Eka Nobel Ab

Mats G Nystrom

Bernt Larsson

Kenneth O Larsson

Solvie M Herstad

Wolgang Herrmann

Anna K Skogby

Silica particles which are substantially spherical, have a particle size of 1 to 100 .mu.m, a very narrow pore size distribution and a low alkali metal content. The particles can be prepared by sol-gel technique using emulsification technique for drop formation. The process comprises a sol growth step in a basic environment based on ammonium or amines and a post-treatment in such an environment. The silica particles are particularly suitable for use in chromatography as they have very good particle and porosity properties and high purity.

Method for preparation of silica particles

The present invention relates to a method of reducing the content of halogenated organic compounds in the spent bleach liquor from the bleaching of lignocellulose-containing material with compounds containing halogen, wherein the spent bleach liquor, in a stage where no essential delignification or bleaching of the pulp takes place, is maintained at a pH of from 2.5 up to about 10, and wherein the residence time and the temperature are selected such that the amount of dissolved halogenated organic substances in the spent bleach liquor is reduced by at least 30%.

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Ytterby, Sweden

Mats G Nystrom