Abstract:Indium is a high-quality rare and precious metal element. When its purity reaches 99.999% (5N), it is referred to as high-purity indium. High-purity indium exhibits significantly superior performance, stability, and controllability compared to industrial-grade indium, making it highly valuable in advanced fields such as electronic chips and national defense. This paper provides a comprehensive review of various available technologies for the preparation and purification of high-purity indium, along with the latest research progress. The advantages and disadvantages of key methods, including solvent extraction, ion exchange, electrolysis, zone melting, distillation, and adsorption, are critically analyzed. Solvent extraction offers advantages such as energy efficiency and operational convenience, but it requires extensive use of organic solvents and acidic solutions, posing challenges in wastewater treatment and environmental pollution. Ion exchange is widely applied due to its reusability and ease of regeneration; however, its complex preparation technology, high equipment requirements, and elevated costs limit its broader adoption. Future reductions in production costs could significantly enhance its prospects. Electrolysis features simple equipment, environmentally friendly operation, and straightforward procedures, enabling both impurity separation and direct reduction of metal ions via electrons. Nevertheless, its long production cycles, high energy consumption, and the need for post-treatment of electrolyte waste remain drawbacks. Zone melting is highly efficient, energy-saving, and environmentally benign, with a simple and controllable process, yet it demands high-purity raw materials and exhibits limited effectiveness in purifying impurities with partition coefficients close to 1. Distillation is pollution-free and operationally simple but suffers from low efficiency, high equipment and energy costs, and potential generation of hazardous substances during high-temperature processes. Beyond improving existing technologies and optimizing core process parameters, future advancements in high-purity indium purification urgently require the integration of artificial intelligence and the exploration of industrialized pathways for advanced purification techniques.
