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
  • D21C3/22—Other features of pulping processes
  • D21C3/222—Use of compounds accelerating the pulping processes

Definitions

• anthraquinone, certain anthraquinone derivatives and certain diketohydroanthracenes have a beneficial effect on certain processes for the recovery and bleaching of pulp from lignocellulosic materials such as wood, straw and bagasse when used in an amount of 0.001 to 10% by weight, based on the lignocellulosic material.
• anthraquinone anthrahydroquinone and Diels-Alder adducts from butadiene and its derivatives with p-benzoquinone or 1,4-naphthoquinone
• the mono- and polyalkyl, alkoxy, amino, hydroxy and / or sulfo derivatives are used for this of these connections recommended.
• additives these substances are collectively referred to as additives.
• the additives are generally available in the form of powders.
• the introduction of such powdery additives in processes for the production of cellulose from lignocellulose materials and their bleaching is problematic. If you add the powdered additives to the lignocellulosic material to be used, it is to be expected here that the finer proportions of the additives will get into the environment in the form of a dust, thus being partially withdrawn from the intended use, which bothers people working near the addition point and the risk of Can cause dust explosions.
• even distribution is difficult.
• an even distribution of the additives is desirable in order to achieve a uniform pulp quality.
• a uniform distribution of the additives is also made more difficult by the fact that the additives are generally only very slightly soluble in water and in the aqueous electrolyte solutions used in pulp production (e.g. only 6-10 dissolve in 1 liter of water at 50 ° C - 4 g of 9,10-anthraquinone).
• the additives of water and aqueous electrolyte solutions are so poorly wetted that the finer fractions of the powdered additives cannot be stirred in or can only be stirred in with difficulty, but rather float on the surface without being wetted, if appropriate with the inclusion of air.
• the additives have a relatively high specific density (e.g. anthraquinone has a specific density of 1.438 g / cm 3 at 20 ° C.), so that the coarser proportions of the powdery additives which can be stirred into water or electrolyte solution can be put it back down quickly and after standing briefly on the bottom of the vessel form a compact layer that can only be swirled up with difficulty.
• the addition of the additives directly to the cooking liquor, in the mixture of lignocellulose material and cooking liquor or in the form of a slurry in water or dilute electrolyte solutions is also not a way to ensure that the additives are evenly distributed.
• a dispersion has now been found for use in pulp production, which is characterized in that it contains organic, cyclic, keto and / or hydroxyl group-containing compounds and a liquid dispersant of the same or similar specific density as the organic, cyclic, keto and / or contains compounds containing hydroxyl groups.
• pulp production is understood to mean all processes and process steps in which lignin in materials containing lignin and cellulose is acted on chemically. Examples of this are alkaline, neutral and acidic pulping processes for lignocellulose materials, such as wood, straw, bagasse and grasses, and bleaching processes for partially or largely digested lignocellulose materials.
• the dispersed substances e.g. B. monocyclic, dicyclic and / or polycyclic compounds.
• the keto and / or hydroxyl groups, in particular 9,10-anthraquinone can be present in a wide variety of grain sizes.
• the dispersed substances, in particular 9,10-anthraquinone can consist of at least 80% by weight of particles with particle sizes in the range from 1 ⁇ m to 5 mm.
• the dispersed substances, in particular anthraquinone can also have particle sizes in the range from approximately 50 to 500 ⁇ m with the greatest frequency of the particles in the range from approximately 200 to 300 ⁇ m.
• the grain size distribution has no particular influence.
• the grain size distribution can be relatively narrow around an average value, but it can also extend over the entire aforementioned ranges and beyond.
• 910-anthraquinone this has the advantage that anthraquinone can be introduced into the dispersion according to the invention, as is generally obtained in industrial production.
• Liquids which have the same or a similar specific density as the dispersed substance or the dispersed substances are suitable as dispersants for the dispersion according to the invention.
• Liquids are understood here as pure liquid substances, solutions and dispersions.
• the dispersant can be, for example, an aqueous solution of electrolytes which has a specific density in the range from 1.2 to 1.6 g / cm 3 .
• the specific density of the dispersing agent is preferably 1.35 to 1.5 g / cm 3 , particularly preferably 1.4 to 1.45 g / cm 3 .
• the aqueous solution of electrolytes can be, for example, a solution of hydroxides and / or salts of the metals of the first and / or second main group of the periodic table and / or a solution of nitrogen bases and / or salts of nitrogen bases or a solution of acids.
• the first and second main groups of the periodic table are the groups referred to as groups la and ila, see for example the last pages of Cotton & Wilkinson, "Advanced Inorganic Chemistry", 2nd edition.
• the aqueous solution is preferably a solution of hydroxides, sulfides, sulfites, bisulfites, sulfates, thiosulfates and / or carbonates of sodium, potassium, calcium and / or magnesium.
• suitable nitrogen bases are alkylamines, hydroxyalkylamines or alkylene amines, such as ethylenediamine, propylamine and / or ethanolamine, and salts of nitrogen bases, for example ammonium salts, such as acid addition salts or quaternary salts.
• suitable nitrogen bases are alkylamines, hydroxyalkylamines or alkylene amines, such as ethylenediamine, propylamine and / or ethanolamine, and salts of nitrogen bases, for example ammonium salts, such as acid addition salts or quaternary salts.
• acids are sulfuric acid, phosphoric acid and nitric acid.
