KR20230028218A - Green liquor treatment agent - Google Patents

Abstract

The present invention provides a technique for better processing green liquor.
The present invention is a rust liquid treatment agent comprising a cationic polymer having no ester-bonded cationic group as an active ingredient; a green liquor treatment method in which a cation polymer having no ester-bonded cation groups is added to the crude green liquor; Provided is a calcium carbonate production method including a digestion/causticization step of generating calcium carbonate using a clarified green liquid by adding a cation polymer having no ester-bonded cation group to the crude green liquid.

Description

Green liquor treatment agent

The present invention relates to a green liquor treatment agent, a green liquor treatment method, a method for producing calcium carbonate, and the like.

Pulp is produced by adding treated water containing sodium hydroxide to wood chips and cooking them. Then, in the cooking step, the chips are digested with alkali (white liquor) to obtain pulp, and the cooking agent and heat energy are recovered from the pulp waste liquor (black liquor). Specifically, the drug is recovered by a recovery process including a cooking process, a pulp washing process, a black liquor concentration process, a black liquor burning process, a green liquor manufacturing process, a white liquor manufacturing process, and a lime firing process.

The smelt generated by burning the black liquor contains insoluble impurities (dregs) such as unburned carbon, calcium carbonate, aluminum hydroxide, iron oxide, and silicon dioxide. In addition, wood chips are rich in calcium salts, barium salts, phosphates, cellulose, lignin, etc., which are raw materials for these insoluble impurities, and thus insoluble impurities tend to occur.

This insoluble impurity called drag has an adverse effect on the production of calcium carbonate and the like in the white liquor production step. For this reason, in the green liquor manufacturing process, the drag in the crude green liquor is removed as much as possible, and the green liquor is more well clarified.

For example, in Patent Document 1, 0.5 to 10%, preferably 1 to 5%, of quicklime is added to the unrefined green liquor during stirring to completely causticize the green liquor, and then solid particles are added. A method for refining green liquor characterized by removing it from the green liquor has been proposed.

Patent Document 1: Japanese Patent Application Publication No. 1-502207

The main object of the present invention is to provide a technique for better processing green liquor.

The inventors of the present invention, as a result of repeated intensive studies on techniques for better treating green liquor, found that the green liquor can be better treated by using a cation polymer having no ester-linked cation groups, The invention was completed.

The present invention provides a rust liquid treatment agent containing a cation polymer having no ester-bonded cation groups.

The present invention provides a green liquor treatment method in which a cationic polymer having no ester-bonded cation groups is added to the crude green liquor.

The present invention provides a method for producing calcium carbonate, including a digestion and causticization step of generating calcium carbonate using a clarified green liquor by adding a cation polymer having no ester-bonded cation group to the crude green liquor. .

The present invention is a green liquor clarification step of clarifying the green liquor by adding a cationic polymer having no ester-bonded cation groups to the crude green liquor;

The digestion and causticization process of generating calcium carbonate by digestion and causticization using the green liquor

It is to provide a method for producing calcium carbonate comprising.

The cationic polymer is a polymer having at least a structural unit derived from a cationic monomer having no ester bond,

The cation monomer without an ester bond may be an amine monomer without an ester bond and/or a quaternary ammonium salt monomer without an ester bond.

The cation polymer may be a polydiallyldimethylammonium salt and/or a copolymer thereof; One type or two or more types selected from acrylamide/3-acrylamidepropyl (trimethyl)ammonium salt copolymer, acrylamide/diallyldimethylammonium salt copolymer, and alkylamine/epichlorohydrin polycondensates may be used.

The green liquor treatment may be green liquor clarification.

ADVANTAGE OF THE INVENTION According to this invention, the technique of processing green liquor more favorably can be provided. In addition, the effect described here is not necessarily limited, and any one effect described in this specification may be sufficient.

Fig. 1 is a schematic configuration diagram of a pulp manufacturing system including a green liquor treatment system according to one embodiment of the present invention, but the present invention is not limited thereto.
Fig. 2 is a diagram showing the tendency of the color tone (a* value and b* value) of the green liquor of each chemical treatment in Experimental Example 1. ● is the color change of the green liquor after treatment with each agent of cation + anion or cation, and ○ is the change in color of the green liquor after treatment with each reagent of one anion/positive agent.
Fig. 3 is a diagram showing the tendency of the color tone (a* value and b* value) of the green liquid of each chemical treatment in Experimental Example 2. ● is the color change of the green liquor after treatment with each agent of cation + anion or cation, and ○ is the change in color of the green liquor after treatment with each reagent of one anion/positive agent.
Fig. 4 is a graph showing the addition amount of a crosslinked cation polymer having a quaternary ammonium base group without an ester-bonded cation group and a change in the color tone (green direction) of the clarification green liquor.

Below, the form for implementing this invention is demonstrated. In addition, the embodiment described below shows an example of a typical embodiment of the present invention, and the scope of the present invention is not limitedly interpreted by this. In addition, the upper limit value and the lower limit value in a numerical value can be arbitrarily combined as desired.

As one embodiment related to the green liquor treatment of the present invention, it will be described with reference to Fig. 1, but the present invention is not limited to this.

<1. Pulp manufacturing system and green liquor treatment system in the present embodiment>

<1-1. Overview of Pulp Manufacturing System>

Fig. 1 is a schematic configuration diagram of a pulp manufacturing system 1 provided with a green liquor treatment system according to one embodiment of the present invention, and the present invention is not limited thereto.

The pulp production system 1 may include a cooking system 10, a black liquor treatment system 20, a green liquor clarification system 30, and a digestion/causticization system 40. These systems may be communicated with each other through pipes indicated by solid lines in FIG. 1 to constitute a circulation path as a whole.

Below, each component is demonstrated in detail.

<1-1-1. digester>

The digester 10 may include a digester 11, and a pulp refiner may be provided downstream of the digester 11. Wood chips, which are raw materials for pulp, and white liquor containing sodium hydroxide are put into the digester tube 11, and the wood chips are digested.

The resulting pulp is transported to the pulp refining unit, and paper is manufactured through sequential processes such as bleaching and papermaking. On the other hand, black liquor, which is waste liquid, is transferred to an evaporator 21 described later for recovery of sodium hydroxide.

<1-1-2. Black liquor treatment system>

The black liquor treatment system 20 may include an evaporator 21 and a boiler 22 sequentially from upstream. After being concentrated by the evaporator 21, the black liquor is transferred to the boiler 22 and burned in the boiler 22. As a result, the inorganic sodium salt contained in the black liquor is melted and discharged from the bottom of the boiler 22 as smelt. The discharged smelt is transferred to the melting tank 31.

Further, a heat recovery system for recovering thermal energy may be provided in the boiler 22 . As such a heat recovery system, conventionally known ones can be used (for example, see Japanese Patent Laid-Open No. 6-212586).

<1-1-3. Green liquor clarification system>

The green liquor clarification system 30 may include a dissolution tank 31, a green liquor clarifier 32, and a green liquor tank 33 sequentially from upstream. The smelt is dissolved or dispersed by stirring in water in the dissolution tank 31. This produces a green liquid (also referred to as "crude green liquid") rich in sodium carbonate together with sodium hydroxide. The dissolution tank 31 is provided with a liquid feed pump (not shown), and the crude green liquid is sucked by this liquid feed pump and transferred to the green liquid clarifier 32 . In the crude green liquor, remaining undissolved components are removed in the green liquor clarifyer 32. After that, it is transferred to the green liquor tank 33 and stored, and is transferred to the causticizer 41 as it is.

As the apparatus used for clarification of the green liquor in the present embodiment, a gravity sedimentation type apparatus, a forced filtration type apparatus, and the like are exemplified, but are not particularly limited thereto. Green liquor clarifier, which is representative of the gravity sedimentation method, is preferred.

Examples of the green liquor clarifier include, but are not particularly limited to, multistage clarifiers, unit clarifiers, storage tank combined type clarifiers, and sedimentation and concentration type clarifiers. do.

<1-1-4. Digestion and caustic system>

The digestion/causticization system 40 may include a causticization system 41, a white liquor clarifier 42, and a white liquor tank 43. The fire extinguishing/causticization system 40 may further include a lime mud filter 45 and a kiln 44 located downstream of the white liquor clarifier 42. The causticization system 41, the white liquor clarifier 42, and the white liquor tank 43 communicate with each other and constitute a circulation path as a whole.

