US3657065A - Delignification and bleaching of cellulose pulp with oxygen gas in an allsaline medium in the presence of a protector - Google Patents
Delignification and bleaching of cellulose pulp with oxygen gas in an allsaline medium in the presence of a protector Download PDFInfo
- Publication number
- US3657065A US3657065A US832477A US3657065DA US3657065A US 3657065 A US3657065 A US 3657065A US 832477 A US832477 A US 832477A US 3657065D A US3657065D A US 3657065DA US 3657065 A US3657065 A US 3657065A
- Authority
- US
- United States
- Prior art keywords
- pulp
- protector
- magnesium
- earth metal
- alkaline earth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000001012 protector Effects 0.000 title claims abstract description 43
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 title abstract description 16
- 229910001882 dioxygen Inorganic materials 0.000 title abstract description 16
- 238000004061 bleaching Methods 0.000 title abstract description 11
- 239000001913 cellulose Substances 0.000 title abstract description 9
- 229920002678 cellulose Polymers 0.000 title abstract description 9
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 36
- 238000000034 method Methods 0.000 claims abstract description 28
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims abstract description 9
- 239000000347 magnesium hydroxide Substances 0.000 claims abstract description 9
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims abstract description 9
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000004115 Sodium Silicate Substances 0.000 claims abstract description 7
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 7
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052911 sodium silicate Inorganic materials 0.000 claims abstract description 7
- 239000000391 magnesium silicate Substances 0.000 claims abstract description 6
- 229910052919 magnesium silicate Inorganic materials 0.000 claims abstract description 6
- 235000019792 magnesium silicate Nutrition 0.000 claims abstract description 6
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 6
- SPAGIJMPHSUYSE-UHFFFAOYSA-N Magnesium peroxide Chemical compound [Mg+2].[O-][O-] SPAGIJMPHSUYSE-UHFFFAOYSA-N 0.000 claims description 3
- 229960004995 magnesium peroxide Drugs 0.000 claims description 3
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 8
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 abstract description 6
- 239000000463 material Substances 0.000 abstract description 6
- 229910052749 magnesium Inorganic materials 0.000 abstract description 5
- 239000011777 magnesium Substances 0.000 abstract description 5
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 abstract description 5
- 239000001095 magnesium carbonate Substances 0.000 abstract description 5
- 229910000021 magnesium carbonate Inorganic materials 0.000 abstract description 5
- ZADYMNAVLSWLEQ-UHFFFAOYSA-N magnesium;oxygen(2-);silicon(4+) Chemical compound [O-2].[O-2].[O-2].[Mg+2].[Si+4] ZADYMNAVLSWLEQ-UHFFFAOYSA-N 0.000 abstract description 5
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 abstract description 4
- 229910052784 alkaline earth metal Inorganic materials 0.000 abstract description 4
- 229910000316 alkaline earth metal phosphate Inorganic materials 0.000 abstract description 4
- 150000001342 alkaline earth metals Chemical class 0.000 abstract description 4
- 150000003839 salts Chemical class 0.000 abstract description 4
- 239000000377 silicon dioxide Substances 0.000 abstract description 4
- 229910052910 alkali metal silicate Inorganic materials 0.000 abstract description 3
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 abstract description 3
- 229910052915 alkaline earth metal silicate Inorganic materials 0.000 abstract description 3
- 238000011065 in-situ storage Methods 0.000 abstract description 3
- GVALZJMUIHGIMD-UHFFFAOYSA-H magnesium phosphate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O GVALZJMUIHGIMD-UHFFFAOYSA-H 0.000 abstract description 3
- 239000004137 magnesium phosphate Substances 0.000 abstract description 3
- 229910000157 magnesium phosphate Inorganic materials 0.000 abstract description 3
- 229960002261 magnesium phosphate Drugs 0.000 abstract description 3
- 235000010994 magnesium phosphates Nutrition 0.000 abstract description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 10
- 239000001301 oxygen Substances 0.000 description 10
- 229910052760 oxygen Inorganic materials 0.000 description 10
- 235000011121 sodium hydroxide Nutrition 0.000 description 9
- 239000000706 filtrate Substances 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 4
