Generally, as a thumb rule, between 0.10 kg to 0.24 kg per ton of liquid steel. However, it depends also on the extent of sequence casts and ladle and tundish configurations. General experience from many steel plants show that RHAN consumption is nearly 50% lower than conventional covering compounds like rice husk ash powder.

No. Due to its self-spreading characteristics, RHAN can be added near the turbulent zone (liquid steel entry zone) and it will spread by itself within a few seconds. However, in case a baffle (dams and weirs) is used in the tundish, obviously RHAN needs to be added on both sides of the baffle. Moreover, in case any other additive like synthetic slag, etc are added in the tundish, then for effective results RHAN should be added in 3 or 4 segments of the tundish, viz, stopper area, shroud area, thermal probe area, etc.

Generally, argon flushing in the tundish to prevent air ingress is fairly soft (less than 0.8 bar pressure), so this does not create any significant turbulence or directional metal flow. But in case of excessive argon bubbling there will be turbulent metal flow away from the ladle shroud. This will tend to push the RHAN away from the shroud area due to its free-flowing nature, thus exposing the tundish metal to “red eye” phenomena.