CN116635589A

CN116635589A - Method for improving efficiency of chemical additives in papermaking system

Info

Publication number: CN116635589A
Application number: CN202180083954.1A
Authority: CN
Inventors: D·E·萨洛扬; J·C·哈林顿·伊维; V·F·德·弗雷塔斯; F·H·G·B·德·奥利韦拉
Original assignee: Hercules LLC
Current assignee: Hercules LLC
Priority date: 2020-10-30
Filing date: 2021-10-29
Publication date: 2023-08-22
Also published as: MX2023005021A; KR20230093303A; AU2021369739A1; BR112023008253A2; CA3196967A1; CL2023001218A1; AU2021369739A9; WO2022094597A1; EP4237617A1

Abstract

The invention relates to a method for improving chemical efficiency of chemical additives in a papermaking system, which comprises the following steps: providing a concentrated pulp comprising soluble lignin, process water, and at least about 2% by weight cellulosic fibers based on the total weight of the concentrated pulp, and adding at least one organic polymer to the concentrated pulp to reduce the amount of soluble lignin therein. The organic polymer is selected from cationic polymers, nonionic polymers, and combinations thereof.

Description

Method for improving efficiency of chemical additives in papermaking system

Technical Field

The present disclosure relates to a method for improving the efficiency of chemical additives in papermaking systems. More specifically, the method manages the amount of soluble lignin in process water of pulping and papermaking systems by using specific polymers.

Background

There is a need for papermakers to maximize the efficiency of chemical additives in various systems, such as paper mills using virgin pulp, highly or fully enclosed recycled board mills, minimize fresh water consumption in pulping and papermaking, and minimize effluent emissions. There is also a need to improve pulping efficiency such as improving pulp yield, improving unbleached pulp washing efficiency, improving energy efficiency of black liquor evaporators, etc. Problems with reduced chemical efficiency of additives are common. The scarcity of fresh water resources and the increasing cost of fresh water use and effluent discharge have prompted papermakers to reduce fresh water consumption and recover process water. Today, many Recycling Linerboard (RLB) plants consume 5m per 1 ton of paper produced ³ Or less fresh water.

The amount of dissolved impurities in water can grow exponentially and cause many problems in papermaking. These problems include deposit formation, increased odor, and high levels of VFA, COD, and conductivity. An increase in the level of dissolved colloidal components can impair the effectiveness of chemical additives such as reinforcing, retention and drainage polymers, sizing agents, and the like. Thus, papermakers have to increase the consumption of chemical additives. However, at some point, the increase in polymer loading does not help to achieve the desired properties, especially in a fully closed paper mill.

The original paperboard plant consumes more fresh water than the recycled paperboard plant, but still suffers from the same problem of reduced chemical efficiency. In many virgin cardboard mills, chemical additives do not work well, and in some cases do not even work at all.

The efficiency of chemical additives such as retention and drainage polymers, dry strength agents, sizing agents, and wastewater treatment polymers may increase with the removal of anionic trash, and more particularly, with the removal of soluble lignin materials.

In addition to cellulose and hemicellulose, lignin is also one of the main components of wood. Lignin is a natural, highly aromatic and hydrophobic polymer. For the production of print grade paper, most lignin is disintegrated and removed from cellulose by Kraft pulping. The additional amount of lignin is further reduced by a series of bleaching and washing stages. However, for the production of packaging grade paper, other pulp sources are used. These pulp sources include virgin pulp, mechanical pulp, semi-chemical mechanical pulp, and recycled fibers such as OCC (old corrugated container, old corrugated containers) and the like. These grades of pulp may include significant amounts of lignin.

The prior art describes several compositions or applications for improving the quality of lignocellulosic paper. The prior art deals with residual lignin and/or other contaminants present in or on the surface of the fibers. However, the prior art does not address the problem of soluble lignin in process water and the impact of process water containing large amounts of soluble lignin on the papermaking process. If the quality of the process water is compromised, chemical additive efficiency is compromised whether contaminants are present in the fibers or not.

Furthermore, the presence of soluble lignin fragments in process water is quite problematic due to the accumulation of large amounts of low molecular weight lignin material. The smaller soluble lignin fragments present in the plant process water do not have sufficient affinity for the cellulose fibers and therefore continue to circulate in the plant water system. Thus, there remains an opportunity for improvement.

Disclosure of Invention

The present disclosure solves the problem of soluble colloidal lignin dissolved in plant process water via a polymerization process. More specifically, the present disclosure provides a method of improving the chemical efficiency of chemical additives in papermaking systems. The method comprises the following steps: providing a concentrated pulp comprising soluble lignin, process water, and at least about 2% by weight cellulosic fibers based on the total weight of the concentrated pulp, and adding at least one organic polymer to the concentrated pulp to reduce the amount of soluble lignin therein. In addition, the organic polymer is selected from cationic polymers, nonionic polymers, and combinations thereof.

The present disclosure also provides another method of increasing the chemical efficiency of a chemical additive in a papermaking system. The method comprises the following steps: providing a concentrated pulp comprising soluble lignin, process water, and at least about 2% by weight cellulosic fibers based on the total weight of the concentrated pulp, and adding at least one inorganic coagulant to the concentrated pulp to reduce the amount of soluble lignin therein.

Drawings

The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, an

FIG. 1 is Table 1 referred to in the examples, showing the variation of ABS, lignin (ppm) and lignin reduction (%) with treatment type;

FIG. 2A is Table 2 referred to in the examples, showing lignin (ppm) in water as a function of treatment type and number of treatments;

fig. 2B is a bar graph as mentioned in the examples, showing lignin reduction (%) as a function of treatment type;

FIG. 3 is Table 3 mentioned in the examples, showing the changes in ABS, lignin (ppm), lignin reduction (%), COD (ppm) and COD reduction (%) with treatment type;

FIG. 4A is Table 4 mentioned in the examples, showing the change in drainage improvement (%) with thick and thin slurry treatment and polymer treatment;

FIG. 4B is a bar graph as referred to in the examples, showing the change in drainage in seconds with treatment;

FIG. 4C is a bar graph as referred to in the examples, showing the change in drainage polymer efficiency improvement (%) with treatment;

FIG. 5A is a table as referred to in the examples showing lignin (ppm), lignin reduction (%), mutek charge and reduction (%) as a function of treatment;

FIG. 5B is a graph as referred to in the examples, showing lignin reduction as a function of measurement date;

FIG. 6A is Table 6A mentioned in the examples, showing lignin (ppm), lignin reduction (%), turbidity and turbidity reduction (%) as a function of treatment type;

FIG. 6B is a graph as referred to in the examples, showing lignin reduction as a function of measurement date;

FIG. 6C is a graph as referred to in the examples, showing the change in the amount of the resin control agent with the date of measurement;

FIG. 6D is a graph as referred to in the examples, showing the change in sizing agent dosage with the date of measurement; and

fig. 6E is table 6E mentioned in the examples, showing various properties measured before and after various experimental trials.

