CO2 for paper Neutralisation

Improve the process using Carbon Dioxide for pH neutralisation.

Application of CO2 for paper mill production optimisation

We can find different phases in the paper production line where the use of CO2 for pH safe acidification leads to a relevant improvement by upgrading the drainage or recovering chemicals.

Washing delignified pulp

Lower the pH of the pulp to improve drainage.

Kraft pulp pH control

Replaces the strong acids to provide more consistent control.

Tissue paper pH control

CO2 can be used at the pH control of the pulp at two different points.

Flotation system improvement

Replace part of the compressed air with CO2 as a carrier gas during flotation.

PCC production

CO2 is used to produce precipitated calcium carbonate for the production of printing paper.

Kraft pulp pH control tower
 
Benefits
1
Reduce the pH of the
pulp to have better
draining.
2
Reduction of dilution
factor.
3
Increase content of
black solids.
4
Increase productivity.
In case the washed pulp goes to the bleaching process, CO2 also allows a reduction of the chlorinated agents used at the first stage, (CDO).

 

Replace strong acids
CO2 can also be used after the refining pulp process, to fine tune the pH level.
CO2 is generally used to replace strong acids (H2SO4), SO2 and aluminium sulphate, providing a smoother control, and avoiding great variations at the pH values. It allows a reduction of the consumption of aluminium sulphate dosed for pH control, which is, a partial substitution of the aluminium sulphate.
In plants that work with recycled paper as raw material

After bleaching with peroxide and NaOH, the CO2 is injected to adjust the pH level to values around 7.0 to avoid brightness reversion.

In mills that use cellulose as raw material

CO2 is used for the pH control of the pulp near the head box of the paper machine. This pH control provides a better draining performance at the wire in the paper machine.

Flotation System


CO2 is used in effluent treatment in flotation system to replace part of the compressed air used as a carrier gas during flotation (primary treatment of fiber recovery).


As CO2 has more affinity with the liquid phase than the air, so along the process it creates small bubbles, and improves flotation during the process, improving the flotation. Efficiency can be increased by around 15%. Usually, CO2 replaces from 40 to 60% of the total compressed air used.

PCC production

CO2 is used for PCC (Precipitated

Calcium Carbonate); production,

PCC is used as a filler in the alkaline sizing papers production (print paper).






 

Kraft pulp pH control tower.


CO2 is used to replace strong acids (HCO2 SO4 ), and aluminium sulphate providing a smoother control, it avoids great variation at the CO2 .

 

It's used before or after the refining process, aiming a thin adjustment of the pH level, and consequently, a reduction of the consumption of aluminium sulphate or sulfuric acid dosed for pH control, which is, total or parcial to neutral / alkaline sizing of paper.

CO2 control to press high consistency

Special packaging paper Bags.

(bags of cement, multi-wall bags).

 

COis used to eliminate aluminium sulphate providing a smoother control, and avoiding great variation of pH values. CO2 is used in high consistency press, aiming adjustment of the pH and, consequently improve the pulp drain-ability. The consistency expected is around 30%. A reduction on the consumption of aluminium sulphate dosed for pH control is significant. The mechanical properties of this type of paper are improved. This is very important for tear resistance of paper bags.

Form of supply
Tank
Liquid
CO2

Testing

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