229 results about "Pulp bleaching" patented technology

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 the technical field of papermaking raw material processing, in particular to a process for preparing recovered pulp with high whiteness and high cleanliness in a papermaking industry. The process comprises the following steps of: selecting and feeding of waste paper raw materials; disintegration; screening purification; first flotation deinking; first concentrated heat dispersion; second flotation deinking; second concentrated heat dispersion; oxidation bleaching; reduction bleaching; and storage in a storage tower. According to the process, 20-30 percent of high-quality office waste paper and 70-80 percent of other low-quality waste paper raw materials are matched, so that the cost of the waste paper raw materials is effectively reduced, and the corporate profit is increased. An advanced rotary drum pulper, a pulping machine and a production line of office waste paper screening purification, flotation deinking, concentrated heat dispersion and pulp bleaching are introduced, and the recovered pulp is prepared through the efficient use of chemicals and an effective production control process. The whiteness of the recovered secondary pulp achieves 90 percent ISO, and the cleanliness is high. The whiteness and the cleanliness of finished culture paper are increased.

The present invention aims to further advance the acid treatment or irradiation technology for pulp to develop a bleaching process using smaller amounts of chlorine chemicals with higher efficiency as compared with conventional bleaching processes. It also aims to provide an excellent high brightness pulp having a low environmental impact and no discoloration as well as a paper containing it. The present invention provides a chlorine-free bleaching process with very high efficiency by irradiating a pulp washed after an acid treatment with UV light and/or visible light at a wavelength of 100-400 nm under alkaline conditions, preferably in a pH range of 10-13. The acid treatment can be performed under conditions of pH 1-6 and a temperature of 80° C. or more. The irradiation treatment can be performed in the presence of at least one compound selected from the group consisting of reducing agents, peroxides, and hydrogen-donating organic compounds. The present invention also provides a high brightness chemical pulp having an ISO brightness of 88% or more and a brightness loss of 1.0% or less in a specific fading test.

The invention provides a method for removing fluorescent substances in waste paper pulp, which relates to improvement of the waste paper pulping bleaching technology and more specifically to bleaching treatment on waste paper pulp using a chemical approach. The method can remove fluorescent substances in waste paper pulp. According to the invention, the processes of bleaching and fluorescence removal are carried out simultaneously; chlorine dioxide is used as a fluorescence remover to destroy luminophores and molecular structures of fluorescence, which not only radically eradicates fluorescence, but also eliminates influence of fluorescent substances on human health; chlorine dioxide also has an effect of bleaching, which compensates for and gets rid of the defect of decreased whiteness of paper pulp after removal of fluorescence; the method is in combined use with the waste paper bleaching technology to partially substitute conventional bleaching technology, which not only is easy to realize, but also saves investment and considerable energy and chemicals, producing the two effects of bleaching and fluorescence removal through a single technology.

The invention discloses an improved pulp bleaching technique for reed pulp paper-making, which comprises: first, using deoxylignin for bleaching, wherein, slurry concentration 8-20%, temperature 85-130Deg, oxygen consumption quanity 1-4.5Kg per ton slurry, NaOH consumption quanity 1-4Kg per ton slurry, and MgSO4 consumption quantiy 0.1-1.0%; second, using biological enzyme for bleaching, wherien, enzyme adding quanity 20-80g per ton slurry, temperature 30-80Deg, slurry concentration 5-16%, pH value 5-12, slurry hardness 2-8(KMnO4), and time 0.5-4h; third, adding hypochlorite for bleaching. This invention can reduce bleachability and back-yellow value, improves yield and slurry hardness, and decreases pollution to environment.

The invention discloses a bleaching process with low pollution used for straw pulp by virtue of elemental chlorine-free bleaching agents such as oxygen, chlorine dioxide, hydrogen peroxide and the like. The invention is characterized in that the process comprises the steps as follows: (1) on oxygen delignification section, sealing, sifting and washing are carried out; (2) on chlorine dioxide delignification section, washing is carried out; (3) on alkaline extraction section, washing is carried out; (4) on chlorine dioxide whitening section, washing and papermaking are carried out. The process of the invention is simple and feasible, applicable for reed pulps and the mixed pulp thereof and anaphalis yedoensis, the final brightness of the pulp of the reed pulps (ISO) reaches 78-85%, the brightness stability and the strength are good, and tear index is more than or equal to 8.0mN.m<2>/g; as no elemental chlorine joins the bleaching process, the generation amount of organic chloride during the bleaching process is greatly lowered and the pollution to ecological environment is reduced, thus having obvious social and economic benefits.