Detailed Description

A method of removing soluble lignin in a papermaking system is disclosed. The method may increase the chemical efficiency of papermaking additives including reinforcing additives, retention and drainage polymers, sizing agents, and others. In addition, the new method improves the pulping section and reduces the water used in the unbleached pulp wash. A method for removing soluble lignin from a concentrated pulp during a papermaking process is disclosed. The method includes adding a cationic or nonionic polymer to the concentrated pulp. The method may further comprise adding a cationic or nonionic polymer and/or an inorganic coagulant to the concentrated pulp of the papermaking system in a highly closed papermaking system. The reduction of lignin in the concentrated pulp and its fixation to the fibers results in a significant increase in the efficiency of those chemical additives including reinforcing agents, sizing agents, retention aids and drainage agents. In various embodiments, the concentrated pulp comprises less than about 5, 4, 3, 2, 1, 0.5, or 0.1 wt.% enzyme, or is completely free of enzymes, such as laccase or any other enzyme known in the art. Alternatively, the concentrated pulp may comprise any enzyme known in the art in the amounts described above. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

The reduction of lignin in the thick stock and its fixation to the fibres may also lead to an improvement of the pulping section. These improvements may result from a reduction in the amount of water used in the washing of the non-rinsed pulp. These improvements also include more efficient pulp washing, improved black liquor evaporator efficiency, improved pulping efficiency, and improved pulp yield.

As the degree of water containment increases, chemical additive efficiency decreases, either due to regulatory limitations or water scarcity. The decrease in chemical efficiency and in some cases the complete loss of polymer additive performance is often due to organic contaminants, i.e. non-strictly defined substances in the plant process water commonly referred to as anionic trash. Anionic trash typically includes very short fibers called fines, degraded starch, degraded or modified chemical additives such as polymers, and dissolved soluble colloidal lignin. These components have different effects on the properties of chemical additives, in particular cationic polymers. Using the white water system model, applicants investigated the effect of several problematic components on cationic polymers based on component analysis at several industrial recovery paper mills. Lignin, while not the most common substance in plant process water, has the greatest adverse effect on chemical efficiency.

Lignin levels in process water in highly closed recycled paper plants may accumulate. Because of inadequate pulp washing, they can also be very high in relatively open virgin paper plants. In either case, the lignin content may be high enough to completely or partially deactivate the polymer additive and impair its performance.

The present disclosure solves the problem of soluble lignin in concentrated pulp via a polymerization process. Soluble lignin may be removed from papermaking process water by a treatment comprising adding nonionic and/or cationic polymers to the concentrated pulp. As used herein, the term dried supply solids (dried solid) may alternatively be described as dried cellulosic fibers.

Nonionic polymers useful in the present disclosure include, but are not limited to, polyoxazolines, polyethylene oxide (PEO), copolymers of polyethylene oxide or Polypropylene Oxide (PO), copolymers of polyethylene oxide and polypropylene oxide (EO/PO), polyvinylpyrrolidone, polyethylenimine (PEI), and/or combinations thereof. The PEO may be a homopolymer of ethylene oxide, or a copolymer of ethylene oxide with propylene oxide and/or butylene oxide. Homopolymers of polyethylene oxide are most typical. Examples of such products are available as dry powder products from Solenis LLC (Wilmington, DE) as form PB 8714 and from Dow Chemical (Midland, mich.) as Ucarfloc 300, 302, 304 and 309. PEO homopolymers are also available as slurries in which PEO is dispersed in a medium. The medium may be any one or more of ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin, and the like, and/or combinations thereof. Examples of PEO slurries include Zalta MF 3000 from Solenis LLC (Wilmington, DE).

The nonionic or cationic polymers useful in the present disclosure may have the formula I or II or III:

b represents one or more different nonionic repeating units formed after polymerization of one or more nonionic monomers.

C represents one or more different cationic repeat units formed after polymerization of one or more cationic monomers.

The nonionic polymer segments B in formulas I and II are repeating units formed after polymerization of one or more nonionic monomers. Exemplary monomers contemplated by B that can be used in the present disclosure include, but are not limited to: an acrylamide; methacrylamide; n-alkyl acrylamides, such as N-methyl acrylamide; n, N-dialkylacrylamides, such as N, N-dimethylacrylamide; methyl methacrylate; methyl acrylate; acrylonitrile; n-vinylmethylacetamide; n-vinylformamide; n-vinylmethylformamide; vinyl acetate; n-vinylpyrrolidone and mixtures of any of the foregoing. The present disclosure contemplates that other types of nonionic monomers may be used, or that more than one nonionic monomer may be used. The nonionic monomer preferably used is acrylamide; methacrylamide, N-vinylformamide.

The cationic polymer segment C in formulas II and III is a repeating unit formed after polymerization of one or more cationic monomers. Exemplary monomers contemplated by C that can be used in the present disclosure include, but are not limited to: cationic ethylenically unsaturated monomers such as diallyldialkylammonium halides (such as diallyldimethylammonium chloride); (meth) acrylic esters of dialkylaminoalkyl compounds such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, 2-hydroxydimethylaminopropyl (meth) acrylate, aminoethyl (meth) acrylate, and salts and quaternary ammonium salts thereof; n, N-dialkylaminoalkyl (meth) acrylamides, such as N, N-dimethylaminoethyl acrylamide, and salts and quaternary ammonium salts thereof, and mixtures thereof. Most typical are diallyldimethylammonium chloride (DADMAC) and dimethylaminopropyl (meth) acrylamide (DIMAPA), dimethylaminoethyl (meth) acrylate (ADAME) and salts and quaternary ammonium salts thereof and mixtures of the foregoing.

Another method of producing cationic polymers having structure II is by polymerization of monomers followed by hydrolysis. The hydrolysis level may be expressed as "% hydrolysis" or "% hydrolysis" on a molar basis. Thus, hydrolyzed polymers can be described as "% hydrolyzed". Furthermore, the hydrolysis level can be estimated. For the purposes of applicants' disclosure, poly (vinylamine) referred to as "50% hydrolyzed" refers to about 40 to about 60% hydrolyzed. Likewise, about 100% hydrolyzed poly (vinylamine) means about 80 to about 100% hydrolyzed. The hydrolysis reaction results in the conversion of some or all of the monomer to amine, as controlling the hydrolysis reaction can alter the percentage of the resulting monomer having amine functionality. Poly (vinylamine) can be used in the present disclosure. Examples of monomers for preparing poly (vinylamine) include, but are not limited to: n-vinylformamide, N-vinylmethylformamide, N-vinylphthalimide, N-vinylsuccinimide, tert-butyl N-vinylcarbamate, N-vinylacetamide and mixtures of any of the foregoing. Most typically are polymers prepared by hydrolysis of N-vinylformamide. In the case of copolymers, nonionic monomers such as those described above are typical comonomers. Alternatively, poly (vinylamine) can be prepared by derivatization of the polymer. Examples of such a process include, but are not limited to, the Hofmann reaction of polyacrylamide. It is contemplated that other routes of synthesizing poly (vinylamine) or polyamines may be used.

