CA2213367A1 - Enhanced removal of hydrophobic contaminants from water clarification systems - Google Patents
Enhanced removal of hydrophobic contaminants from water clarification systemsInfo
- Publication number
- CA2213367A1 CA2213367A1 CA 2213367 CA2213367A CA2213367A1 CA 2213367 A1 CA2213367 A1 CA 2213367A1 CA 2213367 CA2213367 CA 2213367 CA 2213367 A CA2213367 A CA 2213367A CA 2213367 A1 CA2213367 A1 CA 2213367A1
- Authority
- CA
- Canada
- Prior art keywords
- polymer
- stickies
- secondary fiber
- paper mill
- daf
- 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
Links
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
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
- D21C5/02—Working-up waste paper
- D21C5/022—Chemicals therefor
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/08—Removal of fats, resins, pitch or waxes; Chemical or physical purification, i.e. refining, of crude cellulose by removing non-cellulosic contaminants, optionally combined with bleaching
- D21C9/086—Removal of fats, resins, pitch or waxes; Chemical or physical purification, i.e. refining, of crude cellulose by removing non-cellulosic contaminants, optionally combined with bleaching with organic compounds or compositions comprising organic compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/26—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof
- C02F2103/28—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof from the paper or cellulose industry
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/64—Paper recycling
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S210/00—Liquid purification or separation
- Y10S210/928—Paper mill waste, e.g. white water, black liquor treated
Abstract
The present invention provides a method for removing secondary fiber contaminants from paper mill process waters comprising adding a polyvinyl chloride, a cationic polymeric coagulant and a polymeric flocculant to paper mill process waters containing secondary fiber contaminants in an amount sufficient to agglomerate the secondary fiber contaminants to larger particles sizes, and removing the secondary fiber contaminants from the process water by a dissolved air flotation clarification technique. The addition of particulate polyvinyl chloride in combination with a polymeric coagulant and flocculant prior to the DAF clarification process causes the contaminants to become preferentially coated with the polyvinyl chloride particles.
This coating is what causes the subsequent removal of the secondary fiber contaminants in the DAF clarification process to be more effective.
This coating is what causes the subsequent removal of the secondary fiber contaminants in the DAF clarification process to be more effective.
Description
,, R~ v. uund ûf the Invention 1. Field of the Invention The present invention generally relates to a method for removing secondary fiber5 cont~min~nt~ from paper mill process waters. More particularly, it relates to the removal of secondary fiber con~ using a polyvinyl chloride in co~ alion with a co~ nt and a flocculant to agglomerate the fiber co,-l~".in~.~l, such that the co.~l~....l-~..ls may be more efficiently removed by dissolved air flotation clarification.
2. DescriPtion of the Prior Art 1C The problem of secondary fiber col,l~.. ;.. ~,.l ("stickies") control in papermaking processes has previously been recognized for all types of paperrnaking processes.
Problems associated with stickies occur during the repulping and reuse of secondary fiber which contains materials such as (1) labels and envelopes with pressure sensitive adhesives such as styrene butadiene rubber and vinyl acrylates, (2) book and m~7ine bi~ldings co.ll~il-il-g hot melt glues such as vinyl acetate polymers, (3) old corrugated containers or produce boxes with petroleum wax or polyethylene coatings, and (4) materials which contain pac~ in~ and other types of tape. During repulping, these secondary fiber cont~min~nts sometimes remain associated with the fibers, but more often are released from the fibers and dispersed as small adhesive particles in the aqueous pulp slurry.
Stickies, being primarily hydrophobic, deforrnable and tacky by nature, will often agglomerate to forrn larger hydrophobic particles in the aqueous system of the papermaking process, resulting in numerous product quality and paper m~.hine operational problems. Stickies frequently deposit on various components of the papermaking equipment, such as conci~t~ncy regulators, screens, headboxes, wires, foils, Uhle boxes, rolls, felts, dryers and calendar rolls.
Such deposition often causes reduced or lost paper m~.hin~ production and excessive downtime for clean-up of deposits. Such deposition also causes inferior paper quality rçsl-lting from specks, defects, holes, tears and breaks in the sheet. Stickies are typically pliable and frequently have the same specific gravity as water and fiber, thus they are often .liffic~lt to separate from the pulp by mechanical operations such as screening and centrifugal cleaning. In paper mills that recycle their process water as well as use secondary fiber as a furnish source, problems due to stickie contaminants can be even more serious. In recycled process waters, stickies recirculate and "cycle up" in concentration, eventually causing system purges which lead to severe deposit and runnability problems.
Wood pitch is the tacky, resinous material which is released from wood in the form of a colloidal, oil-in-water dispersion during pulping. Typical wood pitch col,lponellls include fatty acids, resin acids, triglyceride esters and other fats, waxes, fatty alcohols and hydrocarbons.
15 White pitch is a term which refers to the polymeric latex binders found in paper coatings. Typical coating binders include polyvinyl acetates and styrene butadience resins. Stickies, wood pitch, white pitch and other hydrophobic materials typically found in papermaking processes (e.g.
defoamers, sizing agents, wet strength resins) will typically associate, agglomerate and co-deposit as they come into contact with each other in the papermaking process streams.
Paper mills that deink recycled fiber and/or recycle their process water often employ dissolved air flotation (DAF) clarifiers to remove ink, stickies, pitch and other suspended solids CA 022l3367 l997-08-l9 (e.g. fiber fines, clay, dirt, etc.) from this water. Polymeric co~llAntc and floccl.lAntc are sometimes added to DAF influent streams to aid in the removal of such co"lh.";"~ c from the process waters entering the DAF clarifiers.
Summars~ of the Invention s The present invention provides a method for removing secondary fiber co.. l~.. ;.. ~.. lc from paper mill process waters comprising adding a polyvinyl chloride, a cationic polymeric coA~ nt and a polymeric flocculant to paper mill process waters co. l~ g secondary fiber co..lA...;nA.~Is in an amount sufficient to agglomerate the secondary fiber co..l;l...;nA..I~ to larger particles sizes, and removing the secondary fiber co..l~ A..Ic from the process water by a dissolved air flotation 10 clarification technique. The addition of particulate polyvinyl chloride in co"lbina~ion with a polymeric coaEul~nt and flocculant prior to the DAF clarification process causes the co~ .lls to become preferentially coated with the polyvinyl chloride particles. This coating is what causes the subsequent removal ofthe secondary fiber contA.~.;n~.~ls in the DAF clarification process to be more effective.
