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AssigneeA. Ahlstrom Corporation
InventorsKaj Henricson, Olavi Pikka, Aki Vilpponen, Nils-Erik Virkola
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The present invention relates to a method of intensifying the washing of a fiber suspension. In particular, the present invention relates to decreasing the lignin content of a fiber suspension by extracting. Lignin removal is usually carried out at a consistency of less than 3% whereby heating consumes much energy. The method of the invention allows a considerable increase in the consistency of the suspension which results in that the energy consumption is decreased to a fraction of the one required by prior art methods. A characteristic feature of the method of the invention is that dry substance and chemicals contained in the fibers are extracted at a raised pressure and temperature.
A method of intensifying washing of a fiber suspension after digestion, said suspension containing residual alkali in a way so as to preserve the strength properties of fibers in said fiber suspension so that they are the same before washing and after washing, comprising the steps of:
Dependencies are inferred from the claim text.