CA2166458A1 - A process for reducing the content of finely dispersed solids in papermaking process waters - Google Patents
A process for reducing the content of finely dispersed solids in papermaking process watersInfo
- Publication number
- CA2166458A1 CA2166458A1 CA002166458A CA2166458A CA2166458A1 CA 2166458 A1 CA2166458 A1 CA 2166458A1 CA 002166458 A CA002166458 A CA 002166458A CA 2166458 A CA2166458 A CA 2166458A CA 2166458 A1 CA2166458 A1 CA 2166458A1
- Authority
- CA
- Canada
- Prior art keywords
- solids
- content
- water
- flotation
- cationic polymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
- C08F8/30—Introducing nitrogen atoms or nitrogen-containing groups
- C08F8/32—Introducing nitrogen atoms or nitrogen-containing groups by reaction with amines
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
- D21H17/44—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
- D21H17/45—Nitrogen-containing groups
- D21H17/455—Nitrogen-containing groups comprising tertiary amine or being at least partially quaternised
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Water Supply & Treatment (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Hydrology & Water Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Paper (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
In the method proposed, the solids content in the process solutions is reduced by adding measured quantities of special cationic polymers to the process solution and subsequently removing the precipitated solids by flotation and/or filtration.
Description
21 ~6458 English Translation of Article 34 Amendment of April 7, 1995 H 812 PCT/07.04.1995 A process for reducing the c~nt~nt of finely dispersed solids in papel, k;ng process waters Field of the Invention This invention relates to a process for reducing the content of finely dispersed solids in papermaking process waters.
Prior Art Various water-soluble and colloidally dissolved inorganic and organic substances are formed in the production and processing of chemical pulp, mechanical pulp and wastepaper. Other water-soluble substances enter the production circuit with the fresh water, the fillers and chemical auxiliaries. With the growing reduction in the size of the water circuits, the concentration of these substances is undergoing a very considerable increase. This results in additional pollution of the wastewater~ However, far more serious is the disturbing effect on the papermaking process itself. These sub-stances, which are known among experts as "impurities" (cf. for example W. Auhorn, Wo~h~nhl~tt fur Papierfabrikation, 1984, 2, 37-48), can have a serious effect on production, can reduce the effectiveness of the chemical ~l]x;l;~ries and refining agents and can impair paper quality. It is mainly the dissolved organic substances which are an obstacle to any further reduction in the size of the circuits.
In view of the adverse affect of the impurities, water purification is generally necessary in the case of closed water circuits and compact circuits. Flocculation, precipitation, adsorption or flotation processes or combinations thereof are normally used for this purpose (cf. for example J. Schurz, W-orh~nhl~tt fur Papierfabr;~t;nn, 1990, 3, 109-118). Microflotation, for example, is normally used in wash deinking systems. In this process, the suspended solids and the dissolved and colloidal substances are flocculated and then floated out from the water (cf.
for example K. Schnabel, W_~h~nhl~tt fur Papierfa-hrikation~ 1990, 6, 233-237).
Typical flocculants in the treatment of papermaking process waters are inorganic and organic flocculants, such as milk of lime, aluminium or iron salt solutions, cationic polymers, such as polyethyl~n~;m;nP~ cationic starches, polyamidoamine/epichlorohydrin resins and m~l; ' ne/formaldehyde resins (cf. the above-cited articles by W. Auhorn and J. Schurz). A flocculant particularly preferred among experts is polydiallyl dimethylammonium chloride (cf. for example R. Nicke et al., W_ hl~tt fur Papierfabrikation, 1992, 14, 559-564 and the above-cited article by J. Schurz). This compound, which is normally known as poly-DADMAC, is a linear molecule which carries a positive charge at the nitrogen atom in each of the recurring structural units. Towards the outside, this positive charge is neutralized by a negatively charged chloride ion. In overall terms, a polyelectrolyte with a very high charge density is thus formed.
In addition to the water-soluble and colloidally dissolved impurities mentioned aboye, finely dispersed solids also enter papermaking process waters and undesirably accumulate therein at constrictions in the circuit. These solids are, above all, fillers, fine fibers and printing inks. The removal of these unwanted finely dispersed solids is difficult, above all in the presence of dissolved or colloidally dissolved impurities.
Description of the Invention The problem addressed by the present invention was to provide a process for reducing the content of finely dispersed solids in papermaking process waters. In particular, the process according to the invention would not be affected by the presence of dissolved or colloidally dissolved impurities.
