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WO1997036040A1 - Pates organosolv blanchies a l'ozone - Google Patents

Pates organosolv blanchies a l'ozone Download PDF

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Publication number
WO1997036040A1
WO1997036040A1 PCT/IB1997/000524 IB9700524W WO9736040A1 WO 1997036040 A1 WO1997036040 A1 WO 1997036040A1 IB 9700524 W IB9700524 W IB 9700524W WO 9736040 A1 WO9736040 A1 WO 9736040A1
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WO
WIPO (PCT)
Prior art keywords
pulp
ozone
bleaching
stage
organosolv
Prior art date
Application number
PCT/IB1997/000524
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English (en)
Inventor
Adriaan R. P. Van Heiningen
Yonhao Ni
Original Assignee
Alcell Technologies Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcell Technologies Inc. filed Critical Alcell Technologies Inc.
Priority to AU24006/97A priority Critical patent/AU2400697A/en
Publication of WO1997036040A1 publication Critical patent/WO1997036040A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
    • D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/101—Bleaching ; Apparatus therefor in solvent medium

Definitions

  • Bleaching of chemical pulp consists of two process steps: delignification and brightening.
  • chlorine and chlorine dioxide are normally used in the first step, even when oxygen delignification and extended delignification technologies are applied to lower the lignin content of the pulp entering the bleach plant.
  • Chlorine dioxide is used almost exclusively in the brightening step.
  • total chlorine free (TCF) bleaching will be one of the preferred technologies in the near future.
  • Organosolv pulps obtained with an autocatalyzed organosolv pulping process such as the ALCELL* process as described in U.S. Patent No. 4,764,596 and International Publication Number HO 93/15261 have kappa numbers in the range of from about 20 to 30.
  • organosolv pulps have superior bleachability due, among other reasons, to the structure of residual lignin and the low metal content of the pulp which results in a highly selective response to alkaline extraction and/or oxygen delignification and other bleaching chemicals. This results in a reduction in kappa number and brightening without significant subsequent strength losses.
  • organosolv pulping such as ALCELL ® pulping
  • ALCELL ® pulping As compared to kraft pulping is that neither sodium sulfide nor sodium hydroxide are required. This eliminates the generation of malodorous sulfurous compounds and the requirement of a high capital cost recovery furnace.
  • organosolv brownstock usually has a higher kappa number than equivalent kraft pulps, organosolv pulps are easier to bleach.
  • ozone as a delignification agent presents two major drawbacks.
  • the first drawback which historically has prevented industrial introduction of ozone bleaching is the relatively high cost of ozone. This drawback has become less important in recent years, due to advances in ozone generation technology.
  • the second drawback with the use of ozone is cellulose degradation of the pulp.
  • This problem is addressed in the prior art which teaches that the cellulose degradation during ozone bleaching of pulp is greatly reduced when the pulp is impregnated with an acidified mixture of ethanol and water.
  • the present invention provides for a novel bleaching technology which is suited for integration with an organosolv pulping process such as the ALCELL ® process and which requires smaller amounts of bleaching compounds, other than oxygen and sodium hydroxide. Effluents resulting from the novel bleaching technology can be recycled for reuse in an organosolv pulping process such as the ALCELL ® process.
  • the novel bleaching technology described herein maintains a high pulp viscosity and replaces any subsequently required caustic extraction by an alcohol washing stage.
  • the novel bleaching technology allows the production of a high viscosity, low kappa number TCF semi- bleached organosolv pulp, without requirements for oxygen delignification, caustic extraction and associated effluent facilities needed to treat the filtrates in the absence of a recovery reboiler.
  • the semi bleached organosolv pulp can subsequently be brightened with non- chlorine chemicals to full brightness while maintaining good strength properties.
  • the final brightness of the fully bleached pulp is over 90 ISO with no significant loss in viscosity up to about 4 cps and without the use of chlorine-containing chemicals.
  • Brownstock pulp obtained from an organosolv pulping process is bleached with ozone (Z stage) and washed with an aqueous solution of a lower alkyl alcohol to remove any dissolved lignin (A stage) . Prior to ozonating the pulp, the pulp is washed with an aqueous solution of a lower alkyl alcohol (A Q stage) . The result is an A Q Z ⁇ A pulp.
