CN1209480A

CN1209480A - Method for using ozone in bleaching of ECF

Info

Publication number: CN1209480A
Application number: CN98118627A
Authority: CN
Inventors: J·L·克罗德特; A·C·H·德布利托; E·萨尔瓦多尔; M·R·达斯尔瓦
Original assignee: Praxair Technology Inc
Current assignee: Praxair Technology Inc
Priority date: 1997-08-25
Filing date: 1998-08-21
Publication date: 1999-03-03
Also published as: ID23571A; EP0905307A1; BR9803217A; CA2245535A1; KR19990023814A

Abstract

A ECF bleaching method for bleaching lignocellulosic materials comprising a bleaching sequence of at least three sequential stages, said stages including an oxidative treatment stage, an alkaline extraction stage, and an acidification bleaching treatment stage using ozone.

Description

In the ECF bleaching, use the method for ozone

The present invention relates to a kind of method of from wood pulp, removing lignin, more particularly, relate to a kind of method of using the ozone bleaching ligno-cellulosic materials.

Since there is a spot of lignin, therefore, all darker by most paper pulp colors that the wood pulp pulp-making method obtains.In order to produce the paper of high brightness, must in bleaching process, remove these residual lignins fully.Up to this point, mol-chloric, clorox and chlorine dioxide also are the main bleaching preparations that uses in the cellulose pulp bleaching always, and described bleaching schedule for example has: C/DEDED, CEHDED, CEHD, CEHDH and CEHED.Pulp quality and bleaching cost are to determine the principal element of the bleaching schedule that uses.Yet along with found organic chloride in bleaching effluent, paper pulp and paper maker's industryization have been taken huge effort in recent years, to seek to reduce the new technology of discharging these materials in the waste water.

Reported already that the main source of waste water was: the bleaching process of the cellulose pulp of the reaction by mol-chloric and lignin degradation product." PCDDs that forms in the association with pulp bleaching and PCDFs " (Canadian paper pulp and papermaking, 1989.8) referring to people such as C.Rapppe.

Because chloride is made up of the carbon-to-carbon covalent bond, so they are difficult to natural degradation.In these materials, now prove, 2,3,7,8-tetrachloro dibenzofurans (TCDF) and 2,3,7,8-tetrachloro dibenzo two oxines (TCDD) be biological accumulation and have genotoxic potential and be disadvantageous to environment.

Owing to find the pressure of these materials in waste water, paper pulp and paper maker's industry are being researched and developed the bleaching technology of quality in the limit of present Environmental Law defined of the waste water that can produce excellent quality paper pulp, be produced simultaneously always.Therefore, pre-bleaching, bleaching and after bleaching technology have now been proposed.By adopting other preparation, for example chlorine dioxide, oxygen, hydrogen peroxide, ozone, enzyme and organic peracid reduce or eliminate the new bleaching technology of mol-chloric always in research and development.Use these preparations to form so-called ECF (element-free chlorine) bleaching schedule and TCF (totally chlorine free) bleaching schedule.

As if yet described these changes can't be satisfied the rules of relevant environment aspect government and the public's interests.Therefore, what press at present is to make the water circulation of employed process realization sealing in the pulping and paper-making.Use ECF and TCF program to give paper industry, that is, reclaim circulation, realized the water circulation of the sealing of bleacher by part or all of waste water is circulated to such chance.The cycling of this sealing is being measured in the sulfate pulp-making industry of some world scales, and purpose is to obtain rational cost, environmental quality and the acceptability of its product on market.

Up to now, make various effort and controlled this problem.Knew already that the after-treatment of using oxygen delignification and/or waste water was first kind of measure being taked after the illeffects of organic chloride on detecting aquatic organic matter.The oxygen delignification section can be removed about 40～50% residual lignin under the not obvious prerequisite that influences carbohydrate.Therefore, bleaching can be in low preparation consumption, and therefore carry out under a small amount of chlorination organic matter is drained into the situation of final waste water.

In the conventional bleaching program, an important improvement wherein is to reduce the consumption of using mol-chloric and increasing chlorine dioxide.In most pulp mills, the change of this operation is by carrying out at the first bleaching Duan Zhongyong chlorine dioxide substituted molecule chlorine.

Now report, by carry out oxygen delignification, by replacing chlorine with chlorine dioxide and, can reducing AOX (absorbable organohalogen compounds) amount in the waste water significantly by waste water is carried out a biological disposal upon.Also can reduce other important environmental pollution index in the waste water by these steps, as color, BOD and COD." chlorine dioxide replacement, oxygen delignification and biological treatment are to the effect of bleacher waste water " Tappi Journal (1993.7) referring to people such as J.W.Graves.

Ozone (three oxo-compounds) is a kind of strong oxidizer, and with lignin very strong reactivity is arranged.Ozone is used as the bleaching agent of the fibrous matter that comprises paper grade (stock) first, makes fiber stand the effect of the admixture of gas of chlorine dioxide and ozone.The ozone of sulfate pulp first decomposes under low and high-consistency and carries out, and observes that the solubility of ozone is the deciding factor of this method in fibrous suspension.Referring to people's such as M.Byrd " the ozone delignification and the bleaching of chemical pulp: review of literature ", Tappi Journal, 1992.3.

In ECF and TCF bleaching schedule, the use of relevant ozone is studied by the consumption that changes position, employed reaction density and the ozone of ozone stage in the bleaching schedule.For example, shown that ozone is used in the bleaching schedule.Be the oxygen section in alkaline medium before the ozone stage, and be thereafter simple alkaline extraction section, otherwise just be to use oxygen, use the extracting section of peroxide or oxygen and hydrogen peroxide.Finally bleach by chlorine dioxide (ECF program) section or hydrogen peroxide (TCF program) section.Referring to the WO91/18145 that invests people such as B.F.Gregg.

In addition, the US that invests Tsai relates to for 4,959, No. 124 with chlorine dioxide delignification (D), ozone bleaching (Z) and alkali extracting (E, Eo, Ep, Eo) step process softwood kraft pulp.

No matter the existing institute of prior art improves, but industrially still need a kind of running cost low, the waste water of generation low environment pollution obtains the better bleaching technology of final products similar or more excellent quality.

