Advanced converter sludge utilization technologies for the recovery of valuable elements: A review

Due to the high proportion of the steel output produced by oxygen converter, significant quantities of converter sludge (CS) is generated annually as waste material. This study aims to review the latest CS utilization technologies and illuminate the migration behaviors of harmful substances as well as valuable elements. The intrinsic characteristics, including chemical constitution, size distribution, mineralogical composition, microstructure, and viscosity of the CS are studied. Migration behaviors of harmful substances are analyzed based on thermodynamic calculation. The results indicated that less eutectic mineral was found in CS, the iron oxides and other impurities like CaO, MgO and ZnFe₂O₄ mixed in the way of physical accumulation. The treatments through oxidation methods, such as iron ore sintering and oxidized pellets, are the most common and effective methods to recovery Fe in actual production. Due to the diverse physicochemical properties of CS from different enterprises, it is really difficult to choose one universal recovery method. In view of resources recovery and clean production, the authors believe that the best utilization technology at present is to prepare metallized pellets. It is regarded that technologies of preparing high value-added products, such as Li(FeM)PO₄ and iron powder are the most prospective methods in the future.