US2005742A - Process for deinking imprinted paper - Google Patents

Process for deinking imprinted paper Download PDF

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Publication number
US2005742A
US2005742A US72757734A US2005742A US 2005742 A US2005742 A US 2005742A US 72757734 A US72757734 A US 72757734A US 2005742 A US2005742 A US 2005742A
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United States
Prior art keywords
stock
paper
froth
flotation
ink
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English (en)
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Pierre R Hines
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Priority to US72757734 priority Critical patent/US2005742A/en
Priority to GB1707934A priority patent/GB441331A/en
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Priority to FR793990D priority patent/FR793990A/fr
Publication of US2005742A publication Critical patent/US2005742A/en
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    • 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
    • D21C5/025—De-inking
    • 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

Definitions

  • the object of my invention is rto provide an efficient and practical process for removing carl"non inks from imprinted paper.
  • Waste imprinted paper may readily be reconverted into stock, but beforesuch stock may again be usedv for making paper, the imprinted ink must ⁇ be removed. In other words, the paper must be inking of the-paper.
  • My invention hasfor its purpose to provide a process adaptable for de-inking papers Aof all classes-newspapers, sgmagazines, ledgers and bookswith a negligibleloss ofv thepaperstOck and filler, and without deleterious effectupon the fiber composing the de-inked stock.
  • the carbon particles of the ink with which paper has been imprinted may be loosened from the paper fibers of imprinted paper and I'have discovered that when the carbon particles have been freed from the fiber, they may then beremovedl by flotation in the form of a froth,'so'as to leave the fibers cleaned of the inkas a residuum.
  • flotation I refers to a process similar'toA that employed for separating .minera1; Vbut before flotation can be accomplished the stock rmust-be suitably prepared which preparation .constitutes one of the essential steps of my invention.
  • refining I mean the separation of the fibers from each other, (defiberizing) andproducing stock suitable forv making paperon a papermachine.
  • the paper is first dusted, and ⁇ preferably shredded.
  • Shredding facilitates the reconvertirg of the paper into stock.
  • the shredding operation may be convenientlyl performedy ina hammer mill, or paper shredder available.
  • vthe ink has been freed; y y ⁇ brought to a proper ⁇ consistency, foriiotation.
  • the .flotation operation yisimpedeci by too, thiclc; lstock and too thin a stock,requires too.V much
  • the shredded paper may y Y l y and ,refined by either one of two vWell-lrnovvn methods; ⁇ namely/,by the lcirculating Icookingtank method,.or the rotary-cooker rnethod,but
  • vThe stock may be cooked vvitlrsorne.allnrli,y not lexceeding the equivalent vofs-4% y ofy ;caustic ..soda,
  • the newspapers are sorted, 4dusted and weighed, then preferably are shredded with yone o! thev usual shreddersfin common use, and then.; is refined by thoroughly .beating in a .”broke' beater or beatercommonly-,used in papermiils, or may be agitated in a tanky by, afpump,v rnechanical impeilers, or .similarmeans ',Inzthede-inkingof newspapers, it ,is prefer-VVA v)able that the temperature of the beater-.water ⁇ be-lcept at from 140to 1,60y degrees z-F. News-- paper. defiberizes more ⁇ easilyinqfyater., of lthat temperature.
  • Consistency for. flotation The defiberizedandrefined stoclrz. from which fromV lthe-fiber must be ⁇ flotation cell capacity.
  • a ,consistency of 1 -11A,%, v(8() lao-100 parts of water to one of original paper by dry weight) is'desirable. Due to variations in sizing, certain .waste .pa-
  • the carbon ink particles may be flocculated, if the pH value is above 7.0, by adding burnt lime (calcium oxide), magnesium oxide or similar reagent.
  • burnt lime calcium oxide
  • magnesium oxide magnesium oxide
  • the lime and similar salts precipitate the sodium soaps which causes the ink particles to flocculate.
  • Approximately pounds of burnt lime per ton of original or dry weight of paper is sufllcient for average No. l books and old magazines.
  • the dispersion of the mineral fillers in the paper retards their tendency to float oil' in the froth.
  • sodium silicate or starch suitable dispersing agents when Ythe pH value of the stock is above 7.0.