  • the washing and ozonation stages can be repeated in sequence to yield a multiply ozonated pulp.
  • the washed and ozonated pulp is further bleached with a caustic solution in the presence of oxygen and a peroxy compound.
  • the result is a semi-bleached A Q Z ⁇ AEOP pulp.
  • the semi-bleached pulp is further treated with a peroxy compound and then is again treated with a caustic solution in the presence of oxygen and a peroxy compound.
  • the result is a fully bleached pulp AoZnAEop ⁇ PaEop2 with a brightness over 90 ISO and no significant loss in pulp viscosity.
  • Another object of the invention is the removal of filtrates resulting from washing the pulp with the aqueous alcohol solution.
  • the filtrates are returned for reuse in said process.
  • Figure 1 is a process flow sheet illustrating the method of the present invention wherein an organosolv pulp is bleached in an ZnA stage.
  • Figure 2 shows the effect of temperature on the ozone delignification efficiency.
  • Figure 3 shows the effect of temperature of the ozone (lignin-carbohydrate) selectivity.
  • Figure 4 shows the effect of ethanol concentration on the ozone delignification efficiency.
  • Figure 5 shows the effect of ethanol concentration on the ozone (lignin-carbohydrate) selectivity.
  • Figure 6 shows the effect of A-stage filtrate recycle on the ozone delignification efficiency.
  • Figure 7 shows the effect of A-stage filtrate recycle on the ozone (lignin-carbohydrate) selectivity.
  • Figure 8 shows the effect of scaleup on the ozone (lignin-carbohydrate) selectivity.
  • the invention provides for a novel bleaching technology of organosolv pulps obtained by an autocatalyzed process such as the ALCELL ® process.
  • the pulps referred to herein are those obtained after organosolv digestion and cooking. They are generally referred to as brownstock pulp and have typical kappa numbers of approximately 25 to 35, depending on the wood species and other factors. By comparison, kappa numbers for kraft hardwood pulps typically will vary between about 15 and 21.
  • the processes of this invention produce a fully bleached pulp with a brightness over 90 ISO and without a substantial decrease in pulp viscosity, namely a decrease in pulp viscosity of up to about 4 cps. Also is produced a semi-bleached pulp with a brightness of over 65 ISO and without a substantial decrease in pulp viscosity, to up to 4 cps and a kappa number of from about 2 to about 6.
  • the novel process of the invention is shown in Figure 1.
  • the pulp is withdrawn from extractor 10 through line 12.
  • the pulp is washed as indicated at 14 to reduce the lignin content in the brownstock ( Q stage) .
  • the pulp is preferably washed by displacement washing with an aqueous solution of a lower alkyl alcohol which can be preferably ethanol or methanol, the lower alkyl alcohol in a range from about 30 to about 90% by weight.
  • the pulp is washed at a temperature of from about 10 to 80°C, preferably at about 60 to about 70°C, to achieve a reduction of kappa number by a factor of about 35 to about 55% with no significant loss in pulp viscosity.
  • the filtrate from the alcohol wash stage 14 is treated in the black liquor recovery.
  • the alcohol washing can also be accomplished as a final in-digester wash in extractor 10 with a near neutral or slightly acidic mixture of the aqueous solution of the lower alkyl alcohol, the solution having a pH preferably greater than 3.5 (measured at room temperature) .
  • the concentration of the alcohol in the alcohol-water mixture used for in-digester washing can vary from about 30 to about 90% (by weight) , preferably from about 50 to about 70% (by weight) .
  • the temperature of the in-digester wash is performed at the highest possible temperature but is preferably less than about 170°C.
  • the spent wash liquor obtained from the in-digester wash is sent to the black liquor recovery or is used as described in International Publication Number WO 93/15261.
  • the washed pulp 16 is discharged to blow tank 18 for storage and consistency adjustment. From blow tank 18, the pulp is thickened at 20 by pressing to from about 10 to about 70% consistency to minimize carry over of the hot alcohol-water mixture from wash stage 14 to the ozone stage at 26. The hot alcohol-water mixture is removed and recycled through line 13 for reuse in wash stage 14. The alcohol-water mixture can also be reused for in-digester washing or as part of the cooking solvent in extractor 10.
  • the thickened pulp is acidified in stirred tank 22 by addition of an organic or mineral acid, for example acetic and sulfuric acids.
  • the pH after acidification ranges from about 1.5 to about 5, preferably from about 2 to about 6.