• the aqueous solution is particularly preferably a solution of sodium hydroxide, sodium sulfide, sodium sulfite, sodium bisulfite, sodium sulfate, sodium thiosulfate, sodium carbonate, potassium sulfide, magnesium bisulfite, calcium bisulfite and / or ammonium sulfite or sulfuric acid.
• the aqueous solution is particularly preferably a solution of sodium hydroxide, sodium bisulfite and / or sodium thiosulfate. It is not necessary to limit yourself to a single one of the specified electrolytes. Rather, solutions or suspensions of mixtures of the listed electrolytes can also be used.
• electrolytic solutions which are taken from different places in the pulping plants, after concentration, e.g. B. by evaporation of water, or after the addition of further amounts of electrolytes as dispersants.
• concentration e.g. B. by evaporation of water
• electrolytes as dispersants.
• white liquors, cooking liquors, black liquors, thick running and / or green liquors can be used as the dispersing agent, if appropriate after adjusting the density by evaporating water or adding further amounts of electrolyte.
• Black liquors are the used cooking liquors separated from the pulp after the lignocellulose material has been digested. These contain, as organic constituents, the solubilized accompanying substances of cellulose, for example lignin sulphonates and / or alkali lignins, optionally also hemicelluloses and low molecular weight conversion products of the constituents of the lignocellulosic material, as inorganic constituents, for example mainly alkali metal sulphate and alkali metal carbonate, as well as alkali metal alkali metal compounds and alkali metal alkali metal compounds, as well as alkali metal organic compounds usually also free alkali metal base, alkali sulfide, alkali sulfite and alkali thiosulfate.
• the specific density of the black liquors can be, for example, 1.05 to 1.40 g / cm 3 depending on the concentration of the dissolved substances.
• the solids content can range, for example, from 10 to 70% by
• Thick liquors are those black liquors that are highly viscous at room temperature due to their high solids content of, for example, more than 50% by weight. Depending on the digestion process, thick liquors can be obtained directly by separating cellulose or by evaporating black liquors with a low solids content.
• Green liquors are solutions which contain, for example, 5 to 20% by weight of alkali metal carbonate and, for example, 1 to 5% by weight of alkali metal sulfide, which are prepared from water and the molten salt which is obtained when the organic constituents of the thick liquors are burnt. Green liquors usually also contain sodium sulfate, sodium sulfite, sodium thiosulfate and sulfur. Green liquor, for example, has a specific density in the range from 1.1 to 1.30 g / cm 3 .
• White liquors contain, for example, 80 to 200 g of alkali metal base, 10 to 80 g of alkali metal isulfide and 20 to 50 g of alkali metal carbonate per liter of solution. They usually also contain alkali metal sulfite, alkali metal sulfate and alkali metal thiosulfate, optionally also sulfur. Their solids content is, for example, about 10 to 35% by weight.
• the specific density of the white liquors is, for example, between 1.1 and 1.3 g / cm 3.
• the concentration of dispersed substances according to the invention can be set as desired within wide limits. There are practical limits for a high content of dispersed substances due to the requirement for pumpability, for a low content of dispersed substances due to the high use of electrolytes in relation to the dispersed substance.
• the dispersion according to the invention can have, for example, a content of dispersed substances of 5 to 70% by weight, preferably 30 to 60% by weight.
• a special embodiment of the dispersion according to the invention is characterized in that it additionally contains wetting agents.
• Suitable wetting agents are cationic, anionic or nonionic wetting agents, preferably those which are obtained as by-products in the processes for cellulose production. Examples of this are black liquor, thick liquor and / or the lignin sulfonates or alkali metal lignins obtainable therefrom.
• wetting agents can be added in amounts of, for example, 0.01 to 20 percent, preferably 0.05 to 10 percent.
• Wetting agents can be added, for example, in such a way that powdered wetting agent is added to the pulverulent substance to be dispersed before the dispersion is prepared.
• the wetting agent can also be added to the liquid dispersant in liquid or solid form.
• dispersions according to the invention is characterized in that they additionally contain viscosity-increasing substances.
• Water-soluble polymeric compounds such as polyvinyl alcohol and / or methyl cellulose, for example, are suitable as viscosity-increasing substances.
• Thick liquor can also be used, ie black liquor, for example, concentrated to 50 to 70% solids. Pure thick liquor, for example with a solids content of 64%, which is a highly viscous mass at 20 ° C., forms a stable dispersion with anthraquinone, for example at 80 ° C. despite a specific density of only 1.25 g / cm 3 .
• the favorable viscosity-increasing effect of the thick liquor also has an effect on mixtures of 60 parts thick liquor and 40 parts water or on mixtures of 50 parts thick liquor and 50 parts white liquor.
• Inorganic substances such as polysilicates, for example pyrogenic silica with a specific surface area of approximately 380 m 2 / g, can also be used as the viscosity-increasing substances.
• the use of inorganic, viscosity-increasing step is usually not particularly advantageous, since these are not removed by combustion and can accumulate in the pulping process. Be particularly preferred therefore used as the viscosity-increasing substances polyvinyl alcohol and methyl cellulose.
• thick liquor or mixtures containing thick liquor with water or electrolyte solutions is also favorable.
• Polyvinyl alcohol and / or methyl cellulose can be contained in the dispersing agent, for example in amounts of 5 to 20% by weight, and thick liquor in amounts of, for example, 50 to 100% by weight.
