Abstract: Nowadays, more and more scrap is required to be added in the bath of the converter accompanied by the increasing requirements on the environment and increasing volume of available scrap in China. Consequently, the melting rate of the scrap would be significant if a large amount of scrap is added into the bath for the steelmaking process. The carbon content, temperature, and flow of the bath are the main factors that influence the scrap melting process in a bath of hot metal. The current study mainly focused on the effects of bath flow on the melting behavior based on a scrap melting process performed in the experiment in which the scrap melting behavior in a bath was investigated. Specifically, the effects of nature convection and driven convection on the meting process were investigated by applying a mathematical model. The results found that nature convection was formed in the vicinity of the melting interface when a scrap bar was immersed in the melting bath of hot metal. As a result, the heat transfer between bath and scrap can be enhanced by the flow at the melting interface. Also, the hot metal with high carbon content was driven to the melting interface. In turn, the melting rate was accelerated. The intensity of nature convection decreased when the initial temperature of the scrap was increased. The melting rate was remarkably increased when the driven convection was introduced to the bath. Compared to the initial temperature of 25℃ with a melting rate of 107 mm3/s, the melting rate was only 50 mm3/s when the initial temperature of scrap was 1000℃ at 5 s. In addition, when the melting was performed at 15 s, the rest volume of the scrap with the nature convection was 1054 mm3, which was 2.3 times for driven convection with the driven flow velocity of 0.15 m/s. Also, the melting rate of the scrap with the driven flow velocity of 0.15 m/s was about 1.8 times that of the nature convection at 10 s.

Key words: Scrap, melting, bath, convection, converter, carburization

摘要： 随着我国环保要求日益严格和废钢量的增加，转炉炼钢过程中对废钢的使用量将逐渐增加。因此，大量废钢加入转炉后废钢的熔化将是一个非常重要的问题。熔池中碳含量、熔池温度和熔池流动是影响废钢熔化的重要因素。本工作以废钢在铁水熔池中的熔化实验过程为研究原型，利用数值模拟方法对废钢熔化过程中熔池流动对废钢熔化的影响进行研究，主要考察了熔池自然对流和强制对流对废钢熔化过程的影响规律。结果表明，废钢浸入熔池后，熔池和废钢间的温差使界面附近区域产生自然对流，界面处的流动可以加速熔池和废钢间的传热，并驱动高碳铁水向熔化界面运动，加速熔化过程。废钢初始温度升高，熔池中产生的自然对流强度下降。当熔池中流动为强制对流时，废钢熔化速率大大提高。熔化进行到5 s时，初始温度为25℃时的废钢棒熔化速率为107 mm3/s，而初始温度为1000℃时的废钢棒熔化速率仅为50 mm3/s，不到前者的50%。在15 s时刻，自然对流作用下废钢熔化剩余量为1054 mm3，是驱动速度0.15 m/s下的2.3倍；在10 s时，强制对流驱动速度0.15 m/s时废钢的熔化速率约为自然对流下的1.8倍。

关键词: 废钢, 熔化, 熔池, 对流, 转炉, 渗碳