The green liquor transferred to the causticization system 41 is mixed with the calcium oxide supplied from the kiln 44 in this causticization system 41. This mixing will be described in more detail.

The causticization system 41 may include a slaker 411 and a plurality of causticization reaction tanks 412 located downstream of the slaker 411 . The green liquor (usually 90 to 100°C, pH 13 to 14) transferred to the slaker 411 is mixed with the calcium oxide supplied to the slaker 411 in the same way. As a result, calcium oxide is digested with water to produce calcium hydroxide. After that, when transferred to the causticization reaction tank 412, sodium carbonate in the green liquor reacts with calcium hydroxide to produce sodium hydroxide and calcium carbonate.

The white liquor thus obtained is transferred to the white liquor clarifier 42 . In the white liquor clarifier 42, after the insoluble calcium carbonate is precipitated and separated, the white liquor is stored in the white liquor tank 43 and circulated to the digester 11 as it is to be reused. On the other hand, the separated calcium carbonate is recovered in the kiln 44, roasted, and returned to calcium oxide, whereby it is reused in the causticization system 41.

<2. Green liquor treatment in this embodiment>

This embodiment can provide a rust liquid treatment agent containing, as an active ingredient, a cationic polymer not provided with an ester-bonded cationic group.

Furthermore, this embodiment can provide a green liquor treatment method in which a cation polymer having no ester-linked cation group or a rust liquor treatment agent containing the polymer is added to the crude green liquor.

In addition, in this embodiment, calcium carbonate is produced using the green liquor clarified by adding a cation polymer having no ester-bonded cation group (hereinafter, also referred to as “cation polymer of this embodiment”) to the crude green liquor. It is possible to provide a method for producing calcium carbonate, including a digestion and causticization step.

The "green liquor treatment" in the present embodiment is a green liquor treatment in the green liquor clarification process and/or digestion/causticization process related to pulp production, and is in a broad sense.

In the green liquor clarification step according to the present embodiment, the color tone (a* value: green (-60) direction) of the green liquor can be further improved by using the cationic polymer of the present embodiment. By this green liquor clarification, it is possible to properly separate the drag from the crude green liquor (water to be treated) containing the drag, and to produce the green liquor with excellent color tone according to the present embodiment.

In addition, by using the green liquor having an excellent color tone (a* value: green (-60) direction) according to the present embodiment, the calcium carbonate according to the present embodiment can be better and stably produced in the digestion and causticization process. there is.

The present inventors have prepared a cationic polymer (eg, cation moiety-OOC-polymer) having a cation group having an ester bond (eg, carboxylate ester (R-OOC-R')) in the crude green solution. The behavior when used for clarification treatment was examined. The present inventors found that a cationic polymer having a cation group having an ester bond under a crude green solution of high pH is hydrolyzed at the ester bond portion, cleavage of the cation group, and generation of an anion group, thereby generating a polymer having an anion group. (e.g., HOOC-polymers) were produced. The present inventors thought that the longer the polymer was used in the crude green liquor, the more hydrolyzed the ester bonded portion of the polymer was, and accordingly the proportion of the polymer having an anionic group increased. And the present inventors thought that a reaction occurs between an anionic group generated by hydrolysis and a cationic group that is not hydrolyzed, and as a result, an aggregate is formed, and defects such as clogging of a drag filter are easily caused by this aggregate. .

In addition, when the crude green liquid is of high pH, the cationic property of the polymer having a cation group having an ester bond gradually decreases due to hydrolysis, and the cation group in the polymer is large because of the large amount of OH ^- which is a hydroxide ion. It was estimated that charge neutralization, the repulsion of the charge within the polymer molecule would disappear, the polymer molecule would shrink, and the effect peculiar to the polymer could no longer be exerted.

Then, as a result of repeated intensive studies, the inventors of the present invention found that a cation polymer having no ester-bonded cation group has an excellent ability to treat rust.

The cationic polymer of the present embodiment tends to hardly cause hydrolysis even under the condition that the green liquid has a high pH, and tends to produce a good condensation action even when the hydroxide ion OH ⁻ is large. Therefore, by using the cationic polymer of the present embodiment, a green liquor having excellent color tone can be produced by stabilizing the green liquor clarification process.

In addition, by generating calcium carbonate using the green liquor produced by the cationic polymer of the present embodiment, the particle size can be further increased by secondary aggregation after calcium carbonate is produced.

When the particle diameter of the generated calcium carbonate is increased, washing and dewatering in the lime mud filter are improved, and the water content of calcium carbonate can also be reduced. By using calcium carbonate with a reduced water content, the heavy oil amount of the subsequent kiln can be reduced, and the sintering rate (CaO/(CaO+CaCO ₃ )×100 (%)) can also be improved.

Therefore, since a larger amount of calcium oxide (quicklime) that can be reused can be secured by the green liquor treatment according to the present embodiment, the amount of quicklime normally purchased can be reduced.

<2-1. Cation Polymer Used in the Present Embodiment>

The cation polymer used in this embodiment is a cation polymer having no ester bonded cation group. The above polymer is meant to include homopolymers and copolymers of acrylamide and the like unless otherwise specified.

It is preferable that the cation polymer of this embodiment is provided with at least the structural unit derived from the cation monomer which does not have an ester bond. Moreover, the said cation polymer may also contain a small amount of structural units derived from the cation monomer which carried out the ester bond, as long as it is within the range which does not impair the effect of this invention.

The cationic polymer may be a homopolymer comprising a structural unit derived from a cation monomer having no ester bond, or a structural unit derived from a cation monomer having no ester bond and a structural unit derived from another monomer. A copolymer comprising units may be used. Also generally as copolymers, random copolymers (eg -ABABBBA-), alternating copolymers (eg -ABABAB-), periodic copolymers (eg -ABBABB-), block copolymers ( For example, there are four types of structures of -AAABBBBB-), and one type of block copolymer is what is called a graft copolymer.

The cation polymer used in this embodiment is not particularly limited as long as it is a cation polymer containing a cation group without an ester bond, and for example, an ester bond to a homopolymer or copolymer that can be used for clarification of a green liquid. a cation polymer introduced with a cation group (preferably, a quaternary ammonium base) not provided with; a homopolymer comprising a cation monomer having no ester bond as a constituent unit; Copolymers comprising a cation monomer having no ester bond and another monomer (which may be an oligomer) as structural units; etc. may also be used.

A "copolymer" in the present embodiment is in a broad sense including a copolymer obtained by polymerizing one or two or more kinds selected from the same or different monomers, oligomers, and polymers as raw materials, unless otherwise specified. Examples of the "copolymer" include "a copolymer obtained by crosslinking a monomer or oligomer (preferably a monomer) and another crosslinkable monomer", "a copolymer obtained by polymerization of a monomer and another monomer", etc. The copolymer is not limited to these. As for other crosslinkable monomers, an acrylamide monomer is preferable.

The colloidal equivalent (meq/g) of the cationic polymer used in the present embodiment is not particularly limited as long as it is cationic, but as a preferable lower limit thereof, it is preferably 0.1 meq/g or more, more preferably 0.2 meq/g or more. , More preferably 1 meq / g or more, more preferably 3 meq / g or more, still more preferably 4 meq / g or more, still more preferably 5 meq / g or more, and the preferred upper limit is not particularly limited. For example, 15 meq/g or less, 10 meq/g or less, 8 meq/g or less, etc. are mentioned, Preferably it is 8 meq/g or less. As the preferred numerical range, it is preferably 0.1 to 15 meq/g, more preferably 0.2 to 8 meq/g. Accordingly, better green liquor treatment (for example, maintenance of green liquor clarification, stabilization of drag withdrawal amount, stabilization of calcium carbonate production, etc., even when there is a change in the components of green liquor) can be performed. . The method for measuring the colloidal equivalent is as described in [Example] to be described later.

The intrinsic viscosity ([η]) of the cationic polymer used in the present embodiment is not particularly limited, but is preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.05 or more, as a preferable lower limit. More preferably 0.1 or more, still more preferably 0.2 or more, and as a preferable upper limit thereof, preferably 50 or less, more preferably 25 or less, still more preferably 10 or less, more preferably 5 or less, more It is more preferably 3 or less, and even more preferably 1 or less. As the preferable numerical range, it is preferably 0.2 to 5. This makes it possible to perform better green liquor treatment (for example, maintenance of green liquor clarification, stabilization of drag withdrawal amount, stabilization of calcium carbonate production, etc., even when there is a change in the components of green liquor). In addition, the measuring method of the said intrinsic viscosity is as described in the [Example] mentioned later.