Polymer dispersions as described in us patent 7323510, which is expressly incorporated by reference in various non-limiting embodiments herein, can be used in the present disclosure. For example, a dispersion comprising (i) a high molecular weight cationic polyacrylamide having a weight average molecular weight greater than about 1,000,000, and (ii) a high charge (derived from greater than about 50%, typically about 60%, cationic monomer), low molecular weight cationic dispersant polymer having a molecular weight between about 100,000 and about 500,000 may be used in the present disclosure. Typical cationic monomers for the components of the dispersion are those listed for polymer segment C. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

B of nonionic monomer and cationic monomer of formula II: the mole percent of C may fall within the range of about 99:1 to about 1:99, or about 80:20 to about 20:80, or about 75:25 to about 25:75, or about 40:60 to about 60:40, or about 99:1 to 50:50, and most typically about 99:1 to about 90:10, where the mole percentages of B and C add up to about 100%. It is understood that more than one nonionic or cationic monomer may be present in formulas II or III. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

The cationic or nonionic polymers used in the present disclosure may be manufactured and supplied to the end user as dry or granular powders, aqueous solutions, dispersions or inverse emulsions.

The molecular weight of the cationic or nonionic polymer can be from about 100,000 to about 1,000 kilodaltons, typically greater than about 250,000. The cationic or nonionic polymer can have a molecular weight of about 400,000 to about 1,000 kilodaltons. Generally higher molecular weight nonionic polymers are more effective in removing soluble lignin. For example, when nonionic or dispersion polymers are used, typical molecular weights are about 100 tens of thousands or greater. For highly charged (greater than 60% cationic monomer) cationic polymers (DADMAC or DIMAPA or EPI-DMA), the molecular weight may be from about 100,000 up to about 1,000,000, or typically from about 200,000 up to about 500,000. Typically for low charge cationic polymers (10 mole% cationic monomer or less), the molecular weight can be from about 1,000,000 up to about 10,000,000 daltons. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

The nonionic or cationic polymer can be used in an amount of from 0.01 to 10 pounds of polymer solids per ton of dried pulp (e.g., dry slurried solids), or from about 0.01 to about 10, or from about 0.05 to about 5, or from about 0.1 to about 3 pounds, or from about 0.1 to about 2 pounds of polymer solids (e.g., reactive organic polymer) per ton of dried pulp (e.g., dry slurried solids). In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

Removal of soluble lignin is further improved by combining a nonionic or cationic polymer with an added inorganic cationic coagulant like polyaluminum chloride, alum (aluminum sulfate), aluminum chlorosulfate, aluminum chlorohydrate, iron (III) chloride, iron (III) sulfate, iron (II) chloride, iron (II) sulfate, iron (II) polysulfate, any other aluminum or iron based cationic coagulant known to those skilled in the art. The inorganic cationic coagulant may be added in an amount of about 0.01 to about 12 pounds of dry solids per ton of dry fiber solids, or more specifically, about 0.05 to about 6 pounds of dry solids per ton of dry fiber solids. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

The reduction of soluble lignin is accompanied by a reduction of negative Mutek charges of laboratory produced water or paper mill process water. The Mutek charge is defined as the surface charge of the colloidal material in the filtrate. Since soluble lignin is one of the important contributors to negative Mutek charge, it is expected that a reduction in soluble lignin will reduce the negative Mutek charge of process water by at least about-50 μequ/L, possibly by about-100 μequ/L, or by about-200 μequ/L or more.

Reduction of soluble lignin in the pulp concentrate by polymer or polymer combination treatment results in improved chemical efficiency. These include, but are not limited to, the efficiency of retention and drainage polymers, enhancers, sizing agents, and the like.

Since substances which are difficult to oxidize and remove by the traditional water body restoration method are removed, the reduction of the soluble lignin in the concentrated paper pulp is expected to be beneficial to not only improving the chemical efficiency, but also the operation of a primary clarifier, an anaerobic and aerobic digester workshop (plant) and the comprehensive treatment of wastewater. The removal of soluble lignin and the increase in chemical efficiency are also expected to reduce fresh water usage and increase in water blocking.

Removal of soluble lignin is expected to reduce the COD (chemical oxygen demand) of process water and the COD of wastewater streams, including COD fractions that are more difficult to oxidize (or epoxy) and typically require tertiary treatment with oxidants. This in turn is expected to make wastewater treatment more efficient and less costly.

The polymer may be applied to the thick stock or portions of the paper making where the process water is mixed with the cellulosic fibers, i.e., in a thin stock and/or thick stock. The polymer may also be added to the slurry where the concentrate is mixed with the process white water at the primary fan pump. The location of the polymer addition to the slurry may include, but is not limited to, a primary or secondary fan pump, the inlet or discharge side of the cleaner, or the inlet or discharge of a pressure screen.

However, the best efficiency is achieved by applying the polymer product or combination of polymer products directly to a thick stock, such as a blend stock tank, a machine stock tank (machine stock). A concentrated pulp may be defined as a mixture of process water and cellulosic fibers, wherein the fiber consistency is about 2% or higher, such as about 2 to about 3, about 3 to about 4, about 2 to about 4, or about 4%. The application of the polymer to the thick stock ensures that the soluble lignin is removed onto the fibers and thus into the finished paper. A thin pulp may be defined as a mixture of process water and cellulosic fibers, wherein the fiber consistency is less than about 2%, 1.5%, 1% or 0.5%. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

The proposed treatment methods are found to be advantageous for the efficiency of the polymer additives both in RLB paper mills where OCC is mainly used and in virgin paper mills where Unbleached Kraft Pulp (UKP), semi-chemimechanical pulp like neutral sulfite semi-chemimechanical pulp (NSSC), combined recovery and virgin pulp (e.g. NSSC/OCC), also deinked pulp (DIP), mechanical pulp like thermo-mechanical pulp (TMP), recovery newspapers, recovery tissues or other fiber sources are used.

Also provided is a method of increasing the efficiency of a chemical additive in a papermaking system comprising adding at least one polymer and at least one inorganic coagulant to a concentrated pulp to reduce the amount of soluble lignin in the concentrated pulp.

In various embodiments, the method may provide additional benefits to the pulping section of the papermaking process, but the pulping section precedes the treatment of soluble lignin in the paper machine and the proposed thick stock. This is because effective lignin management can use less condensate and/or fresh water in the unbleached pulp wash, thus reducing the use of condensate and/or fresh water. Furthermore, the method may result in a higher solids content in the black liquor from the washing process.

The reduced volume of black liquor also reduces the energy consumption of the black liquor evaporator due to the higher content of organic and inorganic solids in the black liquor and the lower water usage in the unbleached pulp wash. Black liquor evaporation is an energy intensive process. In this process, black liquor is concentrated from about 15% solids to about 70% or more by several black liquor evaporators, in which water is progressively removed by evaporation to steam. Even if the solid percentage of the original black liquor is slightly increased, the energy can be saved remarkably.

