WO1996033308A1 - Procede de reduction en pate - Google Patents

Procede de reduction en pate Download PDF

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Publication number
WO1996033308A1
WO1996033308A1 PCT/US1996/005450 US9605450W WO9633308A1 WO 1996033308 A1 WO1996033308 A1 WO 1996033308A1 US 9605450 W US9605450 W US 9605450W WO 9633308 A1 WO9633308 A1 WO 9633308A1
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WIPO (PCT)
Prior art keywords
lignin
fiber slurry
oxygen
pulp
situ
Prior art date
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PCT/US1996/005450
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English (en)
Inventor
James W. Jelks
Original Assignee
R-J Holding Company
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Publication date
Application filed by R-J Holding Company filed Critical R-J Holding Company
Priority to AU55581/96A priority Critical patent/AU5558196A/en
Publication of WO1996033308A1 publication Critical patent/WO1996033308A1/fr

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Classifications

    • 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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/006—Pulping cellulose-containing materials with compounds not otherwise provided for
    • 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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/04—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides
    • D21C3/16—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides nitrogen oxides; nitric acid nitrates, nitrites
    • 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
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/1063—Bleaching ; Apparatus therefor with compounds not otherwise provided for, e.g. activated gases
    • 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
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications

Definitions

  • the process of this invention relates to the pulping and bleaching of lignocellulosic materials in the absence of chlorine based bleaches.
  • Pulping is the changing of wood chips or other wood particulate matter to fibrous form to form pulp. Pulp is a material used in the manufacture of paper, paperboard, and other related materials. The material subjected to the pulping and bleaching process is sometimes referred to as the biomass. Chemical pulping requires cooking of the biomass in solution with a chemical and includes partial removal of the coloring matter such as lignin, which is typically associated with the biomass. Bleaching is the treatment of cellulosic fibers to remove or alter the coloring matter associated with the fibers to enhance the whiteness of the pulp and the resulting final product.
  • the commonly utilized chemical pulping processes are broadly classified as: (1) the soda process, (2) the sulfite process, and (3) the Kraft process, an alkali process similar to the soda process except sodium sulfide is added to the caustic soda used in the soda process.
  • Mechanical pulps are broadly classified as (1) groundwood, and (2) chip/refiner pulp. The mechanical pulps are also referred to as "high yield pulps.”
  • the Kraft process is practiced in a variety of well-known modifications.
  • the critical step in any pulping process is the dissolution of the lignins without weakening or destroying the cellulosic matrix that provides strength to the final product being manufactured.
  • Wood is comprised of two main components-a fibrous carbohydrate, i.e. , cellulosic portion, and a non-fibrous component.
  • the polymeric chains forming the fibrous cellulose portion of the wood are aligned with one another and form strong associated bonds with adjacent chains.
  • the non-fibrous portion of the wood comprises a three-dimensional polymeric material formed primarily of phenylpropane units, known as lignin. Part of the lignin is between the cellulosic fibers, bonding them into a solid mass, although a substantial portion of the lignin is also distributed within the fibers themselves.
  • wood For use in paper-making processes, wood must first be reduced to pulp.
  • Pulp may be defined as wood fibers capable of being slurried or suspended and then deposited upon a screen to form a sheet, i.e., of paper.
  • the methods employed to accomplish the pulping step usually involve either physical or chemical treatment of the wood, or a combination of these two treatments, to alter the wood's chemical form and to impart desired properties to the resultant product.
  • pulping techniques There are thus two main types of pulping techniques, i.e., mechanical pulping and chemical pulping.
  • mechanical pulping the wood is physically separated into individual fibers.
  • chemical pulping the wood chips are digested with chemical solutions to solubilize a portion of the lignin and thus permit its removal.
  • the soda process is well known in the art. It employs sodium hydroxide (NaOH) as the active reagent to break down the lignin and to assist in its removal.
  • NaOH sodium hydroxide
  • the Kraft process together with its numerous variations is the principal chemical process utilized in paper manufacturing.
  • the modified Kraft techniques can result in even less degradation in the polymeric structure of the cellulosic fibers during pulping and therefore the strength loss in the resultant paper product is diminished as compared to that occurring with the standard Kraft process.
