Abstract: An ironbath reactor with thick slag layer for smelting reduction was designed， and the influences of blowing parameters on bath mixing time were studied with a water model. The results showed that using singlenozzle bottom blowing， the influences of middle lance inclination angle and immersion depth and lower lance inclination angle are smaller and the influence of lower lance immersion depth is greater， compared with side blowing only. The mixing time with twonozzle bottom blowing is shorter than that with fournozzle bottom blowing. With the same number of bottom nozzles， the mixing time with asymmetric nozzle layout is shorter than that with symmetric layout. Comparing the mixing time of the six optimum blowing combinations， the asymmetrical twonozzle bottom blowing is the best combination for the reactor， and the corresponding optimum side blowing is as follows: 50° inclination angle， 180mm immersion depth of middle lance and 50° inclination angle， 180mm immersion depth of lower lance.

Key words: smelting reduction, ironbath reactor, thick slag layer, physical simulation, mixing time