GB1477326A - Method and apparatus for classifying paper fibres - Google Patents

Abstract

1477326 Classifying fibres BELOIT CORP 9 Sept 1974 [17 Sept 1973] 39280/74 Heading B2H Paper pulp fibres are classified according to length by directing a stream of fluid containing a mixture of the fibres in suspension against an edge of a separation member so that long fibres double over onto a portion of the edge of the member; moving the said edge portion of the member out of the stream; and removing the long fibres from the said edge portion after it has been moved out of the stream. In Fig. 1, a stream 11 of gaseous or liquid fluid containing a paper pulp fibre mixture is impelled by a pump 12 through a conduit 10 which directs the stream as a jet against the edge of a rotating disc 13. The long fibres are retained by the edge of the disc and are removed therefrom by a metal, rubber or plastics blade 16 so that they fall into a container 18. The unretained short fibres continue on past the disc in the stream as shown at 20. Instead of the blade 16, a rotating disc moving transverse to the direction of movement of the disc edge may be employed. Alternatively, the fibres may be removed from the edge by a jet of air which may be directed radially relative to the disc and which may serve as a carrier stream for conveying away the long fibres. A plurality of coaxial discs adjustably spaced from one another may be employed with a relatively broad fluid jet and the stream may be recirculated to further collect any long fibres which may have flowed past the discs. The discs may also be positioned in series with their widths narrowing in a downstream direction so that the first discs catch longer fibres than the succeeding discs. In Figs. 2 and 3, a wire or, as shown, a steel band 28 travels across a fibre suspension stream 26 flowing through a conduit 25. The long fibres collected on the leading edge 28b of the steel band are carried by the travelling band, e.g. via an adjustable opening 33, into a separation chamber 32 in which they are combed off the band by blades 35, 36 and carried through a discharge conduit 39 by means of a fluid stream directed into the chamber through a conduit 37 from a fan or pump 38. Multiple bands may be employed and additional multiuple stages may be provided downstream to collect additional fibres.