GB/T 6609.27-2023 "Chemical Analysis Methods and Physical Property Determination of Alumina - Part 27: Particle Size Analysis - Sieving Method" specifies the applicable scopes of three sieving methods for determining the particle size distribution of alumina. The dry sieving method, wet sieving method, and solvent flushing method correspond to samples with different particle size proportions. The core instruments include standard test sieves with apertures ranging from 16 μm to 63 μm, a standard sieve shaker, as well as supporting weighing and flushing equipment. Through sieving classification and weighing, the proportion of particles in different particle size ranges is determined, providing data support for adjusting alumina production processes and adapting to downstream applications.