Konferans 2020-2029 yılları

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Browsing Konferans 2020-2029 yılları by Subject "Molten salt electrolysis"

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    Production of Metallic Lanthanum from Its Oxide Form via Molten Salt Electrolysis
    (Türkiye Enerji, Nükleer ve Maden Araştırma Kurumu (TENMAK), 2024-04-26) Özer, Osman Can; Arslan Kaba, Mehtap; Kartal Şireli, Güldem; Soydaş Sözer, Belma; Timur, Servet
    Lanthanides, including the elements with the atomic number of 57 to 71, scandium, and yttrium are the seventeen chemically related elements known as rare earth elements (REEs). Despite their misleading name, “rare earth”, these elements are not rare in the Earth’s crust. Instead, the term refers to the challenge of separating and obtaining them in their pure form due to their similar chemical properties. REEs are crucial in a variety of high-technology applications, namely the military, the automobile industry, electrical engineering, optics, catalysts, wind turbines, and other sustainable energy systems, due to their exceptional physical and chemical properties. Because of the growing demand for REEs in functional materials, the recovery of REEs from secondary resources has become critical to the transition to a green economy. The primer REEs extraction process consists of mining, physical beneficiation, chemical treatments, separation, and reduction. In the reduction step, where REEs reduce to metal form, electrolytic methods (molten salt electrolysis) and metallothermic methods are prominently discussed in the open literature. Electrolytic methods can operate continuously and outperform metallothermic techniques in terms of production capacity and controllability, as well as product purity. Nowadays, two types of electrolytes are commonly used in the electrolytic production of REEs: fluoride- and chloride-based molten salts. The main issues with the widely used electrochemical extraction of rare earth oxides in fluoride-based molten electrolytes are lower solubility and lower energy efficiencies, as well as higher emissions of greenhouse gases, such as CO2 and perfluorocarbons, which are extremely harmful to the environment. Given the current limitations of fluoride systems, molten chloride-based electrolytes appear to be a preferable option. To achieve lower melting points (e.g., 650 °C) and higher product purities (i.e., 99%), common chloride electrolytes are composed of RECl3 (RECl3= rare earth chlorides) and additional chlorides, such as NaCl, KCl, BaCl2, and CaCl2. Thus, we concentrated on molten salts based on chlorides containing RECl3. To overcome the low solubility of rare earth oxides in molten chloride salts and toxic oxychloride formations, RECl3 salts were used. RE2O3 was converted to RECl3 in a separate system through chlorination. Furthermore, the need to work in a controlled atmosphere due to REEs high oxygen affinity made the electrolysis cell design critical. As a result, the electrochemical cell was designed and installed, and the effects of process parameters such as electrolyte composition, temperature, current efficiency, and electrolysis time were investigated systematically. X-ray diffractometry (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) were used to characterize the produced La. The maximum current efficiency was found to be 73.5%. These obtained results could potentially be implemented during the development of domestic technology for the electrolytic extraction of REEs from Turkey Eskişehir Beylikova REEs ores.