Description of the Preferred E~mbodiments The present invention pertains to the use of polyvinyl chloride as a novel agglomerating agent for use in removing secondary fiber contAmin~nts from paper mill process waters. The preferred method for removal of secondary fiber cont~minAnt.c from paper mill process waters comprises adding a polyvinyl chloride, a cationic polymeric co~ nt and a polyrneric flocculant to paper mill process waters cont~ining secondary fiber co~ AI~tc (so-called "stickies") in an amount sufficient to agglomerate the cont~min~ntc to larger particle sizes, and removing the contaminants by dissolved air flotation clarification.
The agglomeration is preferably conducted at a temperature in the range between about 70~F. to about 160~F., more preferably from about 100~F. to about 140~F.
Preferably in the method polyvinyl chloride is added to the process waters in an amount between about 10 parts per million and about 100 parts per mlllion. Also preferably the cationic polymeric coagulant is added to the process waters in an amount between about 1 part and 50 parts per million.
Additionally the polymeric flocculant is added in amounts of between about 1 part and 25 parts per milllon. All parts are parts per million volume of paper mlll process water.
The present invention provides a method of agglomeratlon of secondary flber contamlnants to larger partlcle sizes that permlt the separation of such contaminants by a dissolved air flotation clarificatlon technlque whlch would be insufficient if employed on untreated influent process water.
Thus, the present invention provides a method whereby both small and large stickie particles are removed from the paper mill process water.
The DAF influent process water generally should be under at least some degree of mechanical agitatlon at the time of treatment by the addition of the polyvinyl chloride thereto and a time period thereafter. As a general guidellne, the mechanical agitation should be of a sufficient rate and time duration to achieve satisfactory mixlng of the DAF influent process in order to form the chemically modified agglomerates of secondary fiber contaminants.
Examples In the examples given below, several polymers are compared for efficacy and compatibility. Polymer A is a particulate polyvinyl chloride, with an average particle diameter of ~170 microns and a specific gravlty of 1.4. Polymer B is an acrylamide/acrylate anionic flocculant, 69 mole percent, RSV = 46-56 dl/g. Polymer C is an acrylamide/acrylate anionic flocculant, 29 mole percent, RSV = 41-54 dl/g. Polymer D is an acrylamide/DMAEA.MCQ cationic flocculant, 10 mole percent, RSV = 21-30 dl/g. Finally, Polymer E is a "linear"
EPI-DMA cationic coagulant, with an intrinsic viscosity (I.V.)=0.15-0.29 dl/g.
5a CA 022l3367 l997-08-l9 Example 1 Laboratory stickies removal testing was performed on DAF influent process water from a Northeastern U. S. paper mill. The purpose of this testing was to determine whether Polymer A, a polyvinyl chloride, was a good stickies removal agent when used in conjunction with DAF
polymers.
Simple screening tests were done first to identify the most effective co~ nt and flocculant. Of the three floccul~nt.~ tested: Polymer B, Polymer C and Polymer D; Polymer D
exhibited the best activity. Polymer E was most effective in conjunction with Polymer D. The optimum dosages were 80 ppm Polymer E and 60 ppm Polymer D. Testing was performed using 1C a gang stirrer (6 sample capacity). The DAF influent water from the Northeastern paper mill was allowed to come to room temperature and was mixed at ~400 rpm to keep sampling comi~tçnt.
800 mL aliquots were transferred to 1 liter beakers. The water in the beakers was mixed on the gang stirrer at ~100 rpm for 1 minute. The proper dosage of Polymer E was then added, and the mixing speed was increased to ~200 rpm for 30 seconds. At 30 seconds, Polymer D was added and mixing speed was decreased to ~100 rpm. Mixing continued for 2 mimltes. The samples were allowed to settle and 20 ml aliquots were taken for turbidity readings.
Once the optimum DAF polymer dosages were determined, a dosage profile using Polymer A was performed. The procedure was the same as above, except that Polymer A was added to the sample first, and mixed for I minute at ~100 rpm. The proper dosage of Polymer D
was then added, and the mixing speed was increased to ~200 rpm for 30 seconds. Polymer C was then added and the mixing speed was decreased to ~100 rpm. Mixing continued for 1 minute.
CA 022l3367 l997-08-l9 The samples were allowed to settle and 20 ml aliquots were taken for turbidity re~in~c The following tests were performed:
A. "Control" - no tre~tm~nt;
B. "Polymer A Only" - 2, 20 and S0 ppm Polymer A without DAF polymers;
s C. "Polymer D spiked with Polymer A" - 20 ppm Polymer A was added to the made-down Polymer D;
D. "Polymer A/Polymer E/Polymer D" - Polymer A was added at 2, 20 and 50 ppm prior to the addition of the Polymer E and Polymer D.
In all tests where Polymer E and Polymer D were used, the polymers were dosed at 80 10 ppm and 60 ppm respectively. (For the "Polymer A Only" testing: Polymer A was added at ~200 rpm, mixed for 30 seconds, and the speed decreased to ~100 rpm for an additional 2.5 minlltes).
The samples from all of the tests were allowed to settle and 20 ml aliquots were taken for turbidity readings. The samples were then filtered through a Britt-Jar screen. The solids/particulates re".~ ;ng on the screen were washed offonto Whatman 41 filter paper using vacuum filtration. The filter paper was placed in a h~ndcheet mold and allowed to dry overnight.
The solids/particulates on the filter papers were then ex;1.,.;l-ed microscopically.
The "Control" (no treatment) had several stickies. The "Polymer E/Polymer D Only"
samples also showed several stickies. The "Polymer A Only" samples showed a few stickies and several unattached Polymer A particles. The "Polymer A/Polymer E/Polymer D" samples showed that the Polymer A particles were attached to the stickies. All samples with Polymer A had excess unattached Polymer A particles in the effluent, which would be a reason for the increase in CA 022l3367 l997-08-l9 turbidity seen with the addition of Polymer A.
Example 2 Additional lab work was done to evaluate the effectiveness of Polymer A using the Northeastern U.S. paper mill's DAF operating conditions.
