EP0177113B1 - Méthode de lavage d'une pâte cellulosique - Google Patents

Méthode de lavage d'une pâte cellulosique Download PDF

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Publication number
EP0177113B1
EP0177113B1 EP19850302568 EP85302568A EP0177113B1 EP 0177113 B1 EP0177113 B1 EP 0177113B1 EP 19850302568 EP19850302568 EP 19850302568 EP 85302568 A EP85302568 A EP 85302568A EP 0177113 B1 EP0177113 B1 EP 0177113B1
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Prior art keywords
pulp
carboxy
mat
zero
solvent
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German (de)
English (en)
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EP0177113A1 (fr
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James E. Maloney
Richard E. Freis
Thomas R. Oakes
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Henkel Corp
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Henkel Corp
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    • 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

Definitions

  • This invention relates to a method of removing and recovering spent or excess cooking chemicals and pitch from virgin or primary cellulosic fiber. More particularly, the invention relates to an improved method of brown stock washing to enhance the recovery of spent cooking chemical residues and excess cooking chemicals, and remove non-cellulosic materials such as lignin, fatty acid soaps, and resin acids.
  • logs are reduced to wood chips, which are fed into a digester.
  • "Liquor" an aqueous solution obtained from the later described wash step and containing dissolved and residual cooking chemicals, spent cooking chemical residue and cellulosic contaminants, and "white liquor”, another by-product of the pulping process known in the art, are fed into the digester, primarily for dilution.
  • Cooking chemicals are also added as required. The cooling chemicals are described hereinafter.
  • the contents of the digester are brought to a relatively high temperature and pressure, for example about 177°C (about 350°F) at a pressure of about 760000 N/m 2 (about 110 pounds per square inch).
  • the wood chips are "cooked" in the digester under these conditions to reduce the wood chips to pulp. Typically, under these conditions, the wood chips are cooked from about 1 to 5 hours. The cooking can be carried out in batch or continuous digesters.
  • brown stock The cooked wood chips or pulp in the aqueous medium after digestion is referred to as "brown stock".
  • the brown stock consists generally of two phases, the pulp, and the liquor or liquid phase of the digester contents. However, typically after digesting, oversized chips, insufficiently cooked chips, or knots remain. These components are generally removed from the brown stock by knotters which typically consist of coarse screens.
  • the brown stock is transferred to a washer for a washing step.
  • the washing process involves a series of washers which separate the pulp from the liquor, and progressively clean the pulp by removal of cooking chemicals, cooking chemical residues, and non-cellulosic contaminants.
  • the brown stock was filtered in a false bottom tank or diffuser into which the digester was discharged.
  • the liquor was drained through the false bottom, and the pulp was washed by gravity displacement of the liquor with wash water.
  • Other types of washers such as a pressure washer are also known in the art.
  • the rotary vacuum drum or cylinder or vacuum washer is more typically used.
  • the vacuum washer is generally a wire cylinder or drum that rotates in a vat containing the brown stock (i.e. the pulp and liquor mixture).
  • the lower section of the drum is immersed in the brown stock.
  • Vacuum is applied inside the drum as it rotates through the brown stock.
  • the liquor drains through the surface of the wire drum into the interior, leaving a layer of pulp on the outside face of the drum.
  • the layer of pulp is held in place by the vacuum force inside the drum, from where it is conducted away.
  • the layer of pulp continues to build, forming a mat or sheet, as the submerged portion of the drum rotates through the brown stock in the vat. Liquor continues to drain from the pulp of fiber mat as a result of the differential pressure between the external atmosphere and the vacuum within the cylinder.
  • Washing action is generally provided by showers located over the pulp sheet. Water is sprayed onto the pulp sheet to displace the liquor from the sheet on the drum as the drum continues to rotate. The vacuum force draws the water into the sheet, where it displaces the liquor. The liquor drains out the other side of the sheet into the inside of the cylinder, where it drains away to a filtrate storage tank for reuse, for example as wash water for a more contaminated sheet which has formed on another of the washers in the series.
