Process for treating pulp

Patent metadata

Field	Value
Publication number	US-11072886-B2
Application number	US-201716311213-A
Country	US
Kind code	B2
Filing date	Jun 27, 2017
Priority date	Jul 1, 2016
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

The present invention relates to a process for treating pulp comprising a step, wherein the pulp is treated with distilled percarboxylic acid, such as distilled per-carboxylic acid (dPAA), and peroxide, such as hydrogen peroxide.

First claim

The invention claimed is:

1. A process for treating pulp comprising subjecting the pulp to a post-bleaching step, wherein the pulp is treated with distilled percarboxylic acid and peroxide, wherein an amount of the peroxide, as 100% peroxide, is from 0.01 kg to 0.8 kg per ton of the pulp (as dry pulp), and wherein brightness of the pulp before the treatment is at least 75% ISO.

2. The process according to claim 1 , wherein the distilled percarboxylic acid is distilled performic acid, distilled peracetic acid (dPAA), distilled perpropionic acid, or a mixture thereof.

3. The process according to claim 1 , wherein the peroxide is hydrogen peroxide, percarbonate, or a mixture thereof.

4. The process according to claim 1 , wherein the pulp is wood pulp, chemical pulp, or Kraft pulp.

5. The process according to claim 1 , wherein an amount of the peroxide, as 100% peroxide, is from 0.04 kg to 0.6 kg per ton of pulp (as dry pulp).

6. The process according to claim 1 , wherein an amount of the distilled percarboxylic acid, as 100% distilled percarboxylic acid, is from 0.1 kg to 4 kg per ton of pulp (as dry pulp).

7. The process according to claim 1 , wherein a consistency of the pulp is from 2% to 30%.

8. The process according to claim 1 , wherein the pulp is treated at a temperature from 25° C. to 95° C.

9. The process according to claim 1 , wherein a treatment time is from 30 min to 120 h.

10. The process according to claim 1 , wherein a brightness of the pulp before the treatment is from 85% to 95% ISO.

11. The process according to claim 1 , wherein the distilled per-carboxylic acid and the peroxide are added at the same time.

12. The process according to claim 1 , wherein the distilled per-carboxylic acid is added first followed by addition of the peroxide.

13. The process according to claim 1 , wherein the peroxide is added first followed by addition of the distilled percarboxylic acid.

14. The process according to claim 1 , wherein the distilled per-carboxylic acid and peroxide are added as a mixture.

15. The process according to claim 1 , wherein pH value of the pulp before the treatment is from 3 to 9.

16. The process according to claim 1 , wherein an amount of the peroxide, as 100% peroxide, is from 0.06 kg to 0.5 kg per ton of pulp (as dry pulp).

17. The process according to claim 1 , wherein an amount of the distilled percarboxylic acid, as 100% distilled percarboxylic acid, is from 0.3 kg to 2 kg per ton of pulp (as dry pulp).

18. The process according to claim 1 , wherein a consistency of the pulp is from 5% to 15%.

19. The process according to claim 1 , wherein the pulp is treated at a temperature from 40° C. to 70° C.

20. The process according to claim 1 , wherein a treatment time is from 1 h to 24 h.

Assignees

• Kemira Oyj

Inventors

• Robertsén Leif
• Vuorenpalo Veli-Matti
• Perander Anna-Maija
• Pekonen Pentti
• Konn Jonas

Classifications

• D21C9/163

  with peroxides · CPC title

• D21C9/16

  with per compounds · CPC title

• D21C9/166 Primary

  with peracids · CPC title

• D21C9/1036 Primary

  Use of compounds accelerating or improving the efficiency of the processes · CPC title

• D21C9/10

  Bleaching {; Apparatus therefor} · CPC title