让中间包干式料浇钢塌包难题迎刃而解 solution of the problem of ladle collapse in casting of steel.

在连铸生产过程中，中间包内的耐火材料直接与高温钢液接触，其质量直接影响着中间包的寿命以及钢液的质量。在中间包开浇初期，中间包冲击区四周的渣线容易出现坍塌问题，会导致生产中断、严重时导致钢水泄漏，引发安全事故，威胁操作人员的生命安全。为了减少这些影响，北京联合荣大科技工作者采取了下列有效的预防和应对措施，避免材料的浪费，确保连铸生产的连续性和安全性。

In continuous casting, the refractory material in the tundish comes into direct contact with the high-temperature molten steel, and its quality directly affects the lifespan of the tundish and the quality of the molten steel. In the initial stages of casting, the slag line around the impact zone of the tundish is prone to collapse, which can lead to production interruptions, and in severe cases, molten steel leakage, causing safety accidents and threatening the lives of operators. To mitigate these impacts, Beijing United Rongda Technology has implemented the following effective preventative and responsive measures to avoid material waste and ensure the continuity and safety of continuous casting production.

中间包干式料塌包的原因主要包括施工问题、材料设计问题等。具体原因及应对措施如下：The main reasons for the collapse of dry-fill tundishes include construction problems and material design issues. Specific causes and corresponding solutions are as follows:

一是施工问题。

 首先，振捣不密实会导致干式料内部存在较多的孔隙和微裂纹，这些缺陷会降低材料的整体强度，导致开浇初期出现塌包风险。为确保施工过程中振捣密实，振动前应检查振动电机振动力度和频率，控制振动时间，必要时采用人工使用专业工具辅助振捣，振动时取掉胎模定位工具以免影响振动效果。

 其次，钢水液面附近的区域是中间包中最容易受到侵蚀的部分，如果布料过程中渣线料和包壁料过渡部位偏上靠近钢水液面位置，可能会因为频繁的温度变化而遭受热冲击，导致该薄弱部位耐火材料出现裂纹或剥落。 包壁料施工后应检查布料高度，确保渣线料和包壁料过渡部位避开钢水液面位置，同时浇钢过程中应避免低液面浇钢。

 第三，干式料带模烘烤后冷却时间过短，干式料与胎模之间间隙过小，脱模时会导致干式料粘模，严重时将导致出现大面积横向裂纹。 脱模前应确保干式料与胎模之间有足够的间隙，避免拔模困难，同时可以在胎模表面均匀涂抹脱模剂提高胎模的润滑效果。脱模过程中应平起平落减少意外的磕碰产生的局部裂纹。

First, there are construction issues.

• Firstly, insufficient compaction during vibration will result in numerous pores and microcracks within the dry refractory material. These defects reduce the overall strength of the material, leading to a risk of ladle collapse during the initial pouring stage.To ensure thorough compaction during construction, the vibration motor's intensity and frequency should be checked before vibration, and the vibration time should be controlled. If necessary, manual vibration using specialized tools should be employed. The positioning tools for the formwork should be removed during vibration to avoid affecting the vibration effect.

• Secondly, the area near the molten steel surface is the most vulnerable to corrosion in the tundish. If the transition between the slag line material and the ladle wall material is too high and close to the molten steel surface during the placement process, frequent temperature changes may cause thermal shock, leading to cracks or spalling of the refractory material in this weak area.After the ladle wall material is installed, the placement height should be checked to ensure that the transition between the slag line material and the ladle wall material avoids the molten steel surface. Furthermore, pouring steel at a low molten steel level should be avoided during the pouring process.

• Third, if the cooling time after baking the dry material in the mold is too short, and the gap between the dry material and the mold is too small, the dry material will stick to the mold during demolding, which can lead to large-area transverse cracks in severe cases.

Before demolding, ensure there is sufficient gap between the dry material and the mold to avoid difficulty in demolding. At the same time, apply a release agent evenly to the surface of the mold to improve its lubrication. During demolding, lift and drop the material smoothly to reduce localized cracks caused by accidental impacts.

二是材料设计问题。

　　首先，如果渣线料和包壁料的高温线性变化差异较大，那么在高温使用过程中，这两种材料之间的热膨胀不匹配可能导致结合部位出现裂缝或分层，从而损害其完整性。

　　在进行材料设计时应考虑渣线料和包壁料热膨胀系数相近，以减少高温下的线性变化差异导致的分层。

　　其次，中间包耐材会加热至1000℃以上才能投入使用。干式料工作层烘烤过程中树脂在200～800℃时会分解，干式料在1000℃时镁砂无法烧结，因此结合强度较低，易发生塌落与剥落现象。

　　在大火烘烤时间较长的情况下，引入中温烧结机提高干式料中温强度，避免开浇初期钢水冲击导致的剥落坍塌.

Second, there are material design issues.

• Firstly, if the thermal expansion coefficients of the slag line refractories and the cladding wall refractories differ significantly at high temperatures, the mismatch in thermal expansion between these two materials during high-temperature use may lead to cracks or delamination at the bond joints, thus compromising their integrity.Therefore, material design should consider that the thermal expansion coefficients of the slag line refractories and the cladding wall refractories are similar to minimize delamination caused by differences in thermal expansion at high temperatures.

• Secondly, the tundish refractory material is heated to over 1000℃ before use. During the baking process of the dry refractories working layer, the resin decomposes at 200–800℃, and the magnesia cannot sinter at 1000℃, resulting in low bond strength and a tendency for collapse and spalling.In cases where the high-temperature baking time is prolonged, introducing a medium-temperature sintering machine can improve the medium-temperature strength of the dry refractories, preventing spalling and collapse caused by the initial impact of molten steel during casting.