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Abstract

The present invention relates to a method for producing pulp cooked under alkaline conditions, in which method cellulose-containing material is brought into contact, in a digester, with an alkaline cooking liquor containing dissolved potassium and sodium compounds, with used spent cooking liquor being separated off from the cellulose-containing material and withdrawn for the recovery of energy and chemicals, wherein: a) The molar ratio, calculated as K/K+Na, between potassium and sodium in a withdrawn spent cooking liquor exceeds 0.25. b) The withdrawn spent cooking liquor is concentrated with respect to its content of solid material and is subjected to partial oxidation in a reactor, resulting in the formation of a, combustible gas which is withdrawn from the reactor. c) oxygen-containing gas is supplied to the reactor in order to support the partial oxidation. d) The operating temperature in the reactor is adjusted to between 400.degree.-1200.degree. C. e) The combustible gas, which is obtained in association with the partial oxidation and which contains entrained solid and/or liquid alkali metal compounds, is separated from the major part of its content of alkali and used for the production of useful energy. f) The alkali metal compounds which have been separated off from the process gas are dissolved in liquid, which liquid is used either wholly or in part for preparing cooking liquor.

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First Claim