WO1991010500A1 - Method for recovering coating slip waste - Google Patents

Method for recovering coating slip waste Download PDF

Info

Publication number
WO1991010500A1
WO1991010500A1 PCT/FI1990/000023 FI9000023W WO9110500A1 WO 1991010500 A1 WO1991010500 A1 WO 1991010500A1 FI 9000023 W FI9000023 W FI 9000023W WO 9110500 A1 WO9110500 A1 WO 9110500A1
Authority
WO
WIPO (PCT)
Prior art keywords
coating slip
waste
coating
slip
recovered
Prior art date
Application number
PCT/FI1990/000023
Other languages
French (fr)
Inventor
Juha Varpula
Original Assignee
Yit-Yhtymä Oy
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Yit-Yhtymä Oy filed Critical Yit-Yhtymä Oy
Priority to PCT/FI1990/000023 priority Critical patent/WO1991010500A1/en
Publication of WO1991010500A1 publication Critical patent/WO1991010500A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14—Ultrafiltration; Microfiltration
    • B01D61/145—Ultrafiltration
    • 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
    • D21H19/00—Coated paper; Coating material

Definitions

  • the invention relates to a method for recover ⁇ ing coating slip waste of especially paper or board. So far the waste water which contains coating pigment and is released from a paper machine has been purified by chemical processes in paper mills. The dry matter of coating slip, or pigment, has been re ⁇ covered by precipitation, and the obtained precip- itate has been formed to paper filler. Filter aids, vacuum filtration, centrifugation and other separa ⁇ tion processes have been used for the drying of the precipitate. Thereby the precipitated slip does not correspond to the original one. At present, the coat- ing slip waste treated in the manner described above is mainly taken to a dump.
  • Finnish Patent Application No. 86,004 discloses a method which is based on the separation of a glu ⁇ tinous coating slip fraction by precipitation to sur- face filler for paper.
  • Finnish Patent Application No. 811,910 discloses a solution which is likewise based on the generally known pre ⁇ cipitation wherein a stable dispersion is broken with precipitating chemicals. The composition of the dry matter in the coating slip waste treated in this manner changes when precipitants are added thereto, and it no longer corresponds to the original coating slip.
  • the object of the present invention is to provide a new method for recovering coating slip waste, by means of which the dry matter of the re ⁇ covered coating slip waste is of better quality than what has been obtained by the previous methods.
  • the method according to the invention is mainly characterized in that the coating slip waste is de- hydrated without chemicals, and the recovered coating slip is reintroduced to coating.
  • Figures 1 to 4 show a comparison between the flow patterns of conventional filtration and the ultrafiltration used in the method according to the invention.
  • Figures 5 and 6 show a separation process occurring on a membrane surface.
  • Figure 7 shows a basic diagram of the method according to the invention.
  • the dry matter of the coating slip is recovered in the form of the original stable dispersion.
  • the feed solution in ultrafiltration flows in the direc ⁇ tion of the membrane surface, and the membrane is not clogged since the separating particles do not penet ⁇ rate the membrane pores ( Figure 3) as in microfiltra- tion.
  • the separation process in a micro scale
  • the circles repre ⁇ sent the separating material particles.
  • the particles drift to the membrane surface at the rate J (the value of the flux).
  • the par ⁇ ticles accumulate in a laminar layer and form a gel layer, which prevents the moving of material.
  • the concentration of the gel layer is C-, and the thick ⁇ ness of the gel layer is dn. It is further known that the concentration of the gel layer is higher than the concentration C ⁇ of the feed flow, the separating particles diffusing through the boundary layer back to the lower concentration.
  • the thickness X n of the boundary layer and the resistance to the moving of material depend on the flow rate (Q) in the direction of the membrane surface and, above all, on the re ⁇ pulsion forces of the particles to be separated and the stability of the dispersion.
  • the coating slip waste is recovered preferably by ultrafiltration, whereby no chemicals are needed since the gel layer which is formed on the membrane surface is stable.
  • the recovered coating slip is merely dehydrated, and thus the coating slip can be reused.
  • the concentration of the recovered concentrate can be adjusted by the ultrafiltration process as desired.
  • the recovered coating slip concentrate can be used as one component of fresh coating slip.

Landscapes

  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

The invention relates to a method for recovering the coating slip waste of especially paper or board. Waste water containing coating slip is formed e.g. in paper mills. According to the invention, the coating slip waste is dehydrated without chemicals, and the recovered coating slip is reintroduced to the coating process.