Examples of the "cationic group not having an ester bond" include, but are not particularly limited to, primary to tertiary amines having no ester bond, quaternary ammonium salts not having an ester bond, etc. , 1 type or 2 or more types selected from the group which consists of these cation groups can be used.

In addition, the cation monomer not having an ester bond is not particularly limited, but as the cation monomer not having an ester bond, an amine monomer not having an ester bond and/or a quaternary class having no ester bond It is preferable that an ammonium salt monomer is contained at least as a structural unit of a cationic polymer, and among these monomers, a quaternary ammonium salt monomer having no ester bond is preferable.

<2-1-1. Amine Monomer>

The amine monomer not having an ester bond is not particularly limited, and examples thereof include ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, and diiso. primary, secondary or tertiary alkylamines such as propylamine, triisopropylamine, monobutylamine and dibutylamine; alkanolamines such as monoisopropanolamine, dimethylaminoethanol, diethylaminoethanol, and methyldiethanolamine; diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, and hexamethylenediamine; alkylenimines such as ethyleneimine and propyleneimine; saturated or unsaturated nitrogen-containing monocyclic systems such as saturated hetero monocycles such as piperazine and morpholine, and unsaturated hetero monocycles such as pyrazine and pyridine; and oligomers thereof.

The number of carbon atoms in the hydrocarbon moiety such as alkyl, alkylene, alkanol, and monocyclic of the amine group-containing monomer is not particularly limited, but is preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms.

One or two or more selected from the group consisting of the above amine monomers can be used.

Among these, as an amine monomer not provided with the said ester bond, alkylamines, alkanolamines, and diamines are preferable, and alkylamines are more preferable.

For example, examples of the alkylamine monomers include ethyleneamines having 2 alkyl atoms. As a monomer of the said ethyleneamines, ethylenediamine etc. are mentioned, for example. Examples of the oligomer include polyethylene polyamines such as diethylene triamine, triethylene tetraamine, tetraethylene pentamine, pentaethylene hexamine, piperazine, and N-aminoethyl piperazine. One or two or more selected from may be used.

<2-1-2. Quaternary Ammonium Salt Monomer>

The quaternary ammonium salt monomer is not particularly limited as long as it can exhibit the effect of the present embodiment, but examples thereof include di(meth)acrylic quaternary ammonium salt monomers, vinylalkyl ammonium salt monomers, and the like. You may use 1 type or 2 or more types in a group.

The "quaternary ammonium salt" is not particularly limited as long as it can exhibit the effect of the present embodiment, but examples include diallylmethylethylammonium ethylsulfate, diallyldimethylammonium chloride, dimethacryldimethylammonium chloride, diallyl N,N-dialkyl-N,N-di(meth)acrylic quaternary ammonium salts such as diethylammonium iodide and diallylmethylpropylammonium iodide; N, N, N-trialkyl quaternary ammonium salts such as 3-acrylamide propyl (trimethyl) ammonium chloride and 3-methacrylamide propyl (trimethyl) ammonium chloride - alkyl (meth) acrylamide; You may use 1 type or 2 or more types. Moreover, although it does not specifically limit as said salt, Halides, such as a bromide and a chloride, etc. are mentioned.

Among the above quaternary ammonium salt monomers, N,N-dialkyl-N,N-di(meth)acrylic quaternary ammonium salts are preferred, and diallyldimethylammonium salts are more preferred.

The "alkyl group" in the "N,N-dialkyl" moiety may be the same or different, but is preferably the same, and the alkyl group preferably has 1 to 10 carbon atoms, methyl, ethyl, A C1-C3 thing, such as n-propyl, is more preferable.

<2-1-3. Acrylamide Monomer>

The acrylamide monomer is not particularly limited, and examples thereof include acrylamide, dimethyl acrylamide, isopropyl acrylamide, diacetone acrylamide, and N,N'-methylenebis(meth)acrylamide. 1 type or 2 or more types can be used.

<2-1-4. Examples of cationic polymers used in the present embodiment>

The cationic polymer used in the present embodiment is not particularly limited, but examples thereof include partially methylolated partially tertiary amine lower alkylated modified products of polyacrylamide, diallyldimethylammonium salt polymers and/or copolymers thereof, N,N Diallyldimethylammonium salt copolymer crosslinked with '-methylenebis(meth)acrylamide, acrylamide/3-acrylamidepropyl(trimethyl)ammonium salt copolymer, acrylamide/diallyldimethylammonium salt copolymer, alkylamine/epichlorohydride It is preferable that it is 1 type, or 2 or more types chosen from the dried polycondensate. Since these do not have a cationic group of an ester bond and are difficult to hydrolyze, the effects of the present invention can be exhibited more satisfactorily.

Among these, polydiallyldimethylammonium chloride and/or copolymers thereof, acrylamide/3-acrylamidepropyl (trimethyl)ammonium chloride copolymer, acrylamide/diallyldimethylammonium chloride copolymer, and alkylamine/epichlorohydrin Polycondensates are preferred.

Further, acrylamide/3-acrylamidepropyl(trimethyl)ammonium chloride copolymer crosslinked with N,N'-methylenebisacrylamide, and/or acrylamide/diallyldimethyl crosslinked with N,N'-methylenebisacrylamide Ammonium chloride copolymers are preferred.

Examples of the copolymer of the diallyldimethylammonium salt (preferably the salt, chloride) include a copolymer of a diallyldimethylammonium salt and a monomer copolymerizable with the diallyldimethylammonium salt.

Examples of the monomer copolymerizable with the diallyldimethylammonium salt include acrylamide, allylamine, diallylamine, methyldiallylamine, acrylic acid, epichlorohydrin, and dimethylamine. Two or more types can be used.

Among these, acrylamide, allylamine, and diallylamine are preferable, and acrylamide is more preferable.

<2-2. Manufacturing method of cationic polymer used in this embodiment>

In the manufacturing method of the cation polymer used for this embodiment, there is no restriction|limiting in particular, A well-known manufacturing method of a cation polymer is employable. Although it does not specifically limit as a manufacturing method of a cationic polymer, For example, a radical polymerization method, an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, bulk polymerization method, etc. are mentioned.

As a manufacturing method of the cationic polymer in this embodiment, for example, a cationic monomer (preferably a quaternary ammonium salt monomer) not provided with an ester bond is added to water and mixed. Other monomers (preferably, crosslinkable monomers) are further added to water as needed. A water-soluble polymerization initiator is added to an aqueous solution containing at least a cation monomer having no ester bond, and the atmosphere is substituted with an inert gas and polymerized by heating to obtain a cationic polymer having no ester bond cation group. there is. Moreover, when synthesizing the cationic polymer of this embodiment, an oligomer can also be used as a raw material of a monomer.

It is preferable to use 0.05-500 ppm (weight ratio) of said other monomer (preferably crosslinkable monomer) with respect to "cationic monomer which does not have an ester bond." When the amount of the other monomer (preferably, the crosslinkable monomer) is present, the degree of crosslinking becomes more favorable, and the performance as a rust liquid treatment agent of the cationic polymer of the present embodiment obtained can be exhibited more favorably.

The polymerization initiator used is not particularly limited, and examples thereof include 2,2'-azobis(2-amidinopropane) dihydrochloride, 4,4'-azobis(4-cyanovaleric acid), and 2,2'. -Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobisisobutylamide dihydrate, azobisisobutyronitrile, 2,2'-azobis(2 azo initiators such as ,4-dimethylvaleronitrile); and redox initiators obtained by combining peroxides such as persulfates and alkyl peroxide compounds with sulfites, ferrous salts, amine compounds, and the like.

Moreover, in the presence of a photosensitizer such as benzophenone or benzoin ethyl ether, it can also be polymerized by light irradiation. Among these, water-soluble azo-type initiators can be suitably used.

According to the manufacturing method of this embodiment, the cation polymer used in this embodiment which does not have an ester bonded cation group can be manufactured. Moreover, it is preferable that the said cationic polymer is a polymer provided with at least the structural unit derived from the cationic monomer which does not have an ester bond, and it is more preferable that it is a crosslinked polymer.