• the dispersion according to the invention which contains viscosity-increasing substances, has the advantage that this dispersion is also stable if the specific density of the dispersing agent differs markedly from the specific density of the dispersed substance.
• a relatively low-concentration electrolyte solution as a dispersing agent in the presence of viscosity-increasing substances.
• dispersions containing 9,10-anthraquinone specific density of anthraquinone at 20 ° 1,438 g / cm 3
• the dispersant has a specific density of about 1.25 g / cm 3 .
• carrier dispersion is understood here and below to mean a dispersant which is present as a dispersion even before the addition of the organic, cyclic, keto and / or hydroxyl-containing compounds.
• carrier dispersions can e.g. B. can be obtained if thick liquor or black liquor is brought together with concentrated aqueous electrolyte solutions of the type described above or with solid electrolytes of the type described above, in particular sodium hydroxide solution or caustic soda.
• carrier dispersions has the particular advantage that a dispersion which is easy to handle at room temperature is obtained using process waste with a reduced amount of electrolytes.
• the temperature is not a decisive variable in the production, storage and application of the dispersion according to the invention and can be chosen as desired within wide limits.
• the practical lower value is the ambient temperature
• the upper practical value is the temperature at which significant amounts of water evaporate under normal pressure, shifting the specific density of the dispersant.
• thick liquor as a wetting agent, as a viscosity-increasing substance and / or as a component to form a carrier dispersion, a working temperature in the range of 50 to 90 ° C is recommended, since thick liquor solidifies upon contact with cold water or cold electrolyte solution and only gradually dissolves or disperses becomes.
• the dispersion of the invention can be prepared in various ways.
• the substance to be dispersed can be stirred into the prepared dispersant. If the dispersant is composed of two or more parts, the order of addition is freely selectable.
• the substance to be dispersed can be stirred into the prefabricated, optionally containing a wetting agent and / or a viscosity-increasing substance and / or a carrier suspension.
• the substance to be dispersed can also be stirred into the aqueous electrolyte solution of the same or similar density and subsequently mixed with a wetting agent and / or a viscosity-increasing substance.
• the substance to be dispersed can be mixed with the solid electrolyte, for example with solid sodium hydroxide, optionally together with a wetting agent, and water can be added to this mixture or this mixture can be added to water.
• a particularly preferred dispersion in the context of the dispersions according to the invention is characterized in that it contains 30 to 60% by weight of 9,10-anthraquinone, which has at least 80% a grain size in the range from 50 to 500 ⁇ m and 40 to 70% by weight.
• a very particularly preferred dispersion within the scope of the dispersion according to the invention has the above characteristics, the aqueous solution containing sodium hydroxide, sodium bisulfite and / or sodium thiosulfate.
• the dispersion according to the invention in particular dispersion containing anthraquinone, is used in processes for the production of cellulose.
• the dispersion according to the invention can be fed into the pulp before the boiling, but advantageously before the impregnation, in which the lignocellulose material is soaked at a temperature of 80 to 100 ° C. with the aqueous solution of the digestion chemicals.
• the aqueous solution of the digestion chemicals also serves as a conveying medium for loading impregnators and / or cookers with lignocellulose mate rial.
• the dispersion according to the invention in particular a dispersion containing anthraquinone, can be metered into the returning solution or into the solution loaded with wood chips, if appropriate also directly into the impregnator or cooker.
• the anthraquinone generally goes into solution and can thus penetrate the wood chips in a molecular distribution during the impregnation process. As a result, pulps of uniform quality are obtained.
• the amount and composition of the dispersion of the invention when used in pulp production can be such that the digestion solution z. B. 0.01 to 1.0 wt .-% of the amount of chemicals required for digestion is added in the form of the dispersion according to the invention. In a process for pulp production with, for example, 99% recycling of the pulping chemicals, this corresponds to the 0.01 to 1.0 times the amount of pulping chemicals which must be added fresh to compensate for losses.
• the dispersion according to the invention in particular a dispersion containing anthraquinone, has a number of advantages.
• the preparation of these dispersions is simple and can be done without special equipment.
• the dispersion of the invention is pumpable, i. that is, it can be metered with the aid of a pump suitable for pumping dispersions, for example a peristaltic pump, an eccentric screw pump or a piston pump and conveyed through pipelines.
• the dispersion of the invention is stable for a long time. It can be stored for at least a few days, generally one or more weeks, with the dispersed substances not settling or floating so little or that they can float by simple means, e.g. B. a slow running stirrer, can be brought back into the dispersed state. This has the advantage that a larger amount of the dispersion can be produced at once, the metering then z. B. can be done by a simple volume or quantity measurement.
• the dispersion according to the invention can be produced locally separately from the cellulose production, for example at the anthraquinone manufacturer. In this case, the finished dispersion can be made available to the pulp manufacturer.
• the production of the dispersion according to the invention can, however, also take place at the pulp manufacturer, since, for example, with the exception of the substance to be dispersed, only those substances can be used which can be used in the pulp production anyway and / or are obtained in the process. In this case, only the pure active ingredient, e.g. B. anthraquinone to be transported.