  • One modified Kraft pulping process is known as "extended delignification", which is a broad term used in the art to encompass a variety of modified Kraft techniques, such as adding the pulping chemicals in a specific defined sequence, or at different locations within the digester apparatus, or at different time periods, or with a removal and reinjection of cooling liquors in a prescribed sequence, so as to more effectively remove a greater amount of lignin while reducing the severity of the pulping liquor's chemical attack on the cellulosic fibers.
  • Another modification of the Kraft process is the Kraft-AQ process, wherein a small amount of anthraquinone is added to the Kraft pulping liquor to accelerate delignification while limiting the attack upon the cellulosic fibers which comprise the wood.
  • Digestion of the wood by a Kraft or modified Kraft process results in the formation of a dark colored slurry of cellulose fibers known as "brownstock".
  • the dark color of the brownstock is attributable to the fact that not all of the lignin has been removed during digestion and has been chemically modified in pulping to form chromophoric groups.
  • the residue obtained from the washing process commonly referred to as black liquor, is collected, concentrated, and then incinerated in an environmentally safe manner in a recovery boiler.
  • the technique for the collection, concentration and burning of the black liquor is conventional and is well known in the art.
  • ozone may initially appear to be an ideal material for bleaching lignocellulosic materials
  • exceptional oxidative properties of ozone and its relative high cost have heretofore limited the development of satisfactory ozone bleaching processes for lignocellulosic materials, especially southern softwoods.
  • Ozone will readily react with lignin to effectively reduce the K No. ("Kappa number"), but it will also, under most conditions, aggressively attack the carbohydrate which comprises the cellulosic fibers and substantially reduce the strength of the resulting pulp.
  • K No. Kappa number
  • Ozone likewise, is extremely sensitive to process conditions such as pH with respect to its oxidative and chemical stability, and such changes can significantly alter the reactivity of ozone with respect to the lignocellulosic materials.
  • the normal permanganate test provides a permanganate or "K number” or “Kappa number” which is the number of cubic centimeters of tenth normal potassium permanganate solution consumed by one gram of oven dried pulp under specified conditions. It is determined by TAPPI Standard Test T-214.
  • pulp brightness This parameter is usually a measure of reflectivity and its value is expressed as a percent of some scale.
  • a standard method is GE brightness which is expressed as a percentage of a maximum GE brightness as determined by TAPPI Standard Method TPD-103.
  • U.S. Patent 4,076,579 discloses a treatment process for particulate lignocellulosic material whereby nitric oxide is added to said material which is then reacted with molecular oxygen to form nitric acid in situ. This reaction is followed by washing of the resulting material with alkali and extraction with alkali at a temperature of about 140°C to delignify the lignite cellulose and form pulp.
  • Patent 4,602,982 and 4,750,973 disclose a process for activating cellulose pulp by reacting the pulp with a gas comprising nitrogen dioxide and molecular oxygen in the presence of water and sodium nitrate. The operational use of nitric acid is also disclosed.
  • the second series of prior art references identifies methods of high consistency oxygen delignification using a low consistency alkali pretreatment.
  • This prior art disclosure relates to methods for treatment of wood pulp, and/or particularly to methods for oxygen delignification of the brownstock produced during standard pulping operations.
  • the prior art oxygen method comprises the oxygen based delignification of pretreated brownstock pulp followed by bleaching operations to increase the brightness of the pulps.
  • Patents directed to this ozone based lignocellulosic treatment operation are U.S. Patent Nos. 5,085,734; 5, 164,043; 5,164,044; 5,173,153; 5,174,861; 5,181,989; 5,211,811; 5,217,574; and 5,296,099.
  • the process of this invention (referred to generically herein as the "LM Process”) is based on proprietary processes that separate lignin from cellulose without the use of environmentally offensive chemicals. For example, in the Kraft process a sulfur compound
  • the LM Process does not use a sulfur compound to separate lignin from cellulose.
  • nascent oxygen refers to the atomic molecule of oxygen having an atomic weight of 15.9994, an atomic number of 8 and a valence of 2. Nascent oxygen is extremely reactive.
  • molecular oxygen refers to the molecule O 2 which is the natural gaseous form of oxygen. The O 2 molecule is relatively stable when compared to the O* .
  • ozone refers to the O 3 molecule which is also referred to as tri -atomic oxygen. Ozone is produced continuously in the outer layers of the atmosphere by the action of solar ultra-violet radiation on the oxygen (O 2 ) of the air.
