A mixed pulping process of wood fiber and recycled pulp

Abstract

The invention discloses a mixed pulping process of wood fiber and recycled pulp, which comprises the following steps: disintegration and slag removal: wood fiber and recycled pulp are put into a chain plate machine in a ratio of 1: (0.5-0.8), and a vertical hydraulic pulper is used for pulping and disintegration, the disintegration concentration is 5.5%-6%, the dilution white water is heated by steam to control the disintegration temperature at 65-70°C, and liquid alkali with a pH value greater than 6.2 is added to ensure the swelling of the fiber and improve the fiber morphology and toughness; after disintegration, the pulp is treated by a high-concentration slag remover. Impurities and coarse fiber bundles are screened and removed, and the slag can be thrown into the waste paper line for recycling and reuse; refining: choose the grinding disc suitable for coarse fiber refining, and obtain the regenerated pulp / wood fiber mixed refining with good refining effect by controlling high refining concentration and high reflux rate; dilute the regenerated pulp / wood fiber mixed refining to a concentration of 2.3-2.8%, and then add it directly to the long fiber multi-disc concentrator of the OCC waste paper line, and add it to the bottom pulp after further refining treatment with the waste paper pulp through long fiber heat dispersion and disc refiner.

Description

Technical field:

[0001] The invention relates to the technical field of pulping and papermaking, in particular to a mixed pulping process of wood fiber and regenerated pulp. Background technology:

[0002] In order to survive and develop, domestic enterprises actively seek alternative raw materials, including processing wood fiber and waste paper into recycled pulp that meets import standards after simple hot grinding of wood chips. Wood fiber has the advantages of simple production process and low cost, but because it does not remove impurities such as lignin that have a significant impact on papermaking, the bulk and air permeability of the produced paper increase, and the strength and bonding force decrease significantly.

[0003] One of the traditional ways to add wood fiber is to mix it with waste paper in proportion and then process it through crushing, screening, purification and pulping. However, due to its fiber structure characteristics, it leads to large loss in the screening section, resulting in waste, and the poor pulping effect affects the papermaking index. Alternatively, the wood fiber is crushed and refined separately and then mixed with waste paper pulp. The pulping effect is improved, but it brings problems such as increased energy consumption and large loss of equipment (mainly disc grinding).

[0004] Therefore, it is of great significance for packaging paper manufacturers to seek a wood fiber processing technology that can not only ensure the pulping effect but also solve the problems of high energy consumption and equipment loss.

[0005] In view of this, the inventor proposes the following technical solution. Summary of the invention:

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a mixed pulping process of wood fiber and recycled pulp.

[0007] In order to solve the above technical problems, the present invention adopts the following technical scheme: the mixed pulping process of wood fiber and recycled pulp includes the following steps: crushing and deslagging: wood fiber and recycled pulp are put into the chain plate machine in a ratio of 1: (0.5-0.8), and the pulp is crushed and deslagging is carried out by a vertical hydraulic pulper, the crushing concentration is 5.5%-6%, the dilution white water is heated by steam to control the crushing temperature at 65-70°C, and liquid alkali with a pH>6.2 is added at the same time to ensure the swelling of the fiber and improve the fiber morphology and toughness; after crushing, the impurities and coarse fiber bundles in the pulp are removed by a high-concentration deslagging device The waste pulp is screened and removed and enters the pre-beating tank, and the slag can be thrown into the waste paper line for recycling and reuse; refining: select the grinding disc suitable for coarse fiber refining, and obtain the regenerated pulp / wood fiber mixed refining with good refining effect by controlling the high refining concentration and high reflux rate, and enter the post-beating tank; after the regenerated pulp / wood fiber mixed refining in the post-beating tank is diluted to a concentration of 2.3-2.8%, it is directly added to the long fiber multi-disc concentrator of the OCC waste paper line, and after further refining treatment with the waste paper pulp through long fiber heat dispersion and disc refiner, it is added to the bottom pulp to form the bottom pulp required for the papermaking process of the paper machine.

[0008] Furthermore, in the above technical scheme, during refining, the refining disc is selected as the domestic Yalu River TF4E48-3555; high refining concentration refers to the refining concentration of 5% to 5.5%; disc grinding power: 500 to 600 kw, high reflux flow refers to the reflux flow of 4000 to 5000 l / min; pressure difference: 30 to 80 kpa; processing capacity: 200 to 250 tons / day.