Therefore, one object of the present invention is by providing a kind of new bleaching technology with the ECF bleaching schedule of ozone, so that compare with the dioxde pulp bleaching process of routine, with regard to association with pulp bleaching to the similar brightness value, only need lower chemicals, especially ozone and the consumption of chlorine dioxide.

Another object of the present invention, be by providing a kind of new bleaching technology with the ECF bleaching schedule of ozone, when comparing with the dioxde pulp bleaching process of routine, the running cost of this bleaching technology is lower, generation is to the environment waste water of of low pollution more, and can obtain similar or the final products of excellent quality more.

The present invention relates to the ECF method for bleaching of a kind of bleached wood fiber material, this method comprises the step that has three orders at least, and described three steps comprise oxidation processes section, alkaline extraction section and use the acidifying bleaching processing section of ozone.

The oxidation processes section comprises that using the card uncle factor is chlorine dioxide treatment between 0.05 and 0.4, and its treatment conditions are: pH from about 2 to about 5, reaction density for from about 3% to about 15%, reaction temperature for being from about 10 minutes to about 180 minutes from about 20 ℃ to about 90 ℃, reaction time.

In one embodiment, alkaline extraction section comprise add alkali source and make reaction pH value rise to into about 10 or more, reaction time for from about 30 minutes to about 180 minutes, reaction density be from about 5% to about 15% and reaction temperature be from about 50 ℃ to about 120 ℃.

Alkaline extraction section comprises with oxygen to be handled, and wherein the consumption of oxygen is from about 0.2% to about 1.2%, and reaction pressure is from 100kpa to about 500kpa.Alkaline extraction section also comprises with peroxide to be handled, and wherein the consumption of peroxide is from about 0.2% to about 1.5%.Alkaline extraction section comprises that also additive capacity is from about 0.01% to about 0.2% magnesium.

Acidifying bleaching section is included in pH for from using the processing of inorganic acids for about 0 to about 5 times, the reaction density of this processing be from 1% to about 15%, reaction temperature for being from about 1 minute to about 60 minutes from about 20 ℃ to about 90 ℃, reaction time.In dry pulp, the dosage of ozone is from about 0.1% to about 1.0%.After this acidifying bleaching processing section is the alkali treatment section, and this section comprises that the interpolation alkali source rises to about 11.0 reaction pH value, and the reaction time is from about 5 minutes to about 90 minutes, and reaction temperature is from about 40 ℃ to about 90 ℃.After the acidifying bleaching processing section is the alkali treatment section.Can carry out the centre washing before the alkali treatment.

Acidifying bleaching processing section also comprises the interpolation chlorine dioxide, its consumption count from about 0.1% to 3.0% with dry pulp in case for from about 2 to about 5.5 final pH value, reaction density for from about 1% to about 15%, reaction time for from about 30 minutes to about 300 minutes, reaction temperature is to obtain desirable brightness during from about 30 ℃ to about 90 ℃.

In addition, also can add two independently chlorine dioxide stage.Washing section can be set between two chlorine dioxide stage.Alkaline extraction section can be arranged on independently between the second chlorine dioxide extracting section.In another embodiment, can add the chlorine dioxide stage that one or two hydrogen peroxide section replaces final one or two.In order to obtain desirable brightness for from about 9.0 to about 12.0 final pH value, the consumption of hydrogen peroxide with dry pulp count from about 0.5% to about 3.0%, reaction density for from 5% to about 25%, reaction time for from about 30 minutes to about 240 minutes, reaction temperature is from about 30 ℃ to about 120 ℃.The addition of magnesium counts from about 0.02% to about 0.2% with dry pulp.

In addition, the invention still further relates to the ECF method for bleaching of a kind of bleached wood fiber material, this method includes the bleaching schedule of a plurality of sequential steps, described sequential steps comprise the oxidation processes section,, alkaline extraction section and use the acidifying bleaching processing section of ozone.

Acidifying bleaching processing section is included in the paper pulp ozone decomposition step and adds ozone, reaction pH for from about 0 to about 5, reaction density with dry pulp count from about 0.1% to about 1.0%, reaction temperature for from about 20 ℃ to about 60 ℃.

In addition, the present invention relates to a kind of ECF method for bleaching that comprises bleached wood fiber's material of following bleaching schedule, this method for bleaching comprises: use oxygen that lignocellulosic material is carried out delignification to form the paper pulp of delignification; With the paper pulp of ClO 2 bleaching delignification to form bleached pulp; With alkali source bleached pulp is carried out extracting to form alkali extracting slurry; In acid medium, alkali extracting slurry is handled to form the paper pulp that ozone treatment is crossed with ozone; Handle with the paper pulp that alkali source is crossed ozone treatment; With the paper pulp crossed of bleaching ozone treatment.Another embodiment is to carry out the centre washing before the paper pulp of ozone treatment being crossed with alkali source is handled.

Other purpose, feature and advantage of the present invention will be conspicuous by following preferred embodiment explanation and accompanying drawing to those skilled in the art, in these accompanying drawings:

Fig. 1 is the bar chart that expression is shown in the variable of the bleaching efficiency of showing the distinct program in I, II and the III.Ratio between the total variable by brightness and the total electrical charge of oxidation preparation (chlorine dioxide, oxygen, ozone and hydrogen peroxide) obtains bleaching efficiency, and described bleaching efficiency is represented with " OXE " (oxidation equivalent);

Fig. 2 and Fig. 1 are similar, and its expression is shown in the bar chart of the variable of the bleaching efficiency of showing the distinct program in I and the II;

Fig. 3 is the bar chart that is shown in the bleaching efficiency variable of several bleaching schedules of showing the use the inventive method in III and the IV;

Fig. 4 is the flow chart of the bleaching schedule of a kind of embodiment of the present invention.

After carrying out oxidation with chlorine dioxide and carrying out extracting with alkali, by paper pulp being handled with ozone, after ozone treatment, with alkali paper pulp is carried out extracting once more, bleach till reaching desirable brightness with chlorine dioxide then and finished the present invention.

