Simulation and Application of O₂–N₂ Mixing Top-blowing Method in MURC Steelmaking Process

Abstract

The O₂ and N₂ mixing top-blowing method could effectively improve the mixing degree and suppress the temperature increase rate of the molten bath in vanadium extraction converter. In this paper, four kinds of top-blowing lances designed by an extra N₂ flow rate and various Mach numbers have been investigated by a series of water experiments and numerical simulations. On the basis of result, the mixing time was first increased and then decreased with the increase of lance height, and the lance height of 1400 mm obtained the longest mixing time. There were two high-velocity regions generated by impaction of top-blowing jets and stirring of bottom-blowing bubbles. Simultaneously, there were two low-velocity regions formed by the block of furnace wall, and one low-velocity region formed by the local eddy. Comparing with the current top-blowing lance, all three new kinds of top-blowing lances obviously improved the kinetic condition and impaction cavity area of molten bath, which would further be improved with a larger design Mach number. Therefore, an appropriate top-blowing lance had been selected in the industrial application research, which achieved a shorter melting time and a faster vanadium extraction rate, in contrast to the current lance.