1554results about "Pulping with inorganic bases" patented technology

A lyocell nonwoven fabric having fibers characterized by pebbled surfaces and variable cross sections and diameters along the fibers and from fiber to fiber, is disclosed. The lyocell nonwoven fabric is produced by centrifugal spinning, melt blowing or spunbonding. The lyocell nonwoven fabric has fibers that can be made in the microdenier range with average weights as low as one denier or less. The lyocell nonwoven fabric has fibers with low gloss, a reduced tendency to fibrillate and have enhanced dye receptivity.

An omnibus process of pulping and bleaching lignocellulosic materials in which a charge of a lignocellulosic material is biopulped and/or water extracted prior to pulping and bleaching. The lignocellulosic material may be mechanically pulped and bleached in the presence of an enzyme that breaks lignin-carbohydrate complexes. The aqueous extract in embodiments including a water extract step is separated into acetic acid and hemicellulose sugar aqueous solutions.

Cellulose containing dope is extruded through orifices and into a stream of gas moving in a direction generally parallel to the direction that the filaments are formed with varying degrees of mechanical attenuation provided to the filaments using a take-up device, such as a winder.

The present invention comprises an improved method for refining cellulose that produces a highly refined cellulosic material in combination with a hydrocolloid. The method comprises soaking raw material from primarily parenchymal cell wall structures in an aqueous solution which need not contain an agent to modify the fiber (e.g., a mild alkalizing or alkaline agent and/or solution) using reduced temperatures and pressures, and refining the material with a plate refiner so that a waste water stream is reduced in volume. The mass is dried to produce the HRC fiber. The HRC fiber displays a water retention capacity of about 25 to at least about 56 g H₂O/g dry HRC and retains moisture under conditions that are ordinarily used to remove moisture from materials. The highly refined fiber product can also provide excellent thickening properties and can be used in a wide variety of materials, including edible materials.

A process for making lyocell fibers including the steps of pulping raw material in a digester to provide an alkaline pulp, wherein the raw material includes sawdust in an amount greater than 0% up to 100%; contacting the alkaline pulp including cellulose and at least about 7% hemicellulose under alkaline conditions with an amount of an oxidant sufficient to reduce the average degree of polymerization of the cellulose to the range of from about 200 to about 1100 without substantially reducing the hemicellulose content or substantially increasing the copper number of the pulp; and forming fibers from the pulp.

Basic magnesium carbonate comprising a tubular aggregated particle of flaky fine crystals.

The present invention provides compositions, useful for making lyocell fibers, having a high hemicellulose content, a low copper number and including cellulose that has a low average degree of polymerization (D.P.) and a narrow molecular weight distribution. Further, the present invention provides processes for making compositions, useful for making lyocell fibers, by contacting an alkaline pulp having a high hemicellulose content of at least about 7% with an oxidant sufficient to reduce the average degree of polymerization to about 200 to 1100 without substantially reducing the hemicellulose content or increasing the copper number of the pulp.

The production process of bamboo fibre viscose pulp includes the following main steps: pre-alkalizing, secondary cooking, plate (belt) type washing and bleaching, and is characterized by mixing insoluble bamboo pulp undergo the process of modification treatment to produce soluble viscose bamboo pulp. As compared with cotton pulp production process it can reduce discharge of waste water by 35%, and is approaching to or superior to cotton pulp in quality.

A method for fractionating fibrous biomass comprising cellulose, hemicellulose and lignin components to separate said lignin, cellulose and hemicellulose from one another comprises: (a) shredding said fibrous biomass; (b) concurrently with or subsequent to said shredding, contacting said biomass with an aqueous solution of a nitrate ion source at a concentration of about 0.1-0.3% at a temperature in the range of about 60° to about 80° C. to initiate nitration of the lignin component of said biomass; (c) submerging said partially nitrated biomass in an aqueous solution of a nitrate ion source in the presence of an aluminum compound at a temperature within the range of about 75-100° C. for a time sufficient to complete the nitration of said lignin component; (d) contacting the nitrated biomass produced in step (c) with an alkaline extraction liquor comprising NH4OH at an initial concentration sufficient to solubilize said nitrated lignin component and said hemicellulose component from said cellulose component of said biomass; e) recovering said cellulose from said extraction liquor containing said solubilized nitrated lignin and hemicellulose components, wherein said cellulose comprises at least about 88% alpha cellulose; (f) treating said extraction liquor with an acid to precipitate lignin contained therein, and (g) separating said lignin from soluble hemicellulose in said extraction liquor. The recovered cellulose component comprises at least 88% alpha cellulose and is useful as a starting material for the production of ethanol.

The present invention discloses methods of bleaching chemical pulp that combine xylanase enzymes with hydrogen peroxide, peracids, or a mixture. The method comprises the steps of carrying out a chemical pulping operation, optionally followed by delignifying the pulp with oxygen, then combining xylanase enzymes with hydrogen peroxide, peracids, or a mixture to bleach the pulp. The method allows the mill to use both xylanase and peracids in a single bleaching tower to decrease the usage of chlorine dioxide and other bleaching chemicals. The pulp bleaching method of the present invention may be performed in a pulp mill as part of a complex pulp bleaching process.