  • the acidification is preferably performed on low consistency pulp of from about 1 to about 4% (by weight) .
  • Stirred tank 22 can be selected such that it can handle the pulp from 20, the acid and the recycle stream from press 35.
  • blow tank 18 can be positioned right after extractor 10.
  • the pulp withdrawn from extractor 10 can be discharged to blow tank 18 for storage and consistency adjustment prior to washing.
  • the pulp from blow tank 18 is then processed as described in alcohol wash stage 14.
  • the acidified pulp from 22 is pressed at 35 to a high consistency of from about 10 to about 70%, preferably from about 20 to about 60% (by weight) . Any excess acidified alcohol-water mixture is removed from press 35 and recycled to 22. The acidic recycle is cooled to from about 0 to about 30°C, preferably to from about 5 to about 15°C. Following pressing, if required, the pulp from 35 is fluffed at 24.
  • the thickened and fluffed pulp is introduced to the ozone stage 26 (Zn stage) .
  • Ozone is introduced at 26 at a concentration of from about 3 to about 15% by weight with oxygen, air or nitrogen as a carrier gas and the pulp is subjected to ozone bleaching in the presence of the aqueous solution of a lower alkyl alcohol, such as for example ethanol or methanol, preferably ethanol from about 10 to 90% by weight, preferably from about 30 to about 70% by weight at an ozone charge varying from about 0.5 to about 3%, preferably from about 1 to about 2.5% based on o.d. weight of pulp.
  • the temperature in the ozonation stage is controlled from about 0° to about 30°C, preferably from about 5 to about 15°C and the pH is maintained in a range from about 1.5 to 5, preferably from about 2 to about 6.
  • the ozonated pulp is diluted at 28 with an aqueous solution of a lower alkyl alcohol, preferably an aqueous solution of ethanol of from about 30 to about 90% by weight so that the pulp consistency reaches from about 1 to about 4% (by weight) .
  • the pH is adjusted in 28 to near neutral or slightly acidic by addition of a basic solution, preferably to a pH greater than about 3.5.
  • the diluted and neutralized pulp from 28 is washed at 30 (A stage) with an aqueous solution of a lower alkyl alcohol, preferably ethanol of from about 30 to about 90 % by weight, preferably from about 50 to about 70% by weight to remove the dissolved lignin.
  • the pulp washing is preferably performed in a displacement mode.
  • the washing temperature is from about 10 to about 80°C, preferably from about 60 to 70°C.
  • the resulting alcohol washed pulp is subsequently washed in multistage countercurrent washing equipment 32 by introduction of water or bleaching filtrates from 34 to recover the alcohol in the pulp slurry leaving 30.
  • Filtrates from the A stage at 30 are removed and returned to wash stage 14 and introduced via line 13. The filtrates are also used for dilution at stage 28.
  • wash stage 30 a A Q Z ⁇ A pulp is produced which can be subjected to a sequential A Q Z ⁇ A stages to yield oZnAZnA or AoZnAZnAZnA pulps using essentially the same conditions of ozonation and washing.
  • the single or multiple ozonated pulp can be further subjected to bleaching.
  • One preferred sequence is A ⁇ ZnAEop to produce a semi-bleached pulp with a brightness over 65 ISO, a kappa number of from about 2 to about 6, and no significant loss in viscosity, up to 4 cps below that of the unbleached pulp.
  • Another preferred sequence is A 0 ZnAEop ⁇ PaEop2 which produces a fully bleached, totally chlorine free pulp (TCF) with a brightness over 90 ISO and no significant loss in viscosity, up to about 4 cps.
  • the pulp at a consistency of from about 10 to about 25%, preferably at a consistency of from about 15 to about 20% is mixed with a caustic solution containing from about 0.5 to about 2.5%, preferably from about 1 to about 2% by weight sodium hydroxide based on o.d. weight of pulp.
  • the pulp slurry thus formed is mixed at high shear with oxygen to maintain an oxygen pressure of from about 50 to about 80 psig, preferably from about 60 to about 70 psig.
  • the temperature is preferably from about 85 to about 110°C, preferably from about 90 to about 105°C.
  • the total reaction time is from about 0.5 to about 3 hours, preferably from about 1 to about 2 hours.
  • the Eop treated pulp at a consistency of from about 8 to about 25%, preferably from about 10 to about 20% is reacted with a peroxy compound, preferably peracetic acid of from about 0.3 to about 1.5%, preferably from about 0.5 to about 1% based on o.d. pulp weight.
  • the final pH is from about 3.5 to 8.5, preferably from about 4 to about 7.5.
  • the peroxy treated pulp is reacted in a second Eop2 stage to yield a fully bleached pulp.
  • the pulp at a consistency of from about 10 to about 25%, preferably from about 15 to about 20% is mixed with a caustic solution containing from about 0.5 to about 2%, preferably from about 0.75 to about 1.5% by weight sodium hydroxide.
