渣金弥散体系相际传质与界面结构演变协同强化机理研究

In slag-metal emulsion system of metallurgical process, the transfer of components between the two phases usually results in interfacial tension gradient, which induces the change of droplet surface structure and thus influences the mass and heat transfer as well as the chemical reaction. However, the mechanism of synergy between the inter-phase masstransfer and the droplet surface structure change is still unknown. As a result, the macroscopical rules of reactor cannot be grasped exactly, which influences the accurate judgment and the “narrow window” control to the refining process. Therefore, in this project the evolution of metal droplet interface induced by oxygen transfer in converter emulsion slag is studied. The evolution law of interface tension is determined by the study on the change of interfacial tension during oxygen transfer between slag and metal. The composition and morphology of the metal droplet during the component transfer process are studied, and the quantitative relationships of the key dynamic parameters and the interface area with the change of interfacial tension are constructed. Then the reaction rate model for the deformed droplet is established. The critical condition for droplet breakage is explored, and the number, size and morphology of the fragmentized droplet are clarified, by which the mechanism of droplet fragmentation is finally clarified. Combining the developed reaction rate model of the child droplets, a comprehensive macro-dynamic model of the process is established to characterize the reaction rate of the fragmentation and evolution process of the droplet. The project will have methodological and practical value in completing metallurgical macro kinetics and its application. The results can supply scientific teaching for thoroughly understanding the slag-metal reaction mechanism in the emulsion slag and refining process laws.

冶金渣金弥散体系精炼反应过程溶质组元相间迁移产生渣金界面张力梯度，诱发液滴界面结构演变，影响相间质能传递和化学反应过程。然而目前关于渣金相际传质与界面结构演变的协同作用机理尚不明确，导致难以准确把握反应器宏观规律，进而影响对冶炼进程的准确判断和“窄窗口”控制。为此，本项目以转炉乳化渣内氧传递诱发金属液滴界面演变为对象，通过研究氧迁移过程渣金界面张力变化，明确界面张力的演变规律；研究传质过程金属液滴成分和形貌，构建过程关键动力学参数和界面积与界面张力变化的定量关系，建立描述变形液滴的反应速率模型；探明液滴发生破碎的临界条件，明确破碎后子液滴数量、尺寸和形貌，掌握液滴破碎机制，并联合子液滴反应速率模型，建立过程综合宏观动力学模型，表征液滴破碎演变过程的反应速率。项目在完善冶金宏观动力学及其应用方面具有方法上的意义和应用价值，研究结果可为透彻解析乳化渣内渣金反应机理和冶炼过程规律提供科学指导。

现代冶金过程常常构造渣金多相弥散分布体系，体系内质能传递过程在很大程度上决定了反应器过程的速率和效率。然而目前对于渣金弥散体系内质能传递机理掌握不明，导致难以准确把握反应器宏观规律，进而影响对冶炼进程的准确判断和“窄窗口”控制。项目以转炉炼钢过程渣金弥散体系内金属液滴-熔渣相间非稳态传质为研究对象，从单个金属液滴-熔渣界面物理化学的微观尺度出发，研究溶质组元跨金属液滴-熔渣界面非稳态迁移过程及其诱发的界面结构变化，以及二者的协同作用规律，进而解明液滴-熔渣相间的质能传递机理。取得的具体成果是：基于CLSVOF界面追踪方法，构建了渣金弥散体系内溶质（氧）组元在铁液滴-熔渣相间非稳态传质耦合界面结构演变的数值模型，对相界面传质的微观尺度和非稳态过程进行了可视化跟踪和表征；通过对界面传质过程速率、界面张力、界面Marangoni对流形成和发展及强度、界面形状及结构等关键界面参数和现象演变的定量表征，揭示了溶质组元穿越铁液滴-熔渣相界面传质与其引起的Marangoni效应的协同作用规律；阐明了液滴尺寸、溶质组分浓和熔渣物性等参数对Marangoni效应及传质过程的影响规律；研究结果丰富了冶金界面科学和反应工程学知识体系，深化了对渣金弥散体系及反应器内质能传递机理的理解；基于项目研究成果，发表学术论文8篇，其中SCI论文5篇，授权发明专利2项，参加国内外学术会议3人次，培养硕士研究生2名。