- 239000000460 chlorine Substances 0.000 description 3
- 150000001805 chlorine compounds Chemical class 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- UDHXJZHVNHGCEC-UHFFFAOYSA-N Chlorophacinone Chemical compound C1=CC(Cl)=CC=C1C(C=1C=CC=CC=1)C(=O)C1C(=O)C2=CC=CC=C2C1=O UDHXJZHVNHGCEC-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 239000007844 bleaching agent Substances 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000002655 kraft paper Substances 0.000 description 2
- 229920005610 lignin Polymers 0.000 description 2
- 229910001629 magnesium chloride Inorganic materials 0.000 description 2
- 229910052914 metal silicate Inorganic materials 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 1
- 235000011613 Pinus brutia Nutrition 0.000 description 1
- 241000018646 Pinus brutia Species 0.000 description 1
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- FMRLDPWIRHBCCC-UHFFFAOYSA-L Zinc carbonate Chemical compound [Zn+2].[O-]C([O-])=O FMRLDPWIRHBCCC-UHFFFAOYSA-L 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- -1 alkali metal borates Chemical class 0.000 description 1
- AYJRCSIUFZENHW-DEQYMQKBSA-L barium(2+);oxomethanediolate Chemical compound [Ba+2].[O-][14C]([O-])=O AYJRCSIUFZENHW-DEQYMQKBSA-L 0.000 description 1
- 238000010009 beating Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- UEGPKNKPLBYCNK-UHFFFAOYSA-L magnesium acetate Chemical compound [Mg+2].CC([O-])=O.CC([O-])=O UEGPKNKPLBYCNK-UHFFFAOYSA-L 0.000 description 1
- 239000011654 magnesium acetate Substances 0.000 description 1
- 235000011285 magnesium acetate Nutrition 0.000 description 1
- 229940069446 magnesium acetate Drugs 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 150000004692 metal hydroxides Chemical class 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000000123 paper Substances 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000011667 zinc carbonate Substances 0.000 description 1
- 229910000010 zinc carbonate Inorganic materials 0.000 description 1
- 235000004416 zinc carbonate Nutrition 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1026—Other features in bleaching processes
- D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes
Definitions
- ABSTRACT A method of delignifying and bleaching a chemical or semichemical cellulose pulp with oxygen gas in an alkaline medium, preferably sodium hydroxide, and in the presence of a protector, the method being characterized in that the protector is selected from the group consisting of silica; an alkali metal silicate, such as sodium silicate; an alkaline earth metal silicate, such as magnesium silicate; an alkaline earth metal phosphate, such as magnesium phosphate; an alkaline earth metal oxide, such as magnesium oxide; an alkaline earth metal peroxide; an alkaline earth metal hydroxide or a material forming an alkaline earth metal hydroxide, such as magnesium hydroxide or a material forming magnesium hydroxide in situ; and a soluble salt of magnesium other than magnesium carbonate.
- the protector is selected from the group consisting of silica; an alkali metal silicate, such as sodium silicate; an alkaline earth metal silicate, such as magnesium silicate; an alkaline earth metal phosphate, such as magnesium
- oxygen gas includes any other gas containing free oxygen, such as air.
- the catalyst or protector may be selected from a new group. Many of these new protectors have the great advantage of more efiectively preserving the physical strength properties of cellulose pulps, and even of improving them in some cases, than certain of the known protectors, while giving a significant increase in brightness.
- the protector may be selected from the group consisting of silica; and alkaline metal silicate, such as sodium silicate; an alkaline earth metal silicate, such as magnesium silicate; an alkaline earth metal phosphate, such as magnesium phosphate; an alkaline earth metal oxide, such as magnesium oxide; an alkaline earth metal peroxide, such as magnesium peroxide; an alkaline earth metal hydroxide or a material forming an alkaline earth metal hydroxide, such as magnesium hydroxide or a material forming magnesium hydroxide in situ; and a soluble salt of magnesium, such as magnesium acetate or magnesium chloride.
- alkaline metal silicate such as sodium silicate
- an alkaline earth metal silicate such as magnesium silicate
- an alkaline earth metal phosphate such as magnesium phosphate
- an alkaline earth metal oxide such as magnesium oxide
- an alkaline earth metal peroxide such as magnesium peroxide
- Sodium silicate, magnesium oxide, magnesium hydroxide and magnesium silicate are particularly advantageous.