It has now been found that special cationic polymers are suitable for the treatment of papermaking circuit waters and wastewaters and are superior in this regard to other cationic polymers known from the prior art.
Accordingly, the present invention relates to a process for reducing the content of finely dispersed solids in process waters of the papermaking industry, a cationic polymer being added to the process water and the flocculated solids being subsequently removed by flotation and/or filtration, characterized in that i) an at least partly water-soluble nitrogen-cont~;n-ng compound with weight average molecular weights of 2,000 to 1,000,000 obt~n~hle by copolymerization of aminofunctional mt~nt ?rs cor-responding to general formula I:
O Rs Rl-CH=CR2-C-Z-(CnH2n)-N (I) in which Rl and R2 are each a hydrogen atom or a methyl group, R3 and R4 are each a hydrogen atom or a Cl_~ alkyl group or a piperazine, piperidine or morpholine group and Rs is a linear or branched Cl_22 alkyl radical, with the proviso that the counterion to the ammonium function is a halogen, sulfate, phosphate, borate or organic acid anion or an electron pair, Z is oxygen or NH and n is a number of 2 to 5, with m~n~ -riC, unsaturated carboxylic acid esters corresponding to general formula III:
R7-CH=CR8-C-o-(CmH2mo)p-R9 tIII) in which R7 and R3 are each a hydrogen atom or a methyl group and R9 is a linear or branched C1_22 alkyl group, m is a number of 2 to 4 and p is a number of 0 to 18, with the proviso that, where p = 0, the content of unsaturated carboxylic acid esters in the copolymer does not exceed 90~ by weight, is used as the cationic polymer and ii) the cationic polymer mentioned in i) is used in a quantity of 1 to 500 mg of active substance per liter of process water.
"At least partly water-soluble" in the context of the present invention means that more than 0.01~ by weight of the copolymers form clear or cloudy solutions in water under in-use conditions.
Finely dispersed solids in the context of the present invention are solids with particle sizes of around 0.1 to 1000 ~m. In the narrower sense, finely dispersed solids are thus fine fibers, fillers and printing inks.
The process according to the invention may be applied with advantage even when the process water in which the content of the finely dispersed solids is to be reduced additionally contains dissolved or colloidally dissolved impurities.
The weight average molecular weights of the cationic polymers to be used in accordance with the invention are preferably in the range from 5,000 to 500,000. The range from 10,000 to 200,000 is most particularly preferred.
In one preferred embodiment of the present invention, the special cationic polymers mentioned are used in a quantity of 5 to 100 mg of active substance per liter of process water.
Suitable aminofunctional m~om~rs corresponding to general formula I are in particular those in which R1 is hydrogen, R7 is hydrogen or methyl, R3 and R4 are methyl or ethyl, Rs represents an electron pair or a C1_4 alkyl group, with the proviso that the counterion to the ammonium function is a halogen anion. Examples are dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethyl; nopropyl methacrylamide, dimethyl~mlnoneopentyl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate and/or methacrylamidopropyl dimethyl~ ;um chloride.
Monomeric unsaturated carboxylic acid esters corresponding to general formula III, in which R9 is preferably a linear or branched C18 alkyl group, include for example ethyl acrylate, methyl methacry-late, butyl acrylate, butyl methacrylate, octyl acrylate and/or anadduct of 3 moles of ethylene oxide with butyl acrylate.
In addition, acrylamide, methacrylamide, N-ethyl acrylamide and/or tert.butyl acrylamide are suitable for copolymerization with aminofunctional m~nom~rs corresponding to general formula I.
The copolymerization of the aminofunctional m~nt ~rs corre-sponding to general formula I is carried out by polymerization processes known per se in aqueous media optionally cont~in;ng water-miscible solvents, such as alcohols, for example isopropanol. The initiator used is a radical-forming substance, for example potassium or ammonium peroxodisulfate, tert.butyl hydroperoxide, azo-bis-(isobutyronitrile), added in small quantities. The copolymerization of the aminofunctional mont- -rs corresponding to general formula I
may be carried out for example by simultaneously adding the ,- om~rs I and the mont_ -rs of general formula III dropwise to water con-t~n;ng the initiator. The polymerization temperature is not criti-cal per se and may vary within wide limits. Temperatures of 60 to 100C can be optimal, depending on the initiator used. Aqueous copolymer solutions with polymer contents of, for example, 10 to 60 by weight are obtained.
sasically, there are no particular limits to either the nature or the origin of the process waters in the process according to the invention. Examples include circuit waters from wash deinking and combined flotation/washing, waters from drainage units of paper ma-chines (tray waters), deckering waters from presses.