A novel totally chlorine-free bamboo-pulp bleaching process is provided. The invention relates to a novel totally chlorine free (TCF) bamboo-pulp bleaching process, is a new bionic bleaching technology for paper pulp. The invention essentially comprises the following procedures: (1) Synthesizing enzyme-imitated metal salen, using Schiff base salen to react with metallic organic acid salt to synthesize metal salen; (2) Pre-treatment bleaching bamboo pulp, carrying out bleaching pre-treatment on the oxygen delignification sulfate bamboo pulp with metal salen, NaOH, H2O2 and O2 existing; (3) Subsequent TCF bleaching, carrying out three bleaching treatments, namely, alkaline treating enhanced by hydrogen peroxide, bleaching by peroxy acid and bleaching by hydrogen peroxide the bamboo pulp pre-treated by enzyme-imitated metal salen. For the invention, the source is wide, the metal salen is easy to synthesize, the yield rate is high, the cost is low, the consumption is very low; the metal salen is easy to store, has no demanding requirement on the environment, can obviously improve the whiteness of paper pulp, reduce the load of waste water pollution in bleaching, and saves the use of bleaching chemicals.

An apparatus for carboxylating wood pulp which utilizes the wood pulp bleach plant and the method of carboxylating the pulp which takes place in the bleach plant.

Th einvention discloses high water resistance straw lining paper and a preparation method thereof. The preparation method comprises the following steps: (1) mixing and pulping bleaching injection andhardwood pulp, adding filler, a wet strength agent, a sizing agent, retention aid and the like, and preparing fiber pulp which can be put on a net through slag removing and concentration regulating; (2) forming and squeezing the fiber pulp with a fourdrinier machine, controlling the curve of a dryer to completely cure the sizing agent, performing a surface sizing process with a three-element surface sizing agent of starch with alkyl ketene dimer and carboxymethylcellulose; and preparing the high water resistance straw lining paper through drying, press polishing and rolling. The straw lining paper has good water resistance and wet strength and can be used for effectively prevent liquid infiltration, and each index can accord with the safety standard of national food package materials.

An apparatus for carboxylating wood pulp which utilizes the wood pulp bleach plant and the method of carboxylating the pulp which takes place in the bleach plant.

A process for bleaching paper pulp includes such steps as adding hypochlorite, prebleaching at 30-60 deg.C for 30-150 min, water washing, adding ClO2, bleaching and water washing. Its advantages are low pollution and low consumption of water.

Based on photochemical principle, plant fiber pulp after being pre-treated is irradiated with light, and in alkali environment and under the aid of introduced oxygen or air and photobleaching catalyst, the residual lignin in pulp is degraded via photochemical reaction into leached out fragments and thus eliminated, resulting in high whiteness pulp. During the bleaching process, different shielding agent may be added to shield partial light selectively to protect the physical strength of pulp. The bleaching process is environment friendly, and has less corrosion to the apparatus and simple operation.

The invention provides genes, an expression vector, a production bacterial strain and application of xylanase with high temperature resistance, strong base resistance, high efficiency and stability in pulp bleaching. The genes of the xylanase provided in the invention realize high expression in Pichia pastoris by utilizing a codon optimizing and multi-copy technique; the expressed xylanase has no cellulase activity, high temperature resistance and high base resistance; and the xylanase can be applied to wheat straw pulp bleaching; when applied to an elemental chlorine free (ECF) bleaching procedure, the xylanase saves chlorine dioxide by 10%; when applied to a hydrogen peroxide (OP) bleaching procedure, the xylanase saves hydrogen peroxide by 10%.

A method for bleaching cellulosic pulp is disclosed, with one embodiment revealing a three-step bleaching method for cellulosic pulp comprising an activating bleach step, an alkaline peroxide step, and a reductive bleach step. The cellulosic pulp treated according to the present invention may possess a greater GE brightness gain than if treated according to conventional methods, while not suffering a significant loss of lignin. The cellulosic pulp may comprise recycled fibers, including those with high groundwood content. The bleaching method may also decrease the pH of the pulp.

The invention relates to Trametes Versicolor YS-L613 and a breeding method and application thereof. The Trametes Versicolor YS-L613 is prepared by the method through mutation breeding. The breeding method is to take Trametes Versicolor as a starting strain, adopt composite mutation breeding technology which combines UV, 60 CO, ultraviolet rays, nitrosoguanidine, ion implantation and microwave treatment, and breed the YS-L613 strain for high-yield production of laccase. The invention performs breeding operation through physiochemical treatment methods such as ion implantation, the ultraviolet rays and mutagen, finally obtains the YS-L613 strain for high-yield production of the laccase, and adopts experimental automatic control technology, strain fermentation control technology and strain extraction technology to develop laccase products. As proved by experiments of the laccase in pulp bleaching, fiber modification and pulp deinking, utilization of the laccase in the paper-making industry can improve the quality of paper, reduce environmental pollution and save the cost.

A hydrogen peroxide stabilizer composition in paper pulp bleaching contains the following materials by the weight percentages: ethylenediaminetetraacetic acid 8%-10%, polyacrylic acid 3%-5%, nitrilortiacetic acid 5%-10%, hydroxy ethylidene-1, 1-diphosphonic acid 5%-8%, sodium hydroxide in suitable amount and the rest of deionized water,. The preparation method includes: mixing the materials in the material ratio, adjusting the pH value to 6.8-7.1 with the sodium hydroxide and adding the deionized water to 100%. The inventive hydrogen peroxide stabilizer composition in the paper pulp bleaching can reduce the decomposition rate of the hydrogen peroxide to less than 20%, prevent the fouling from generating and dispersing pulp fibers and chelating metal ions.