  • Sodium silicate may be added at the rate of 10 lb. or less per ton of original dry weight of paper. If soluble starch is used, it may be used in amounts not exceeding 8 1b. per ton of dry paper.
  • Either lime or sodium silicate may be substituted for an equivalent amount of other alkali to assist in the cooking and refining operation.
  • the addition of 4-10 lb. per ton of dry paper, of an acid, such as sulphuric, or one of the alum salts may be used to flocculate the ink and disperse the filler.
  • the soaps formed in refining and cooking with an alkali of sized papers also contribute to froth formation, since a small amount of size, from a paper-makers standpoint, Vi'orrns a relatively ⁇ large amount of frothing agent, from a flotation Rosins and similar soaps have two extremes;
  • a reagent such as sulphurlc acid
  • the removalV of cooking liquor may be accomplished by filtering or similar means immediately following the cooking and refining step.
  • the volume of froth may also be reduced by the addition of 4-8 lb. of kerosene or similar reagent per ton of dry Weight of paper treated, and this is probably the most practical method. It is usually desirable to modify the type of froth bythe addition of one to two pounds per ton of dry paper, of a light frothing reagent, such as cresylic acid, pine oil, or one of thehigh boiling point synthetic alcohols, known commercially as Du Pont Frothers.
  • Newsprint contains little or no size, and rarely fillers.
  • the carbon inks are incorporated with mineral and fish oils and are dried by absorption.
  • Newsprint is made with a. large proportion of ground wood pulp which containstannic acid. Tannic acid is toxic and prohibits froth formation.
  • a suitable froth may be obtained by raising the pH value of the stock to 8.5-9.0 in combination with frothing reagents.
  • the lighter frothing reagents may be used in amounts of approximately four pounds per ton of dry weight of paper.
  • the heavier frothing reagents such as Barrets No.
  • coal taroil pine tar oil, hardwood creosotes may also be used, and it will be found advantageous to add these during the cooking and refining stage, thus to thoroughly incorporate them in the stock.
  • the Du Pont 'Frothers are particularly good for newsprint.
  • the paper stock to be de-inked has a pH value of below 7.0, flotation reagents both light and heavy, and in combination, mayV be Yused atthe rate of 8 lb. and upwardsper ton of Vdry paper.
  • the froth bubbles should be polygonal in shape with enough toughness to carry over well, Vand breaking down to liquid readily.
  • the volume of froth should be less than 20%- of the total Volume of stock being floated, anda smaller volume is better. augmented as above mentioned for producing eilicient separation and removal of -the ,ink par,
  • the high boiling point synthetic alcohols (commercially known as Du Pont Frothers) mentioned above under frothing reagents, also have excellent collecting properties for carbon ink particles.
  • Kerosene or similar products have excellent collecting properties, as well as being useful in modifying excessive froths, and it works well 4in connection with the Du Pont Frothers.
  • sodium cleate if used in'small amounts is an excellent collector of ink, but if used Vin large amounts disperses the carbon ink particles. If newsprint is to be de-inked sodium oleate may be added to the cooking step in the amount of two pounds or less per ton of dry paper. It has good detergent properties, as well.
  • Equal parts of amyl acetate and butyl alcohol have good collecting properties for carbon ink particles, and are excellent modifiers of heavy' and voluminous froths; Two pounds or less of each per ton of dry paper should be used.
  • the stock should be agitated for two to threeminutes prior to flotation. This is termed conditioning in flotation work, and the stock from the storage chest may be pumped continuously to an agitating chest or tank of sufficient size to give proper conditioning time. If the stock requires the addition of water to dilute it to a proper consistency for flotation, the stock and water may be delivered continuously at constant rate to the conditioning tank, and the reagents added continuously at a constant rate at the same time by means of flotation reagent feeders.
  • the first froth produced will be found heavier in ink than the froth from thevsucceeding compartments of the flotation machine.
  • the froth produced in the machine raises freed ink clots, and inky fibers from the stock, also some clean fiber and filler are entrained in the froth.
