CN1043798C

CN1043798C - Environmentally improved process for bleaching lignocellnlosic materials

Info

Publication number: CN1043798C
Application number: CN91108650A
Authority: CN
Inventors: B·F·格里格斯; T·P·冈德克; M·A·皮库林; A·罗森
Original assignee: Union Camp Patent Holding Inc
Current assignee: Union Camp Patent Holding Inc
Priority date: 1990-05-17
Filing date: 1991-08-07
Publication date: 1999-06-23
Anticipated expiration: 2006-08-07
Also published as: WO1991018145A1; CA2063591A1; BR9007533A; ZA915969B; EP0483163A4; PT98487B; EP0483163A1; CA2063591C; SE9200107L; ES2073027T3; JP2825346B2; NO920217L; SE9200107D0; DE69019350D1; PT98487A; EP0483163B1; JPH05500243A; NO920217D0; ATE122421T1; AU638017B2

Abstract

The present invention relates to a woodiness removing and bleaching process for lignocellulose wood pulp. An element, chlorine, is not used in the process, and a K value of the wood pulp approximately reaches 10 or is less than 10 through partial delignification. Viscosity is approximately greater than 13 centipoise, the woodiness of a part of paper pulp is removed in enough time through the ozone with effective quantity, so the obtained K value is approximately 5 or is less than 5, and the viscosity is approximately less than 10. On the basis of at least about 50 percent of GE brightness, the woodiness of the paper pulp is removed. The wood pulp of which the woodiness is basically removed is brightened by adding a bleaching agent, such as chlorine dioxide or peroxide to obtain a final product with at least about 65 percent of GE brightness. Filtrate can be recovered but is not discharged, so environment is improved.

Description

Improve the method for bleached wood fiber's material of environment

The present invention relates to a kind of new method that meets environmental requirement that is used for delignification and bleached wood fiber's paper pulp, wherein need not use the chlorine element and can produce the qualified paper pulp of intensity.The use of this method has also reduced the quantity of environmental pollution.

Timber comprises that the fiber of two kinds of Main Ingredients and Appearance-carbohydrate is cellulose part and non-fiber composition.The polymer chain of formation wood-cellulose part is arranged in parallel with each other and forms firm combining with the chain of vicinity.The non-pars fibrosa of timber comprises a kind of three dimensional polymeric material that is formed by the phenyl-propane unit basically, promptly said lignin.Though the major part of lignin also is to be distributed within the fiber itself, also some lignin forms a solid-state colony with it between cellulose fibre.

In order to use in paper technology, timber must at first be processed into paper pulp.So-called paper pulp is exactly a kind of xylon of suspended state, and placing them in and can forming a kind of thin layer on the screen cloth is paper.The method that pulping process adopted is usually directed to the physical or chemical treatment to timber, or these two kinds of methods are combined handles, so that change the chemical constitution of timber, makes final products have needed characteristic.The pulping technique that two kinds of main types are arranged, i.e. machinery pulping and chemical pulping.In machinery pulping, timber is broken down into filament by physics mode.In chemical pulping, wood chip chemical solution boiling, wherein a part of lignin is dissolved to be fallen so that with it eliminating.Normally used chemical pulping process roughly is divided into (1) soda processes, (2) sulphite process, and (3) sulfate process, the latter is adopted widely, and can carry out well-known various change, as the following stated.

Soda processes is known by the people in the present technique field, and it is that reactant pulverizes lignin so that it is got rid of with NaOH (NaOH).Sulphite process in this area also be known (for example can be with reference to " paper pulp and paper technology handbook ", the 6th chapter-sulphite slurrying, TAPPI, U.S.A.).

Sulfate process and many mutation thereof are a kind of basic chemical technologies that is used for paper industry.Basic sulfate process technology, as " paper pulp and paper technology handbook " the 7th chapter-sulfate process (TAPPI, U.S.A) described like that, relate to a kind of at NaOH (NaOH) and vulcanized sodium (Na ₂S) process of boiling wood chip in the aqueous solution.This method even also be extremely effective for the slurrying of the timber that as southern softwood, relatively is difficult to handle, identical for some other wood kind that is easy to slurrying, for example northern hardwood is the same with cork effective, sulfate process generally is used for the higher paper pulp of production intensity, because this method is to the destruction minimum of cellulose composition in the timber.

Improved sulfate process even can further reduce the destruction of pulping process to the cellulose fibre paradigmatic structure, thereby the loss of strength that makes final paper product more reduces than the sulfate process of standard, there is a kind of sulfate pulp-making technology of having improved to be known as " replenishing delignification handles " method, it is a broad concept in the art, various improved sulfate pulp-making technology have been comprised, for example in the operation of particular determination, or at the different parts of digesting apparatus, or at different time interval adding slurrying compounds, perhaps in the operation of appointment, cooling fluid is removed and refilled, so that more effectively remove more lignin, reduce the destructiveness of pulp liquor simultaneously to cellulose fibre.Another sulfate pulp-making technology of having improved is called sulfate-AQ technology, wherein a spot of anthraquinone is joined in the sulfate pulp-making soup and goes, so that accelerate delignificationization, reduces soup simultaneously to containing the destruction of wooden cellulose fibre.

There are various additional additional delignification treatment technologies in this area, comprising improving continuously cooking method (MCC) at the Kamyr described in TAPPI Vol.68 (11) .70 (1985) by V.A.Kortelainen and E.A.Backlund; Replace heating (RDH) by R.S.Grant fast at the Beloit that TAPPI Vol.66 (3) 120 (1983) is reported; And the Sunds Cold Blow cooking process of in " paper pulp and paper " Vol.59 (11) 90 (1985), being reported by B.Petterson and B.Ernerfeldt.

By sulfate process or improve the dark slurry that timber that kraft cooking crosses forms cellulose fibre, be referred to as " slightly starching ".The dark colour of thick slurry results from the following fact: be not that all lignin are removed in digestion process, and it chemical transformation in pulping process is become chromophoric group.Therefore want to make the color of thick slurry to shoal, promptly make it to be fit to printing, write and other paper demands of applications, must continue to remove remaining lignin by adding the delignification material, and remaining lignin conversion be become leuco-compounds by means of " bleaching " or " showing bright " processing.

Yet before paper pulp being floated certainly, the cooked material after all chemical treatments of pulping process finish generally is sent to one and independently goes in the spraying pot.In spraying pot, the pressure that is caused in the initial chemical treating process of ligno-cellulosic materials is disengaged, and paper pulp material is separated into fiber assembly.And then the fiber assembly that generates carried out a series of washing, so that remove all remaining chemical substances and solable matter (for example lignin), these materials have been separated from cellulosic material in pulping process.Often paper pulp is carried out the Screening Treatment of one or many,, they are carried out special treatment (boiling again, mechanical lapping etc.) again so that most not Fibrotic timber is separated.

The residue that comes from washing process is commonly referred to as black liquor, and they are collected, and concentrates, and with a kind of the very safe mode of surrounding environment is burned in recovery boiler then.The collection of black liquor, concentrate and combustion technology be in the art very common be well-known.

Delignification and bleaching process are to use selected chemical reactor that washed cellulose aggregate is undertaken by series of steps.In the prior art, adopted the chemical treatment mode of various combination.And each independent processing procedure can be rearranged with unlimited kind combination and replacement mode.Therefore, in order to make an explanation to various bleaching processes and system concisely, common combinations alphanumeric codes together replace the process in employed concrete chemical reactant and the processing procedure.

Now some alphanumeric codes that use for suitable afterwards place are done following introduction:

C: the reaction of chloridized-in acid medium, carry out with the chlorine element.

E: alkaline extraction-reactant is dissolved with NaOH.

E _o: alkali oxide extract-dissolves reactant with NaOH and oxygen.

D: chlorine dioxide treatment-in acid medium, use ClO ₂React.

P: peroxide treatment-in alkaline medium, react with peroxide.

O: oxygen treatments applied-in alkaline medium, react with oxygen element.

O _m: the paper pulp of the oxygen treatments applied of modification-first centering, low concentration carries out uniform alkali treatment, and the paper pulp to high concentration carries out oxygen treatments applied again.

Z: ozone treatment-react with ozone.

Z _m: improved ozone treatment-reaction uniformly takes place with ozone.

The mixture of C/D:-chlorine and chlorine dioxide.

H: the reaction that hypochlorite handle-carries out with hypochlorite in alkaline solution.

O _mAnd Z _mBe improvement technology of the present invention, the spy is described further in detailed description of the present invention.

Wood pulp is carried out delignification and bleaches to handle history has for many years been arranged with the chlorine element.The example that lignocellulose pulp is bleached is introduced in following document to some extent: the United States Patent (USP) 1 of authorizing people such as Campbell, 957,937, authorize people's such as Cranford United States Patent (USP) 2,975,169, authorize people's such as Kindron United States Patent (USP) 3,462,344, and the Chapter 11 of " paper pulp and paper technical manual ": bleaching (§ 11.3) (TAPPI, USA).

Yet, be a kind of effective bleaching agent although proved the chlorine element, but very difficult aspect control, and also it all has potential danger to the personnel and the equipment of factory.For example, come from the waste water of chlorine bleach process and contain a large amount of chlorides, they are by products of this technology.These chlorides are easy to cause corrosion to process equipment, thereby in the construction of factory, need to use expensive material, if do not adopt recovery system, the accumulation of chloride in machine will be carried out recirculation to the wash filtrate after the chloridized and bring obstacle in a closed system, need enlarge the place and recovery system is set, increase spends and process equipment is changed.In addition; for the potential impact of organic chloride in the waste water to environment; U.S. environment protection mechanism thinks that such material all is poisonous to humans and animals; thereby all there has been tangible change in government to the requirement of bleacher and permission; comprising some standards, and adopt traditional bleaching and pollution control technology can not reach these standards.

For fear of these shortcomings, paper industry is attempted employed chlorine element and chlorine-containing compound in minimizing or the cancellation lignocellulose pulp multistage bleaching technology always.Many use occasions of paper pulp all have very high requirement to the brightness of paper pulp, and this just makes these effort become more complicated.

For the problem of above-mentioned two aspects is combined, pay very big effort and developed a kind of bleaching process, make it not adopt chloride material, for example adopt oxygen to realize bleaching to paper pulp.The use of oxygen allows that the waste water that this technology produced is carried out recirculation and uses, and the use amount of chlorine element is significantly reduced.Proposed now manyly paper pulp to be bleached technology with delignification, for example United States Patent (USP) 1,860 of Richter with oxygen, 432, people's such as Grangaard United States Patent (USP) 2,926,114 and 3,024,158, people's such as Gaschke United States Patent (USP) 3,274,049, people's such as Meylan United States Patent (USP) 3,384,533, the United States Patent (USP) 3,251,730 of Watanabe, people's such as Rerolle United States Patent (USP) 3,423,282, the United States Patent (USP) 3,661,699 of Farley, the United States Patent (USP) 4,619,733 of Kooi and " sulfate pulp being bleached " (Norsk Skogindustri that P.Christensen writes with hydrogen peroxide, 268～271,1973).In the United States Patent (USP) 4,806,203 of Elton, propose to carry out carrying out alkali treatment earlier before the processing of oxygen delignification at paper pulp.

Adopt oxygen treatments applied then, the problem that is run into when using the chlorine element for solution is not a scheme that is entirely satisfactory.Oxygen is not to be a kind of delignification agent selectively as the chlorine element, uses traditional oxygen delignification method, and before cellulose fibre was subjected to flagrant destruction, the reduction of the Ka Bo value of paper pulp was very limited.And after the oxygen delignification is handled,,, only reduced the use amount of chlorine so far for to adopt the chlorine bleach method to remove residual lignin always in order to obtain the fully paper pulp of bleaching.Yet,, in closed-cycle operation, have corrosive chloride and also can reach a kind of concentration level that can not be accepted by the people very soon even adopt the chlorine of this low concentration.