  • Ozone is prepared by passing dry air between two plate electrodes connected to an alternating current source of several thousand volts.
  • Ozone is a bluish, explosive gas or liquid. It is a powerful oxidizing agent and is considered chemically unstable. Solutions containing ozone explode on warming. It has typically been felt that the use of ozone in a pulping type operation which generally requires heating would be difficult and dangerous due to the chemical instability of the ozone molecule.
  • the inventors have discovered that the in situ preparation of atomic or nascent oxygen is an effective way to utilize the chemical properties of the oxygen atom without at the same time exposing the users to a constant threat of explosion.
  • wood chips are first de-fiberated and then the proprietary lignin oxidation and extraction processes are employed (pre-hydrolysis) or pretreatment in hot water ( ⁇ 200°F) or hot dilute alkali, especially with annual plant fiber.
  • De-fiberated wood chips are required since the proprietary lignin oxidation step has limited penetrating ability and therefore in the preferred embodiment, thoroughly, evenly wetted fiber is required.
  • a wet slurry process unites active oxygen with the biomass, which selectively oxidizes the lignin in the de-fiberated material. The active oxygen is carried in the wet slurry so as to have uniform access to all of the biomass which selectively and equally reacts with the lignin.
  • the oxygen source is active agitation to evenly mix water, biomass and the oxygen- carrying medium. Excess water is removed from the oxygen-bearing reactant and biomass and the water is returned to the oxidation stage. The resulting product is a pulp equivalent to brown Kraft pulp.
  • the pulp is then bleached using elemental chlorine or various chlorine compounds (such as chlorine dioxide, sodium hypochlorite, calcium hypochlorite, etc.).
  • elemental chlorine such as chlorine dioxide, sodium hypochlorite, calcium hypochlorite, etc.
  • the equivalent pulp product is bleached using the proprietary lignin oxidation and extraction processes that do not require chlorine compounds.
  • the resulting bleached pulp is comparable to bleached Kraft pulp in strength and quality.
  • the lignin-modified pulp is treated with the proprietary oxidation step once more; however, the solutions and treatment are quite mild so as to react only with the remaining lignin, and not damage the fiber.
  • This step which can be repeated to sufficiently reduce the Kappa number to allow final bleaching by hydrogen peroxide (or comparably mild bleaching agent), is equivalent to conventional bleaching processes.
  • a 3-stage bleaching sequence of lignin modification/extraction/hydrogen peroxide or a 5 -stage bleaching process of lignin modification/extraction/lignin modification/extraction/hydrogen peroxide are equivalent to the conventional 3-stage and 5- stage bleaching sequences performed on Kraft pulp using chlorine compounds.
  • the non-pulp components that are extracted can be further processed rather than disposed of as wastes.
  • the hydrolysate extracted in the initial pre-hydrolysis process is primarily composed of 5-carbon sugars that can be fermented to ethanol using fermentation and distillation technologies known to Mr. Jelks.
  • Mr. Jelks the ideal facility using the Jelks' LM Process would produce both pulp and ethanol.
  • the lignin that is extracted has application as a fertilizer feedstock. In conventional processes, extracted lignin is used as boiler fuel; however, because the LM Process eliminates the need of a recovery boiler used in reclaiming spent chemicals (sodium sulfide), the oxidized lignin can be recovered and marketed.
  • the economics of utilizing the LM Process to produce pulp are significant.
  • the cost of using the LM Process to produce bleached pulp is compared to the cost of using chlorine compounds in the Kraft process, the cost of lignin modification using the LM Process is approximately one-fourth the cost of chlorine-equivalent pulp production.
  • the description above contemplates the production of pulp from woody chips or other virgin biomass.
  • the LM Process can also be applied to bleaching recovered waste paper. Accordingly, after waste paper has been de-inked, the LM Process removes residual lignin contained in the pulp, reducing the Kappa number of the recycled pulp to a bleachable value whereby finished bleaching can be accomplished using bleaching agents other than chlorine compounds.
  • the LM Process can be employed in a "greenfield" paper pulp facility or it can be the basis for retrofitting an existing facility to replace existing technology. The latter scenario should be particularly attractive for an existing facility that must comply with the federal government standards that will greatly restrict the discharge of the effluent generated by conventional technologies.
  • the economies of scale associated with the LM Process will allow for the cost effective facilities to be constructed with production capacities of 100 tons of pulp per day; whereas facilities using conventional processes are generally constructed to produce upwards of 1 ,000 tons of pulp per day due to the treatment of effluent.