  • the stock passes thru the remaining compart-r ments of the flotation machine, and finally is discharged as a de-inkedstock but with most of the mineral filler still in it.
  • the froth from the third and successive compartments of the flotation machine is returned to the nrst compartment and flows through the second compartment to the third, where it JoinsY and Wasted. It also saves clean fiber and Iflller which have become entrained in the froth by returning the latter to the circuit. In this way the fiber and filler loss is confined substantially to very dirty fibers andl filler material which have ink clots adhering to them, which Ifound to be about 2% to 5% of the original dry weight of paper.
  • my flotation method may consist of 'two steps.
  • the first step called roughing uses a dense, heavy collecting froth; the last compartments, in this'case, acting as safety traps catching the occasional inky fiber and carbon particles which may have escaped; at the same time some clean fiber.
  • the second step is theretreatment of the first froth termed cleaning.
  • the second froth is rich in inky fibers and carbon' particles, and low in entrained clean fiber and filler, as a lesser numberk of ber and particles are the wrong direction to stay in the closed circuit until they are finally rejected.
  • thefroth from the rougher cell is sent to a smaller cleaner cell, and the froth from the latter is rejected, and the stock the cleaner" cell is returned to the feed of the first or rougher" cell.
  • the selection of the proper size of flotation machine should be made so as to give a frothing time in the first treatment of at least six to eight minutes.
  • the specific gravity of the stock may, for practical purposes, be taken as 1. lPaper stock stays in suspension for long periods compared to ore pulps and the vigorous actionv required in the mineral industry to keep the vheavy minerals in suspension isrnot required in deinking paper.
  • the first froth generally breaks down readily into a stock ofv approximately the same consistency as the original stock treated by flotation.
  • the de-inked stock may then be filtered upon one of the well-known types of filters to remove flotation reagentsand lightlyY washed, prior to bleaching or subsequent operations commonly employed for converting .the stock into paper.
  • the filtrate may be used for diluting the cooked F ⁇ Spray water may be used to assist in breaking and refined stock coming to the chest prior to flotation, thus saving water in bringing the stock to the required density.
  • This filtrate carries'the soluble reagents left in the stock and the amount 'of new reagents required is only that necessary to bring up the lstoel: to the original amounts specified. This also saves very nne filler in the filtrate or white water which may have escaped the filtering or de-watering operation.
  • the rejected froth and inky bers may be washed and used for board or other stock where whiteness is of no importance.
  • a laboratory flotation machine furnishes results which are dependable for controlling full scale results and may be used to determine in advance the best practice for operating under local or specialc'onditions.
  • a 6% consistency stock is furnished to the cooker togetherv with 4% of caustic soda and 1% of burnt lime (calcium oxide). yThe temperature is brought up with steam to i90-210 degrees F. and the stock rapidly circulated for 3-4 hr. determined by test or sample to see the stock is thoroughly defiberized.
  • the cook is then discharged toga storage chest from which it is pumped at a constant rate by a stock pump to a conditioning chest.
  • Water or filtrate from the finished stock is added at a constant rate to maintain the consistency in the conditioner at 11/4
  • Reagents are then added at a constant rate by means of reagent feeders in the. following amounts *perA ton of dry paper: eight pounds of kerosene, one pound of B24 Du Pont Frother and two pounds of soluble starch.
  • the conditioning tank should be. of such size as to give three minutes conditioning time prior to notation.
  • the conditioned stock is preferably pumped by a stock pump so that a constant rate of 'feed to the flotation maybe maintained.
  • the first or rougher froth is sent by means of a launder to a cleaner cell of the pneumatic type, and the froth is well sprayed with wash water to .break down the froth.
  • the cleaned stockv from the rougher cell is sent to a filter, and the filtered stock is then sent for a lightbleach' to the bleachery,
  • 'I'he stock from the cleaner cell may be sum- ⁇ ciently bright to be mixed with the clean stock from the rougher cell. If not, it is returned to the first or rougher cell for re-treatment.