  • the pulp slurry thus formed is mixed at high shear with oxygen to maintain an oxygen pressure of from about 50 to about 80 psig, preferably from about 60 to about 70 psig. From about 0.25 to about 2%, preferably from about 0.5 to about 1.5% hydrogen peroxide based on o.d.
  • weight of pulp is added and additional chemical agents may be added such as magnesium sulfate from about 0.02 to about 0.5%, preferably from about 0.05 to about 0.2%.
  • DTPA up to 0.4%, preferably up to 0.2% based on o.d. weight of pulp can also be added.
  • the temperature is preferably from about to about 55 to about 80°C, preferably from about 60 to about 70°C.
  • the pressure is maintained at from about 50 to about 80 psig, preferably from about 60 to about 70 psig.
  • the total reaction time is from about 1 to about 3 hours, preferably from about 1.5 to about 2.5 hours.
  • the AoZnAZnAZnA pulp can be further bleached with chlorine dioxide at standard conditions in one, preferably two stages with a water wash in between the chlorine dioxide stages.
  • the fully bleached pulp has a brightness of from about 85 to about 87 ISO with no significant loss in viscosity relative to the unbleached pulp.
  • an alkaline extraction can replace the water wash between the two chlorine dioxide stages.
  • the conditions of the alkaline extraction stage are a charge of NaOH from about 1 to about 3%, a pulp consistency of from about 8 to about 20%, a temperature from about 60 to about 80°C and for about 1 to about 3 hours.
  • the chlorine dioxide charge in the second D stage is from about 0.3 to about 0.5 by weight.
  • the final fully bleached pulp has a brightness of from about 88 to about 89 ISO with no significant loss in viscosity.
  • Example 1 The experiments in Examples 1 to 9 were performed using 4 gram to 10 gram o.d. organosolv brownstock obtained from the ALCELL ® process in a 1 or 2 liter reactor or 200 gram o.d. brownstock in a 20 liter reactor.
  • Example 1
  • the lignin content in the pulp brownstock can be reduced by displacement washing with an aqueous solution of ethanol. Washing conditions were: 70% by weight ethanol concentration, about 10% pulp consistency and a temperature of 63°C. A kappa number reduction by a factor of about 55% was achieved with no loss of pulp viscosity. The initial kappa number of the pulp was 53.9 and the viscosity was 25.9 cps. The washed pulp has a kappa number of 29.3 and a viscosity of 26.0 cps. The alcohol-washed pulp was pressed to a consistency of about 35%, fluffed and then subjected to ozone bleaching with ethanol.
  • the pulp slurry was heated to 70°C and kept at this temperature for about 1 hour.
  • the pulp slurry was cooled to room temperature and its pH adjusted to 2.
  • the excess amount of ethanol liquor was removed by squeezing the pulp to a consistency of about 35%.
  • the pulp was then fluffed, and further subjected to a second stage of ozone bleaching under the same conditions as in the first Zn stage.
  • the ozone charge and consumption of the second Zn stage are 1.0% and 0.86% (by weight on o.d. pulp) respectively.
  • the second ozone stage is then followed by a second A stage with a 70% ethanol solution at a 10% pulp consistency and 70°C for 1 hour.
  • the semi-bleached pulp of Example 1 which has a kappa number of 6.4 and a viscosity of 19.6 cps was further bleached by two stages of chlorine dioxide treatment with a water washing stage in between.
  • the chlorine dioxide charges were 1.0% and 0.5% based on o.d. weight of pulp, respectively in the first and second stages.
  • Other conditions of the first D stage are 10% consistency, 45°C, and 1 hour reaction time, while the second D stage was performed at 50°C for 2 hours under otherwise the same experimental conditions.
  • the fully bleached pulp has a brightness of 85.7% ISO and a viscosity of 20.1 cps. Its physical properties are compared in Table 2 to those of a standard (ODED) organosolv fully bleached pulp.
  • ODED ODED
  • the organosolv pulp with a kappa number of 53.5 and viscosity of 23.6 cps can be semi-bleached using the sequence A Q ZIIAEOP.
  • the bleaching conditions were as follows with all chemical charges based on o.d. pulp weight: Ozone stage 2% O3 charge, 9°C, 70% ethanol in water; Eop stage 1.5% NaOH, 0.5% H 2 0 , 0.5% MgS0 , 0.2% DTPA, 105°C 60 psig O2 , 1 hr, 17% consistency. Results are shown in Table 3.
  • the organosolv pulp with a kappa number of 53.5 and a viscosity of 23.6 cps was treated in the sequence A 0 ZnAEop ⁇ PaEop2.
  • the conditions of bleaching were as follows: Ozone stage 2% O3 charge, 9°C, 30% ethanol; Eop !