  • pulp sheet is removed from the face of the wire by a doctor blade.
  • the surface of the sheet where the wash water is applied becomes cleaner than the pulp adjacent to the cylinder at the bottom of the sheet, since the wash water becomes more concentrated in liquor as it passes through the sheet. Consequently, where a series of washers is utilized, the pulp sheet obtained from the first vacuum washer is generally repulped to provide a more uniformly clean pulp before traveling over the second vacuum washer. This repulping step is generally repeated between each vacuum washer in the sequence.
  • the pulp fibers are agitated at a low consistency (i.e. the pulp is very dilute) in order to facilitate scrubbing.
  • the low consistency also aids in achieving a lowered concentration of dissolved solids, prior to collection of the pulp on the next washer in the series.
  • Low consistency promotes diffusion of the contaminated liquor from the pulp in the repulping step.
  • the pulp medium and the wash water are generally arranged to flow countercurrent to each other.
  • Fresh water is typically used to wash the pulp sheet on the last stage washer.
  • the filtrate that was pulled through pulp sheet on each washer is used to wash the pulp on the preceding washer. This aids in minimizing dilution of the liquor which is separated from the pulp, and from which cooking chemicals or cooking chemical residues are to be recovered as described hereinafter.
  • the cooking chemicals used in pulping mills are known in the art. Briefly, the cooking system is generally either kraft or sulfite. Other cooking systems are also known in the art.
  • the kraft system generally involves the use of sodium hydroxide and sodium sulfide in the digester to aid in decomposition of the wood fibers to produce pulp.
  • the sodium may be added as sodium sulfate, sodium carbonate, or similar sodium compounds.
  • the sulfite system typically involves the use of S0 2 and magnesium, calcium, sodium or ammonia.
  • the kraft mill generates "black liquor", while the counterpart in the sulfite mills is referred to as "red liquor”.
  • red liquor the term “liquor” refers to both “red” and “black” liquor, and the aqueous phase of the pulp mixture resulting from other pulp processing methods such as those described below.
  • Some pulping mills form pulp from wood products without the use of cooking chemicals.
  • Several such pulping processes are known, including mechanical processes such as the groundwood process, use of a refiner to create refiner mechanical pulp, or use of heat to create thermomechanical pump. Most such processes rely on heat and mechanical action to break down the wood fibers.
  • Other processes, such as the NSSC process rely on both chemical and mechanical action. While these mechanical, thermomechanical, or semi-chemical processes typically do not involve washing steps, where washing steps are used the methods of this invention can aid in cleaning the pulp and recovering organic contaminants.
  • the brown stock will contain many impurities from the pulping process, including excess cooking chemicals and spent cooking chemicals (where chemicals are used in the pulping), and also a variety of organic contaminants such as resin acids, fatty acid soaps and the like originating in wood.
  • the contaminants occlude to the pulp fibers, and are also present in the aqueous phase of the brown stock. It has been found that in general, the contaminants of black liquor and the corresponding pulp are principally alkali lignin, hydroxy acids and lactones, and sodium. Generally, black liquor is also contaminated with acetic acid, formic acid, sulfur, extractives, and methanol.
  • Red liquor obtained through the sulfite process
  • the corresponding pulp has been found to be contaminated with lignosulfonate, monosaccharides (mannose, xylose, galactose, glucose and arabinose), poly and oligosaccharides, calcium, aldonic acids, sugar-sulfonates, extractives, acetic acid, methanol, and glucuronic acid.
  • lignosulfonate monosaccharides (mannose, xylose, galactose, glucose and arabinose)
  • poly and oligosaccharides calcium, aldonic acids, sugar-sulfonates, extractives, acetic acid, methanol, and glucuronic acid.
