Treatment of the filtrate after bleaching the pulp with hydrogen peroxide
Processing relates to a method of bleaching cellulose and can be used in the pulp and paper industry. Cellulose is subjected to stage bleaching with hydrogen peroxide, after which it is washed and the wash liquid after washing is separated from the pulp in the form of a filtrate. Then the filtrate is treated with a compound of aluminum to precipitate interfering substances. The precipitated material is removed from the filtrate. The content of aluminum in the filtrate after precipitation of interfering substances establish the largest 20 parts per thousand, and the filtrate is then sent for recycling on stage peroxide bleaching. The technical result is to reduce the consumption of hydrogen peroxide on stage peroxide bleaching. 9 C.p. f-crystals, 3 tables. Description text in facsimile form (see graphic part).
Claims1. The method of bleaching cellulose in which the cellulose is subjected to a stage of bleaching peroxide, after which the pulp is washed and the washed liquid after washing is separated from the pulp in the form of a filtrate, wherein the filtrate is treated with a compound of aluminum to precipitate interfering substances, saidabout most 20 ppm, and the filtrate is then sent for recycling on stage peroxide bleaching.2. The method according to p. 1, characterized in that the filtrate, recirculating stage peroxide bleaching, includes connection, which together with aluminum contains alkaline earth metal.3. The method according to p. 2, characterized in that the alkaline earth metal is magnesium.4. The method according to p. 3, characterized in that the molar ratio of SB:A1 is 3:1 to 6:1.5. The method according to p. 3 or 4, characterized in that the compound containing aluminum, is hydrotalcite General formula[Mg1-xAlx(OH)2]x+[(CO3)x/2ĚnH2O]x-,where to 0.10<x<0.34, n=1-3x/2.6. The method according to any one of paragraphs.1-5, characterized in that the filtrate is treated with a compound of aluminum selected from the group consisting of aluminum chloride, aluminum nitrate, aluminum sulfate, chloride of polyalanine, nitrate of polyalanine and sulphate of polyalanine.7. The method according to any one of paragraphs.1-6, characterized in that the filtrate is treated with a compound of aluminum, which is added to the filtrate in a quantity at least sufficient to basically precipitate interfering substances.8. The method according to p. 7, characterized in that the compound of aluminium is added to the filtrate in the amount of 1 - 600 mg A1/l filter the application of aluminum is carried out at pH 4 - 11.10. The method according to any one of the preceding paragraphs, characterized in that the processing of the filtrate connection of aluminum is carried out at a temperature in the range 60 - 100C.
FIELD: pulp-and-paper industry, in particular method for PULP whitening.
SUBSTANCE: craft pulp mass with concentration of 2.5-5.0 % after oxygen-alkaline treatment is treated with potassium permanganate in consumption of 0.01-0.1 % based on dry cellulose at 40-80°C and pH 1.6-3.0 or with sulfuric acid solution in consumption of 1.0-1.5 % at 90°C for 30 min. In steps II and IV cellulose with concentration of 10 % is treated with hydrogen peroxide in consumption of 2 % based on mass of dry cellulose for 120 min at 80-90°C and pH 9.5-10.5 wherein consumption of sodium alkali and sodium silicate is 1.3 % and 2.5 %, respectively. In step III cellulose is treated with potassium permanganate in consumption of 0.01-0.4 % under step I conditions.
EFFECT: reduced consumption of whitening agents.
1 tbl, 9 ex
FIELD: pulp-and-paper industry, in particular method for pulp whitening.
SUBSTANCE: pulp mass with concentration of 5-10 % after oxygen-alkaline treatment in step I is treated with sulfuric acid in consumption of 5 % based on dry cellulose mass and pH 2.6-3.0. In step II peroxide treatment is carried out in alkali consumption of 1.0-1.3 % based on dry cellulose mass, and in step III pulp is treated with chlorine dioxide in consumption of 1.0-1.6 % based on dry cellulose mass at 70°C.
EFFECT: pulp with increased whiteness.
1 tbl, 17 ex
FIELD: pulp-and-paper industry.
SUBSTANCE: unbleached sulfate cellulose obtained from hardwood is subjected oxygen-alkali delignification, after which treated with chlorine dioxide in presence of oxyethylidenediphosphonic acid and then consecutively hydrogen peroxide and chlorine dioxide solutions. Process may be used in production of bleached fibrous intermediates.
EFFECT: increased whiteness and strength characteristics of cellulose and improved environmental safety of bleaching process.
2 cl, 1 tbl
FIELD: paper-and-pulp industry.