[0009] Furthermore, in the above technical solution, the freeness of the recycled pulp / wood fiber mixed pulp formed after pulping is: 750-800 ml at the inlet and 550-650 ml at the outlet, and the freeness is increased by 15-25%; the proportion of liquid alkali added is 10 kg / ton of absolute dry pulp.

[0010] Furthermore, in the above technical scheme, the process flow of the OCC waste paper line is: 100% domestic waste → chain conveyor → drum pulper → high-concentration cleaner → coarse screen → grading screen → low-concentration cleaner → fine screen → long-fiber multi-disc concentrator → hot dispersion → pre-beating pulp tank → disc grinding pulping → post-beating pulp tank → paper machine feeding system.

[0011] Furthermore, in the above technical scheme, the process of papermaking process of the paper machine is: paper machine feeding system → double-layer long-wire paper machine → four-roller three-pressure press → eight-group front cylinder drying system → film transfer sizing machine → three-group cylinder drying system → calender → winding → rewinding offline → coating machine → warehousing.

[0012] Furthermore, in the above technical scheme, the paper machine feeding system: the surface layer pulp and the bottom layer pulp from pulping are further screened and purified, and chemical auxiliary materials are added in the process to make the paper have the characteristics of use; the double-layer fourdrinier paper machine: the pulp is put on the net, and the surface layer pulp and the bottom layer pulp are dehydrated and formed by gravity and vacuum, with a dryness of 21-24%; the four-roller three-pressure press: the preliminarily dehydrated and formed wet paper web is further dehydrated by pressing, and the pressing includes vacuum pressing, blind roller pressing and shoe pressing, with a dryness of 48-52%; the eight-group front drying cylinder drying system: as the front drying section, the moisture of the paper web is dried by steam, and the dryness is 88-92%; the film transfer sizing machine: the surface of the paper web is covered with starch sizing material, starch The glue fills the surface pores of the paper sheet, reducing the pore size, thereby reducing the penetration of liquids and giving the paper a certain strength and water resistance. The three-cylinder drying system: as the post-drying section, the wet paper web is steam-dried and dehydrated after glue application, with a dryness of 90-92%. The calender: finishes the dried paper to improve the flatness, glossiness and tightness of the paper. Winding: the paper web is rolled into a roll at the end of the paper machine for storage and further processing. Rewinding: the large paper roll is cut into small paper rolls according to size requirements. The coating machine: a layer of 0.01-0.03mm thick stretch film is coated on the small paper rolls after rewinding and slitting to prevent the paper rolls from being damaged, dehydrated or dampened. Warehousing: storage in the warehouse and delivery as required.

[0013] Furthermore, in the above technical solution, the composition ratio of the starch sizing material is: 80-95% corn starch; 1.5-10% surface sizing agent; 0.02-0.05% active amylase; and 1.5-10% aluminum sulfate.

[0014] Furthermore, in the above technical solution, the component ratio of the surface layer pulp is 100% OCC waste paper pulp, wherein the raw material ratio of the OCC waste paper pulp is 40-60% domestic waste AB grade and 40-60% domestic waste CD grade; the component ratio of the bottom layer pulp is 12% recycled pulp / wood fiber mixed pulp and 88% OCC waste paper pulp, wherein the raw material ratio of the OCC waste paper pulp is 40-60% domestic waste AB grade and 40-60% domestic waste CD grade.

[0015] Furthermore, in the above technical scheme, the chemical auxiliary materials include dual retention and filtration aids, which include powder retention aid Nuoerpol8310 and liquid retention aid Nuoerform860, wherein the addition amount of powder retention aid Nuoerpol8310 to the surface layer slurry is 0.4-0.6 kg / ton of absolute dry slurry, and the addition amount of powder retention aid Nuoerpol8310 to the bottom layer slurry is 0.8-1.0 kg / ton of absolute dry slurry; the addition amount of liquid retention aid Nuoerform860 to the surface layer slurry is 0.3-0.4 kg / ton of absolute dry slurry, and the addition amount of liquid retention aid Nuoerform860 to the bottom layer slurry is 0.3-0.4 kg / ton of absolute dry slurry.

[0016] Furthermore, in the above technical solution, the powder retention aid Nuoerpol 8310 is a cationic high molecular weight polyacrylamide polymer particle; the liquid retention aid Nuoerform 860 is a water-soluble high molecular weight polyacrylamide derivative.