For fear of adopting chlorine element bleaching agent, once the someone attempted to remove above-mentioned those remaining lignin with ozone in the bleaching of chemical sizwe, though initial ozone is to occur as a kind of ideal material that ligno-cellulosic materials is bleached, but its unusual oxidation susceptibility and expensive price have but limited its further developing in the technology of the ozone bleaching of ligno-cellulosic materials, especially for the processing of southern softwood.The reaction of ozone and lignin is very rapid, thereby the Ka Bo value is reduced, but in most of the cases, ozone also will damage the carbohydrate that contains cellulose fibre, and the intensity of finished product paper pulp is reduced greatly.Simultaneously, for example pH value is very responsive to processing conditions for ozone, and pH value directly influences its oxidisability and chemical stability, and the variation of this condition will influence the respond of ozone to ligno-cellulosic materials significantly.

Since beginning this century, when the delignification ability of ozone during, be suitable for the method that commercial scale is carried out to what lignocellulosic material was bleached in order to find a kind of ozone that adopts just by understanding, many people have done a large amount of constantly effort in this respect.And have a large amount of literal that relates to this field and patent to deliver, and some have occurred and carried out the research report of ozone bleaching in uncommercial experimental scale.For example, in people's such as Brabender the United States Patent (USP) 2,466,633, introduced a kind of method for bleaching, wherein made ozone (be transferred to drying) by a kind of humidity between 25～55%, pH value is 4～7 paper pulp.

S.Rothenberg, " with the oxygen bleaching of ozone " (Tappi, 182～185,1975)-Z of D.Robinson and D.Johnsonbaugh, ZEZ, ZP and Zpa (pa-Peracetic acid) to paper pulp; " using the bleaching to chemical sizwe of oxygen and ozone " (" Canadian paper pulp and paper magazine ", T153-58,1974)-OZEP of N.Soteland, OP and ZP have introduced some other bleaching process that does not adopt chlorine.

In the United States Patent (USP) 4,196,043 of Singh, introduced a kind of multistep bleaching, it also is to attempt not adopt chlorine-containing compound, and some examples of handling at hardwood are provided.Hardwood is bleached than most cork is easier, and this point is known for a person skilled in the art.The characteristics of this method are made up of 1-3 ozone bleaching step, handle with alkaline hydrogen peroxide at last, all insert an alkaline extraction process in each step.This operation is exactly ZEZEP with abbreviation letter representation commonly used in the paper industry.According to this method, the waste water that comes from each treatment step can be collected and be used to bleach the recirculation of operation, and preferably a treatment step to its front circulates.This patent also provides a kind of so-called waste water counter-current.

Though carried out so many research in this field, still there is not a kind of method to be adapted at producing paper pulp with the ozone bleaching wood fibre on the commercial size, especially to southern softwood, this mentions in the above, and the report of many failures is arranged.

The invention provides special slurry and bleaching handles in conjunction with the new method of carrying out, it has overcome the above-mentioned all difficulties that run in the prior art, in emission, do not have organic chloride substantially, and it is extremely low that colourity and bod are all reduced to, thereby can be suitable for industrialized mode and produce senior bleached pulp with a kind of.

An object of the present invention is under the prerequisite of not using chlorine element bleaching agent, to provide a kind of rapid method of multistep of lignocellulose pulp being carried out delignification and bleaching, thereby greatly reduce or eliminate environmental pollution, make the physical property of paper pulp reach best with a kind of method of energy and fund of using effectively.Method of the present invention can be handled all wood kinds, comprising the U.S.'s southern softwood that very is difficult to bleach.

Method of the present invention comprises three or more steps, among these steps or between some possible variations are arranged, these steps are described below:

First step relates to the technology of using any chemical pulping carries out delignificationization with wood chip and makes lignocellulose pulp, and next the organic matter and the boiling chemical substance of the most of stripping of flush away are carried out recirculation and recovery with it.Usually also comprise screening, so that get rid of the fiber block that those are not separated as yet in pulping process to paper pulp.This delignification is after the stage, the Ka Bo value (index is 21) in 20～24 scopes of U.S.'s south softwood pulp, cupri ethylene diamine (CED) viscosity number in 21～28 scopes the GE brightness value about 15～25, for U.S.'s southern hardwood, its Ka Bo value is about 10～14 (index is 12.5), and CED viscosity is about 21～28.

Be the part of effective embodiment of this first step below, but not only be confined to these:

A, use continuously or the method for boiling is in batches carried out sulfate pulp-making;

The method of b, employing alkali segmentation addition method and the final boiling of adverse current has the continuously cooking sulfate pulp-making of additional delignification;

C, employing soup be displacement and cold blow technology fast, the sulfate pulp-making with additional delignification that carries out boiling in batches; Perhaps

D, use continuously or in batches cooking process carry out sulfate-AQ slurrying to finish additional delignification.

Above-mentioned steps (b) and (c) in the additional delignification technology that adopted can comprise for example Kamyr MCC, Beloit RDH and Sunds Cold Blow boiling technology, these technology are described in the background technology part of this specification.According to employed lignin fibre type of material, can select the alkali that the front introduced and the technology of sulphite for use.

Second step of this method comprises an oxygen delignification processing procedure, do not cause the obvious decline of cellulose fibre intensity so that further remove delignification.This step will comprise that one is washed the process of removal with lysed organic matter and alkali, so that carry out recirculation and recovery.Certain time after the oxygen delignification is handled also can be carried out screening the pulp and be handled.

The processing stage of the oxygen delignification, the Ka Bo value of the paper pulp behind the enrichment be lowered 45% at least (handling) for O to 60% (for O _mHandle), and can not bring tangible destruction to the cellulosic cpd of paper pulp.And the ratio of the Ka Bo value of paper pulp and viscosity generally reduces by 25% at least.For above-mentioned soft wood pulp, use O _mHandle, be easy to make its Ka Bo value to reach 7～10, viscosity number is higher than 13.For hard wood pulp, after the oxidation delignification was handled, the Ka Bo value can reach about 5～8, and viscosity can be higher than 13.

Listed some embodiment that may adopt of this treatment step below, they are not construed as limiting this step:

A, traditional oxygen delignification are handled, it be included in low, in or in the paper pulp of high concentration paper pulp is carried out alkali and oxygen treatments applied (O); Perhaps

B, low paper pulp to middle concentration is carried out in the preferred embodiment of alkali treatment, pulp density is lower than 10% (weight), and then carries out the oxidation processes of high concentration paper pulp, this moment paper pulp concentration approximately greater than 20% (weight), i.e. O _mProcessing procedure.

Do not require that for those brightness value is higher than the paper pulp use occasion of 35%GEB (floating slurry in being often referred to as), can use, it can be sent into paper technology through the processing of step 2.

The 3rd step of this method comprises ozone gas bleaching processing (Z or the Z of an acidity _m), this processing procedure is carried out according to the technological parameter of one group of regulation, so that lignin is had the removal and the bleaching of high selectivity, makes cellulosic palliating degradation degree minimum simultaneously.These technologies are with reference to comprising the chelating agent that is used to control metal ion, the control of pH value, the control of pulp particles size, the control of pulp density, ozone concentration and gas/paper pulp contact condition.Before ozone treatment, can be with chelating agent, for example ethanedioic acid, diethylene-triamine pentaacetic acid (DTPA) or ethylenediamine tetra-acetic acid (EDTA) add in the paper pulp and go, so as to make it with paper pulp in metal ion form and combine.And the pH value of paper pulp is preferably in the scope that this third step carries out just being transferred to before about 1-4.This point can realize by the acidic materials that add q.s in paper pulp.Before the ozone delignification is handled, preferably make the concentration of paper pulp bring up to 35～45% (weight), the particle size of the bulk body of fiber can be crushed to 5mm or littler.This step also comprises the stage that the organic matter that dissolves is washed, so that it is carried out recirculation and recovery.

When ozone treatment, preferably the concentration with paper pulp remains on room temperature or is lower than 120 state, and ozone can be provided by the gas that contains ozone, and they can comprise for example oxygen or air.If the use ozone/oxygen mixture, between ozone concentration is preferably in 1～8% (volume ratio), if adopt ozone/air mixture, the concentration of ozone is about 1～4% and gets final product (volume ratio).In ozone reactor, should all pulp particles all be carried to the paper pulp that has removed lignin basically with the mode that ozone carries out even contact with a kind of.

Have been found that, after second treatment step, if the Ka Bo value of paper pulp is greater than 10, then be not suitable for carrying out the processing of the 3rd step, because, also need use a large amount of ozone for its Ka Bo value is reduced to predetermined level, thereby this will cause serious degraded that the character of paper pulp is brought adverse effect to the cellulose fibre of paper pulp, when the Ka Bo of paper pulp value is lower than 10, when ozone treatment, need only use more a spot of ozone, make the degree that degraded takes place cellulose be reduced to bottom line.No matter adopting the southern US cork for initial feed still is hardwood, through the product after the above-mentioned ozone treatment is that a kind of Ka Bo value is approximately less than 5, be generally the paper pulp of 3～4 (desired value is 3.5), its viscosity is greatly about more than 10, GE brightness is at least 50% (generally being about 54% or higher concerning cork, then is 63% or higher to hardwood).

Below effective embodiment of this step listed in, they were to the forecast scheme configuration restriction of this step:

A, the paper pulp after the acidifying is handled, making it to drive in the wrong direction with the ozone that with oxygen or air is carrier contacts; Or

B, the paper pulp after the acidifying is handled, make it be included in oxygen or air carrier in ozone forward move and contact.

Can also adopt various possible, approved bleachings and extracting method that paper pulp is added bleaching and handle, make paper pulp reach the state of abundant bleaching, promptly allow its GE brightness value reach about 70～95% level.Be its effective embodiment below, but do not constitute restriction this process:

A, after a subsidiary traditional extraction step that washing process arranged, and then carry out a subsidiary peroxide treatment (being the EP processing) that washing process is arranged;

B, after traditional alkaline extraction and washing step, and then carry out traditional chlorine dioxide treatment and wash (be ED handle);

C, after traditional alkaline extraction and washing process, and then carry out traditional chlorine dioxide treatment and washing, and then repeat to extract and chlorine dioxide treatment (being the ED-ED processing); Perhaps;

D, leaching process is strengthened, carried out traditional chlorine dioxide treatment, i.e. (E then with oxygen or oxygen and peroxide ₀) D or (E _0p) the D processing.

In a further embodiment, leaching process can also comprise makes the paper pulp that removes lignin basically combine with the alkali of q.s in the aqueous slkali, and its processing time and concentration depend on the consumption of the basic matterial that is used for dissolving all lignin that remain in the paper pulp.Then a part of aqueous slkali is extracted, so that remove all lignin of dissolving.

After the extraction stage, the paper pulp that removes lignin basically adds bleaching again and handles, and the processing GE brightness of paper pulp is later reached about 70% at least.Show bright dose and can preferentially select chlorine dioxide or peroxide etc. for use.

Adopt (E ₀) D, (E _0p) processing method of D or EDED embodiment, paper pulp can reach and compare higher brightness.Adopt ED embodiment, can not be used for recirculation and chemical substance is reclaimed if the filtrate after the chlorine dioxide treatment is not treated, because wherein contain butter.Because this is the unique filtrate that needs discharging from this technology, the amount of the volume of waste water and color, chemical oxygen consumption (COC) (COD), bod (BOD) and organic chloride has all greatly been reduced.Can make the pigment of water per ton be lower than 2 pounds, the BOD of water per ton.Be lower than 2 pounds, the total amount of organic chloride (TOCl) is lower than 2, is preferably lower than 0.8.Can also handle with the method for the membrane filtration filtrate after to chlorine dioxide treatment, it will satisfy the demand of whole recirculation basically.In EP embodiment, do not generate any chloride at bleaching stage, in fact all filtrate may be used to recirculation and recovery, forms a kind of technical process that produces waste water hardly.

Accompanying drawing 1 is the block flow diagram of the inventive method most preferred embodiment, and at this, solid line is represented the paper pulp flow process, and dotted line is represented the waste liquid flow process;

Accompanying drawing 2 is schematic diagrames of the preferred process of the present invention;

Accompanying drawing 3 is to be illustrated in ozone treatment apparatus among Fig. 2 along the part sectioned view of 3-3 line;

Accompanying drawing 3A is illustrated in preferred ozone treatment apparatus among Fig. 2 along the part sectioned view of 3-3 line;

Accompanying drawing 4 is the circulation fluid of various relatively different pulp processing technologies and the contrast figure of waste liquid.

