Abstract: Gas quenching dry slag granulation process is one of the dry slag treatment processes,and granulation performance mainly includes the average diameter,size distributions and bead forming rate.The effects of different gas velocity and slag viscosity on the granulation properties were experimentally studied.The results indicates that the particle size is mainly distributed between 1～3 mm.With the increase of airflow velocity,average diameter of slag particles decreases,and the proportion of the particles which are smaller than 3 mm increases gradually.Bead formation rate firstly increases and then decreases.With the increase of viscosity,average diameter of slag particles increases,and the proportion of the particles smaller than 3 mm decreases gradually,and bead formation rate decreases.The optimum airflow velocity is 550 m/s and low viscosity is beneficial to improve the granulation performance.With the increase of airflow velocity,the unsteady wave is strengthened and the ligaments are thinner,which is readily to break,so the average diameter of droplets is reduced.But the heat transfer effect is enhanced,which leads to the formation of fibers,so the bead formation increases firstly and then decreases.With the increase of viscosity,the unstable wave decreases,the diameter of the droplet increases,and the bead forming rate decreases.