- the new protectors give the best results when used at a concentration from 0.5 to about 3 percent preferably 1 percent, by weight of the pulp on a dry basis.
- alkaline medium preferably sodium hydroxide.
- the sodium hydroxide content may vary from 2 to 12 percent by weight on a dry pulp basis depending on the degree of delignification and bleaching that is required.
- the quantity of sodium hydroxide required may be increased for untreated pulps with a high lignin content.
- the oxygen gas treatment is best carried out in any suitable pressure apparatus which will ensure intimate contact or adequate exposure of the pulp mass with or to oxygen in the gas phase.
- the pulp consistency may be in the range from 4 to 30 percent by weight, preferably 7 to 25 percent percent.
- an untreated alkaline pulp is treated with sodium hydroxide in the presence of the protector with oxygen gas in a pressure vessel at an elevated operating temperature, preferably between 90 and C, and at an elevated partial pressure at the maximum operating temperature, preferably in the range 70 to p.s.i.g.
- the pressure need only be limited by the characteristics of the apparatus used.
- the pulp may be subjected to the oxygen treatment at the maximum operating temperature for a period of time ranging from 10 to 120 minutes, depending on the results required or the nature of the pulp being treated.
- the pulp may be washed in any suitable manner.
- the choice of the washing operation is largely governed by whether recovery of chemicals in the effluent or subsequent bleaching is contemplated. It is advantageous for the washing operation to be done carefully and for the effluent to be treated in a chemical recovery process. Further economies in recovery of this filtrate can be achieved if a portion of this filtrate is used for dilution of pulp which is to be oxygen gas treated. This has been found to have no deleterious efiects on the brightnesses obtained.
- Such filtrate, or recirculated filtrate may then, for example, be used as portion of the wash water used in the normal washing stages applied to the pulp as produced by the pulping process concerned, or may be added directly to the liquors at any stage in the recovery process concerned.
- the caustic soda in the filtrate may be recovered by any of the known methods of recovery. It is a big advantage of this process that despite the load of organic matter in these filtrates, they are substantially free of chlorides which are normally always present in bleach plant effluents, apart from any chloride that might be introduced when the protector contains the element chlorine.
- the concentrations are given as percentages by weight on a dry pulp basis, except for sodium silicate, the amount of which is based on the solids content of the commercial product.
- the oxygen pressures are those pertaining at the temperature stated.
- Pulp consistency is the ratio, expressed as a percentage, of the weight of the dry pulp to the weight of the wet pulp. All tests for the examples were carried out in accordance with TAPPI or AFNOR specifications.
- Pulp A a. untreated, unbleached, resinous Kraft pulp
- Pulp B the pulp of (a) above after oxygen gas treatment in an alkaline medium without a protector
- Pulp C the pulp of (a) above after oxygen gas treatment in an alkaline medium in the presence of magnesium carbonate which is the preferred protector disclosed in our French Patent Specification No. 1,387,853, (hereinafter referred to as Pulp C).
- Pulps D.,E.F. and G different batches of the pulp of (a) above after oxygen gas treatment in alkaline medium in the presence of different protectors according to the present invention (hereinafter referred to as Pulps D.,E.F. and G respectively.)
- Pulps D,E,F and G which have been treated in the presence'of protectors according to the present invention, have higher brightnesses than pulps AB and C. It
- a method of delignifying and bleaching a chemical or semi-chemical cellulose pulp consisting essentially of subjecting the pulp to treatment with oxygen gas in an EXAMPLE H alkaline medium in the presence of up to 3 percent by weight I of a protector which is operative to inhibit degradation of the The hgnin content, the brightness and the physical strength physical and mechanical strength properties of the pulp and properties of the following pulps are compared in Table II which comprises a substance other than that constituting the below: 1 O alkaline medium, said protector being selected from the group a.
- Untreated unbleached, pine kraft pulp hereinafter consisting of silica; an alkali metal silicate; an alkaline earth referred to as Pulp H) metal silicate; an alkaline earth metal phosphate; an alkaline b.
- kaline earth metal hydroxide hereinafter referred kaline earth metal hydroxide
- Pulp I soluble salt of magnesium
- a method as claimed in claim 1 wherein the protector (hereinafter referred to as Pulps J and K respectively) comprises magnesium oxide. It will be seen that the brightnesses of Pulps J and K which 4.