A method of bleaching chemical pulp with xylanase after chemical bleaching is provided. The method comprises the steps of exposing chemical pulp to a chlorine dioxide bleaching stage to produce a partially bleached pulp, treating the partially bleached pulp with a xylanase in an enzyme treatment stage at a pH of about 3 to about 8, then carrying out an alkaline extraction of the pulp. 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 a pulp-bleaching technique. 40 percent to 50 percent by weight of residual lignin of boiled pulp is removed by way of oxygen delignification, hydrogen peroxide is then utilized to further remove the lignin, and finally, calcium hypochlorite is used for supplementary bleaching. The yield of bleached pulp is high, moreover, the whiteness of bleached pulp is high, the stability of whiteness is good, and the pollution load of bleaching waste liquor is low.

The invention discloses a fermentation production method of fungal laccase and an application of the laccase. The method comprises the following steps: preparing Panus conchatus suspension; inoculating the suspension into a fermentation tank containing 3-5L of fermentation medium and culturing for 10-15 days, thus obtaining fermentation liquor; and finally, filtering or centrifuging the fermentation liquor, thus obtaining a laccase preparation. The method of the invention is simple and convenient in subsequent treatment of the fermentation liquor and low in production cost, and the activity of the Panus conchatus laccase obtained through fermentation is over 200IU/mL. Compared with other domestic and overseas laccase production methods in a fermentation tank scale, the fermentation production method of the fungal laccase, which is disclosed by the invention, has the advantages that the total laccase yield and the laccase activity reach a relatively high level, and the prepared laccase preparation has a good pulp bleaching effect.

The invention relates to a preparation process of chlorine dioxide used for pulp bleaching and a corresponding apparatus. The invention adopts sodium chlorate, sulfuric acid and methyl alcohol as materials which are mixed according to a certain proportion for reaction to generate chlorine dioxide and acid mirabilite. The chlorine dioxide is absorbed by iced water to generate the chlorine dioxide solution; the by-product mirabilite suspension is filtered by a rotary-drum vacuum filter to filter the mirabilite crystal out and then the mother solution and the filter solution are collected by a mother solution tank to return to the reactor for recycling use and the mirabilite crystal is directly diluted by black liquor. The invention has the beneficial effects that the process is simple; the productivity and reaction efficiency are high; the material cost is low; the productivity adaptability is high; the purity of chlorine dioxide is high; the content of chlorine is low; as the by-product of the preparation process, the mirabilite can be consumed in the paper mill so as to reduce the emission of contamination.

The invention relates to a technology for catalyzing and bleaching paper pulp with immobilized Schiff alkali metals, belonging to the technology for catalyzing and bleaching paper pulp. The method provided by the invention can ensure that paper pulp is catalyzed and bleached under a condition that immobilized Schiff alkali metals exist in a paper pulp bleaching treatment; and simultaneously peroxy acid and alcohol are added. The method provided by the invention is simple, is carried out easily, and is featured with remarkably effects; and the paper pulp bleaching effect is good.

The invention provides a denaturizing production technique of paper making bleaching wood pulp plate, which solves the problems of uneven dipping, slow hemicelluloses stripping, difficult accumulation descending, uneven cooking, single cooking method, single bleaching method and violent conditions existing in denaturizing production technique of wood pulp in the prior art. The invention comprises the following steps: wood pulp plate paging, alkali soaking, pressing, untwining and dispersion, cooking, washing, impurity removal, bleaching, a secondary washing and pulping; wherein, the wood pulp plate paging, alkali soaking, pressing, untwining and dispersion are to send papers into a alkali dipping barrel with concentration of 8 percent to 18 percent after the paper making bleaching wood pulp plates are separated by a paging device. When the wood pulp plates are changed into pulp with concentration of 3 percent to 7 percent, the pulp with concentration of 3 percent to 7 percent is sent to a squeezer to be squeezed and untwine and disperse fiber. By adopting the invention, the quality of the dissolved viscose fiber wood pulp can be better and more stable; furthermore, the invention provides wider selection range of raw material.

The present invention discloses a paper pulp bleaching equipment use method which comprises the following steps: (1) paper pulp to be bleached is added into a material storage hopper; (2) a power source of a feeding mechanism in the material storage hopper is started and the paper pulp in the material storage hopper is sent into a bleaching tower through a lower portion of the bleaching tower via a feed sending channel by screw blades; (3) while the step 2 is conducted, a bleaching agent in a bleaching tank is pumped into a hollow chamber body of a rotary shaft and is ejected out from a spray hole; and (4) a bleaching pulp treated by bleaching can thereby be obtained at a discharge port of the upper part of the bleaching tower. The scheme can avoid bridge of the paper pulp in the bleaching tower.