To improve both of classification efficiency and classification accuracy by consisting of the plane shape of the apertures of respective holes of a slender shape having a first length in a longitudinal direction and a second length in a short side direction orthogonal with this longitudinal direction.
This filter for classification is constituted by forming apertures 2 of respective holes over an entire surface of a base plate 1. The plane shape of the apertures 2 of the respective holes of the filter consists of the slender shape (rectangular shape) having the first length (a) in the longitudinal direction and the second length (b) in the short side direction orthogonal with the longitudinal direction. The second length (b) in the short side direction of the respective holes has the grain size of the granular material to be classified or the length near the same. Further, the first length (a) in the longitudinal direction of the apertures 2 preferably has the length at which the particles failing to pass the apertures 2 are rollable or movable along the longitudinal direction of the apertures 2. More specifically, the ratio of the first (a) of the apertures 2 to the second length (b) is preferably ≥2, more preferably 100 to 1,000.
SEKIGUCHI FUMIO
MATSUO MAKOTO
NAKAMAE KATSUHIKO
