Abstract: A method and apparatus thickens lime mud with a disc filter in such a way that the precoat layer on the filter surfaces of the disc filter can be cleaned. Beneath the scrapers for scraping a dry layer of lime sludge from the precoat layers on the disc filter wires surfaces one or more high pressure nozzles, and optionally a low pressure nozzle, are provided for directing jets of liquid at the precoat layer and wire surface. One high pressure nozzle may remove the precoat layer while another cleans the wire surface, and the nozzles may be reciprocated (with respect to the shaft for rotating the disc filters in a trough). The high pressure jets provide liquid at a pressure of about 30-100 bar, while the low pressure jet pressure is between 2-30 bar and may be utilized continuously, or arrested when the high pressure jets are operable.

Abstract: The present invention concerns a floating bed reactor which is used for biological purification of fibre-containing liquid suspensions and for simultaneous clarification. The reactor comprises a floating bed (8) composed of finely divided particles floating in an ascending flow, above it being formed a fibre agglomerate layer (9) which binds to itself fibres present in the suspension being treated. What is essential in the invention is that the removal of fibre agglomerate from the reactor has been arranged with the aid of an open-top collecting vessel (11) placed in the reactor and disposed to collect fibre agglomerate in itself so that the top margin of the agglomerate layer (9) positions itself in the reactor substantially on level with the top end of the collecting vessel. The agglomerate then moves into the collecting vessel (11) by effect of a trailing vortex, for the generation of which the top end (13) of the vessel is bordered by a flow guiding member projecting laterally therefrom, or encircling it.

Abstract: The present invention concerns a feed and accept duct system (4) for hydrocyclones (1), comprising common feed and accept ducts (7,8) which have by connecting tubes been connected to the parallel hydrocyclones. This type of construction is used, for instance, in purifying fiber suspensions, in which process the suspension is fed into the hydrocyclones (1) and the purified suspension is removed therefrom as a so-called accept fraction into the accept duct (8).

Abstract: A lime sludge press unit comprising at least two pairs of press rolls, the lime sludge web passing, supported by an endless wire, through their press nips and moisture escaping from the lime sludge therein. After the first pair of rolls is located a lime sludge treatment screw transversal to the lime sludge web and which breaks up the pressed lime sludge web and carrying helical threads starting at its ends and opposite in direction so that these both transport the lime sludge from the margin of the web towards its center.