<2-2-1. An example of a method for producing cationic polymers used in the present embodiment>

Production of a diallyldimethylammonium salt polymer, an acrylamide/diallyldimethylammonium salt copolymer, or an acrylamide/3-acrylamidepropyl (trimethyl)ammonium salt copolymer, etc. as an example of a method for producing a cationic polymer used in the present embodiment. The method is described below.

There is no particular limitation on the method for producing the diallyldimethylammonium salt polymer (homopolymer) or copolymer (copolymer) or acrylamide/3-acrylamidepropyl (trimethyl)ammonium salt copolymer in the present embodiment. In addition, the salt is preferably a chloride.

For example, a diallyldimethylammonium salt monomer or a 3-acrylamidepropyl(trimethyl)ammonium salt monomer and other monomers (preferably a polyfunctional crosslinkable monomer) are dissolved in water as necessary, and the dissolved solution is water-soluble. Add polymerization initiator. After the addition, by replacing the atmosphere with an inert gas and heating, a crosslinked diallyldimethylammonium salt polymer or copolymer or a crosslinked acrylamide/3-acrylamidepropyl(trimethyl)ammonium salt copolymer can be obtained.

As other monomers used in the present embodiment, there is no particular limitation, and examples thereof include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and propylene glycol di( meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, N,N'-methylenebis(meth)acrylamide, glycerin tri(meth)acrylate, diallyl phthalate, Diallyl Maleate, Diallylamine, Ethylene Glycol Diallyl Ether, Triallylamine, Triallyl Trimellitate, Triallyl Isocyanurate, Triallyl Phosphate, Divinylbenzene, Ethylene Glycol Diglycidyl Ether, Polyethylene Glycol diglycidyl ether, di- or polyglycidyl ether of aliphatic polyhydric alcohol, N-methylol acrylamide, glycidyl methacrylate, etc., and one type or two or more types from the group consisting of these can be used Said other monomer can be used as a polyfunctional crosslinkable monomer. Monomers other than the polyfunctional crosslinkable monomer may be further used as long as they do not impair the effects of the present invention. and those not substantially contained (for example, 1.0% or less, 0.5% or less, 0.1% or less, etc. in 100% by mass of all monomer units constituting the polymer).

Among these, N,N'-methylenebis(meth)acrylamide can be suitably used.

The other monomer is preferably used in an amount of 0.05 to 500 ppm (weight ratio) relative to the diallyldimethylammonium salt monomer or the 3-acrylamidepropyl(trimethyl)ammonium salt monomer. When the amount of the crosslinkable monomer is present, the degree of crosslinking does not decrease and does not become excessively high, and the performance as a rust liquid treatment agent can be sufficiently exhibited.

There is no particular limitation on the constituent units of the diallyldimethylammonium salt polymer used in the present embodiment. For example, a cyclic structure such as a 6-membered piperidinium ring or a 5-membered pyrrolidinium ring may be included, or a polymer in which these two types of structures coexist may be used. Among these, it is preferable to use a linear or branched (preferably straight) chain of diallyldimethylammonium salt as a constituent unit.

Further, the diallyldimethylammonium salt copolymer may be a cationic polymer having only cationic structural units, or, within a range not impairing the effect of the present invention, a copolymer comprising cationic structural units and anionic structural units is obtained. An amphoteric polymer may be sufficient.

Examples of the copolymer of diallyldimethylammonium chloride include copolymers of diallyldimethylammonium chloride and a monomer copolymerizable with the diallyldimethylammonium chloride. Examples of the monomer copolymerizable with diallyldimethylammonium chloride include acrylamide, allylamine, diallylamine, methyldiallylamine, acrylic acid, epichlorohydrin, and dimethylamine. One or two or more selected ones can be used. Among the above copolymers, crosslinked polymers are more preferred.

Among them, one or two or more selected from acrylamide, allylamine, and diallylamine are preferred.

<3. Green liquor treatment agent of the present embodiment>

The rust liquid treatment agent or composition of this embodiment contains the cationic polymer of this embodiment described above as an active ingredient. Configurations overlapping with the above <1.> and <2.> are appropriately omitted.

The rust liquid treatment agent of the present embodiment can be used as an aqueous solution in which the cationic polymer having no ester-bonded cation group is dissolved or suspended in water, but is not particularly limited thereto, and can be used, for example, in the form of slurry or powder. may be The green liquor treatment agent of this embodiment can also be used as a chemical for producing calcium carbonate.

In addition, the green liquor treatment can be satisfactorily performed by using the cation polymer having no ester bonded cation group of the present embodiment as an active ingredient. In addition, by using the cationic polymer having no ester-bonded cation group of the present embodiment for the green liquor treatment, the green liquor can be better clarified or calcium carbonate can be produced more favorably using the clarified green liquor.

Therefore, the cationic polymer having no ester-linked cation group of the present embodiment can be incorporated into a rust liquid treatment agent or a drug for producing calcium carbonate, and can also be used to prepare a rust liquid treatment agent or a drug for producing calcium carbonate. there is.

In addition, this embodiment can also provide the cation polymer which does not have the said ester bonded cation group, or its use, in order to use for green liquor treatment or to improve rust liquor treatment. This embodiment can also provide the cation polymer which does not have the said ester bonded cation group, or its use, for use in calcium carbonate production or to make calcium carbonate production more favorable. This embodiment can provide the use of the cationic polymer having no cation group bonded to the ester bond for green liquor treatment or calcium carbonate production.

In addition, this embodiment can also provide the green liquor processing method, the manufacturing method of clarification green liquor, and the manufacturing method of calcium carbonate. In this embodiment, it is also possible to provide a green liquor treatment method, a clarification green liquor manufacturing method, and a calcium carbonate manufacturing method in which a cationic polymer having no ester-bonded cation group or a drug containing the polymer is added or used. do.

<3-1. Random Ingredients>

The rust liquid treatment agent or composition of the present embodiment may contain or mix any drug as an optional component within a range that does not impair the effects of the present invention.

As optional agents, for example, anticorrosive agents (corrosion inhibitors), scale inhibitors, slime control agents, solvents or dispersion media such as water, dispersing agents, enzymes, disinfectants and antifoaming agents, anionic polymers, cationic polymers other than the present embodiment, Examples include amphoteric polymers and nonionic polymers, but are not limited thereto, and various agents generally usable for green liquor treatment or calcium carbonate production may be used. One type or two or more types selected from the group consisting of these can be used.

At this time, the rust liquid treatment agent or composition of the present embodiment may be a one-component drug containing the cationic polymer of the present embodiment, or a multi-component drug such as a two-component or three-component drug composed of a combination with selected components (for example, , drug kit) can also be used. When using the cationic polymer of the present embodiment, other drugs and selected components may be added simultaneously or separately to the water to be treated, and the order of addition can be appropriately set. Further, it is preferable to add the selected arbitrary drug to the same place as the place where the cationic polymer of the present embodiment is added, or upstream or downstream of the place where it is added, and close to the place where it is added. The rust liquid treatment agent or composition may be used as a drug for producing calcium carbonate.

It is preferable that the rust liquor treatment agent or composition of this embodiment further contain an anionic polymer from a viewpoint of rust liquor treatment and cost. At this time, the rust liquid treatment agent or composition of the present embodiment may be used as a one-component drug containing the cationic polymer of the present embodiment, or as a two-component drug (for example, a drug kit) composed of a combination thereof. possible. In addition, when using the said anionic polymer, you may add simultaneously or separately with the cation polymer of this embodiment with respect to the water to be treated. The anionic polymer can be added at a location close to the addition site of the cation polymer of the present embodiment, and can be added after or before addition of the cation polymer of the present embodiment. Moreover, it is more preferable to add the said anionic polymer after addition of the cationic polymer of this embodiment. The rust liquid treatment agent or composition may be used as a drug for producing calcium carbonate.

The colloid equivalent (meq/g) of the anionic polymer is not particularly limited as long as it is anionic, but as a preferable upper limit thereof, it is preferably -1.0 meq/g or less, more preferably -2.0 meq/g or less, still more preferably It is preferably -2.5 meq/g or less, and as a preferable lower limit thereof, it is preferably -8.0 meq/g or more, more preferably -5.0 meq/g or more, still more preferably -4.5 meq/g or more. As the preferred numerical range, it is preferably -8.0 to -0.5 meq/g, more preferably -4.5 to -2.5 meq/g. Better green liquor treatment (for example, maintenance of green liquor clarification, stabilization of drag withdrawal amount, stabilization of calcium carbonate production, etc.) can be carried out. The method for measuring the colloidal equivalent is as described in [Example] to be described later.

