GB1086619A - Process and apparatus for the thickening of slurries - Google Patents

Abstract

1,086,619. Rotary drum filter. CANADIAN INGERSOLL RAND CO. Ltd. March 3, 1965, No. 9044/65. Heading B1D. The drum of a rotary drum filter comprises two concentric cylindrical screens 22, 24, incoming slurry being delivered by pipe 18 to the closed end 28 of inner screen 22 whereby some filtrate is drawn off, the thickened slurry then passing out of the open end of screen 22 into a surrounding vat 12 for further filtration by outer screen 24 on which a filter cake builds up, the filtrates passing outwards through screen 22 and inwards through screen 24 being withdrawn from the annular space between the screens to outlet 20. In Fig. 2 the two filtrates are mixed, but in Fig. 5 (not shown) the annular space is divided by a cylindrical wall and the two filtrates are withdrawn separately. In Fig. 2 a spray head 50 directs water under pressure on to the inside of screen 22 above the slurry level to remove deposit therefrom. In Fig. 4 (not shown) the annular space between the screens is fitted with spaced scoops which lift and empty filtrate back through screen 22 as the drum rotates, which arrangemeat may replace or supplement spray head 50. Filter cake is removed from outer screen 24 by a couch roll (58) and coacting blade (60), (Fig. 3, not shown). The drum is supported by rollers 38, 39 engaging inside and outside of drum end flanges 34, 36, and is rotated by motor 46 driving a gear 44 which engages internal gear ring 42 of flange 34. Sealing ring 48 on end wall 16 of vat 12 engages rotating flange 36. The inner screen 22 may be of wire mesh finer than outer screen 24, and where separate filtrates are obtained the cloudy filtrate from screen 22 may be recirculated.