Simple screening tests were performed first to identify the most effective dosages of Polymer E and Polymer B. The DAF influent water from the was mixed at ~400 rpm to keep sampling con~i~tçnt 400 mL aliquots were ll~lsrelled to 600 ml beakers. The water in the beakers was mixed on the gang stirrer at ~100 rpm for 1 minute. Polymer E was then added, and the mixing speed was increased to ~200 rpm for 30 seconds. At 30 seconds, Polymer B was 10 added and the mixing speed was decreased to ~100 rpm. Mixing continued for 1 minute. The samples were allowed to settle and 20 ml aliquots were taken for turbidity rearlin~.c.
Once an optimum Polymer B/Polymer E dosage was dete....i..ed, a profile using Polymer A was performed. The procedure was the same as above, except that Polymer A was added to the sample first, and mixed for 1 minute at ~100 rpm. The proper dosage of Polymer E was then added, and the mixing speed was increased to ~200 rpm for 30 seconds. Polymer B was then added and the mixing speed was decreased to ~100 rpm. Mixing continued for 1 minute. The contents of the beaker were allowed to settle and 20 ml aliquots taken for turbidity reading~. The 20 ml aliquot was then returned to its original beaker and the contents of the beaker was slowly poured into a 1 liter graduated cylinder for DAF clarification ~im~ tion tests.
To simulate DAF air injection, 100 ml of pressurized (50 psi) deionized water was added to the water sample via a wand inserted to the bottom of grad~l~ted cylinder. This technique introduces micro-bubbles of dissolved air. As soon as 100 ml of pressurized deionized water was added to the cylinder, a timer was started to determlne the length of time it took for the solids (l.e. pulp fines, ash, stickies, etc.) to form a mat at the surface.
The water underneath the mat is called the DAF effluent for purposes of describing the invention. The DAF effluent was drained, via a valve at the bottom of the cylinder, from the cylinder. A 20 ml aliquot of the effluent was taken for a turbidity reading. Since the micro-bubbles from the simulated DAF process interfered with turbidlty readings, the 20 ml aliquot was placed in an ultrasonic water bath for 5 minutes to remove the micro-bubbles. The mat from the simulated DAF air iniection was filtered through a 40 ~m screen using gravity filtration.
Any particles remaining on the screen were then rinsed onto Whatman 41 filter paper and dried in drying rings overnight.
To obtain a total stickles count via image analysis, the effluent was drained from the cylinder and filtered through a 40 ~m screen. A clean Whatman 41 filter paper was placed on top of the particulate covered filter paper and pressed with a 300~F
iron for 2 minutes. The two filter papers were then carefully separated, and anything adhering to the top filter paper was counted as a stickie. Image analysis was utilized to quantify the stickies adhering to the top filter paper.
Image analysis is a method used to quantify both dirt and stickies in handsheets. Image analysis can detect either dark partlcles on a light background (dirt count) or light particles on a dark background (stickies analysis). A reverse dye method is used to quantify light partlcles on a dark back-ground. This method is outlined in an article by M. P. Hacker, TAPPIJ. 75 (7), 63, 1992. This method is performed by dyeing 9a CA 022l3367 l997-08-l9 the handsheets with a dark colored water-soluble dye. Stickies, being primarily hydrophobic in nature, will not accept this dye. This leaves a light colored area which can be measured through image analysis in the reverse polarity mode. Some stickies are naturally dark in color; stickies of this kind are in~ ded in the dirt count data.
With the image analysis stickies/dirt data, a percent stickies/dirt removal efficiency (%
SDRE) was calculated. Calculation of percent stickies/dirt removal is as follows:
%SDRE = Total count of untreated effluent - Total count of treated effluent Total count of untreated effluent 10 Where: Total count of untreated effluent = dirt count + stickies count for untreated effluent Total count of treated effluent = dirt count + stickies count for treated effluent Note: Stickies can pick up dark colored inks in the papel.llaking process and thus appear dark in color. For this reason, both dirt (dark particles on a light background) and stickies (light particles on a dark background) counts were in~ ded in the total counts for the treated and untreated effluents.
The Polymer B/Polymer E/Polymer A program worked very well in the lab on stickies removal. The Polymer B/Polymer E/Polymer A program had a 92.2% stickies/dirt removal efficiency and the Polymer B/Polymer E program had a stickies/dirt removal efficiency of 45.1%.
The clarity of the DAF effluent was much better with the Polymer B/Polymer E/Polymer A
program (23 NTU) than with the Polymer B/Polymer E program (72 NTU) and both treatment programs were better than the untreated DAF effluent (84 NTU).
ExamPle 3 A short trial was run at a Northeastern U.S. paper mill to enh~nce stickies removal in the DAF clarification system through the incorporation of Polymer A in the Polymer B/Polymer E
DAF polymer program. A stickies removal efficiency of up to 98.9% was achieved during the trial.
The trial was run to address a stickies/pitch/wax problem in the mill. The mill has two DAF clarifiers. One is an "effluent only" clarifier, where the accepts are sewered. The other is a "process" clarifier, where the accepts are recirculated back to the pap~""~rlline process water.
The mill was interested in a DAF chemical l,~l ",~.,l program that would decrease the amount of 10 stickies/pitch/wax that carried over to the paperm~rhine process water. Polymer treatm~ntc as described in Example 2 above were evaluated.
To determine the effectiveness of the trial, h~ntlcheetc were made for stickies analysis and colloidal pitch counts were performed on the DAF influent and çfflu~nt Colloidal pitch counts were performed using a microscope and a hemacytometer: 21.1 x 107 pitch particles/ml were obtained with 5 ppm Polymer E/8 ppm Polymer B, 4.4 x 107 pitch particles/ml were obtained with l S ppm Polymer E/20 ppm Polymer B, and 2. 8 x 107 pitch particles/ml were obtained with 15 ppm Polymer E/20 ppm Polymer B/90 ppm Polymer A. There was a significant decrease in the colloidal pitch counts with the addition of Polymer A to the treatm~nt For stickies analysis, 500 ml of sample was filtered through a 200 mesh (76~1m) Britt Jar screen. The sample was washed with three liters of water to be certain all of the fibers were washed through the screen. The particles on the screen were then washed onto Whatman 41 filter CA 022l3367 l997-08-l9 paper. The filter paper was removed and the side with the particles was joined with a clean filter paper. The two filter papers were pressed together using a 300~F iron for 2 minl~tçC~. The filter papers were then carefully separated, and any particles adhering to the top filter pad were counted as stickies.