  • the nitrate or white water from the filter il delivered to a storage tank. and may be used to dilute cooked stock in the conditioning tank.
  • the sorted newspapers are-then shredded pref-f erabjly in a wet type hammer mill, using water to carry the paper through the hammer mill,
  • the newspapers are cooked at a consistensy of about 3% with 25 lb. of caustic soda, and four pounds of sodium silicate per ton of dry newspaper.
  • the temperature is maintained at 140 deg. F. andthe cook rapidly circulated for one hour.
  • the deberized stock is discharged to a storage chest, and from there pumped at constant ratelto a conditioning tank. 'I'he stock is diluted to a consistency of l 1/.,% in the conditioning tank. Sufficient caustic soda is added to give a pH rvalue of 9.0. to the 11A% consistency stock.
  • the conditioner tan-lt is of such size as to give three minutes-agitation prior to entering the flotation circuit.
  • the conditionedstock is then fed to a pneu. matic cell of suflcient size to giveG-minutes otation time, the rst or rougher froth going to ay cleaner cell, thev second or cleaner cell froth going direct to sewer or Waste.
  • the stock from the cleaner cell is returned to the head of the rougher cell for re-treatment.
  • the clean stock from the rougher cell is sent to a paper-mill decker and de-Wateied.
  • the dewatered clean stock is then sentv to storage chests. If any of the newspapers are brown from ageing, zinc hydrous sulphlte may be used to brighten the stock, otherwise it is ready for paper.
  • de-inking paper which comprises rening and cooking the stock, with a chemical adapted-to .free substantially the ink particles from the pulp-fiber, until tests show the stock to be defiberized andthe fiber substantially freed from ink particles, bringing the stock to a suitable consistency, effecting occulation of the ink particles, and dispersion of other constituents by an agency selected relatively to the pH value of theY stock, effecting frothing and collecting by a. suitable agent, and removing the ink particles by froth flotation method.
  • de-inking paper which comprises refining and cooking the stock, with a chemical adapted to free substantially the ink particles from the pulp fiber, until tests show ⁇ the stock to be dcfiberized and the fiber substantially freed from ink particles, bringing the stock to a suitable consistency, effecting flocculation of the ink particles, and disp-ersion of other constituents by an agency selected relatively to the pH value of the stock, effecting frothing and collecting by a suitable agent, and removing the ink4 particles by froth flotation method including roughing and cleaning stages.
  • de-inking paper which comprises refining and cooking the stock, with a chemical adapted to free substantially the ink particles from the pulp fiber, until tests show the stock to be defibcrized and the fiber substantially freed from ink particles, bringing the stock to a suitable consistency, effecting flocculation of the ink particles, and dispersion of other constituents by an agency selected relatively to the pH value of the stock, effecting frothing and collecting by a suitable agent, removing the ink particles by iiotation operation, and removing fiotaticn reagents from cleaned stock.
  • the process of de-inking imprinted paper which comprises macerating the imprinted stock, adding, While agitating the stock, agents having alkaline, dispersing and collecting properties, cooking the paper stock until tests taken from the stock show the fiber to be substantially freed from ink particles, agitating the paper stock With a collecting agent, and a gelatinous material, reducing the paper stock With Water to a low density, adding a frothing agent, the relative amounts of paper stock and agents above named beingdetermined as hereinbefore described, producing frothing to effect flotationand thus the final separation of the inky froth from the paper stock, and removing the froth produced.
  • the process 0f de-inking imprinted paper which consists in defiberizing the stock, adding agents having detergent and collecting properties, cooking the paper stock until tests taken show the stock defiberized and the fiber substantially freed from ink particles, reducing the stock with water to low density, the relative amounts of stock and agents above named being determined as hereinbefore described, producing frothing inthe presence of a frothing agent, whereby to effect flotation and thus the final separation 0f the inky froth from the paper stock, controlling excessive frothing by a modifying agent, and removing the froth produced.

