Modelling the processes of nonmetallic inclusions removal in the tundish of the slab CCM

The analysis of the main approaches to the description of the processes of nonmetallic inclusions removal in the tundish during continuous casting is performed. It is shown that in studying the hydrodynamic processes in the tundish, the distribution curves of residence time (RTD) are widely used, which are described by a combination of idealized cells. A combined mathematical model for the removal of nonmetallic inclusions in the tundish of slab CCM due to flotation and floating is formulated. The possibilities of their removal for limiting variants of mixing condi-tions, ideal mixing and ideal plug cells, as well as the possibility of removal of nonmetallic inclusions with intermediate variants of stirring intensity, in the presence of circulation flows, are analyzed. It is shown that the comparatively higher proportion of large non-metallic inclusions remains at the outlet of the ideal mixing cell than in the outlet of the ideal plug cell, the increase in the fraction of the ladle volume with the ideal plug regime (with laminar flow) leads to a decrease in the residual fraction of nonmetallic inclusions. It has been determined by calculation that when blowing with argon in the casting section of the tundish of a two-strand continuous casting machine, the flotation efficiency depends on the size of the nonmetallic inclusions (small inclusions are practically not removed) and the size of the gas bubbles (small gas bubbles and a decrease in their dispersion in size provide a higher rate of removal of nonmetallic inclusions), as well as the average residence time of the metal in the bubbling zone. It has been calculated that the flotation of nonmetallic inclusions significantly increases the rate of removal of small particles with a diameter of 20-40 μm, which are practically not removed in the tundish without blowing, only with flow control devices. The results of the calculation are confirmed by the results of industrial experiments