Some of the particles adhering to the top filter paper were dark in color. These particles were counted with image analysis and were recorded as "dark" stickies. Other particles on the top filter paper were white in color or transparent. Since image analysis can only detect particles that have some contrast to the background, the top filter paper was dyed with a dark colored water soluble dye. Stickies, being primarily hydrophobic in nature, do not adsorb this dye. This 1O leaves a light colored particle area which can be measured with image analysis techniques. This measurement was recorded as "light" stickies.
With the image analysis data, a percent stickies removal efficiency (%SRE) was calculated. Calculation of percent stickies removal was as follows:
% SRE = Total count feed - Total count X 100 Total count offeed Where: Total count feed = Total stickies count of the feed Total count accepts = Total stickies count of the accepts The stickies removal efficiency (SRE) with 5 ppm Polymer E and 8 ppm Polymer B was 63 . 7%. Polymer B/Polymer E/Polymer A dosages were altered throughout the trial to determine the most efficient program. The most efficient program for stickies removal was with 15 ppm Polymer E/20 ppm Polymer B/90 ppm Polymer A. This program col"billalion yielded a 98.9%
stickies removal efficiency. With the 15 ppm Polymer E/20 ppm Polymer B program alone the SRE was 71.4%.
The use of Polymer A in co",bhlalion with the Polymer E coa~ nt/Polymer B flocculant program proved to be highly effective in increasing the stickies removal efficiency in the DAF
clarification system.
Example 4 A 30 day trial was run at the same Northeastem U.S. paper mill to çnh~nce stickies removal in the DAF clarification system through the incorporation of Polymer A in the existing Polymer E/Polymer B DAF polymer program. Using the analysis techniques described in 1C Example 3, a stickies removal efficiency of up to 98.9% was achieved during the trial.
The stickies removal efficiency (SRE) with 10 ppm Polymer E and 8 ppm Polymer B was 33.3%. Polymer E/Polymer B/Polymer A dosages were altered throughout the trial to determine the most efficient program. The most efficient program for stickies removal was with 18 ppm Polymer E/13 ppm Polymer B/80 ppm Polymer A. This program co",bil,alion yielded a 98.9%
stickies removal efficiency. With a 15 ppm Polymer E/13 ppm Polymer B program alone, the SRE was 88.4%.
The use of Polymer A in combination with the Polymer E coa~ nt/Polymer B flocculant program proved to be highly effective in increasing the stickies removal efficiency in the DAF
clarification system.
Changes can be made in the composition, operation and arrangement of the method and the polymers of the present invention described herein without dep~ l;llg from the concept and scope ofthe invention as defined in the following claims:
Problems associated with stickies occur during the repulping and reuse of secondary fiber which contains materials such as (1) labels and envelopes with pressure sensitive adhesives such as styrene butadiene rubber and vinyl acrylates, (2) book and m~7ine bi~ldings co.ll~il-il-g hot melt glues such as vinyl acetate polymers, (3) old corrugated containers or produce boxes with petroleum wax or polyethylene coatings, and (4) materials which contain pac~ in~ and other types of tape. During repulping, these secondary fiber cont~min~nts sometimes remain associated with the fibers, but more often are released from the fibers and dispersed as small adhesive particles in the aqueous pulp slurry.
Stickies, being primarily hydrophobic, deforrnable and tacky by nature, will often agglomerate to forrn larger hydrophobic particles in the aqueous system of the papermaking process, resulting in numerous product quality and paper m~.hine operational problems. Stickies frequently deposit on various components of the papermaking equipment, such as conci~t~ncy regulators, screens, headboxes, wires, foils, Uhle boxes, rolls, felts, dryers and calendar rolls.
Such deposition often causes reduced or lost paper m~.hin~ production and excessive downtime for clean-up of deposits. Such deposition also causes inferior paper quality rçsl-lting from specks, defects, holes, tears and breaks in the sheet. Stickies are typically pliable and frequently have the same specific gravity as water and fiber, thus they are often .liffic~lt to separate from the pulp by mechanical operations such as screening and centrifugal cleaning. In paper mills that recycle their process water as well as use secondary fiber as a furnish source, problems due to stickie contaminants can be even more serious. In recycled process waters, stickies recirculate and "cycle up" in concentration, eventually causing system purges which lead to severe deposit and runnability problems.
Wood pitch is the tacky, resinous material which is released from wood in the form of a colloidal, oil-in-water dispersion during pulping. Typical wood pitch col,lponellls include fatty acids, resin acids, triglyceride esters and other fats, waxes, fatty alcohols and hydrocarbons.
15 White pitch is a term which refers to the polymeric latex binders found in paper coatings. Typical coating binders include polyvinyl acetates and styrene butadience resins. Stickies, wood pitch, white pitch and other hydrophobic materials typically found in papermaking processes (e.g.
defoamers, sizing agents, wet strength resins) will typically associate, agglomerate and co-deposit as they come into contact with each other in the papermaking process streams.
Paper mills that deink recycled fiber and/or recycle their process water often employ dissolved air flotation (DAF) clarifiers to remove ink, stickies, pitch and other suspended solids CA 022l3367 l997-08-l9 (e.g. fiber fines, clay, dirt, etc.) from this water. Polymeric co~llAntc and floccl.lAntc are sometimes added to DAF influent streams to aid in the removal of such co"lh.";"~ c from the process waters entering the DAF clarifiers.
Summars~ of the Invention s The present invention provides a method for removing secondary fiber co.. l~.. ;.. ~.. lc from paper mill process waters comprising adding a polyvinyl chloride, a cationic polymeric coA~ nt and a polymeric flocculant to paper mill process waters co. l~ g secondary fiber co..lA...;nA.~Is in an amount sufficient to agglomerate the secondary fiber co..l;l...;nA..I~ to larger particles sizes, and removing the secondary fiber co..l~ A..Ic from the process water by a dissolved air flotation 10 clarification technique. The addition of particulate polyvinyl chloride in co"lbina~ion with a polymeric coaEul~nt and flocculant prior to the DAF clarification process causes the co~ .lls to become preferentially coated with the polyvinyl chloride particles. This coating is what causes the subsequent removal ofthe secondary fiber contA.~.;n~.~ls in the DAF clarification process to be more effective.
