US2976273A - Treatment of kraft black liquor and product - Google Patents

Treatment of kraft black liquor and product Download PDF

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Publication number
US2976273A
US2976273A US760185A US76018558A US2976273A US 2976273 A US2976273 A US 2976273A US 760185 A US760185 A US 760185A US 76018558 A US76018558 A US 76018558A US 2976273 A US2976273 A US 2976273A
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black liquor
sulfur
lignin
liquor
content
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US760185A
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English (en)
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Frank J Ball
Pueschel Richard
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West Virginia Pulp and Paper Co
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West Virginia Pulp and Paper Co
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Priority to US760185A priority Critical patent/US2976273A/en
Priority to AT661059A priority patent/AT240686B/de
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
    • C08H6/00—Macromolecular compounds derived from lignin, e.g. tannins, humic acids
    • 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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/0007—Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for

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  • This invention relates to a process for treating residual black liquor from the kraft pulping process whereby dimethyl sulfide is produced, lignin contained in the black liquor is modified and the aliphatic acid content in the black liquor is substantially increased.
  • methoxy groups are removed from the lignin. These methoxy groups react with the sulfur compounds within the liquor to form the dimethyl sulfide. Besides beingdemethylated the lignin also undergoes other changes which are not fully understood but which result in a substantial increase kin the concentration of certain low molecular weight aliphatic acids, such as acetic, propionic, glycolic, oxalic, and lactic acids, which acids will be referred to as aliphatic acids throughout the disclosure and claimsof this specification, and a considerable reduction in the pH of the liquor. These changes and their ⁇ significance will Vbe more fully shown after the following descriptionl of the complete process of this invention.
  • This black liquor may be obtained from the digesters, the washers, lthejevaporators or any source.
  • the liquor be concentrated to a solids content of greater than about These reasons are to reduce the heat require-V ficulties encountered in handling the liquor.
  • a partially concentrated black liquor yfrom the kraft pulping of pine wood from which the talloil skimmings have been removed may contain 30-l35% solids and have a sulfidic sulfur content of 4 ton6 Vg./l.
  • the pressure is relieved, the liquor being allowed to pass via coolers to a receiver Where it should arrive with a temperature near the boiling point of the black liquor at atmospheric pressure.
  • the more volatile components of the liquor particularly the dimethyl sulfide is flashed into vapor.
  • the part of the liquor which remains. liquid is collected and discharged under suitable control to a filter, being aciditied enroute to the lter to cause precipitation of the lignin and liberation of the aliphatic acids from their salts.
  • the precipitated lignin is then recovered by filtration.
  • the filtrate from which the lignin has been removed is subjected to a process, such as liquid extraction, for separating the aliphatic acids.
  • a two stage acidification process may be used resulting in savings in acid.
  • the liquor is acidified to a pH of approximately 9.5 which will cause approximately 95% of the lignin to be precipitated.
  • the liquor is further acidiied to precipitate the final quantities of lignin and to produce the aliphatic acids from their salts.
  • the vapors and gases ashed from the liquor are conducted to a cooler where the noncondensible gases, such as carbon dioxide, are removed and the condensable dimethyl sulfide and water vapor condensed.
  • the water and dimethyl sulfide being practically mutually immiscible, form two layers with the dimethyl sulfide floating on the aqueous condensate.
  • the dimethyl sulfide is separated from the water by decantation to obtain a crude dimethyl sulde. Pure dimethyl sulfide 4is then obtained by distillation of the crude dimethyl sulfide.
  • a very significant effect of the reaction as carried out according to this invention in relation to the recovery of lignin and aliphatic acids is the lowering of the pH.
  • the pH of the liquid fraction has been found to decrease as much as 2.5 pH units during the heating of the liquor.
  • a higher percentage of the lignin may thus be precipitated with the same addition of acid now used for precipitating lignin from untreated black liquor or the same percentage of lignin may be precipitated with a lesser addition of acid. In either case an economy is realized. Also more aliphatic acids are liberated with the same quantity of acid.
  • the moist sodium salt of this modified lignin has been found to be a very effective oxygen-scrubber. In most applications where normal lignin is used this modified lignin may also be used more easily or effectively.
  • the chemical structure of the lignin produced by this process will vary considerably with the conditions under which the black liquor is treated.
  • the modified lignin from kraft pulped pine will contain 0.1 to 12% by Weight of methoxy groups compared to 13 to 15% for normal kraft pine lignin, 0.5 to 2% of sulfur compared to 1.0 to 3.0% for normal kraft pine lignin, and up to 50% more acidic groups than normal kraft pine lignin.
  • the lignin of this process has a wide range of molecular weights whereas normal kraft pine lignin has a very uniform molecular size.
  • pine lignin modified by this process has greater solubility in many organic solvents such as ethanol, hexanol, methyl acetate, acetone, epichlorohydrine, dioxane, triethylphosphate, dimethyl sulphone, and mixtures such as 1:1 methanol-benzene, increased reactivity with organic and inorganic compounds such as formaldehyde and oxygen, a more spherical particle shape, and a much greater ether extractibility, up to 30% while normal lignin has no ether extractibility.