Alternatively, the method may also help to produce more pulp and/or result in increased number of digestions or increased digestion efficiency, as unbleached pulp washing becomes more efficient by lignin fixation and removal in the paper mill. For example, the pulp yield increase may be from about 1% to about 2%, from about 3% to about 4%, from about 4% to about 6%, from about 7% to about 8%, from about 9 to about 10% or more, or from about 1 to about 10, from about 2 to about 9, from about 3 to about 8, from about 4 to about 7, or from about 5 to about 6%, depending on the needs of pulping and papermaking. Due to the efficient lignin management, the pulp mill section may play a greater role in cooking the pulp to reduce Kappa values.

In various embodiments, the present disclosure describes the use of polymer(s) in a thick stock of a papermaking process, such as in a blend chest, a papermachine chest, or a headbox, or via simultaneous application at different points in the papermaking process. However, the method may also be beneficial in applying one or more lignin-fixing polymers or polymers in an alternative section to the paper or pulp section. These applications may include applying the lignin-fixing polymer to the final stage of unbleached pulp washing, such as Drum Displacement (DD) washing, or to the final stage of a bleaching plant, such as after the extraction stage, or before or after the dewatering stage, or in the slurry of the papermaking process.

In the bleaching plant, after the pulp has been bleached and washed, it is dewatered (using a dewatering machine) and typically stored in a high density (HiD) storage tank until it is needed by the paper mill. If the lignin fixing and removing polymer is added after washing but before dewatering in a dewatering machine, it may be beneficial to apply the lignin fixing and removing polymer, since most impurities are removed with the washing water at this time. Lignin fixation and polymer removal after thickening of the pulp is also possible, but the contact time may be significantly longer.

If a bleaching stage is not used, a storage tank of unbleached pulp after washing and dewatering of unbleached pulp may be used as a location for adding polymer(s) to fix and remove lignin. Alternatively, the polymer(s) may be added to the last stage of the unbleached pulp wash. The method may also allow for the use of less water or shorter washing time (or both) in the unbleached pulp wash, generally allowing for increased pulp throughput.

Other embodiments:

in various embodiments, this provides a method of improving the chemical efficiency of chemical additives in a papermaking system. The method also provides improvements in the following manner: the pulp production efficiency is improved in the pulp making section, the pulp washing efficiency and black liquor recirculation during combustion in the boiler are improved, and the steam production is improved. The method comprises the following steps: providing a concentrated pulp comprising soluble lignin, process water, and at least about 2% by weight cellulosic fibers based on the total weight of the concentrated pulp, and adding at least one organic polymer to the concentrated pulp to reduce the amount of soluble lignin therein. In addition, the organic polymer is selected from cationic polymers, nonionic polymers, and combinations thereof. The method also provides an additional method of increasing the chemical efficiency of chemical additives in a papermaking system. The method comprises the following steps: providing a concentrated pulp comprising soluble lignin, process water, and at least about 2% by weight cellulosic fibers based on the total weight of the concentrated pulp, and adding at least one polymer and at least one inorganic coagulant to the concentrated pulp to reduce the amount of soluble lignin therein.

In one embodiment, the organic polymer is cationic. In another embodiment, the cationic polymer has the general formula II: [ B co C- ], wherein B represents one or more different nonionic repeating units formed after polymerization of one or more nonionic monomers, and C represents one or more different cationic repeating units formed after polymerization of one or more cationic monomers. In another embodiment, the nonionic monomer of formula II is with B of the cationic monomer: the mole percent of C is about 99:1 to about 1:99, or about 80:20 to about 20:80, or about 75:25 to about 25:75, or about 40:60 to about 60:40, or about 99:1 to about 50:50. In a further embodiment, the mole percent of B to C of the nonionic monomer to cationic monomer of formula II is from about 99:1 to about 90:10. In yet another embodiment, the organic polymer has the general formula II: [ C- ], wherein C represents one or more different cationic repeat units formed after polymerization of one or more cationic monomers. In a further embodiment, the cationic or nonionic polymer is selected from the group consisting of cationic polyacrylamides, polyvinyl amines, polyethylenimines, diallyldimethyl ammonium chloride polymers, trialkylaminoalkyl (meth) acrylamide polymers, epichlorohydrin-dimethylamine copolymers, polyethylene oxide polymers, polyethylene oxide/polypropylene oxide copolymers, polyoxazolines, and combinations thereof. Alternatively, the cationic polyacrylamide is derived from at least one monomer selected from the group consisting of: diallyldimethylammonium chloride, N, N, N-trialkylaminoalkyl (meth) acrylate, N, N, N-trialkylaminoalkyl (meth) acrylamide, epichlorohydrin-dimethylamine, and combinations thereof. Further, the cationic polymer may comprise a polyvinylamine, wherein the polyvinylamine is derived from at least one monomer selected from the group consisting of: n-vinylformamide, N-vinylmethylformamide, N-vinylphthalimide, N-vinylsuccinimide, tert-butyl N-vinylcarbamate, N-vinylacetamide, and mixtures of any of the foregoing, wherein typically at least one monomer is N-vinylformamide. In another embodiment, the cationic polymer is a polymer dispersion comprising (i) a high molecular weight cationic polyacrylamide and (ii) a low molecular weight highly variable cationic dispersant polymer. In yet another embodiment, the nonionic or cationic polymer has a weight average molecular weight of from about 100,000 to about 1,000 kilodaltons and typically from about 400,000 to about 1,000 kilodaltons. Alternatively, the organic polymer is nonionic. Further, the nonionic polymer can have a weight average molecular weight of about 400,000 to about 1,000 kilodaltons and typically about 1,000,000 to about 10,000,000 daltons. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

In other embodiments, the present disclosure provides a method of increasing the efficiency of a chemical additive in a papermaking system comprising adding at least one organic polymer to a concentrated pulp to reduce the amount of soluble lignin in the concentrated pulp; wherein the organic polymer comprises a polyethylene oxide polymer having a weight average MW greater than about 1,000,000 and less than about 1,000 kilodaltons. Alternatively, the present disclosure provides a method of improving the efficiency of a chemical additive in a papermaking system comprising adding at least one organic polymer to a concentrated pulp to reduce the amount of soluble lignin in the concentrated pulp; wherein the organic polymer comprises a cationic polyacrylamide having a weight average MW of greater than about 200,000 and less than about 1,000 kilodaltons. In other embodiments, the organic polymer is added to the concentrated pulp in an amount of from 0.01 pounds to 10 pounds per ton of dried pulp (e.g., dry ingredients solids), or from about 0.01 to about 10, or from about 0.05 to about 5, or from about 0.1 to about 3 pounds of polymer solids (e.g., active organic polymer) per ton of dried pulp (e.g., dry ingredients solids). In still other embodiments, the at least one organic polymer is added to a concentrated pulp, wherein the concentrated pulp may be a slurry of process water and cellulosic fibers having a consistency of about 2% or more. Alternatively, the at least one organic polymer and at least one inorganic coagulant are added to a thick pulp, which may be defined as a slurry of process water and cellulosic fibers having a consistency of about 2% or more, simultaneously or in parallel. In a further embodiment, the organic polymer comprises a homopolymer. Alternatively, the organic polymer comprises a copolymer. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