The present invention relates to a kind of new-type side who paper pulp is carried out delignification and bleaching Method, it makes the suffered infringement of cellulose part in the timber be reduced to bottom line, because of And the pulp product that generates tool all for making paper and various paper product Gratifying strength character is arranged. For the ease of understanding the present invention owing to adopted at this The delignification that discloses and bleaching process and improvement that prior art is made, below right Several technological parameters in each different disposal stage in various delignification/bleaching process Describe.

A, summation

In this manual, adopt following definition mode:

What of amount of " denseness " representative paper pulp fiber in suspension slurry, its is with dry The gross weight of rear fiber and the percentage of moisture content recently represent. It is also referred to as pulp density sometimes Degree. The concentration of paper pulp depends on type and the operating condition of the dehydration equipment that adopts. Lower The definition of face take from Rydholm's " pulping process " (lnlerscience Publishcrs, 1965, P862～863) and TAPPl Monograph No.27 " bleaching of paper pulp " (Rapson, Ed, paper pulp and paper industry technological associations, 1963, P186～187).

" low concentration " comprises high to 6%, usually in 3～5% concentration range, and this paper Mass suspension can be carried with common centrifugal pump, and need not use pressure roller only Adopt decker and filter just can obtain.

" intermediate concentration " is between 6～20%. The 15%th, one in the mid-strength range Individual diacritical point, being lower than 15% concentration can obtain by filter. This concentration phase Pulp layer after in thick plasm scouring and bleaching system, leaving the vacuum filtration roller dense Degree. From the concentration of suspension slurry of thick plasm scouring machine or bleaching rinsing maching generally 9～15%. If concentration is higher than 15%, then need use pressure roller to dewater. Rydholm will The scope of intermediate concentration is decided to be 10～18%, and the concentration of Rapson appointment 9～15%. Although this suspended substance is a kind of liquid of viscosity under high temperature and certain pressure, Still can carry out pumping with special machine.

" high concentration " refer to concentration more than 20% until about 50%. Rydholm specifies Scope be that the scope of 25～35%, Rapson appointment is 20～35%, this concentration Slurry only have and use pressure roller to obtain. Liquid is wherein absorbed by fiber fully, Can only it be carried a very short distance with pump.

In addition, in this manual " slurrying " be used with its common implication, refer to The ligno-cellulosic materials boiling becomes thick slurry. Slurrying comprises sulfate system dress method, sulfate-The processing form of AQ pulp-making method and additional delignification.

Concept " improved sulfate pulp-making technology " this comprise replenish delignification process with And the every other improvement kraft process beyond removing sulfate-AQ method, because This technology has reached technically a special status and has been approved, therefore, Name to show difference with this mode. In addition, the oxygen delignification is processed after slurrying is finished To not be counted as and replenish the delignification processing, we are more prone to it is called paper pulp Bleach or phase I of aobvious bright delignificatino process.

Moreover, there is the method for two kinds of fundamental types to be used for determining slurrying or bleaching process Finish, i.e. " the delignification degree " of paper pulp and " aobvious brightness ". The delignification degree is generally used In pulping process and early stage bleaching stage. In paper pulp, only have this a small amount of quality to deposit The time, namely in the later stage of bleaching stage, this mode of measuring will lack accuracy. Brightness Generally combined use in bleaching process of factor only has slight face because work as paper pulp Look, and reflecting properties represents more accurate when very high with brightness.

The method that many measurement delignification degree are arranged, but wherein great majority are potassium permanganate The mutation of test method(s). Conventional potassium permanganate test method(s) provides a potassium permanganate Consumption or " Ka Bo value ", this numerical value be under certain conditions 1 the gram dry pulp institute The milliliter number of used up 0.1 equivalent potassium permanganate. The method is tried by the TAPPI standard Testing T-214 makes explicit provisions.

The method that also has the aobvious brightness of many test paper pulp. This parameter is normally to reflection A kind of mode of measuring of ability, its numerical value is represented with percentage. A kind of standard Method be exactly GE brightness, it represents with the percentage of maximum GE brightness, the party Method is determined by TAPPI standard method TPD-103.

In addition, in the detailed description that the present invention is done, on some ground that sees fit The side has adopted some alphanumeric codes to represent the various different steps of pulp processing, these Alphanumeric codes had been done introduction in the background technology part of this specification.

B, processing step of the present invention

The numerical value that the slurrying of the application of the invention, delignification and bleaching process have After (being Ka Bo value, viscosity and GE brightness) was listed in, these numerical value had reflected this Technical process is removed wooden in the paper pulp when reducing cellulose degradation as far as possible The size of plain ability. After the step with the oxygen delignification, aobvious bright step it Before, paper pulp is delignification partly, and its Ka Bo value is about 5 to 10, and is soft for the U.S. Wood is preferably 7 to 10, to U.S.'s hardwood then more preferably 5 to 7. This part The paper pulp of delignification, its viscosity is approximately higher than greatly 10, is higher than generally speaking 13, preferably extremely Be 14 less, (for soft wood pulp) or 15 (for hard wood pulp). This part delignification Material has good intensity and suitable viscosity, so it can support ozone resisting work With. The paper pulp of this partial dehydration element is further taken off lignin under the effect of ozone, make The Ka Bo value of soft wood pulp and hard wood pulp all is down to 3 to 4, and the GE brightness of paper pulp at least Reach about 50～70%. For soft wood pulp, typical GE brightness is about 54% Or higher, and concerning hard wood pulp, its numerical value is about 63% or higher. Connect Get off, add by the extraction effect of alkali and with chlorine dioxide or peroxide Bleaching process, the brightness of paper pulp further increases.

For the ease of the understanding of the present invention, accompanying drawing 1 has been listed with the form of general introduction and has been complied with Reach the various processing of adopting in the aobvious bright technology according to the present invention at slurrying, slurry delignification Step. As shown in Figure 1, the present invention includes a technical process that is formed by multi-step, It comprises the steps:

(a) lignocellulosic material is carried out slurrying, at this, being used for the chemical substance of slurrying can To adopt the method in the prior art to reclaim and re-use;

(b) filtering stock is removed chemical residue and remaining wood from the paper pulp soup Quality usually also comprises paper pulp is screened, in order to remove those in pulping process The fibre bundle of not yet separating;

(c) with oxygen and alkali paper pulp being carried out the delignification processing (is O or O_m)；

(d) the delignified paper pulp of part that above-mentioned steps C is obtained washs, with Remove the organic matter that dissolves in the oxygen treatments applied; Also can adopt the method for screening, also can With at least part of waste water in this step previous step is recycled;

(e) paper pulp is carried out chelating and acidifying, makes metal ion wherein obtain constraint, And its pH value is adjusted to a suitable level;

(f) paper pulp being contacted with ozone (is Z or Z_m), paper pulp is further taken off Lignin and part obtain bleaching;

(g) paper pulp of ozone treatment being crossed cleans, at least part of the giving up in this step Water can recycle use to previous step;

(h) carry out the alkali extracting in order to remove remaining lignin;

(i) paper pulp to extracting washs, and at least part of waste water can be to the previous step Suddenly recycle use;

(j) adding the second bleaching agent (is D or P, reaches in order to paper pulp is carried out blast Bleaching);

(k) detergent bleach paper pulp later reaches the GE brightness of the bleached pulp of gained To about 70～90%;

(l) with at least part of waste water in the P bleaching process step is the preceding advanced Row recirculation is perhaps drained the waste water that flows out in the D bleaching process, can certainly After it is suitably processed, be used for the recirculation in front step.

1, slurrying

First step of method of the present invention is slurrying, and the method that wherein adopts is carried The amount of the high lignin of getting rid of from the lignocellulose-containing material reduces again simultaneously The degree of cellulose degradation. The special slurrying worker who adopts in the method for the invention Skill is the type that depends on ligno-cellulosic materials to a great extent, more particularly, It is the type that depends on the timber that uses as parent material. As shown in Figure 1, be used for changing Paper pulp soup in the length of schooling sizing process can return with a kind of method of the prior art Receive and reuse. Typical situation be after this step followed by washing, Remove organic matter and the boiling compound of most of dissolving, in order to recycle and return Receive, also have a screening the pulp process, paper pulp passes sieve in this process, and those are in slurrying The fibre bundle of not yet separating in the process then is removed.

Compare with other technologies, sulfate pulp-making technology generally allows to use full wood material.The final slurry that is obtained with sulfate pulp-making technology has the acceptable physical property, though slightly the color of slurry is very dark.

According to the original material of lignocellulose, adopt the performance of the product that common sulfate process obtains to make it to be improved by the delignificatino process that replenishes or sulfate-AQ technology.More particularly, these technologies help reducing to the full extent the Ka Bo value of paper pulp, and the intensity and the viscometric properties of paper pulp are not brought any adverse influence.

When adopting sulfate-AQ technology, the amount of the anthraquinone in the cooking liquor approximately is at least 0.01%, and this weight ratio is that best situation is 0.02～0.1% for the oven-dry weight of the wood material used with respect to slurrying.The anthraquinone field trash helps the removal of lignin in sulfate pulp-making technology, and don't can bring any adverse influence to the cellulosic intensity property that is remained.And use the ancillary cost that anthraquinone brought to pass through subsequent step Z _m, the chemical substance of being saved among E and D or P cost and obtain the part compensation.

Also can adopt for example Kamyr MCC, Beloit RDH and Sunds ColdBlow method use the batch (-type) boiling vessel that the delignification that paper pulp replenishes is handled the replacement of using or additional sulfate-AQ technology.These technologies have the ability of removing more lignin when slurrying equally, and the cellulosic intensity property that is kept are not brought any adverse effect.

2, handle with the oxygen delignification

The part of the relevant bleaching process of next procedure of method of the present invention, it mainly is the remaining lignin in the thick slurry of processing in order to remove.In the method for the invention, this process comprises a step of carrying out the delignification processing with oxygen.The solid matter of being got rid of in this process is oxidized material, they are as black liquor, can be collected to concentrate then to adopt in common recovery boiler a kind ofly has the method for the Environmental security utilized to burn, at least the part of liquid substance can be carried out the recirculation use, as shown in Figure 1.

Have found that the process of carrying out delignification with oxygen can make the removal percentage of the remaining lignin in the thick slurry be improved, and viscosity that can corresponding reduction paper pulp.In general, a kind of approved already method is that the thick slurry that pulping process gets is handled under low concentration or intermediate concentration, to narrate as following, add a certain amount of alkali earlier, to guarantee needs with oxygen delignification process, and guarantee even distribution with alkali to increase its concentration then, under the high concentration condition, carry out the delignification processing.Though the high concentration delignification is handled and is construed to a kind of preferred technology, yet the technology of the usefulness oxygen delignification of low concentration or intermediate concentration also can be used for replacing it.

The high-concentration oxygen delignificatino process is preferably in a kind of aqueous solution of alkali and carries out, and pulp density is about 25%～35%, and preferably about 27%.Technology (the O that this has improved _m) can from thick slurry, remove at least 60% remaining lignin, and traditional oxygen delignificatino process is merely able to remove 45%～50%, has also avoided the reduction of paper pulp relative viscosity simultaneously.Use method of the present invention,, therefore, just constituted a kind of gratifying oxidation technology because this process of having improved has unique working ability.

This oxidation technology (the O that has improved _m) treatment step comprise that with wood pulp preferably the thick slurry of sulfate mixes equably with a kind of aqueous slkali, it is about below 10% to make the concentration of paper pulp remain on concentration expressed in percentage by weight, is preferably lower than 5%.The weight of the active alkali that is contained in the aqueous slkali should account for 0.5～4% of dry finish weight after the oven dry of thick slurry, and preferably about 2.5%.

This step is evenly distributed on alkali lye in the thick slurry of low concentration, and guarantees that all thick pulp fibres all is exposed in the equally distributed aqueous slkali.Surprising is to handle thick slurry with said method, substantial delignificationization does not take place in this processing procedure, but in ensuing high concentration oxidation delignification process, but than thick slurry more effectively having been removed lignin by the processing that aqueous slkali carried out under the high concentration situation with conventional method.Owing to avoided in the traditional high concentration paper pulp the existing alkali local inhomogeneities that distributes, thereby also just reduced the uneven phenomenon of consequent oxidation delignification.