In many cases, the extent to which the dispersed solid impurities are removed can be increased by using the special cationic polymers suitable for the purposes of the invention in combination with flotation collectors and/or inorganic adsorbents or flocculants.
In another embodiment, therefore, the present invention relates to combinations of the special cationic polymers mentioned with other flotation collectors and/or inorganic flocculants.
Examples of flotation collectors are C10_22 fatty acids and alkali metal and alkaline earth metal salts thereof, alkoxylated C6_22 alcohols, alkoxylated alkylphenols. The above-mentioned fatty acids and fatty alcohol alkoxylates with a high percentage content of alkylene oxide, more particularly ethylene oxide, are most particu-larly suitable. Examples of flocculants are milk of lime, aluminium or iron salt solutions.
In another preferred embodiment of the present invention, the - ~ 1 6~458 flocculated solids are removed by flotation.
The present invention also relates to the use of the special cationic polymers mentioned above for reducing the content of finely dispersed solids in papermaking process waters. It has been found in this regard that the percentage content of finely dispersed solids is reduced to a distinctly greater extent by the use of the cationic polymers according to the invention than by the use of conventional cationic polymers known from the prior art.
The following Examples are intended to illustrate the invention without limiting it in any way.
~ x a m p 1 e s 1. Substances used Poly-DADMAC: Commercial polydiallyl dimethylammonium chloride;
approx. 40~; average molecular weight 200,000 (a product of Mutek).
Polymer A: The production of this cationic polymer according to the invention was carried out in various batch sizes. The following description of the production process relates to the 1.5 kg labora-tory scale; the percentages by weight of the components in phases a), b) and c) shown below are based on the batch as a whole and, accordingly, add up to 100%.
a) Aqueous phase:
- 59.3 parts by weight of ~ml n~ralized water - 6.5 parts by weight of 30% sulfuric acid - 2.0 parts by weight of acrylic acid b) Organic phase:
- 13.3 parts by weight of dimethylaminoethyl methac-rylate - 2.8 parts by weight of methyl methacrylate - 6.0 parts by weight of isopropanol ~1 66458 c) Initiator solution:
- 10.0 parts by weight of isopropanol - 0.1 part by weight of azo-bis-(isobutyronitrile).
The aqueous phase was introduced into a reactor (reaction vessel equipped with a stirrer, heating system, external cooler, reflux c~n~n~er, internal thermometer and feed mixing vessel). The organic phase was homogenized in a feed mixing vessel and then slowly introduced with stirring into the reactor. The reaction mixture underwent a slight increase in temperature through the exothermic nature of the reaction. The initiator solution was then added at around 30C. The pH value of the mixture was 7.3. The reaction mixture was then carefully heated to 65C by an external heating system. The heat of reaction generated after the start of the reaction was controlled by careful external cooling. After 30 min-utes, the lnt~rn~l temperature of the reaction mixture was increased to 70C and, after another hour, to 80C, the reaction mixture being stirred for another hour at that temperature. A clear, pale yellowish solution with an active substance content of around 20.5 by weight was obtained after cooling.
2. Origin of the impurity-c~nt~ining circuit water A circuit water from a wastepaper recycling plant was used for the tests described below. In addition to the usual stock prepara-tion and the paper machines, the plant had a flotation deinkingsystem.
The circuit water sample required for the tests described below was taken from the stock preparation part of the plant. It had a pH
value of around 8 and, in addition to the unwanted solids, also contained dissolved and colloidally dissolved anionic impurities.
The percentage content of the last-mentioned impurities was deter-mined by the method developed by L. Bley (cf. Wo~h~nhl~tt fur Papierfabr;k~t;~n 1989, 3, page 114) and measured 510-3 mole/l.
Prior Art Various water-soluble and colloidally dissolved inorganic and organic substances are formed in the production and processing of chemical pulp, mechanical pulp and wastepaper. Other water-soluble substances enter the production circuit with the fresh water, the fillers and chemical auxiliaries. With the growing reduction in the size of the water circuits, the concentration of these substances is undergoing a very considerable increase. This results in additional pollution of the wastewater~ However, far more serious is the disturbing effect on the papermaking process itself. These sub-stances, which are known among experts as "impurities" (cf. for example W. Auhorn, Wo~h~nhl~tt fur Papierfabrikation, 1984, 2, 37-48), can have a serious effect on production, can reduce the effectiveness of the chemical ~l]x;l;~ries and refining agents and can impair paper quality. It is mainly the dissolved organic substances which are an obstacle to any further reduction in the size of the circuits.