SUBSTANCE: cellulose delignification process comprises alkali treatment, delignification with hydrogen peroxide with sodium hydroxide and sodium silicate additive, and acid treatment. Alkali treatment consumes 0.5% hydrogen peroxide and 2.0% sodium hydroxide based on the weight of absolutely dry cellulose and is conducted for 2.0-2.5 h at 60-90°C. Acid treatment of delignified product is accomplished with aqueous hydrochloric acid, which is consumed in amount 1.0% based on the weight of absolutely dry fibers, while treatment is conducted for 30-60 min at ambient temperature.
EFFECT: enhanced economical efficiency without loss cellulose characteristics.
2 tbl, 11 ex
FIELD: textile, paper.
SUBSTANCE: method is referred to bleached wood pulp production from hardwood chips for their further use in different compositions for paper and cardboard production. Chipped wood is impregnated with alkali solution of sodium sulfite. Spent impregnating solution is then removed. Chipped wood is milled in two stages. In between components are treated by alkali solution of hydrogen peroxide at weight concentration 14-18% and final pH=9.5-10.0. Following the second stage of milling, pulp is dissolved to concentration 3.0-5.0% and cured during 30-60 minutes to pH=7.5-8.0. Pulp is chemically treated by alkali solution of hydrogen peroxide between milling stages at 75-85°C during 15-20 minutes.
EFFECT: decrease of chemicals consumption for impregnation and improvement of mechanical and optical properties of target product.
2 cl, 1 tbl, 4 ex
FIELD: paper industry.
SUBSTANCE: cellulose containing material from herbaceous plants is soaked in alkaline solution, washed, bleached, again washed, squeezed and dried. After soaking thermal-mechanical-chemical treatment is carried out in double-auger device, which consists of heated working chamber with impermeable wall and two parallel joined shafts arranged in it. Alternating injection auger and grinding cam tips are installed on shafts. At the same time prior to washing they additionally execute thermal-mechanical-chemical treatment in double-auger device, on shafts of which there are alternating injection and braking auger tips.
EFFECT: invention provides for cost-efficient method of cellulose making.
2 cl, 1 tbl
SUBSTANCE: absorbent material is made by treating lignin-cellulose material in the presence of a catalyst from a transition metal with oxidation. The oxidising agent is selected from a group consisting of hydrogen peroxide, hypochlorite, hypochloric acid or any combination thereof. The lignin-cellulose material is treated at pH from approximately 2 to approximately 6. The treated lignin-cellulose material has viscosity equal to or less than approximately 17 cP. The treated lignin-cellulose material is subjected to dry grinding. The dry ground lignin-cellulose treated material is used as an absorbent intermediate layer for making absorbents.
EFFECT: improved bacteria inhibition properties.
2 cl, 17 ex, 16 tbl
FIELD: textile, paper.
SUBSTANCE: method relates to production of mechanical or chemical-mechanical wood pulp applied as raw material for manufacturing of paper or cardboard, and may be used and pulp and paper industry. According to this method wood pulp is exposed to fibrillation. Produced wood pulp is screened to separate wastes from acceptable materials. At the same time wastes are removed in amount of maximum 60% of overall amount of wood pulp. Wastes and acceptable material are bleached separately. Wastes are bleached with the help of peroxide or peroxy acid. After that bleached wastes are mixed with bleached acceptable material. After combination they are exposed to finishing grinding, at the same time amount of consumed energy makes approximately 10-1000 kW-hr/ton. Finishing grinding is carried out at low concentration. Then wood pulp is batched into paper- or cardboard-making machine. Wastes are bleached in alkaline medium.
EFFECT: improved strength of wood pulp and reduction of energy consumed for grinding.
12 cl, 1 dwg, 1 ex
SUBSTANCE: method involves treating cellulose with sulphuric acid at the first step after oxygen-alkaline treatment. At the second step, peroxide bleaching is carried out in an alkaline medium in the presence of a stabiliser - magnesium sulphate. The third step involves treating cellulose with chlorine dioxide with its consumption not more than 0.5% for hardwood pulp and with chlorine dioxide consumption of 0.5-0.7% of the weight of absolutely dry cellulose for soft wood pulp. At the fourth step, cellulose is treated with hydrogen peroxide in an alkaline medium.
EFFECT: reduced consumption of chlorine dioxide, reduced corrosion of equipment and high environmental safety of the process.
1 tbl, 7 ex
FIELD: textile, paper.
SUBSTANCE: method is carried out by means of subsequent soaking of cellulose-containing herbal raw materials in alkaline solution, thermomechanical treatment, squeezing, washing, bleaching, squeezing, washing, squeezing and drying, besides, squeezing and washing are done in pulsating centrifuge.
EFFECT: higher yield of cellulose, reduced norms of consumption of initial reagents and water and reduced power inputs.
1 tbl, 3 ex