Abstract:

The steel industry is a major energy consumer and carbon emitter, so seeking zero-carbon raw materials that can replace traditional coal in the context of carbon neutrality is a key carbon emission reduction technology for the steel industry. Biochar has the characteristics of carbon neutrality, and the carbon content and calorific value are close to that of coal, which is an ideal alternative raw material for pulverized coal and coke. This paper introduced the potential utilization methods of biochar in coking, sintering and blast furnace ironmaking, focused on the physical and chemical characteristics of biochar when applied to blast furnace ironmaking and expounded the effects and mechanisms of biochar alkali metal, strength, particle size and specific surface area in coal substitution. Aiming at the problems of alkali metal reducing coke strength, demineralization methods such as pickling were introduced to reduce the content of biochar alkali metal. Aiming at the problem that biochar had poor mechanical strength and was difficult to enter the furnace, the formation mechanism of coke strength and the enhancement process of biochar molding were summarized. In view of the problem of poor fluidity of coking coal mixture caused by biochar, the negative impact on coke was reduced by adjusting the particle size and specific surface area of biochar. Finally, the domestic and international progress of biochar in replacing pulverized coal and coke for blast furnace ironmaking and the expected CO₂ emission reduction effect were summarized. By analyzing the challenges of the current industrial application of biochar instead of coal/coke and the related research on life cycle assessment, it will provide technical support for the future carbon neutrality of the steel industry.

Key words: biomass, biochar, blast furnace ironmaking, substitution for coal and coke, carbon dioxide, carbon neutral, life cycle assessment

摘要：

钢铁行业是能源消耗和碳排放大户，因此在碳中和背景下寻求可替代传统煤的零碳原料是钢铁行业重点发展的碳减排技术。生物炭具有碳中性特征，碳含量和热值与煤接近，是煤粉和焦炭理想的替代原料。本文系统介绍了生物炭在炼焦、烧结、高炉炼铁中的潜在利用途径，并进一步聚焦生物炭应用于高炉炼铁时所需具备的理化特性，阐述了生物炭碱金属、强度、粒度与比表面积在替煤代焦时的影响及机理。针对碱金属降低焦炭强度等问题，介绍了酸洗等脱矿方法降低生物炭碱金属含量；针对生物炭机械强度差难以入炉问题，总结了焦炭强度形成机理和生物炭成型增强工艺；针对生物炭导致炼焦煤混合物流动性变差问题，通过调控生物炭粒度和比表面积以降低对焦炭的负面影响。最后，总结了生物炭替代煤粉和焦炭高炉炼铁的国内外进展及预期CO₂减排效果。通过分析生物炭替煤代焦目前工业应用中存在的挑战以及生命周期评价的相关研究情况，为未来钢铁行业实现碳中和提供技术支撑。

关键词: 生物质, 生物炭, 高炉炼铁, 替煤代焦, 二氧化碳, 碳中和, 生命周期评价