In view of the adverse affect of the impurities, water purification is generally necessary in the case of closed water circuits and compact circuits. Flocculation, precipitation, adsorption or flotation processes or combinations thereof are normally used for this purpose (cf. for example J. Schurz, W-orh~nhl~tt fur Papierfabr;~t;nn, 1990, 3, 109-118). Microflotation, for example, is normally used in wash deinking systems. In this process, the suspended solids and the dissolved and colloidal substances are flocculated and then floated out from the water (cf.
for example K. Schnabel, W_~h~nhl~tt fur Papierfa-hrikation~ 1990, 6, 233-237).
Typical flocculants in the treatment of papermaking process waters are inorganic and organic flocculants, such as milk of lime, aluminium or iron salt solutions, cationic polymers, such as polyethyl~n~;m;nP~ cationic starches, polyamidoamine/epichlorohydrin resins and m~l; ' ne/formaldehyde resins (cf. the above-cited articles by W. Auhorn and J. Schurz). A flocculant particularly preferred among experts is polydiallyl dimethylammonium chloride (cf. for example R. Nicke et al., W_ hl~tt fur Papierfabrikation, 1992, 14, 559-564 and the above-cited article by J. Schurz). This compound, which is normally known as poly-DADMAC, is a linear molecule which carries a positive charge at the nitrogen atom in each of the recurring structural units. Towards the outside, this positive charge is neutralized by a negatively charged chloride ion. In overall terms, a polyelectrolyte with a very high charge density is thus formed.
In addition to the water-soluble and colloidally dissolved impurities mentioned aboye, finely dispersed solids also enter papermaking process waters and undesirably accumulate therein at constrictions in the circuit. These solids are, above all, fillers, fine fibers and printing inks. The removal of these unwanted finely dispersed solids is difficult, above all in the presence of dissolved or colloidally dissolved impurities.
Description of the Invention The problem addressed by the present invention was to provide a process for reducing the content of finely dispersed solids in papermaking process waters. In particular, the process according to the invention would not be affected by the presence of dissolved or colloidally dissolved impurities.
It has now been found that special cationic polymers are suitable for the treatment of papermaking circuit waters and wastewaters and are superior in this regard to other cationic polymers known from the prior art.
Accordingly, the present invention relates to a process for reducing the content of finely dispersed solids in process waters of the papermaking industry, a cationic polymer being added to the process water and the flocculated solids being subsequently removed by flotation and/or filtration, characterized in that i) an at least partly water-soluble nitrogen-cont~;n-ng compound with weight average molecular weights of 2,000 to 1,000,000 obt~n~hle by copolymerization of aminofunctional mt~nt ?rs cor-responding to general formula I:
O Rs Rl-CH=CR2-C-Z-(CnH2n)-N (I) in which Rl and R2 are each a hydrogen atom or a methyl group, R3 and R4 are each a hydrogen atom or a Cl_~ alkyl group or a piperazine, piperidine or morpholine group and Rs is a linear or branched Cl_22 alkyl radical, with the proviso that the counterion to the ammonium function is a halogen, sulfate, phosphate, borate or organic acid anion or an electron pair, Z is oxygen or NH and n is a number of 2 to 5, with m~n~ -riC, unsaturated carboxylic acid esters corresponding to general formula III:
R7-CH=CR8-C-o-(CmH2mo)p-R9 tIII) in which R7 and R3 are each a hydrogen atom or a methyl group and R9 is a linear or branched C1_22 alkyl group, m is a number of 2 to 4 and p is a number of 0 to 18, with the proviso that, where p = 0, the content of unsaturated carboxylic acid esters in the copolymer does not exceed 90~ by weight, is used as the cationic polymer and ii) the cationic polymer mentioned in i) is used in a quantity of 1 to 500 mg of active substance per liter of process water.
"At least partly water-soluble" in the context of the present invention means that more than 0.01~ by weight of the copolymers form clear or cloudy solutions in water under in-use conditions.
Finely dispersed solids in the context of the present invention are solids with particle sizes of around 0.1 to 1000 ~m. In the narrower sense, finely dispersed solids are thus fine fibers, fillers and printing inks.
The process according to the invention may be applied with advantage even when the process water in which the content of the finely dispersed solids is to be reduced additionally contains dissolved or colloidally dissolved impurities.
The weight average molecular weights of the cationic polymers to be used in accordance with the invention are preferably in the range from 5,000 to 500,000. The range from 10,000 to 200,000 is most particularly preferred.