Description of the Preferred E~mbodiments The present invention pertains to the use of polyvinyl chloride as a novel agglomerating agent for use in removing secondary fiber contAmin~nts from paper mill process waters. The preferred method for removal of secondary fiber cont~minAnt.c from paper mill process waters comprises adding a polyvinyl chloride, a cationic polymeric co~ nt and a polyrneric flocculant to paper mill process waters cont~ining secondary fiber co~ AI~tc (so-called "stickies") in an amount sufficient to agglomerate the cont~min~ntc to larger particle sizes, and removing the contaminants by dissolved air flotation clarification.
The agglomeration is preferably conducted at a temperature in the range between about 70~F. to about 160~F., more preferably from about 100~F. to about 140~F.
Preferably in the method polyvinyl chloride is added to the process waters in an amount between about 10 parts per million and about 100 parts per mlllion. Also preferably the cationic polymeric coagulant is added to the process waters in an amount between about 1 part and 50 parts per million.
Additionally the polymeric flocculant is added in amounts of between about 1 part and 25 parts per milllon. All parts are parts per million volume of paper mlll process water.
The present invention provides a method of agglomeratlon of secondary flber contamlnants to larger partlcle sizes that permlt the separation of such contaminants by a dissolved air flotation clarificatlon technlque whlch would be insufficient if employed on untreated influent process water.
Thus, the present invention provides a method whereby both small and large stickie particles are removed from the paper mill process water.
The DAF influent process water generally should be under at least some degree of mechanical agitatlon at the time of treatment by the addition of the polyvinyl chloride thereto and a time period thereafter. As a general guidellne, the mechanical agitation should be of a sufficient rate and time duration to achieve satisfactory mixlng of the DAF influent process in order to form the chemically modified agglomerates of secondary fiber contaminants.
Examples In the examples given below, several polymers are compared for efficacy and compatibility. Polymer A is a particulate polyvinyl chloride, with an average particle diameter of ~170 microns and a specific gravlty of 1.4. Polymer B is an acrylamide/acrylate anionic flocculant, 69 mole percent, RSV = 46-56 dl/g. Polymer C is an acrylamide/acrylate anionic flocculant, 29 mole percent, RSV = 41-54 dl/g. Polymer D is an acrylamide/DMAEA.MCQ cationic flocculant, 10 mole percent, RSV = 21-30 dl/g. Finally, Polymer E is a "linear"
EPI-DMA cationic coagulant, with an intrinsic viscosity (I.V.)=0.15-0.29 dl/g.
5a CA 022l3367 l997-08-l9 Example 1 Laboratory stickies removal testing was performed on DAF influent process water from a Northeastern U. S. paper mill. The purpose of this testing was to determine whether Polymer A, a polyvinyl chloride, was a good stickies removal agent when used in conjunction with DAF
polymers.
Simple screening tests were done first to identify the most effective co~ nt and flocculant. Of the three floccul~nt.~ tested: Polymer B, Polymer C and Polymer D; Polymer D
exhibited the best activity. Polymer E was most effective in conjunction with Polymer D. The optimum dosages were 80 ppm Polymer E and 60 ppm Polymer D. Testing was performed using 1C a gang stirrer (6 sample capacity). The DAF influent water from the Northeastern paper mill was allowed to come to room temperature and was mixed at ~400 rpm to keep sampling comi~tçnt.
800 mL aliquots were transferred to 1 liter beakers. The water in the beakers was mixed on the gang stirrer at ~100 rpm for 1 minute. The proper dosage of Polymer E was then added, and the mixing speed was increased to ~200 rpm for 30 seconds. At 30 seconds, Polymer D was added and mixing speed was decreased to ~100 rpm. Mixing continued for 2 mimltes. The samples were allowed to settle and 20 ml aliquots were taken for turbidity readings.
Once the optimum DAF polymer dosages were determined, a dosage profile using Polymer A was performed. The procedure was the same as above, except that Polymer A was added to the sample first, and mixed for I minute at ~100 rpm. The proper dosage of Polymer D
was then added, and the mixing speed was increased to ~200 rpm for 30 seconds. Polymer C was then added and the mixing speed was decreased to ~100 rpm. Mixing continued for 1 minute.
CA 022l3367 l997-08-l9 The samples were allowed to settle and 20 ml aliquots were taken for turbidity re~in~c The following tests were performed:
A. "Control" - no tre~tm~nt;
B. "Polymer A Only" - 2, 20 and S0 ppm Polymer A without DAF polymers;
s C. "Polymer D spiked with Polymer A" - 20 ppm Polymer A was added to the made-down Polymer D;
D. "Polymer A/Polymer E/Polymer D" - Polymer A was added at 2, 20 and 50 ppm prior to the addition of the Polymer E and Polymer D.
In all tests where Polymer E and Polymer D were used, the polymers were dosed at 80 10 ppm and 60 ppm respectively. (For the "Polymer A Only" testing: Polymer A was added at ~200 rpm, mixed for 30 seconds, and the speed decreased to ~100 rpm for an additional 2.5 minlltes).
The samples from all of the tests were allowed to settle and 20 ml aliquots were taken for turbidity readings. The samples were then filtered through a Britt-Jar screen. The solids/particulates re".~ ;ng on the screen were washed offonto Whatman 41 filter paper using vacuum filtration. The filter paper was placed in a h~ndcheet mold and allowed to dry overnight.
The solids/particulates on the filter papers were then ex;1.,.;l-ed microscopically.
The "Control" (no treatment) had several stickies. The "Polymer E/Polymer D Only"
samples also showed several stickies. The "Polymer A Only" samples showed a few stickies and several unattached Polymer A particles. The "Polymer A/Polymer E/Polymer D" samples showed that the Polymer A particles were attached to the stickies. All samples with Polymer A had excess unattached Polymer A particles in the effluent, which would be a reason for the increase in CA 022l3367 l997-08-l9 turbidity seen with the addition of Polymer A.
Example 2 Additional lab work was done to evaluate the effectiveness of Polymer A using the Northeastern U.S. paper mill's DAF operating conditions.
