Pulp/Paper: Peroxide Bleaching

Introduction:

Pulp & Paper

AQUAMAG® s advantageous in the peroxide bleaching of mixed office waste (MOW). In addition to a significant chemical cost savings, peroxide bleaching using AQUAMAG® can result in lower stickies production, reduced COD levels in the paper mill effluent, and improved runnability of the paper mill equipment.

AQUAMAG® provides 27% more alkalinity than caustic soda, as demonstrated in the following:

Mg(OH)2 → Mg2+ + 2 OH-
Molecular weight Mg(OH)2 = 58.3
2 NaOH → 2 Na+ + 2 OH-
Molecular weight NaOH = 80
1lb NaOH is equiv. to 0.73 lb’s of Mg(OH)2
1lb Mg(OH)2 is equiv. to 1.37 lb’s of NaOH


Comparison of Baseline Chemical dosages:

Typical MOW Peroxide Bleach Chemistry
NaOH - 0.9%
H2O2 - 1.0%
Na2SiO3 - 1.5%
Total Alkalinity – 1.0%
A/P ratio – 1.0
Low Alkaline Pulper Chemistry
Mg(OH)2 - 0.73%
H2O2 - 1.0%
Total Alkalinity – 1.0%
A/P ratio – 1.0

 

Unlike traditional peroxide bleaching techniques, AQUAMAG® can eliminate the need for Sodium Silicate (Na2SiO3) n the peroxide bleaching process. AQUAMAG® is a buffered source of alkalinity that can react with and precipitate transition metals. Much like Sodium Silicate, AQUAMAG® can effectively prevent the catalytic decomposition of Hydrogen Peroxide by transition metals. However - unlike Sodium Silicate - AQUAMAG® does not generate any unnecessary anionic by-products.

Caustic soda is very reactive and will disassociate into the hydroxide ion (OH-) almost instantaneously. This rapid dissociation creates a high pH environment and a rapid reaction with Hydrogen Peroxide (H2O2) – resulting in the formation of perhydroxyl ions (OOH-). The OOH- ions are very unstable and susceptible to metal-catalyzed decomposition. The catalytic decomposition of OOH- ions prematurely wastes Hydrogen Peroxide, and leads to inefficient bleaching. In the presence of Hydrogen Peroxide, AQUAMAG® progressively releases is OH- ions, creating a controlled reaction with Hydrogen Peroxide. This controlled reaction results in less OOH- decomposition and a more efficient usage of Hydrogen Peroxide.

Stickies and COD

Lowering the pH of the bleach tower may generate less stickies and COD in the mill effluent. The high-pH bleaching environment generated by caustic soda during alkaline bleaching can extract organics from the fiber and increase COD concentrations on mill effluent. Furthermore, this high-pH environment can also extract organics from glues and bindings found in the wastepaper, causing sticky deposits to accumulate on mill equipment and paper machines. AQUAMAG® produces a pH environment of approximately 9.0 – much lower than the pH environments created by the traditional bleaching technologies. Therefore, COD concentrations and sticky deposits are typically lower using AQUAMAG®. As a result, AQUAMAG® can lower the frequency of equipment cleanings and the downtime necessary to clean mill equipment, as well as improve machine performance and runnability on the whole.

Conclusions:

Low alkaline peroxide bleaching using AQUAMAG® is an efficient, cost effective alternative for bleaching of mixed office waste. In addition to lower chemical costs, AQUAMAG® can lower organic sticky deposits, COD concentrations, and significantly improve the performance and runnability of the paper mill equipment.

 

Please contact us for more information: Joe Brown - Sales Manager | David Martin - General Manager

acid neutralization bleaching pulp density premier storage resources gajshost about chemistry application aquamag https home hydroxide learn line issues hydrochloric httpwww httpsssl compare biological boiler articles applications additional brochure case documentlocationprotocol magnesium chemicals catcherr googleanalyticscomgajs natural synthetic system summary src sox specific testing treatment waste wastewater var try trial slurries sheets power presentations pagetrackertrackpageview organic metal works product proud responsible savings reagent quick pulppaper manufacturing