The Influence of Placement and Sintering Time of the Steel Ladle Filler-sand

Sammanfattning: The filler-sand is a barrier between the slide gate system and the liquid metal in the steel ladle. During the casting process, the sintered sand should brake due to the ferrostatic pressure from the molten metal to initiate the teaming. This procedure is called a spontaneous opening in the casting context. However, this is not always the case, as the filler-sand that protects the sliding gate, through which the metal passes, often blocks the exit hole. This study, taking place at Uddeholm in Hagfors, Sweden, investigates the preheating, the refining and the casting process by analyzing the ladle cleaning, sand additions, amount of sand, sintering times and stirring. The aim of the study is to contribute to a better understanding concerning the reasons for complications with the spontaneous opening of the tapping hole. The study finds that the pre-sintering time has a bearing on whether the free opening is successful or not, as the longest and shortest pre-sintering times proved to have a higher rate of non-spontaneous openings. The time from when stirring is stopped to when the sliding gate is opened also correlates well, where longer times lead to more non-spontaneous openings. However, there is no evidence of any correlation between how thoroughly the filler-sand covers the hole and the occurrence of non-spontaneous openings.