The intrinsic viscosity ([η]) of the anionic polymer is not particularly limited, but as a preferable lower limit thereof, it is preferably 1 or more, more preferably 5 or more, still more preferably 10 or more, still more preferably 15 or more, and as a preferable upper limit thereof, it is preferably 100 or less, more preferably 80 or less, even more preferably 50 or less, and still more preferably 40 or less. As the preferred numerical range, it is preferably 5 to 50, more preferably 15 to 40. By using in combination with the cationic polymer of the present embodiment, better green liquor treatment (for example, even when there is a change in the components of the green liquor, maintenance of green liquor clarification, stabilization of drag withdrawal amount, stabilization of calcium carbonate production, etc.) can be carried out. In addition, the measuring method of the said intrinsic viscosity is as described in the [Example] mentioned later.

Although it does not specifically limit as said anionic polymer, It is preferable to employ|adopt what can be used as a polymer flocculant, and what can be used for the clarification process of green liquor is more preferable.

Examples of the anionic polymer include poly(meth)acrylate-based polymers or copolymers, anionic poly(meth)acrylamide-based polymers, and (meth)acrylate-(meth)acrylamide copolymers. One type or two or more types selected from the group consisting of these can be used. Examples of the salt include alkali metal salts (eg, sodium, potassium, etc.), but are not particularly limited thereto.

Among them, poly(meth)acrylate-based polymers or copolymers are preferred, and (meth)acrylate/(meth)acrylamide copolymers are more preferred.

<4. Green liquor treatment method by cationic polymer of the present embodiment>

<4-1. Green liquor treatment method of the present embodiment>

The cationic polymer of the present embodiment or the green liquor treatment agent containing the polymer (hereinafter also referred to as "agent of the present embodiment") can treat green liquor by adding it to the water to be treated in the green liquor treatment system. For example, green liquor can be clarified more favorably, and calcium carbonate having a larger particle size or a lower water content can be efficiently produced from the green liquor. In addition, about the structure overlapping with said <1.> - <3.>, it abbreviate|omits suitably.

<4-1-1. Water to be treated>

Crude green liquor is mentioned as the water to be treated for clarification of the green liquor in the present embodiment.

The pH (at the time of measurement, 20°C) in the water to be treated in the present embodiment is high alkalinity, for example, preferably 9 or more, more preferably 10 or more, still more preferably 11 or more, even more preferably It is preferably 12 or more, particularly preferably 13 or more.

The suspended solid matter (SS) in the water to be treated in the present embodiment is not particularly limited, but as a preferable lower limit thereof, it is preferably 100 mg/L or more, more preferably 200 mg/L or more, still more preferably 300 mg/L. L or more, even more preferably 400 mg/L or more, and as a preferable upper limit thereof, preferably 1500 mg/L or less, more preferably 1000 mg/L or less, still more preferably 900 mg/L or less, still more preferably It is 800 mg/L or less.

Total iron in the water to be treated in the present embodiment is not particularly limited, but as a preferable lower limit thereof, it is preferably 1 mg/L or more, more preferably 2 mg/L or more, still more preferably 5 mg/L or more, , as its preferable upper limit, preferably 100 mg/L or less, more preferably 80 mg/L or less, still more preferably 50 mg/L or less.

The amount of ionic iron in the water to be treated in the present embodiment is not particularly limited, but as a preferable lower limit thereof, it is preferably 0.01 mg/L or more, more preferably 0.05 mg/L or more, still more preferably 0.1 mg. /L or more, and as a preferable upper limit thereof, it is preferably 10 mg/L or less, more preferably 5 mg/L or less, still more preferably 3 mg/L or less.

The total organic carbon (TOC) in the water to be treated in the present embodiment is not particularly limited, but as a preferable lower limit thereof, it is preferably 5 mg/L or more, more preferably 10 mg/L or more, still more preferably 50 mg /L or more, and as a preferable upper limit thereof, it is preferably 2000 mg/L or less, more preferably 1500 mg/L or less, still more preferably 1000 mg/L or less.

The water quality of the water to be treated in the present embodiment is not particularly limited, but it is preferable to consider one or more water quality conditions selected from pH, SS, total iron, ionic iron, and TOC. By setting the above water quality conditions within the preferred range, better green liquor treatment can be performed, and in the case of water to be treated within the above numerical range, appropriate use of the cation polymer of the present embodiment improves the green liquor clarification and work efficiency. desirable from the point of view

<4-1-2. Place of Addition of Drugs of the Present Embodiment>

The chemical of the present embodiment can be added to an appropriate place in the green liquor treatment system. The place is not particularly limited, and each processing device, processing system, piping, flow path system, and the like are exemplified. For example, it is preferable that the chemical|medical agent of this embodiment is added to the place where green liquor treatment is required or upstream therefrom. At this time, it is preferable that a stirrer or a mixer is provided at the place or upstream so that the water to be treated and the drug of the present embodiment can be easily mixed.

Further, in the present embodiment, it is preferable to provide a chemical agent adding device for introducing the chemical of the present embodiment into the green liquor treatment system and a flow path or pipe for introducing the chemical of the present embodiment into the green liquor treatment system. For example, the agent of the present embodiment can be added to the dissolution tank 31 or the green liquor clarifier 32, or added to water for dissolving the smelt.

It is preferable to add the chemical agent of the present embodiment between the dissolution tank 31 and the green liquid clarifier 32, and it is preferable to add it to the flow path, piping, equipment, etc. provided between them from the viewpoint of work efficiency. more preferable

In the case of using and adding the cationic polymer and anionic polymer of the present embodiment in combination, it is preferable to add both of them simultaneously or separately between the dissolution tank 31 and the green liquor clarifyer 32, From the standpoint of green liquor treatment and cost, it is preferable to add to the water to be treated in the order of the cationic polymer of the present embodiment and then the anionic polymer.

<4-1-3. Amount of Addition of Chemicals in the Present Embodiment to Water to be Treated>

The addition amount and addition period of the cationic polymer of the present embodiment may be appropriately set according to the state of the water to be treated, the flow amount of the fluid, and the like. The addition amount is not particularly limited, but is preferably 0.1 mg/L or more, and more preferably 0.5 mg/L as a preferable lower limit with respect to the fluid (for example, crude green liquor) from the viewpoint of green liquor treatment and cost. L or more, more preferably 1 mg/L or more, even more preferably 2 mg/L or more, still more preferably 3 mg/L or more, and as a preferable upper limit, 1000 mg/L or less, preferably 500 mg/L or less , More preferably 100 mg/L or less, still more preferably 50 mg/L or less, even more preferably 30 mg/L or less, still more preferably 20 mg/L or less, and as the above preferred numerical range, preferably 0.1 to 1000 mg/L, more preferably 1 to 50 mg/L.

Further, the volume of the flowing fluid can be calculated based on the measured value, for example, by arranging a flow meter at an appropriate location in the flow path of the fluid.

The addition period of the cationic polymer of the present embodiment is not particularly limited, but it can be set to obtain a desired color tone by checking the color tone of the green liquid in the green liquid clarifier or the green liquid tank. For example, it is also possible to set so that the effect of this embodiment can be exhibited after addition for 1 to 24 hours (preferably, 6 to 20 hours). You may add the cationic polymer of this embodiment continuously or discontinuously (turn ON/OFF addition at every fixed interval, etc.).

In the case of using the cationic polymer and anionic polymer of the present embodiment in combination, the addition amount of the anionic polymer may be appropriately set depending on the state of the water to be treated, the flow amount of the fluid, and the like.

From the viewpoint of rust treatment and cost, it is preferable to use 0.01 to 1 part by mass of an anionic polymer, more preferably 0.05 to 0.5 part by mass of an anionic polymer with respect to 1 part by mass of the cationic polymer of the present embodiment.

