Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2026Aluminum Recovery and Process Optimization from High-Silica Kemiklitepe (Türkiye) Bauxite Ore by the Alkaline Roasting-Water Leaching Method
Uysal, Turan
In this study, an innovative and environmentally friendly alternative method was investigated for aluminum recovery from diasporic bauxite, classified as a critical raw material, without using caustic soda. Within this context, the alkaline roasting–water leaching combination was applied to enhance aluminum recovery from high-silica bauxite ore. Optimization of the process parameters was carried out using Response Surface Methodology (RSM). The effects of key parameters, roasting temperature, milling time, and ball-to-powder/ore ratio (BPR), on Aluminum (Al) dissolution were systematically evaluated through the RSM design. The reliability of the model was confirmed by ANOVA analysis, and the regression results indicated that the coefficient of determination (R²) exceeded 90% for all responses, demonstrating a strong model fit. According to the optimization outcomes, the optimum conditions were determined as a roasting temperature of 919 °C, a milling time of 90 minutes, and a BPR of 23. Water leaching results revealed that aluminum recovery increased by approximately 26% in the ore roasted at 1000 °C compared to the raw (unroasted) ore. Overall, the findings indicate that the alkaline roasting–water leaching method is a promising alternative for processing high-silica bauxite deposits.
- MakaleYalnız künye2026An integrated process for rare earth elements recovery and silica production from Turkish bauxite-related ores
Uysal, Turan; Erüst, Ceren; Erdemoglu, Murat; Sis, Hikmet
The 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.
- MakaleAçık Erişim2026Hydrometallurgical 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.
- MakaleAçık Erişim2026Solvent extraction of rare earth elements and α-alumina production from pregnant leaching solution obtained from Turkish bauxite-related ore
Erust, Ceren; Uysal, Turan
The use of bauxite-related shales as a secondary source for the extraction of rare earth elements (REEs) is very important to meet the raw material supply, which is the keystone of advanced technology applications. This study presents the investigation into the recovery of REEs from Kızıldağ shale ore and the potential utilization of its leach residue as a silica source. Mineralogical analysis revealed that the ore predominantly consists of paragonite, muscovite, quartz, pyrophyllite, and calcite. Calcined ore was subjected to acid leaching, and the resulting pregnant solution was purified using solvent extraction to separate from aluminum the ∑REEs with a content of 1887.35 ppm. Optimal solvent extraction conditions 1.5 M D2EHPA, 50% O/A ratio, pH 1.5, and 15-minute mixing time achieved 95% total REE extraction, with efficiency in the order Pr > La > Nd > Ce > Dy > Y > Sc. To purify Al from the Fe- and K-rich solution post-SX, electrolysis was performed, resulting in 97.16% precipitation efficiency of Al as Al(OH)3 at pH 5. The precipitate was subsequently roasted at 1100°C to produce α-alumina with 75.2% Al2O3 content. These findings confirm the technical feasibility of recovering REEs and producing coarse-purity alumina from Kızıldağ shale ore.
- MakaleYalnız künye2026Assessment of gamma-ray attenuation properties in advanced ceramics incorporating colemanite, pyrophyllite, and plastic clay
Uysal, Turan; Kaya, Selim
This study investigates the gamma-ray and neutron shielding performance of advanced ceramic composites containing colemanite, pyrophyllite, and plastic clay as environmentally friendly alternatives to conventional lead-based shielding materials. Gamma-ray attenuation properties were evaluated over the energy range of 59.54–2000 keV using theoretical calculations from WinXCOM and Monte Carlo simulations performed with the EGS4 code. Excellent agreement between the two methods confirmed the reliability of the simulation results. The mass attenuation coefficient (μ/ρ) decreased with increasing photon energy due to the transition from photoelectric absorption to Compton scattering and pair production mechanisms. Correspondingly, the half-value layer (HVL) and mean free path (MFP) increased, while radiation protection efficiency (RPE) decreased with photon energy. The effective atomic number (Zeff) exhibited an energy-dependent decline, reflecting changes in dominant photon–matter interaction processes. Neutron shielding performance improved with increasing colemanite content owing to the presence of boron-rich phases, and Sample-5 exhibited the highest fast neutron removal cross-section (ΣR = 0.11062 cm−1). The same sample also showed the highest gamma-ray kerma coefficients, indicating enhanced energy absorption capability. Overall, the results demonstrate that colemanite-enriched ceramic composites provide effective combined gamma-ray and neutron shielding and represent promising, sustainable, and non-toxic alternatives for radiation protection applications.
- MakaleYayıncıda açık erişim2025Optimization of rare earth elements recovery from Kızıldag (Karaman-Türkiye) shale ore using response surface methodology
Uysal, Turan; Ünal, Ceren Erust; Akça, Muhammet Esat; Sis, Hikmet; Erdemoğlu, Murat
In 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, Kızıldag (Karaman-Türkiye) 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, three-dimensional 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.
- MakaleAçık Erişim2024Economic Evaluation of Thermal and Mechanical Activation Energies in Plaster Production
Şener, Muhammed; Uysal, Turan; Erdemoğlu, Murat
Plaster is among the most needed raw materials in the world. In this study, thermal activation provided by calcination and mechanical activation methods provided by intensive milling in the plaster production process were evaluated in terms of activation energy. In this context, the energies of laboratory-scale thermal and mechanical activation processes were calculated and these activation methods were evaluated economically and the ideal activation methods were determined. Although the mechanical activation method creates additional investment and operating costs, it reduces the calcination temperature by 13 °C, thus provides lower energy costs. Addition of a mechanical activator mill before thermal activation in plaster production as a more economical and more environmentally friendly method was proposed.