Different with the processing of before having carried out in this area, be chlorine dioxide treatment and alkali extraction steps before with ozone treatment in the present invention.Therefore, ozone neither with the reaction of the lignifying compound of the previous oxidation that is gone out by the alkali extracting, also not with the paper pulp reaction of high Kappa number.According to the present invention, ozone more selectively with the reaction of the paper pulp of low kappa number, this paper pulp contains the residual lignin of low free phenol structure.Described these structures shape the low selectivity of ozone bleaching, and the low phenol characteristic of paper pulp is because previous chlorine dioxide treatment is carried out the alkali extracting subsequently and caused.

The present invention shows, when carrying out ozone bleaching after carrying out oxidation with chlorine dioxide and carrying out extracting with alkali, this ozone bleaching is the most effective.In addition, the present invention also comprises the alkali extraction steps between chlorine dioxide stage and ozone stage.Therefore, ozone needn't react with the compound of chlorine dioxide degraded, and can more effectively react with the pre-bleaching paper pulp with low kappa number.

The present invention relates to the ECF method for bleaching of lignocellulosic material, described fibrous material is: needlebush, leaf wood, and composition thereof or the fiber of reuse.The method for bleaching that is proposed comprises many steps, has all changes in each step and between each step.The present invention allows to use the various cellulosic material that obtains by different pulping process.In addition, before method for bleaching of the present invention, cellulosic material can also optionally be handled with oxygen.

(can choose wantonly) first step comprises that with oxygen paper pulp being carried out delignification handles, and is intended to farthest reduce the content of residual lignin, and damages the degree of polymerization of cellulose chain not obviously.This processing can change over simple and conventional oxygen section uses two oxygen sections, also comprises and adds chelating agent and hydrogen peroxide.In order to understand this step better, illustrate in greater detail below:

-handle the oxygen delignification that (O) is routine, it is included in the alkaline medium and under low, medium or high concentration carries out the oxygen pressurized treatments to magma;

-processing (OO) is two sections oxygen delignification, and wherein, magma is carried out the pressurised oxygen processing in alkaline medium in two processing sections, not washing between two processing sections;

-processing OQ (OP) is two sections oxygen delignification, and wherein, magma is at first carried out pressurised oxygen with intermediate concentration and handled in alkaline medium.Then, paper pulp is washed, (for example EDTA and DTPA) handles with chelating agent, and washs once more.And then the second oxygen pressurized treatments section of employing in alkaline medium, in this section, also can use hydrogen peroxide.

Difference in these three oxygen delignification systems is bleaching efficiency and selectivity.Although its operation and installation cost of described last system for handling is the highest, it will obtain maximum bleaching efficiency and selectivity.In order to make the consumes least of preparation, the paper pulp of minimum as far as possible Kappa number is delivered to bleacher, and this is very important.

During the oxygen delignification step, for (OO) and OQ (OP) system, the reduction of Kappa number is between about 40-50%.

Second step of the inventive method is included under acid medium (pH＜4) and the middle concentration and with chlorine dioxide paper pulp is handled.The titanium dioxide chlorine dose that is used for the inventive method can be represented by the index that is called as the card uncle factor herein, this exponent specification the end Kappa number that floats slurry with described section in the relation of active chlorine percentage of use.For the present invention, this card uncle factor can change between 0.05 to 0.40, and for the kind of employed timber kind, paper pulp in the processing that obtains paper pulp, how and whether this factor will depend on the validity of carrying out oxygen delignification and chlorine dioxide.Industrial, this section is usually with symbol " D ₀" or " D ₁₀₀" represent.

This step also can be used the mixture of mol-chloric and chlorine dioxide, and this mixture is compared with independent use chlorine or chlorine dioxide, will be more efficiently for the delignified pulp lignin.These mixtures can use as follows: (DC), and (CD) and (C+D).

The brightness that reaches in this section is 60～75%ISO, and card uncle factor variations is respectively 0.10 to 0.24.Under the situation about changing at random of TCF program, first chlorine dioxide stage can replace by simple acidization or by a chelating section.

Third step comprises alkaline extraction section (E), is intended to dissolve the compound of chlorine dioxide stage oxidation.Now propose, the nucleophilic displacement of fluorine base that is produced by alkaline extraction section is essential, so that produce new electrophilic etch position in the lignin structure that stays.Referring to " delignification chemistry, universal: second portion ", J.Gierer, 1982.1, Holzforschung.This alkaline extraction section can carry out with oxygen (Eo), hydrogen peroxide (Ep) or their combination (Eop).The 4th kind of modification of alkali extracting is pressurized treatments, (PO), Pp or P _HT, wherein, use high temperature usually and for Eop, use more heavy dose of oxygen and peroxide.

In the 3rd step of the present invention, Kappa number is changed to 2.0～7.0, brightness is that 70～80%ISO, viscosity are 18～35cp.

The 4th step of the present invention comprises: in acid medium, under the condition that produces maximum Kappa number reduction and minimum carbohydrate degradation, paper pulp is carried out ozone treatment.In these conditions, a condition is that chlorine dioxide is used in combination with ozone, and wherein, therefore effect in the time of owing to two kinds of preparations may produce cooperative effect.Other condition of optimization effect is to use chelating agent to control the contacting efficiency of the distribution of metal (metal profile), control pH, pulp density, control ozone concentration and gas/paper pulp.Before ozone treatment, can in paper pulp, add chelating agent, oxalic acid for example, diethylene tetramine pentaacetic acid (DTPA) or diethylenetriamines tetraacethyl (DDTA) are included in tenor in the paper pulp with minimizing.

After handling with chelating agent, preferred pH regulator to 0～5 before using ozone with paper pulp.The concentration of wherein carrying out ozone stage can be high dense, in dense or low dense.Considered that before the ozone delignification stages paper pulp flocculate " is discongested " such fact, can provide sufficient gas/paper pulp contact surface because height is dense, therefore height is dense is favourable.Be considered to washing step for obtaining high dense dehydration/squeezing to paper pulp, wherein, the organic material of dissolving is capable of circulation between the recovery vehicle of pulp mill.

As the 4th step, the paper pulp that obtains after ozone stage can carry out or not carry out alkali extracting fast, with the compound of being degraded during dissolved lignin and the ozone reaction.The Kappa number of this paper pulp is lower than 4.0, brightness is that 80～86%ISO, viscosity are between 13～25cp.This alkali extracting effect can utilize oxygen (Eo), peroxide (Ep) or oxygen to add peroxide [Eop, (PO), Pp or P _HT] implement.

