超低碳钢RH脱碳喷吹CO2多相流传输行为及渣-金-气反应特性基础研究

RH快速深脱碳及后续可浇性稳定控制一直是超低碳钢生产面临的主要问题。申请人前期研究表明，CO2可取代Ar作为超低碳钢RH脱碳侧吹气体，但脱碳后期气泡表面发生的增碳反应会在一定程度上降低脱碳速率，且CO2与超低碳Fe-C-O熔体作用机理尚不明确。为此，本项目针对超低碳钢RH侧顶复吹CO2强化脱碳问题，采用热力学分析、热态实验、数值模拟和生产实践相结合的方法，研究渣-金-气反应热力学和动力学，揭示CO2与Fe-C-O熔体作用脱碳、增碳和增氧机制以及渣金界面氧传质规律，建立CO2-CO-钢水-精炼渣多相流、溶质传输与渣-金-气反应耦合数学模型，探明喷吹CO2流体流动特征，获得钢水中[C]和[O]含量变化规律，为实现CO2资源化利用于超低碳钢RH快速深脱碳提供理论指导。在此基础上，探究将进站钢水[O]含量及顶渣氧化性控制在较低水平的CO2喷吹方法，为提高超低碳钢洁净度和可浇性探索新的思路和途径。

The rapid and deep decarburization of the Ruhrstahl-Heraeus (RH) degasser and the stability control of the subsequent castability are difficult problems to solve at present in the production of ultra-low carbon steel. The applicant's study shows that it is practicable to replace the Ar by CO2 as a side-blown gas during the RH decarburization process of ultra-low carbon steel. However, decarburization rate at the later stage of decarburization process is slightly weakened by the use of CO2 injection due to the occurrence of local carburization reaction. Besides, the reaction mechanism between the ultra-low carbon Fe-C-O melt and CO2 gas is still unclear. Based on the thermodynamic analysis, high temperature experiment, numerical simulation and practical production, the strengthening decarburization of ultra-low carbon steel is studied in the RH degasser with side and top combined injecting CO2. First, thermodynamics and kinetics among slag, melt and gas are researched to reveal the decarburization, carburization and oxygenation mechanisms between melt and gas as well as the oxygen mass-transfer law between melt and slag. Then, a reasonable mathematical model with regard to the CO2-CO-steel-slag multiphase flow, solute transport and slag-metal-gas reaction is constructed to clarify the flow characteristics as well as the change rule of dissolved [C] and [O] in the RH degasser. This research will provide theoretical guidance for the CO2 utilization as resource in RH rapid and deep decarburization of ultra-low carbon steel. Based on these, CO2 injecting method is deeply investigated to minimize the initial [O] content and slag oxidability, which will provide new ideas and ways to further improve the cleanliness and castability of ultra-low carbon steel production.