Abstract: In order to understand the phenomenon that solid inclusions are easier to be removed in contrast to liquid inclusions during steelmaking process, a mathematical model was established to describe the separation processes of octahedral and plate-like inclusions based on the analysis of the forces acting on inclusions at the steel-slag interface. Besides drag force, buoyancy force and capillary force as well as added-mass force considered in the previous mathematical models, the interfacial resistance force caused by the deformation of the steel-slag interface was further considered in the model of this study. Based on the model, the effects of interfacial tension between phases (steel, slag and inclusion) and slag viscosity on the separation process were studied. The results showed that the capillary force was the driving force for solid inclusion crossing the interface between steel and slag, and it was determined by the overall wettability of the system (steel, slag and inclusion) and the shape of an inclusion. Meanwhile, the drag force was the resistance force for the separation of an inclusion at the steel-slag interface, and the slag viscosity was an important factor to this force. Without the consideration of chemical dissolution, the released interfacial free energy of the steel-slag-solid inclusions system was a driving energy for the separation of solid inclusions at the interface, and it would be sufficient to make most solid inclusions separate from the interface. Furthermore, the Gibbs free energy released during the dissolution of inclusions was much larger than the interfacial free energy. According to the principle of minimum free energy, the dissolution process would promote the entering of solid inclusions into slag. Therefore, the Gibbs free energy was also a driving energy for the separation process. Considering the separation time was very short (less than 10-3 s), in steelmaking process, solid inclusions would be removed quickly at steel-slag interface, once they contact with the steel-slag interface.

Key words: separation process, mathematical model, solid inclusions, steel-slag interface, dissolution process

摘要： 为了解释炼钢过程中固态夹杂物比液态夹杂物更易去除的现象，基于分离过程中受力分析，建立了描述八面体和板状夹杂物穿过钢-渣界面行为的数学模型。与传统数学模型相比，本模型考虑了夹杂物周围钢-渣界面变形引起的界面变形阻力。同时，采用该模型研究了各相(钢液、渣和夹杂物)界面张力和顶渣黏度等因素对固态夹杂物穿过钢-渣界面分离行为的影响。结果表明，若忽略固态夹杂物溶解过程，钢液、顶渣和夹杂物体系释放的界面自由能是固态夹杂物穿过钢-渣界面的驱动能，且该动能已足够保证多数固态夹杂物穿过钢-渣界面进入渣层。固态夹杂物溶解过程释放的吉布斯自由能远大于该过程释放的界面自由能，固态夹杂物接触钢-渣界面的瞬间被顶渣吸收去除。

关键词: 分离过程, 数学模型, 固态夹杂物, 钢-渣界面, 溶解过程