  • an improved method of removing spent or excess cooking chemical compounds or organic contaminants from chemically or mechanically prepared virgin pulp characterised in that it comprises (a) forming a fiber mat of chemically or mechanically prepared virgin pulp; and (b) forcing an aqueous solution comprising a substituted oxyethylene glycol non-ionic surfactant, a water soluble low molecular weight polyelectrolyte dispersant and a solvent into and through the fiber mat, wherein the non-ionic surfactant has the formula: wherein Ar is an aromatic residue, a is zero or 1, R is an aliphatic group that contains from 6 to 24 carbon atoms when a is zero and from 6 to 18 carbon atoms when a is 1, n is from 3 to 50, m is from zero to 50, and Y is hydroxy or benzyl ether with the proviso that, when m is zero, Y is benzyl ether, and wherein the polyelectrolyte dispersant has the formula:
  • the present invention also provides a method of recovering excess or spent cooking chemical compounds or organic contaminants from an aqueous pulping medium comprising chemically or mechanically prepared virgin pulp and excess or spent chemical compounds or organic contaminants, characterised in that it comprises (a) combining the aqueous pulping medium with a substituted oxyethylene glycol non-ionic surfactant, a water soluble molecular weight polyelectrolyte dispersant, and solvent; (b) substantially separating the chemically or mechanically prepared virgin pulp from the aqueous pulping medium; and (c) after step (b), removing excess or spent cooking chemical compounds or organic contaminants from the aqueous pulping medium; wherein the non-ionic surfactant and the polyelectrolyte dispersant have the formula (I) and (II) given above.
  • the present invention involves use in the wash process of the nonionic surface active agent or surfactant in combination with the dispersant and the solvent.
  • the surface has the formula (I) given above wherein Ar is preferably monocyclic and R is typically saturated.
  • the foregoing structural formula (I) can be considered to encompass two major classes of surfactants, i.e. (a) alkylene oxide adducts of alkylphenols, and (b) alkylene oxide adducts of higher (greater than C 5 ) aliphatic alcohols or acids. Acids which can be utilized in the formation of the surfactant include lauric, myristic, oleic, linolenic, palmitic and stearic. Where the adduct of an aliphatic acid is used, may contain some unsaturation.
  • the surfactants contemplated for use in the invention are generally low foaming surfactants which do not significantly contribute to foam problems within the system.
  • the present invention also involves the use of a water soluble low molecular weight polyelectrolyte dispersants having the formula (II) given above, which covers any homo, co, ter, etc., polymer of the formula (II).
  • a water soluble low molecular weight polyelectrolyte dispersants having the formula (II) given above, which covers any homo, co, ter, etc., polymer of the formula (II).
  • An example of the carboxy-substituted alkyl group in formula (II) is -CH 2 COOH
  • an example of the deriative of a carboxy group in formula (11) is amide
  • an example of the hydrocarbon moiety commonly attached to free radical polymerizable monomers in formula (II) is -C 6 H 5 in styrene.
  • Examples of materials within the scope of the above formula (II) include polymaleic acid, polyacrylic acid, polymethacrylic acid, polyacrylic acid/itaconic acid copolymers, polyacrylic acid/hydrolyzed maleic acid copolymers, polymaleic acid/itaconic acid copolymers, hydrolyzed polymaleic acid/vinyl acetate copolymers, polyacrylic acid/acrylamide copolymers, polyacrylic acid/methacrylic acid copolymers, styrene/maleic acid copolymers, sulfonated styrene/maleic acid copolymers, polymaleic acid/methacrylic acid copolymers, maleic acid telomers, maleic/alkyl sulfonic copolymers.
  • a particularly preferred class of water soluble polyelectrolytes for use in the practices of the present invention is the polyacrylate compounds.
  • the polyacrylate compounds comprise polymers and copolymers of the structure: and their derivatives, wherein R 2 , R 5 , X, a and b are defined as above.
  • X is -COOZ, wherein Z is H, or a monovalent cation, e.g. Na + , K + , or NH4.
  • Z is H
  • a monovalent cation e.g. Na + , K + , or NH4.