This equally distributed stage preferably includes one makes paper pulp at least evenly combine 1 minute process with aqueous slkali, but preferably no more than 15 minutes.It is believed that if the processing time is less than 1 minute, can not provide an adequate time that slurries are evenly distributed, also can not produce further benefit if the processing time surpasses 15 minutes.

Furtherly, the paper pulp alkali treatment process of being carried out according to the present invention can be carried out in a very big temperature range, according to the result that practice draws, this processing procedure is preferably under the temperature conditions of room temperature to 150 carries out, and 90 °F～150 °F then is the optimum temperature interval.Reaction can be adopted normal pressure, also can carry out under pressurized conditions.Be evenly distributed in the paper pulp of aqueous slkali at low concentration, this processing procedure has also just been finished.The amount of aqueous slkali can great changes have taken place according to the concrete technological parameter of delignification reaction in the processing procedure.What of aqueous slkali are influential to the objective of the invention is, and it will depend primarily on the degree of delignification desired in the oxygen bleaching process and the concentration of used solution.The aqueous slkali that can preferentially select for use comprises that concentration is about the sodium hydroxide solution of 20～120g/l.This solution mixes mutually with the paper pulp of low concentration, and in the mixed liquid, the concentration of alkali is about 6.5～13.5g/l, preferably 9g/l.Under the condition of this alkali concn, when temperature is 120～150 °F, be after 3～5% the pulp processing 5～15 minutes to concentration, alkaline matter is evenly distributed in paper pulp.

According to most preferred embodiment of the present invention, when sodium hydrate aqueous solution being added in the paper pulp of low concentration, wherein the weight of NaOH should be 15% to 30% of dry pulp weight.Other alkali sources with corresponding sodium hydrate content also can be used, and for example come from the recovery of traditional sulfate pulp and the oxidation plain boiled water of regeneration cycle.

Through after the processing of above-mentioned low concentration hydroxide, the pulp density of handling is enhanced more than 20%, and preferably 25% to 35%, the whole bag of tricks well known in the art can be used for improving pulp density.

Thus, oxidation delignification process is just carried out in the paper pulp of high concentration, can adopt various known methods to make the oxygen of gaseous state be dissolved in the liquid-phase system of high concentration paper pulp, thereby realize delignification reaction.It is contemplated that all these known methods can be applicable to technology of the present invention.Yet the oxidation delignification process among the present invention is preferably introduced oxygen under the pressure condition of 80～100 pounds/in2 in the paper pulp liquid phase of high concentration and is gone, and the temperature of paper pulp is remained between 90 °～130 ℃.Average contact time between high concentration paper pulp and the oxygen was preferably between 20～60 minutes.

After preferred process technology of the present invention, can make oxygen delignification paper pulp Ka Bo value afterwards reduce at least 60%, and the cellulose composition in the paper pulp is not produced any destruction.Compare with traditional oxygen delignification, the latter's its Ka Bo value before cellulose is degraded can only reduce about 50%.Therefore, selection process of the present invention is come in and gone out and has been improved the delignification degree with expecting, compares with the delignificatino process of prior art, has increased by 20% at least, that is to say, make the reduction degree of the Ka Bo value of the paper pulp that enters bring up at least 60% by 50% of prior art.If keep the cellulose degradation of low limit, then the Ka Bo value can reduce by 70% even more.In the present invention, the cellulose composition wrecks in the paper pulp as long as just can avoid by the minor variations of observing pulp viscosity.

Just entering the oxygen delignification during stage, the Ka Bo value scope of different paper pulp is about 10～26, the type that the size of numerical value depends on timber (for example, sulfate pulp is about 10～14, the hardwood index is 12.5, then is about 20～24 concerning cork, and index is 21), and after the oxygen delignification was handled, its Ka Bo value was general in 5～10 scope.

Fig. 2 has drawn the technology sketch plan of carrying out method of the present invention with the form of general introduction.Each step of being drawn among the figure has been represented a desirable operating system, and it has embodied advantage of the present invention to greatest extent.Batten 2 is admitted to boiling vessel 4, carries out boiling in the soup in boiling vessel, for example boiling in NaOH soup and vulcanized sodium soup.Boiling vessel 4 produces thick slurry 8 of sulfate and black liquor 6, contains the product that molten Jie separates lignin in the black liquor.Thick slurry is handled in the washing unit, and the washing unit comprises spraying pot 10 and rinsing maching 12, and at this, remaining soup contained in the paper pulp is removed.Can adopt the whole bag of tricks in common knowledge in this area to wash thick slurry, for example leach washing, the rotation pressure washing, the level band filters, and dilution/extracting.All these methods are all within the protection domain of invention.In addition, in order to remove the not Fibrotic timber of the major part that exists in some technology, before or after washing class, also often thick slurry is sieved.

Thick slurry after the washing is admitted to processing unit 14, and paper pulp is handled with aqueous slkali and its concentration is remained on below 10% there, preferably below 5%.Technology of the present invention preferably includes a kind of device, with it the alkali lye of making 16 is sent into and is handled the place and keep desirable alkali content.The slurry of handling 18 is sent to dense volume unit 20, can adopt the method for squeezing there, make the concentration of paper pulp bring up at least 20% concentration expressed in percentage by weight, be preferably 25～35%, the liquid of removing from upgrading unit 20 22 preferably is transmitted back to washing unit 12, further uses.The thick slurry of " squeezing " of the high concentration that produces in upgrading unit 20 is sent to oxygen delignification reaction container 26 again, and they contact with oxygen 28 there.Thick slurry 30 after delignification is handled preferably is sent to the second washing unit 34 via spraying pot 32, washes slurry there with water, removes all lysed organic matters so that produce the paper pulp 36 of the low colourity of high-quality.At least a portion waste water that comes from this washing process is sent back to washing unit 12 and carries out reuse, waste water 13 from washing unit 12 can carry out recirculation separately, also can carry out recirculation jointly, their are introduced spraying pot 10 or finally send into black liquor line 6 with all or part of of waste water 38.In addition, the paper pulp of the part delignificationization after the oxygen delignification is handled can sieve, so that therefrom remove the fibre bundle of not separating as yet, it is for further processing, and for example carries out mechanical lapping.Paper pulp 36 can be from delivering to follow-up bleaching scene here, thereby produce the product of abundant bleaching.

Shown in Figure 2 is a splendid method of the present invention, in order successfully to use ozone bleaching, can produce sulfate pulp with timber, and the low concentration alkali processing/high-concentration oxygen delignification that has next improved is handled (O _m), as the above.Also once mentioned above,, be about 8～10 as its Ka Bo value of synthesis result of paper pulp for chopping wood, preferably 9, its viscosity should be greater than 13～14.Also can produce sulfate-AQ slurry with timber, carry out traditional oxygen delignification then and handle (be O, carry out high concentration alkali earlier and handle, carry out the high-concentration oxygen delignification again and handle), the paper pulp of gained has similar character.Do not adopt sulfate-AQ pulping process, can use additional delignificatino process yet, and then carry out the oxygen delignification processing of standard, so that make paper pulp have desired character.Also having a kind of method also is of great use, though because the increase of its cost or procedure of processing makes it can not constitute preferred plan.This method is with sulfate pulp-making and the delignification technology of replenishing, Kamyr MCC for example, Beloit RDH or SundsCold Blow Cooking technology combine, and these technology are described herein in the background technology part of this specification, and then carry out traditional oxygen delignification and handle.

Any slurrying and oxygen delignificatino process can be used in combination, as long as can make paper pulp reach above-mentioned Ka Bo value and viscosity number before ozone treatment.

In the present invention, generally do not adopt traditional sulfate pulp-making to add traditional oxygen delignificatino process, unless raw material is some hardwood, Populus wood for example, they are than being easier to delignification and bleaching, and plant for some other wood, adopt these traditional technologies in the ozone treatment process, often to need to use a large amount of ozone, the cellulose degradation that simultaneous is bigger.

When use is of the present invention, can reduce the consumption of ozone by using many replacement methods, these methods are included in the sulphate cook technology of standard and carry out improved oxygen delignification processing (O afterwards again _m), perhaps adopt improved sulfate pulp-making technology to handle (Kamyr MCC for example in conjunction with the delignification that replenishes again, Beloit RDH or SundCold Blow), and then carry out traditional oxygen delignification and handle (O), perhaps also can narrate, after sulfate-AQ digesting technoloy, carry out traditional oxygen delignification again and handle (O) as top.The delignification that replenishes after adopting improved sulfate pulp-making technology is handled, and (Kamyr MCC, Beloit RDH or SundsBlow), and then carry out improved oxygen delignification and handle (O _m), or employing sulfate-AQ digesting technoloy, handle (Kamyr MCC, Beloit RDH or Sunds Cold Blow) in conjunction with the delignification that replenishes and carry out traditional oxygen delignification again when handling (O), the consumption of ozone even may obtain bigger reduction.

In a kind of technology all these technology are used in combination, promptly improved sulfate-AQ digesting technoloy adds additional delignification processing (Kamyr MCC, Beloit RDH or Sunds Cold Blow), carries out improved oxygen delignification again and handles (O _m), even the consumption of ozone is even lower.The reduction of ozone-depleting amount can make the viscosity of paper pulp remain on the desirable level.

Adopt the above-mentioned high-concentration oxygen delignification bleaching that has improved to handle (O _m) advantage can by following method obtain the proof, promptly be that raw material is made comparisons the numerical value of its Ka Bo value and viscosity number and other processing mode gained under all identical situation of other treatment conditions with the southern softwood.Adopt the Ka Bo value of traditional sulfate pulp technology and traditional high-concentration oxygen delignification bleaching technology gained paper pulp generally to be about 12～14, viscosity is about 15.This Ka Bo value is too big for carrying out follow-up ozone delignification processing of the present invention, yet, when adopting traditional sulfate dress technology again when carrying out improved high-concentration oxygen bleaching process, obtained unexpected result, the Ka Bo value of its paper pulp is lower than 9, and pulp viscosity is higher than 12～14.The use that this good paper pulp Ka Bo value allows ozone delignification bleaching of the present invention to handle.

3, the ozone treatment stage

Second step of method of the present invention is that the thick slurry of handling through the oxygen delignification is carried out ozone delignification and bleaching processing.This ozonation treatment is carried out in an ozone reactor, for ozone reactor, will introduce in detail below, Fig. 2,3 and 3A in also be described.Before paper pulp is carried out ozone treatment, should regulate paper pulp earlier, obtain the most effective carrying out and make ozone reduce to bottom line to guarantee paper pulp selectivity delignificationization cellulosic chemical depletion.Paper pulp supplied materials 36 is admitted to blending bin 40, and paper pulp is diluted to a low concentration state there.With acid 42, for example sulfuric acid, formic acid, acetate or class acidoid add in the low concentration paper pulp and go, and make the pH value of the paper pulp in the blending bin 40 be reduced to 1～4 scope, preferably reduce between 2～3.Why will carry out above-mentioned pH value to paper pulp and regulate, be will depend on the PH size of pulp mixture because learnt the quality of paper pulp ozone bleaching effect.PH value is too low, can not bring any wholesome effect to the further processing of paper pulp, if pH value is higher than 4～5, then can cause the reduction of viscosity and the increase of ozone-depleting amount.

Handle with 44 pairs of acidated paper pulp of chelating agent, so that any metal or the metallic salt chelating that will be present in the paper pulp are lived.This chelation treatment should be able to make these metals lose activity in ozone reactor or become harmlessly, and like this, they just can not destroy ozone, the not reduction that can reduce the removal effect of lignin and cause cellulose viscosity.

Chelating agent is known, they comprise for example derivative of polycarboxylate and polycarboxylate, as binary, ternary or quaternary carboxylate, acid amides or analog, consider cost of material and action effect, for ozone treatment process of the present invention, relatively the chelating agent of Shi Heing comprises DTPA, EDTA and oxalic acid.The amount of chelating agent is about 0.1% to 0.2% o'clock of dry back paper pulp weight and can effectively if the concentration of metal ion is higher, then can adds more more chelating agents generally speaking.