- the protectors used on pulps comprises magnesium hydroxide. .l and K effectively preserve the physical strength properties of 6.
- a method as claimed in claim 1, wherein the protector the pulp and even improves them in certain respects. comprises magnesium peroxide.
- a method as claimed in claim 1, wherein the protector is Pulp H I J K 45 used at a concentration of from 0.5 to 3 percent by weight on a dry pulp basis. Pulp consistency 17 15 17 Alkaline medium (percent NaOH per- 8. A method as claimed in claim 1, wherein the alkaline cent) 6 5 6 Protector, percent N11 i 2) medlum compnses Soqmm h x Oxygen pressure at maximum operat- 9. A method as claimed in claim 7, wherein the protector ing temp., p.s.i. gauge 170 170 170 Maximum operating temp. C.) 130 130 130 compnses 1 percent by W l on a pulp Time at maximum operating tempera- 10.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA683771 | 1968-06-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3657065A true US3657065A (en) | 1972-04-18 |
Family
ID=25561209
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US832477A Expired - Lifetime US3657065A (en) | 1968-06-13 | 1969-06-11 | Delignification and bleaching of cellulose pulp with oxygen gas in an allsaline medium in the presence of a protector |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US3657065A (da) |
| BR (1) | BR6909697D0 (da) |
| ES (1) | ES368284A1 (da) |
| FI (1) | FI50551C (da) |
| FR (1) | FR2010827A6 (da) |
| NO (1) | NO126630B (da) |
| OA (1) | OA136E (da) |
| SE (1) | SE363138B (da) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3716447A (en) * | 1969-12-15 | 1973-02-13 | Dow Chemical Co | Delignification and bleaching of cellulose pulp with oxygen and alkali in the presence of magnesium chloride inhibitor |
| US4331507A (en) * | 1979-12-10 | 1982-05-25 | Dorr-Oliver Incorporated | Desilication in alkaline pulp processes |
| US4338158A (en) * | 1976-04-09 | 1982-07-06 | Weyerhaeuser Company | Pulping in the presence of a protector |
| US4486234A (en) * | 1981-03-20 | 1984-12-04 | Herr Alfons K | Fiber material |
| US5302248A (en) * | 1992-08-28 | 1994-04-12 | The United States Of America As Represented By The Secretary Of Agriculture | Delignification of wood pulp by vanadium-substituted polyoxometalates |
| US5549789A (en) * | 1992-08-28 | 1996-08-27 | The United States Of America As Represented By The Secretary Of Agriculture | Oxidation of lignin and polysaccharides mediated by polyoxometalate treatment of wood pulp |
| US20030024664A1 (en) * | 2001-02-27 | 2003-02-06 | Gibson Aileen Reyes | Eop & Ep process for bleaching of chemical pulp |
| US20080142175A1 (en) * | 2006-12-18 | 2008-06-19 | Caifang Yin | Process in a (D) stage bleaching of hardwood pulps in a presence of Mg (OH)2 |
| US20080142174A1 (en) * | 2006-12-18 | 2008-06-19 | Caifang Yin | Process in a (D) stage bleaching of softwood pulps in a presence of Mg (OH) 2 |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1887863A (en) * | 1929-11-15 | 1932-11-15 | Arthur D Little Ind Corp | Process for making pulp |
| US2169473A (en) * | 1935-02-08 | 1939-08-15 | Cellulose Res Corp | Method of producing cellulose pulp |
| US3382149A (en) * | 1964-10-29 | 1968-05-07 | Du Pont | Bleaching of hardwood sulfite pulp with hydrogen peroxide, including pretreatment with alkali |
| US3384533A (en) * | 1963-09-19 | 1968-05-21 | Air Liquide | Delignification and bleaching of chemical and semichemical cellulose pulps with oxygen and catalyst |
-
1969
- 1969-06-05 SE SE07955/69A patent/SE363138B/xx unknown
- 1969-06-11 US US832477A patent/US3657065A/en not_active Expired - Lifetime
- 1969-06-11 FI FI691739A patent/FI50551C/fi active
- 1969-06-12 ES ES368284A patent/ES368284A1/es not_active Expired
