Abstract: In the hydraulic model experiments of bottom argon blowing refining process, the traditional mixing criterion was determining the mixing degree by monitoring the tracer concentration with the help of one or two conductivity electrodes which were set in the ladle model. Due to the difference between the local mixing time at different positions and the randomness in the choice of monitoring positions, the measured mixing time may not be realistic. In regard to this, the fluid flow and mixing process were simulated by numerical calculation. The result showed that with the increase of mixing degree, the standard deviation of tracer concentration decreased. When the standard deviation was lower than 0.02, the mixing degree was 100%. Based on this, it was raised that 9 conductivity electrodes should be set at three sections which were distributed alone the height. When the standard deviation of tracer concentration was lower than 0.02, the concentration could be believed to be uniform. The effect of adding position on mixing time was also studied in this paper. The result showed that the mixing time was about 77.5s when the tracer was added from the position which was located at a distance about 1/6 radius from the center. When the tracer was added from the edge which was close to the plume, the mixing time was about 137.3s. The former position was the ideal alloy adding position.

Key words: bottom argon blowing, fluid flow, mixing time, adding position, numerical simulation