In other embodiments, the removal of soluble lignin is monitored by a decrease in absorbance at about 280nm in the UV-VIS spectrum, and the absorbance is reduced by about 5% after about 24 hours as compared to the system prior to adding laccase and cationic or nonionic polymer to the concentrated slurry. Alternatively, the concentrated pulp comprises a cellulosic fiber source, wherein the cellulosic fiber source is selected from OCC, deinked pulp, virgin fiber, mechanical pulp, unbleached Kraft pulp, or mixtures thereof. Still further, the concentrated pulp may include a source of cellulosic fibers, wherein the source of cellulosic fibers includes recycled paper. In other embodiments, the at least one chemical additive in the papermaking system is selected from retention and drainage polymers, reinforcing agents, and sizing agents, and combinations thereof. In still further embodiments, the COD in the process water or wastewater stream is reduced by at least about 5% as compared to the COD of the system prior to adding the cationic or nonionic polymer or polymer combination to the concentrate. Still further, the method may further comprise adding an inorganic coagulant to the thick stock. In other embodiments, the inorganic coagulant is selected from the group consisting of aluminum sulfate, aluminum chloride, aluminum chlorohydrate, polyaluminum chloride, polyaluminum sulfate, iron (III) chloride, iron (III) sulfate, iron (II) chloride, iron (II) sulfate, iron (II) polysulfate, and combinations thereof. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

The present disclosure also provides a method comprising the steps of: providing a concentrated pulp comprising soluble lignin, process water and at least about 2% by weight of cellulosic fibers based on the total weight of the concentrated pulp, and adding the at least one organic polymer and at least one inorganic coagulant to the concentrated pulp to reduce the amount of soluble lignin therein. In other embodiments, the inorganic cationic coagulant is added to the papermaking system in an amount of from about 0.01 to about 12 pounds of dry solids per ton of dry fiber solids or more specifically from about 0.05 to about 6 pounds of dry solids per ton of dry fiber solids. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

In various embodiments, the present disclosure provides a method of increasing the efficiency of a chemical additive in a papermaking system, wherein the method comprises the steps of: providing a concentrated pulp comprising soluble lignin, process water, and at least about 2% by weight cellulosic fibers based on the total weight of the concentrated pulp, and adding at least one organic polymer to the concentrated pulp to reduce the amount of soluble lignin therein. In addition, the organic polymer is selected from cationic polymers, nonionic polymers, and combinations thereof. In another embodiment, the concentrated pulp comprises at least about 3 or 4% by weight cellulosic fibers based on the total weight of the process water. In such embodiments, the cellulosic fibers are derived from NSSC pulp, OCC pulp, deinked pulp, virgin fiber, mechanical pulp, unbleached Kraft pulp, or a combination thereof. In a further embodiment, the organic polymer is cationic and has the general formula II: [ B-co-C ] (II) wherein B is one or more nonionic repeating units formed after polymerization of one or more nonionic monomers, C is one or more different cationic repeating units formed after polymerization of one or more cationic monomers, and-co-means that the polymer is a copolymer of B and C. In another embodiment, the mole percent of B to C of the nonionic monomer to cationic monomer of formula II is from about 75:25 to about 25:75. In yet another embodiment, the organic polymer has the general formula III: [ -C- ] wherein C is one or more different cationic repeat units formed after polymerization of one or more cationic monomers. In a further embodiment, the organic polymer is selected from the group consisting of cationic polyacrylamides, polyvinyl amines, polyethylenimines, diallyldimethyl ammonium chloride polymers, trialkylaminoalkyl (meth) acrylamide polymers, epichlorohydrin-dimethylamine copolymers, polyethylene oxide polymers, polyethylene oxide-polypropylene oxide copolymers, polyoxazolines, and combinations thereof. In yet a further embodiment, the cationic polyacrylamide is derived from at least one monomer selected from the group consisting of: diallyldimethylammonium chloride, N, N, N-trialkylaminoalkyl (meth) acrylate, N, N, N-trialkylaminoalkyl (meth) acrylamide, epichlorohydrin-dimethylamine, and combinations thereof. In another embodiment, the cationic polymer comprises a polyvinylamine derived from at least one monomer selected from the group consisting of: n-vinylformamide, N-vinylmethylformamide, N-vinylphthalimide, N-vinylsuccinimide, t-butyl N-vinylcarbamate, N-vinylacetamide, and combinations thereof. In yet another embodiment, the organic polymer is a polymer dispersion comprising (i) a high molecular weight cationic polyacrylamide having a weight average molecular weight of greater than about 1,000,000g/mol and (ii) a low molecular weight cationic dispersant polymer derived from greater than about 50 weight percent cationic monomer and having a weight average molecular weight of from about 100,000 to about 500,000 g/mol. In an additional embodiment, the nonionic or cationic polymer has a weight average molecular weight of about 100,000 to about 1,000 kilodaltons. In another embodiment, the organic polymer is nonionic and has a weight average molecular weight of from about 1,000,000 to about 10,000,000 daltons. In another embodiment, the organic polymer is a polyethylene oxide polymer having a weight average molecular weight greater than about 1,000,000 and less than about 1,000 kilodaltons. In a further embodiment, the organic polymer is a cationic polyacrylamide having a weight average molecular weight of greater than about 200,000 and less than about 1,000 kilodaltons. In another embodiment, the organic polymer is added to the concentrated pulp in an amount of about 0.05 to about 5 pounds of organic polymer (e.g., active organic polymer) per ton of dry pulping solids, i.e., oven dried cellulose fibers. In a further embodiment, the reduction in the amount of soluble lignin in the concentrated pulp is demonstrated by: the absorbance in the UV-VIS spectrum measured after 24 hours at about 280nm is reduced by at least 5% as compared to process water without the at least one organic polymer. In another embodiment, the chemical oxygen demand of the process water is reduced by at least about 5% as compared to the chemical oxygen demand of process water without the at least one organic polymer. In a further embodiment, the method comprises the step of adding an inorganic coagulant to the concentrated pulp, wherein the inorganic coagulant is selected from the group consisting of aluminum sulfate, aluminum chloride, aluminum chlorohydrate, polyaluminum chloride, polyaluminum sulfate, iron (III) chloride, iron (III) sulfate, iron (II) chloride, iron (II) sulfate, iron (II) polysulfate, and combinations thereof. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

The present disclosure also provides a method of achieving improved pulping section, such as improved pulping yield and efficiency, improved black liquor evaporator and reduced energy, reduced water in unbleached pulp wash, and the like. These improvements are achieved by the following methods: providing a concentrated pulp comprising: the method includes the steps of adding soluble lignin, process water, and at least about 2 wt% cellulosic fibers based on the total weight of the concentrated pulp, and adding at least one organic polymer to the concentrated pulp to reduce the amount of soluble lignin therein. In addition, the organic polymer is selected from cationic polymers, nonionic polymers, and combinations thereof.

