基于洁净钢高效生产的新型电磁冶金技术研究

It is of important strategic significance to change the current situation of China's steel industry, whose main dilemma is the overcapacity of low-end steel products and lack of high-end steel products, especially the serious lack of high-end steel production technologies. For clean steel production with high efficiency, in this study, several new technologies of electromagnetic metallurgy are proposed for the continuous casting process from ladle to mould stage such as electromagnetic induction-controlled automated steel-teeming, electromagnetic prevention of vortex forming in ladle, electromagnetic swirling flow nozzle above mould. Fe-C alloy with a similar composition of molten steel is used to replace the conventional nozzle sand. Then the plugged zone of the alloy is melted by electromagnetic induction heating. This would obtain smooth automated steel teeming and improve the cleanliness of steel significantly. An electromagnetic force is used to offset the force which forms the vortex at the bottom of the ladle. Because of this, the vortex critical height would be reduced or the steel-teeming without vortex would be realized. The amount of slag would be reduced significantly, and the metal yield would be increased. A rotating electromagnetic force is induced to drive the molten steel in nozzle to rotate, so as to avoid nozzle clogging, uniform the nozzle outflow and improve the flow field in mould, then reduce the meniscus fluctuation and prevent slag entrapment. According to different problems, these new technologies could be used independently or combined, and the efficient production of clean steel will be realized. This study is beneficial to form new electromagnetic metallurgy technologies with independent intellectual property rights, enhance the competitiveness and the independent innovation ability of China's iron and steel enterprises.

改变我国钢铁工业低端钢材产能过剩、高端产品不足，尤其是高品质钢材生产技术严重缺乏的局面具有重要的战略意义。面向洁净钢高效生产，本研究针对连铸过程从钢包到结晶器的工艺环节提出了钢包电磁感应加热出钢技术、钢包底部电磁防漩技术和浸入式水口电磁旋流技术等多项电磁冶金新技术。利用和钢液成分相同或相近的铁碳合金替代传统引流砂，采用电磁感应加热的方法熔化合金封堵层，实现自动开浇并显著提高钢的洁净度。利用电磁力抵消钢包底部诱发漩涡形成的力，降低漩涡临界高度或实现无漩涡出钢，大量减少下渣量并提高金属收得率。对浸入式水口施加旋转电磁力，使水口内钢液旋转，避免水口堵塞并均匀水口出流，直接改善结晶器内流场，抑制弯月面波动，防止卷渣并减少钢坯夹杂物。针对不同问题，上述新技术可独立或组合使用，实现洁净钢的高效生产。该项目有利于形成具有独立知识产权的电磁冶金新技术，提高我国钢铁企业竞争力和自主创新能力。

改变我国高品质钢材自主生产技术严重缺乏的局面具有重要的战略意义。面向洁净钢高效生产，本项目针对连铸过程从钢包到结晶器的工艺环节，提出了钢包电磁感应加热出钢技术、浸入式水口电磁旋流技术和钢包底部电磁防漩技术等研究。电磁感应加热出钢技术中，利用和钢液成分相同或相近的铁碳合金替代传统引流砂，采用电磁感应加热的方法熔化合金封堵层，实现完全自动开浇并大幅提高钢的洁净度。建立了模拟电磁出钢系统的磁-热-结构耦合数值模型，搭建了实验室和工业生产试验装置。阐明了铁碳合金颗粒特性对固液界面位置与封堵层厚度的作用规律和作用机制，揭示了线圈和电源参数对电磁出钢效果的影响规律。通过模铸和连铸工业实验，解决了封堵层位置确定、电磁感应加热效率等关键问题，验证电磁出钢技术和工艺及装置的可行性，并成功进入成果转化阶段。浸入式水口电磁旋流技术中，通过施加旋转电磁力使浸入式水口内钢液旋转，直接解决水口偏流问题，改善结晶器内流场和温度场，提高铸坯质量。分别针对圆坯、方坯和板坯连铸，建立了模拟电磁旋流水口和结晶器内的磁场、流场、温度场多场耦合数学模型，阐明了电磁旋流对浸入式水口及结晶器内钢液流场、温度场的影响规律和影响机制。在液态金属实验验证的基础上，利用自主开发的电磁旋流设备和工艺，成功实施了方坯和大圆坯的工业实验，显著提高了铸坯的等轴晶比率，改善了宏观偏析。钢包底部电磁防漩技术中，提出利用电磁力等外力改变漩涡流场分布，降低漩涡临界高度。通过理论分析、数值模拟和水模型实验，揭示了钢包底部漩涡的生成机理和抑制漩涡生成的影响因素及其作用机制，提出了利用电磁力和吹气方式通过扰乱形成漩涡的流场进而抑制漩涡形成的技术原型。该项目形成了多项具有独立知识产权的电磁冶金新技术，可独立或组合使用，降低夹杂物引入而实现洁净钢高效生产，有利于提高我国钢铁企业竞争力和自主创新能力。