In one preferred embodiment of the present invention, the special cationic polymers mentioned are used in a quantity of 5 to 100 mg of active substance per liter of process water.
Suitable aminofunctional m~om~rs corresponding to general formula I are in particular those in which R1 is hydrogen, R7 is hydrogen or methyl, R3 and R4 are methyl or ethyl, Rs represents an electron pair or a C1_4 alkyl group, with the proviso that the counterion to the ammonium function is a halogen anion. Examples are dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethyl; nopropyl methacrylamide, dimethyl~mlnoneopentyl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate and/or methacrylamidopropyl dimethyl~ ;um chloride.
Monomeric unsaturated carboxylic acid esters corresponding to general formula III, in which R9 is preferably a linear or branched C18 alkyl group, include for example ethyl acrylate, methyl methacry-late, butyl acrylate, butyl methacrylate, octyl acrylate and/or anadduct of 3 moles of ethylene oxide with butyl acrylate.
In addition, acrylamide, methacrylamide, N-ethyl acrylamide and/or tert.butyl acrylamide are suitable for copolymerization with aminofunctional m~nom~rs corresponding to general formula I.
The copolymerization of the aminofunctional m~nt ~rs corre-sponding to general formula I is carried out by polymerization processes known per se in aqueous media optionally cont~in;ng water-miscible solvents, such as alcohols, for example isopropanol. The initiator used is a radical-forming substance, for example potassium or ammonium peroxodisulfate, tert.butyl hydroperoxide, azo-bis-(isobutyronitrile), added in small quantities. The copolymerization of the aminofunctional mont- -rs corresponding to general formula I
may be carried out for example by simultaneously adding the ,- om~rs I and the mont_ -rs of general formula III dropwise to water con-t~n;ng the initiator. The polymerization temperature is not criti-cal per se and may vary within wide limits. Temperatures of 60 to 100C can be optimal, depending on the initiator used. Aqueous copolymer solutions with polymer contents of, for example, 10 to 60 by weight are obtained.
sasically, there are no particular limits to either the nature or the origin of the process waters in the process according to the invention. Examples include circuit waters from wash deinking and combined flotation/washing, waters from drainage units of paper ma-chines (tray waters), deckering waters from presses.
In many cases, the extent to which the dispersed solid impurities are removed can be increased by using the special cationic polymers suitable for the purposes of the invention in combination with flotation collectors and/or inorganic adsorbents or flocculants.
In another embodiment, therefore, the present invention relates to combinations of the special cationic polymers mentioned with other flotation collectors and/or inorganic flocculants.
Examples of flotation collectors are C10_22 fatty acids and alkali metal and alkaline earth metal salts thereof, alkoxylated C6_22 alcohols, alkoxylated alkylphenols. The above-mentioned fatty acids and fatty alcohol alkoxylates with a high percentage content of alkylene oxide, more particularly ethylene oxide, are most particu-larly suitable. Examples of flocculants are milk of lime, aluminium or iron salt solutions.
In another preferred embodiment of the present invention, the - ~ 1 6~458 flocculated solids are removed by flotation.
The present invention also relates to the use of the special cationic polymers mentioned above for reducing the content of finely dispersed solids in papermaking process waters. It has been found in this regard that the percentage content of finely dispersed solids is reduced to a distinctly greater extent by the use of the cationic polymers according to the invention than by the use of conventional cationic polymers known from the prior art.
The following Examples are intended to illustrate the invention without limiting it in any way.
~ x a m p 1 e s 1. Substances used Poly-DADMAC: Commercial polydiallyl dimethylammonium chloride;
approx. 40~; average molecular weight 200,000 (a product of Mutek).
Polymer A: The production of this cationic polymer according to the invention was carried out in various batch sizes. The following description of the production process relates to the 1.5 kg labora-tory scale; the percentages by weight of the components in phases a), b) and c) shown below are based on the batch as a whole and, accordingly, add up to 100%.
a) Aqueous phase:
- 59.3 parts by weight of ~ml n~ralized water - 6.5 parts by weight of 30% sulfuric acid - 2.0 parts by weight of acrylic acid b) Organic phase:
- 13.3 parts by weight of dimethylaminoethyl methac-rylate - 2.8 parts by weight of methyl methacrylate - 6.0 parts by weight of isopropanol ~1 66458 c) Initiator solution:
- 10.0 parts by weight of isopropanol - 0.1 part by weight of azo-bis-(isobutyronitrile).
