Process to obtain fully oxidized white liquor for use in the fiberline of a kraft pulp process
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l’Exploitation des Procedes Georges Claude
InventorsOliveira ARAUJO, Philippe CAMPO, Jukka ISOMETSA, Bruno ALBAN
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Abstract
The present application relates to a process to obtain fully oxidized white liquor from white liquor used in a Kraft pulp process. Said fully oxidized white liquor is suitable to be used in alkaline steps of certain stages of the Kraft pulp process fiberline in order to partly or totally substitute the purchased sodium hydroxide used in those stages. The presently disclosed process also allows to purge non-process elements (NPE's) by purging alkaline wash filtrates to a wastewater treatment plant.
Claims10
A process to obtain fully oxidized white liquor for use in the fiberline of a Kraft pulp process characterized by comprising the following steps:
- Oxidizing between 1 and 100 m3/h of white liquor from the Kraft pulp process with oxygen, obtaining fully oxidized white liquor comprising NaOH, Na2SO4, Na2CO3 and Na2S2O3;
- Feeding the fully oxidized white liquor to the bleaching stages and/or the delignification stages and/or the alkaline extraction stages of the Kraft pulp process;
- Purging non-process elements by purging the filtrates from washing steps after the bleaching stages and/or alkaline extraction stages to a Wastewater Treatment Plant;
- Feeding up to 100% of the alkaline filtrate obtained in the washing steps after the bleaching stages to an evaporation plant;
- Feeding the alkaline filtrate obtained in the washing steps after the delignification stages to the evaporation plant;
- and
- Purging non-process elements from a recovery boiler in the Kraft chemical recovery process of the Kraft pulp process.
Dependencies are inferred from the claim text.