  • a Q Z ⁇ A bleached organosolv pulp exhibits good strength properties. These properties were determined for a brownstock pulp with a kappa number of 53.5 and viscosity of 23.6 cps after an A Q Z ⁇ A sequence. A 70% ethanol solution at 60°C was used in both the Q and A stages. The kappa number of the Q washed pulp was 30.6. Subsequently, this pulp was subjected to Zn bleaching (70% ethanol, 10°C) at a 2.5% ozone charge. The resulting A Q ZIIA pulp has a kappa number and viscosity of 8.8 and 20.1 cps respectively. The strength properties of the A Q Z ⁇ A pulp are listed in Table 5.
  • an organosolv pulp bleached by a standard A Q ODED sequence Comparing both pulps, one can conclude that the strength properties of the A Q ZIIA pulp are at least equivalent to those of an ODED bleached pulp.
  • Table 5 Also listed in Table 5 are the properties of a (ZnA)3 DWD organosolv pulp. The viscosity of this ODED bleached pulp is the same as that of the present ZnA pulp. It can be seen that this three stage ZnA pulp has strength properties which surpass that of an ODED pulp. A brightness of 88.4% was obtained when the water wash (W) between the two D stages was replaced by an E stage (1% NaOH on pulp) .
  • This example demonstrates the effect of temperature on Zn bleaching of a well-washed organosolv brownstock with a kappa number of 26.7 and a viscosity of 22.9 cps impregnated with a 70% ethanol-water mixture acidified with H2SO4.
  • the Zn bleached pulps were subjected to a displacement washing A-stage with 70% ethanol-water at 60°C and 10% pulp consistency. The kappa number and viscosity of these ZnA pulps were determined. The results are shown in Figures 2 and 3.
  • Figure 2 shows that the delignification efficiency of ZnA bleaching is not significantly affected by the temperature of ozone bleaching over the range of - 10°C to 25°C.
  • Figure 2 also shows that the delignification efficiency decreases considerably when the ozone consumption increases above about 1%. For example, at an ozone consumption of 1% the kappa number decreases from 27 to about 12, while a kappa number reduction of only 6 is achieved by the next 1% ozone consumption. Further increase in ozone consumption leads to even less delignification.
  • ozone consumption should not exceed 2%.
  • Figure 3 shows that the ozone (lignin- carbohydrate) selectivity improves at lower temperatures. For example, when the temperature decreases from 25°C to 10°C, the pulp viscosity increases by about 4 cps at a kappa number of about 5.
  • Example 7 shows that the ozone (lignin- carbohydrate) selectivity improves at lower temperatures. For example, when the temperature decreases from 25°C to 10°C, the pulp viscosity increases by about 4 cps at a kappa number of about 5.
  • This example illustrates the effect of ethanol concentration during the ozone stage on the properties of ZnA pulp at 10°C.
  • Eight solutions with an ethanol concentration of respectively 0%, 5%, 10%, 20%, 30%, 50%, 60%, 70% were used.
  • the ethanol-water mixtures were all acidified to pH 2.
  • Standard conditions of 70% ethanol solution, 60°C and 10% consistency were again used in the A stage. The results are shown in Figures 4 and 5.
  • Figure 4 shows the effect of ethanol concentration on the ozone delignification efficiency.
  • the kappa number reduction at a given ozone consumption is almost independent of the ethanol concentration. This indicates that the presence of ethanol does not lead to an increase in ozone consumption and suggests that the reaction between ozone and ethanol is relatively small.
  • Figure 4 again shows that the ozone delignification efficiency decreases significantly when the ozone consumption increases.
  • a ZnA kappa number of about 7 is obtained from an unbleached pulp with a kappa number of about 27.
  • Figure 5 shows the effect of ethanol concentration on the ozone (lignin-carbohydrate) selectivity.
  • the viscosity of a kappa number of 7 for a ZnA pulp is about 42% lower than that of the unbleached pulp (13.3 cps versus 22.9 cps).
  • This compares to a viscosity decrease of only about 18% (from 22.9 to 18.8 cps) at the same delignification degree when 10% ethanol is present in the impregnation liquor during ozone bleaching. This represents a significant reduction in carbohydrate degradation.
  • the kappa number of the A Q washed pulp increased from 28.9 to 29.1 in respectively the first and second sequence and the viscosity of the Ao treated pulp remained unaffected at 20.6 cps in both sequences.
  • the kappa number and viscosity after the A Q Z ⁇ A treatment in the first and second sequences were 9.9 and 17.9 cps, and 11.7 and 18.3 cps respectively.
  • the A-stage filtrate from the second sequence contained 409 ppm lignin which is 17% higher than that was obtained in the first sequence.
  • Figure 6 shows that the presence of lignin in the A-stage filtrates decreases the lignin removal during the A Q ZIIA sequence by about 2 kappa number units at an