  • typical of the preferred polyelectrolytes of the present invention are polyacrylic acid, polymethacrylic acid and copolymers of acrylic acid/methacrylic acid (e.g., AQUATREAT available from ALCO Chemical).
  • AQUATREAT available from ALCO Chemical
  • the words aquatreat and ALCO, and the words CELLOSOLVE and CARBITOL used below, are Registered Trade Marks.
  • the polyelectrolytes used in this invention must be water soluble.
  • the polymer must contain sufficient polar groups (e.g., COOH) for the molecule to interact with the polar water molecules.
  • polar groups e.g., COOH
  • unsaturated monomers which are predominantly or entirely hydrocarbon (e.g., styrene) there must be sufficient polar functional groups for the polymer to dissolve in room temperature or below water.
  • at least about 10 mole percent of the monomers comprising the polymer must contain polar functionality (e.g., to provide the required water solubility.
  • the low molecular weight polyelectrolytes used in present invention generally have molecular weights of less than about 50,000 with preferred molecular weights in the range of about 500 to 25,000, most preferably of 750 to 5,000. Thus, the sum of a + b above, generally falls in range of 5 to 1,000, preferably 10 to 500 and most preferably 12 to 450.
  • flocculants which may have molecular weights in the range of several million or more. Flocculants perform function of agglomerating suspended particles opposite the desired function of dispersion described herein. Thus, these high molecular weight materials operate in a manner effectively opposite that of the materials described herein.
  • the lower molecular weight materials of the present invention are generally referred to in the art as "dispersants".
  • the improvement of the present invention contemplates the use of various well-known water soluble solvents or cosolvents, along with the dispersants and surfactants.
  • the solvents unexpectedly provide increased removal of contaminants of the pulp.
  • the solvents can be ethoxylated solvents such as the glycol ethers available under the trademarks Cellosolve and Carbitol.
  • Preferred examples of solvents for use in this invention include tetrahydrofuran, tetrahydrofurfuryl alcohol, and ethoxylated and propoxylated derivatives thereof. It has been found that tetrahydrofurfuryl alcohol is particularly beneficial in the context of the invention, and it is theorized that this component contributes to the high recovery of pulp purity obtained by the method of this invention.
  • nonionic surfactant, dispersant, and solvent additives of the invention should be utilized in sufficient amounts of ratios to achieve increased recovery of cooking chemicals and soluble organics, and increased pulp purity after washing with a given volume of water.
  • the components produce the best results at a surfactant:dispersant ratio from about 0.5:1 to 2:1.
  • the desired concentration of the nonionic surfactants in the context of this invention is generally in the range of about 0.005 to 15 kg/metric ton (about 0.01 to 30 Ibs/short ton) oven dried pulp, with concentrations in the range of about 0.075 to 2.5 kg/metric ton (about 0.15 to 5 Ibs/short ton) being preferred.
  • concentrations of the polyelectrolyte dispersants should fall generally in the range of about 0.005 to 15 kg/metric ton (about 0.01 to 30 Ibs/short ton), or preferably 0.05 to 2 kg/metric ton (0.1 to 4 Ibs/short ton).
  • the concentration should fall in the range of about 0 to 12.5 kg/metric ton (about 0 to 25 Ibs/short ton), or more preferably 0.05 to 2 kg/metric ton (0.1 to 4 Ibs/short ton).
  • kg/metric ton or “pounds per short ton” refers to the weight of the additives in kilograms (or pounds), as compared to the weight in metric tons (or short tons) or oven dried pulp which is washed.
  • the additives can be supplied by various locations within the pulping system, such as any of the shower heads for the washers, the washer vats, the filtrate storage tank from where filtrate is recirculated through the washers, the digester, the deknotter, the repulper or the like.
  • the additives are distributed throughout the washing system particularly well when they are added to the shower head of an intermediate washer in a series of washers, such as the second in a series of three.