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US72757734 1934-05-25 1934-05-25 Process for deinking imprinted paper Expired - Lifetime US2005742A (en)

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US72757734 US2005742A (en) 1934-05-25 1934-05-25 Process for deinking imprinted paper
GB1707934A GB441331A (en) 1934-05-25 1934-06-08 Process for de-inking imprinted paper
FR793990D FR793990A (fr) 1934-05-25 1935-06-25 Procédé pour enlever les encres charbonneuses des papiers imprimés

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Cited By (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2725985A (en) * 1953-04-06 1955-12-06 Monsanto Chemicals Flotation of carbon black
US2757797A (en) * 1953-03-27 1956-08-07 Monsanto Chemicals Water treatment
US2765919A (en) * 1952-04-23 1956-10-09 Juell Fredrik Process for the separation of suspended material from water by flotation and apparatus therefor
US2959513A (en) * 1956-04-06 1960-11-08 Mead Corp Paper stock recovery process
US3069307A (en) * 1960-04-20 1962-12-18 Petrolite Corp Oxyalkylated phenol process
US3069308A (en) * 1960-04-20 1962-12-18 Petrolite Corp Oxyalkylated alcohol process
US3069306A (en) * 1960-04-20 1962-12-18 Petrolite Corp Oxyalkylated water process
US3098784A (en) * 1959-08-06 1963-07-23 Nat Gypsum Co Process of deinking printed paper
US3102065A (en) * 1961-03-22 1963-08-27 Virginia Chemicals & Smelting Method and composition for dispersing of pitch
US3141816A (en) * 1960-07-27 1964-07-21 Nalco Chemical Co Method of improving operational efficiency of white water recovery systems
DE1177465B (de) * 1959-03-12 1964-09-03 Voith Gmbh J M Flotationsmaschine
US3212916A (en) * 1957-09-25 1965-10-19 Commw Of Australia Method of developing electrostatic image with foam liquid developer
US3446696A (en) * 1962-05-09 1969-05-27 Evening News Publishing Co Method of de-inking with a non-ionic detergent
US3865719A (en) * 1971-12-09 1975-02-11 Escher Wyss Gmbh Flotation device for a fibrous suspension
US3994770A (en) * 1973-08-04 1976-11-30 J. M. Voith Gmbh Treatment of waste paper, especially to effect the recovery of clean fibers therefrom
US4013505A (en) * 1972-03-09 1977-03-22 Vyzkumny Ustav Papieru A Celulosy Method of deinking printed wastepapers
US4043908A (en) * 1975-03-11 1977-08-23 Kemanord Aktiebolag Process for cleaning of a dispersion of dispersed particles
US4076578A (en) * 1974-10-21 1978-02-28 Canadian Patents And Development Limited Ink removal from waste paper
US4190522A (en) * 1977-08-17 1980-02-26 J. M. Voith Gmbh Apparatus for purifying a suspension of fibrous material
US4231841A (en) * 1977-10-20 1980-11-04 Montedison S.P.A. Process for the de-inking of printed waste paper
US4332638A (en) * 1979-03-06 1982-06-01 J. M. Voith Gmbh Method and apparatus for the recovery of a suspension of fibrous material from mixed waste paper
US4343679A (en) * 1979-10-23 1982-08-10 Interox (Societe Anonyme) Process for reclaiming waste paper
US4376011A (en) * 1979-10-16 1983-03-08 Hoechst Aktiengesellschaft Process for removing pigments from waste paper
US5330655A (en) * 1992-07-30 1994-07-19 J.M. Voith Gmbh Method of regulating a flotation system with a primary and secondary stage
US5500082A (en) * 1993-04-26 1996-03-19 North Carolina State University Deinking of xerographic printed wastepaper using long chain alcohol
US5766448A (en) * 1996-09-25 1998-06-16 International Paper Company Pressure screening system for processing contaminated pulp fiber
US5876558A (en) * 1997-12-17 1999-03-02 Institute Of Paper Science And Technology, Inc. Froth flotation deinking process for paper recycling
US6227374B1 (en) * 1997-07-16 2001-05-08 Voith Sulzer Papiertechnik Patent Gmbh Process and floatation device for the removal of interfering materials from an aqueous fiber pulp suspension
US20030106843A1 (en) * 2000-02-15 2003-06-12 Jameson Graeme John Froth flotation process and apparatus
US20040256295A1 (en) * 2003-06-20 2004-12-23 Voith Paper Patent Gmbh Method and device for the flotation of contaminants from an aqueous fibrous suspension
US20060021916A1 (en) * 2004-07-06 2006-02-02 Voith Paper Patent Gmbh Method for the flotation of contaminants from an aqueous fibrous suspension
US20130105366A1 (en) * 2009-10-23 2013-05-02 Herbert Britz Method for removing solid matter from a fibrous material suspension by means of flotation

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1106592B (de) * 1958-12-17 1961-05-10 Friedrich Karl Sauer Verfahren zum Regenerieren von teer- und bzw. oder bitumenhaltigen Papierabfaellen oder Altpapieren
DE2904326C3 (de) * 1979-02-05 1982-05-13 Naamloze Vennootschap Papierfabriek Gennep, Gennep Verfahren und Vorrichtung zum Deinken von Faserstoffsuspensionen
GB0220602D0 (en) * 2002-09-05 2002-10-16 Salvtech Ltd A method of producing moulded products from waste paper
CN114890593B (zh) * 2022-04-08 2024-06-18 江阴市昕晔环境科技有限公司 一种造纸工业废水的处理方法