In other embodiments, the method further comprises the steps of: providing a thin pulp and adding the at least one organic polymer to the thin pulp at the same time as the step of adding the at least one organic polymer to the thick pulp.

In further embodiments, the methods of the present disclosure increase pulp yield by at least about 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10% (or more), measured in tons of pulp produced per day. For example, because the process is more efficient than other processes, additional pulp may be produced at the front end of the process, i.e., prior to the step of providing the concentrated pulp. An increase in pulp yield can be determined as compared to a control method without the use of the at least one organic polymer of the present disclosure. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

In other embodiments, the method further comprises the step of providing black liquor having a solids percentage at least 0.5% greater than a control method that does not use the at least one organic polymer. In other words, the present disclosure allows for the use of "dirtier" solutions. In various embodiments, black liquor useful in this process can have a solids percentage at least about 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5% (or even higher) higher than a control process that does not use the at least one organic polymer. This increase in solids content means that a dirtier black liquor stream can be used. This reduces production time, complexity and cost. In various non-limiting embodiments, all values and ranges of values including and between those described above are hereby expressly contemplated herein.

Examples

The polymer products used in this test were product a (aqueous cationic polyacrylamide dispersion, 28% active) and product B (25% active, polyethylene oxide dispersion product), product C (40% active, polydiallyl dimethyl ammonium chloride (polydadmac) based product), product D (24% active polyethylenimine), product E (13% active, anionic acrylamide), product F (20% active, amphoteric acrylamide) and product G (aqueous cationic polyacrylamide dispersion, 33% active), all being products of solatis LLC. The level of polymer addition is given in pounds (or kilograms) of active polymer per ton of dry paper. In a laboratory setting, the polymer product was first dissolved in water to make a 2,500ppm solution, and then added to the process water or slurry.

The test was performed using a thick stock (OCC, UKP, TMP) from each blend chest of the paper machine and having a consistency of 3.6 to 4% and the white water or synthetic furnish collected by the headbox was made by mixing the cellulosic fibers with synthetic white water. The pH of the thick stock and white water samples varied from 6.0 to 7.5.

The synthetic white water used for the test was made by adding several inorganic components (calcium chloride, sodium sulfate and sodium acetate) and organic components (anionic starch, soluble lignin, sodium polyacrylate, sodium oleate, acetic acid and galacturonic acid). The resulting mixture had a conductivity of 4,700 to 5,000uS/cm and a pH of 6.1 to 6.5. Experiments were performed on a 250 or 500g scale with moderate mixing and temperatures of approximately 40-45 ℃. If OCC (old corrugated containers) having a consistency of 4% is used as the fiber source, it is refined to 340C.S.F. freeness before use.

The UV-VIS absorbance of all examples was carried out as follows. After treatment, the fiber slurry was filtered through a 355 micron screen and the filtrate was diluted 10-fold and analyzed for soluble lignin content at 280nm by UV-VIS spectroscopy. The percent reduction in soluble lignin was calculated based on the UV-VIS absorbance values.

The Mutek charge was measured using a Mutek PCD-02 particle charge detector using a 0.001mol/L polydiallyl dimethyl ammonium chloride solution as the titrant. The filtrate was diluted 5-fold prior to Mutek measurement. Turbidity was measured by TD-300 from Hach and recorded in FTU units.

Example 1

Unbleached Kraft pulp (UBK) from the paper mill at a consistency of 4% was used for testing. 250g pulp samples were placed in a 45℃bath for thermal equilibration and then treated with 1 pound/ton of six different polymers each. These polymers are the polymers A-F described above.

After stirring the sample for an additional 10 minutes, it was removed from the bath, cooled to room temperature, and filtered through a 355 micron sieve. The lignin content of the filtrate was assessed by UV-VIS measurement. The percent lignin reduction compared to untreated samples was calculated. Lignin values and percent lignin reduction are summarized in table 1 listed in fig. 1.

The test results show that the specific polymers are more efficient in lignin fixation and removal of lignin from process water (filtrate). The list includes cationic (polymer a) and nonionic (polymer B) polymers. The anionic polymer (polymer E) or the amphoteric polymer (polymer F) is not effective in removing lignin from process water.

Example 2

Dehydrated OCC fibers and synthetic white water were used in the test. The cellulosic fibers and the white water are combined to produce a thick stock having a consistency of approximately 4%. The thick stock treatment test was extended to 3 cycles, where a stock with a consistency of 4% was treated with 1 pound/ton of polymer a and mixed for 30 minutes per cycle, followed by filtration.

The experiment was performed in two ways: after each cycle, white water was separated from the thick stock cellulose fibers by gravity filtration. The filtered white water is then reused in a subsequent step with fresh pulp (this is indicated as process 1 row in table 2 of fig. 2A and 2B) or the same fibers are reused in a subsequent 3 steps (this is indicated as process 2 row in table 2 of fig. 2A and 2B). All collected filtrates were analyzed for lignin content. In either case, a gradual decrease in soluble lignin content is observed, eventually a decrease approaching 70%.

Finally, the test was repeated in a 1-step test in which the thick stock was treated once with 3.0 lbs/ton of polymer a, then the thick stock was filtered, and the filtrate was analyzed for lignin content. Lignin reduction was close to previous experiments (this is shown as treatment 3 in table 2 of fig. 2A and 2B).

These examples show that lignin reduction occurs in a similar manner whether fresh pulp is used for several steps of lignin fixation and removal or the same pulp is used for one or more lignin removal steps. In a paper mill setting, a gradual (gradual) decrease of soluble lignin is contemplated, as "treated" process water may be mixed with "untreated" water for dilution of the pulp.

Example 3

Synthetic white water was used in this test. The dewatered OCC fibers are added to the white water to produce a thick stock having a consistency approaching 4%. Then, 500g of samples were placed in a 45℃bath for 30 minutes, some of which were untreated and others were treated with 1 pound/ton of polymer A, 2 pounds/ton of polymer A, or 3.0 pounds/ton of polymer A. After 30 minutes, all samples were removed from the bath, cooled to room temperature and filtered through a 355 micron sieve. The filtrate was collected and analyzed by UV-VIS at 280nm to determine soluble lignin. In addition, the filtrate was analyzed for COD content. The results are summarized in table 3 of fig. 3 and demonstrate that lignin reduction with polymer concentrate translates into an additional 12%, 14% and 21% reduction in COD content of the white water. This example illustrates that effective lignin reduction with polymer treatment also results in a significant reduction in the COD content of the process water.

