GB1034089A - Extraction apparatus and method - Google Patents

Abstract

1,034,089. Pulverizing apparatus; centrifugal separators. MICROCYCLOMAT CO. May 19, 1965, No. 21244/65. Headings B2A and B2P. Apparatus for removing coarse and dense impurities &c. from non-metallic solid materials comprises an air attrition mill and an integral classifier. The apparatus comprises a first cylindrical vertical casing 10, Fig. 4, which has an open top communicating with a second cylindrical vertical casing 36 of greater diameter and less axial depth mounted on top of the first casing. An involute scroll fan housing 43 containing a fan rotor 47, 48 is mounted on top of the second casing and a vertical axis shaft 20, rotatably journaled at 21, 22 and extending centrally through the casings and housings and driven by a motor 12, Fig. 1 (not shown), and pulleys 23. Stacked grinding rotor stages are mounted on the shaft for rotation in the first casing, and each stage includes a horizontally disposed disc 31 with spaced vertical radial blades 32 around its periphery and an annular disc 34 between each pair of stages. A material inlet fed by a screw from a hopper 14 is adjacent to lower most stage and an air inlet 28 having a regulator 30 is provided to the bottom 29 of the first casing. An auxiliary fan 26, 27 is mounted on the shaft between the air inlet and the lowermost of the grinding rotor stages. A classifier rotor is mounted on the shaft for rotation in the second casing, and comprises a horizontal disc formed of plates 39, 40 spaced by a ring 41 and horizontal radial finger-like blades 42 uniformly distributed and extending around the periphery of the discs. A horizontally disposed diaphragm ring 44 is mounted between the second casing and the fan housing and is of smaller diameter than the classified rotor disc. An extraction post and conduit 51 is provided in the second casing below the level of the classifier disc. In operation material is screw fed into the reducing chamber 10 and the finer material passes into the classified housing 36 where it is freed from coarser materials, passes between the blades 42 and is drawn through a narrow passage 50 between the inner lips of the diaphragm ring 44 and the outer lips of the plate 40. The material is discharged from a conduit 49, Fig. 1 (not shown). Coarser materials are rejected by the rotor and thrown centrifugally outwards to the cylindrical wall of the housing 36 and are caught by one of a number of coarse extraction conduits 51. One end of each conduit communicates with a passage 52 in the wall of the classifier housing 36 and the opposite end includes a resilient flapper valve 53 which opens when sufficient coarse material has accumulated. A further embodiment includes a cyclone in place of the flapper valve. Separated air and fines may be recirculated via a conduit 62, Fig. 5 (not shown) .