Simple screening tests were performed first to identify the most effective dosages of Polymer E and Polymer B. The DAF influent water from the was mixed at ~400 rpm to keep sampling con~i~tçnt 400 mL aliquots were ll~lsrelled to 600 ml beakers. The water in the beakers was mixed on the gang stirrer at ~100 rpm for 1 minute. Polymer E was then added, and the mixing speed was increased to ~200 rpm for 30 seconds. At 30 seconds, Polymer B was 10 added and the mixing speed was decreased to ~100 rpm. Mixing continued for 1 minute. The samples were allowed to settle and 20 ml aliquots were taken for turbidity rearlin~.c.
Once an optimum Polymer B/Polymer E dosage was dete....i..ed, a profile using Polymer A was performed. The procedure was the same as above, except that Polymer A was added to the sample first, and mixed for 1 minute at ~100 rpm. The proper dosage of Polymer E was then added, and the mixing speed was increased to ~200 rpm for 30 seconds. Polymer B was then added and the mixing speed was decreased to ~100 rpm. Mixing continued for 1 minute. The contents of the beaker were allowed to settle and 20 ml aliquots taken for turbidity reading~. The 20 ml aliquot was then returned to its original beaker and the contents of the beaker was slowly poured into a 1 liter graduated cylinder for DAF clarification ~im~ tion tests.
To simulate DAF air injection, 100 ml of pressurized (50 psi) deionized water was added to the water sample via a wand inserted to the bottom of grad~l~ted cylinder. This technique introduces micro-bubbles of dissolved air. As soon as 100 ml of pressurized deionized water was added to the cylinder, a timer was started to determlne the length of time it took for the solids (l.e. pulp fines, ash, stickies, etc.) to form a mat at the surface.
The water underneath the mat is called the DAF effluent for purposes of describing the invention. The DAF effluent was drained, via a valve at the bottom of the cylinder, from the cylinder. A 20 ml aliquot of the effluent was taken for a turbidity reading. Since the micro-bubbles from the simulated DAF process interfered with turbidlty readings, the 20 ml aliquot was placed in an ultrasonic water bath for 5 minutes to remove the micro-bubbles. The mat from the simulated DAF air iniection was filtered through a 40 ~m screen using gravity filtration.
Any particles remaining on the screen were then rinsed onto Whatman 41 filter paper and dried in drying rings overnight.
To obtain a total stickles count via image analysis, the effluent was drained from the cylinder and filtered through a 40 ~m screen. A clean Whatman 41 filter paper was placed on top of the particulate covered filter paper and pressed with a 300~F
iron for 2 minutes. The two filter papers were then carefully separated, and anything adhering to the top filter paper was counted as a stickie. Image analysis was utilized to quantify the stickies adhering to the top filter paper.
Image analysis is a method used to quantify both dirt and stickies in handsheets. Image analysis can detect either dark partlcles on a light background (dirt count) or light particles on a dark background (stickies analysis). A reverse dye method is used to quantify light partlcles on a dark back-ground. This method is outlined in an article by M. P. Hacker, TAPPIJ. 75 (7), 63, 1992. This method is performed by dyeing 9a CA 022l3367 l997-08-l9 the handsheets with a dark colored water-soluble dye. Stickies, being primarily hydrophobic in nature, will not accept this dye. This leaves a light colored area which can be measured through image analysis in the reverse polarity mode. Some stickies are naturally dark in color; stickies of this kind are in~ ded in the dirt count data.
With the image analysis stickies/dirt data, a percent stickies/dirt removal efficiency (%
SDRE) was calculated. Calculation of percent stickies/dirt removal is as follows:
%SDRE = Total count of untreated effluent - Total count of treated effluent Total count of untreated effluent 10 Where: Total count of untreated effluent = dirt count + stickies count for untreated effluent Total count of treated effluent = dirt count + stickies count for treated effluent Note: Stickies can pick up dark colored inks in the papel.llaking process and thus appear dark in color. For this reason, both dirt (dark particles on a light background) and stickies (light particles on a dark background) counts were in~ ded in the total counts for the treated and untreated effluents.
The Polymer B/Polymer E/Polymer A program worked very well in the lab on stickies removal. The Polymer B/Polymer E/Polymer A program had a 92.2% stickies/dirt removal efficiency and the Polymer B/Polymer E program had a stickies/dirt removal efficiency of 45.1%.
The clarity of the DAF effluent was much better with the Polymer B/Polymer E/Polymer A
program (23 NTU) than with the Polymer B/Polymer E program (72 NTU) and both treatment programs were better than the untreated DAF effluent (84 NTU).
ExamPle 3 A short trial was run at a Northeastern U.S. paper mill to enh~nce stickies removal in the DAF clarification system through the incorporation of Polymer A in the Polymer B/Polymer E
DAF polymer program. A stickies removal efficiency of up to 98.9% was achieved during the trial.
The trial was run to address a stickies/pitch/wax problem in the mill. The mill has two DAF clarifiers. One is an "effluent only" clarifier, where the accepts are sewered. The other is a "process" clarifier, where the accepts are recirculated back to the pap~""~rlline process water.
The mill was interested in a DAF chemical l,~l ",~.,l program that would decrease the amount of 10 stickies/pitch/wax that carried over to the paperm~rhine process water. Polymer treatm~ntc as described in Example 2 above were evaluated.
To determine the effectiveness of the trial, h~ntlcheetc were made for stickies analysis and colloidal pitch counts were performed on the DAF influent and çfflu~nt Colloidal pitch counts were performed using a microscope and a hemacytometer: 21.1 x 107 pitch particles/ml were obtained with 5 ppm Polymer E/8 ppm Polymer B, 4.4 x 107 pitch particles/ml were obtained with l S ppm Polymer E/20 ppm Polymer B, and 2. 8 x 107 pitch particles/ml were obtained with 15 ppm Polymer E/20 ppm Polymer B/90 ppm Polymer A. There was a significant decrease in the colloidal pitch counts with the addition of Polymer A to the treatm~nt For stickies analysis, 500 ml of sample was filtered through a 200 mesh (76~1m) Britt Jar screen. The sample was washed with three liters of water to be certain all of the fibers were washed through the screen. The particles on the screen were then washed onto Whatman 41 filter CA 022l3367 l997-08-l9 paper. The filter paper was removed and the side with the particles was joined with a clean filter paper. The two filter papers were pressed together using a 300~F iron for 2 minl~tçC~. The filter papers were then carefully separated, and any particles adhering to the top filter pad were counted as stickies.
