Abstract: A method and a liquor filter, in which liquor filter sealing medium is fed via a sealing medium channel (3) into an innermost sealing zone formed by an innermost sealing member (1), an outer seal (2) and the space between them at a causticizing plant of a chemical pulp mill. The sealing medium used is an alkaline sealing liquid and/or gas, which does not substantially dilute the liquor being filtered. Advantageously the sealing medium is filtrate from the liquor filter and/or gas taken from the interior of the liquor filter.

Abstract: Method and apparatus for reducing the thickness of a precoat-layer accumulated on the filtering surface of a filter disc from a solids-containing suspension in a basin of a disc filter, said disc filter having two or more filter discs arranged on a shaft and between them at least one drop chute provided with a scraper on both sides, which scraper scrapes the cake filtered from the suspension on the filtering surfaces of the filter discs into the drop, the layer thickness of the precoat on the filtering surface is reduced by shortening the distance between the tips of the scrapers and the filtering surface, and the precoat thickness reduction is accomplished for the precoats on the filtering surface of the two filter discs on both sides of the drop chute non-simultaneously.

Abstract: Method and apparatus for reducing the thickness of a precoat-layer accumulated on the filtering surface of a filter disc from a solids-containing suspension in a basin of a disc filter, said disc filter having two or more filter discs arranged on a shaft and between them at least one drop chute provided with a scraper on both sides, which scraper scrapes the cake filtered from the suspension on the filtering surfaces of the filter discs into the drop, the layer thickness of the precoat on the filtering surface is reduced by shortening the distance between the tips of the scrapers and the filtering surface, and the precoat thickness reduction is accomplished for the precoats on the filtering surface of the two filter discs on both sides of the drop chute non-simultaneously.