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Abstract

Cette invention se rapporte à une pâte organosolv blanchie qui est obtenue dans un procédé consistant à blanchir une pâte organosolv avec de l'ozone (26), à laver la pâte ainsi ozonisée avec une solution aqueuse d'un alcool d'alkyle inférieur (30) pour éliminer la lignine dissoute dans la pâte, à retirer les filtrats de la solution de lavage à l'alcool contenus dans la pâte lavée et à recycler les filtrats ainsi retirés pour qu'ils puissent être réutilisés dans le processus (13, 28). La pâte lavée ozonisée subit ensuite un nouveau blanchiment (34) pour former une pâte entièrement blanchie d'une blancheur de plus de 90 ISO sans qu'il soit nécessaire de recourir à des agents chimiques contenant du chlore.
PCT/IB1997/000524 1996-03-25 1997-03-25 Pates organosolv blanchies a l'ozone WO1997036040A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU24006/97A AU2400697A (en) 1996-03-25 1997-03-25 Ozone-bleached organosolv pulps

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US62152096A 1996-03-25 1996-03-25
US08/621,520 1996-03-25

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010071867A2 (fr) 2008-12-19 2010-06-24 E. I. Du Pont De Nemours And Company Traitement de la biomasse à l’organosolv et à l’ozone pour améliorer la saccharification enzymatique
US8216809B2 (en) 2008-12-19 2012-07-10 E I Du Pont De Nemours And Company Organic solvent pretreatment of biomass to enhance enzymatic saccharification
US8603295B2 (en) 2009-04-23 2013-12-10 Greenfield Specialty Alcohols Inc. Separation of reactive cellulose from lignocellulosic biomass with high lignin content
US9187862B2 (en) 2010-11-05 2015-11-17 Greenfield Specialty Alcohols Inc. Bagasse fractionation for cellulosic ethanol and chemical production
US9255189B2 (en) 2011-07-28 2016-02-09 Greenfield Specialty Alcohols Inc. Ethanol production with two stage continuous steam pre-treatment of lignocellulosic biomass
US9932707B2 (en) 2010-11-05 2018-04-03 Greenfield Specialty Alcohols Inc. Bagasse fractionation for cellulosic ethanol and chemical production
WO2024112241A1 (fr) * 2022-11-24 2024-05-30 Valmet Ab Procédé de manipulation de filtrats dans un processus de production de pâte de cellulose blanchie à partir d'un matériau textile recyclé