  • organic solvents such as ethanol, hexanol, methyl acetate, acetone, epichlorohydrine, dioxane, triethylphosphate, dimethyl sulphone, and mixtures such as 1:1 methanol-benzene
  • the lignins from this process are greatly superior to lignins modified by the methods of Hagglund and Cisney which contain high percentages of sulfur, up to 15%, and have little if any solubility in most organic solvents.
  • the modified lignins produced by the process of this invention will form salts. All substances which will form salts with normal lignin will also form a salt with the modified lignin by the same processes. For instance, by precipitating the modified lignin from the black liquor at high pH, about 9.0 to 10.0, the sodium salt is obtained.
  • Other modified lignin salts can be obtained by the same method generally used in producing normal lignin salts, i.e. by reacting lignin in solution at a proper pH with thc appropriate positive ion and precipitating the lignin salt formed at a pH above that at which the salt will be decomposed.
  • Example 1 Concentrated black liquor from a kraft cook of pine wood containing 35 .35 solids after skimming off of the tall oil soaps was heated to 1) 220 C. and held at that temperature for (2) 36 minutes under a pressure of (3) 800 p.s.i. This heating lowered the pH of the liquor from 11.90 to (4) 11.15. This liquor was ashed to remove gases and vapors and the pH of the liquid fraction was reduced to 9.5 by the addition of (5) 85 ml. of 31 B. sulfuric acid for precipitating the major portion of the lignin. The liquor was filtered and acidifed again to precipitate the remaining lignin and to liberate the aliphatic acids from their salts.
  • the liquor was again filtered to remove the lignin precipitated and the aliphatic acids were extracted.
  • the total yields of dry lignin and pure dimethyl sulfide expressed as percentages of black liquor solids were, respectively, (6) 34.5 and (8) 0.22.
  • the percentage reduction of the methoxy groups on the lignin was (9) 12%.
  • Example l The details of Example l are tabulated below together 6 vthe order of one-quarter hour totwo hours while maintaining it under a pressure which is at all times at least las great as the vapor pressure of the black liquor at the existing temperature of the black liquor, thereby producwith corresponding details of Examples 2 to 8.
  • Ex- 5 ing a quantity of dimethyl sulfide whose lsulfur content is amples 2 through 8 the starting material and procedure derived chiefly from the initially non-sulfidic sulfur and were the same as for Example l with the exception of the exceeds the total initial sulfidic sulfur content of the black indicated variations. liquor, an increased yield of low molecular weight alidemand Lig-nin Aliphatic DMS Percent Example Temp., Time, Pressure, Dep. perliter Yield, acid Yield, Red.
  • the method of treating residual black liquor of the kraft pulping process having a small initial ratio of sulfldic sulfur to total solids inherently present and a considerably larger initial ratio of chemically combined, nonsulfidic sulfur to total solids inherently present which comprises heating such black liquor, concentrated to a solids content of 25 to 60%, to, and maintaining itin, the range of 220 to 350 C. under a pressure which is at all times at least as great as the vapor pressure of the black liquor at the existing temperature of the black liquor, thereby producing a quantity of dimethyl sulfide whose sulfur content is derived chiefly from the initially non-sullidic sulfur of the black liquor, and separating and recovering from the back liquor the dimethyl sulfide so produced.
  • the method of treating residual black liquor of the kraft pulping process having a small initial ratio of suldic sulfur to total solids inherently present and a considerably larger initial ratio of chemically combined, nonsuliidic sulfur to total solids inherently present which comprises heating such black liquor, concentrated to a solids content of 25 to 60%, to, and maintaining it in, the range of 220 to 350 C.
  • the method of treating residual black liquor of the kraft pulping process having a small initial ratio of sulfidic sulfur to total solids inherently present and a considerably larger initial ratio of chemically combined, nonsuliidic sulfur to total solids inherently present which comprises heating the black liquor, concentrated to a solids content of 25 to 60%, to 220 to 350 C. and maintaining it in that temperature range for a period of ing from the black liquor a desired product so produced.
  • an increased yield of aliphatic acids which method cornprises heating the black liquor, concentrated through evaporation to a solids content yof 25 to 60%, to the range of 220 to 350 C. ⁇ and maintaining it in said range for a period of the order of one-quarter hour to two hours, while maintaining it under pressure which is at all times ⁇ at least as great as the vapor pressure of the black liquor at the existing temperature Iof the black liquor, thereby producing dimethyl sulfide whose sulfur content is derived chiefly from the initially non-suliidic sulfur and exceeds the initial sulfidic sulfur content of the black liquor, reducing the pressure on the heated black liquor to a pressure not substantially above atmospheric pressure to cause flashing of vapors from the black liquor at a temperature not substantially above the atmospheric boiling point of the black liquor, separating the flashed vapors from the liquid fraction, acidifying the liquid fraction to cause the precipitation of the lignin and conversion of aliphatic acid salts into aliphatic acids, filtering out the
  • a modified lignin product obtained from black liquor from the kraft process of pulping wood having a small initial ratio of sullidic sulfur to total solids inherently present and a considerably larger initial ratio of chemically combined non-sulidic sulfur to total solids inherently present, by heating such black liquor, concentrated to a solids content of 25 to 60%, to, and maintaining it in, the range of 220 to 350 C. under a presprecipitate the modified lignin product therefrom, said modified product being characterized by having a1 sulfur content between 0.5 and 2.0% by weight and having,

