GB413294A - Improvements in and relating to the separation of dust and fine material from powdered or granular material especially coal - Google Patents

Abstract

413,294. Pneumatic separating. ALLEN, R. H., 19, Makepeace Avenue, Highgate, London. Jan. 11, 1933, No. 975. [Class 117.] In apparatus for separating dust or fine particles from a mixture of particles of different sizes, of the kind which comprises an elongated sloping separating chamber, the lower side of which has apertures for the entrance of air or other gas, which carries away the finer particles from the mixture as it slides thereover, the lower side 2 of the chamber 1 is curved with the convex side uppermost. Preferably the radius of curvature increases from the top to the bottom so as to approximate the path of freely falling material and the feed shoot 7 is tangential to the upper end of the side 2. The air is introduced under the side 2 by a conduit 11 with a regulating valve 12, and a baffle 13 may be provided for regulating the distribution of the air as between the upper and lower parts of the side. A supplementary air current may be introduced at the bottom end 9 of the chamber by means of the conduit 14 and valve 15, and a baffle 16 may be provided in this conduit for smoothing the flow of air. In the construction described, the side 2 is formed of overlapping metal plates which may be adjustable and be provided with air-directing wooden blocks 3, 4. The top side 41 of the chamber is curved to follow generally the contour of the lower side but is preferably spaced at an increasing distance therefrom towards the upper end of the chamber, and provided with a manhole cover 21 and inspection window 22. The lower discharge end of the chamber is provided with baffles 19 to break the fall of the dedusted material and rubber linings may be provided for the plates 2, and the inlet and outlet ducts of the chamber. The dust laden air passes up the conduit 8 into a classifying duct 23 in which an intermediate grade of particles is deposited either for separate removal or return to the separating chamber. This duct may be curved as shown and the upper side is formed of two hinged interleaved plates 24, 25 which are adjusted in position by a screw 28 to vary the cross-section of the duct. Deflectors 31 are provided on the lower side of the duct to guide the deposited material to the corners of the duct out of the main air current. The air from the classifier is passed through dust settling apparatus such as described in Specifications 411,121, 411,122, and 411,123, and may be returned to the fan in a closed circuit or into the atmosphere. Air flow indicators may be fitted at required points, and the apparatus may be associated with a device for screening out the large pieces from the raw material. When damp material is being treated, heated air or gas is used and discharged into the atmosphere.