Recovery of Neodymium as (Na, Nd)(SO4)2 from the Ferrous Fraction of a General WEEE Shredder Stream

S Peelman,Y Yang,J Sietsma

doi:10.1007/s40831-018-0165-5

S Peelman, Y Yang + Show 1 more

Open Access

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

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Abstract

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%.

Highlights

The rare earth elements or REEs are a collection of 17 chemical elements [15 lanthanides plus yttrium (Y) and scandium (Sc)], which are becoming increasingly important in modern-day technology
To achieve an oxidation of more than 90%, the Waste Electrical and Electronic Equipment’’ (WEEE) should be stirred in water for 24 h at 80 °C while providing an O2 supply of 40 L/h. (At industrial scale, air can be a viable alternative to O2.)
Nd can be successfully leached from the oxidized WEEE by supplying the minimal amount of H2SO4 that meets the stoichiometric requirements for dissolution of all nonferrous elements present in the upgraded ferrous WEEE

Summary

Introduction

The rare earth elements or REEs are a collection of 17 chemical elements [15 lanthanides plus yttrium (Y) and scandium (Sc)], which are becoming increasingly important in modern-day technology. With applications in electrical and electronic devices (e.g., capacitors, phosphors, and high-strength magnets), chemical industry (e.g., catalysts), and green energy (e.g., batteries and windmills) [1,2,3,4,5], they are an essential resource for many industries. To meet this increasing demand, the EU is entirely dependent on REE imports from China [6], as. Neodymium (Nd) is one of the most critical REEs that the EU wishes to recycle This element is a key component of Neodymium–Iron–Boron (NdFeB) high-strength magnets. A stable supply of Nd is crucial to ensure the future production and development of such applications within the EU

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