Due to their remarkable magnetic properties, such as a high maximum energy product, high remanence, and high coercivity, NdFeB magnets are used in a variety of technological applications. Because of their very limited recycling, high numbers of spent NdFeB magnets are widely available in the market. In addition to China’s monopoly on the supply of most rare earth elements, there is a need for the recovery of these critical metals, as their high import price poses an economic and environmental challenge for manufacturers. This paper proposes a pyrometallurgical recycling method for end-of-life NdFeB magnets by oxidizing them in air as first required step. The main goal of this method is to oxidize rare earth elements from NdFeB magnets in order to prepare them for the carbothermic reduction. The experimental conditions, such as the oxidation temperature and time, were studied in order to establish the phase transformation during oxidation using the Factsage Database and experimental conditions. Our thermogravimetric analysis TGA analysis revealed an increased sample mass by 35% between room temperature and 1100 °C, which is very close to the total calculated theoretical value of oxygen (36.8% for all elements, and only 3.6% for rare earth elements REE), confirming the complete oxidation of the material. The obtained quantitative analysis of the oxidation product, in (%), demonstrated values of 53.41 Fe₂O₃, 10.37 Fe₃O₄; 16.45 NdFeO₃; 0.45 Nd₂O₃, 1.28 Dy₂O₃, 1.07 Pr₂O₃, and 5.22 α-Fe.

This paper proposes a pyrometallurgical recycling method for end-of-life NdFeB magnets by oxidizing them in air and subsequently smelting them. The smelting process enabled the recovery of rare earth elements (REEs), producing a new reach concentrate separating the iron as a metallic phase. From the products of smelting, the metallic phase showed a maximum Fe content of 92.3 wt.%, while the slag phase showed a maximum total REE (Nd, Pr, and Dy) content of 47.47 wt.%, both at a smelting temperature of 1500 °C. ICE-OES and XRD analysis were conducted on both phases, and results showed that the metal phase consists mainly of Fe and Fe₃C while the slag phase consists of the RE-oxides, leftover Fe₂O_3, and a mixture of Fe₆Nd_4. The obtained slag concentrate based on the oxides of rare earth elements is suitable for further pyrometallurgical or hydrometallurgical treatment in order to obtain rare earth elements.

The results obtained from the work on a concept of a recycling process for NdFeB magnets to recover rare earth elements for remanufacturing similar magnets are presented. This paper investigates the viability of extracting rare earth metals from magnet recycling-derived oxide (MRDO) by means of molten salt electrolysis. The MRDO was produced from spent NdFeB magnets through oxidation in air and subsequently carbothermic reduction under an 80 mbar Ar gas atmosphere. This MRDO contained roughly 33 wt.% Nd and 10 wt.% Pr. The electrochemical reduction process of the MRDO on molybdenum electrodes in NdF₃ + LiF and NdF₃ + PrF₃ + LiF fused salts systems was investigated by cyclic voltammetry and chronoamperometry measurements. The resulting electrolytes and electrodes were examined after potentiostatic deposition by scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), and X-ray diffraction (XRD) analysis. The electrodeposited metals appeared to accumulate on the cathode and X-ray diffraction analysis confirmed the formation of metallic Nd and Pr on the working substrate. The suitability of the obtained alloy intended for the remanufacturing of NdFeB magnets was then evaluated.

In the recycling of semiconductor materials like Bi₂Te₃ or CdTe, TeO₂ may form as a by-product that can be directly reduced to recover metallic Te. The hydrogen reduction of TeO₂ offers an eco-friendly alternative to conventional carbothermic reduction by avoiding CO by-products. This study investigates the reduction of 99.99 wt.% purity level TeO₂ using hydrogen in an oscillating kiln furnace (200–800 °C, 2–7 h), with phase composition and microstructure analysed via XRD and SEM. Results demonstrate conversions of up to 89% (solid–gas) and 100% (liquid–gas), revealing that kinetics dominate over thermodynamics in controlling reaction progress. The work proposes a reaction mechanism based on morphological evolution observed in SEM images, suggesting that further parameter optimisation could enhance scalability. As the first lab-scale demonstration of hydrogen-assisted TeO₂ reduction, this study establishes a preliminary process window (temperature/time) and underscores the potential for industrial adoption. Future work should verify the proposed mechanism and refine operational parameters to maximize efficiency.

This study presents the development and evaluation of a novel solid–gas reactor designed to enhance the hydrogen reduction kinetics of tellurium oxide (TeO₂) under atmospheric pressure. Such gas–solid reactions can be processed in several types of reactors, including but not limited to fixed-bed reactors, moving-bed reactors, and fluidised-bed reactors. A combination of computational fluid dynamics (CFD) and experimental validation was employed to design and optimise a reactor’s geometry and gas-flow distribution. Single-phase CFD simulations were performed using the k–ω SST turbulence model to examine gas-flow behaviour, temperature uniformity, and gas-flow dead zones for two lance designs. The modified lance produced a stable swirling flow that improved gas distribution and eliminated stagnation regions. Experimental trials confirmed the simulation outcome in optimised gas-flow: the redesigned reactor achieved up to 65% conversion after 1 h and 70% after 2 h, a marked improvement over the rotary kiln, which required 5–6 h to reach similar levels. However, excessive gas flow led to cooling effects that reduced conversion efficiency. These results demonstrate the effectiveness of integrated CFD-guided reactor design for accelerating hydrogen-based oxide reduction and advancing sustainable metallurgical processes.