The 6th step and step in addition relate to the bleaching section of chlorine dioxide and/or hydrogen peroxide, so that reach the final brightness of 86～90%ISO and the viscosity of 12～25cp respectively.

Preferable methods of the present invention is shown among Fig. 4.Fig. 4 shows the bleaching schedule 10 of DEo (ZE) D.The paper pulp 20 that derives from back-oxygen wash engine is delivered to middle underflow pump 30, then before delivering to D-section 34 in chlorine dioxide 62 is delivered in the dense blender 32.Dense equipment during all pumps described herein and blender are.In wash engine 36 treated and the washing after, this paper pulp is mixed before stock pump 38 with NaOH (and/or hydrogen peroxide) 64, then, before Eo (or Eop) extracting section 42, in blender 40, mix with oxygen 66.After the washing, paper pulp is mixed with sulfuric acid 68, and deliver to pump 46 and blender 48 forward in wash engine 44, paper pulp is handled with ozone 70 in blender.The paper pulp that ozone treatment is crossed mixes with NaOH 72 then, and delivers to extracting section 52 through pump 50.Then, in wash engine 54, paper pulp is washed, and be pumped to blender 58, in blender 58, paper pulp is handled in D-section 60 with chlorine dioxide 74 once more through pump 56.Then, the bleached pulp that obtains is delivered in the final wash engine.

Embodiment 1～7

The paper pulp that uses in embodiment 1～7 obtains by ITC (isothermal boiling) method in the laboratory, and its Kappa number is 17.3, ISO brightness is 39.3%, viscosity is 78.2cp.The condition of Shi Yonging is as follows in these embodiments:

(OO)-and section:: oxygen delignification is to carry out 90 minutes in 95 ℃ in the reactor of 600kPa pressure.To be that to add to concentration be in 12% the paper pulp for the magnesium sulfate of 1.8% NaOH, 1.8% oxygen and 0.3% in the dry material consumption;

The Do-section: with chlorine dioxide and concentration is that 12% paper pulp mixes, and this section carried out in 70 ℃ water-bath 30 minutes in Polythene Bag;

Eo and Eop section: with concentration is that 12% paper pulp carries out 15 minutes alkali oxide extracting with oxygen in pressurized reactor under 200kPa pressure and 90 ℃, and carries out 75 minutes alkali oxide extracting under normal pressure.Add 0.5% magnesium sulfate, except as otherwise noted outside, employed hydrogen peroxide is 0.5%;

The Z-section: carry out in the paper pulp of ozone stage acidifying formerly, slurry concentration is 45%, room temperature, about 30 seconds of processing time.Under 6% slurry concentration and room temperature, to paper pulp sample acidifying 5 minutes, dehydration was concentrated into about 37% slurry concentration to usefulness 4N sulfuric acid then at pH2.5.Then this paper pulp is discongested, and will starch concentration once more and determine 40～45%.And then the paper pulp with 25 gram over dry equivalents carries out the ozone decomposition in the glass reactor of rotary evaporator is housed;

(ZD)-section; In this step, use the mode identical that paper pulp is handled with the Z-section, after this section immediately water and chlorine dioxide with the concentration dilution to 12% of paper pulp.This chlorine dioxide stage was carried out in 70 ℃ water-bath 30 minutes in Polythene Bag;

(ZE)-and section: after ozone decomposes, be about 11.0 times at pH immediately and handle with 70 ℃ sodium hydroxide solution, the reaction time is 30 minutes;

The D-section: under 70 ℃ and 12% concentration, carry out chlorine dioxide stage, the time is 180 minutes;

Washing: in the container that screen cloth is being arranged with excessive distilled water between each section or in Buchner filter, paper pulp is washed.Do not wash between the section at (OO), (ZD) with (ZE).

The contrast first of the inventive method and art methods is shown in the table 1.This has expressed following data: the saving amount (kilogram) and the bleaching efficiency of the chlorine dioxide of the final brightness of paper pulp and viscosity, the total consumption of chlorine dioxide, use per kilogram ozone.

In

assessment embodiment

1,2 and 3 o'clock,, therefore do not observe tangible chlorine dioxide and save owing in bleaching process, use ozone.Yet, utilizing method of the present invention, embodiment 4, and it is about 57% that the total flow of chlorine dioxide will descend, and promptly every use per kilogram ozone will be saved 1.95 kilograms of chlorine dioxide.The obvious minimizing of this chlorine dioxide consumption will play a part very favourable for the closed circulation of bleacher.In addition, the paper pulp through the inventive method bleaching has demonstrated very high final brightness and viscosity.On the other hand, the bleaching efficiency of the inventive method also is better than conventional method for bleaching.

As can be seen, for embodiment 2 and 3, it is useful increasing ozone (embodiment 5) or use hydrogen peroxide (embodiment 6 and 7) when the alkali extracting.These changes will make the chlorine consumption significantly reduce 42%, 20% and 47% respectively.Yet, when with program of the present invention, promptly DEo (ZE) D (embodiment 4) is when comparing, for obtaining identical brightness value, this program display goes out lower efficient and selectivity, and demonstrates less chlorine dioxide saving amount and lower final viscosity value.

When analyzing the bleaching efficiency value of art methods, proved already that when using more ozone (embodiment 2 compares with 5), this parameter can only produce by a small margin to be increased, and when the use hydrogen peroxide, will be disadvantageous (embodiment 2 compares with 6) this parameter.

Method of the present invention has demonstrated maximum bleaching efficiency (2.30%) in the Z-ECF program of being assessed, and this value is respectively than the bleaching efficiency high 26.4% and 16.8% of embodiment 5 and 7.In the present invention, increase bleaching efficiency, refer to the method for routine and compare, in order to obtain identical final brightness, method of the present invention has consumed oxidant still less.