Some of the particles adhering to the top filter paper were dark in color. These particles were counted with image analysis and were recorded as "dark" stickies. Other particles on the top filter paper were white in color or transparent. Since image analysis can only detect particles that have some contrast to the background, the top filter paper was dyed with a dark colored water soluble dye. Stickies, being primarily hydrophobic in nature, do not adsorb this dye. This 1O leaves a light colored particle area which can be measured with image analysis techniques. This measurement was recorded as "light" stickies.
With the image analysis data, a percent stickies removal efficiency (%SRE) was calculated. Calculation of percent stickies removal was as follows:
% SRE = Total count feed - Total count X 100 Total count offeed Where: Total count feed = Total stickies count of the feed Total count accepts = Total stickies count of the accepts The stickies removal efficiency (SRE) with 5 ppm Polymer E and 8 ppm Polymer B was 63 . 7%. Polymer B/Polymer E/Polymer A dosages were altered throughout the trial to determine the most efficient program. The most efficient program for stickies removal was with 15 ppm Polymer E/20 ppm Polymer B/90 ppm Polymer A. This program col"billalion yielded a 98.9%
stickies removal efficiency. With the 15 ppm Polymer E/20 ppm Polymer B program alone the SRE was 71.4%.
The use of Polymer A in co",bhlalion with the Polymer E coa~ nt/Polymer B flocculant program proved to be highly effective in increasing the stickies removal efficiency in the DAF
clarification system.
Example 4 A 30 day trial was run at the same Northeastem U.S. paper mill to çnh~nce stickies removal in the DAF clarification system through the incorporation of Polymer A in the existing Polymer E/Polymer B DAF polymer program. Using the analysis techniques described in 1C Example 3, a stickies removal efficiency of up to 98.9% was achieved during the trial.
The stickies removal efficiency (SRE) with 10 ppm Polymer E and 8 ppm Polymer B was 33.3%. Polymer E/Polymer B/Polymer A dosages were altered throughout the trial to determine the most efficient program. The most efficient program for stickies removal was with 18 ppm Polymer E/13 ppm Polymer B/80 ppm Polymer A. This program co",bil,alion yielded a 98.9%
stickies removal efficiency. With a 15 ppm Polymer E/13 ppm Polymer B program alone, the SRE was 88.4%.
The use of Polymer A in combination with the Polymer E coa~ nt/Polymer B flocculant program proved to be highly effective in increasing the stickies removal efficiency in the DAF
clarification system.
Changes can be made in the composition, operation and arrangement of the method and the polymers of the present invention described herein without dep~ l;llg from the concept and scope ofthe invention as defined in the following claims:
Claims (6)
1. A method for removing secondary fiber contaminants from paper mill process waters comprising:
adding a polyvinyl chloride, a cationic polymeric coagulant and a polymeric flocculant to paper mill process waters containing secondary fiber contaminants in an amount sufficient to agglomerate the secondary fiber contaminants to larger particle sizes; and removing the secondary fiber contaminants from the process waters by a dissolved air flotation clarification process.
adding a polyvinyl chloride, a cationic polymeric coagulant and a polymeric flocculant to paper mill process waters containing secondary fiber contaminants in an amount sufficient to agglomerate the secondary fiber contaminants to larger particle sizes; and removing the secondary fiber contaminants from the process waters by a dissolved air flotation clarification process.
2. The method according to Claim 1 wherein agglomeration is conducted at a temperature in the range between about 70° F. to about 160° F.
3. The method according to Claim 2 wherein agglomeration is conducted at a temperature in the range between about 100° F. to about 140° F.
4. The method according to Claim 1 wherein the polyvinyl chloride is added to the paper mill process waters in an amount between about 10 parts per million to about 100 parts per million, based on the volume of the paper mill process water.
5. The method according to Claim 1 wherein the cationic polymeric coagulant is added to the paper mill process waters in an amount between about 1 to about 50 parts per million based on the volume of the paper mill process water.
6. The method of Claim 1, wherein the polymeric flocculant is added to the paper mill process waters in an amount between about 1 to about 25 parts per million based on the volume of the paper mill process water.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/700,000 | 1996-08-20 | ||
| US08/700,000 US5798046A (en) | 1996-08-20 | 1996-08-20 | Enhanced removal of hydrophobic contaminants from water clarification systems |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2213367A1 true CA2213367A1 (en) | 1998-02-20 |
Family
ID=24811810
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2213367 Abandoned CA2213367A1 (en) | 1996-08-20 | 1997-08-19 | Enhanced removal of hydrophobic contaminants from water clarification systems |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US5798046A (en) |
| EP (1) | EP0825293B1 (en) |
| AU (1) | AU719019B2 (en) |
| BR (1) | BR9704472A (en) |
| CA (1) | CA2213367A1 (en) |
| DE (1) | DE69701074T2 (en) |
| ES (1) | ES2140938T3 (en) |
| ID (1) | ID18056A (en) |
| MY (1) | MY115550A (en) |
| NO (1) | NO973815L (en) |
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| JP2952373B1 (en) | 1998-09-09 | 1999-09-27 | 株式会社 羽野組 | How to clean buildings |
| US6890431B1 (en) * | 2000-02-18 | 2005-05-10 | The F. B. Leopold Co., Inc. | Buoyant media flotation |
