Synergistic utilization of multi-source solid waste in iron and steel industry: Toward sustainable resource recovery and urban metabolic symbiosis

Developing technologies for the valorization of urban and industrial wastes has become a critical strategy for promoting sustainable urban development and building a circular economy. This review systematically examines the process mechanisms, technological advances, and industrial practices of synergistic utilization of multi-source wastes within the main processes (coking, sintering, pelletizing, blast furnace, and steelmaking) and subsidiary processes (rotary kiln, rotary hearth furnace). It elucidates the material circulation pathways and energy conversion mechanisms of wastes within steel production. The study indicates that iron and steel manufacturing process, characterized by high temperatures, high energy density, and large-scale continuous operation, possess unique advantages in accommodating diverse wastes while facilitating resource recovery and energy integration. Such capabilities not only enable the harmless treatment and valorization of wastes but also allow by-products to feed back into urban development, fostering a closed-loop urban resource system. Despite these advantages, large-scale deployment of multi-source solid waste synergistic utilization in iron and steel manufacturing process still faces key challenges, including the generation and control of emerging pollutants, unclear migration mechanisms of impurity elements, insufficient tracking of cross-media pollutant transfer, unstable raw material supply chains, and the lack of life-cycle-oriented policy incentives. Looking forward, advancing fundamental research on pollutant formation and migration, developing multi-level source–process–end control strategies, constructing intelligent management systems based on full-process material flow tracking, and establishing cross-industry green supply chains with supportive policy mechanisms will strongly promote the transformation of the steel industry into an “urban metabolic hub,” providing systematic solutions for industrial green transition and urban resource circularity.