A Review and Future Development of Chlorination Treatment Technology for Metallurgical Slag

Metallurgical slag, as the primary solid waste of the metallurgical industry, is rich in valuable metal components such as iron, copper, titanium, and rare earth elements. Chlorination treatment technology has demonstrated remarkable application potential in the resource utilization of typical slag types such as copper slag, titanium slag, and rare earth slag due to its high selectivity and suitability for medium- to low-temperature operations. This paper systematically reviews the thermodynamic and kinetic mechanisms of the chlorination process, focusing on the effects of chlorination agent types, reaction temperature, atmospheric conditions, additives, and slag characteristics on chlorination efficiency. On this basis, it elaborates on the research progress in selective chlorination, chlorination roasting, molten chlorination, and chlorination-condensation combined processes for extracting valuable metals such as titanium, lithium, zinc, and lead, as well as removing impurities like calcium, magnesium, and silicon. Typical application cases, including copper extraction from copper slag, titanium recovery from titanium slag, and lithium recovery from lithium slag, are covered. Additionally, methods for product separation and purification, such as graded condensation, distillation, and recrystallization, are summarized, along with resource utilization pathways for tail gas and residues. The current status of harmful gas control, waste residue stabilization, and the development of clean processes is discussed. Finally, future research directions are anticipated, including intelligent process control, coupled process development, and green low-carbon transformation, aiming to provide a scientific basis and technical reference for the efficient recycling of metallurgical slag.