The addition amount of the anionic polymer when used in combination is not particularly limited, but is preferably 0.01 mg/L or more as a preferable lower limit with respect to the fluid (for example, crude green liquor) from the viewpoint of green liquor treatment and cost. , More preferably 0.05 mg/L or more, still more preferably 0.11 mg/L or more, and as a preferable upper limit thereof, 100 mg/L or less, preferably 50 mg/L or less, more preferably 10 mg/L or less, and even more It is preferably 5 mg/L or less, and as the above preferred numerical range, it is preferably 0.01 to 100 mg/L, more preferably 0.01 to 10 mg/L.

In the green liquor treatment method of the present embodiment, the chemical of the present embodiment is added to the water to be treated (for example, crude green liquor), and the green liquor clarification step and digestion/causticization step are performed, thereby obtaining an excellent clarification green liquor and an excellent green liquor. Calcium carbonate can be obtained.

<4-1-4. Clarified green liquor and calcium carbonate in the present embodiment>

The green liquor clarified by the green liquor clarification treatment of the present embodiment preferably has a dull red color and a dark green color (a* value -60 direction). In addition, the range of numerical values of a* value and b* value is ±60.

The a* value of the clarification green liquor in the L*a*b* color system is not particularly limited, but is preferably 1.5 or less, more preferably 1.0 or less, still more preferably 0 or less, and still more preferably -0.5 or less, particularly preferably -1.0 or less, particularly preferably -1.5 or less. In addition, “below” of the a* value means that it approaches -60.

The lower limit of the particle size of the calcium carbonate produced by the calcium carbonate generation treatment of the present embodiment is preferably 5 μm or more, more preferably 10 μm or more, and the upper limit is not particularly limited, but is, for example, 150 A micrometer or less and 100 micrometers or less are mentioned. The larger the particle size is, the more preferable it is from the viewpoint of work efficiency and reuse.

(Measurement method of particle size)

Calcium carbonate is dispersed in water, and carbonic acid is obtained by a laser diffraction/scattering particle size distribution measurement method (e.g., laser diffraction/scattering particle size distribution measuring instrument LA-300 manufactured by HORIBA, Ltd.). Measure the particle diameter (median diameter) of calcium.

In addition, the moisture content of the produced calcium carbonate is preferably 25% or less, more preferably 20% or less. The lower the moisture content is, the more preferable it is from the viewpoint of work efficiency and reuse.

(How to measure moisture content)

A method using a dryer, a method of heating and drying by infrared rays, a method using near infrared rays, and the like are exemplified.

The method by the dryer is performed in accordance with JIS P 8202, which tests the absolute drying rate of pulp, and samples are taken and left to dry overnight in a constant temperature heating dryer at 105 ° C., and then dried in a desiccator. It is measured by returning to room temperature in the room and determining the moisture content from the weight difference of the sample before and after drying.

The method of heating and drying by infrared rays can quickly measure the moisture content. A sample is placed in "Kurigansui" (trade name) manufactured by Kurita Water Industries Ltd., infrared rays are irradiated, and the moisture content is measured from the mass change due to evaporation of moisture.

The method using near-infrared rays is carried out using a near-infrared moisture meter "KJT-130" (trade name) manufactured by Kett Electric Laboratory Co. Ltd., or the like. Since near-infrared rays have a longer wavelength than visible rays, are outside of red, and are invisible to the naked eye, and are well absorbed by moisture, the moisture content is measured by irradiating light including near-infrared rays and measuring the reflectance.

In the examples shown in Table 7, it was determined by a method using a dryer.

<4-2. Manufacturing method of clarification green liquor and calcium carbonate of the present embodiment>

By using the agent of the present embodiment, a better clarification green liquor and a better calcium carbonate can be produced. In addition, about the structure overlapping with said <1.> - <3.> and <4-1.>, it abbreviate|omits suitably.

The green liquor treatment method of the present embodiment includes (A) a green liquor clarification step in which the green liquor is clarified by adding the chemical of the present embodiment to the crude green liquor, and (B) a digestion reaction and a causticization reaction using the green liquor It is preferable to include a digestion and causticization step of generating calcium carbonate by the.

Further, by the green liquor treatment of the present embodiment, it is possible to add the drug of the present embodiment to the crude green liquor to produce a clarified green liquor, and to produce calcium carbonate using the green liquor.

In the green liquor clarification method of the present embodiment, it is preferable to add the drug of the present embodiment to the crude green liquor to clarify the green liquor.

In the digestion and causticization method of the present embodiment, it is preferable to produce calcium carbonate using the green liquor obtained by the green liquor clarification method.

The method for producing calcium carbonate of the present embodiment preferably includes a digestion/causticization step of producing calcium carbonate by using a clarified green liquor by adding a cation polymer having no ester-bonded cation groups to the crude green liquor. do.

The method for producing calcium carbonate of the present embodiment includes (A) a green liquor clarification step in which a cation polymer having substantially no ester-bonded cation groups is added to the crude green liquor to clarify the green liquor; (B) the green liquor is used Therefore, it is preferable to include a digestion and causticization step of generating calcium carbonate by a digestion reaction and a causticization reaction.

Accordingly, excellent calcium carbonate can be produced.

It is also possible to realize the processing method of the present invention with a control unit including a CPU or the like in a device (for example, a computer, PLC, server, cloud service, etc.) for managing the green liquor processing and the like. It is also possible to store the processing method of the present invention as a program in a hardware resource including a recording medium (non-volatile memory (USB memory, etc.), HDD, CD, DVD, Blu-ray, etc.) and realize it with the control unit. . It is also possible to provide a device having the control unit or the system, such as a green liquid treatment system that controls, by the control unit, to add a drug to the water to be treated (for example, for adjusting the color tone of the green liquid). . Further, the management device may include an input unit such as a keyboard, a communication unit such as a network, and a display unit such as a display.

The present invention can also employ the following structures.

〔One〕

A rust liquid treatment agent or composition containing a cation polymer having no ester-bonded cation groups. The rust liquid treatment agent or composition may be a rust liquid treatment agent or composition for use in combination with an anionic polymer.

〔2〕

A cationic polymer having no ester-linked cation group or its use for producing a green liquor treatment agent or a drug for the production of calcium carbonate. The rust liquid treatment agent or agent for producing calcium carbonate may be a rust liquid treatment agent for use in combination with an anionic polymer or a drug for producing calcium carbonate.

[3]

A cation polymer not having an ester-bonded cation group for use in rust treatment or rust treatment, or its use. A cation polymer not having an ester-linked cation group for use in the production of calcium carbonate or calcium carbonate, or its use. A cationic polymer not provided with an ester bonded cation group may be used in combination with an anionic polymer.

〔4〕

A green liquor treatment method comprising adding a cationic polymer having no ester-linked cation groups or a treatment agent containing the above to crude green liquor. The green liquor treatment is preferably green liquor clarification and/or digestion/causticization or generation of calcium carbonate. A preferable place for addition is between the dissolution tank and the green liquor clarifier.

[5]

A method for producing calcium carbonate, comprising a digestion/causticization step of producing calcium carbonate using a clarified green liquor by adding a cation polymer having no ester-bonded cation group or a treatment agent containing the same to the crude green liquor.

[6]

A green liquor clarification step of clarifying the green liquor by adding a cation polymer having no ester-bonded cation group or a treatment agent containing the above to the crude green liquor;

The digestion and causticization process of generating calcium carbonate by digestion and causticization using the green liquor

Calcium carbonate manufacturing method comprising.

[7]

It is preferable that the cation polymer of any one of said [1]-[6] is a polymer provided with at least the structural unit derived from the cation monomer which does not have an ester bond.

More preferably, the cationic monomer without an ester bond is an amine monomer without an ester bond and/or a quaternary ammonium salt monomer without an ester bond.

More preferably, when the said polymer is a copolymer, it is a crosslinked copolymer which has the structural unit derived from the cation monomer which does not have the said ester bond, and the structural unit derived from another crosslinkable monomer. It is preferable that the structural unit derived from the said other crosslinkable monomer is an acrylamide monomer (preferably N,N'-methylenebis (meth)acrylamide). The copolymer is preferably a cationic copolymer crosslinked with an acrylamide monomer, more preferably a cationic copolymer crosslinked with N,N'-methylenebis(meth)acrylamide, still more preferably N, It is a cationic copolymer crosslinked with N'-methylenebisacrylamide.