  • the additives can be added individually, or can be premixed and added as a mixture. Preferably, for reasons of conventicle and greater effectiveness, the additives are premixed.
  • a mixture of from 10 to 60% nonionic surfactant, 10 to 60% polyelectrolyte dispersant, and 0 to 50% solvent to total 100% is utilized at a level of from about 0.05 to 25 kg/metric ton (about 0.1 to 50.0 pounds per short ton) of pulp (oven dried) to be washed. More preferably the mixture will comprise from 30 to 50% nonionic surfactant, from 20 to 40% polyelectrolyte dispersant, and from 20 to 40% polyelectrolyte dispersant, and from 20 to 40% solvent to total 100%.
  • the concentration will range from 0.25 to 2.5 kg/metric ton (about 0.5 to 5.0 pounds per short ton), with the mixture being added in the shower head of an intermediate washer in a series of washers.
  • the temperature of the wash water can range from about 37.7 to 100°C (about 100 to 212°F), preferably in the range of about 60 to 82.2°C (about 140 to 180°F).
  • Example I was performed at a typical sulfite pulping mill having three rotary cylinder vacuum washers in sequence. Pre-trial, trial and post-trial production runs were monitored. The "pre-trial" data are taken from the mill during standard production, over a period of twenty-one days. The trial occurred over a twenty-seven day period wherein the invention was utilized at the mill under otherwise standard conditions. Post-trial data were taken during approximately twenty-one days following the end of the trial, again during standard production without use of the invention. The pre-trial and post-trial data are in the nature of a control, for comparison with the data obtained from use of the method of the invention.
  • the additive used during the trial was in all cases provided to the #2 shower. It comprised a mixture of 40% by weight of a modified alcohol ethoxylate with a specific gravity of 0.97, and an activity of 100%, 30 wt-% of a low molecular weight polyacrylic acid in the form of a 48 to 50% aqueous solution, having a pH at 100% of 1.5-2.0, and about 30 wt-% tetrahydrofurfuryl alcohol having a molecular weight of about 102, a specific gravity at 20/20°C of about 1.0543.
  • the temperature of the #2 shower solution ranged from 48.9-71.1°C (120°-160°F) during the trial.
  • the knotter TDS refers to the total dissolved solids in the liquid phase from the knotter, before washing of the pulp.
  • the #1 washer filtrate TDS refers to the total dissolved solids of the filtrate recovered from the first rotary cylinder vacuum washer in the series of three. A higher value indicates that a greater number of impurities have been washed from the pulp.
  • Number 3 washer mat TDS refers to the total dissolved solids of the mat itself which forms on washer #3. This is calculated by squeezing liquid from the mat, and testing that liquid for total dissolved solids. It is understood in the art that the composition of the liquid squeezings corresponds to the composition of the mat itself. A lower number indicates a more pure mat and is preferred.
  • Number 3 washer shower flow refers to the gallons per minute of wash water flowing from the head of shower number 3.
  • Red liquor solids refers to the weight percent of solids compared to the total weight of the red liquor. This value indicates the presence of impurities such as cooking chemicals, lignin and the like which the pump contains after digestion and which are removed during washing. A higher number indicates that more impurities have been removed from the pulp and will be recoverable.
  • Surge tank solids loss reflects the solids, whether cooking chemicals, lignin and the like, which are lost to recovery, that is, which have been carried over with the pulp and are therefore unrecovered. A lower value is preferred.
  • TDS refers to "total dissolved solids”.
  • the TDS #1 vat refers to the total dissolved solids of the brown stock in the vat of the first in the series of washers.
  • TDS #3 mat is a value obtained by analysis of the squeezings of the mat formed on the #3 washer.
  • TDS #3 shower reflects the total dissolved solids of the wash water sprayed through the #3 shower head.
  • Number 3 washer mat extractables is expressed as the weight percent of impurities as compared to the total weight of the mat. This test was performed following the TAPPI method but using a mixture of toluene and alcohol for the extraction process, rather than benzene and alcohol. A lower number indicates fewer organic soluble impurities in the pulp or mat.
