Oxygen delignify treating method for grass group unbleached chemical pulp

Abstract

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.

Description

technical field

[0001] The invention relates to a treatment method of grass chemical pulp before bleaching, in particular, the invention relates to an oxygen delignification treatment method of grass unbleached chemical pulp. Background technique

[0002] At present, most of the world's pulp raw materials are wood, especially in developed countries such as the United States, Canada, Nordic countries and Russia, almost all of which are made of wood. As the demand for lumber increases year by year, the price of lumber also continues to rise. Many countries with low timber resources need to import large quantities of timber, and even countries with abundant timber resources, such as Canada, are expected to have a shortage of logs before long. Therefore, the problem of raw materials has become a major issue in the development of pulping industry in various countries, and the source of pulping raw materials is also expanding.

[0003] The technology of making pulp with grass fi...

Examples

Embodiment 1

[0025] The wheat straw is cooked by the ammonium sulfite method, specifically 4% sodium hydroxide solution is used for pre-impregnation, the ammonium sulfite solution is added to 10% of the dry raw material, the liquid ratio is 1:4, and the temperature is raised to 110 for the first time. ℃, keep warm at this temperature for 20 minutes, then let off steam for 20-30 minutes, heat up the temperature for 30 minutes to 168 ℃, and keep warm for 90 minutes. The pulp after cooking is washed and thickened to obtain unbleached chemical pulp with a hardness of potassium permanganate value of 20, relative kappa value of 31, degree of percussion of 22°SR, and concentration of 10%, and then heated by a screw conveyor The slurry is brought to 70°C and sent to the medium consistency slurry pipe. The pulp is subjected to conditioning treatment in the medium-consistency stock pipe to remove the air in the pulp to make it fluidized, and then transported to the oxygen delignification reaction to...

Embodiment 2

[0027]The rice straw is cooked by the caustic soda-anthraquinone method, specifically the addition of caustic soda solution is 10% of the absolute dry raw material, the anthraquinone addition is 0.7% of the absolute dry raw material, the liquid ratio is 1:4, and the temperature is raised for the first time To 110°C, keep warm at this temperature for 20 minutes, then let off steam for 20-30 minutes, heat up for the second time for 30 minutes to 168°C, and keep warm for 90 minutes. The cooked pulp is washed and thickened to obtain unbleached chemical pulp with a hardness of potassium permanganate value of 22, which is equivalent to a Kappa value of 35, a degree of percussion of 24°SR, and a concentration of 12%. The pulp is then heated to 70 ℃ and transported to the oxygen delignification reaction tower through a volumetric medium thick slurry pump. Before entering the reaction tower, the slurry is mixed with 40kg of added oxygen per ton of slurry and 2% sodium hydroxide of dry ...

Embodiment 3

[0029] Cook the cotton stalks by the sodium sulfite method, specifically adding 5% of total acid and 1.0-3.0% of combined acid to the cooking liquid, heating it up to 115°C for the first time, keeping it warm at this temperature for 20 minutes, and letting off steam for 20-30 minutes. Minutes, the second heating was carried out for 30 minutes to a temperature of 165°C, and the temperature was kept for 60 minutes. The cooked pulp is washed and thickened to obtain an unbleached chemical pulp with a hardness of 16, a knockout degree of 26°SR, and a concentration of 18%. The pulp is then heated to 80°C and transported to the pulp tower. In the pulp tower, the pulp is first subjected to tempering treatment to remove the air in the pulp to make it fluidized, and then it is transported to the first oxygen delignification reaction tower through a centrifugal medium-consistency pump, and 15kg per ton of pulp is added before entering the tower. Oxygen and 2% sodium hydroxide by dry pulp...

technical field

[0001] The invention relates to a treatment method of grass chemical pulp before bleaching, in particular, the invention relates to an oxygen delignification treatment method of grass unbleached chemical pulp. Background technique

[0002] At present, most of the world's pulp raw materials are wood, especially in developed countries such as the United States, Canada, Nordic countries and Russia, almost all of which are made of wood. As the demand for lumber increases year by year, the price of lumber also continues to rise. Many countries with low timber resources need to import large quantities of timber, and even countries with abundant timber resources, such as Canada, are expected to have a shortage of logs before long. Therefore, the problem of raw materials has become a major issue in the development of pulping industry in various countries, and the source of pulping raw materials is also expanding.

[0003] The technology of making pulp with grass fi...

Examples

Embodiment 1

[0025] The wheat straw is cooked by the ammonium sulfite method, specifically 4% sodium hydroxide solution is used for pre-impregnation, the ammonium sulfite solution is added to 10% of the dry raw material, the liquid ratio is 1:4, and the temperature is raised to 110 for the first time. ℃, keep warm at this temperature for 20 minutes, then let off steam for 20-30 minutes, heat up the temperature for 30 minutes to 168 ℃, and keep warm for 90 minutes. The pulp after cooking is washed and thickened to obtain unbleached chemical pulp with a hardness of potassium permanganate value of 20, relative kappa value of 31, degree of percussion of 22°SR, and concentration of 10%, and then heated by a screw conveyor The slurry is brought to 70°C and sent to the medium consistency slurry pipe. The pulp is subjected to conditioning treatment in the medium-consistency stock pipe to remove the air in the pulp to make it fluidized, and then transported to the oxygen delignification reaction to...

Embodiment 2

[0027]The rice straw is cooked by the caustic soda-anthraquinone method, specifically the addition of caustic soda solution is 10% of the absolute dry raw material, the anthraquinone addition is 0.7% of the absolute dry raw material, the liquid ratio is 1:4, and the temperature is raised for the first time To 110°C, keep warm at this temperature for 20 minutes, then let off steam for 20-30 minutes, heat up for the second time for 30 minutes to 168°C, and keep warm for 90 minutes. The cooked pulp is washed and thickened to obtain unbleached chemical pulp with a hardness of potassium permanganate value of 22, which is equivalent to a Kappa value of 35, a degree of percussion of 24°SR, and a concentration of 12%. The pulp is then heated to 70 ℃ and transported to the oxygen delignification reaction tower through a volumetric medium thick slurry pump. Before entering the reaction tower, the slurry is mixed with 40kg of added oxygen per ton of slurry and 2% sodium hydroxide of dry ...

Embodiment 3

[0029] Cook the cotton stalks by the sodium sulfite method, specifically adding 5% of total acid and 1.0-3.0% of combined acid to the cooking liquid, heating it up to 115°C for the first time, keeping it warm at this temperature for 20 minutes, and letting off steam for 20-30 minutes. Minutes, the second heating was carried out for 30 minutes to a temperature of 165°C, and the temperature was kept for 60 minutes. The cooked pulp is washed and thickened to obtain an unbleached chemical pulp with a hardness of 16, a knockout degree of 26°SR, and a concentration of 18%. The pulp is then heated to 80°C and transported to the pulp tower. In the pulp tower, the pulp is first subjected to tempering treatment to remove the air in the pulp to make it fluidized, and then it is transported to the first oxygen delignification reaction tower through a centrifugal medium-consistency pump, and 15kg per ton of pulp is added before entering the tower. Oxygen and 2% sodium hydroxide by dry pulp...