| Summary: | Nowadays the scarcity of rare earths is a problem of significant importance due to the
indispensable role of Nd-Fe-B permanent magnets in numerous technological
applications. The international reliance on rare earth elements and the costly
manufacturing processes involved in producing these magnets pose today both
environmental and economic challenges. As the demand for rare earth permanent magnets
grows, concerns about resource scarcity, energy consumption, and waste accumulation
become more pressing.
Developing new recycling routes for Nd-Fe-B permanent magnets is crucial to address
these challenges. By establishing efficient methods to recover and reuse rare earth
containing elements from discarded or obsolete devices could significantly reduce the
need for mining new resources, helping to mitigate the environmental impact associated
with mining and processing.
For that reason, the problem of permanent magnets underscores the necessity of finding
alternative and sustainable ways to produce, utilize, and recover these crucial materials.
The development of novel recycling routes is a key step towards addressing the challenges
posed by resource scarcity, environmental concerns, and economic fluctuations,
contributing to a more sustainable future, and creating new business opportunities in the
green technology sector.
This PhD thesis aims to study new recycling routes for rare earth magnets, based on the
use of gas atomization technique to melt scrap magnets and produce Nd-Fe-B recycled
powders. This powder can be used to manufacture a new magnet. Gas atomization is a
highly interesting industrial production technique with numerous advantages, including
high productivity and lower cost compared to other production techniques.
The limitation of the gas-atomized powders lies in their low magnetic properties. For that
reason, with the aim to enhance their magnetic properties, different alternatives of heat
treatments and reactions in hydrogen atmosphere such as hydrogen decrepitation (HD)
and the hydrogenation-disproportionation-desorption-recombination (HDDR)
process will be analyzed. Moreover, the effect of some commonly used additives in Nd-
Fe-B permanent magnets, such as Nb and Ga will be analyzed. The ultimate motivation
is to enhance their magnetic properties, transforming them into a useful material to
produce both isotropic and anisotropic bonded magnets.
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