  • Elimination of chlorine compounds by substituting the LM Process to modify and extract lignin in a conventional Kraft pulp mill would achieve significant cost savings in producing bleached pulp. Furthermore, lignin modification and extraction using the LM Process would eliminate bleaching effluent wastestreams from a Kraft pulp mill by allowing the bleaching effluent to go to the mill's evaporators rather than to a recovery boiler. In essence, the environmentally offensive wastes associated with conventional chemical pulping are eliminated by the LM Process, and offers a more cost effective way to produce and bleach pulp.
  • the extraction stage may comprise, in a further embodiment, combining the substantially delignified pulp with an effective amount of an alkaline material in an aqueous alkaline solution for a predetermined time and at a predetermined temperature correlated to the quantity of alkaline material to solubilize a substantial portion of any lignin which remains in the pulp. Thereafter, a portion of the aqueous alkaline solution may be extracted to remove substantially all of the solubilized lignin therefrom.
  • the next step in the method of the present invention concerns the portion of the bleaching process which primarily involves removal of the residual lignin from the brownstock pulp being processed.
  • this stage comprises an oxygen delignification step.
  • the solid materials removed in this stage are oxygenated materials which can, like the black liquor, be collected, concentrated, and then incinerated in an environmentally safe manner in a conventional recovery boiler.
  • the oxygen delignification step can be conducted in the manner which allows for the removal of increased percentages of the remaining lignin in the brownstock pulp without causing an unacceptable corresponding decrease in the viscosity of the pulp.
  • the process which has been identified is practiced by treating the brownstock pulp from the pulping process at low to medium consistency, as described below, with the required amount of alkali necessary for the oxygen delignification step so as to ensure uniform application of the alkali, and thereafter raising the consistency and delignifying at high consistencies.
  • the high consistency oxygen delignification step is preferably carried out in the presence of an aqueous alkaline solution at a pulp consistency of from about 25 % to about 35 % , and even more preferably, at about 27%.
  • This improved process allows for the removal of at least 60% of the residual lignin from the brownstock pulp, compared to the 45-50% removable with conventional oxygen delignification steps, without the heretofore expected undesirable decrease in the relative viscosity. Because of the unique process capabilities of this modified process, it clearly constitutes the preferred oxygen process for use in the method of this invention.
  • the treatment step of the modified lignin, nascent oxygen process (0*0 comprises substantially uniformly combining wood pulp, preferably Kraft brownstock pulp, with an aqueous alkaline solution while maintaining the consistency of the pulp at less than about 10% and preferably less than about 5% by weight.
  • the aqueous alkaline solution is preferably present in an amount sufficient to provide from about 0.5% to about 4% active alkali by weight after thickening based upon the oven dry pulp weight of the brownstock pulp, and even more preferably about 2.5% active alkali by weight after thickening based upon the oven dry weight of the brownstock pulp.
  • This step uniformly distributes the aqueous alkaline solution throughout the low consistency brownstock and ensures that substantially all the brownstock fibers are exposed to a uniform application of alkaline solution.
  • the brownstock pulp treated in this manner is not substantially delignified in the treatment step, but it is more effectively delignified in the subsequent high consistency oxygen delignification step than brownstock that is treated with alkaline solutions at high consistency according to the methods conventionally employed.
  • the localized inhomogeneities in the distribution of alkali in conventional high consistency pulp are avoided, thus eliminating attendant non-uniform oxygen delignification.
  • nascent oxygen "in situ" with the pulp combined with methods that have been developed to maintain pulp viscosity, and therefore pulp quality is the basis of a new pulp bleaching process. This process bleaches pulp to a given brightness at a lower cost than the conventional methods using chlorine and chlorine compounds. Quality of the pulp produced by generation of nascent oxygen in situ is equal or better than that conventionally produced insofar as it been observed. Nascent oxygen reacts with pulp in several ways, two, 2, of which are by:
  • Elemental chlorine as used in the chlorination stage of bleaching reacts by addition to certain positions on the six carbon ring portion of the lignin and by splitting and addition to the aliphatic groups binding the benzene rings forming chlorinated lignin which becomes soluble in heated caustic solution.
  • the extracted chlorinated lignin is removed by washing.