The effect of ozone bleaching technology is subjected to the influence of many technological parameters that interrelate, and they comprise the content of metallic salt in the height of pH value and the paper pulp, and these were discussed in the above.Also has the concentration that very important parameter is a paper pulp in the ozone bleaching process.The paper pulp of being bleached must contain enough moisture content, and moisture content passes single fiber and formed a continuous phase, that is to say, fiber should be immersed in the water fully.The moisture content that is distributed among the fiber can be transported to the outer surface of fiber and approaching filamentary inside not too easily from its gas phase state with ozone, thereby lignin is fully removed from fiber, by water ozone is transported to fibrous inside and has crucial meaning.On the other hand, the concentration of paper pulp can not be too low, otherwise ozone has lost the discoloration to paper pulp with diluted and chemical breakdown.

For the cork of southern US, suitable concentration range about about 28%～50%, can obtain optimum efficiency greatly between 38%～45%.In above-mentioned concentration range, can obtain effect preferably, they show the delignificationization that has realized certain degree, cellulosic degradation amount is quite low, and handles brightness of pulp later and obviously improve.

The residing reaction temperature of ozone bleaching process equally also is an important governing factor for purposes of the invention.Ozone treatment, in temperature up to a certain critical-temperature the time: the reaction that is produced under this temperature conditions will begin to cause cellulosic excessive degradation.This critical-temperature will be according to being used for producing different types of timber of paper pulp and history that paper pulp is handled in earlier stage and tangible difference is arranged.When reacting, the maximum temperature of paper pulp should be no more than cause the cellulose excessive degradation temperature for the southern US cork, this maximum temperature is 120 °F～150 °F.

The ozone gas that is used for bleaching process can adopt the mixture of ozone and oxygen and/or a kind of inert gas, also can adopt ozone and AIR MIXTURES.

The amount that is dissolved in the ozone in the processing gas is subjected to the restriction of ozone stability in admixture of gas.Ozone gas mixture is for ozone/oxygen mixture, its ozone weight content generally is about 1～8%, for ozone/air mixture, the weight content of its ozone then is about 1～4%, and above-mentioned ozone gas mixture is suitable for the present invention.If the concentration of ozone in the raising ozone gas mixture can adopt more small-sized reactor, and for the paper pulp of equal number, the processing time can shorten.So just can reduce the investment quantity of equipment.Yet adopt the lower ozone mixture of ozone content but can reduce cost consumption, and can reduce operating cost.

Also having a governing factor is the relative weight of employed ozone when bleaching the paper pulp of given weight.This amount depends on that at least in part the amount of the lignin that need remove in the ozone bleaching process simultaneously will the balanced relative populations of considering cellulose degradation allowed in the ozone bleaching process.In preferred methods of the present invention, the amount of employed ozone should be able to react with about 50%～70% lignin in the paper pulp.In the ozone bleaching process, the whole lignin in the paper pulp all can not be removed, this point can still be about 3～4 from its Ka Bo value and obtain proof after process finishes.If during reaction whole lignin are removed, will cause between ozone and the cellulose overreaction taking place, thereby reduce the cellulosic degree of polymerization.In the reasonable method of the present invention, the amount of the ozone of adding is generally 0.2%～1% of oven dry paper pulp weight.Can make the level of lignin reach 3～4 Ka Bo values this moment.If there is a large amount of lysed solid matters in the system, then need to improve the consumption of ozone.

The reaction time of ozone bleaching is depended on the completion rate of ozone bleaching reaction, and the ozone that added this moment all or basically has been consumed.The length of this time is difference according to the difference of ozone mixture ozone concentration, and for the higher ozone mixture of concentration, reaction is carried out sooner, and the reaction time is also depended on the relative populations of the lignin that needs removal.Reaction time preferably is no more than 2 minutes.Certainly, according to other response parameter, this process also can proper extension.

The bleaching that an important feature of the present invention is a paper pulp is carried out very evenly, why can have these characteristics, some reasons are that paper pulp is crushed to the independently bulk particle with certain size, can guarantee that the diameter of pulp particles is enough little and have very low bulk density, ozone mixture will see through the major part of the bulk body of fiber fully like this, wherein also comprise fibrous mass.It is impossible wanting paper pulp fiber is separated into filament fully in crushing process.Pulverize the nuclear that bulk particle later has a denser in general, on every side around many outward extending fibers.In order to realize purpose of the present invention, need to determine the size of bulk particle, this be by measure determined already as yet not the diameter of the minimum of open centronucleus finish.

The uniformity of bleaching process also depends on some other technological parameter to a great extent, but have found that, if the size of bulk particle is limited at below the 5mm, even it is lower, for example preferably below the 3mm, then the great majority of these particles can obtain uniform treatment, and this point can obtain proof by observation, promptly can only see the center for the not good enough dark bulk body of the few bleaching degree of number.If the size of bulk particle is greater than 5mm, bleaching exists not good enough this fact of dark bulk body center of many bleaching degree and can be used as proof inhomogeneous.Therefore, it is crucial pulverizing fully, only in this way just can guarantee the mean value of most bulk body particle size less than 5mm, thereby makes ozone treatment realize homogenising.

Also having a prior technological parameter is should be able to make the particle that need bleach in the process of ozone bleaching by mixing, can both be exposed among the ozone bleaching mixture, so just can make all surface of ozone gas mixture, and make this mixture near all bulk bodies near bulk body.The even mixing of paper pulp in ozone gas mixture can obtain a gratifying effect, if bulk body is in a kind of state of quiescent bed, the bulk body of wherein some is compared with other, may be to be in a kind of state that is isolated with ozone gas, thereby make the bleaching degree of these bulk bodies be not so good as other.

The motion of bulk body makes it to be exposed in the mixture of ozone gas, makes all bulk bodies all obtain uniform treatment.This processing mode is removed a certain amount of lignin in the paper pulp equably, and makes the cellulose in all fibres that comprises bulk body that excessive damage not take place.According to the present invention the ozone treatment process is controlled, promptly adopt controlled particle size and in the ozone treatment process, realize turbulence, resulting in this case final slurry, its GE brightness, the excursion of Ka Bo value and viscosity number generally is no more than 5%.By contrast, if processing procedure is inhomogeneous, for example adopt quiescent bed reactor (promptly the particle in the reactor is not stirred in the ozone treatment process), some positions in the reaction bed are overbleaching, and other positions remain on the state that reacts relatively, and this is to flow through the quiescent bed reactor in uneven mode because of ozone gas mixture.

When the paper pulp of high concentration being handled,, certainly will cause fiber bleached inhomogeneities if the pulverizing situation and the filament of paper pulp fiber are not controlled meticulously with suitably contacting of reaction gas flow with ozone.Among the application this uneven ozone treatment is represented with letter " Z ".The improvement ozone bleaching technology that adopts according to the present invention, as the above, fiber wherein is crushed to 5mm even littler, and makes it to realize suitable contacting equably with streams of ozone, this treatment process letter " Z _m" expression.

The GE brightness of the paper pulp in ozone reactor is approximately at least 50%, and is generally about 50～70%, for hardwood, general big about more than 55%.The Ka Bo value of this paper pulp (no matter being hardwood or cork) is about 3～4 (index is 3.5), this hereto the paper pulp in the process segment be to be entirely satisfactory.

A kind of device that is particularly suitable for ozone bleaching technology of the present invention as Fig. 2,3 and 3A shown in.Mention above, the paper pulp 36 after the washing is sent to blending bin 40, handles with acid 42 and 44 pairs of paper pulp of chelating agent there.The low concentration paper pulp of handling through sour and chelating agent 46 is sent to upgrading unit 48 again, so that remove excess liquid 50 from paper pulp, upgrading unit can be a two roll press, and through extruding, the concentration of paper pulp is brought up to predetermined level.The unnecessary liquid 50 of at least a portion can be sent to and carries out reuse in the blending bin 40, and remainder is sent spraying pot 32.High concentration paper pulp 52 by 54 pairs of generations of screw feeder is carried, this feeding machine plays the effect of air seal to ozone gas, and then by reducing mechanism 56, aerator for example, paper pulp is ground into the bulk body 60 of the paper pulp fiber with preliminary dimension there, mention above, this size is about 5mm or smaller.Paper pulp after the pulverizing is sent in the dynamic ozone reactor 58 then, shown in accompanying drawing, this reactor is a conveyer 62 that is driven by motor 64, conveyer 62 is specifically designed to the mixing and the conveying of pulp particles 60, so that in the motion process of paper pulp, make wherein that all surfaces of particle can both be exposed among the ozone gaseous mixture 66, from Fig. 2, it can also be seen that, handle the bulk body 60 of paper pulp fiber later and be allowed to fall among the dilution bucket 68.

Fig. 3 is a drawing in side sectional elevation of ozone reactor 58, and it has reflected that pulp particles 60 is carried by conveyer 62 and distribution situation when passing reactor.Fig. 3 A is the drawing in side sectional elevation of a preferred conveyer, and the particle after it has adopted a kind of structure of paddle formula to pulverize sent reaction chamber 58.

Process shown in Figure 2 has shown the situation of paper pulp being handled with the ozone in the ozone gaseous mixture.Yet, change a kind of situation, can make in the paper pulp by bleaching to that part to greatest extent at first with ozone content the highest, initiate ozone mixture contacts, method is to send into along the gas that the direction opposite with the flow direction of paper pulp 60 will contain ozone.The paper pulp content of lignin that has just entered reactor is the highest, and at first contact is to be about to ozone mixture discharge, that almost run out of soon, and work can make whole ozone all be fully used like this.This also is the most effective a kind of method of desorb ozone from ozone/oxygen gas or ozone/air mixture.

As shown in Figure 2, if ozone 66 contacts with it in the mode that is parallel to paper pulp, used ozone 70 can reclaim use in dilution bucket 68.In bucket 68, dilution water 72 also is used as the sealing medium of ozone gas, and its adding has reduced the concentration of paper pulp, helps bleached pulp 74 and flows to next procedure of processing.

The residual ozone gas 70 that comes out from dilution bucket 68 is sent to and carries gas preliminary treatment place 76, carries gas 78 there, and promptly oxygen or air are added into wherein.Gaseous mixture 80 is admitted to ozone generator 82 again, produces the ozone gas that is fit to quantity there so that make it the concentration that reaches predetermined.Allocate suitable ozone/air Mixture 66 and be admitted to ozone reactor 58 again, so that paper pulp is carried out delignification and bleaching.

After the ozone bleaching process finishes, basically the paper pulp 74 that has removed lignin is thoroughly cleaned in rinsing maching 84 once more, as shown in Figure 2, recovery section in the rinsing maching 86 is sent to carries out recirculation and uses in the wash mill 34 of this technology, so just can be from the discharge rate of the minimizing waste liquid bigger environmental benefit of generation of starting with.

The content of bleaching low concentration paper pulp 74 later lignin after ozone treatment has reduced, and just the Ka Bo value is lower, and its viscosity also is suitable, and final Ka Bo value and viscosity number depend on the specific process that paper pulp experiences.For example, U.S.'s southern softwood is carried out slurrying, again with the high-concentration oxygen delignification method (O that has improved with traditional sulfate process _m) carry out preliminary delignification, then carry out once more delignification and handle with ozone, preferably adopt the sort of even ozone treatment method (Z that has improved _m), at this moment the Ka Bo value of slurry is generally 3～4, and viscosity number is about 10.If to U.S.'s south cork slurry, carry out improved high-concentration oxygen bleaching again and handle (O with sulfate AQ technology _m) and improved even ozone treatment (Z _m), the Ka Bo value of slurry generally is about 2, and viscosity number is generally greater than about 12%.

The paper pulp 74 that generates will have tangible brightness compared with the paper pulp of beginning.For example, southern softwood its GE brightness after pulping process is about 15～25%, and after the oxygen bleaching technology, GE brightness is about 25～45%, and after handling through ozone bleaching, its GE brightness is about 50%～70%.