The aqueous phase was introduced into a reactor (reaction vessel equipped with a stirrer, heating system, external cooler, reflux c~n~n~er, internal thermometer and feed mixing vessel). The organic phase was homogenized in a feed mixing vessel and then slowly introduced with stirring into the reactor. The reaction mixture underwent a slight increase in temperature through the exothermic nature of the reaction. The initiator solution was then added at around 30C. The pH value of the mixture was 7.3. The reaction mixture was then carefully heated to 65C by an external heating system. The heat of reaction generated after the start of the reaction was controlled by careful external cooling. After 30 min-utes, the lnt~rn~l temperature of the reaction mixture was increased to 70C and, after another hour, to 80C, the reaction mixture being stirred for another hour at that temperature. A clear, pale yellowish solution with an active substance content of around 20.5 by weight was obtained after cooling.
2. Origin of the impurity-c~nt~ining circuit water A circuit water from a wastepaper recycling plant was used for the tests described below. In addition to the usual stock prepara-tion and the paper machines, the plant had a flotation deinkingsystem.
The circuit water sample required for the tests described below was taken from the stock preparation part of the plant. It had a pH
value of around 8 and, in addition to the unwanted solids, also contained dissolved and colloidally dissolved anionic impurities.
The percentage content of the last-mentioned impurities was deter-mined by the method developed by L. Bley (cf. Wo~h~nhl~tt fur Papierfabr;k~t;~n 1989, 3, page 114) and measured 510-3 mole/l.
3. Test procedure 3.1. net~ n~tinn of the solids c~nt~nt in the circuit water A sample of the circuit water emanating from the wastepaper recycling plant was filtered through a paper filter (medium-quick filter rate, mean pore diameter 5.8 ~m), after which the filter was dried for one hour at 90C. The increase in weight of the paper filter is a measure of the finely dispersed solids present in the circuit water. The solids content of the circuit water was found by this method to amount to 0.79 g/l.
3.2. Comparison test 1 A Denver 9 liter laboratory flotation cell was filled with the circuit water sample emanating from the wastepaper recycling plant.
Flotation was carried out over a period of 2 minutes at an air throughput of 200 l/h and at a rotational speed of the stirrer of 1200 min~1. The water from the flotation cell was then filtered through a filter paper as described in 3.1. and the filter was subsequently dried. The solids content of the circuit water was found to be 0.57 g/l. Comparison with the value of 0.79 g/l determined in 3.1. shows that the solids content was reduced by 28 without the addition of an auxiliary, i.e. solely by flotation.
3.3. Comparison test 2 A Denver 9 liter laboratory flotation cell was filled with the circuit water sample emanating from the wastepaper recycling plant.
A dilute aqueous solution of the polymer poly-DADMAC known from the prior art was added in a quantity of 10 mg of poly-DADMAC active sub-stance per liter of circuit water. Flotation was carried out for 2 minutes at an air throughput of 1200 l/h and at a rotational speed of the stirrer of 1200 min~l. The water from the flotation cell was then filtered through a paper filter as described in 3.1. and the filter was subsequently dried. The solids content of the circuit water was found to be 0.31 g/l. Comparison with the value of 0.79 g/l determined under 3.1. shows that the solids content was reduced by 61~ through the addition of poly-DADMAC.
3.4. ~xample 1 (Inv~nt;nn) A Denver g liter laboratory flotation cell was filled with the circuit water sample emanating from the wastepaper recycling plant.
A dilute aqueous solution of polymer A according to the invention was added in a quantity of 10 mg of polymer A active substance per liter of circuit water. Flotation was carried out for 2 minutes at an air throughput of 200 l/h and at a rotational speed of the stirrer of 1200 min~1. The water from the flotation cell was then filtered through a paper filter as described in 3.1. and the filter was subse-quently dried. The solids content of the circuit water was found to be 0.06 g/l. Comparison with the value of 0.79 g/l determined under 3.1. shows that the solids content was reduced by 92~ through addition of polymer A according to the invention.
3.2. Comparison test 1 A Denver 9 liter laboratory flotation cell was filled with the circuit water sample emanating from the wastepaper recycling plant.
Flotation was carried out over a period of 2 minutes at an air throughput of 200 l/h and at a rotational speed of the stirrer of 1200 min~1. The water from the flotation cell was then filtered through a filter paper as described in 3.1. and the filter was subsequently dried. The solids content of the circuit water was found to be 0.57 g/l. Comparison with the value of 0.79 g/l determined in 3.1. shows that the solids content was reduced by 28 without the addition of an auxiliary, i.e. solely by flotation.
