Ca-Fe基高反应性焦炭在富氢高炉内的溶损行为

Improving coke reactivity and hydrogen reduction are two kinds of new ironmaking technology to reduce emissions of CO2 from different angles. The coupling between two kinds of technology can not only reduce the emission of CO2 but also improve the reaction efficiency in a blast furnace, which is an important developing way of green production of iron and steel. In this project, the high-strength and high-reactivity cokes are prepared by addition of CaCO3 and Fe2O3 as the Ca and Fe model compounds. By analyzing the reaction environment in the hydrogen-rich blast furnace, we study the solution loss reactions of cokes in different temperatures (900-1300℃) and atmospheres (H2O/CO2) to understand the difference in the solution loss behaviors between the high-reactivity coke and the traditional coke. The deterioration mechanism of Ca/Fe based high reactivity cokes in the atmosphere of CO2 and H2O is clarified on that basis. Also, quantum chemistry calculations on the solution loss reaction of cokes are studied to reveal the synergies and differences between the catalytic activity of Ca and Fe compounds. The research results will provide the experimental data and theoretical basis on the scientific evaluation of the high-strength and high-reactivity coke. And it will provide a new way for comprehensive utilization of the Ca and Fe industrial waste, such as steel slag. Ultimately, we hope to promote the application of the new ironmaking technology by high-reactivity cokes and the new ironmaking process by hydrogen reduction. And it is of important significance for the cleaner production and sustainable development of the iron and steel industry.

提高焦炭反应性和氢还原是从不同角度减少CO2排放的炼铁新型技术，两种技术的耦合既能大幅减少CO2排放，又能提升高炉的炉身效率，是实现绿色生态化钢铁生产的重要发展方向。本项目拟以CaCO3和Fe2O3配煤制备高强度、高反应性焦炭，从焦炭在富氢高炉的溶损反应环境入手，研究不同温度（900-1300℃）和气氛（H2O/CO2）下高反应性焦炭的溶损过程，认识Ca/Fe基高反应性焦炭与普通焦炭的溶损行为的差异性，阐明Ca/Fe基高反应性焦炭在含水气氛下的溶损劣化机理，结合量化计算揭示Ca、Fe化合物对焦炭溶损反应催化活性的差异性和协同性。本项目的研究结果既能为高反应性焦炭综合热性能的新型评价体系的建立提供实验基础和理论依据，又可为钢渣等富含Ca、Fe的工业废物的综合利用提供新途径，从而推动“高反应性焦炭炼铁新技术”和“氢还原炼铁新工艺”的生产使用，对实现钢铁行业的清洁生产和可持续发展具有重要意义。

“高反应性焦炭”和“富氢燃料喷吹”两种低碳冶炼新技术是我国长流程钢铁工业实现双碳目标的重要抓手，认识高反应性焦炭在富氢高炉的溶损行为对于高反应性焦炭的运用和高炉工序的绿色发展具有重要意义。本项目研发了一套连续进水、实时尾气分析的全自动焦炭反应性测定装置，阐明了Ca/Fe基高反应性焦炭在含水气氛下的溶损反应特性，发现了H2O和CO2与焦炭反应的竞争作用，并提出基于反应速率常数差值的抑制因子α定量表征碳溶反应和水煤气反应互相影响程度，Ca/Fe添加剂能够减小CO2对C+H2O反应的抑制程度，提高H2O与焦炭活性点反应的竞争力；根据CO2和H2O与焦炭溶损反应的动力学分析发现活化能顺序为Ca/Fe基焦炭<Ca基焦炭<Fe基焦炭<基础焦炭，明确了Ca/Fe添加剂对焦炭溶损反应的催化作用具有差异性和协同性；采用图像分析法和N2吸附法阐明了Ca/Fe基高反应性焦炭在含水气氛下的溶损劣化机理，基于微米孔结构演化提出溶损角度θ定量表征焦炭与CO2和H2O进行溶损反应的缩核程度，Ca/Fe添加剂能够减小焦炭溶损反应的θ角度、促进缩核程度，纳米孔和光学组织分析表明Ca/Fe添加剂促进焦炭溶损反应过程中表面介孔生成和增加OTI指数；采用XRD和SEM-EDS表征分析确定了Ca/Fe基高反应性焦炭的活性位点为铁酸钙和硅铝酸钙等化合物，阐明了Ca、Fe化合物对焦炭溶损反应的催化机理；结合反应力场和密度泛函理论计算揭示了CO2和H2O与焦炭气化反应的竞争机制，发现OH自由基是CO2和H2O与焦炭竞争反应的关键基元。项目培养硕士研究生6名，发表论文9篇，申请发明专利1项，获得河北省科学技术进步二等奖1项。