The use of gas quenching to granulate blast furnace slag enables the effective recovery and reuse of the residual heat contained within the slag. At the same time,it prevents the environmental damage caused by the accumulation of blast furnace slag,thus facilitating its high-value recycling. The height of the gas quenching nozzle is a key control parameter during the cooling and solidification process of the slag beads,which directly affects the quality of the granulated slag beads. To this end,the granulation process of slag during gas quenching is simulated,a granulation model is constructed, and the mechanism of slag fragmentation is analyzed. The landing time of the slag beads is calculated by the simulation model,and then the optimal nozzle height is determined to obtain the optimal granulation effect of the blast furnace slag. The results show that there are five morphological changes of “slag-liquid film-liquid filament-droplet-slag bead” in the crushing process of blast furnace slag,and the cooling and solidification process of the slag starts from the windward side,followed by the upper and lower sides and the leeward side. When the initial velocity of the gas is 420 m/ s,the diameter of the gas quenching injection hole is 0. 051 m,the processing volume of blast furnace slag is 60 t/ h,and the height of the meeting point between blast furnace slag and gas quenching wind is 0. 2 m,the flight speed of the slag beads can reach 9 ~12 m/ s. Under the premise of ensuring that the slag beads solidify and do not stick after landing,the nozzle height is set in the range of 2. 2 ~4. 5 m. At the appropriate nozzle height,the blast furnace slag blowing granulation mainly forms slag beads and ungranulated fibers. The particle size distribution of slag beads is mainly normally distributed, relatively uniform,and the particle size is mainly concentrated in 1 ~2. 5 mm. The beading rate basically shows a gradual increase trend with the increase of nozzle height,and the increasing trend slows down after more than 4 m. The conclusions can provide data support for the industrial application of dry gas quenched granulated blast furnace slag.