Canadian Patents Database / Patent 2214957 Summary

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(12) Patent Application: (11) CA 2214957
(54) English Title: PROCESS TO PRODUCE BRIGHT PULP IN AN ELECTROCHEMICAL REACTOR
(54) French Title: PROCEDE POUR PRODUIRE DE LA PATE BLANCHE DANS UN REACTEUR ELECTROCHIMIQUE
(51) International Patent Classification (IPC):
  • D21C 9/10 (2006.01)
  • D21C 9/16 (2006.01)
(72) Inventors (Country):
  • DANEAULT, CLAUDE (Canada)
  • ROBERT, SYLVAIN (Canada)
  • SAIN, MOHINI MOHAN (Canada)
(73) Owners (Country):
  • DANEAULT, CLAUDE (Canada)
  • ROBERT, SYLVAIN (Canada)
  • SAIN, MOHINI MOHAN (Canada)
(71) Applicants (Country):
  • DANEAULT, CLAUDE (Canada)
  • ROBERT, SYLVAIN (Canada)
  • SAIN, MOHINI MOHAN (Canada)
(74) Agent:
(45) Issued:
(22) Filed Date: 1997-11-05
(41) Open to Public Inspection: 1999-05-05
Examination requested: 1997-11-05
(30) Availability of licence: N/A
(30) Language of filing: English

English Abstract



A process has been developed to bleach pulp in-situ by passing current in an electrolyte
solution capable to generate oxidising bleaching chemicals. Using a rotative stainless steel
cathode and a platinum anode in a carbonate-borate-tetraacetylethylenediamine
electrolyte solution, adding pulp to the said solution and then carrying out electrolysis
between 5 to 80°C with an anode current density between 0.1 to 6 kA/m2, a bleached pulp
with improved brightness was obtained. The rotation of the electrode and recirculation of
pulp slurry in the electrochemical cell were particularly suitable for pulp concentration
above 2 parts of dry pulp per 100 parts of electrolyte solution.


Note: Claims are shown in the official language in which they were submitted.

The subject matter which applicants regard as their invention is particularly pointed out
and distinctly claimed as follows:

1. A process for the brightening of delignified Kraft pulp from lignocellulosic material
which comprises treating said lignocelluloic material in an electrolyte solution
containing sodium carbonate, borax, sodium bicarbonate and balance water, said
electrolyte solution having a pH of about 10 and pulp in the said electrolyte solution is
of 0.5 to 6% constancy, by weight of oven dried pulp, wherein the said electrolyte is
undergoing a continuous electrolysis under a current density ranging between about



0.2 to about 6.0 kA/m2 and a temperature of about 6°C. to about 80°C. in the presence
or absence of tetraacetylethylenediamine, compound capable of producing peracetic
acid in-situ in the electrolytic cell, the said electrolysis cell is provided with a rotative
stainless steel cathod to aid mixing of pulp and a pump to circulate the pulp slurry in
the said electrolyte solution.
2. A process as defined in claim 1 wherein the pulp slurry is a homogeneous mixture of
delignified Kraft pulp, electrolytes and chemicals generated in-situ during electrolysis
and balance water to make up the consistency.
3. A process as defined in claim 1 wherein the delignified Kraft pulp is a softwood Kraft
pulp.
4. A process as defined in claim 1 wherein the stainless steel cathod has sufficient surface
area to mix pulp slurry and provides adequate mixing to prevent deposition of pulp on
cathode and anode surfaces.
5. A process as defined in claim 1 wherein the platinum anode is separated from the
cathode by a specific barrier membrane.
6. A process as defined in claim 1 wherein the tetraacetylethylenediamine compound is
soluble in alkaline solution.
7. A process as defined in claim 6 wherein the said tetraacetylethylenediamine compound
is capable to react with sodium perborate or hydrogen peroxide generated in-situ in the
pulp slurry.
8. A process as defined in claim 1 wherein the said compound tetraacetylethylenediamine
is consumed by the said in-situ electrochemically generated perborate or peroxide to
produce peracetic acid.
9. A process as defined in claim 1 wherein the said generated peracetic acid has improved
brightening effect on the delignified pulp.



10. A process as defined in claim 1 wherein the electrolysis temperature is between 10°C. to
80°C.
11. A process as defined in claim 1 wherein the electrolysis time is between 30 min. to 150
min.
12. A process as defined in claim 1 wherein the delignified pulp material is pre-treated
with 0.5% DTPA.


A single figure which represents the drawing illustrating the invention.

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Admin Status

Title Date
(22) Filed 1997-11-05
Examination Requested 1997-11-05
(41) Open to Public Inspection 1999-05-05
Dead Application 2002-10-15

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $200.00 1997-11-05
Filing $150.00 1997-11-05
Reinstatement: Failure to Pay Application Maintenance Fees $200.00 2000-06-12
Maintenance Fee - Application - New Act 2 1999-11-05 $50.00 2000-06-12
Maintenance Fee - Application - New Act 3 2000-11-06 $50.00 2000-10-10
Maintenance Fee - Application - New Act 4 2001-11-05 $50.00 2001-09-10
Maintenance Fee - Application - New Act 5 2002-11-05 $75.00 2002-09-11

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Document
Description
Date
(yyyy-mm-dd)
Number of pages Size of Image (KB)
Description 1997-11-05 21 828
Representative Drawing 1999-05-20 1 15
Claims 1997-11-05 3 67
Drawings 1997-11-05 1 31
Abstract 1997-11-05 1 23
Representative Drawing 2007-02-05 1 23
Cover Page 1999-05-20 1 60
Fees 1999-12-03 2 98
Fees 2002-09-11 1 69
Fees 2001-09-10 2 91
Correspondence 1997-11-14 1 17
Prosecution-Amendment 2001-06-15 3 96
Fees 2000-06-12 2 105
Fees 2000-10-10 1 68