 76% SiO2 and 15% Al2O3. In this paper, the hydrophilic surface structure of micronized Bayburt stone (MBS) was made hydrophobe by mechanochemical surface modification using calcium stearate [Ca(C17H35COO)2] in a laboratory-type planetary mill. Next, the optimum conditions of the surface modification design factors, which are (1) ball filling ratio = 30.53%, (2) powder filling ratio = 10.43%, (3) mill speed = 475.91 rpm, (4) chemical dosage = 1.99% of powder, and (5) modification time = 4.83 min., were obtained using the proposed I-optimal design-focused optimization model when predicting the model parameters. In addition, a coated micronized Bayburt stone (CMBS) product with an active ratio (AR) of 99.90% and d10, d50, and d90 values of 1.32 μm, 3.48 μm and 9.55 μm were achieved. Finally, particle size distribution (PSD), thermo-gravimetric and differential thermal analyzer (TG-DTA), Fourier transform infrared (FTIR), scanning electron microscope (SEM), electron dispersive spectrum (EDS), and contact angle analyses were performed on the CMBS product.

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  AtıfScopus5·WoS6·OpenAlex6

  İncele
• MakaleAçık Erişim2023Scopus SJRQ1/r/bayburt/11914
  A new approach for high-quality production of UHMWPE by applying powder vibration densification before sintering

  Yilmaz, Galip; Uslu, Emin

  Due to its extreme viscosity, UHMWPE powder requires elevated pressure and temperature settings to ensure a fully solid structure. But a gentle process is vital for reliability in certain applications, such as prosthetic liners. A unique type of large gap, not mentioned in the literature, has been observed to resist closing more than regular gaps due to the number of particles forming a shield against pressure. As a solution, a mechanical vibration treatment of the particles before heating was used to eliminate these particular large gaps. Optimum vibration parameters were found, and the samples' final solid density and mechanical properties increased. The particles' dimensions and coefficient of friction were measured, and their vibration-dependent characteristics were discussed. A custom-made microscope apparatus was used to observe the vibration-induced densification of the particles and the gaps resisting closing.

  AtıfScopus14·WoS14

  İncele
• MakaleAçık Erişim2016Scopus SJRQ1/r/bayburt/13789
  An experimental study on the ultra-fine grinding of gypsum ore in a dry ball mill

  Öksüzoğlu, Bilge; Uçurum, Metin

  Gypsum is a crystalline form of hydrated calcium sulfate (CaSO4·2H20) generally used in cements and plasters in the construction industry, though also in paints, fertilizers, medicines, papers, and textiles. For use in these materials, gypsum must be ground finely (<100 μm), if not ultra-finely (<10 μm), for which ball mills are most effective. Despite gypsum's widespread use and the regular need to grind it, studies concerning the grinding of gypsum ore remain scarce. In response, in this study, we have systematically investigated how certain grinding parameters (i.e., mill speed, ball filling ratio, ball size distribution, powder filling ratio, grinding aid ratio, and grinding time) of conventional dry ball mills affect the grindability of gypsum ore. We determined the properties of the micronized gypsum products obtained in optimal grinding conditions, and the results showed that the dry ball mill grinding process can effectively produce ultra-fine gypsum products.

  AtıfScopus38·WoS32·OpenAlex42

  İncele
• MakaleAçık Erişim2015Scopus SJRQ1/r/bayburt/12565
  Numerical modeling of cold powder compaction using multi particle and continuum media approaches

  Güner, Faruk; Cora, Ömer Necati; Sofuoğlu, Hasan

  Numerical analysis of powder compaction process requires multi-particle modeling approach as continuum models fail to simulate the nature of process (e.g. interparticle, and particle-die interactions), accurately. This study aimed for analyzing powder compaction process utilizing 3-D finite element modeling approach along with different material models including modified Cam-Clay, Mohr-Coulomb, Shima-Oyane and von-Mises. The finite element analyses were carried out by implementing multi-particle finite element method. Moreover, continuum modeling was also performed for comparison purposes. In both cases, the compaction of spherical copper particles was analyzed at room temperature conditions. The obtained FEA results were compared in terms of equivalent stress and strain, and deformed shape. Results showed that the FE models in which von-Mises and modified Cam-clay material models were used yielded results of similar magnitude while those of Shima-Oyane and Mohr-Coulomb material models resulted in equivalent stress and strain values are in close proximity. Effect of coefficient of friction on the results was also investigated by implementing three distinct coefficients of friction ( μ= 0.1, 0.25, 0.4). It was noted that increasing friction resulted in elevated level of deformation for the particles and harsher particle-particle, and particle-die contact interactions.

  AtıfScopus72·WoS67·OpenAlex76

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