3.3. Comparison test 2 A Denver 9 liter laboratory flotation cell was filled with the circuit water sample emanating from the wastepaper recycling plant.
A dilute aqueous solution of the polymer poly-DADMAC known from the prior art was added in a quantity of 10 mg of poly-DADMAC active sub-stance per liter of circuit water. Flotation was carried out for 2 minutes at an air throughput of 1200 l/h and at a rotational speed of the stirrer of 1200 min~l. The water from the flotation cell was then filtered through a paper filter as described in 3.1. and the filter was subsequently dried. The solids content of the circuit water was found to be 0.31 g/l. Comparison with the value of 0.79 g/l determined under 3.1. shows that the solids content was reduced by 61~ through the addition of poly-DADMAC.
3.4. ~xample 1 (Inv~nt;nn) A Denver g liter laboratory flotation cell was filled with the circuit water sample emanating from the wastepaper recycling plant.
A dilute aqueous solution of polymer A according to the invention was added in a quantity of 10 mg of polymer A active substance per liter of circuit water. Flotation was carried out for 2 minutes at an air throughput of 200 l/h and at a rotational speed of the stirrer of 1200 min~1. The water from the flotation cell was then filtered through a paper filter as described in 3.1. and the filter was subse-quently dried. The solids content of the circuit water was found to be 0.06 g/l. Comparison with the value of 0.79 g/l determined under 3.1. shows that the solids content was reduced by 92~ through addition of polymer A according to the invention.
4. Discussion of the results In the interests of clarity, the values obtained in 3.1. to 3.4. are set out in the following Table:
PolymerSolids content (g/l) Reduction in the added solids content Before After flotation flotation - 0.79 0.57 28 Poly-DADMAC 0.79 0.31 61 Polymer A 0.79 0.06 92~
It can clearly be seen that better results are obtained with the cationic polymers according to the invention than with the poly-DADMAC known from the prior art.
PolymerSolids content (g/l) Reduction in the added solids content Before After flotation flotation - 0.79 0.57 28 Poly-DADMAC 0.79 0.31 61 Polymer A 0.79 0.06 92~
It can clearly be seen that better results are obtained with the cationic polymers according to the invention than with the poly-DADMAC known from the prior art.
Claims (7)
1. A process for reducing the content of finely dispersed solids in process waters of the papermaking industry, a cationic polymer being added to the process water and the flocculated solids being subsequently removed by flotation and/or filtration, characterized in that i) an at least partly water-soluble nitrogen-containing compound with weight average molecular weights of 2,000 to 1,000,000 obtainable by copolymerization of aminofunctional monomers cor-responding to general formula I:
(I) in which R1 and R2 are each a hydrogen atom or a methyl group, R3 and R4 are each a hydrogen atom or a C1-4 alkyl group or a piperazine, piperidine or morpholine group and R5 is a linear or branched C1-22 alkyl radical, with the proviso that the counterion to the ammonium function is a halogen, sulfate, phosphate, borate or organic acid anion or an electron pair, Z is oxygen or NH and n is a number of 2 to 5, with monomeric, unsaturated carboxylic acid esters corresponding to general formula III:
(III) in which R7 and R8 are each a hydrogen atom or a methyl group and R9 is a linear or branched C1-22 alkyl group, m is a number of 2 to 4 and p is a number of 0 to 18, with the proviso that, where p = 0, the content of unsaturated carboxylic acid esters in the copolymer does not exceed 90% by weight, is used as the cationic polymer and ii) the cationic polymer mentioned in i) is used in a quantity of 1 to 500 mg of active substance per liter of process water.
(I) in which R1 and R2 are each a hydrogen atom or a methyl group, R3 and R4 are each a hydrogen atom or a C1-4 alkyl group or a piperazine, piperidine or morpholine group and R5 is a linear or branched C1-22 alkyl radical, with the proviso that the counterion to the ammonium function is a halogen, sulfate, phosphate, borate or organic acid anion or an electron pair, Z is oxygen or NH and n is a number of 2 to 5, with monomeric, unsaturated carboxylic acid esters corresponding to general formula III:
(III) in which R7 and R8 are each a hydrogen atom or a methyl group and R9 is a linear or branched C1-22 alkyl group, m is a number of 2 to 4 and p is a number of 0 to 18, with the proviso that, where p = 0, the content of unsaturated carboxylic acid esters in the copolymer does not exceed 90% by weight, is used as the cationic polymer and ii) the cationic polymer mentioned in i) is used in a quantity of 1 to 500 mg of active substance per liter of process water.