[0017] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0018] 1. The mixed pulping process of wood fiber and recycled pulp of the present invention is different from the general treatment method of single crushing and refining of wood fiber. The present invention adopts the method of mixed crushing and refining of wood fiber / recycled pulp. The soft fibers in the recycled pulp and the coarse and hard fibers in the wood fiber are fully mixed and stirred in the vertical hydraulic pulper and then enter the disc grinding for refining, which can obtain a better refining effect. At the same time, the addition of recycled pulp protects the grinding disc in the disc grinding, delays the use cycle of the grinding disc, increases its service life, reduces production costs, and improves competitiveness. Through mixed refining, the refining effect is improved by more than 10%, the folding resistance of the finished paper is improved by more than 50%, and the air permeability is reduced by more than 10%.

[0019] 2. Compared with the freeness of general wood fiber refining under the same parameters: 800-850ml at the inlet and 750-800ml at the outlet, the present invention only increases by 6-10%. The freeness of the regenerated pulp / wood fiber mixed refining prepared by the present invention: 750-800ml at the inlet and 550-650ml at the outlet, increases by 15-25%, that is, the increase ratio of the freeness of the regenerated pulp / wood fiber mixed refining is relatively large.

[0020] 3. In the present invention, after the wood fiber and the recycled pulp are mixed and crushed, they are passed through a separate high-concentration cleaner, which performs high-concentration cleaning to remove impurities and coarse fiber bundles, so that the mixed pulp itself contains fewer impurities and does not need to be cleaned together with the waste paper pulp in the OCC waste paper, which can reduce fiber loss by 10-20%; the wood fiber and recycled pulp are only added to the bottom layer of pulp, which ensures the appearance of the surface layer of pulp is clean and fine, so that the quality of the finished packaging paper made by the later paper machine is better. In addition, the mixed pulp of wood fiber and recycled pulp is directly added to the long fiber multi-disc thickener of the OCC waste paper line and then mixed with the bottom layer of pulp, so as to avoid problems such as cracking lines and dark color caused by adding the surface pulp, improve the quality of the paper, and because of the improvement of the quality of the paper, the amount of wood fiber can be increased by 20%, reducing the amount of waste paper pulp, which can save papermaking costs. Description of the drawings:

[0021] Figure 1 It is a flow chart of the present invention. Specific implementation method:

[0022] The present invention is further described below in conjunction with specific embodiments and drawings.

[0023] See Figure 1 As shown, a mixed pulping process of wood fiber and recycled pulp is provided, which comprises the following steps:

[0024] Crushing and deslagging: wood fiber and recycled pulp are fed into the chain conveyor 101 at a ratio of 1: (0.5-0.8), and the pulp is crushed and deslagging is carried out by a vertical hydraulic pulper 102. The crushing concentration is 5.5%-6%, and the dilution white water is heated by steam to control the crushing temperature at 65-70°C. At the same time, liquid alkali with a pH>6.2 is added to ensure the swelling of the fiber and improve the fiber morphology and toughness; wherein, the proportion of the liquid alkali added is 10kg / ton of absolute dry pulp; after crushing, the impurities and coarse fiber bundles in the pulp are screened and removed by the high-concentration deslagging device 103, and the pulp enters the fore-beating tank 104. The discharged slag can be fed to the waste paper line for recycling and reuse, achieving the effect of Jieheng environmental protection.

[0025] Refining: Select the grinding disc suitable for coarse fiber refining, and obtain the recycled pulp / wood fiber mixed refining with good refining effect by controlling the high refining concentration and high reflux rate, and then enter the post-refining pool 105; specifically, during refining, the grinding disc of the disc refiner 106 is the domestic Yalu River TF4E48-3555; high refining concentration refers to the refining concentration of 5% to 5.5%; disc refiner power: 500 to 600kw, high reflux rate refers to the reflux rate of 4000 to 5000l / min; pressure difference: 30 to 80kpa; processing capacity: 200 to 250 tons / day.

[0026] The recycled pulp / wood fiber mixed pulp in the tapping pool is diluted to a concentration of 2.3-2.8%, and then directly added to the long fiber multi-disc thickener of the OCC waste paper line. After further pulping treatment with the waste paper pulp through long fiber heat dispersion and disc refiner, it is added to the bottom pulp to form the bottom pulp required for the papermaking process of the paper machine.

