VERFAHREN UND VORRICHTUNG ZUM ENTFERNEN VON VERUNREINIGUNGEN AUS ALTPAPIER.

摘要

In a process for de-inking or removing printing ink from waste paper, the prepared suspension of fibres is initially given flotation treatment for a short period, i.e. for example for two minutes, in a single-stage flotation unit (2) and then subjected to washing in one or more washing stages (7) in such a way that a hydrocyclone (classifier) (6) can be connected in-line between the two cleaning stages. The rejects from all stages are led without intermediate cleaning to a common internal waste water cleaning unit (clarifier) (4), which separates the rejects into thick sludge, thick sludge filtrate and clarified water. The clarified water and also, if desired, the filtrate from the sludge press are used again in the system as process water. The process is particularly suitable for the removal of electro-static inks (laser inks), which are difficult to remove and permits the production in a simple way of a paper of particularly good cleanliness from waste paper, accompanied by the most sparing consumption of water.