The table I

Embodiment	Bleaching schedule	Employed chemical dose (kg/odt paper pulp)						Total ClO ₂, kg/odt	?ClO ₂The saving amount ²	Brightness, %ISO	Viscosity, cp	Bleaching efficiency ³,％
Embodiment	Bleaching schedule	Employed chemical dose (kg/odt paper pulp)						Total ClO ₂, kg/odt	?ClO ₂The saving amount ²	Brightness, %ISO	Viscosity, cp	Bleaching efficiency ³,％	1	(OO) ¹DEoDD	?D	????Eo		????D		?D	???1.37	???--	????90.1	?30.5	2.18
?ClO ₂	???NaOH	???O ₂	????ClO ₂		ClO ₂										?D	????Eo		????D		?D
?ClO ₂	???NaOH	???O ₂	????ClO ₂		ClO ₂	9.6	???5.2	????6	????3.0		?1.1
?2	(OO)ZEoDD	?Z	????Eo		????D		???5.2	????6	????3.0		?1.1	?D			???12.2	??0.38	????89.3	?17.2	1.75
		?Z	????Eo		????D		?O ₃	???NaOH	???O ₂	????ClO ₂		?D	ClO ₂
		?4	????8.8	????6	????4.6		?O ₃	???NaOH	???O ₂	????ClO ₂		?7.6	ClO ₂
		?4	????8.8	????6	????4.6		?3	(OO)(ZD)EoDD	(Z???????????D)		????Eo		????D	?D						???13.7	????0	????90.5	?21.4	1.72
?O ₃	????ClO ₂	???NaOH	????O ₂	???ClO ₂	ClO ₂				(Z???????????D)		????Eo		????D	?D
?O ₃	????ClO ₂	???NaOH	????O ₂	???ClO ₂	ClO ₂	?4			????6.1	????6.1	????6	????6.1	?7.6
?4	(OO)DEo(ZE)D	?D	????Eo		(Z?????????E)				????6.1	????6.1	????6	????6.1	?7.6	D	????5.9	??1.95	????90.4	?23.4	2.30
		?D	????Eo		(Z?????????E)		?ClO ₂	???NaOH	????O ₂	???O ₃	NaOH	?ClO ₂		D
		4.4	????5.2	????6	????4	????7.8	?ClO ₂	???NaOH	????O ₂	???O ₃	NaOH	?ClO ₂	?1.5
		4.4	????5.2	????6	????4	????7.8	?5	(OO)ZEoDD	?Z	????Eo		????D		?D						????8	?0.95	????89.7	?13.1	?1.82
?O ₃	???NaOH	???O ₂	????ClO ₂		ClO ₂				?Z	????Eo		????D		?D
?O ₃	???NaOH	???O ₂	????ClO ₂		ClO ₂	?6			????8.8	????6	????5.7		?2.3

?6	(OO)ZEopDD	?Z	?????????????Eop			??D	?D	????11	????0.68	????90	?15.1	????1.7l
		?Z	?????????????Eop			??D	?D						?O ₃	?NaOH	?O ₂	?H ₂O ₂	?ClO ₂	?ClO ₂
		?4	?12.9	?6	?3	?7.6	?3.4						?O ₃	?NaOH	?O ₂	?H ₂O ₂	?ClO ₂	?ClO ₂
		?4	?12.9	?6	?3	?7.6	?3.4						?7	(OO)(ZD)EopD	(Z??????????D)		?????????????Eop		?D	????7.2	????1.62	????90.2	?19.5	????1.97
?O ₃	?ClO ₂	?NaOH	?O ₂	?H ₂O ₂	?ClO ₂										(Z??????????D)		?????????????Eop		?D
?O ₃	?ClO ₂	?NaOH	?O ₂	?H ₂O ₂	?ClO ₂	?4	?6.1	?11.2	?6	?3	?1.1

¹Two sections oxygen delignification paper pulp: Kappa number 10.6, ISO brightness 51.6%, viscosity 44.8cp. ²Chlorine dioxide saving amount (kgClO ₂/ kgO ₃). ³Bleaching efficiency: by the ratio calculation between the oxidation equivalent (OXE) that consumes in the brightness gain in whole procedure and this program.

Embodiment 8～11

The paper pulp that uses in embodiment 8～11 obtains by ITC (isothermal boiling) method in the laboratory, and its Kappa number is 13.1, ISO brightness is 45.4%, viscosity is 52.5cp.The condition of using in the blanching step of these embodiment is identical with previous embodiment (embodiment 1～7), and different is to carry out pre-delignification stages with oxygen, below this section is introduced:

[OQ (OP)]-section: in reactor, carried out delignification 30 minutes with oxygen in 95 ℃.It is in 12% the paper pulp that NaOH with 1.6% and 0.3% magnesium sulfate are added into slurry concentration, and with oxygen the pressure of system is maintained 600kPa.After with oxygen delignification, up hill and dale paper pulp is washed with distilled water, then under 90 ℃ and 5% slurry concentration with 0.1% DTPA to pulp processing 5 minutes.With distilled water paper pulp is thoroughly washed again, and then in reactor, carry out new delignification when being treated to 60 minutes with oxygen in 95 ℃.It is in 12% the paper pulp that NaOH with 1%, 0.3% magnesium sulfate and 0.5% hydrogen peroxide are added into slurry concentration, and with oxygen the pressure of system is maintained 600kPa.

The table II has been described following data: the chlorine dioxide saving amount and the bleaching efficiency of total consumption, the inventive method and the conventional method of the final brightness of bleached pulp and viscosity, chlorine dioxide.Embodiment 11 clearly illustrates, compares higher bleaching efficiency with conventional method, consumes per kilogram ozone simultaneously and can save 1.20 kilograms of chlorine dioxide.On the contrary, provide 0.78 and 0.90 bleaching efficiency respectively in the conventional method shown in embodiment 9 and 10.By these embodiment as can be seen, for the handling procedure of routine, handling procedure of the present invention can produce similarly final brightness, but consumes still less ozone and/or chlorine dioxide, and can provide high final viscosity.

In embodiment 8～11, handling procedure of the present invention has demonstrated the highest bleaching efficiency in the Z-ECF program.It has increased about 8.5% than embodiment 10, program of the present invention, and promptly DEop (ZE) D is more efficiently when using oxidising agent.It must be noted that embodiment 8 is just with for referencial use, this is because this example is not used ozone.Need benly be, use method of the present invention, only consume chlorine dioxide seldom in whole process, for the closed circulation of bleacher, this be a very big advantage.