Example 4

Thermomechanical pulp (TMP) with a consistency of 4% was used in the following test. The TMP slurry was split into three portions. The first portion was untreated, the second portion was treated with 1 pound/ton of polymer D, and the third portion was treated with 1 pound/ton of polymer a. After treatment, the thick stock sample was placed in a warm bath at 45 ℃ for 30 minutes. The sample was then filtered and the filtrate was collected for drainage testing.

The dynamic drainage analyzer was used to determine drainage activity, and test equipment was available from AB Akribi Kemikonsulter, sundsvall, sweden. The test device applies a vacuum of 300 mbar to the bottom of the separation medium. The device electronically measures the time between vacuum application and the point of vacuum failure, i.e., the time for the air/water interface to pass through the thickened fiber mat. This value was recorded as the drainage time. Typically the drainage time is short. 500ml of slurry was added to DDA and the water filtration test was performed under total instrument vacuum at 300 mbar pressure.

For the drainage test, dewatered TMP fiber (25% consistency) was added to the treated or untreated filtrate to produce a fiber/water slurry with a consistency of 0.7%. The drainage test was performed without drainage aids with polymer D added at 1 and 2 lbs/ton and polymer a added at 1 and 2 lbs/ton. The drainage results (in seconds) and percent improvement (for polymer efficiency) are summarized in table 4 and the graphs of fig. 4A-C. Fig. 4B shows the drainage time in the case of a slurry pretreatment using polymer D and polymer a. Fig. 4C shows the increase in drainage polymer efficiency (%) in the case of slurry pretreatment using polymer D and polymer a. % improvement is calculated based on the difference in drainage time of untreated slurry and treated slurry relative to the drainage time of untreated slurry using the following formula:

Wherein T1 and T2 are the drainage times without and with the polymeric auxiliary, respectively.

In the absence of slurry pretreatment, the drainage times for polymer a and polymer D (43.21 and 44.65 seconds, respectively) were very similar to the drainage time for the samples without any additives (46.93 seconds). The% improvement (i.e., drainage aid efficiency) of the two polymers at 1 lb/ton was very low, 4.86% and 7.93%, respectively.

Pretreatment of the thick stock with 1 lb/ton of polymer a followed by addition of polymer a to the thin stock as a drainage aid resulted in a reduction in drainage time from 43.21 seconds to 27.07 seconds (1 lb/ton) and 20.95 seconds (2 lb/ton). The overall drainage polymer efficiency is improved by 42-55%. However, pretreatment of the thick stock with 1 pound/ton of polymer D did not result in improved drainage time. The drainage time varied from the first 44.65 seconds to 51.07 seconds after 1 pound/ton of polymer D was added and 52.20 seconds after 2 pounds/ton of polymer D was added. The efficiency of the drainage polymer is reduced by 9-11%.

This example demonstrates that only specific polymers can effectively increase chemical efficiency. In this case, polymer a is very effective in reducing drainage time and improving drainage polymer efficiency.

Example 5

Unbleached Kraft (UBK) pulp from a board mill having a consistency of 4% was treated with polymer G at 0.25, 0.50 and 1.0 kg/ton. After the addition of the polymer, a 500g thick stock sample was stirred at 45℃for a further 20 minutes and then filtered. The filtrate was analyzed for lignin content and Mutek charge. Lignin content and Mutek charge values (in ppm and μequ/l, respectively) and lignin and Mutek charge reduction (in%) are summarized in table 5 of fig. 5A. The data indicate that polymer G product effectively reduced lignin and lignin reduction increased with increasing polymer loading. Since lignin is the primary contributor to the Mutek charge, efficient removal of lignin from process water is also accompanied by a significant reduction in Mutek charge.

After laboratory evaluation, lignin management techniques were applied to the paper mill. Polymer G was added to the thick stock of the boxboard paper production process using UBK pulp in an amount of 1.0 kg/ton over the course of several days. The addition of polymer G reduced lignin by up to 30%. Lignin reduction in turn increases machine speed and allows for gradual reduction of the reinforced polymer feed up to 20%. The use of auxiliary anionic polymers is completely eliminated. As reinforcing polymer, a polyvinylamine-based product as well as auxiliary anionic polymers can be used. The machine speed increases while maintaining the paper Strength (STFI) requirement.

The graph of fig. 5B shows the reduction of soluble lignin in the top and bottom layer whitewater. The production consisted of two production lines equipped with two fourdrinier machines, PM #3 and PM #4. During the experiment, polymer G was added to the thick consistency pulp of the bottom layer before the refiner, and for the top layer, the polymer treatment agent was added to the thick pulp after the refiner and just before the refiner chest. The trend towards reduced soluble lignin suggests that the addition after the refiner is more efficient than the addition before the refiner. More specifically, fig. 5b shows lignin reduction in the white water collected from the headbox area of the paper machine (bottom and top layers are created for PM # 4). This illustrates that even partial reduction of lignin in process water by application of lignin fixing polymer product(s) can result in the following significant improvements in papermaking: the machine speed increases and the efficiency of the reinforcing additives increases.

Example 6

In this example, both laboratory tests and paper mill tests were performed. Laboratory tests were performed using unbleached Kraft (UBK) pulp. UBK pulp is produced by intermittent digestion in the pulp section of an integrated paper mill. The pulp is then used by two paper machines PM #1 and PM #3 to produce a wrapper.

In laboratory tests, UKP pulp samples were treated with 0.25, 0.50 and 1.0 kg/ton of polymer G. After the addition of the polymer, a 500g thick stock sample was stirred for a further 20 minutes at 45℃and then filtered. The filtrate was analyzed for lignin content and turbidity. Lignin and turbidity values (in ppm and FTU) and lignin and turbidity reduction (in%) are summarized in table 6A of fig. 6A.

Lignin management techniques are also applied to the paper making process of paper mills. Polymer G was added to the thick stock of both paper machines (PM#1 and PM#3) in an amount of 0.9-1.2 kg/ton. As a result of the polymer treatment, a significant reduction in lignin in the process water of both paper machines has been observed. Graph 6B of fig. 6B shows lignin reduction for one of the paper machines (PM # 1). More specifically, the graph includes a top line representing the level of lignin in the process water in the headbox of the paper machine that produces the bottom layer of the double layer paper making of PM #1 and a bottom line representing the average level of lignin in the process water in the headbox of the paper machine that produces the top layer. The average lignin level was near 400ppm before the test (7 months ago) and was reduced to an average of 150ppm after the addition of polymer G (from 7 months old). Similar lignin reduction was observed on PM # 3. Overall, lignin reduction on PM #1 was nearly 62% and lignin reduction on PM #3 was nearly 57%.