  • N indicates the number of samples which were tested.
  • the values obtained were then analyzed via Student T test to provide the value given in Table 1.
  • S represents the standard of deviation among the values obtained.
  • the percentage given in parentheses indicates the confidence limits of the value.
  • Red Liquor solids increased during the trial and decreased the post-trial period.
  • the regression equation confirms a positive effect on red liquor solids equivalent to .19% per 0.5 kg/metric ton (1 pound/ short ton) of the additive mixture, or approximately 0.30% at the average trial feed rate of 0.75 kg/metric ton (1.5 pounds/short ton).
  • Results of the #1 washer filtrate total dissolved solids values indicate a significant increase, showing markedly better washing results with use of the additive mixture. Knotter total dissolved solids also increased during the trial.
  • the total dissolved solids in the #3 washer mat decreased 17% during the trial, compared to the pre-trial and post-trial average. This value indicates surprisingly effective solids removal.
  • the regression equation indicates that the effect of the additive mixture on #3 washer mat total dissolved solids is a decrease of .0615% when the additive mixture is used at 0.75 kg/metric ton (1.5 pound/short ton).
  • Number 3 washer mat extractables showed a 12% decrease during the trial versus post-trial period, an unexpectedly high decrease particularly in view of the high production rates during the trial.
  • Example II was performed as was Example I, in the same sulfite mill using the same standard procedures. The same additive was also used.
  • the first pre-trial lasted 8 consecutive days, followed later by an additional 12 day pre-trial period, where data were collected regarding the standard mill operation.
  • the trial period immediately followed the 12 day pre-trial, and lasted 5 days, while the post-trial period immediately followed the trial and lasted 3 days.
  • Dissolved solids in the #3 mat were decreased from an average of 0.49% to 0.42% during the trial, indicating a reduction of soluble inorganics and organics.
  • Water analysis of the #3 mat confirmed the significant reduction of inorganics during the trial.

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Claims (16)

1. Un procédé perfectionné pour éliminer les composés chimiques de cuisson usés ou en excès ou les contaminants organiques d'une pâte vierge préparée chimiquement ou mécaniquement, caractérisé en ce qu'il comprend (a) la formation d'une nappe de fibres de pâte vierge préparée chimiquement ou mécaniquement; et (b) le passage à force d'une solution aqueuse, comprenant un gent tensio-actif non ionique de type oxyéthylèneglycol substitué, un polyélectrolyte dispersant de bas poids moléculaire soluble dans l'eau et un solvant, dans et à travers la nappe de fibres, l'agent tensio-actif non ionique répondant à la formule:
Figure imgb0019
dans laquelle Ar est un résidu aromatique, a est zéro ou 1, R est un groupe aliphatique qui contient de 6 à 24 atomes de carbone lorsque a est zéro et de 6 à 18 atomes de carbone lorsque a est 1, n vaut de 3 à 50, m vaut de zéro à 50 et Y est un hydroxy ou un benzyléther, sous réserve que lorsque m est zéro, Y est un benzyléther, et où le polyélectrolyte dispersant a pour formule:
Figure imgb0020
dans laquelle R" R2, R4 et R5 sont indépendants et sont choisis parmi un hydrogène, un alcoyle inférieur en C,-C4, un alcoyle carboxy-substitué ou leurs mélanges, R3 et R6 sont indépendants et choisis parmi un hydrogène, un carboxy, un alcoyle carboxy-substitué ou leurs mélanges, X est choisi parmi un carboxy, les sels et dérivés d'un carboxy, un acétyle, des fragments hydrocarbures fixés ensemble à des monomères radicalaires, COOZ où Z est un ion de métal monovalent ou un ammonium, ou leurs mélanges, et le total de a + b se situe dans la gamme de 15 à 1 000.