4, alkaline extraction

Ozone treatment combines with the alkaline matter 90 of q.s and extracts after the paper pulp of washing clearly 88 is admitted in the extraction vessel 92.In container 92, paper pulp 88 is processed one section preset time under the effect of aqueous slkali, its treatment temperature also is predefined, and treatment conditions are relevant with the quantity of basic matterial, so just can go up all substantially and dissolves still remaining in any lignin in the paper pulp.The brightness that this leaching process has also improved paper pulp simultaneously generally can improve 2 GE brightness percentage points.Next, the paper pulp 94 after alkali treatment is sent in the rinsing maching 96, alkali lye is washed off from paper pulp, thereby all dissolved lignins are removed from paper pulp, has so just made a kind of paper pulp that is substantially free of lignin.This process is all known for those skilled in the art, needn't do further commentary.Embodiment narrates the extracting parameter that is fit in this technical process.At least a portion aqueous slkali 98 can be recovered, and they are sent to carries out recirculation in the rinsing maching 84.Can obtain environmental benefit preferably by the wastewater discharge that reduces this solution.

In some cases, when especially wishing to obtain than higher lightness, (E in the alkaline extraction process ₀), can the alkaline extraction effect be enhanced by the oxygen treatments applied that is accompanied by generation.This substitute mode is also known those skilled in the art, does not add detailed description at this.

5, additional blanching step

Concerning most paper products, final brightness is unsafty in 50～65% scope.If wish the GE brightness value is further brought up to 70～95% this higher levels, need paper pulp is shown bright bleaching, this processing mainly is that the chromophoric group that will remain in the lignin in the paper pulp converts colourless state to.

Paper pulp is being carried out alkaline extraction and again after the washing, can use the extraction that various materials cross ozone bleaching after paper pulp show bright bleaching.As shown in Figure 2, the paper pulp after the washing 100 combines with the bleaching agent of selecting 102 in bleaching container 104.Bleaching agent is preferably selected chlorine dioxide or peroxide for use.Paper pulp 106 after bleaching water 114 in rinsing maching 108 cleans once more, and the waste water after washing can be used as recirculation water 110 or makes waste water 112 and drain.If as recirculation, at least a portion washings 110 are admitted in the rinsing maching 96 and go.Paper pulp product through bleaching can be used for various occasion through collection.

Chlorine dioxide (D) (as Fig. 1) is a kind of base stock efficiently, has been used before this.In the present invention, use an amount of chlorine dioxide can make a kind of GE brightness value greater than 80% strong pulp.Have lower content of lignin owing to just entered the paper pulp of chlorine dioxide treatment stages, therefore show bright discoloration as long as use the chlorine dioxide that is equivalent to dry pulp weight about 0.25%～1% can finish it.

Be used for showing the chlorine dioxide of bright processing preferably through a processing procedure of removing monomer.Perhaps also can use the chlorine dioxide that only contains small amounts of monomer chlorine, since quite low through the content of lignin in the paper pulp of ozone bleaching, the increase that can not bring any undesirable pollutant.When the amount of employed chlorine dioxide is low unusually, can be emitted safely from the waste water in the last blanching step of the present invention, as shown in Figure 2.

If the waste water from last ClO 2 bleaching process does not conform with discharge standard, can use membrane filtration mode that waste water is further purified as counter-infiltration and so on.This technology can provide a kind of filtered fluid of cleaning, and the liquid after the filtration can return previous bleaching process and reuse, and work can reduce the use amount of fresh water like this.And the concentrated chlorine liquid behind membrane filtration is long-pending quite little.

Sometimes wish that paper pulp has high brightness value, for example reach 92～95%GEB, the bleaching that at this moment just need add is handled.Adopting additional extracting and chlorine dioxide treatment will be prevailing selection, so just produce a kind of O _mZ _mEDED bleaching order.

If do not use chlorine dioxide to carry out finally showing bright processing, also can show bright bleaching and handle with hydrogen peroxide, in Fig. 1, also shown bright.This technology provides a kind of not chloride fully bleaching circulation technology (O for example _mZ _mThe EP order), in bleaching process, do not form any chloride, do not need to use any numerous and diverse filtering technique the extraction product of liquid can be carried out repetitive cycling and use.Yet when adopting peroxide to use as bleaching agent, no matter be hardwood or softwood pulp, its Ka Bo value must be reduced to 6 level before entering the ozone treatment process, final products through peroxide treatment are had can received brightness, that is to say to make its GE brightness value be higher than 80% that this is because the discoloration of peroxide is strong unlike chlorine dioxide.A kind of if desired treatment process of not chloride/chlorine dioxide fully, peroxide can provide can received result.

Typical peroxide bleaches and using method thereof all are conventional in this process, and those skilled in the art knows working concentration, type and the method portion of this peroxidating agent, and hydrogen peroxide is the most suitable.

Through the paper pulp of washing and further apparent bright processing, its GE brightness value is preferably between 80～95% between 70～95%.And the physical property of this paper pulp can be complementary with the paper pulp that adopts traditional CEDED or OC/DED technology to obtain.

6, the recirculation of washes

In any pulping process, filtering control all is a significant effects factor for the economy cost of technological operation.The water that uses in the technology of the present invention is near the wastewater treatment before water source and the discharging specific requirement being arranged all.

In order to make great efforts to reduce the process water amount, always wish to allow waste water as much as possible carry out recirculation and use.When adopting the multistep treatment process of chlorine or chlorine dioxide, realize that this point is very difficult, this is that these chlorides are by products of above-mentioned chemicals because the waste water that this technology produces contains a large amount of chlorides.Like this, will cause muriatic accumulation, and then cause the corrosion of process equipment or must adopt expensive building structural materials if allow these waste water recirculation use.In addition, before these waste water discharge from factory, must carry out substance to the waste water of recirculation and handle, so just certainly will further increase the spending of equipment and treatment of pharmaceutical products.

As shown in Figure 4, no matter be to use traditional CEDED technology also to be to use OC/DED technology, consider that the waste water that produces in the washing process contains a large amount of chlorine-containing compounds, these technologies have all been brought the handling problem of waste water.Speak of above, these waste water can not be used as recirculation, and preferably it are handled before entering surrounding environment.The recirculation of waste water is used can reduce water consumption, but such work certainly will increase the rate of corrosion of process equipment, because the chloride content in the recirculation waste water can constantly increase.

By contrast, if adopt O of the present invention _mZ _mED technology only generates a spot of chloride in washings, these waste water can fall by safety dumping, promptly put into the gutter, and fully within the standard of environmental protection.These waste water also can become the thing that leaches that more cleans by reverse-osmosis treated, shown in figure, can be sent to it and go to carry out the recirculation use in the previous blanching step, and not have muriatic accumulation problem.If wish to adopt the D bleaching process, can adopt step to reduce the requirement of chlorine dioxide.Adopt E ₀Step can make paper pulp reach higher brightness, although improved owing to having used extra NaOH and oxygen to make it expense in this step.And have many known commercial runs can be used for preparing chlorine dioxide, make wherein remaining chlorinity reduce to minimum (R for example ₈Treatment process VS.R ₃Treatment process).For adopting the D step, the chemical substance of the chlorinity that these have reduced suits, and they can reduce muriatic content in the washes.

Also can use O of the present invention _mZ _mEP technology replaces O _mZ _mED technology can obtain the advantages that surmount prior art like this, at this moment generates without any chloride.All like this waste water all can be used for recirculation, the problem that does not exist any chloride to assemble in the technology washings.

Like this, technology of the present invention all has substantial advantage at the volume, color, COD, BOD and the organic chloride aspects that reduce waste water.And compare with the prior art that adopts chlorine, because muriatic content obviously reduces in the waste water after the washing, so the outlet of rinsing maching will no longer have machine chloride or gas, these materials must be handled before discharging.

In conjunction with following example scope of the present invention is further described, these examples are only used the purpose that lays down a definition, and never in any form scope of the present invention are construed as limiting.Unless otherwise, the percentage of all chemicals serves as to calculate the basis with the weight of over dry (OD) fiber, the people who is proficient in present technique will understand, it is very accurate that luminance index does not need to limit, and as the GEB value of paper pulp, plus-minus 2% all is qualified from its index, except that embodiment 11, a D step is all arranged in all examples, and a kind of R-3 type ClO 2 solution is used, and the ratio of dioxide and chlorine element is 6: 1 in this solution.Embodiment 1 (comparison)

With the torch pine wood chip by table I condition in the laboratory with the in addition boiling of amount of preparation, produce common sulfate pulp, the paper pulp of gained has K value 22.6, viscosity 27.1 centipoises.Then, sulfate pulp is handled (table II and table V) through conventional oxygen, then with common OC/DED program (table III) and OZ _mED bleaching schedule (table IV and table V) bleaching is to the demarcation brightness of last 83GEB, and ozone bleaching stage ozone with 0.61% in the liquid lime chloride of 35% concentration is bleached.

The table I

Torch pine sulfate pulp-making condition

Condition/step parameter

The pre-steaming time (branch) 2.5

To the 1 hour time of 175 ℃ of temperature

In the 1 hour time of 175 ℃ of temperature

Liquid: wood ratio 4: 1

Sulphidity (%) 25.8

Active alkali 17.4

Active alkali % 0.43 by the black liquor covering

Ka Bo value 22.6

Viscosity (centipoise) 27.1

The table II

The typical conventional O stage bleaching condition of pine

Pressure % chemical composition pH value temperature (℃) pulp density (gauge pressure pound/inch ²) %

80 2.5NaOH 10.2 110 27*

0.1MgSO ₄* to adding alkali and oxidation delignification

The table III

Pine typical C/DED conditions of bleaching

Step chemical composition PH temperature pulp density

(%) be worth (℃) (%)

C/D 3.6Cl ₂ 1.8 50 3.15

0.6ClO ₂

E 1.5NaOH 11.6 70 12

D 0.3ClO ₂ 4.2 60 12

The table IV

The typical acidization condition of pine step chemical composition PH temperature pulp density

The % value (℃) (℃) (H ₂SO ₄) acidization is to pH value 22 22 3-4 chelations (ethanedioic acid) 0.11 2 22 3-4

The table V

Pine typical case Z _mED conditions of bleaching step (%) chemical composition pH value temperature (℃) (%) pulp density Z (ozone) 0.2 to 12 to 4 22 35-45E 1.5NaOH 11.5 70 12D 1.0ClO ₂4.2 60 12

Shown in following table VI and table VII, under these conditions, at OZ _mThe paper pulp that ED bleaching is produced has and is equivalent to the intensive parameter of satisfaction of basic paper pulp that 83%GE demarcates the OC/DED of brightness, under these conditions, and OZ _mThe critical viscosity of ED paper pulp is 9.7 centipoises, uses 2.5%ClO in last D step ₂Occasion under, to OZ _mED paper pulp carries out intensive parameter and measures.Just reach demarcation brightness with excessive dioxy chlorine charging.OZ _mED paper pulp shows to have only and use the ozone that rolls up just can obtain higher brightness, and will cause the reduction of pulp viscosity and intensity like this to the chlorine dioxide treatment response characteristic.

The table VI

Pine sulfate pulp OC/DED and sulfate pulp OZ _mThe ED characterisitic parameter relatively

OC/DED OZ _mEDCSF ^*Tear coefficient breaking length CSF ^*Tear coefficient breaking length 646 205 6.54 659 228 5.85508 142 8.46 492 147 8.49351 145 8.81 334 126 8.50178 129 8.43 197 121 8.54* Canadian standard freeness

The table VII

Pine sulfate pulp OZ _mED luminosity response characteristics ClO ₂(%) 0 1.3 1.5 1.7 1.9 2.2 2.5 2.8 brightness 48.0 61.3 76.1 79.4 81.0 81.8 83.9 83.9 (GEB%) embodiment 2:

A kind of unbleached sulfate pulp/AQ slightly starches in the batch digester of laboratory by preparing in the torch pine fragment, as show as shown in the VIII, the Ka Bo value (K value) that gained does not float paper pulp is 18.3, viscosity is 20.6 centipoises, as indicated in the K value, content of lignin is significantly lower than embodiment 1 in the paper pulp that sulfate pulp/AQ slurrying condition produces, and as indicated in viscosity number, unacceptable degree is not also arrived in the reduction of pulp strength.

