In order to reduce the production cost of traditional kenaf chemical pulping while maintaining the quality of chemical pulp, the following two measures can be used: (1) improving the storage method of hemp bast fiber; (2) innovative paddle method, from chemistry Pulping is changed to chemical-mechanical pulping, ie alkaline peroxide-extrusion pulping. Researchers at the Netherlands Agricultural Technology Research Institute have experimented with the use of kenaf, jute and hemp bast fibers as raw materials to produce flaxseed pulp using an alkaline hydrogen peroxide extrusion-slurry method.
Preparation: The hemp raw materials cut about 20mm, moisture content of about IO%.
Impregnation and preheating: The hemp raw material is soaked with 15 cC water for 16 h before extrusion pulping. After dipping the water and washing the material, it is preheated with saturated steam at atmospheric pressure.
Extrusion pulping: Modified C1extra I-BC45 extrusion pulping equipment. Chemical dosage: Hydrogen peroxide 4.0%, Sodium hydroxide 3.5%, Sodium silicate 3.0% and DPA 0.1%. The screw speed was 200r/min. The pulping was performed in the first extruder with a solids concentration of 30%.
Pulp Bleaching: Bleaching pulp with alkaline hydrogen peroxide is mainly carried out in a second extrusion paddler, adding bleach to the extruder, using a pump to dilute the bleach 1% (by H202, NaOH, Na2Si03 and DPA The composition) is fed to the secondary disintegrating fiber zone in the first extruder, and before entering the second extruder, the continuously bleached pulp is kept at a temperature of 700C for 30 minutes, in the second extruder, A 3% thick bleach solution was mixed with the slurry. At a temperature of 700C, the continuously bleached pulp was kept for 30 minutes, followed by washing the slurry with cold water.
Alkaline hydrogen peroxide-extruded pulp can be competed with wood pulp in the production of various types of paper. Characteristics of the production of fluff pulp with alkaline peroxide-hydrogen-extrusion pulping method:
(1) The yield of pulp is as high as 80%, the raw material consumption per ton of pulp is 1.25 tons, which is 0.75 tons lower than that of chemical pulp;
(2) The amount of chemicals used is relatively low, and the weight of raw materials calculated with sodium hydroxide is 4%-8%, while that of chemical pulp is 20%;
(3) Less water consumption, 15m3/t pulp;
(4) The energy consumption is higher than that of chemical pulp, and is lower than that of chemical mechanical pulp, and is 800-1200kwh/t pulp;
(5) Bleaching of flax pulp is easier and bleaching with hydrogen peroxide is used. Whiteness of bleached pulp can reach 83% IS0.
(6) The residual lignin content in bleached pulp is 2%-3%;
(7) An anaerobic and aerobic secondary biological wastewater treatment system is adopted to make the discharged water non-toxic and meet the requirements of the emission regulation standards; (8) Non-cellulosic compounds exist in the pulp, and machinery is produced in the extrusion pulping process. The shearing effect on the fiber makes the opacity of the prepared paper sheet higher. When the whiteness of bleached pulp is 83% ISO, the opacity is the same as that of chemical wood pulp;
(9) During the extrusion pulping process, cutting the fibers to the desired length at the same time does not grind the fibers and therefore does not significantly reduce the dewatering performance of the fibers, which is evident between the extrusion and the refining Difference;
(10) As the hemp fiber is harder and some non-cellulose compounds remain on the surface, the surface fibers of the paper sheet are poorly bonded to each other, affecting the dry and wet strength;
(11) This method is suitable for small-scale factory applications. The hemp bast fiber pulp prepared by the basic hydrogen peroxide extrusion-slurry method is suitable for copying the following paper types: non-coated writing paper, wood-free coated paper, wood-containing coated paper, and low-quantity Coated paper, tissue paper, toilet paper, etc.
Preparation: The hemp raw materials cut about 20mm, moisture content of about IO%.
Impregnation and preheating: The hemp raw material is soaked with 15 cC water for 16 h before extrusion pulping. After dipping the water and washing the material, it is preheated with saturated steam at atmospheric pressure.
Extrusion pulping: Modified C1extra I-BC45 extrusion pulping equipment. Chemical dosage: Hydrogen peroxide 4.0%, Sodium hydroxide 3.5%, Sodium silicate 3.0% and DPA 0.1%. The screw speed was 200r/min. The pulping was performed in the first extruder with a solids concentration of 30%.
Pulp Bleaching: Bleaching pulp with alkaline hydrogen peroxide is mainly carried out in a second extrusion paddler, adding bleach to the extruder, using a pump to dilute the bleach 1% (by H202, NaOH, Na2Si03 and DPA The composition) is fed to the secondary disintegrating fiber zone in the first extruder, and before entering the second extruder, the continuously bleached pulp is kept at a temperature of 700C for 30 minutes, in the second extruder, A 3% thick bleach solution was mixed with the slurry. At a temperature of 700C, the continuously bleached pulp was kept for 30 minutes, followed by washing the slurry with cold water.
Alkaline hydrogen peroxide-extruded pulp can be competed with wood pulp in the production of various types of paper. Characteristics of the production of fluff pulp with alkaline peroxide-hydrogen-extrusion pulping method:
(1) The yield of pulp is as high as 80%, the raw material consumption per ton of pulp is 1.25 tons, which is 0.75 tons lower than that of chemical pulp;
(2) The amount of chemicals used is relatively low, and the weight of raw materials calculated with sodium hydroxide is 4%-8%, while that of chemical pulp is 20%;
(3) Less water consumption, 15m3/t pulp;
(4) The energy consumption is higher than that of chemical pulp, and is lower than that of chemical mechanical pulp, and is 800-1200kwh/t pulp;
(5) Bleaching of flax pulp is easier and bleaching with hydrogen peroxide is used. Whiteness of bleached pulp can reach 83% IS0.
(6) The residual lignin content in bleached pulp is 2%-3%;
(7) An anaerobic and aerobic secondary biological wastewater treatment system is adopted to make the discharged water non-toxic and meet the requirements of the emission regulation standards; (8) Non-cellulosic compounds exist in the pulp, and machinery is produced in the extrusion pulping process. The shearing effect on the fiber makes the opacity of the prepared paper sheet higher. When the whiteness of bleached pulp is 83% ISO, the opacity is the same as that of chemical wood pulp;
(9) During the extrusion pulping process, cutting the fibers to the desired length at the same time does not grind the fibers and therefore does not significantly reduce the dewatering performance of the fibers, which is evident between the extrusion and the refining Difference;
(10) As the hemp fiber is harder and some non-cellulose compounds remain on the surface, the surface fibers of the paper sheet are poorly bonded to each other, affecting the dry and wet strength;
(11) This method is suitable for small-scale factory applications. The hemp bast fiber pulp prepared by the basic hydrogen peroxide extrusion-slurry method is suitable for copying the following paper types: non-coated writing paper, wood-free coated paper, wood-containing coated paper, and low-quantity Coated paper, tissue paper, toilet paper, etc.
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