Unveiling the mechanisms of critical and high-value metals extraction from secondary resources via molten salt electrolysis: a review.

Abstract

With the rapid growth in demand for critical metals in industries such as energy storage and advanced materials, secondary resources are increasingly emerging as promising alternatives to primary raw materials. Traditional methods for extracting metals from secondary resources often face limitations in dealing with complex compositions and harsh processing conditions. Molten-salt electrolysis has shown considerable potential for the recovery of a wide range of metals from various secondary resources, owing to its advantages in high-temperature ionic environments, efficient mass transport, and direct electrochemical conversion. However, a systematic understanding of reaction pathways and mechanisms remains limited. Existing studies also lack comprehensive analyses of coupled electrochemical, structural, and interfacial processes governing metal extraction. Therefore, considering their potential as inexpensive and readily available sources of critical metals, this review evaluates various industrial and mineral processing wastes-including metal/alloy waste, coal ash, and other secondary resources. This review analyzes spectroscopic characterization, theoretical simulations, and reaction mechanisms to advance extraction technologies and address key challenges. The environmental implications of molten-salt electrolysis are also evaluated through life cycle assessment, providing further insight into its environmental performance and potential for large-scale application.

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