Abstract: A method for concentrating a suspension comprises the steps of providing a first surface; providing a second surface; introducing a suspension; moving the second surface relative to the first surface; and applying suction to the second surface. The first surface is relatively liquid-tight and includes a feature for increasing friction. The second surface is relatively liquid-pervious, faces the first surface, and is moveable relative to the first surface. Introduction of the suspension between the first and second surfaces forms a suspension web. Moving the second surface relative to the first surface and applying suction through the second surface causes dewatering of the suspension web and increased friction between the suspension web and the second surface.

Abstract: A fractionator for fractioning a suspension in at least two fractions, including a drum rotatable about a substantially horizontal access and having axially spaced end walls, a centrally arranged inlet for suspension, a flow channel for suspension in the drum, and outlets for fractions. The flow channel extends from the inlet back and forth between the end walls of the drum and radially outwards towards an outlet for the at least two fractions. Preferably the flow channel is defined by substantially concentric cylindrical walls of which every second wall is alternatively tightly connected to one or the other of the two end walls. The fractionator is useful in a continuous fractioning process.

Abstract: A method for controlling a filtration assembly wherein the amount of medium introduced into the filtration assembly is constant, even though the filterability of the medium or the condition of the filters has changed. The working cycle of the filtration assembly changes when the pressure difference across the filter mesh increases over a certain period of time. The control system is capable of distinguishing between the filterability of the medium introduced and the condition of the filter mesh.

Abstract: In a method for filtering a suspension through a stationary filter having a vertical filter element arranged in a pressure vessel and for re-conditioning the filter after filtering, the filtrate is discharged from the bottom of the filter element during the main part of the filtering. After filtering, unfiltered suspension is discharged in a known manner from the pressure vessel later to be returned to the suspension inlet. Thereafter, back-wash is performed with another medium other than filtrate, an outlet for material deposited on the filter element being opened for removal of said material together with the back-washing medium. Preferably, before back-wash, drying of the material deposited on the filter element takes place by means of a gas medium circulating within the filtering plant.