  • Hypochlorite 1 s release nascent oxygen in situ with pulp to accomplish one of the nascent oxidations of lignin that subsequently allow removal of the lignin, or destruction of the lignin color bodies.
  • the mechanism of generating and releasing nascent oxygen is as follows; carbon dioxide in the atmosphere reacts with calcium hypochlorite to form hypochlorous acid and calcium carbonate. The calcium carbonate precipitates and the precipitate is removed by filtering. Reaction is: (CaOCl + CO 2 + H 2 O — > CaCO 3 + HOC1).
  • Hypochlorous acid is unstable and breaks down into hydrochloric acid and Nascent oxygen, (HOC1 — > HC1 + O ).
  • O 3 is a source of nascent oxygen. (O 3 — > O 2 + O,).
  • Ozone is quite unstable, in fact explosive, and makes it difficult to get the nascent oxygen it releases "in situ" with the pulp. Accordingly, the use of Ozone requires some extraordinary mixing with the pulp when it, Ozone, is used as the source nascent oxygen for pulp makes nascent oxygen available in situ to accomplish pulp bleaching reactions.
  • Sunlight when in contact with bio-mass containing cellulose generates ozone in minute quantities which is the genesis of the ancient bleaching procedures primarily used to bleach linen.
  • splitting molecular oxygen Preferred method is to dissolve the splitting agent in the water forming a pulp slurry.
  • Molecular oxygen which can come from air, is then introduced into the pulp slurry that contains the splitting agent.
  • Nitric Oxide is such an agent. Nitric oxide is obtained by burning anhydrous ammonia with air in the presence of catalyst. (4NH 3 + 50 2 — > 4No -I- 6H 2 O). Nitric Oxide is sparingly soluble in water, but sufficiently so that when air is introduced into the pulp slurry with nitric oxide present nascent oxygen is released "in situ". (NO + O 2 — > NO 2 + O]);
  • Nitrosylsulfuric acid is another source of nascent oxygen and nitric oxide. Use of nitrosylsulfuric acid as a nascent oxygen and nitric oxide source which splits further added
  • pulps with a high nascent oxygen demand require that several applications, or sequences are performed.
  • Electrochemical generation of oxygen "in situ" with pulp in the presence of electrolyte (HC1 + H 2 O + 2e — > HOC1 + H 2 — > HC1 + O, + H ⁇ . Electrolytes other than hydrochloric acid that are chlorine free are known. Potassium manganate can be oxidized to potassium permanganate in an electrolytic cell . Potassium permanganate can be further electrolyzed to permanganic acid and potassium hydroxide. Permanganic acid will release nascent oxygen in situ with pulp which is another example of electrochemical oxidation.
  • the LM Process is based on the discovery that nascent (atomic) Oxygen generated in situ with a cellulose pulp slurry will selectively oxidize any lignin present in the said pulp slurry. It has been observed that the viscosity of the pulp will be significantly lowered by this treatment.
  • lignin present with cellulose in a pulp slurry is selectively oxidized with nascent, (atomic) oxygen without significant loss, or loss of viscosity when the pH is maintained at about lO ⁇ in the presence of a magnesium salt or salts.
  • Said oxidized lignin in the pulp is soluble in a dilute alkaline solution which allows the production of pulp with very low Kappa numbers with high viscosity value. This type of pulp posses very high strength characteristics.
  • the resulting pulp is very responsive to various bleaching procedures.
  • nascent, (atomic) oxygen is the ability of nitric oxide to split the oxygen molecule, (O- 2 ), NO + O 2 — > NO 2 + O,.
  • anhydrous ammonia's combustion with oxygen in the presence of a catalyst is a low cost method of producing nitric oxide, 4NH 3 + 50 ⁇ — > 4NO + 6H 2 O.
  • One mole of catalytically oxidized anhydrous ammonia therefore produces one mole nascent, atomic oxygen at 100% efficiency.
  • Cost of anhydrous is generally in the range of 7'/ 2 C to 8C per pound. Economics of this reaction is enhanced by the fact that the combustion of anhydrous ammonia produces significant heat that must be immediately removed from the gasses produced by this combustion.
  • nascent, atomic oxygen The oxidation of lignin by nascent, atomic, oxygen is equivalent to the lignin modification of 4.432 pounds of chlorine, i.e., .226# of nascent oxygen is equivalent to 1# of element chlorine.
  • a fiber protecting additive is used.