• the dosage of the dispersion according to the invention is particularly simple. Given the delivery capacity of a metering pump, the metering of the dispersed substance into the pulping plant can be changed by setting higher contents of dispersed substance by adding powdered substance to be dispersed and lower contents of dispersed substance by adding dispersing agent.
• the dispersion according to the invention can thus be adapted and changed to the operating conditions of the cellulose production without changing the performance of the metering pump.
• the beneficial effects of the presence of organic, cyclic, keto and / or hydroxyl-containing substances can be optimally used without any disadvantages.
• the organic constituents of the dispersion according to the invention are also incinerated when the process waste water is incinerated.
• the inorganic constituents of the dispersion according to the invention in particular the aqueous electrolyte solutions, can be selected in such a way that no foreign substances enter the respective pulping process.
• the inorganic components can be adapted to various pulping processes. There can then be no accumulation of non-process substances, which is of particular importance in modern cellulose production processes in which the pulping chemicals are circulated.
• the dispersion according to the invention completely meets the requirements for use in the production of cellulose, including cellulose bleaching. This is because stable dispersions are usually only obtained when the dispersed particles have a grain size on the order of colloidal particles. In the case of coarser dispersions, the dispersed particles usually settle sooner or later (see Römpp, Chemielexikon, 6th edition, page 6286 [1966]). Colloidal particles can only be obtained in complex milling processes. Such grinding processes are not necessary in the production of the dispersion according to the invention.
• dispersion according to the invention can be prepared with dispersants which allow adaptation to the particular pulping process, since the dispersants can be selected from a large number.
• a dispersion according to the invention can thus be made available practically for any conventional pulping process, in which no extraneous process materials have to be introduced.
• a process for the production of pulp from lignocellulose materials in the presence of organic, cyclic, keto and / or hydroxyl-containing compounds was also found, which is characterized in that the organic, cyclic, keto and / or hydroxyl-containing compounds were in the form of one of the dispersions previously described starts.
• this process can be carried out in a manner known per se.
• this process can be carried out by digesting lignocellulosic materials in a sulfite solution, which can be acidic, neutral or alkaline, and adding the dispersion according to the invention to the digesting solution before or after adding the lignocellulosic material.
• the dispersion according to the invention can also be used in the known cellulose production processes which are referred to as the Kraft process, the soda process and the polysulfide process.
• the dispersion according to the invention can also be used in the known oxygen-alkali process for pulping and / or in the bleaching processes known for pulping.
• the dispersion according to the invention can be used, for example, in such an amount that 0.01 to 1.0% by weight of the amount of chemicals required in the respective process are used in the form of a dispersion according to the invention.
• 9,10-Anthraquinone in the form of one of the dispersions according to the invention is preferably used in the process according to the invention.
• the use of the dispersion designated as particularly preferred in the context of the dispersions according to the invention is particularly preferred.
• the method according to the invention has a number of advantages. For example, the metering and uniform distribution of organic, cyclic, keto and / or hydroxyl-containing compounds is possible without difficulty, and as a result, pulps of uniform quality are obtained. It is also possible to realize the positive effects of the addition of organic, cyclic, keto and / or hydroxyl-containing compounds found under ideal conditions on a laboratory scale in large-scale pulping plants.
• an anthraquinone was used in the examples, as is the case in a technical production process. 80% by weight of this anthraquinone has a grain size in the range from 100 to 500 ⁇ m.
• 50 g of 9,10-anthraquinone are introduced with stirring into 50 g of a 41% aqueous sodium hydroxide solution (specific density 1.44 g / cm 3 ).
• the anthraquinone is wetted well, and a thick, pumpable dispersion is obtained, the solid content of which floats up over the course of a few days due to trapped air bubbles.
• a homogeneous distribution is achieved by slowly stirring the dispersion.
• the specific density of the mixture of white liquor and caustic soda is 1.44 g / cm 3 at 20 ° C. Relatively little caustic soda is required for the stable, thin, liquid dispersion that turns reddish over the course of a few hours. (25% more caustic soda is required for the dispersion described in Example 8.)
• 40 g of 9,10-anthraquinone are mixed at 80 ° C. with 48 g of thick liquor with a specific density of 1.25 g / cm 3 at 80 ° C. and a solids content of 64% by weight and 12 g of saturated soda solution.
• the specific density of the dispersant is 1.34 g / cm 3 at 20 ° C.
• the dispersion has little tendency to let the solid settle. This can be avoided by slowly stirring the dispersion.
• a carrier dispersion which was prepared from 32.5 g of black liquor, corresponding to the black liquor used in Example 2, and 17.5 g of caustic soda and a specific density of 1.39 g at 20 ° C. / cm 3 .
• the dispersion obtained is pumpable and does not settle.
• the easily manageable dispersion which is produced from 40 g of 9,10-anthraquinone and 60 g of 60% phosphoric acid (specific density 1.43 g / cm 3 ), remains stable as a dispersion for at least 2 weeks.