Cited By (34)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2765919A (en) * 1952-04-23 1956-10-09 Juell Fredrik Process for the separation of suspended material from water by flotation and apparatus therefor
US2757797A (en) * 1953-03-27 1956-08-07 Monsanto Chemicals Water treatment
US2725985A (en) * 1953-04-06 1955-12-06 Monsanto Chemicals Flotation of carbon black
US2959513A (en) * 1956-04-06 1960-11-08 Mead Corp Paper stock recovery process
US3212916A (en) * 1957-09-25 1965-10-19 Commw Of Australia Method of developing electrostatic image with foam liquid developer
DE1177465B (de) * 1959-03-12 1964-09-03 Voith Gmbh J M Flotationsmaschine
US3098784A (en) * 1959-08-06 1963-07-23 Nat Gypsum Co Process of deinking printed paper
US3069307A (en) * 1960-04-20 1962-12-18 Petrolite Corp Oxyalkylated phenol process
US3069308A (en) * 1960-04-20 1962-12-18 Petrolite Corp Oxyalkylated alcohol process
US3069306A (en) * 1960-04-20 1962-12-18 Petrolite Corp Oxyalkylated water process
US3141816A (en) * 1960-07-27 1964-07-21 Nalco Chemical Co Method of improving operational efficiency of white water recovery systems
US3102065A (en) * 1961-03-22 1963-08-27 Virginia Chemicals & Smelting Method and composition for dispersing of pitch
US3446696A (en) * 1962-05-09 1969-05-27 Evening News Publishing Co Method of de-inking with a non-ionic detergent
US3865719A (en) * 1971-12-09 1975-02-11 Escher Wyss Gmbh Flotation device for a fibrous suspension
US4013505A (en) * 1972-03-09 1977-03-22 Vyzkumny Ustav Papieru A Celulosy Method of deinking printed wastepapers
US3994770A (en) * 1973-08-04 1976-11-30 J. M. Voith Gmbh Treatment of waste paper, especially to effect the recovery of clean fibers therefrom
US4076578A (en) * 1974-10-21 1978-02-28 Canadian Patents And Development Limited Ink removal from waste paper
US4043908A (en) * 1975-03-11 1977-08-23 Kemanord Aktiebolag Process for cleaning of a dispersion of dispersed particles
US4190522A (en) * 1977-08-17 1980-02-26 J. M. Voith Gmbh Apparatus for purifying a suspension of fibrous material
US4231841A (en) * 1977-10-20 1980-11-04 Montedison S.P.A. Process for the de-inking of printed waste paper
US4332638A (en) * 1979-03-06 1982-06-01 J. M. Voith Gmbh Method and apparatus for the recovery of a suspension of fibrous material from mixed waste paper
US4376011A (en) * 1979-10-16 1983-03-08 Hoechst Aktiengesellschaft Process for removing pigments from waste paper
US4343679A (en) * 1979-10-23 1982-08-10 Interox (Societe Anonyme) Process for reclaiming waste paper
US5330655A (en) * 1992-07-30 1994-07-19 J.M. Voith Gmbh Method of regulating a flotation system with a primary and secondary stage
US5500082A (en) * 1993-04-26 1996-03-19 North Carolina State University Deinking of xerographic printed wastepaper using long chain alcohol
US5766448A (en) * 1996-09-25 1998-06-16 International Paper Company Pressure screening system for processing contaminated pulp fiber
US6227374B1 (en) * 1997-07-16 2001-05-08 Voith Sulzer Papiertechnik Patent Gmbh Process and floatation device for the removal of interfering materials from an aqueous fiber pulp suspension
US5876558A (en) * 1997-12-17 1999-03-02 Institute Of Paper Science And Technology, Inc. Froth flotation deinking process for paper recycling
US20030106843A1 (en) * 2000-02-15 2003-06-12 Jameson Graeme John Froth flotation process and apparatus
US7163105B2 (en) * 2000-02-15 2007-01-16 The University Of Newcastle Research Associates Limited Froth flotation process and apparatus
US20040256295A1 (en) * 2003-06-20 2004-12-23 Voith Paper Patent Gmbh Method and device for the flotation of contaminants from an aqueous fibrous suspension
US20060021916A1 (en) * 2004-07-06 2006-02-02 Voith Paper Patent Gmbh Method for the flotation of contaminants from an aqueous fibrous suspension
US20130105366A1 (en) * 2009-10-23 2013-05-02 Herbert Britz Method for removing solid matter from a fibrous material suspension by means of flotation
US8925728B2 (en) * 2009-10-23 2015-01-06 Voith Patent Gmbh Method for removing solid matter from a fibrous material suspension by means of flotation

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GB441331A (en) 1936-01-08
FR793990A (fr) 1936-02-05

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