Hydrometallurgical Recovery of Rare Earth Fluorides from Recycled Magnets and Process Optimization

Minerals

卷:10

Prince Sarfo¹  Avimanyu Das¹  Thomas Frasz¹  Courtney Young¹ 

[1] Metallurgical and Materials Engineering, Montana Tech, 1300 West Park Street, Butte, MT 59701, USA;

关键词: rare earth elements;    magnets;    recycling;    recovery;    fluorides;    modelling;   

DOI  :  10.3390/min10040340

来源: DOAJ

【 摘 要 】

Magnets containing substantial quantities of rare earth elements are currently one of the most sought-after commodities because of their strategic importance. Recycling these rare earth magnets after their life span has been identified to be a unique approach for mitigating environmental issues that originate from mining and also for sustaining natural resources. The approach is hydrometallurgical, with leaching and precipitation followed by separation and recovery of neodymium (Nd), praseodymium (Pr) and dysprosium (Dy) in the form of rare earth fluorides (REF) as the final product. The methodology is specifically comprised of sulfuric acid (H₂SO₄) leaching and ammonium hydroxide (NH₄OH) precipitation followed by reacting the filtrate with ammonium bifluoride (NH₄F·HF) to yield the REF. Additional filtering also produces ammonium sulfate ((NH₄)₂SO₄) as a byproduct fertilizer. Quantitative and qualitative evaluations by means of XRD, ICP and TGA-DSC to determine decomposition of ammonium jarosite, which is an impurity in the recovery process were performed. Additionally, conditional and response variables were used in a surface-response model to optimize REF production from end-of-life magnets. A REF recovery of 56.2% with a REF purity of 62.4% was found to be optimal.

【 授权许可】

Unknown