Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026/r/gumushane/12230
  Hydrometallurgical Extraction of Aluminum and Rare-Earth Elements (REEs) from REE-Bearing Bauxite Ores: Recent Advances

  Uysal, Turan; Supriyatna, Yayat Iman

  Rare-earth elements (REEs) are geologically widespread, but their mining and especially processing are concentrated in a small number of countries; as demand grows, some specific REEs may face supply shortages in the near future. Consequently, owing to their economic potential even at low concentrations, ability to provide alternative supply opportunities, and process development potential, various countries are conducting studies on REE production from secondary geological sources such as high-silica bauxite ore. This study provides a detailed examination of aluminum (Al) and REE recovery from bauxite ore, emphasizing sustainable utilization of these resources. In this context, the study presents the technological evaluation potential of these deposits in the context of modern demands, the acquisition process, and an analysis of the main technical difficulties in this process. Furthermore, the application of both mechanical and thermal activation methods in conjunction may prove more economically viable and environmentally sustainable by reducing the temperature requirements of fossil fuel-consuming heat treatment. The development of sustainable Al and REE recovery technology from bauxite ore is of significant importance, not only in terms of mitigating supply risk but also as an alternative source for REE production.

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• MakaleYalnız künye2023/r/gumushane/12827
  Effect of Plastic Deformation on the Mechanical Properties of Dual-Phase Steels Using Nanoindentation

  Ekmekci, Dursun; Uşun, Altuğ; Cora, Ömer Necati

  The mechanical properties of two advanced high-strength steels (AHSS), DP 1000 and DP 1200 dual-phase (DP) grades, under deformed and undeformed conditions, were investigated using nanoindentation, and the results were compared with those obtained from the conventional methods. To this goal, 3-point bending tests were applied to induce deformation in the samples. Before and after these tests, nanoindentations were performed at different forces and indentation depths. In addition to the hardness and modulus of elasticity values of the steels, the residual stresses on the samples after deformation were obtained by using the equations suggested in the literature, also with x-ray diffraction (XRD). Finite element (FE) modeling of 3-point bending and nanoindentation were performed to obtain stress–strain curves of the materials numerically. The stress–strain curves obtained by numerical analysis agree well with those reported in the literature. The variations of the hardness and modulus of elasticity values are narrower for deeper indentation (50 nm versus 200 nm), and the effect of deformation is more pronounced on the modulus of elasticity values (10–30% increase with the deformation) while hardness values increased with the effect of deformation, 10% at most.

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• MakaleYalnız künye2021/r/gumushane/14629
  Extraction of Metals from Scrap Marble Cutting Segments in Nitric Acid Solutions

  Celep, Oktay; Orak, Mürsel; Yazici, Ersin Y.; Deveci, Hacı

  Extraction of cobalt, copper, and silver from scrap saw-blade segments using nitric acid solutions (0.1–0.4 M, 20–60°C) were investigated using response surface methodology. Extraction of cobalt and iron was more extensive than copper and silver, i.e., 35.7–96.2% Co and 72.6–100% Fe versus 8.50–35.4% Cu and 8.11–22.5% Ag. Statistical analysis of the experimental data has shown that increasing the acid concentration or temperature enhances the rate and extent of leaching of metals. Under suitable conditions, almost complete leaching of cobalt (99.9%), as well as high extractions of copper (95.9%) and silver (94.9%), were achieved. The activation energy, calculated to be 40.3 kJ/mol, indicates that nitric acid leaching of these metals occurs as a chemically controlled reaction. These findings have demonstrated that nitric acid as an effective oxidant/leaching agent could be suitably used for the extraction of cobalt, copper, and silver from scrap segments.

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