〔8〕

The colloid equivalent (meq/g) of any one of the above [1] to [7] is 0.1 to 15 meq/g, and/or the intrinsic viscosity ([η]) of the cation polymer is 0.2 to 5 It is desirable to be

[9]

It is preferable that the cation monomer having no ester bond in any one of the above [1] to [8] is a quaternary ammonium salt monomer, more preferably N,N-dialkyl-N,N-di( It is a meth)acrylic quaternary ammonium salt.

[10]

A polydiallyldimethylammonium salt in which the cationic polymer of any one of the above [1] to [9] is crosslinked with a polydiallyldimethylammonium salt and/or a copolymer thereof or N,N'-methylenebis(meth)acrylamide air It is preferable that it is 1 type(s) or 2 or more types selected from a copolymer, an acrylamide/3-acrylamide propyl (trimethyl)ammonium salt copolymer, an acrylamide/diallyldimethylammonium salt copolymer, and an alkylamine/epichlorohydrin polycondensate. As the salt, chloride or bromide is preferred. More preferably, polydiallyldimethylammonium salt copolymer crosslinked with N,N'-methylenebis(meth)acrylamide, acrylamide/3-acrylamidepropyl(trimethyl)ammonium salt copolymer, acrylamide/diallyldimethylammonium salt It is 1 type, or 2 or more types chosen from a copolymer.

[11]

It is preferable that the addition amount of the cation polymer of any one of said [1]-[10] is 0.1-1000 mg/L with respect to water to be treated.

[12]

It is preferable to further combine an anionic polymer with the cationic polymer of any one of said [1]-[11].

As the anionic polymer, a poly(meth)acrylate-based polymer or copolymer is preferable.

Although the order of addition of the cation polymer and the anionic polymer is not particularly limited, it is preferable to add the cation polymer and then the anionic polymer to the water to be treated in this order.

Preferably, 0.01 to 1 part by mass of the anionic polymer is used with respect to 1 part by mass of the cationic polymer.

[Example]

Embodiments of the present invention will be described with reference to the following experimental examples and test examples. In addition, the scope of the present invention is not limited to experimental examples, test examples, and the like.

[Experimental Example 1: Drugs 1 to 13 / Experimental Example 2: Drugs 14 to 19]

In Test Examples (No.) 1 to 13 related to Experimental Example 1, crude green liquid 1 (Table 1) and each of the chemicals 1 to 13 (Table 3) were used.

In Test Examples (No.) 14 to 19 related to Experimental Example 2, crude green liquid 2 (Table 1) and each of the chemicals 14 to 19 (Table 5) were used.

<Agents in Tables 2 to 5>

Anion 1: Sodium acrylate/acrylamide copolymer

Anion 2: Sodium acrylate/acrylamide copolymer

Anion 3: Sodium acrylate/acrylamide copolymer

Anion 4: Sodium acrylate/acrylamide copolymer

Positive 1: copolymer of sodium acrylate, acrylamide, 2 (methacryloyloxy) ethyltrimethylammonium chloride and 2 (acryloyloxy) ethyltrimethylammonium chloride

Cation 1: Acrylamide 2 (acryloyloxy) ethyltrimethylammonium chloride copolymer

Cation 2: Acrylamide 2 (acryloyloxy) ethyltrimethylammonium chloride copolymer

Cation 3: Styrene 2-methacryloyloxyethyltrimethylammonium chloride copolymer

Cation 4: partially methylolated partial tertiary amine lower alkylation modified product of polyacrylamide

Cation 5: Quaternary salt of dimethylamine/epichlorohydrin polycondensate

Cation 6: Quaternary salt of polycondensate of polyethylene polyamine, dimethylamine and epichlorohydrin

Cation 7: Special acrylamide/diallyldimethylammonium chloride copolymer

Cation 8: Special acrylamide 3-acrylamide propyl (trimethyl) ammonium chloride copolymer

Cation 9: Special polydiallyldimethylammonium chloride

Cation 10: Acrylamide-diallyldimethylammonium chloride copolymer

Cation 11: Acrylamide-diallyldimethylammonium chloride copolymer

Cation 12: Acrylamide/diallyldimethylammonium chloride copolymer

In addition, the crude green liquor used in this experimental example is a crude green liquor containing smelt produced when pulp was manufactured in a paper mill.

Moreover, in the case of a cationic polymer copolymer, the crosslinkable monomer is within the range of 0.1 to 100 ppm in weight ratio with respect to the cationic group-containing monomer.

The experimental conditions of Experimental Example 1 and Experimental Example 2 are as follows.

Table 1 shows the water quality of crude green liquor 1 and crude green liquor 2 used in the laboratory test. Water quality with high TOC and crude green liquor with high Fe content was used.

<Experiment conditions>

The green liquor clarified treatment was evaluated and implemented in a laboratory test by means of a jar test.

After adding and mixing agent I to the water to be treated, agent II was added and mixed. Compared with the green liquor treatment with an anionic polymer alone, the improvement of the water quality of treated water by using agent I was confirmed.

500 mL of the green liquid was taken and measured with a ruler tester.

Stirring conditions 150 rpm×30 seconds → 60 rpm×90 seconds

Stop stirring and take a picture of the supernatant after 3 minutes, and for the change in color tone, a* of L*a*b* color space (JIS Z 8781-4) with a color sensor (ColorTouch 2 Model ISO, manufactured by Technidyne). The value, b* value was obtained. When the green liquor treatment is improved, the reddish green liquor becomes green, so a lower a* value indicates better treatment (Reference 1; Ishikawa Norio, Journal of the Japanese Society of Burns, 2005, Vol. 44, 6) No., p.489-498).

<Method of measuring intrinsic viscosity>

The method for measuring the intrinsic viscosity of a polymer in the present specification can be carried out based on JIS K 7367-1: 2002 "Method for Determining the Viscosity of a Diluted Polymer Solution Using a Plastic-Capillary Viscometer - Part 1: General Rules" there is.

The intrinsic viscosity of the cationic polymer and amphoteric polymer in this specification is dissolved in a solvent of 1.0 N sodium nitrate aqueous solution so that the concentration is 0.1%, 0.08%, 0.06%, 0.04%, and 0.02%, and Canon-Fenske It is measured at 30 ° C. with a (Cannon-Fenske) type viscometer (e.g., manufactured by Kusano Scientific Co., Ltd.), the concentration is plotted on the horizontal axis and the reduced viscosity is on the vertical axis, and each value is plotted, and the straight line is extrapolated to zero concentration.

The intrinsic viscosity of the anionic polymer in this specification is dissolved in a solvent of 1.0 N NaCl aqueous solution so that the concentration is 0.08%, 0.06%, 0.05%, 0.04%, and 0.02%, and a Canon-Fenske type viscometer (eg : Measured at 30 ° C. by Kusano Science Co., Ltd.), plotted each value with the concentration as the horizontal axis and the reduced viscosity as the vertical axis, and obtained by extrapolating the straight line to zero concentration.

<Measurement method of ionicity (colloidal equivalent)>

The ionicity of the polymer in this specification is calculated as a colloidal equivalent. The measurement of "colloid equivalent (meq/g)" in this specification is based on "Colloid Titration Method" (Reference 2; Ryoichi Senju, Nankodo Co., Ltd. (S44 (1969) 11) Issued monthly)).

<Methods for measuring pH, SS, total iron, ionic iron, and TOC of treated water>

The measurement of pH is performed based on JIS Z 8802 "pH measurement method". The apparatus was a pH meter (manufactured by Horiba Co., Ltd., Model No. D-52) (20°C).

Measurement of TOC is carried out based on JIS K 102 22.1 "Test method for factory drainage organic carbon (TOC)". The apparatus was made into TOC-L (manufactured by SHIMADZU CORPORATION).

The measurement of SS is carried out in accordance with JIS K 102 14.1 "Test method for factory drainage suspended solids". It was suction filtered through a filter, and the weight was determined after drying.

The measurement of total iron is carried out in accordance with JIS K 102 57.4 "Iron (Fe) ICP Emission Spectrometry Method for Factory Drainage Test". The apparatus was 720 ICP-OES (manufactured by Agilent Technologies).

The measurement of ionic iron is carried out in accordance with JIS K 102 57.4 Remarks 14 “Methods for Factory Drainage Test Method for Quantifying Iron (Fe) ICP Emission Spectrometry Method for Dissolved Iron”. The apparatus was a 5110 VDV ICP-OES system (manufactured by Agilent Technologies).

It was measured using a sample filtered with filter paper 5 type C.