The table II

Embodiment	Bleaching schedule	Employed chemical dose (kg/odt paper pulp)							Total ClO ₂， kg/odt	?ClO ₂The saving amount ²	Brightness, %ISO	Viscosity, cp	Bleaching efficiency ³,％
Embodiment	Bleaching schedule	Employed chemical dose (kg/odt paper pulp)							Total ClO ₂， kg/odt	?ClO ₂The saving amount ²	Brightness, %ISO	Viscosity, cp	Bleaching efficiency ³,％	8	?OQ(Op) ¹DEopD	?D	????Eop					?D	????7.7	???--	?90.9	?22.4	1.41
?ClO ₂	???NaOH	????O ₂		????H ₂O ₂		?ClO ₂										?D	????Eop					?D
?ClO ₂	???NaOH	????O ₂		????H ₂O ₂		?ClO ₂	7.3	????10	????6		????3.0		?0.4
?9	?OQ(Op)ZEoPD	?Z	????Eop					????10	????6		????3.0		?0.4			?D	????3.8	????0.78	?90.2	?11.5	1.04
		?Z	????Eop					?O ₃	????NaOH	????O ₂		????H ₂O ₂		?ClO ₂		?D
		?5	????18.7	????6		????5		?O ₃	????NaOH	????O ₂		????H ₂O ₂		?ClO ₂	?3.8
		?5	????18.7	????6		????5		10	?OQ(Op)(ZD)EopD	(Z???????????D)		????Eop				?D						????4.1	????0.90	?90.2	?14.9	1.18
?O ₃	????ClO ₂	????NaOH		????O ₂	??H ₂O ₂	?ClO ₂				(Z???????????D)		????Eop				?D
?O ₃	????ClO ₂	????NaOH		????O ₂	??H ₂O ₂	?ClO ₂	?4			????3	????10		????6	????3	?1.1
11	?OQ(Op)DEop(ZE)D	?D	????Eop			(Z??????????D)				????3	????10		????6	????3	?1.1	??D	????4.1	???1.20	?90.3	?19.0	?1.28
		?D	????Eop			(Z??????????D)		?ClO ₂	???NaOH	???O ₂	H ₂O ₂	????O ₃	?NaOH	?ClO ₂		??D
		?3	????10	????6	??3	????3	????6	?ClO ₂	???NaOH	???O ₂	H ₂O ₂	????O ₃	?NaOH	?ClO ₂	?1.1

¹Two sections oxygen delignification paper pulp: Kappa number 80, ISO brightness 69.8%, viscosity 29.1cp. ²Chlorine dioxide saving amount (kg ClO ₂/ kgO ₃). ³Bleaching efficiency: by the ratio calculation between the oxidation equivalent (OXE) that consumes in the brightness gain in whole procedure and this program.

Embodiment 12～16

The paper pulp that uses in embodiment 12-16 is the paper pulp that obtains after the conventional delignification stages of carrying out with oxygen with commercial scale, Kappa number is 9.5, ISO brightness be 54.0% and viscosity be 26.5cp.Similar in condition of using in blanching step and the previous embodiment step, only difference is as follows in each section:

The D1-section: with chlorine dioxide and slurry concentration is that 10% paper pulp mixes, and this section carried out in 60 ℃ steam bath 30 minutes in Polythene Bag;

The Eop-section: with oxygen the paper pulp of 10% slurry concentration being carried out alkali oxide extracting, reaction time in the pressurized reactor of 95 ℃ and 200kPa is 90 minutes.Add 0.5% magnesium sulfate.

(ZD)-and section: in this step, use with mode identical described in " Z-section " paper pulp is handled, but will starch concentration dilution to 10%.Chlorine dioxide stage was carried out in 60 ℃ steam bath 30 minutes in Polythene Bag;

(DZ)-and section: use the acidifying described in the chlorine dioxide alternative terms " Z-section " at this, described chlorine dioxide carried out 30 minutes in 60 ℃ under about 2.5 to about 3.0 pH.Then paper pulp is dewatered, after this handle with ozone;

(ZE)-and section: the reaction time of this section is 15 minutes;

The D-section: this section carried out 180 minutes under 70 ℃ and 10% slurry concentration;

Washing: between every section and having in the case of screen cloth (120 order) or in Buchner filter, paper pulp is washed with excessive distilled water.(ZD), (DZ) and (ZE) section between do not wash.

The table III shows just to be handled industrial sulphuric acid salt-oxygen and floats when slurry program of the present invention and correction data of prior art program.These data show once more, and program Deop (ZE) D (embodiment 16) is more efficiently when using oxidising agent, and this can obtain rational bleaching efficiency, final brightness and viscosity.

Compare with referral procedure (embodiment 12), method of the present invention only need be lower than 59% chlorine dioxide and cause the oxygen consumption of per kilogram to save 1.40 kilograms chlorine dioxide.The consumption that conventional program (embodiment 13) has demonstrated lower bleaching efficiency, chlorine dioxide reduces about 37%.

The bleaching efficiency of program of the present invention also is better than (2.3%) and is considered to the embodiment 14 of effective procedure and 15 conventional program.

