Application of electromagnetic fields in separation, purification, refining, and crystal growth processes of metallic materials: A review

The application of electromagnetic fields in materials separation, refining, and purification processes has emerged as a powerful strategy for achieving high-purity crystalline materials and enhancing electrochemical performance. This review comprehensively examines the role of steady (vertical, horizontal, cusp) and non-steady (rotating, alternating, traveling) magnetic fields in controlling melt convection during bulk crystal growth, zone refining, melt purification and electrolytic refining. In crystal growth techniques such as Czochralski, vertical Bridgman, and floating zone methods, magnetic fields suppress turbulent flow, stabilize thermal transport, and improve dopant and impurity distribution. They enable precise control over defect densities and segregation behavior, critical for semiconductor-grade materials. In zone refining, electromagnetic stirring enhances impurity segregation kinetics, while container-free techniques like electromagnetic suspension minimize contamination. In melt purification, magnetic fields have shown high efficacy in purifying molten metals by removing non-metallic inclusions. In electroslag remelting, external magnetic fields refine droplets, shallow metal pools, and reduce segregation. For electrolytic refining, magnetic fields induce Lorentz force and Kelvin force, improving mass transport, reducing concentration polarization, and modifying deposit morphology. Notably, gradient magnetic fields exploit differences in magnetic susceptibility for selective separation of rare earth ions and organometallic compounds, achieving high-purity enrichment through crystallization and precipitation strategies. The integration of hybrid field configurations and advanced numerical models further optimizes process efficiency and material homogeneity. These advancements underscore the broad utility of electromagnetic fields in enabling next-generation materials purification, with applications spanning semiconductors, metals, and critical rare earth elements. Future efforts should focus on real-time control and scalability for industrial adoption.