2. Un procédé selon la revendication 1, dans lequel le passage à force de la soluble aqueuse dans et à travers la nappe de fibres comprend l'application de la solution aqueuse à la nappe et l'attraction de la solution dans et à travers la nappe avec une force créée par le vide.
3. Un procédé selon la revendication 2, dans lequel l'application de la solution aqueuse à la nappe comprend la pulvérisation de la solution aqueuse sur une surface de la nappe.
4. Un procédé selon l'une quelconque des revendications 1 à 3, dans lequel la nappe de fibres est formée à l'aide d'une pile laveuse aspirante à tambour rotatif.
5. Un procédé selon l'une quelconque des revendications 1 à 4, dans lequel la température de la solution aqueuse est de 37,7 à 100°C (100 à 212°F).
6. Un procédé de récupération des composés chimiques de cuisson en excès ou usés ou des contaminants organiques d'un milieu aqueux de fabrication de la pâte, comprenant de la pâte vierge préparée chimiquement ou mécaniquement et des composés chimiques en excès ou usés, ou des contaminants organiques, caractérisé en ce qu'il comprend (a) la combinaison du milieu aqueux de formation de la pâte avec un agent tensio-actif non ionique de type oxyéthylèneglycol substitué, un polyélectrolyte dispersant de bas moléculaire soluble dans l'eau et un solvant; (b) une séparation importante de la pâte vierge préparée chimiquement ou mécaniquement d'avec le milieu aqueux de formation de la pâte; et (c) après le stade (b), l'èlimination des composés chimiques de cuisson en excès ou usés ou des contaminants organiques du milieu aqueux de formation de la pâte; dans lequel l'agent tensio-actif non ionique répond à la formule:
Figure imgb0021
dans laquelle Ar est un résidu aromatique, a est zéro ou 1, R est un groupe aliphatique qui contient de 6 à 24 atomes de carbone lorsque a est zéro et de 6 à 18 atomes de carbone lorsque a est 1, n vaut de 3 à 50, m vaut de zéro à 50 et Y est un hydroxy ou un benzyléther, sous réserve que lorsque m est zéro, Y est un benzyléther, et où le polyélectrolyte dispersant a pour formule:
Figure imgb0022
dans laquelle Ri, R2, R4 et Rs sont indépendants et sont choisis parmi un hydrogène, un alcoyle inférieur en C,-C4, un alcoyle carboxy-substitué ou leurs mélanges, R3 et R6 sont indépendants et choisis parmi un hydrogène, un carboxy, un alcoyle carboxy-substitué ou leurs mélanges, X est choisi parmi un carboxy, les sels et dérivés d'un carboxy, un acétyle, des fragments hydrocarbures fixés ensemble à des monomères radicalaires, COOZ où Z est un ion de métal monovalent ou un ammonium, ou leurs mélanges, et le total de a + b se situe dans la gamme de 15 à 1 000.
7. Un procédé selon la revendication 6, dans lequel, dans la séparation importante de la pâte vierge préparée chimiquement ou mécaniquement d'avec le milieu aqueux de formation de la pâte, la pâte vierge préparée chimiquement ou mécaniquement est lavée dans un stade de lavage.
8. Un procédé selon la revendication 6 ou 7, dans lequel la pâte vierge préparée chimiquement ou mécaniquement est essentiellement séparée d'avec le milieu aqueux de formation de la pâte à l'aide d'une pile laveuse aspirante à cylindre rotatif.
9. Un procédé selon l'une quelconque des revendications 1 à 8, dans lequel le solvant est un solvant éthoxylé.
10. Un procédé selon la revendication 9, dans lequel le solvant comprend de l'alcool tétrahydro- furfurylique, un dérivé éthoxylé ou leurs mélanges.
11. Un procédé selon l'une quelconque des revendications 1 à 10, dans lequel l'agent tensio-actif non ionique de type oxyéthylèneglycol substitué, le polyélectrolyte dispersant de bas poids moléculaire soluble dans l'eau et le solvant réunis ont une concentration totale de 0,05 à 25 kg/t (0,1 à 5,0 Ib/short ton) de pâte séchée à l'étuve, la concentration totale étant constituée de 10 à 60% en poids d'agent tensio-actif, 10 à 60% en poids de dispersant et 20 à 50% en poids de solvant.