The table III

Embodiment	Bleaching schedule	Employed chemical dose (kg/odt paper pulp)								Total ClO ₂, kg/odt	?ClO ₂The saving amount ²	Brightness, %ISO	Viscosity, cp	Bleaching efficiency ³,％
Embodiment	Bleaching schedule	Employed chemical dose (kg/odt paper pulp)								Total ClO ₂, kg/odt	?ClO ₂The saving amount ²	Brightness, %ISO	Viscosity, cp	Bleaching efficiency ³,％	????12	?O ¹DEopDED	?D	??????????????Eop			??D		?E	?D	????12.1	?????--	?????89.8	?????15.6	?????1.84
??ClO ₂	????NaOH	????O ₂	??H ₂O ₂	??ClO ₂		?NaOH	?ClO ₂										?D	??????????????Eop			??D		?E	?D
??ClO ₂	????NaOH	????O ₂	??H ₂O ₂	??ClO ₂		?NaOH	?ClO ₂	??8.7	????12	????6	??5	??3		?3			?0.4
????13	????OZEopDED	????Z	???????????????Eop			??D		??8.7	????12	????6	??5	??3		?3			?0.4	?E	?D	?????7.6	?????0.90	?????90.1	?????12.0	?????1.62
		????Z	???????????????Eop			??D		????O ₃	????NaOH	????O ₂	??H ₂O ₂	??ClO ₂		?NaOH	?ClO ₂			?E	?D
		????5	????18	????6	??5	??5.7		????O ₃	????NaOH	????O ₂	??H ₂O ₂	??ClO ₂		?NaOH	?ClO ₂	?3	?1.9
		????5	????18	????6	??5	??5.7		????14	?O(ZD)EopDED	(Z????????????D)		??????????????Eop			????D	?3	?1.9	?E	?D						?????6.4	?????0.86	?????90.7	?????13.0	?????1.71
????O ₃	????ClO ₂	????NaOH	??O ₂	??H ₂O ₂	???ClO ₂	?NaOH	?ClO ₂			(Z????????????D)		??????????????Eop			????D			?E	?D
????O ₃	????ClO ₂	????NaOH	??O ₂	??H ₂O ₂	???ClO ₂	?NaOH	?ClO ₂			????5	????4.3	????12	??6	??5	???1.9	?3	?0.2
????15	?O(DZ)EopDED	(D????????????Z)		????Eop	??????D		???D			????5	????4.3	????12	??6	??5	???1.9	?3	?0.2	?E	?D	?????6.4	?????0.86	?????90.3	?????8.6	?????1.69
		(D????????????Z)		????Eop	??????D		???D	?ClO ₂	????O ₃	????NaOH	??O ₂	??H ₂O ₂	???ClO ₂	?NaOH	?ClO ₂			?E	?D
		??4.3	????5	????12	??6	??5	???1.9	?ClO ₂	????O ₃	????NaOH	??O ₂	??H ₂O ₂	???ClO ₂	?NaOH	?ClO ₂	?3	?0.2
		??4.3	????5	????12	??6	??5	???1.9	????16	?ODEop(ZE)D	??D	????????????????Eop			(Z???????????E)		?3	?0.2	??????D							?????5.1	?????1.40	?????89.8	?????12.7	?????1.75
?ClO ₂	????NaOH	????O ₂	??H ₂O ₂	??O ₃	???NaOH	????ClO ₂				??D	????????????????Eop			(Z???????????E)				??????D
?ClO ₂	????NaOH	????O ₂	??H ₂O ₂	??O ₃	???NaOH	????ClO ₂				?4.3	????12	????6	??5	??5	???6.5	????0.8

¹Two sections oxygen delignification paper pulp: Kappa number is 9.50, and ISO brightness is 54.0%, and viscosity is 26.5cp. ²Chlorine dioxide saving amount (kg ClO ₂/ kg O ₃). ³Bleaching efficiency: by the ratio calculation between the oxidation equivalent (OXE) that consumes in the brightness gain in whole procedure and this program.

Embodiment 17～23

The paper pulp that uses in embodiment 17～23 is to carry out the paper pulp that obtains after the conventional delignification stages with commercial scale with oxygen, and the Kappa number of paper pulp is 10.6 when the experiment beginning, ISO brightness is 45.8%, viscosity is 27.2cp.

Difference main in the step of these embodiment is to use peroxide (PO) bleaching of pressurizeing that the simple oxidation alkali extracting that provides with oxygen and peroxide is provided before the Z-section.It is to carry out under the oxygen pressure of slurry concentration, 600kPa 10% that the peroxide that utilizes pressurization is handled paper pulp, and treatment temperature is that 95 ℃, reaction time are 120 minutes.The various preparations that use in paper pulp are: 0.8% hydrogen peroxide, 0.5% O ₂, 1.6% NaOH and 0.5% magnesium sulfate.

The table IV demonstrates, and industrial sulphuric acid salt-oxygen floats the performance that slurry shows in the different Z-ECF programs.Be noted that ozone stage is in several positions of this program, two modification wherein of the present invention (embodiment 20～23) demonstrate maximum final brightness.When carrying out quick and simple alkali extracting, when and then just carrying out ozone stage (embodiment 21), improved the low viscosity that embodiment 20 is drawn.

Embodiment 22 and 23 contrast show, the pressurized peroxide section is the good substitute of the alkali extracting that provided by oxygen and hydrogen peroxide.These embodiment illustrate, and in order to obtain identical brightness and excellent slightly viscosity, it is effective reducing employed ozone amount.

Gone out maximum bleaching efficiency value by embodiment 21 and 22 illustrated program displaies of the present invention.Compare with the conventional program of embodiment 19, in embodiment 22, use ozone will cause efficient to increase by 22.9%.

The alkali extracting enhancing that demonstrates in embodiment 23 can reduce the bleaching efficiency of the inventive method.For this reason, when using high dose hydrogen peroxide and oxygen, will can not produce significantly effect to the consumption that reduces chlorine dioxide and ozone.

