长水口对连铸中间包钢液保护浇注作用的研究进展

全球钢铁产品很大比例上是通过连铸工艺生产的，而中间包保护浇注是连铸生产高品质洁净钢的关键环节之一。长水口是连接于钢包和中间包之间的耐材质通道，长水口的发明和使用在连铸技术发展过程中起到了重要的作用，并与中间包的保护浇注效果有着紧密的联系，具体包括防止稳态和非稳态浇注过程中的二次氧化和来源于空气/渣/耐材/引流砂等的污染。本文基于中间包钢液污染的来源和形式，引申出了长水口在这些方面可以起到的潜在作用，并回顾了长水口在连铸发展早期的发明、工业实验效果和不断优化的历程。工业实践证实了长水口优良的保护浇注功能，但其实际效果与长水口的结构和操作工艺紧密相关。因此，分析了不同的长水口结构（包括工业化的长水口和一些新的设计理念）对保护浇注的影响，重点评述了喇叭型长水口在改善钢液洁净度和提高生产效率方面的优势。讨论了长水口的浸入深度和偏斜等操作工艺参数与保护浇注之间的关系。结合新时期炼钢?连铸的发展形势，指出了未来长水口结构功能一体化的发展方向，具体表现在长寿化、轻量化、多功能化和绿色化等方面。 

Research progress on the role of ladle shroud in protecting molten steel during teeming in continuous-casting tundishes

The global steel yield heavily relies on the continuous-casting process in the modern steel industry. Thus, the implementation of protected teeming in continuous-casting tundish for high-quality clean steel production is essential. Ladle shroud is a refractory device that contains the teeming stream between ladle and tundish. The invention and application of the ladle shroud play a significant role in the development of continuous-casting technology and considerably influence the performance of protected teeming, including protecting molten steel from reoxidation and contamination from air/slag/refractory/ladle filler sand during both steady-state and transient casting periods (i.e., first-heat filling, ladle change, and tundish emptying). In this review, the sources and forms of atmospheric contamination of molten steel in the tundish were addressed and the possible solutions to the problems encountered during the use of the ladle shroud were proposed by considering the invention, industrial trials, and progressive optimization in the early stage of the development of continuous casting. The ladle shroud has been proven to effectively protect the teeming stream, which, however, is closely associated with the structural design and operating practice. Thus, the effect of the structural design of the ladle shroud, including two types of industrialized ladle shroud and several new designs, on protected teeming was analyzed and the advantage of the trumpet-shaped ladle shroud over the conventional ladle shroud in terms of production efficiency and molten steel cleanness was emphasized. The materials of the ladle shroud have also been progressively enhanced to prolong its service life and achieve a stable service performance. The influence of operational parameters, including the immersion depth of the ladle shroud in tundish and misalignment, was also discussed. On the basis of current research and development work in the steelmaking continuous-casting field, the future development direction of the ladle shroud was identified to be structure–function integration, characterized by long service life, lightweight, multifunction, and eco-friendly manufacturing.