The application of polymer G to the thick stock significantly reduces lignin in the process water and this further improves the papermaking process. These improvements included a significant reduction in turbidity, i.e., from 28% to 62% (see table 6E of fig. 6E). As lignin is reduced, the amount of water used for unbleached pulp washing is reduced by 20%. This change resulted in an increase in conductivity from 2800 to 3500 μS/cm and higher. This allows for the use of a smaller amount of resin/tack contaminant control agent (Detac DC 786C+Performance DC1871, both of the product of Solenis) (67% reduction) (see, e.g., chart 6C of FIG. 6C) and a smaller amount of sizing agent (AKD (alkyl ketene dimer)) (25% reduction) (see, e.g., chart 6D of FIG. 6D). The overall paper machine runnability is improved. The main parameter of the intensity is in the desired specification.

More specifically, graph 6C of fig. 6C illustrates that as the lignin content of the process water effectively decreases, the use of resin/stickies control agent (Detac DC 786c+performance DC 1871) decreases. The top line represents daily average addition and the gray line represents month average. In addition, graph 6D of fig. 6D illustrates that the use of AKD (alkyl ketene dimer) sizing agent decreases with an effective decrease in lignin content of the process water. The top line represents daily average addition and the gray line represents month average. Figure 6E, chart 6E, illustrates the improvement observed in the pulp and paper section with the application of lignin management polymer G.

In addition to improvements in the paper industry, significant advances have been made in the pulping industry. The reduction in the amount of unbleached pulp wash water results in a reduction in black liquor volume. This in turn allows more chip cooking and an increase in cellulose yield, see the results in table 6 e. The average daily pulp production was raised to 8.7%, with a daily maximum value of 12%. Furthermore, the reduction in unbleached pulp wash volume results in an increase in black liquor solids percentage of 1.5%. This variation resulted in increased efficiency of the black liquor evaporator, increased steam production (16.4%) and reduced oil consumption (25%). Lignin management at the paper mill section allows for increased cellulose pulp production, energy savings and reduced fresh water/condensate usage.

While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims.

Furthermore, all of the individual components, process steps, conditions, physical properties, etc. described above are expressly contemplated herein for use together in one or more non-limiting embodiments, even though they may not be described above together. In other words, all combinations of the above-described components, method steps, conditions, physical properties, and the like are hereby expressly contemplated for use in various non-limiting embodiments.

Claims

1. A method of increasing the chemical efficiency of a chemical additive in a papermaking system, the method comprising the steps of:

providing a concentrated pulp comprising soluble lignin, process water, and at least about 2 wt% cellulosic fibers based on the total weight of the concentrated pulp, and

adding at least one organic polymer to the concentrated pulp to reduce the amount of soluble lignin therein; and

wherein the organic polymer is selected from cationic polymers, nonionic polymers, and combinations thereof.

2. The method of claim 1, wherein the concentrated pulp is enzyme-free.

3. The method of claim 1, wherein the concentrated pulp comprises at least about 3% by weight cellulosic fibers based on the total weight of the concentrated pulp and wherein the cellulosic fibers are derived from NSSC pulp, UBK pulp, OCC pulp, deinked pulp, virgin fiber, mechanical pulp, thermomechanical pulp, or a combination thereof.

4. The method of claim 1, wherein the organic polymer is cationic and has the general formula II:

[B-co-C](II)

wherein B is one or more nonionic repeating units formed after polymerization of one or more nonionic monomers, C is one or more different cationic repeating units formed after polymerization of one or more cationic monomers, and-co-means that the polymer is a copolymer of B and C.

5. The method of claim 4, wherein the mole percent of B: C of the nonionic monomer to the cationic monomer of formula II is from about 99:1 to about 50:50.

6. The method of claim 1, wherein the organic polymer has the general formula III:

[-C-]

wherein C is one or more different cationic repeat units formed after polymerization of one or more cationic monomers.

7. The method of claim 1, wherein the organic polymer is selected from the group consisting of cationic polyacrylamides, polyvinyl amines, polyethylenimines, diallyldimethylammonium chloride polymers, trialkylaminoalkyl (meth) acrylamide polymers, epichlorohydrin-dimethylamine copolymers, polyethylene oxide polymers, polyethylene oxide-polypropylene oxide copolymers, polyoxazolines, and combinations thereof.

8. The method of claim 7, wherein the cationic polyacrylamide is derived from at least one monomer selected from the group consisting of: diallyldimethylammonium chloride, N, N, N-trialkylaminoalkyl (meth) acrylate, N, N, N-trialkylaminoalkyl (meth) acrylamide, epichlorohydrin-dimethylamine, and combinations thereof.

9. The method of claim 1, wherein the cationic polymer comprises a polyvinylamine derived from at least one monomer selected from the group consisting of: n-vinylformamide, N-vinylmethylformamide, N-vinylphthalimide, N-vinylsuccinimide, t-butyl N-vinylcarbamate, N-vinylacetamide, and combinations thereof.

10. The method of claim 1, wherein the organic polymer is a polymer dispersion comprising (i) a high molecular weight cationic polyacrylamide having a weight average molecular weight greater than about 1,000,000g/mol and (ii) a low molecular weight cationic dispersant polymer derived from greater than about 50 weight percent cationic monomer and having a weight average molecular weight of from about 100,000 to about 500,000 g/mol.

11. The method of claim 1, wherein the organic polymer is nonionic and has a weight average molecular weight of about 1,000,000 to about 10,000,000 daltons.

12. The method of claim 1, wherein the organic polymer is a polyethylene oxide polymer having a weight average molecular weight greater than about 1,000,000 and less than about 1,000 kilodaltons.

13. The method of claim 1, wherein the organic polymer is a cationic polyacrylamide having a weight average molecular weight greater than about 200,000 and less than about 1,000 kilodaltons.

14. The method of claim 1, wherein the organic polymer is added to the process water in an amount of about 0.05 to about 5 pounds of organic polymer per ton of oven dried pulp.

15. The method of claim 1, wherein the reduction in the amount of soluble lignin in the process water is evidenced by: the absorbance in the UV-VIS spectrum measured after 24 hours at about 280nm is reduced by at least 5% as compared to process water without the at least one organic polymer.

16. The method of claim 1, wherein the process water exhibits a reduction in chemical oxygen demand of at least about 5% as compared to the chemical oxygen demand of process water without the at least one laccase and the at least one organic polymer.

17. The method of claim 1, further comprising the step of adding an inorganic coagulant to the process water, wherein the inorganic coagulant is selected from the group consisting of aluminum sulfate, aluminum chloride, aluminum chlorohydrate, polyaluminum chloride, polyaluminum sulfate, iron (III) chloride, iron (III) sulfate, iron (II) chloride, iron (II) sulfate, iron (II) polysulfate, and combinations thereof.

18. The method of claim 1, further comprising the step of:

providing a thin pulp, and

the at least one organic polymer is added to the thin pulp at the same time as the step of adding the at least one organic polymer to the thick pulp.

19. The method of claim 1, which increases pulp yield by at least 1% as measured in tons of pulp produced per day.

20. The method of claim 1, further comprising the step of providing black liquor having a percent solids at least 0.5% greater than a control method that does not use the at least one organic polymer.