Physical Simulation Of Inclusion Removal From Liquid Steel In Swirling Tundish

Swirling flow tundish (SFT) is a kind of newly developed tundish. With a swirling chamber in the tundish, the function of turbulence inhibiting pouring pad can be fully realized, and at the same time, similar metallurgical effect with centrifugal flow tundish can also be attained without electromagnetic equipment of centrifugal flow tundish. It improves the tundish flow field and promotes inclusion floatation, coalescence and removal.In this paper, on the basis of the feasibility study of swirling flow tundish, polypropylene plastic particles are used to simulate the non-metallic inclusion. The floatation rate of non-metallic inclusion in steel was simulated. The flotation rate variation of inclusions with swirling chamber diameter, height, inlet flow rate, poison, particle sizes and quantity are studied. The unsymmetrical flotation rate in the two strand swirling flow tundish is studied because of the asymmetrical position of inlet. These results are essential for optimizing the position and parameters of swirling chamber in swirling flow tundish. Besides, the mixture of vacuum pump oil and liquid paraffin is employed to simulate the liquid slag in the tundish. The slag entrapment and slag layer opening by vortex and level fluctuation are studied. By physical simulation, the following conclusions are obtained:(1) Under certain diameter of swirling chamber, inclusion flotation rate approximately enhanced initially and the decreased under certain height of swirling chamber, the variation of inclusion flotation rate with swirling chamber diameter depends on the chamber height.(2) With the same swirling chamber, the inclusion flotation rate is not changed while rotating swirling chamber to vary the inlet direction. With increasing the flow rate of inlet, inclusion flotation rate is reduced differently.(3) Swirling flow tundish has advantage in inclusion floating rate, The optimal technological condition of single strand swirling flow tundish is:280mm in diameter and 140mm in height, compared with no swirling chamber, the removal of 73-977μm,55-73μm and 44-55μm inclusions increased form 85.16%,75.31%,61.87% to 87.14%,82.23%, 67.22% respectively.(4) Without swirling chamber, the steel flow in a two strand tundish is symmetrical, the distribution of floatation rate is symmetrical. The unsymmetrical inclusion flotation rate is induced by the asymmetrical position of inlet in swirling flow tundish. It is a good measure to improve the unsymmetrical distribution of floatation rate by rotating swirling chamber inlet direction 60°.(5) As the height of swirling chamber increased, the slag entrapment get severer; By contrast, as the diameter of swirling chamber increased, the slag entrapment is improved step by step.(6) As the height of swirling chamber increased, the slag layer opening get severer; By contrast, as the diameter of swirling chamber increased, the slag layer opening improved greatly.(7) As the thickness of slag layer increases, the slag entrapment gets severer, but the slag layer opening is improved. As the flow rate increased, both the slag entrapment and slag layer opening get more severer.