Rare-earth metals, particularly neodymium, dysprosium, and praseodymium are becoming increasingly important in the transition to a green economy due to their essential role in permanent magnet applications such as in electric motors and generators. With the increasingly limited rare-earth supply and complexity of processing Nd, Dy, and Pr from primary ores, recycling of rare-earth based magnets has become a necessary option to manage supply and demand. Depending on the form of the starting material (sludge or scrap), there are different routes that can be used to recover neodymium from secondary sources, ranging from hydrometallurgical (based on its primary production process), electrochemical to pyrometallurgical. Pyrometallurgical routes provide solution in cases where water is scarce and generation of waste is to be limited. This paper presents a systematic review of previous studies on the high-temperature (pyrometallurgical) recovery of rare earths from magnets. The features and conditions at which the recycling processes had been studied are mapped and evaluated technically. The review also highlights the reaction mechanisms, behaviors of the rare-earth elements, and the formation of intermediate compounds in high-temperature recycling processes. Recommendations for further scientific research to enable the development of recovery of the rare-earth and magnet recycling are also presented.

A tomographic study of electrochemical cells to observe scales formed on inert anodes has been conducted using energy‐dispersive synchrotron X‐ray diffraction. This study is preparatory to an investigation that will observe this formation in situ during the cells' operation. The purpose of the current work was to determine whether this technique would be appropriate for such a study in terms of its sensitivity and whether the results could be quantified satisfactorily. A method has been developed for the quantitative phase analysis of energy‐dispersive data using crystal‐structure‐based Rietveld refinement. This has been tested with standard materials and found to be comparable in accuracy to results obtained from traditional angular‐dispersive diffraction. The lower limits of detection of the method have not been established quantitatively but qualitative differences can be seen between cells that have been cycled at different times. These differences indicate a linear relationship between scale formation and electrolysis time.

Using the evolutionary optimization algorithm, as implemented in the USPEX crystal predictor program, and first principles total energy calculations, the compositional phase diagrams for Al-Sc and Al-Ta alloy systems at zero temperature and pressure have been calculated. In addition to the known binary intermetallic phases, new potentially stable alloys, AlSc3 and AlTa7, have been identified in the Al-poor region of the phase diagram. The dynamic and thermal stability of their lattices has been confirmed from the calculated vibrational normal mode spectra in the harmonic approximation.

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256ChemInform Abstract The electrochemical oxidation of (I) is studied at both mercury and platinum electrodes in CH2Cl2. Though the processes proceeding are different, the results show that the species (II) is a product common to oxidation at both electrodes. At a mercury electrode a specific reaction pathway leads to a quantitative reaction producing (II), whereas at platinum the formation of a highly reactive Hg(III)intermediate is proposed. On evaporation of solutions of (II), a solid compound (III) is isolated, which crystallizes in the space group P1 with Z=1. The molecular structure contains a polymeric chain with a repeating unit of five Hg atoms. One Hg is unique and six-coordinate, all the others are four-coordinate, there are no monodentate ligands. (III) redissolves in CH2Cl2 to give a mixture of(II) and (I).

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