PNEUMATIC CLASSIFIER Russian patent published in 1994 - IPC

FIELD: pneumatic classification of friable materials. SUBSTANCE: pneumatic classifier comprises vertical round casing 1 accommodating overflow elements 6 and 7 in the form of coaxial cones and inverted hollow truncated cones. Installed coaxially in the casing is shaft 9 which carries scrapers 10, 11 for cleaning overflow elements 6, 7 of hanging and stuck material. Each underlying scraper is offset from the overlying one through an angle of α=600dn = 600d where d - casing diameter. The shaft speed is determined by the formula n < 0.05d. The feedstock is delivered through pipe 2 onto elements 6, 7, is uniformly distributed in the casing 1 and blown intensively by the ascending flow discharged from pipe 3. Coarse particles fall out through pipe 4 while the fine ones are carried away through pipe 5. Scrapers 10, 11 prevent hanging of material on overflow elements 6, 7 so that they stay constantly clean. Aggregations of stuck particles moving over elements 6, 7 strike repeatedly their clean and stiff surface and get destroyed. EFFECT: improved design. 3 dwg