The table VIII

Torch pine sulfate pulp/AQ slurrying condition

Condition/step parameter

Give the steaming time (branch) 2.5

It to temperature 175 ℃ 1 hour time

It in temperature 175 ℃ 1 hour time

Liquid: wood ratio 4: 1

Sulphidity (%) 25.3

Active alkali (%) 18.0

Active alkali % 0.43 by the black liquor covering

AQ-% is in timber 0.025

K value 18.3

Viscosity 20.6 then, sulfate pulp/AQ does not float paper pulp via conventional OC/DED and the OZ shown in table II, III, IV and the V _mThe ED program, further bleaching and demarcating brightness is 83%GEB

The application of sulfate pulp AQ pulping technique has reached the target of producing the initial paper pulp of a kind of low K value, and it has satisfied viscosity characteristics for tool oxygen bleaching program.The ozone bleaching stage uses 0.35% ozone to carry out under 35% concentration, uses 1.6% C10 to reach demarcation brightness in the last D stage.

As shown in following chart IX and the X, in last chlorine dioxide stage, as measuring by luminosity response characteristics, optical property is modified, and to compare intensity property with the OC/DED starting point be satisfied.

The table IX

Pine sulfate pulp/AQOC/DED and OZ _mED character relatively

OC/DED OZ _mEDCSF tears coefficient breaking length CSF and tears coefficient breaking length 658 194 6.02 650 194 6.29524 139 8.1 4,497 159 7.83352 128 8.92 334 130 8.34190 119 8.74 211 121 8.59

The table X

Pine sulfate pulp/AQOZ _mED luminosity response characteristics ClO ₂(%) 0 0.8 1.2 1.6 2.0 2.4 brightness (GEB%), 52.9 76.8 80.7 83.2 83.4 83.8 embodiment 3 (comparison)

A kind of unbleached pine sulfate pulp K value about 24 is pressed into the weight concentration of about 30-36%, to make a kind of surface layer of high compact.The surface layer that does not float paper pulp is sprayed by 10% sodium hydroxide solution with capacity, produce a kind of paper pulp dry weight basis of pressing and roughly weigh percent 2.5 NaOH, the water of adding q.s does not float the paper pulp surface layer with adjustment and becomes 27% concentration, high concentration is not bleached surface layer and is re-used following condition: 110 ℃, 30 minutes, 80 pounds/inch of gauge pressures ²Carry out the oxygen delignification.Embodiment 4

The pine sulfate pulp of not bleaching of embodiment 3 is added in the container handling with 10% NaOH of enough volumes, with 30% the NaOH effect that is added in that dry paper is loaded onto in the stove, after the dilution water of q.s is added, in container handling, can obtain the unbleached pulp of a kind of weight concentration about 3%, in room temperature, stirred about 15 minutes with ribbon mixer, the unbleached pulp of handling is pressed into weight concentration about 27%.After concentrating, the NaOH on fiber approximates 2.5%, as embodiment 3.The unbleached pulp of handling carries out delignification by embodiment 3 described oxidation delignification technologies.The comparison sheet of the two is shown in the table XI.

The table XI

Comparison with example 3 and the 4 paper pulp oxidation stage discolorations of producing

Example 3 (O) example 4 (O _m)

K value 13 9

Viscosity (centipoise) 14.8 14.0

Adopt the adding low concentration alkali as the present invention who is seen in embodiment 3 and 4, handle (O with high concentration oxygen subsequently _m) to produce a kind of be the bleached brown paper pulp of big (hanging down the K value) than prior art delignification, it compared with prior art intensity without any substantial variation.

As the low K value paper pulp of producing with this process, each follow-up blanching step can be adjusted suitable higher brightness, the paper pulp of low content of lignin, therefore, its bleaching process of this paper pulp compared with the paper pulp of handling not according to the present invention needs less bleaching agent or short bleaching time.Embodiment 5

As according to the embodiment of the invention 4 described special oxidizing process (O that make paper pulp from pine _m) with common production process (O), (promptly without the low concentration alkali treatment step) compares, the average corrosion dosage of having found to be used for the high concentration oxidation delignification of unbleached pulp is 45 pounds of dry tons of every stoves (pound/ton) or 2.3%.On this level, the K value is on average reducing by 10 units by oxidation delignification reactor aspect the K value, press treatment step preferably, the same corrosive agent level that is used for paper pulp, discovery is in delignification period average K value 13 units that will descend: compare with conventional process and improve 30%, this delignification optionally advantage also proved by the viscosity of paper pulp relatively, average K value and viscosity by paper pulp are respectively 12.1 and 14.4 centipoises, as selection process of the present invention substantially the average K value under the identical viscosities (14.0 centipoise) be 8.3.

Also can be expressed as viscosity change be the function that the K value changes to the selectivity of delignification between unbleached pulp and the corresponding paper pulp of having handled, and when K value changes when beginning above 10 K value units, the selectivity of oxidation delignification sharply descends.K value for appointment changes, the variation that increases sharply along with viscosity, observe optionally and descend, for example changing the K value is 12 units, corresponding viscosity-modifying of the phase of giving is 12～13 centipoises, by contrast, K value (12) as same variation, the viscosity-modifying that obtains for the delignification paper pulp of handling with the best approach then is 6 centipoises, for the paper pulp that obtains with optimization process method of the present invention, as if high when changing 16 to 17K value units, the change of each K value no longer causes the change of viscosity, this result can be by showing the XII demonstration.

The table XII

Pine sulfate pulp character relatively

Common oxidation processes (O) is improved oxidation processes (O _m) unbleached pulp K value 21.9 20.5 viscosity, wooden stage pulp K value 12.1 8.3 viscosity are gone in (centipoise) 21.5 20.5K values and 1.02 1.0 oxidations of viscosity ratio, (centipoise) 14.4 14.0K values and viscosity ratio 0.84 0.59 caustic alkali pound/ton 39.4 46.0 delignifications, (%) 44.7 59.5 embodiment 6

A kind of southern pine paper pulp is to use improved oxidation delignification method (O in the preferred paper machine of 600TPD _m) produce, this method has condition and the represented condition of table X III that the table II combines with embodiment 4 and the 5 uniform alkali effects of describing, making the conventional paper pulp of O-program with this new method has and continues to utilize ozone fully to finish the needed various character of bleaching process, described as the embodiment of the invention, the paper pulp of oxidizing process has K value 7.9 (common O-program, K value about 12), the delignification pulp viscosity is 15 centipoises, and the height delignification that the method for oxidation of application enhancements obtains does not obviously reduce slurry viscosity, this then paper pulp is further bleached with ozone, and the paper pulp of repeatedly describing by embodiment that any process produced all has satisfied high-quality intensity and optical characteristics.

Paper pulp C/DED bleaching is finished in laboratory, as the relatively starting point of performance that provides described in the table X IV.

Table X III

Improved oxidation stage (the O of typical case _m) use PH temperature pulp density in the condition step %OD fiber

Chemicals (℃) (%) dipping (NaOH) 30%--22 3-4 oxidation (O ₂) 80 gauge pressures pound/inch ²10.2 110 27 (MgSO ₄) 0.1

Table X IV

Pine sulfate pulp C/DED conditions of bleaching

Step chemical preparation (%) PH value temperature (℃) pulp density (%)

C/D 2.4Cl ₂ 1.8 50 3.15

0.4ClO ₂

E 1.05NaOH 11.5 70 12

D 0.23ClO ₂ 4.2 60 12

The ozone bleaching process is to finish in experimental facilities reactor as shown in Figure 2, and the operating condition of experimental facilities reactor is shown in table X V.

Table X V

The typical operation conditions that small-scale is manufactured experimently reactor

Operating parameter numerical value or condition

Gas and paper pulp stream are to also flowing

Operation quota 6.5OD TPD*

Gas flow quota 58scfm

Pulp density 42%

Ozonization 1.18%

(annotate: because paper pulp contains consumption

The solid of the dissolving of ozone, used

Ozone amount increases)

1 minute paper pulp holdup time

Z _mStage K value 3.9

Z _mStage viscosity 11.8 centipoises

Z _mStage brightness 55%GEB

* every day dry tonnage

Ozone bleaching paper pulp is created in the small scale experiments device reaction device, extract in the laboratory and the chlorine dioxide treatment step then, as shown in the top table V, to produce the final paper pulp of bleaching of demarcating brightness, in the end the D stage, only 1.0% chlorine dioxide is used on the fiber.

It is satisfied that the pulp strength of ozone bleaching and optical characteristics are compared with common OC/DED, and comparative result is shown in table X VI and table X VII.

Table X VI

Pine O _mC/DED and O _mZ _mThe ED performance relatively

O _mC/DED O _mZ _mEDCSF tears coefficient breaking length CSF and tears coefficient breaking length 656 147 6.80 659 177 5.57511 113 8.00 510 146 6.93335 96 8.69 367 111 7.90217 101 8.69 178 100 8.20

Table X VII

Pine O _mZ _mThe ED luminosity response characteristics

ClO ₂(％) 0 0.5 1.0

Brightness (GEB%) 55.0 70.0 84.2 embodiment 7

In order further to show the scope of application and the effect of the inventive method, a kind of southern hardwood fiber, this fiber comes from the hardwood that comprises that mainly maple and oak mix, bench-scale testing with ozone bleaching is described among the embodiment 6 in the above, usually in the bench-scale testing reactor, use ozone treatment at the paper pulp oxidation step of producing on the 600TPD machine, the paper pulp K value of oxidation step is 5.7, and viscosity is 14.1.

The paper pulp part in O stage is bleached through conventional C/DED in the laboratory at last, and so that a relatively starting point to be provided, the C/DED condition is shown in table X VIII.

Table X VIII

Typical C/DED conditions of bleaching step (%) the chemical composition pH value temperature of hardwood (℃) pulp density (%) C/D 1.61Cl ₂1.8 50 3.15

0.26ClO ₂E 1.0NaOH 11.9 70 12D 0.35ClO ₂ 4.2 60 12

The treatment conditions of ozone reactor are as showing shown in the X IX pilot plant Z _mThe paper pulp in stage is bleached at last by common E and D stage (shown in the table XX) and is demarcated brightness, it only is 0.35% that the chlorine dioxide dosages in D stage is used on the OD fiber, with shown in table X XI and the table XX XII, firsthand information phase specific strength and light characteristic are gratifying.

Table X IX

Hardwood is manufactured experimently the operating condition of reactor on a small scale

Operating parameter numerical value or condition

Gas and paper pulp stream are to also flowing

Operation quota 9OD TPD

Air-flow quota 60scfm

Pulp density 36%

Ozone uses 0.86%

(annotate, because paper pulp contains dissolving

The solid of consumption ozone, institute

Increase with ozone amount)

1 minute paper pulp holdup time

Z _mStage K value 2.5

Z _mStage viscosity 11.9

Z _mStage brightness 63%GEB

The table XX

Be used for OZ _mED typical case conditions of bleaching step (%) the chemical composition pH value temperature of bardwood pulp (℃) pulp density E 1.0NaOH 12.0 70 12D 0.35ClO ₂4.36 60 12

Table X XI

Hardwood OC/DED and OZ _mThe ED characteristic relatively

OC/DED OZ _mEDCSF tears coefficient breaking length CSF and tears coefficient breaking length 526 89.9 4.41 515 88.3 4.52399 87.2 5.71 419 82.0 5.65262 79.5 6.26 293 70.5 6.56208 72.0 6.46 187 64.3 6.87

Table X XII

Hardwood OZ _mThe ED luminosity response characteristics

ClO ₂(％) 0 0.35

Brightness (GEB%) 64.0 84.4 embodiment 8

Be similar to the comparative test that embodiment 5 finishes Laboratory Production hardwood sulfate pulp, bardwood pulp comes from the mixed hardwood that mainly comprises maple and oak, in addition, find to compare with conventional oxidation technology (O), by oxidation delignification reactor with improved oxidation technology (O _m), the K value is significant to descend, 27 pounds/ton of the average corrosive agent input amount average out to of hard wood pulp, or 1.4% the K value that it has produced about 5 units during oxidation step descend, the corrosive agent of peer-level, obtain about 7.3 units of average K value decline by the improved oxidation technology process of the present invention, approximately increased by 50%.

