Method for producing water-absorbent resin powder and production apparatus therefor

A method for producing water-absorbent resin powder, the method comprising:

• a gel-crushing step of grinding a crosslinked hydrogel polymer to obtain a particulate crosslinked hydrogel polymer;
• a heating drying step of obtaining dried particles from the particulate crosslinked hydrogel polymer by using a continuous stirring drying machine;
• a post-crosslinking step of post-crosslinking the particulate crosslinked hydrogel polymer or the dried particles;
• and
• a sizing step of adjusting a particle size of the dried particles or the post-crosslinked dried particles to obtain water-absorbent resin powder, wherein
• the particulate crosslinked hydrogel polymer in the heating drying step contains a gel fluidizer,
• a gel temperature of the particulate crosslinked hydrogel polymer containing the gel fluidizer, the gel temperature being measured by a contact thermometer, is not lower than 50° C.,
• the dried particles or the post-crosslinked dried particles is forcedly cooled before the sizing step,
• the particulate crosslinked hydrogel polymer has a mass-average particle diameter d1 in terms of dry weight is not greater than 800 μm before drying, and
• the continuous stirring drying machine comprises a rotary drying machine having one or more heating means that are selected from a through-flow heating type, an outer wall heating type, and a tubular heating type.