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biochemistry (AREA)
  • Materials Engineering (AREA)
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US760185A 1958-09-10 1958-09-10 Treatment of kraft black liquor and product Expired - Lifetime US2976273A (en)

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US760185A US2976273A (en) 1958-09-10 1958-09-10 Treatment of kraft black liquor and product
AT661059A AT240686B (de) 1958-09-10 1959-09-10 Verfahren zur Behandlung von Schwarzlaugen aus der Kraft-Zellstoff-Herstellung

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937647A (en) * 1972-12-11 1976-02-10 Svenska Traforskningsinstitutet Method of increasing cellulosic pulp yields in an alkaline digestion process
US3948801A (en) * 1972-09-14 1976-04-06 Westvaco Corporation Stabilizer composition of phosphite and lignin
US4584057A (en) * 1985-04-22 1986-04-22 The United States Of America As Represented By The Secretary Of Agriculture Membrane processes for separation of organic acids from kraft black liquors
US4764597A (en) * 1987-06-15 1988-08-16 Westvaco Corporation Method for methylolation of lignin materials
US5021531A (en) * 1989-04-03 1991-06-04 Colorado State University Research Foundation Method for recovering and using lignin in adhesive resins by extracting demethylated lignin
US5026808A (en) * 1989-04-03 1991-06-25 Colorado State University Research Foundation Method for recovering and using lignin in adhesive resins by extracting demethylated lignin
US5177169A (en) * 1989-04-03 1993-01-05 Colorado State University Research Foundation Method for recovering and using lignin in adhesive resins
US5480512A (en) * 1990-07-09 1996-01-02 A. Ahlstrom Corporation Method of controlling sulfidity of a sulfate pulp mill
WO2000017444A1 (en) * 1998-09-24 2000-03-30 Kurple Kenneth R Pulping process without a recovery furnace
US20030056910A1 (en) * 2001-09-24 2003-03-27 Mullen Walter Thomas Method to lower the release of hazardous air pollutants from kraft recovery process
US20060254733A1 (en) * 2001-09-24 2006-11-16 Dunn Jerry P Method to lower the release of hazardous air pollutants from Kraft recovery process
US20080047674A1 (en) * 2004-09-14 2008-02-28 Fredrik Ohman Method for Separating Lignin from Black Liquor
US20080051566A1 (en) * 2004-10-07 2008-02-28 Fredrik Ohman Method For Separating Lignin From A Lignin Containing Liquid/Slurry
US8709204B1 (en) * 2013-03-14 2014-04-29 Veolia Water Solutions & Technologies North America Inc. System and process for recovering heat from weak black liquor in a wood pulping process
WO2018115592A1 (en) * 2016-12-21 2018-06-28 Teknologian Tutkimuskeskus Vtt Oy Method for producing reactive lignin
SE2050074A1 (en) * 2020-01-28 2021-01-29 Soedra Skogsaegarna Ekonomisk Foerening Process for producing one, or more, compounds
WO2024187276A1 (en) * 2023-03-14 2024-09-19 Fpinnovations Improved process for the extraction of kraft lignin from hardwood and eucalyptus black liquors

