Physical Simulations of Macromixing Conditions in One-Strand Tundish during Unsteady Period of Continuous Slab Casting Sequence

The tundish as a flow reactor has a special feature, that is, the liquid metal stays in its working capacity for a certain period of time before it enters the mold. This time is effectively used to correct the chemical composition of cast steel. The object of investigation is the wedge-type tundish, being a component of the continuous casting slab machine. According to the criterion of similarity, the glass model of the tundish is built to a 0.4 linear scale. A tracer is fed into water using the pulse-step method. During the casting sequences, the time for starting the alloying process, the depth of immersion of the ladle shroud, and the location of feeding the alloy addition change. On the basis of the recorded tracer concentration curves, the mixing time is calculated between the start of feeding the marker to the water and obtaining the required level of chemical homogenization in the water flowing out of the tundish model. Based on the conducted experiments, it is stated that mixing time depends on feeding positions, time of feeding initialization, and hydrodynamic conditions in the tundish during particular stages of the casting sequence.