[Experimental Example 1]

The contents of each drug used in Experimental Example 1 are shown in Tables 2 and 3. In addition, "special" in the table|surface means "a copolymer crosslinked using a crosslinkable monomer".

The drug cation 7 of Test Example 12 and the drug cation 8 of Test Example 13 are copolymers crosslinked with N,N'-methylenebisacrylamide, respectively. Table 2 shows the results of laboratory evaluation using crude green liquid 1 and each of the drugs 1 to 13, the presence or absence of an ester-bonded cation group to the drug cations 1 to 8, the degree of the cation group, and the presence or absence of a crosslinked structure. Table 3 shows the physical property values of the drugs used.

In Test Examples 1 to 4, the treatment water (crude green liquor) was treated with various anionic polymers (drug anions 1 to 4) alone. In Test Example 5, the water to be treated (crude green liquor) was treated with the positive polymer (drug positive 1 having an ester-bonded cation group) alone. In Test Example 6, the treatment water (crude green liquor) was treated with only the cation polymer having an ester-bonded cation group (drug cation 1).

In Test Examples 7 and 8, water to be treated (crude green liquor) was treated with the chemical cation 2/3 using a cation polymer having an ester-bonded cation group.

In Experimental Examples 9 to 13, water to be treated (crude green liquor) was treated with cations 4 to 8 using a cation polymer having no cation group bonded to an ester bond.

In Test Examples 7 to 13, various cation polymers (drug cations 2 to 8) were further added to the drug anion 2.

As a result of Test Examples 1 to 4, in the treatment of the crude green liquor using anionic polymers (anions 1 to 4), the color tone a* value tended to be high (+60 direction). Drug anion 2 had the lowest a* value among drug anions 1 to 4.

Compared to the treatment with each anion 1 agent (drug anions 1 to 4) (Test Examples 1 to 4), the color tone deteriorated in the treatment with the positive 1 agent (Test Example 5).

In the treatment with the drug cation 1 having an ester-bonded cation group (Test Example 6), a significant improvement in a* value was not observed.

Further, in the treatment by the combined use of the drug cation 2·3 having an ester-bonded cation group and the drug anion 2 (Test Example 7·8), the improvement effect of lowering the color tone a* value of the green liquor was small.

In the drugs 10 to 13 (pharmaceuticals cations 5 to 8) in which the cation group is a quaternary salt without having an ester-bonded cation group, the effect of lowering the color tone a* value of the green liquor is good, and in particular, the drug 12-13 having a crosslinked structure. 13 (drug cation 7·8) showed an excellent effect.

2 is a plot of the results of color tone (a*b*) of green liquor for each drug in Table 2. It was found that in the treatment with anion 1, the a* value was on the right side, but the a* value, which is the color tone of the green liquor, was shifted to the left by the treatment using cations 2 to 8 of the present invention.

From the above, according to the results of Test Examples 9 to 13, it was found that the color tone a* value tended to be lowered in the crude green liquor treatment by use of the drug cations 4 to 8 (direction to -60). In particular, according to the results of Test Examples 7 to 13, it was found that the color tone a* value of the green liquor was improved (in the -60 direction) by the crude green liquor treatment by using a polymer having a quaternary salt as a constituent. By using the chemical cations 4 to 8, a more excellent clarified green liquor could be obtained, and impurities were greatly reduced, and a green liquor of higher quality could be obtained.

[Experimental Example 2]

The contents of each drug used in Experimental Example 2 are shown in Tables 4 and 5. In addition, "special" in the table|surface means "a copolymer crosslinked using a crosslinkable monomer". The drug cation 9 of Test Example 16 is a copolymer crosslinked with N,N'-methylenebisacrylamide. Results of laboratory evaluation using crude green solution 2 and each of the drugs 14 to 19 (anions 2, 6, and cations 9 to 12), and the presence or absence of an ester-bonded cation group to the drug cations 9 to 12, the grade of the cation group, Table 4 shows the presence or absence of a cross-linked structure. Table 5 shows the physical property values of the drugs used.

Experimental Examples 14 and 15 were treated with only the drug anion alone, and Test Examples 16 to 19 were additionally added with various cation polymers (drug cations 9 to 12) to drug anion 6.

In Test Examples 16 to 19 using drugs (cations 9 to 12) having no ester-bonded cation group and having a quaternary cation group, these cations 9 to 12 have an effect of lowering the color a* value of the green liquor. , excellent green liquor clarification effect was exhibited, and a green liquor of higher quality was obtained. Among these, cation 9, which is a crosslinked drug, was able to obtain a more excellent clarified green liquor, and also obtained a green liquor of higher quality with significantly reduced impurities.

[Experimental Example 3: Test Example 20 to Test Example 21]

In the green liquor clarified, in the case of the water quality of the crude green liquor 3 shown in Table 6, the particle size and lime mud of CaCO ₃ generated when the conventional treatment agent (Test Example 20) or the present example agent (Test Example 21) was added The results of the moisture content in the filter are shown in Table 7. In addition, it was measured by the above (measurement method of particle diameter) and (measurement method of moisture content).

In Test Example 21, which is an actual product, improvement in the generation of CaCO ₃ and dehydration of CaCO ₃ as a subsequent step was observed by improving the green liquor treatment.

[Experimental Example 4: Test Example 22]

As shown in Fig. 4 and Table 8, in the green liquor clarifyer, when an anionic polymer (Curifarm PA834, manufactured by Kurita Kogyo Co., Ltd.) is used in combination, it does not have an ester bonded cation group and is a class 4 The change in a* value of the clarification green liquor when the addition amount of the crosslinked cation polymer (drug cation 9) having a salt cation group is changed. The target value of a * value cannot be expressed as an absolute value because it varies depending on the operating conditions of each plant, but at this site, it is judged that the point at which the a * value is almost 0 has become green, and the drug cation 9 from FIG. The amount of addition was estimated to be 8 mg/L.

By increasing the addition amount of the crosslinked cationic polymer having no cationic group in the ester bond, the a* value is lowered, and the color tone of the treated green liquor shifts in the green direction of -60, resulting in an excellent green liquor clarification effect. It was found that the quality of the obtained green liquid was excellent, and it was consistent with the results of the field test.

Therefore, when crude green liquor treatment is performed using a crosslinked cationic polymer agent having no cationic group in an ester bond, the color tone a* value is further improved (in the direction of -60), and a more excellent clarified green liquor can be obtained. In addition, impurities were significantly reduced, and green liquor of higher quality was obtained. In addition, by using the above green liquid, more excellent calcium carbonate could be produced.

1: Pulp manufacturing system
10: digester
11: digester
20: black liquor treatment system
21: evaporator
22: Boiler
30: green liquid clarification (crude green liquid treatment system)
31: dissolution tank (dispersion)
32: Green Liquor Clarifier (Clarification)
33: green liquid tank
40: fire extinguishing and caustic system
41: causticizer
42 : White Liquid Clarifier
43: white liquid tank
44: kiln
411: Slaker
412: causticization reaction tank
45: lime mud filter

Claims (7)

A rust liquid treatment agent containing a cation polymer having no ester-bonded cation groups.
According to claim 1,
The cationic polymer is a polymer having at least a structural unit derived from a cationic monomer having no ester bond,
The cation monomer having no ester bond is an amine monomer not having an ester bond and/or a quaternary ammonium salt monomer having no ester bond.
Green liquor treatment agent.
According to claim 1 or 2,
The cation polymer is a polydiallyldimethylammonium salt and/or a copolymer thereof, an acrylamide/3-acrylamidepropyl(trimethyl)ammonium salt copolymer, an acrylamide/diallyldimethylammonium salt copolymer, and an alkylamine/epichlorohydrin. One or two or more rust liquid treatment agents selected from polycondensates.
A green liquor treatment method in which a cationic polymer having no ester-linked cation groups is added to crude green liquor.
According to claim 4,
The green liquor treatment method wherein the green liquor treatment is green liquor clarification.
A method for producing calcium carbonate, comprising a digestion/causticization step of generating calcium carbonate using a clarified green liquor by adding a cation polymer having no ester-bonded cation group to the crude green liquor.
A green liquor clarification step of clarifying the green liquor by adding a cation polymer having no ester-bonded cation groups to the crude green liquor;
The digestion and causticization process of generating calcium carbonate by digestion and causticization using the green liquor
Calcium carbonate manufacturing method comprising.

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