- 1969-06-12 FR FR6919523A patent/FR2010827A6/fr not_active Expired
- 1969-06-12 BR BR209697/69A patent/BR6909697D0/pt unknown
- 1969-06-12 OA OA53633A patent/OA136E/xx unknown
- 1969-06-12 NO NO02429/69A patent/NO126630B/no unknown
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1887863A (en) * | 1929-11-15 | 1932-11-15 | Arthur D Little Ind Corp | Process for making pulp |
| US2169473A (en) * | 1935-02-08 | 1939-08-15 | Cellulose Res Corp | Method of producing cellulose pulp |
| US3384533A (en) * | 1963-09-19 | 1968-05-21 | Air Liquide | Delignification and bleaching of chemical and semichemical cellulose pulps with oxygen and catalyst |
| US3382149A (en) * | 1964-10-29 | 1968-05-07 | Du Pont | Bleaching of hardwood sulfite pulp with hydrogen peroxide, including pretreatment with alkali |
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3716447A (en) * | 1969-12-15 | 1973-02-13 | Dow Chemical Co | Delignification and bleaching of cellulose pulp with oxygen and alkali in the presence of magnesium chloride inhibitor |
| US4338158A (en) * | 1976-04-09 | 1982-07-06 | Weyerhaeuser Company | Pulping in the presence of a protector |
| US4331507A (en) * | 1979-12-10 | 1982-05-25 | Dorr-Oliver Incorporated | Desilication in alkaline pulp processes |
| US4486234A (en) * | 1981-03-20 | 1984-12-04 | Herr Alfons K | Fiber material |
| US5552019A (en) * | 1992-08-28 | 1996-09-03 | The United States Of America As Represented By The Secretary Of Agriculture | Oxidative delignification of wood or wood pulp by transition metal-substituted polyoxometalates |
| US5549789A (en) * | 1992-08-28 | 1996-08-27 | The United States Of America As Represented By The Secretary Of Agriculture | Oxidation of lignin and polysaccharides mediated by polyoxometalate treatment of wood pulp |
| US5302248A (en) * | 1992-08-28 | 1994-04-12 | The United States Of America As Represented By The Secretary Of Agriculture | Delignification of wood pulp by vanadium-substituted polyoxometalates |
| US5695606A (en) * | 1992-08-28 | 1997-12-09 | The United States Of America As Represented By The Secretary Of Agriculture | Oxidative delignification of wood or wood pulp by transition metal-substituted polyoxometalates |
| US5695605A (en) * | 1992-08-28 | 1997-12-09 | The United States Of America As Represented By The Secretary Of Agriculture | Oxidative delignification of wood or wood pulp by transition metal-substituted polyoxometalates |
| US5824189A (en) * | 1992-08-28 | 1998-10-20 | The United States Of America As Represented By The Secretary Of Agriculture | Oxidative delignification of wood pulp or fibers using transition metal-substituted polyoxometalates |
| US20030024664A1 (en) * | 2001-02-27 | 2003-02-06 | Gibson Aileen Reyes | Eop & Ep process for bleaching of chemical pulp |
| US20080142175A1 (en) * | 2006-12-18 | 2008-06-19 | Caifang Yin | Process in a (D) stage bleaching of hardwood pulps in a presence of Mg (OH)2 |
| US20080142174A1 (en) * | 2006-12-18 | 2008-06-19 | Caifang Yin | Process in a (D) stage bleaching of softwood pulps in a presence of Mg (OH) 2 |
| US7976677B2 (en) | 2006-12-18 | 2011-07-12 | International Paper Company | Process of bleaching hardwood pulps in a D1 or D2 stage in a presence of a weak base |
| US7976676B2 (en) | 2006-12-18 | 2011-07-12 | International Paper Company | Process of bleaching softwood pulps in a D1 or D2 stage in a presence of a weak base |
Also Published As
| Publication number | Publication date |
|---|---|
| FI50551B (da) | 1975-12-31 |
| SE363138B (da) | 1974-01-07 |
| OA136E (da) | 1970-12-15 |
| ES368284A1 (es) | 1971-07-16 |
| FR2010827A6 (da) | 1970-02-20 |
| NO126630B (da) | 1973-03-05 |
| BR6909697D0 (pt) | 1973-05-03 |
| FI50551C (fi) | 1976-04-12 |
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