Reourceful utilization of combustible solid wastes throughout steelmaking processes: Recent progress and prospects

The efficient consumption of combustible solid wastes (CSWs) is still a serious global problem due to the environmental pollution and energy waste brought by conventional disposal methods. Utilizing typical high-temperature kilns, including sintering machines, coke ovens and blast furnaces, throughout the whole steelmaking chain to consume CSWs on a large scale is a promising approach, which is characterized by energy recovering and volume reduction. This review systematically summarized the recent progress in the substitution of CSWs as renewable and recyclable alternative fuels, as well as addressing the limitations of these techniques and identifying opportunities for future research. Types, sources and resources of CSWs are introduced in this paper, which mainly include renewable biomass, recyclable carbon-rich wastes such as waste plastics and waste tires, municipal sludge, etc. The basic characteristics and utilization of typical CSWs are compared, and the combustion characteristics, application effects and enhancement technologies (pretreatment such as pre-dealkalization, pre-granulation and pre-melting, thermochemical conversion, optimization of fuel performance, sintering process parameters, and raw material structure, etc.) of different CSWs consumed in sintering machines, coking ovens and blast furnaces are discussed. For these high-temperature kilns, biomass is the most promising CSW, but its substitution ratio is still limited by combustion characteristics. Finally, a clear roadmap of specific next steps and priorities for research and development based on remaining challenges and suggestions on how to improve the fuel substitution ratio, establish processing center and develop life cycle model are put forward.