  • the preferred additive is magnesium hydroxide.
  • Magnesium requirement when magnesium hydroxide, Mg(OH) 2 is calculated on supplying 10% more than the acid formed by the nitrogen oxide acids formed, i.e., 110% mole basis of NO used.
  • Mole equivalent of calcined dolomite produces essentially the same result at a very low cost.
  • the LM Process is limited in so far as penetration of wood chips is concerned. Accordingly, the Process requires that de-fiberized or pulped lignin containing fiber be treated. Pulping application requires a fiber slurry with lignin content for the practice of the LM Process.
  • the lignin in the slurry is oxidized with nascent oxygen generated in the said slurry with certain fiber protecting additives controlled at a specified pH to maintain "high pulp viscosity".
  • the oxidized lignin formed is removed by dilute alkali extraction.
  • Very high Kappa number pulp is reduced to a pulp with a very low Kappa number, (5 or less) while essentially maintaining its original viscosity by repetition of the above procedure, lignin oxidation followed by alkali extraction.
  • Bleaching application is accomplished by removal of residual lignin left in the pulp to a level that will allow nascent oxygen to act as a bleach, (destruction of color bodies by oxidation).
  • Conversion of pulp mill sludge to a saleable commodity is accomplished by oxidizing the lignin in the fiber in the sludge slurry with nascent oxygen so as to allow the carbohydrate, (cellulose) to be hydrolyzed into fermentable sugars.
  • the resulting sugars are separated from the inorganic solids.
  • the resulting dilute sugar solution is evaporated into a fermentable sugar containing molasses.
  • This molasses can be sold for a substrate for fermentation to alcohol, or as the substrate for the production of antibiotic producing fungus or other biological application.
  • the relative small volume of remaining lignin can be burned leaving only ash to be land filled.
  • Magazines and other coated grades of waste paper were the major source of recycled fibers but are no longer de-inked because of a significant increase of lignin content from high lignin content pulps like ground wood which are now a part of white coated papers such as magazines.
  • High lignin content pulp is not suitable for the manufacture of stable bright white papers. That excess lignin can now be removed by the LM Process and this former source of high grade used fiber can again be recovered. Magazines and other high filler content waste paper results in the production of excessive amounts of de-ink sludge.
  • nascent oxygen generated in a slurry remaining organic material at low ambient (atmospheric) pressure resulting in a white reclaimed mostly clay comprised filler. The result is a saleable white filler and the near elimination of the solid waste leaving only a small amount of ash requiring landfill.
  • the process and chemicals disclosed can be effectively used to reclaim filler materials and bleaching materials from the pulped biomars.
  • the fibers obtained by the oxidative delignification process show low opacity values.
  • Use of filler materials such as magnesium hydroxide and/or other magnesium salts have demonstrated the capability of maintaining the high viscosity of cellulose that is exposed to nascent oxygen pulping and bleaching.
  • Figure 1 is a flow chart illustrating schematically the steps in the process of this invention.
  • the beginning material for application of the process of this invention is a biomass of lignin containing cellulosic material.
  • Sources of such material are recycled paper, recycled paperboard, kenaf, wheat straw, hemp, pulp wood, or other annual plants, and combinations thereof. Any of the traditional sources for cellulosic fiber used for the manufacture of paper or paper related products can be used as the source for the biomass 10 of this invention.
  • the biomass 10 is placed in a mixing apparatus 20 wherein various fluids are added to convert the biomass into a fiber slurry 30.
  • the biomass may be physically or chemically mixed to form a fiber slurry.
  • water is added to the biomass in the mixing apparatus together with a fiber protecting additive.
  • the preferred fiber protecting additive is magnesium hydroxide.
  • the resulting slurry is transferred to a reactor vessel 30 where it undergoes further treatment.
  • the mixing apparatus 20 and reactor vessel 30 are combined as a single piece of hardware.
  • the fiber slurry is exposed to nascent oxygen formed in situ. The nascent oxygen selectively delignifies the fiber slurry by oxidation.
  • nascent oxygen is formed by a number of known chemical reactions.
  • nitric oxide is produced by the combination of anhydrous ammonium and molecular oxygen, or molecular oxygen from atmospheric air.
  • the nitric oxide reaction product is then reacted with molecular oxygen to form nascent oxygen in situ.
