Resource-oriented utilization of high-alkali metal sintering machine head dust： advances and outlook

Sintering machine head dust is one of the major solid wastes generated during iron and steel metallurgical processes. Its composition is dominated by iron, while also containing various impurity elements such as potassium, sodium, lead, and chlorine. These impurities originate from diverse sources and predominantly exist in the form of chloride salts agglomerated on or adhered to the surface of iron oxide particles. Currently, the treatment of sintering machine head dust has evolved into an integrated recovery process system centered on a combined flowsheet of "water leaching for alkali metal removal-returning iron-rich residue to sintering" and "leachate purification for impurity removal-evaporative crystallization for alkali metal salt recovery", supplemented by physical beneficiation and other methods to improve the quality of iron-rich residue. This comprehensive recovery process has been applied in some iron and steel enterprises. With the deepening of supply-side structural reform in the steel industry, enterprises have raised higher demands for the thorough removal of alkali metals, process simplification, and benefit enhancement. This paper starts with the source tracing of sintering machine head dust, followed by analysis of its physicochemical characteristics, elucidation of the formation, migration and conversion mechanisms of iron and key impurity components, and accordingly summarizes the existing recovery processes and innovative improvement directions. In response to the bottleneck issues commonly encountered in current treatment processes, such as poor universality, lengthy process, and valuable-component loss, a comprehensive strategy of "targeted regulation-quality-based treatment-refined recycling" is proposed. It is expected to offer a theoretical basis and technical references for efficient and high-value resource-oriented utilization of similar ferrous metallurgical dusts.