Description

Method for recovering coating slip waste
The invention relates to a method for recover¬ ing coating slip waste of especially paper or board. So far the waste water which contains coating pigment and is released from a paper machine has been purified by chemical processes in paper mills. The dry matter of coating slip, or pigment, has been re¬ covered by precipitation, and the obtained precip- itate has been formed to paper filler. Filter aids, vacuum filtration, centrifugation and other separa¬ tion processes have been used for the drying of the precipitate. Thereby the precipitated slip does not correspond to the original one. At present, the coat- ing slip waste treated in the manner described above is mainly taken to a dump.
Finnish Patent Application No. 86,004 discloses a method which is based on the separation of a glu¬ tinous coating slip fraction by precipitation to sur- face filler for paper. On the other hand, Finnish Patent Application No. 811,910 discloses a solution which is likewise based on the generally known pre¬ cipitation wherein a stable dispersion is broken with precipitating chemicals. The composition of the dry matter in the coating slip waste treated in this manner changes when precipitants are added thereto, and it no longer corresponds to the original coating slip.
The object of the present invention is to provide a new method for recovering coating slip waste, by means of which the dry matter of the re¬ covered coating slip waste is of better quality than what has been obtained by the previous methods.
The method according to the invention is mainly characterized in that the coating slip waste is de- hydrated without chemicals, and the recovered coating slip is reintroduced to coating.
In the following, the invention will be described with reference to the attached drawing. Figures 1 to 4 show a comparison between the flow patterns of conventional filtration and the ultrafiltration used in the method according to the invention.
Figures 5 and 6 show a separation process occurring on a membrane surface.
Figure 7 shows a basic diagram of the method according to the invention.
According to the present invention, the dry matter of the coating slip is recovered in the form of the original stable dispersion. As is known, the feed solution in ultrafiltration flows in the direc¬ tion of the membrane surface, and the membrane is not clogged since the separating particles do not penet¬ rate the membrane pores (Figure 3) as in microfiltra- tion. On the other hand, the separation process (in a micro scale) occurring on the membrane surface and shown in Figures 5 and 6 is known. The circles repre¬ sent the separating material particles. The particles drift to the membrane surface at the rate J (the value of the flux). On the membrane surface the par¬ ticles accumulate in a laminar layer and form a gel layer, which prevents the moving of material. The concentration of the gel layer is C-, and the thick¬ ness of the gel layer is dn. It is further known that the concentration of the gel layer is higher than the concentration C^ of the feed flow, the separating particles diffusing through the boundary layer back to the lower concentration. The thickness Xn of the boundary layer and the resistance to the moving of material depend on the flow rate (Q) in the direction of the membrane surface and, above all, on the re¬ pulsion forces of the particles to be separated and the stability of the dispersion.
According to the invention, the coating slip waste is recovered preferably by ultrafiltration, whereby no chemicals are needed since the gel layer which is formed on the membrane surface is stable. The recovered coating slip is merely dehydrated, and thus the coating slip can be reused. Simultaneously, the concentration of the recovered concentrate can be adjusted by the ultrafiltration process as desired. The recovered coating slip concentrate can be used as one component of fresh coating slip.

Claims

Claims :
1. A method for recovering the coating slip waste of especially paper or board, c h a r a c - t e r i z e d in that the coating slip waste is dehydrated without chemicals, and the recovered coat¬ ing slip is reintroduced to coating.
2. A method according to claim 1, c h a r ¬ a c t e r i z e d in that the coating slip waste is dehydrated by ultrafiltration.
3. A method according to claim 1 or 2, c h a r a c t e r i z e d in that the concentration of the recovered coating slip is adjusted by an ultrafiltration process.
4. A method according to claim 1, c h a r ¬ a c t e r i z e d in that the recovered coating slip concentrate is reused as one component of fresh coat¬ ing slip.
PCT/FI1990/000023 1990-01-19 1990-01-19 Method for recovering coating slip waste WO1991010500A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/FI1990/000023 WO1991010500A1 (en) 1990-01-19 1990-01-19 Method for recovering coating slip waste

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/FI1990/000023 WO1991010500A1 (en) 1990-01-19 1990-01-19 Method for recovering coating slip waste

Publications (1)

Publication Number Publication Date
WO1991010500A1 true WO1991010500A1 (en) 1991-07-25