  • a variant of the reaction NO + O 2 — > NO 2 + ⁇ ! is the use of nitrosylsulfuric acid as a source of nascent oxygen and nitric oxide which will produce more nascent oxygen from molecular oxygen when supplied.
  • the nascent oxygen is produced in situ by the addition of hypochlorous acid to the fiber slurry.
  • the hypochlorous acid is produced by dissolving calcium hypochlorite in water, precipitating the calcium with carbon dioxide to produce calcium carbonate and hypochlorous acid, and by then adding the hypochlorous acid to the fiber slurry to release nascent oxygen in situ.
  • nascent oxygen is produced in situ by producing hypochlorous acid in situ as the reaction product of sodium hypochlorite with hydrochloric acid.
  • the hypochlorous acid of this embodiment may be produce in situ by the electrolytic oxidation of hydrochloric acid, and then by the addition of the hydrochlorous acid to the fiber slurry to release nascent oxygen in situ.
  • Nitric acid may be produced in situ by the addition of the reaction product of nitric oxide and molecular oxygen.
  • the nascent oxygen is produced in situ by the addition of permanganic acid to the fiber slurry. In a further embodiment the nascent oxygen is produced in situ by the addition of percarbonic acid to the fiber slurry.
  • the resulting fiber slurry is washed to dispose of lignin and other chemicals that are present.
  • an acetic wash fluid is used.
  • the preferred acid is nitric acid in combination with water.
  • Other materials well-known in the paper making art are equally useful in this particular washing step.
  • the extraction zone 50 results in the creation of a pulp product from which lignin has been selectively removed but wherein the strength of the cellulosic fiber matrix has not been significantly adversely effective.
  • the pulp biomass is sent to a second wash zone 60.
  • the second wash zone 60 is typically a hot water wash zone resulting in a washer effluent with remaining chemicals, including lignin.
  • the finished pulp 70 is recovered for use in the manufacturer of a final product.
  • the finished pulp 70 may be recycled through the steps represented by reactor 30, wash 40, extraction 50, and wash 60 to achieve the desired final pulp product.
  • non-elemental chlorine products that have shown utility in bleaching the product of this invention are chlorine dioxide, hypochlorite, and combinations thereof.
  • nitrosylsulfuric acid HNOSO 4
  • nitrogen dioxide and sulfuric acid may be beneficially used in the creation of nascent oxygen in the process of this invention.
  • An alternative method for creating the nitrosylsulfuric acid is the reaction of sulfur dioxide with nitric acid. Use of this material would be beneficial to the preservation of the viscosity of the original biomas slurry.
  • Figure 1 is a process diagram showing how sample P 4 was made. This sample demonstrates the potential for replacing chlorine or chlorine - chlorine dioxide in the first stage of Kraft pulp bleaching stages. In this instance the nascent oxygen requirements was calculated on the chlorine and chlorine dioxide normally used for delignification of extended cooked Kraft pulp.
  • a modified Cusinart food processor was used to mix water and magnesium hydroxide with the pulp to be subjected to selective lignin oxidation.
  • a vacuum reactor was used in lieu of a mechanical mixer for the actual selective lignin oxidation. This reactor was made from a modified aluminum steam pressure cooker equipped with a stainless steel liner that contained the "mixed pulp”. The vacuum reactor is fitted with a manifold, valves, pressure gauge, vacuum gauge, nitric oxide connection, oxygen connection necessary to provide quick access to accomplish the steps that follow.
  • nitric oxide/oxygen addition was divided into three additions into the reactor. Each nitric oxide addition was followed by adding excess oxygen to the reactor to 2 atm. absolute, (approximately 15 psig). A vacuum was accomplished prior to each nitric oxide addition. Amount of nitric oxide was determined by difference in vacuum measurement on the basis of net volume in the reactor.
  • NO- 2 effluent, acid effluent, hot water wash effluents would be manipulated so as to lower costs in commercial practice.
  • the NO 2 would be condensed by cooling the effluent. It would be combined with the "acid effluent" and part of the washed effluent and compressed air which would convert the effluents to a mixture of nitric and nitrous acids that would be used for the acid wash at essentially "no cost”. Excess was effluent would go to the evaporators and on to the recovery boiler.
