Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2026/r/gumushane/16329
  Selective extraction of rare earth elements from end-of-life NdFeB magnets via low-temperature NH4Cl-based chlorination roasting and water leaching

  Kumas, Cavit; Prasetia, Hendra; Sumardi, Slamet; Astuti, Widi; Mufakhir, Fika Rofiek; Daulay, Amru; Wicaksono, Mahruri Arif

  Neodymium-iron-boron (NdFeB) magnets are critical components in the transition to a low-carbon energy economy due to their superior magnetic properties. They have significantly higher rare earth element (REE) content (25-35%) compared to natural resources (0.15-2%), making end-of-life NdFeB magnets a valuable secondary REE source. In this study, the selective recovery of REEs from end-of-life NdFeB magnets was investigated using water leaching following chlorination roasting with NH4Cl. A series of experiments was conducted to evaluate the effect of NH4Cl on the NdFeB magnet ratio, roasting temperatures, and roasting duration. Under optimal conditions (300 degrees C, 3 h, NH4Cl at twice the stoichiometric requirement), the roasted products were subjected to water leaching (500 rpm, 90 degrees C, liquid - solid ratio of 20 mL/g, 1 h). resulting in over 95% REE dissolution. Rare earth oxalates were precipitated from the pregnant leach solution with 90% efficiency using 1.5 times the stoichiometric requirement of oxalic acid. Subsequent calcination at 850 degrees C for 2 h yielded rare earth oxides with 99.8% REE purity. Moreover, the dissolution of iron was effectively suppressed through a simple two-stage Fe(OH)3 precipitation step, providing a more economical and selective recovery route. Les aimants de n & eacute;odyme-fer-bore (NdFeB) sont des composants critiques de la transition vers une & eacute;conomie & eacute;nerg & eacute;tique & agrave; faible carbone gr & acirc;ce & agrave; leurs propri & eacute;t & eacute;s magn & eacute;tiques sup & eacute;rieures. Ils ont une teneur en & eacute;l & eacute;ments de terres rares (ETR) sup & eacute;rieures (25-35%) aux ressources naturelles (0.15-2%), ce qui rend les aimants de NdFeB en fin de vie une source secondaire pr & eacute;cieuse d'ETR. Dans cette & eacute;tude, on a examin & eacute; la r & eacute;cup & eacute;ration s & eacute;lective des ETR des aimants de NdFeB en fin de vie par lixiviation aqueuse apr & egrave;s grillage chlorurant avec du NH4Cl. On a effectu & eacute; une s & eacute;rie d'exp & eacute;riences pour & eacute;valuer l'effet du rapport NH4Cl/aimant de NdFeB, des temp & eacute;ratures et de la dur & eacute;e de grillage. Dans des conditions optimales (300 degrees C, 3 h et une concentration de NH4Cl deux fois sup & eacute;rieure & agrave; la st oe chiom & eacute;trie requise), on a soumis les produits grill & eacute;s & agrave; une lixiviation aqueuse (500 tr/min, 90 degrees C, rapport liquide/solide de 20 mL/g, 1 h) conduisant & agrave; une dissolution de plus de 95% des ETR. On a pr & eacute;cipit & eacute; les oxalates de terres rares & agrave; partir de la solution de lixiviation enrichie avec une efficacit & eacute; de 90% en utilisant 1.5 fois la quantit & eacute; st oe chiom & eacute;trique requise d'acide oxalique. Une calcination ult & eacute;rieure & agrave; 850 degrees C pendant 2 h a produit des oxydes de terres rares d'une puret & eacute; de 99.8%. De plus, la dissolution du fer & eacute;tait efficacement supprim & eacute;e par une simple & eacute;tape de pr & eacute;cipitation de Fe(OH)3 en deux phases, offrant une voie de r & eacute;cup & eacute;ration plus & eacute;conomique et plus s & eacute;lective.

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• MakaleYalnız künye2026/r/gumushane/16243
  An 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.

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