A novel atomization process based on a rotary cup atomizer (RCA) was proposed to manufacture iron powders using semisteel as the raw material. To achieve rapid cooling of iron droplets and efficient separation of iron powders from cooling water, a circle of water curtain was set around the RCA in the experimental setup. The effects of rotating speed, cup diameter, slope angle, and cup depth on the particle size of iron granules were investigated to meet the size requirement of iron powders applied as reductive agent during the sulfate process. Results indicated that the optimal conditions for the atomization of semisteel were a rotating speed of 1800 rpm, a cup diameter of 150 mm. Under such conditions, the accumulative fraction of the obtained iron granules that measured less than 0.45 mm reached a maximum of 93.12 wt% when the slope angle and cup depth were 45 degrees and 50 mm. Thus, this novel preparation process for iron powders with semisteel using RCA basically achieved the required particle size. The median diameter of the obtained iron granules decreased with an increase in rotating speed, cup diameter, slope angle, and cup depth. The disintegration mechanism of semisteel was determined, and the result indicated that the atomization process probably followed the ligament formation mode. A modified correlation that considered the influences of slope angle and cup depth was proposed to predictmedian granule size. An analysis on atomizer design was conducted based on these findings to provide a good insight for industrialization. As with RCA design for the treatment of molten semisteel rating up to 3.5 t/h, the minimum diameter of the rotary cup decreased from 1.36 m to 1.10 m as the rotary speed increased from 1200 rpm to 1800 rpm. (C) 2020 Elsevier B.V. All rights reserved.