2. A process as claimed in claim 1, characterized in that the solids-containing process waters additionally contain dissolved or colloidally dissolved impurities.
3. A process as claimed in claim 1 or 2, characterized in that cationic polymers with weight average molecular weights in the range from 5,000 to 500,000 and preferably in the range from 10,000 to 200,000 are used.
4. A process as claimed in any of claims 1 to 3, characterized in that the cationic polymer is used in a quantity of 5 to 100 mg of active substance per liter of process water.
5. A process as claimed in any of claims 1 to 4, characterized in that the cationic polymer is used in combination with a flotation collector and/or an inorganic flocculant.
6. A process as claimed in any of claims 1 to 5, characterized in that the flocculated solids are removed by flotation.
7. The use of the cationic polymers defined in detail in claims 1 and 2 for reducing the content of finely dispersed solids in process waters of the papermaking industry.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4321819A DE4321819A1 (en) | 1993-07-01 | 1993-07-01 | Process for reducing the content of finely dispersed solids in process water from papermaking |
| DEP4321819.9 | 1993-07-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2166458A1 true CA2166458A1 (en) | 1995-01-12 |
Family
ID=6491636
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002166458A Abandoned CA2166458A1 (en) | 1993-07-01 | 1994-06-22 | A process for reducing the content of finely dispersed solids in papermaking process waters |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0706499B1 (en) |
| JP (1) | JPH08511985A (en) |
| KR (1) | KR960703389A (en) |
| AT (1) | ATE152083T1 (en) |
| CA (1) | CA2166458A1 (en) |
| DE (2) | DE4321819A1 (en) |
| ES (1) | ES2101551T3 (en) |
| FI (1) | FI956346A (en) |
| WO (1) | WO1995001309A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9507895D0 (en) * | 1995-04-18 | 1995-05-31 | Allied Colloids Ltd | Aqueous purification processes |
| DE19532301A1 (en) * | 1995-09-01 | 1997-03-06 | Voith Sulzer Stoffaufbereitung | Process for the preparation of dry waste from a paper, cardboard or coating machine |
| US5750034A (en) * | 1996-11-01 | 1998-05-12 | Nalco Chemical Company | Hydrophilic dispersion polymers for the clarification of deinking process waters |
| US6153049A (en) * | 1998-03-25 | 2000-11-28 | The Dow Chemical Company | Method for inhibiting the deposition of white pitch in paper production using ethylene amine compound |
| DE102005009809B4 (en) * | 2005-03-03 | 2007-02-22 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Process for separating suspended solids |
| CN107442288B (en) * | 2017-08-14 | 2019-08-06 | 江西理工大学 | A kind of morpholine quaternary ammonium salt Gemini surface active for mineral floating |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT571740A (en) * | 1956-04-10 | |||
| DE1179098B (en) * | 1961-05-03 | 1964-10-01 | Basf Ag | Flotation agent for clarifying waste water containing paper fibers |
-
1993
- 1993-07-01 DE DE4321819A patent/DE4321819A1/en not_active Withdrawn
-
1994
- 1994-06-22 WO PCT/EP1994/002038 patent/WO1995001309A1/en active IP Right Grant
- 1994-06-22 AT AT94921619T patent/ATE152083T1/en active
- 1994-06-22 DE DE59402545T patent/DE59402545D1/en not_active Expired - Fee Related
- 1994-06-22 ES ES94921619T patent/ES2101551T3/en not_active Expired - Lifetime
- 1994-06-22 KR KR1019950706003A patent/KR960703389A/en not_active Application Discontinuation
- 1994-06-22 CA CA002166458A patent/CA2166458A1/en not_active Abandoned
- 1994-06-22 EP EP94921619A patent/EP0706499B1/en not_active Expired - Lifetime
- 1994-06-22 JP JP7503243A patent/JPH08511985A/en active Pending
-
1995
- 1995-12-29 FI FI956346A patent/FI956346A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| FI956346A0 (en) | 1995-12-29 |
| KR960703389A (en) | 1996-08-17 |
| FI956346A (en) | 1996-02-19 |
| JPH08511985A (en) | 1996-12-17 |
| ATE152083T1 (en) | 1997-05-15 |
| ES2101551T3 (en) | 1997-07-01 |
| DE4321819A1 (en) | 1995-01-12 |
| WO1995001309A1 (en) | 1995-01-12 |
| DE59402545D1 (en) | 1997-05-28 |
| EP0706499B1 (en) | 1997-04-23 |
| EP0706499A1 (en) | 1996-04-17 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Discontinued |