The table IV

Embodiment	Bleaching schedule	Employed chemical dose (kg/odt paper pulp)							Total ClO ₂, kg/odt	Brightness, %ISO	Viscosity, cp	Bleaching efficiency ³,％
Embodiment	Bleaching schedule	Employed chemical dose (kg/odt paper pulp)							Total ClO ₂, kg/odt	Brightness, %ISO	Viscosity, cp	Bleaching efficiency ³,％	????17	?O ¹ZEopD	?Z	??????????Eop			??????D			????10	?????85.5	?????12.8	?????1.79
?O ₃	???NaOH	O ₂	?H ₂O ₂	??????ClO ₂											?Z	??????????Eop			??????D
?O ₃	???NaOH	O ₂	?H ₂O ₂	??????ClO ₂			?5.9	???15	4	?4	??????10
????18	?OZEop(ZD)	?Z	??????????Eop			??????(Z???????????D)			4	?4	??????10				????10	?????79.7	?????13.9	?????1.59
		?Z	??????????Eop			??????(Z???????????D)			?O ₃	???NaOH	?O ₂	?H ₂O ₂	??????O ₃						?ClO ₂
		?3.1	???15	?4	?4	??????2.1		?10	?O ₃	???NaOH	?O ₂	?H ₂O ₂	??????O ₃						?ClO ₂
		?3.1	???15	?4	?4	??????2.1		?10	????19	?O(ZD)EopD	(Z??????????D)		???????????Eop						??????D		????14	?????86.6	?????13.8	?????1.79
?O ₃	???ClO ₂	?NaOH	?O ₂	?H ₂O ₂	??????ClO ₂						(Z??????????D)		???????????Eop						??????D
?O ₃	???ClO ₂	?NaOH	?O ₂	?H ₂O ₂	??????ClO ₂		?4	???4			?15	?4	?4	??????10
????20	?ODEopZD	?D	???????????Eop			??????Z		???4			?15	?4	?4	??????10		????D	????14	?????88.2	?????7.6	?????1.74
		?D	???????????Eop			??????Z		?ClO ₂	???NaOH	??O ₂	?H ₂O ₂	????ClO ₂		?ClO ₂		????D
		?4	???15	??4	?4	????5.3		?ClO ₂	???NaOH	??O ₂	?H ₂O ₂	????ClO ₂		?ClO ₂	????10
		?4	???15	??4	?4	????5.3		????21	?ODEop(ZE)D	?D	???????????Eop			(Z????????E)		????D					????14	?????89.9	?????11.5	?????1.81
?ClO ₂	???NaOH	??O ₂	?H ₂O ₂	?O ₃	?NaOH	?ClO ₂				?D	???????????Eop			(Z????????E)		????D
?ClO ₂	???NaOH	??O ₂	?H ₂O ₂	?O ₃	?NaOH	?ClO ₂	?4			???15	??4	?4	?5.3	?7.4	????10
????22	?ODEop(ZE)D	?D	???????????Eop			(Z????????E)				???15	??4	?4	?5.3	?7.4	????10	????D	????10	?????87.1	?????12.7	?????2.20
		?D	???????????Eop			(Z????????E)		?ClO ₂	???NaOH	??O ₂	?H ₂O ₂	?O ₃	?NaOH	?ClO ₂		????D
		?4	???15	??4	?4	?32	?7.4	?ClO ₂	???NaOH	??O ₂	?H ₂O ₂	?O ₃	?NaOH	?ClO ₂	????6

????23	?OD(PO)(ZE)D	?D	????????(PO)			(Z????????E)		?D	????10	?????87.1	?????13.9	?????1.71
		?D	????????(PO)			(Z????????E)		?D					?ClO ₂	?NaOH	?O ₂	?H ₂O ₂	?O ₃	?NaOH	?ClO ₂
		?4	?16	?8	?8	?1.6	?7.4	?6					?ClO ₂	?NaOH	?O ₂	?H ₂O ₂	?O ₃	?NaOH	?ClO ₂

¹Two sections oxygen delignification paper pulp: Kappa number 10.6, ISO brightness 45.8%, viscosity 27.2cp. ²Chlorine dioxide saving amount (kg ClO ₂/ kg O ₃). ³Bleaching efficiency: by the ratio calculation between the oxidation equivalent (OXE) that consumes in the brightness gain in whole procedure and this program.

According to the present invention,, therefore, only be for convenience's sake concrete feature of the present invention to be shown in one or more accompanying drawings because each feature can combine with other feature.Those of ordinary skill in the art will appreciate that other embodiment, and these embodiments will be included in the scope of claims.

Claims

1. ECF method for bleaching that comprises bleached wood fiber's cellulosic material of three sequential segments at least, described each section comprise oxidation processes section, alkaline extraction section and use the acidifying bleaching processing section of ozone.

2. according to the method for bleaching of claim 1, wherein said oxidation processes section is included in that the card uncle factor is 0.05～0.40, pH is that about 2～about 5, reaction density is that about 3%～15%, reaction temperature is that about 20 ℃～90 ℃, reaction time are to carry out chlorine dioxide treatment under about 10～about 180 minutes condition.

3. according to the method for bleaching of claim 1, wherein said alkaline extraction section comprises: add alkali source so that the pH of reaction increases to more than about pH10, reaction time is about 30 minutes～about 180 minutes, reaction density be about 5%～about 15%, reaction temperature is about 50 ℃～about 120 ℃.

4. according to the method for bleaching of claim 1, wherein said acidifying bleaching section comprises: use inorganic acid to handle under about pH value of 0～about 5, the reaction density of this processing be about 1%～about 15%, reaction temperature is about 20 ℃～about 90 ℃, the reaction time is about 1 minute～about 60 minutes.

5. according to the method for bleaching of claim 1, wherein said acidifying bleaching processing section comprises: add ozone in the ozone decomposition step of paper pulp, reaction pH value is about 0～about 5, reaction density is 1%～about 50%, in the ozone consumption of dry pulp be 0.1%～about 1.0%, reaction temperature is about 20 ℃～about 60 ℃.

6. according to the method for bleaching of claim 1, after the wherein said acidifying bleaching processing section is alkali treatment, described alkali treatment comprises: add alkali source so that reaction pH value increases to approximately more than 11.0, the reaction time is about 5 minutes～about 90 minutes, and reaction temperature is about 40 ℃～about 90 ℃.

7. according to the method for bleaching of claim 1, be the alkali treatment section after the wherein said acidifying bleaching processing section.

8. ECF method for bleaching bleaching schedule, bleached wood fiber's cellulosic material that comprises many sequential segments, described each section comprises: the acidifying bleaching processing section of oxidation processes section, alkaline extraction section and use ozone.

9. method for bleaching according to Claim 8, wherein said acidifying bleaching processing section comprises: add ozone in the ozone decomposition step of paper pulp, reaction pH value be about 0～about 5, in the reaction density of dry pulp be 1.0%～about 50%, reaction temperature is about 20 ℃～about 60 ℃.

One kind comprise bleaching schedule, to the method for bleaching that ligno-cellulosic materials carries out ECF bleaching, described method comprises:

A) using oxygen that described ligno-cellulosic materials is carried out delignification handles to form delignification paper pulp;

B) with chlorine dioxide described delignification paper pulp is bleached to form bleached pulp;

C) use alkali source that described bleached pulp is carried out extracting to form alkali extracting slurry;

D) in acid medium, described alkali extracting slurry is handled to form the paper pulp that ozone treatment is crossed with ozone;

E) paper pulp of described ozone treatment being crossed with alkali source is handled; With

F) bleach the paper pulp that described ozone treatment is crossed.