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1638061A (en) * 1923-06-06 1927-08-09 Rinman Erik Ludvig Method of dry distillation of alkalized waste liquor from the soda cellulose manufacture
US2505457A (en) * 1947-06-19 1950-04-25 Nat Aluminate Corp Method of inhibiting scale
US2505304A (en) * 1947-06-19 1950-04-25 Marathon Corp Lignin compounds and method for making same
CA466610A (en) * 1950-07-18 Olof Vidar Bergstrom Hilding Process of utilizing waste liquors
USRE24293E (en) * 1957-03-19 Method of improving the yield of

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA466610A (en) * 1950-07-18 Olof Vidar Bergstrom Hilding Process of utilizing waste liquors
USRE24293E (en) * 1957-03-19 Method of improving the yield of
US1638061A (en) * 1923-06-06 1927-08-09 Rinman Erik Ludvig Method of dry distillation of alkalized waste liquor from the soda cellulose manufacture
US2505457A (en) * 1947-06-19 1950-04-25 Nat Aluminate Corp Method of inhibiting scale
US2505304A (en) * 1947-06-19 1950-04-25 Marathon Corp Lignin compounds and method for making same

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3948801A (en) * 1972-09-14 1976-04-06 Westvaco Corporation Stabilizer composition of phosphite and lignin
US3937647A (en) * 1972-12-11 1976-02-10 Svenska Traforskningsinstitutet Method of increasing cellulosic pulp yields in an alkaline digestion process
US4584057A (en) * 1985-04-22 1986-04-22 The United States Of America As Represented By The Secretary Of Agriculture Membrane processes for separation of organic acids from kraft black liquors
US4764597A (en) * 1987-06-15 1988-08-16 Westvaco Corporation Method for methylolation of lignin materials
US5021531A (en) * 1989-04-03 1991-06-04 Colorado State University Research Foundation Method for recovering and using lignin in adhesive resins by extracting demethylated lignin
US5026808A (en) * 1989-04-03 1991-06-25 Colorado State University Research Foundation Method for recovering and using lignin in adhesive resins by extracting demethylated lignin
US5177169A (en) * 1989-04-03 1993-01-05 Colorado State University Research Foundation Method for recovering and using lignin in adhesive resins
US5480512A (en) * 1990-07-09 1996-01-02 A. Ahlstrom Corporation Method of controlling sulfidity of a sulfate pulp mill
WO2000017444A1 (en) * 1998-09-24 2000-03-30 Kurple Kenneth R Pulping process without a recovery furnace
US20060254733A1 (en) * 2001-09-24 2006-11-16 Dunn Jerry P Method to lower the release of hazardous air pollutants from Kraft recovery process
US20030056910A1 (en) * 2001-09-24 2003-03-27 Mullen Walter Thomas Method to lower the release of hazardous air pollutants from kraft recovery process
US20080047674A1 (en) * 2004-09-14 2008-02-28 Fredrik Ohman Method for Separating Lignin from Black Liquor
US8486224B2 (en) * 2004-09-14 2013-07-16 Lignoboost Ab Method for separating lignin from black liquor
US20080051566A1 (en) * 2004-10-07 2008-02-28 Fredrik Ohman Method For Separating Lignin From A Lignin Containing Liquid/Slurry
US8815052B2 (en) * 2004-10-07 2014-08-26 Lignoboost Ab Method for separating lignin from a lignin containing liquid/slurry
US8709204B1 (en) * 2013-03-14 2014-04-29 Veolia Water Solutions & Technologies North America Inc. System and process for recovering heat from weak black liquor in a wood pulping process
WO2018115592A1 (en) * 2016-12-21 2018-06-28 Teknologian Tutkimuskeskus Vtt Oy Method for producing reactive lignin
EP3559014A4 (de) * 2016-12-21 2020-07-15 Teknologian Tutkimuskeskus VTT Oy Verfahren zur herstellung von reaktivem lignin
SE2050074A1 (en) * 2020-01-28 2021-01-29 Soedra Skogsaegarna Ekonomisk Foerening Process for producing one, or more, compounds
WO2021154143A1 (en) 2020-01-28 2021-08-05 Södra Skogsägarna Ekonomisk Förening Method and process plant for treatment of a stream of mixed compounds
WO2024187276A1 (en) * 2023-03-14 2024-09-19 Fpinnovations Improved process for the extraction of kraft lignin from hardwood and eucalyptus black liquors

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AT240686B (de) 1965-06-10

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