Purifying fibrous material, e.g. used paper pulp, in flotation chamber - in which impurities are absorbed in foam and removed by suction

摘要

Fibrous material such as pulp paper is purified and decolorised in a single flotation chamber. An air-laden suspn. of the pulp is introduced into the chamber, and is 'combed' by air bubbles in countercurrent flow in relation to the descending fibrous material. A foam, contg. the impurities, forms at the surface of the suspn., and is removed by suction. The purified material is removed from near the base of the chamber, and the air/water emulsion is returned for recycling. The number of purification stages in the appts. is reduced to a single flotation chamber, and the passage of particulate impurities into the improved prod. is prevented. The cost of installation of decolorising equipment is diminished. The equipment is easy to clean and requires minimal supervision.