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4956048A (en) * 1989-04-17 1990-09-11 Westvaco Corporation Method of alcohol washing brownstock pulp prior to a chlorination bleaching stage
EP0472820A2 (fr) * 1990-08-17 1992-03-04 Alcell Technologies Inc. Procédé et appareil pour la mise en pâte en continu en milieu solvant et le lavage
EP0480469A2 (fr) * 1990-10-12 1992-04-15 Alcell Technologies Inc. Pâtes de bois sans chlore et procédé pour leur obtention
WO1993015261A1 (fr) * 1992-01-29 1993-08-05 Allcell Technologies Inc. Reduction en pate de materiaux vegetaux fibreux et recuperation de sous-produits resultants
WO1994010377A1 (fr) * 1992-10-23 1994-05-11 Macmillan Bloedel Limited Blanchiment a l'ozone ameliore
WO1995010656A1 (fr) * 1993-10-15 1995-04-20 Macmillan Bloedel Limited Recuperation du methanol

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4956048A (en) * 1989-04-17 1990-09-11 Westvaco Corporation Method of alcohol washing brownstock pulp prior to a chlorination bleaching stage
EP0472820A2 (fr) * 1990-08-17 1992-03-04 Alcell Technologies Inc. Procédé et appareil pour la mise en pâte en continu en milieu solvant et le lavage
EP0480469A2 (fr) * 1990-10-12 1992-04-15 Alcell Technologies Inc. Pâtes de bois sans chlore et procédé pour leur obtention
WO1993015261A1 (fr) * 1992-01-29 1993-08-05 Allcell Technologies Inc. Reduction en pate de materiaux vegetaux fibreux et recuperation de sous-produits resultants
WO1994010377A1 (fr) * 1992-10-23 1994-05-11 Macmillan Bloedel Limited Blanchiment a l'ozone ameliore
WO1995010656A1 (fr) * 1993-10-15 1995-04-20 Macmillan Bloedel Limited Recuperation du methanol

Cited By (8)

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Publication number Priority date Publication date Assignee Title
WO2010071867A2 (fr) 2008-12-19 2010-06-24 E. I. Du Pont De Nemours And Company Traitement de la biomasse à l’organosolv et à l’ozone pour améliorer la saccharification enzymatique
WO2010071867A3 (fr) * 2008-12-19 2010-09-02 E. I. Du Pont De Nemours And Company Traitement de la biomasse à l’organosolv et à l’ozone pour améliorer la saccharification enzymatique
US8216809B2 (en) 2008-12-19 2012-07-10 E I Du Pont De Nemours And Company Organic solvent pretreatment of biomass to enhance enzymatic saccharification
US8603295B2 (en) 2009-04-23 2013-12-10 Greenfield Specialty Alcohols Inc. Separation of reactive cellulose from lignocellulosic biomass with high lignin content
US9187862B2 (en) 2010-11-05 2015-11-17 Greenfield Specialty Alcohols Inc. Bagasse fractionation for cellulosic ethanol and chemical production
US9932707B2 (en) 2010-11-05 2018-04-03 Greenfield Specialty Alcohols Inc. Bagasse fractionation for cellulosic ethanol and chemical production
US9255189B2 (en) 2011-07-28 2016-02-09 Greenfield Specialty Alcohols Inc. Ethanol production with two stage continuous steam pre-treatment of lignocellulosic biomass
WO2024112241A1 (fr) * 2022-11-24 2024-05-30 Valmet Ab Procédé de manipulation de filtrats dans un processus de production de pâte de cellulose blanchie à partir d'un matériau textile recyclé

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