Recovery of neodymium as (Na, Nd)(SO4)2 from the ferrous fraction of a general WEEE shredder stream

Recovery of neodymium as (Na, Nd)(SO4)2 from the ferrous fraction of a general WEEE shredder stream

Peelman, S. (TU Delft (OLD) MSE-3)
Sietsma, J. (TU Delft Materials Science and Engineering; TU Delft (OLD) MSE-3)
Yang, Y. (TU Delft (OLD) MSE-3)

Materials Science and Engineering

2018

Neodymium is a critical element used in many high-tech applications. However, despite this, the EU is entirely dependent on China for its Nd supply. This has driven the EU to develop recycling strategies to recover its Nd from end-of-life (EoL) products and wastes, and establish a domestic supply. This paper proposes a process to recycle Nd from NdFeB magnet particles present in the ferrous fraction of shredded “Waste Electrical and Electronic Equipment” (WEEE), after physical upgrading. This WEEE fraction represents a waste stream that has not been previously considered a source of Nd. A three-step process was developed. First, the upgraded ferrous WEEE fraction is oxidized by means of water corrosion. Second, the oxidized WEEE is leached with diluted H2SO4 to selectively extract Nd and other nonferrous elements. And finally, the leach liquor is treated with Na2SO4 to precipitate the Nd as its double sulfate (Nd, Na)(SO4)2. The oxidation process oxidizes 93% of the metallic iron to Fe(OH)3, leaving 7% of the iron unoxidized. The leaching process dissolves between 70 and 99% of the Nd, depending on the temperature and liquid/solid ratio (L/S); this is accompanied by an iron coextraction between 9 and 20%. The precipitation recovers 92% of the leached Nd. The purity of the obtained precipitates is dependent on the pH at which the precipitation takes place. A pH below 0.5 is required to prevent Fe contamination, and a pH below 0 reduces the Ca contamination to below 1 wt%. The developed process provides an effective and low-cost method to recycle Nd from a shredded WEEE stream with an overall Nd recovery of over 90%.

WEEE recycling
Neodymium
Rare earth elements
Secondary resources
Rare earth recycling

http://resolver.tudelft.nl/uuid:7be16c7f-8c03-4f39-a319-c6e60ea0a9a6

https://doi.org/10.1007/s40831-018-0165-5

Journal of Sustainable Metallurgy, 4 (2), 276-287

Institutional Repository

journal article

© 2018 S. Peelman, J. Sietsma, Y. Yang