In a recent review article published in the journal Minerals, researchers addressed the pressing issue of rare-earth element (REE) depletion and the potential for recycling these valuable resources from waste phosphors.
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The need for sustainable extraction methods becomes increasingly urgent as the demand for REEs continues to rise due to their critical applications in various high-tech industries. This article provides a comprehensive overview of the current methodologies for extracting and separating REEs from waste phosphors, particularly those derived from fluorescent lamps, while also discussing the advantages and limitations of these techniques.
Background
Rare-earth elements (REEs) consist of 17 elements, including lanthanides and yttrium, which are essential for numerous technological applications.
The increasing consumption of REEs has led to significant depletion of primary resources, prompting researchers and industries to explore alternative sources for these elements.
Waste phosphors, particularly those from discarded fluorescent lamps, represent a substantial reservoir of REEs. However, improper disposal results in environmental pollution and the loss of valuable resources.
Studies Highlighted in This Review
The article systematically reviews various studies investigating the extraction and separation of REEs from waste phosphors, categorizing the methods into physical and chemical techniques.
Physical methods include magnetic separation, flotation, and adsorption. Magnetic separation exploits the magnetic properties of certain materials to isolate REEs, while flotation utilizes differences in surface properties to separate valuable components from waste.
Adsorption techniques involve using materials that selectively bind to REEs, allowing their recovery from complex mixtures. Although these physical methods are generally more environmentally friendly and require fewer chemical inputs, they often lower purity and recovery rates.
On the other hand, chemical methods are further divided into acid leaching, alkaline fusion, solvent extraction, and external field-enhanced methods.
Acid leaching involves using strong acids, such as hydrochloric or sulfuric acid, to dissolve REEs from waste phosphors. This method has shown significant recovery rates but raises concerns regarding the generation of hazardous waste.
Alkaline fusion methods utilize alkaline agents, such as sodium hydroxide, to enhance the extraction of REEs, but they can be energy-intensive and complex. Solvent extraction techniques enable the selective separation of individual REEs but often involve toxic solvents that pose environmental risks.
External field-enhanced methods, including microwave and ultrasound-assisted techniques, have emerged as promising approaches to improving extraction efficiency. However, they also require substantial energy input.
The authors highlight several key studies that have contributed to understanding these extraction methods. For instance, research has demonstrated the effectiveness of combining physical and chemical techniques to optimize the recovery of REEs from waste phosphors. Researchers have enhanced recovery rates and product quality by employing physical methods for initial concentration followed by chemical methods for purification.
Results and Discussion
The article thoroughly analyzes the results obtained from various studies on the extraction and separation of REEs from waste phosphors.
The authors emphasize that while physical methods are simpler and more environmentally friendly, they often yield products with lower purity and performance. This limitation makes them suitable primarily for the preliminary concentration of REEs. In contrast, chemical methods, particularly acid leaching and solvent extraction, demonstrate higher recovery rates but have significant environmental and operational challenges.
The authors argue that integrating physical and chemical methods could enhance the overall efficiency of REE recovery from waste phosphors. For example, using physical methods for initial concentration followed by chemical methods for purification could optimize resource recovery while minimizing environmental impact.
Moreover, the review underscores the importance of addressing the challenges associated with current extraction methods, such as high costs, environmental pollution, and process complexity. The authors advocate for the exploration of innovative approaches, including the use of biotechnological methods and the development of novel materials for adsorption and separation, to improve the sustainability of REE recovery from waste phosphors.
Conclusion
In conclusion, the review article provides a comprehensive overview of the current state of research on the extraction and separation of rare-earth elements from waste phosphors.
The authors emphasize the critical need for efficient recycling methods to mitigate the depletion of primary REEs and reduce environmental pollution associated with waste disposal.
While various physical and chemical methods have been developed, each presents its own set of advantages and limitations.
The authors recommend a combined approach that leverages the strengths of physical and chemical techniques to enhance recovery rates and product quality.
The findings of this study serve as a foundation for further research and development in rare-earth recycling, ultimately supporting the transition toward a more sustainable and circular economy.
Source:
Tian G., Xu Z., et al. (2025). Research Progress on the Extraction and Separation of Rare-Earth Elements from Waste Phosphors. Minerals 15(1), 61. DOI: 10.3390/min15010061, https://www.mdpi.com/2075-163X/15/1/61