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Gas Applications in the Paper Industryhttp://www.lindeus.com/en/industries/pulp_and_paper/index.html

Linde offers gas based solutions and unique technologies in the areas of pulp production, chemical recovery and paper production. Our products can help cost-conscious customers like the pulp and paper industry to realize their environmental aims. And our technology has been developed and proven around the world - from Scandinavia to Chile.

Bleaching of Chemical Pulp
The purpose of bleaching is to remove remaining dark-colored lignin impurities in the pulp and thus meet certain quality criteria.
Bleaching of chemical pulp is carried out in several stages. In modern mills, the bleaching starts with oxygen delignification for a reduction of the consumption of more expensive bleaching chemicals and a reduced effluent load from the bleach plant.

The predominant bleaching methods are ECF (elemental chlorine free) and TCF (totally chlorine free). In classic chlorine bleaching, molecular chlorine or chlorine gas are used with other chlorine-containing chemicals such as hypochlorite. For environmental and quality reasons other bleaching chemicals are replacing molecular chlorine and hypochlorite.

In TCF bleaching available chemicals for TCF bleaching are oxygen, hydrogen peroxide, ozone and peracids. In ECF bleaching chlorine dioxide is used with chlorine-free chemicals.

Pulp & Paper - Delignification
Oxygen delignification cleans wood fibers before they are actually bleached. It is a necessary method at pulp mills looking to eliminate chlorine-bleaching chemicals in the pulp production process, or to eliminate bleach plant effluents.
Oxygen delignification is also an economical alternative for the production of elemental chlorine-free pulp.

Ozone delignification is another economical alternative for eliminating, or partially replacing, the use of chlorine-containing chemicals.

Pulp & Paper - Bleaching
Oxygen in the actual bleaching process helps to further reduce costly and/or potentially harmful bleaching chemicals. And again, ozone bleaching is another economical alternative.