| US6666950B2 (en) | 2001-11-28 | 2003-12-23 | Basf Ag | Process for deinking paper using a triglyceride |
| US7168387B1 (en) | 2006-01-26 | 2007-01-30 | King Fahd University Of Petroleum And Minerals | Submersible craft for water purification |
| MX2009011956A (en) * | 2007-05-16 | 2009-11-13 | Buckman Labor Inc | Methods to detect organic contaminants in pulp and fiber. |
| US8160305B2 (en) * | 2007-11-30 | 2012-04-17 | Hercules Incorporated | Method and apparatus for measuring deposition of particulate contaminants in pulp and paper slurries |
| US8353641B2 (en) * | 2008-02-14 | 2013-01-15 | Soane Energy, Llc | Systems and methods for removing finely dispersed particulate matter from a fluid stream |
| US8349188B2 (en) * | 2008-02-14 | 2013-01-08 | Soane Mining, Llc | Systems and methods for removing finely dispersed particulate matter from a fluid stream |
| US8945394B2 (en) * | 2009-10-27 | 2015-02-03 | Soane Energy, Llc | System, methods, processes and apparatus for removing finely dispersed particulate matter from a fluid stream |
| MX340615B (en) | 2009-02-27 | 2016-07-18 | Soane Mining Llc | Systems, methods, processes and apparatus for removing finely dispersed particulate matter from a fluid stream. |
| US8980059B2 (en) | 2009-08-12 | 2015-03-17 | Nanopaper, Llc | High strength paper |
| US8821733B2 (en) | 2009-09-29 | 2014-09-02 | Soane Mining, Llc | Systems and methods for recovering fine particles from fluid suspensions for combustion |
| WO2013188630A2 (en) | 2012-06-15 | 2013-12-19 | Nanopaper, Llc | Additives for papermaking |
| WO2013191752A1 (en) | 2012-06-18 | 2013-12-27 | Soane Mining, Llc | Systems and methods for removing finely dispersed particles from mining wastewater |
| US10782241B2 (en) | 2017-07-27 | 2020-09-22 | Ecolab Usa Inc. | Method of determining residual flocculant in effluent of an industrial clarification process |
Family Cites Families (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1179098B (en) * | 1961-05-03 | 1964-10-01 | Basf Ag | Flotation agent for clarifying waste water containing paper fibers |
| US3764460A (en) * | 1969-04-01 | 1973-10-09 | Japan Maize Products Co Ltd | Process of deinking waste paper materials |
| US3873418A (en) * | 1970-02-09 | 1975-03-25 | Savo Oy | Method of recovering noil fibres and soluble wood material from waste water |
| CA1024274A (en) * | 1973-11-28 | 1978-01-10 | Pulp And Paper Research Institute Of Canada | Treatment of pulp mill effluents |
| US4076578A (en) * | 1974-10-21 | 1978-02-28 | Canadian Patents And Development Limited | Ink removal from waste paper |
| US4276118A (en) * | 1979-10-09 | 1981-06-30 | Weyerhaeuser Company | Deinking waste electrophotography copy paper |
| US4886575A (en) * | 1985-10-08 | 1989-12-12 | Betz Laboratories, Inc. | Detackification of adhesive materials contained in secondary fiber with polyvinyl alcohol |
| US4738750A (en) * | 1986-02-10 | 1988-04-19 | Stone Container Corp. | System and method for treating pulp and paper mill waste water |
| JPS63152493A (en) * | 1986-12-11 | 1988-06-24 | 新王子製紙株式会社 | Removal of pitch in water of pulp paper producing process |
| CA1316300C (en) * | 1988-07-19 | 1993-04-20 | Richard N. Van Oss | Method for pacifying stickies in paper |
| EP0473653B1 (en) * | 1989-05-22 | 1995-11-08 | Commonwealth Scientific And Industrial Research Organisation | Effluent treatment |
| US5080759A (en) * | 1990-09-04 | 1992-01-14 | Quaker Chemical Corporation | Method for controlling stickies in pulp and papermaking processes using recycled paper |
| GB2251868B (en) * | 1990-12-24 | 1994-07-27 | Grace W R & Co | Pitch control |
| US5230808A (en) * | 1991-06-17 | 1993-07-27 | Nalco Canada Inc. | Liquid suspension of polyethylene oxide for use in treating paper and pulp wastewater |
| US5173208A (en) * | 1991-06-17 | 1992-12-22 | Nalco Canada Inc. | Liquid suspension of polyethylene oxide for use in treating paper and pulp wastewater |
| US5256254A (en) * | 1991-07-12 | 1993-10-26 | Betz Paperchem, Inc. | Methods of controlling deposition in a paper machine dryer section |
| US5266166A (en) * | 1992-05-18 | 1993-11-30 | Betz Paperchem, Inc. | Methods for controlling the deposition of organic contaminants in pulp and papermaking processes using a polyalkylene oxide/vinyl acetate graft copolymer |
| US5246547A (en) * | 1992-07-14 | 1993-09-21 | Nalco Chemical Company | Hydrophobic polyelectrolyte coagulants for the control of pitch in pulp and paper systems |
| US5405495A (en) * | 1993-07-02 | 1995-04-11 | Nalco Chemical Company | Recycling of xerographic waste paper using organic particulates |
-
1996
- 1996-08-20 US US08/700,000 patent/US5798046A/en not_active Expired - Fee Related
-
1997
- 1997-08-19 CA CA 2213367 patent/CA2213367A1/en not_active Abandoned
- 1997-08-19 EP EP19970114313 patent/EP0825293B1/en not_active Expired - Lifetime
- 1997-08-19 ID ID972898A patent/ID18056A/en unknown
- 1997-08-19 NO NO973815A patent/NO973815L/en not_active Application Discontinuation
- 1997-08-19 ES ES97114313T patent/ES2140938T3/en not_active Expired - Lifetime
- 1997-08-19 DE DE1997601074 patent/DE69701074T2/en not_active Expired - Fee Related
- 1997-08-20 AU AU35177/97A patent/AU719019B2/en not_active Ceased
- 1997-08-20 MY MYPI9703820 patent/MY115550A/en unknown
- 1997-08-20 BR BR9704472A patent/BR9704472A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| ID18056A (en) | 1998-02-26 |
| EP0825293B1 (en) | 2000-01-05 |
| DE69701074D1 (en) | 2000-02-10 |
| NO973815L (en) | 1998-02-23 |
| EP0825293A1 (en) | 1998-02-25 |
| NO973815D0 (en) | 1997-08-19 |
| BR9704472A (en) | 1999-03-09 |
| AU719019B2 (en) | 2000-05-04 |
| AU3517797A (en) | 1998-02-26 |
| DE69701074T2 (en) | 2000-10-12 |
| US5798046A (en) | 1998-08-25 |
| MX9706328A (en) | 1998-07-31 |
| ES2140938T3 (en) | 2000-03-01 |
| MY115550A (en) | 2003-07-31 |
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