高反应性-高强度焦炭的制备基础及其在高炉过程的演变行为

In the blast furnace (BF) ironmaking process, the improvement of reaction efficiency in BF stack (namely the utilization of CO in the reducing process of iron ore) is very significant, which has the potential to allow a decrease in reducing agent rate and CO2 emission. According to the research at home and abroad in recent years, the use of highly reactive coke could help to improve the reaction efficiency by decreasing the temperature of the thermal reserve zone of BF. However, it is still indistinct so far that some fundamental aspects of the preparation for highly reactive coke and its reaction behaviours and strength degradation mechanisms in BF. Therefore, in this project, the co-carbonization mechanism will be researched between metallic minerals and coal in coking process, by which the formation and transformation of the microtexture, pore characteristic and microcrystalline structure, as well as the mineralogy transformation and occurrence of the metallic minerals could be analyzed. At the same time, the gasification of highly reactive coke with CO2 is also studied, by which the relationship between carbon matrix and mechanical strength could be found. Base on the analysis above, the quantitative characterization among metallic minerals and carbon matrix as well as metallurgical properties could be established, all of which will contribute to grasp the basic theory and key technology about the preparation of coke with high reactivity and high strength. In addition, the effect of high temperature treatment and alkali metel on gasification reaction behavior and strength will also be studied, and the relationship between carbon microstructure and strength is analyzed. On the basis of the above researches, the degradation mechanics of the highly reactive coke could be explored, which contribute to deepen understanding between reaction behaviors and degradation mechanics of coke in BF. The achieved research results above will provide some theretical basis and technical supports for application of high reactivity coke in the BF ironmaking.

提高高炉炉身工作效率对降低焦比，减少CO2排放意义重大。国内外最新研究表明，使用高反应性焦炭能够提升高炉反应效率。然而，高反应性焦炭的制备基础及其在高炉过程的演变行为尚未明晰。本项目拟通过研究金属矿物质与煤的共碳化行为，分析共碳化过程中碳的显微组织、孔结构、微晶结构的形成及演变规律，金属矿物质赋存状态的转变规律并阐释金属元素的迁移规律及分布特征；研究高反应性焦炭的气化反应行为及力学性能，分析焦炭发生气化反应的反应率分布、显微组织、孔结构、微晶结构与强度的关系，实现金属矿物质-微观结构-冶金性能的定量表征，掌握高反应性-高强度焦炭的制备基础。研究高温热处理及碱金属凝聚条件下高反应性焦炭的显微组织、孔结构、微晶结构、金属矿物质物相的变化规律及其对宏观性能的影响，探索高反应性焦炭的强度下降机理，深化对高炉内焦炭演变行为的认识。研究成果可为高炉使用高反应性焦炭提供理论基础及技术支持。

提高高炉炉身工作效率对降低焦比，减少CO2排放意义重大。研究表明，使用高反应性焦炭能够提升高炉反应效率。然而，高反应性焦炭的制备基础及其在高炉过程的演变行为尚未明晰。本项目针对煤与金属矿物质的共碳化行为、焦炭反应性和强度的影响机理及调控机制及高炉条件下高反应性焦炭的微观结构与宏观性能的演变规律等一系列问题开展了研究。首先，采用热重-差热技术研究了金属矿物质与煤共碳化过程，并进行动力学参数求解；通过X-射线衍射技术及矿物质物相定量方法分析共碳化过程中碳微晶结构及矿物相转变规律，为高反应性焦炭的制备提供了理论依据。其次，将不同种类含铁矿物质、不同含量催化性金属矿物质与煤共碳化制备焦炭，研究含金属矿物质焦炭气化反应行为及力学性能，分析不同条件下焦炭气化反应过程中矿物相转变特征，并分别采用第一性原理及结构分析方法阐释了金属矿物质催化气化反应机理；分别从煤碳化过程热塑性及胶质体新相结构转变和焦炭中矿物质、碳结构和官能团结构阐述了金属矿物质对焦炭强度的影响机理，同时，构建了焦炭反应性、强度、活性碳位与矿物质、微观结构之间的关系，实现了金属矿物质-微观结构-冶金性能之间的定量化表征，基于此，分析沥青及复合添加剂对焦炭强度的影响行为，优化金属矿物质与复合添加剂的添加量，制备出反应性为40.21 %、反应后强度为55.16 %的高反应性-高强度焦炭。最后，模拟高炉条件，阐释热处理温度及碱金属对高反应性焦炭结构、反应性及强度的影响特征，明确了焦炭气化反应在低碱金属存在下主要受一级反应控制，高碱金属存在下主要受二级反应控制，深化了高炉条件下高反应性焦炭的强度下降机理，为高反应性焦炭在高炉的运用提供理论支持。项目共计发表学术论文15篇，其中SCI检索5篇，EI检索4篇，获权发明专利3项，申请者获得了四川省金属学会冶金青年科技奖，获得四川省金属学会青年学术年会优秀论文一等奖。培养研究生6名，完成了项目计划的研究内容，达到了预期目标。