Oxygen Delignification

Intensive delignification with pure oxygen.

Delignification with oxygen reduces active chlorine requirements, environmental impact and water treatment operational costs.

Oxygen delignification enhances yield in bleached pulp production and offers relevant operating cost advantages over the use of bleaching agents. Not less important is the environmental benefits it leads to, mainly the minimisation of adsorbable organic halides (AOX). Also, oxygen application leads to lower wastewater treatment oxygen requirements and less color in effluent.

How oxygen delignification works
The process of lignin removal uses oxygen to reduce active chlorine requirements in the bleaching plant.
This process is an important step towards total chlorine free (TCF) and elemental chlorine free (ECF) in pulp production.
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Less environmental impact
Reduced or eliminated AOX production reducing environmental impact
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Lower cost
Lower overall bleaching chemical costs
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Lower BOD/COD
Lower BOD/COD production and less colour in the effluent
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Important bleaching
Important bleaching step towards TCF or ECF pulp production and mill closure
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Reduced wastewater
Reduced wastewater treatment costs (COD and colour removal)
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Better yield
Better yield than extended cooking

Oxygen in delignification

We can find different types of delignification processes: 

 

- HCOD - High Consistency Oxygen Delignification

 

- MCOD – Medium Consistency Oxygen Delignification
(following bullets within MCOD)
- Double Stage
- Single Stage
- Mini

 

- Pre – bleaching cellulose HCOD and MCOD
applications are well stablished technologies, adapted
to the concept of a modern plant

Slide to learn about Nippon Gases over time

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