12. Un procédé selon la revendication 11, dans lequel la concentration totale est de 0,25 à 2,5 kg/t (0,5 à 5,0 Ib/short ton) de pâte séchée à l'étuve.
13. Un procédé selon l'une quelconque des revendications 1 à 12, dans lequel le polyélectrolyte dispersant comprend un copolymère d'acide maléique et d'acétate de vinyle.
14. Un procédé selon l'une quelconque des revendications 1 à 12, dans lequel le polyélectrolyte dispersant comprend un composé polyacrylate.
15. Un procédé selon la revendication 14, dans lequel le composé polyacrylate a un poids moléculaire dans la gamme de 500 à 25 000.
16. Un procédé selon l'une quelconque des revendications 1 à 12, dans lequel, dans la formule du polyélectrolyte dispersant, Ri, R3, R4 et R6 sont un hydrogène, R2 et Rs sont un hydrogène ou un méthyle et X est un carboxy.
EP19850302568 1984-09-19 1985-04-12 Méthode de lavage d'une pâte cellulosique Expired EP0177113B1 (fr)

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US65231184A 1984-09-19 1984-09-19
US652311 1984-09-19

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EP0177113B1 true EP0177113B1 (fr) 1989-07-19

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EP (1) EP0177113B1 (fr)
JP (1) JPH0672384B2 (fr)
BR (1) BR8501759A (fr)
CA (1) CA1252258A (fr)
DE (1) DE3571661D1 (fr)
FI (1) FI78517C (fr)
NO (1) NO167311C (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0709521A1 (fr) * 1994-10-26 1996-05-01 Betz Europe, Inc. Procédé pour augmenter la consistance de pâte à papier
DE19934607A1 (de) * 1999-07-23 2001-01-25 Basf Ag Hilfsmittel und Verfahren zur Reinigung und zum Bleichen von Zellulose-Pulpe
JP5374887B2 (ja) * 2008-02-27 2013-12-25 栗田工業株式会社 パルプ洗浄剤、及びパルプ製造方法
JP5181783B2 (ja) * 2008-03-31 2013-04-10 栗田工業株式会社 パルプ洗浄剤及びパルプ製造方法
CN103071771A (zh) * 2012-11-22 2013-05-01 河南省西保冶材集团有限公司 一种不锈钢专用连铸保护渣

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Publication number Priority date Publication date Assignee Title
US1730387A (en) * 1927-08-10 1929-10-08 Brown Co Processing of cellulose fiber
US2144756A (en) * 1937-10-14 1939-01-24 Nat Oil Prod Co Process of treating wood pulp to remove pitch
US3992249A (en) * 1974-04-08 1976-11-16 American Cyanamid Company Control of pulp-paper mill pitch deposits
US4184912A (en) * 1976-08-09 1980-01-22 Nalco Chemical Company Pitch control method
US4297164A (en) * 1980-03-10 1981-10-27 Weyerhaeuser Company Process for displacement washing of porous media
JPS591793A (ja) * 1982-06-28 1984-01-07 栗田工業株式会社 製紙用ピツチ付着防止剤

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FI851511L (fi) 1986-03-20
EP0177113A1 (fr) 1986-04-09
DE3571661D1 (en) 1989-08-24
JPS6175890A (ja) 1986-04-18
FI78517B (fi) 1989-04-28
FI851511A0 (fi) 1985-04-15
FI78517C (fi) 1989-08-10
NO167311B (no) 1991-07-15
NO167311C (no) 1991-10-23
BR8501759A (pt) 1986-04-22
NO851455L (no) 1986-03-20
CA1252258A (fr) 1989-04-11
JPH0672384B2 (ja) 1994-09-14

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