This advantage on the delignification selectivity, also can show by comparing pulp viscosity, average K value and the viscosity of having found hardwood are respectively 7.6 and 16 centipoises, the present invention can obtain the K value and viscosity is 6 and 17.7, under same pulp viscosity, be 5.8 as the K value of the paper pulp that is untreated (16 centipoise).

The selectivity of delignification also can be stated as at unbleached pulp and improve accordingly that viscosity change is the function that the K value changes between the paper pulp that oxidation processes crosses, relatively the paper pulp handled of the paper pulp of being handled by conventional oxygen and the present invention is for the increase degree of delignification, aspect the delignification selectivity, there is bigger reduction, for changing 4 units aspect the K value, on average change into 4 centipoises for its viscosity of paper pulp of producing by the routine skill.On the contrary, same viscosity-modifying is with the paper pulp of improved method for oxidation production, its K value is changed to 7 units, represents with the delignification selectivity ratios, and the selectivity of improving one's methods is 1.8K value/centipoise, usual method is 1K value/centipoise, has increased by 80%, and its result is shown in table XX III.

Table XX III

Characteristics of pulp relatively (hardwood) comes the improved oxidation processes (O of the common oxidation processes of bleached pulp (O) _m) K value 12.3 13.0 viscosity (centipoise), 21.6 23.4K values and viscosity ratio 0.57 0.56 oxidation delignification stage pulp K value 7.6 6.0 viscosity (centipoise), 16.0 17.7K values and viscosity ratio 0.47 0.33 caustic alkali (pound/ton) 27.6 26.4 delignifications (%), 38.0 54.0 embodiment 9

The paper pulp in conventional oxidation delignification stage of having of 600TPD good quality paper machine (O) is come from utilization, a series of tests in the experimental provision reactor, have been finished, these experiments are to be used for explanation, on the ozone bleaching step of using southern hardwood, the influence of pH value, only the pH value of ozone stage is as variable under the represented condition in table XX IV, and reactor operating condition remains unchanged.

Table XX IV

Hardwood bench-scale testing reactor typical work condition

Running parameter numerical value or condition

Gas and paper pulp stream are to also flowing

Work quota 9OD TPD

Gas flow quota 40scfm

Pulp density 40%

Ozone uses 1%

(annotate: owing to contain in the paper pulp

Consume the solid of the dissolving of ozone,

So ozone amount increases)

1 minute paper pulp holdup time

As what found out from figure below XX V, the influence of pH value is that significantly lower pH value is favourable for the selectivity of improving bleaching process in the ozone bleaching process.

Table XX V

PH value passes through Z to the parameter PH5 PH4 PH3 PH2 that influences of hardwood _mZ is passed through in the change-2.79-3.17-3.16-3.67 of stage K value _mZ is passed through in the variation of stage brightness (GEB)+12.1+15.0+11.7+17.4 _mSection viscosity change (centipoise)-6.0-7.1-4.9-4.4 embodiment of institute 10

Relatively some parameter explanations are utilized OZ _mThe ED method is significant to the favourable influence of producing abundant bleached pulp, these typical operating datas and effluent measurement are collected from using CEDED and the OC/DED bleaching schedule operation paper machine on southern pine, these parameters to be used for and the OZ of those utilizations in embodiment 1 _mThe OZ of ED paper pulp and effluent _mThe effluent parameter of ED program output is compared, and can see Table the XX VI for common CEDED program, and table II above common OC/DED is visible and table III are for OZ _mTable IV above the ED program is visible and table V it should be noted that CEDED program effluent is C, E ₁, D ₁, E ₂And D ₂The effluent mixture, the OC/DED effluent is the mixture of C/D, E and D, OZ _mThe ED effluent is the effluent in D stage, each embodies the characteristic of several effluents, as showing shown in the XX VII, the ozone bleaching program has reduced the influence of bleaching process effluent to environment basically, for measuring color, adopted the EPA110.2 method, from this numeral no more than 2 pounds/ton of effluent pigment of the present invention discharging as can be seen, the BOD of five-day BOD ₅Value is not more than 2 pounds/ton, and the organic chloride total amount is not more than 2, even is lower than 0.8.

Table XX VI

Pine CEDED conditions of bleaching step chemical composition (%) PH value temperature (℃) pulp density (%) C 5.3Cl ₂4.10 40 3.15E 3.25NaOH, 11.3 70 12D 1ClO ₂3 60 12E 0.6NaOH, 11.6 70 12D 0.12ClO ₂3 60 12

Table XX VII

CEDED, OC/DED and OZ _mED bleaches relatively

Parameters C EDED OC/DED OZ _mED

BOD ₅(pound/ton) 34 21 1

Pigment (pound/ton) 367 83 is less than 1

TOCl (pound/ton) 74 0.8 embodiment 11

The bleaching of southern pine kraft pulp is three kinds of conversion programs that adopted basic DZED program.(OZ in first kind of program _mED) association with pulp bleaching uses common oxygen, improved ozone, caustic alkali extract and with ClO as shown in table IV and V ₂/ Cl ₂Ratio is 6: 1 chlorine dioxide as the series production of R-3 displaying, uses improved oxidizing process (O in second kind of program _m), and in the end the stage reuse R-3 type chlorine dioxide, in the third program, improved oxidizing process (O _m) be used again, and the R-8 ClO 2 solution is used to final stage with 95: 1 ratios, and table XX VIII has shown uses improved oxidizing process (O _m) good effect to environment that provides, the R-8 bleaching liquid also has good effect.

Table XX VIII

Pine kraft bleaching effluent order OZ _MED O _MZ _MED O _MZ _MED is stage ClO in the end ₂/ Cl ₂Ratio 6: 16: 1 95: 1TOCl ₃Pound/ram the loose soil with a stone-roller after sowing 0.8 0.3 0.2 embodiment 12

South torch pine paper pulp is starched pulping process with sulfate pulp and the sulfate pulp/AQ as top chart I and VIII description, these paper pulp are pressed embodiment 4 and 5 and are described further through common and the combined influence (to enlarge delignification minimum influence to pulp strength) of improved oxidation delignification with proof these processes on the ozone bleaching program, find out the adjection that these processes produce easily from table XX IX, energy influence last viscosity minimumly and obtain extremely low O _mZ _mThe K value of E is used for ozone bleaching process described above on the contrary, reaches to demarcate O _mZ _mThe ozone amount that EK value about 3.5 needs can significantly reduce, and adjection produces southern pine paper pulp in addition, and it can use O fully _mZ _mThe EP bleaching wherein only needs low-down O _mZ _mThe EK value is finished the sense peroxidating stage.

Table XX IX

Sulfate pulp/AQ paper pulp and improved oxidation (O _m) the additive effect parameter sulfate pulp+oxygen sulfate pulp/AQ+ oxygen sulfate pulp/AQ+O of pine paper pulp _m

Under (prior art) various situations, performance and used ozone amount ozone (%) 1.0 0.5 0.29 viscosity (centipoise) 8.9 11 11.8 embodiment 13 when the ozone use amount is 0.5%K value 6.2 3.4 1.8 viscosity (centipoise) 12.1 11 10.1 demarcation K values 3.5

Southern cork, i.e. torch pine is bleached that to demarcate brightness be 83GEB, has wherein used common CEDED program (shown in table XX VI), has used common OC/DED program (shown in top table II and III), has also used OZ _mED degree (shown in top table IV and V), the dirt of timber be by refining, and be added into OZ _mThe original unbleached pulp of DE is removed the ability of dirt to the degree of weight 0.75% to check that this program is compared with CEDED and OC/DED bleaching.Measured effective black area, bark and fragment, the dirt character of three kinds of programs is suitable.Embodiment 14

This embodiment shows the range of application of ozone bleaching process procedures of the present invention, the effective combination of suitable ozone and chlorine dioxide, reduced ambient influnence and running cost, and can be at the paper pulp that on the very wide brightness range of product, produces bleaching, shown in following table XXX, the various combinations of ozone and chlorine dioxide can make product brightness more than 65%GEB, have also kept the rational strength characteristic simultaneously.

The table XXX

OZ _mED conditions of bleaching step chemistry becomes PH temperature-time paper pulp to contain GEB K value viscosity ^*Rapid divide (%) value (℃) (branchs) measure (%) (%) (40mml) (centipoise) O _m(the given condition of table X III) 40 8.5 12.5Z _m0.43 2 22 1.5 43 50--10E 1.5 11.5 70 60 12----9.8D 0.5 4-5 70 180 12 65--9.6

0.7 70 9.6* are at O _mViscosity number after the step be based on both given data in the value of pushing away

Although to achieve these goals, here disclosed the present invention was planned well, yet be appreciated that, many improvement and embodiment still can be made by those skilled in the art, wish accompanying Claim topped all these improvement of energy and embodiment, make it to fall among spiritual essence of the present invention and the scope.

Claims

1. produce a kind of method of the paper pulp of evenly bleaching basically by lignocellulosic material, it comprises by chemical steaming makes a kind of intermediate products paper pulp with less wooden part, then thus obtained paper pulp is carried out the oxidation delignification, described method additional features is following step:

(a) pH of intermediate products paper pulp is transferred to the scope of 1-4;

(b) concentration of intermediate products paper pulp is transferred to the high concentration of 20-50%;

(c) intermediate products paper pulp is ground with reduce granularity to most of particle grain size less than 5 millimeters;

(d) to through a), b), c) the intermediate products paper pulp that obtains later on of step, carrying out delignification with admixture of gas ozoniferous handles, described processing is that the temperature and time of the intermediate products paper pulp of the usefulness that responded carries out to be enough to making ozone pass basically at the dynamic response device, make paper pulp pass through whole reactor transmission basically simultaneously, obtain a kind of more uniform basically delignification of the overwhelming majority that makes paper pulp thus.

2. method according to claim 1, wherein pulp particles has the size less than 5 millimeters.

3. method according to claim 1 and 2, it comprises by sulfate pulp-making, sulfate AQ slurrying or additional delignification carries out chemical steaming to the lignin fibre material.

4. method according to claim 1, wherein, described oxidation delignification step comprises that formation is low to moderate middle concentration paper pulp; Handle the paper pulp that this is low to moderate intermediate concentration with the aqueous solution of alkaline matter, give according to the amount of alkaline matter and make processing time and temperature, alkaline matter roughly is evenly distributed in the whole paper pulp that is low to moderate intermediate concentration; The concentration of paper pulp is brought up to high concentration; And make the high concentration paper pulp that obtains through high concentration oxidation delignification, to obtain intermediate products paper pulp.

5. method according to claim 1, wherein GE brightness is at least 50%, and the viscosity under definite intensity is greater than 10 centipoises, and wherein the amount of lignin represents that by 10 or littler K value (Ka Bo value) of intermediate products paper pulp viscosity is greater than 13 centipoises.

6. method according to claim 1, wherein lignocellulosic material is a cork, and described GE brightness is at least 50%, and described viscosity is being determined under the intensity greater than 10 centipoises, and wherein this lignin amount is by the K value representation of the 7-10 of intermediate products paper pulp, and this viscosity is greater than 13 centipoises.

7. method according to claim 1, wherein said ligno-cellulosic materials is a hardwood, its GE brightness is at least 55%, determining that this viscosity is 10 centipoises under the intensity, and wherein the lignin amount represents that by intermediate products paper pulp K value 5-8 viscosity is greater than 13 centipoises.

8. according to any one described method in the claim 5,6 or 7, wherein, after the ozone delignification, containing the lignin amount in the paper pulp is 3 to 4 expressions by the K value of bleached pulp.

9. method according to claim 1, it also is included in after the ozone delignification, with the GE brightness of brightener bleached pulp with the increase bleached pulp.

10. method according to claim 9, it also is included in relevant the giving under the fixed temperature of alkaline material amount with institute's chemical combination, the alkaline matter that makes q.s in the alkaline aqueous solution and bleached pulp mutually chemical combination to be dissolved in the major part of any lignin residual in the bleached pulp; Extract the part of alkaline aqueous solution then, thereby remove the whole lignin that dissolve in wherein basically, and before with the brightener bleaching, make the paper pulp that extracted.

11. method according to claim 9, wherein, described brightener is chlorine dioxide or peroxide.