  • Reactions with nitrosylsulfuric acid are: 1) synthesis of nitrosylsulfuric acid; 2H 2 S0 4 + 2NO + iQ ⁇ — > 2HNOSO 4 -I- H,O. 2) Reactions with moist pulp: 2HNOSO 4 -I- H 2 O — > 2H 2 SO 4 -I- 2NO + O, followed by 2NO + 2O 2 + 2O,.

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Abstract

Cette invention concerne un processus préférable sur le plan de l'environnement et destiné à la délignification d'une biomasse cellulosique. Ce processus fait appel aux propriétés oxydantes de l'oxygène naissant afin d'effectuer des opérations de réduction en pâte et de blanchiment. Ce processus peut être appliqué soit seul, soit en combinaison avec d'autres processus de traitement.
PCT/US1996/005450 1995-04-20 1996-04-19 Procede de reduction en pate WO1996033308A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU55581/96A AU5558196A (en) 1995-04-20 1996-04-19 Pulping process

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US42649995A 1995-04-20 1995-04-20
US08/426,499 1995-04-20

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WO1996033308A1 true WO1996033308A1 (fr) 1996-10-24

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7585387B2 (en) 2005-03-11 2009-09-08 Board Of Supervisors Of Louisiana State University And Agricultural And Mechanical College Chemical oxidation for cellulose separation with a hypochlorite and peroxide mixture
WO2009138090A2 (fr) * 2008-05-14 2009-11-19 Rådet For Agroindustri Procédé pour la fabrication de matière végétale hydrolysée
WO2009140808A1 (fr) * 2008-05-20 2009-11-26 Li Gangrong Procédé et système de fabrication de pâte à papier de type en boucle non polluant, respectueux de l’environnement et à économie d’énergie
WO2011156708A1 (fr) * 2010-06-10 2011-12-15 Packaging Corporation Of America Procédé de fabrication de pâte pour support ondulé
CN111315802A (zh) * 2017-11-07 2020-06-19 英格维蒂南卡罗来纳有限责任公司 制备低色木质素的方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2255418A1 (fr) * 1973-12-21 1975-07-18 Europeen Cellulose
US4002526A (en) * 1975-10-10 1977-01-11 International Paper Company Oxygen-alkali delignification of low consistency wood pulp
US4076579A (en) * 1973-08-06 1978-02-28 The Regents Of The University Of California Pulping of lignocellulosic material by sequential treatment thereof with nitric oxide and oxygen
US4294654A (en) * 1980-03-21 1981-10-13 International Paper Company Delignification and bleaching of lignocellulosic pulp via photo-oxygenation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4076579A (en) * 1973-08-06 1978-02-28 The Regents Of The University Of California Pulping of lignocellulosic material by sequential treatment thereof with nitric oxide and oxygen
FR2255418A1 (fr) * 1973-12-21 1975-07-18 Europeen Cellulose
US4002526A (en) * 1975-10-10 1977-01-11 International Paper Company Oxygen-alkali delignification of low consistency wood pulp
US4294654A (en) * 1980-03-21 1981-10-13 International Paper Company Delignification and bleaching of lignocellulosic pulp via photo-oxygenation

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7585387B2 (en) 2005-03-11 2009-09-08 Board Of Supervisors Of Louisiana State University And Agricultural And Mechanical College Chemical oxidation for cellulose separation with a hypochlorite and peroxide mixture
WO2009138090A2 (fr) * 2008-05-14 2009-11-19 Rådet For Agroindustri Procédé pour la fabrication de matière végétale hydrolysée
WO2009138090A3 (fr) * 2008-05-14 2010-01-07 Rådet For Agroindustri Procédé pour la fabrication de matière végétale hydrolysée
WO2009140808A1 (fr) * 2008-05-20 2009-11-26 Li Gangrong Procédé et système de fabrication de pâte à papier de type en boucle non polluant, respectueux de l’environnement et à économie d’énergie
WO2011156708A1 (fr) * 2010-06-10 2011-12-15 Packaging Corporation Of America Procédé de fabrication de pâte pour support ondulé
US8961740B2 (en) 2010-06-10 2015-02-24 Packaging Corporation Of America Method of manufacturing pulp for corrugated medium
US9399835B2 (en) 2010-06-10 2016-07-26 Packaging Corporation Of America Method of manufacturing pulp for corrugated medium
CN111315802A (zh) * 2017-11-07 2020-06-19 英格维蒂南卡罗来纳有限责任公司 制备低色木质素的方法

Also Published As

Publication number Publication date
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