The invention relates to an oxygen delignification processing method of grass unbleached chemical pulp. The oxygen delignification of the pulp is processed after cooking and before bleaching. Its rigidity before the oxygen delignification is potassium permanganate value 16-28 (equals to karber value 26-50). After pumping into the oxygen delignification reaction tower and inflating sodium hydroxide, magnesium salt and oxygen, the chemical pulp happen the oxygen delignification in the reaction tower. The chemical pulp with rigidity of potassium permanganate value 10-14 (equals to karber value 14-18) is achieved after the oxygen delignification. The invention can remove the lignin in the pulp effectively and the removal rate is 86-98%. It reduces the degradation of the cellulose to simplify the bleaching process and cut down the dosage of the chemicals. The bleached pulp has good rigidity and drainability. The breaking length of the pulp can reach 4500-8000m and its fold-resistant times can reach 20-70.

The invention provides for methods for producing pulp (comprising cellulose) and lignin from lignocellulosic material, such as wood chips. The methods involve acid catalyzed hydrolysis. Lignocellulosic material having a relatively high moisture concentration can be used as the starting material. The lignocellulosic material is impregnated with an acid (preferably nitric acid) and heated. During the heating lignin is depolymerized at relatively low temperatures, and the acid catalyst is distilled off. The acid catalyst can be collected and recycled after impregnation and heating. The lignocellulosic material is then digested in an alkaline solution under heat, dissolving the lignin and allowing the pulp to be removed. Acid is added to the black liquor to precipitate the lignin which is then removed. The resultant amber liquor can be further processed into other ancillary products such as alcohols and/or unicellular proteins.

According to one embodiment of the invention, a system for processing biomass includes a water-impermeable bottom liner, a gravel layer supported by the bottom liner, a drain pipe disposed within the gravel layer, a biomass input device operable to deliver biomass over the gravel layer to form a biomass pile, a lime input device operable to deliver lime to the biomass for pretreating the biomass, a distribution pipe elevated above the gravel layer, and a pump operable to circulate water through the biomass pile by delivering water to the distribution pipe and receiving water from the drain pipe after it has traveled through the biomass pile.

According to another embodiment, a method for biomass pretreatment with alkali, conducted at ambient pressure for approximately 4-16 weeks at temperatures ranging from approximately 25° C. to 95° C. Biomass may be lignocellulosic biomass and may be rendered suitable for enzymatic digestion or pulp production.

A high pH and a low pH process for reducing the degree of polymerization of a pulp having a hemicellulose content of at least 7%. The high pH is greater than 8, and the low pH process is 2 to 8. The high pH process reduces the degree of polymerization without substantially increasing the copper number. The low pH process requires a subsequent treatment with alkali to reduce the copper number of the pulp to less than 2. The process can be practiced in pulp mills with a bleaching sequence having one or more E or D stages. At the end of the bleach sequence, a pulp having a degree of polymerization of 200 to 1100, a copper number of less than 2, and a hemicellulose content of at least 7% is provided. The pulp can be used to make lyocell fibers.

A process of treating a lignocellulosic material includes a pre-extraction step in which hemicellulose is extracted from the lignocellulosic material. Then, in a solvent pulping step, the lignocellulosic material is separated into pulp by contacting the lignocellulosic material with a cooking liquor comprising a solvent. In one embodiment, the solvent has a boiling point of at least about 150° C. In another embodiment, the cooking liquor comprises a mixture of solvent and water.

The present invention relates to a process for the production of xylose and dissolving pulp from xylan-containing biomass, such as hardwood. The invention is based on prehydrolysis of the xylan-containing biomass with SO₂ in specified conditions, followed by chromatographic fractionation, nanofiltration or precipitation crystallization of the xylose-containing prehydrolyzate to obtain a xylose product having a xylose content of at least 55% on DS. The dissolving pulp obtained from the process can be used for example for the production of viscose.

The present disclosure relates to producing paper or paperboard having improved stiffness and strength, compared to the conventional paperboard at the same basis weight. It also discloses a method of wood pulping having a significantly increased yield and providing fiber pulps with enhanced properties such as strength and stiffness. Wood chips are chemically pulped to a high kappa number, providing a rejects component and an accepts component. The rejects component is subjected to a substantially mechanical pulping process, optionally in a presence of bleaching agent, prior to blending back into the accepts component. The resulting fiber blend is washed, optionally bleached, and subjected to a papermaking process to provide paper or paperboard with enhanced strength and stiffness at low basis weight.

The present invention serves for loading a pulp suspension (S) with calcium carbonate. Liquid calcium hydroxide as milk of lime (7) is added during or before the pulp operation (1) carried out to form the pulp. By introducing gaseous carbon dioxide (8) into the pulp suspension thus treated, a chemical reaction is triggered therein, in which the finely divided calcium carbonate is precipitated. The present invention is particularly economic and effective due to the early addition of calcium oxide or calcium hydroxide.