Landscapes

• Paper (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6037102

Family Applications (1)

Country Status (17)

Families Citing this family (4)

Family Cites Families (5)

• 1978
  • 1978-04-15 DE DE19782816473 patent/DE2816473A1/de not_active Withdrawn
• 1979
  • 1979-03-16 IN IN177/DEL/79A patent/IN150690B/en unknown
  • 1979-04-05 PH PH22355A patent/PH14724A/en unknown
  • 1979-04-05 NO NO791151A patent/NO791151L/no unknown
  • 1979-04-09 EP EP79101084A patent/EP0004928B1/de not_active Expired
  • 1979-04-09 DE DE7979101084T patent/DE2960241D1/de not_active Expired
  • 1979-04-10 ES ES479476A patent/ES479476A1/es not_active Expired
  • 1979-04-11 BR BR7902259A patent/BR7902259A/pt unknown
  • 1979-04-11 AR AR276157A patent/AR220189A1/es active
  • 1979-04-11 PT PT69477A patent/PT69477A/pt unknown
  • 1979-04-12 FI FI791211A patent/FI64668C/fi not_active IP Right Cessation
  • 1979-04-12 CA CA000325807A patent/CA1136808A/en not_active Expired
  • 1979-04-12 ZA ZA791770A patent/ZA791770B/xx unknown
  • 1979-04-12 NZ NZ190182A patent/NZ190182A/xx unknown
  • 1979-04-13 JP JP4446379A patent/JPS54138603A/ja active Pending
  • 1979-04-13 TR TR20509A patent/TR20509A/xx unknown
  • 1979-04-13 AT AT0280179A patent/AT372716B/de not_active IP Right Cessation
  • 1979-04-17 AU AU46076/79A patent/AU4607679A/en not_active Abandoned

Also Published As

Similar Documents

Legal Events