Hydrometallurgical recycling of waste NdFeB magnets: design of experiment, optimisation of low concentrations of sulphuric acid leaching and process analysis

Emircan Uysal; Serhat Al; Elif Emil-Kaya; Srecko Stopic; Sebahattin Gürmen; Bernd Friedrich

doi:10.1080/00084433.2022.2058152

Hydrometallurgical recycling of waste NdFeB magnets: design of experiment, optimisation of low concentrations of sulphuric acid leaching and process analysis

Emircan Uysal, Serhat Al, Elif Emil-Kaya, Srecko Stopic, Sebahattin Gürmen^*, Bernd Friedrich

^*Corresponding author for this work

Department of Metallurgical and Materials Engineering

Research output: Contribution to journal › Article › peer-review

14 Citations (Scopus)

Abstract

Efficient recovery of rare earth elements (REEs) from scrap NdFeB magnets is a significant requirement for a circular economy. Therefore, the development of a cost-effective and environmentally friendly leaching process for the dissolution of iron and REEs has received extensive interest. In this study, the dissolution of NdFeB magnet powders in sulphuric acid solution was investigated in detail. Taguchi orthogonal array was employed for the first time to define and optimise the influence of sulphuric acid concentration, solid-to-liquid ratio and stirring speed on the extraction of iron and rare earth elements (REEs). The acid concentration of sulphuric acid was determined as a key factor for iron and REEs dissolution, while solid-to-liquid ratio and stirring speed slightly affected the dissolution of REEs and iron. Maximum iron and REEs extraction were achieved under optimal conditions as the sulphuric acid concentration of 1 M, solid-to-liquid ratio of 1/15 and stirring speed of 350 rev min⁻¹. Consequently, after the validation experiment, it was proved that the design of experiments based on Taguchi orthogonal array is an efficient way for the optimisation of process parameters.

Original language	English
Pages (from-to)	107-118
Number of pages	12
Journal	Canadian Metallurgical Quarterly
Volume	62
Issue number	1
DOIs	https://doi.org/10.1080/00084433.2022.2058152
Publication status	Published - 2023

Bibliographical note

Publisher Copyright:
© 2022 Canadian Institute of Mining, Metallurgy and Petroleum.

Funding

The research leading to these results has received funding from the German Federation of Industrial Research Associations, Germany and TÜBITAK - Scientific of Technological Research Council of Turkey (Call identifier CORNET 29th Call) under grant agreement EN03193/20. The authors would like to greatly acknowledge TUBITAK/Turkey (Project No: 120N331) for financial support. The authors would like to thank Professor Dr. Gültekin Göller, technician Hüseyin Sezer for the SEM-EDS analysis, and also, Professor Dr. Bora Derin and Research Assistant Faruk Kaya for FactSage calculations.

Funders	Funder number
TUBITAK/Turkey	120N331
Allianz Industrie Forschung
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu	EN03193/20

Keywords

design of experiment
Leaching
NdFeB magnets
rare earth elements
Taguchi method

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10.1080/00084433.2022.2058152

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abstract = "Efficient recovery of rare earth elements (REEs) from scrap NdFeB magnets is a significant requirement for a circular economy. Therefore, the development of a cost-effective and environmentally friendly leaching process for the dissolution of iron and REEs has received extensive interest. In this study, the dissolution of NdFeB magnet powders in sulphuric acid solution was investigated in detail. Taguchi orthogonal array was employed for the first time to define and optimise the influence of sulphuric acid concentration, solid-to-liquid ratio and stirring speed on the extraction of iron and rare earth elements (REEs). The acid concentration of sulphuric acid was determined as a key factor for iron and REEs dissolution, while solid-to-liquid ratio and stirring speed slightly affected the dissolution of REEs and iron. Maximum iron and REEs extraction were achieved under optimal conditions as the sulphuric acid concentration of 1 M, solid-to-liquid ratio of 1/15 and stirring speed of 350 rev min−1. Consequently, after the validation experiment, it was proved that the design of experiments based on Taguchi orthogonal array is an efficient way for the optimisation of process parameters.",

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AU - Friedrich, Bernd

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Hydrometallurgical recycling of waste NdFeB magnets: design of experiment, optimisation of low concentrations of sulphuric acid leaching and process analysis

Abstract

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