Family

ID=8556486

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1990/000023 WO1991010500A1 (en) 1990-01-19 1990-01-19 Method for recovering coating slip waste

Country Status (1)

Country Link
WO (1) WO1991010500A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0894770A1 (en) * 1997-07-30 1999-02-03 Procoat Technologies Process and device for treating opaque pollutants in industrial and/or agricultural wastewater
WO2000001886A1 (en) * 1998-07-02 2000-01-13 Upm-Kymmene Corporation A method for making coating colour
EP1052327A1 (en) * 1999-05-14 2000-11-15 Voith Sulzer Papiertechnik Patent GmbH White water circuit and process for the circulation of water in a papermachine

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2649758A (en) * 1950-12-05 1953-08-25 Us Rubber Co Coating machine with circulating system
US4661385A (en) * 1985-06-04 1987-04-28 Amchem Products, Inc. Filtration stabilization of autodeposition baths

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2649758A (en) * 1950-12-05 1953-08-25 Us Rubber Co Coating machine with circulating system
US4661385A (en) * 1985-06-04 1987-04-28 Amchem Products, Inc. Filtration stabilization of autodeposition baths

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JOURNAL WPCF, Vol. 53, No. 7, 1981, ERIK R. CHRISTENSEN, KURT W. PLAUMANN, "Waste Reuse: Ultrafiltration of Industrial and Municipal Wastewaters", page 1212. *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0894770A1 (en) * 1997-07-30 1999-02-03 Procoat Technologies Process and device for treating opaque pollutants in industrial and/or agricultural wastewater
FR2766811A1 (en) * 1997-07-30 1999-02-05 Procoat Technologies METHOD AND DEVICE FOR THE TREATMENT OF WASHING WATER FROM SLEEPING SAUCES
WO2000001886A1 (en) * 1998-07-02 2000-01-13 Upm-Kymmene Corporation A method for making coating colour
EP1052327A1 (en) * 1999-05-14 2000-11-15 Voith Sulzer Papiertechnik Patent GmbH White water circuit and process for the circulation of water in a papermachine
US6497788B1 (en) 1999-05-14 2002-12-24 Voith Sulzer Papiertechnik Patent Gmbh Backwater cycle and process for the water circulation of a paper machine

Similar Documents

Publication Publication Date Title
ES8403325A1 (en) Polyamide membrane with controlled surface properties and process for its production.
WO1991010500A1 (en) Method for recovering coating slip waste
ES8403326A1 (en) Polyamide membrane and process for its production.
Chang et al. Experimental investigation of the effect of particle size distribution of suspended particles on microfiltration
US5164080A (en) Ion-exchange treatment apparatus for dispersions
CA2175602A1 (en) Filtering method and apparatus
US5385239A (en) Low brightness functional pigment from process by-product
CA1059926A (en) Purification of papermarking waste water using pulp stock rejects as filter aid
US4869829A (en) Process for separating solids with a keratin filter aid
SE431570B (en) PROCEDURE FOR RECOVERY OF CELLULOSA FIBERS FROM RECOVERY PAPERS
FI83444C (en) Procedure for the collection of coating paste waste
US4028255A (en) Preparation of polymer composites
Aimar et al. Fouling and concentration polarisation in ultrafiltration and microfiltration
JP4112401B2 (en) Recovery method of sulfur from leaching residue by atmospheric pressure method
US4468317A (en) Selective rheological separation of clays
WO2001044115A3 (en) Waste water treatment system
US4301001A (en) Process for concentrating mica in a mixture of sand and mica
CA2034367A1 (en) Method of recovering coating colour waste
ATE120977T1 (en) DEVICE FOR THE SEPARATION OF PARTICLES CONTAINING SOLIDS FROM AQUEOUS SUSPENSIONS.
EP0388628A3 (en) Process for the separation of particles from fermentable or fermented suspensions of beverage production
GB2154224A (en) Clay dewatering process
JP3078017B2 (en) Method and equipment for recovering raw materials from residue or collected material streams generated during paper production
US4406781A (en) Process for the separation of mineral substances
JP2814417B2 (en) Method and apparatus for sedimentation and separation of suspension
Tanaka et al. Relationship between cake structure and membrane pore size in crossflow filtration of microbial cell suspension containing fine particles

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): DE FI NO SE SU

WR Later publication of a revised version of an international search report
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642