[0027] In the crushing and deslagging steps, wood fiber and recycled pulp are fed into the chain conveyor in a ratio of 1: (0.5-0.8), specifically: 60% wood fiber + 40% recycled pulp.

[0028] The mixed pulping process of wood fiber and recycled pulp of the present invention is different from the general treatment method of single crushing and refining of wood fiber. The present invention adopts the method of mixed crushing and refining of wood fiber / recycled pulp. The soft fibers in the recycled pulp and the coarse and hard fibers in the wood fiber are fully mixed and stirred in the vertical hydraulic pulper and then enter the disc grinding for refining, which can obtain a better refining effect. At the same time, the addition of recycled pulp protects the grinding disc in the disc grinding, delays the use cycle of the grinding disc, increases its service life, reduces production costs, and improves competitiveness. Through mixed refining, the refining effect is improved by more than 10%, the folding resistance of the finished paper is improved by more than 50%, and the air permeability is reduced by more than 10%. Furthermore, compared with the freeness of general single wood fiber refining under the same parameters: 800-850ml at the inlet and 750-800ml at the outlet, it is only improved by 6-10%. The freeness of the mixed pulp / wood fiber made by the present invention is: 750-800ml at the inlet and 550-650ml at the outlet, which is increased by 15-25%, that is, the improvement ratio of the freeness of the mixed pulp / wood fiber is relatively large. In addition, after the wood fiber and the recycled pulp are mixed and crushed, they are passed through a separate high-concentration cleaner, which performs high-concentration cleaning to remove impurities and coarse fiber bundles, so that the mixed pulp itself contains fewer impurities, and does not need to be cleaned together with the waste paper pulp in the OCC waste paper, which can reduce the fiber loss by 10-20%; the wood fiber and the recycled pulp are only added to the bottom layer of pulp, which ensures the cleanliness and fineness of the appearance of the surface layer of pulp, so that the quality of the finished packaging paper made by the later paper machine is better. In addition, the mixed pulp of wood fiber and recycled pulp is directly added to the long fiber multi-disc concentrator of the OCC waste paper line and then mixed with the pulp at the bottom layer to avoid problems such as paper cracking and dark color caused by adding surface pulp, thereby improving the quality of paper. Due to the improvement in paper quality, the amount of wood fiber can be increased by 20%, reducing the amount of waste paper pulp and saving papermaking costs.

[0029] The addition ratio of the mixed pulp of wood fiber and recycled pulp can reach 12% to 18% of the whole raw materials, of which the wood fiber can reach 7% to 10%.

[0030] The process flow of the OCC waste paper line is: 100% domestic waste → chain conveyor 201 → drum pulper 202 → high-concentration cleaner 203 → coarse screen 204 → grading screen 205 → low-concentration cleaner 206 → fine screen 207 → long-fiber multi-disc thickener 208 → thermal dispersion 209 → pre-beating pulp tank 210 → disc grinding and beating 211 → post-beating pulp tank 212 → paper machine feeding system.

[0031] Specifically, the process flow of the OCC waste paper line is to feed 100% domestic waste raw materials into the chain conveyor, and then the chain conveyor transmits it to the drum pulper. The drum pulper crushes the domestic waste raw materials, and then passes through the high-concentration cleaner, which separates the metal and glass impurities in the pulp. Then it passes through the coarse screen, grading screen, low-concentration cleaner, and fine screen to further remove impurities in the pulp. Among them, the grading screen classifies the pulp into long-fiber pulp, medium-fiber pulp, and short-fiber pulp according to different fiber sizes. The long-fiber multi-disc concentrator removes part of the moisture in the long-fiber pulp, and after increasing the concentration, it enters the hot dispersion equipment for treatment. The hot dispersion equipment disperses the hot melt in the long-fiber pulp into particles invisible to the naked eye through the action of high temperature and mechanical force, so as to improve the appearance quality of the finished paper (i.e., high-end packaging paper). After the pulp is beaten by the disc grinder, it enters the post-beating pulp pool. Among them, after the recycled pulp / wood fiber mixed pulp is diluted to a concentration of 2.3-2.8%, it is directly added to the long fiber multi-disc concentrator of the OCC waste paper line, and the long fiber pulp in the waste paper pulp is further refined through long fiber heat dispersion and disc refiner, and then added to the bottom pulp to form the bottom pulp required for the papermaking process of the paper machine.

[0032] The papermaking process of the paper machine is as follows: paper machine feeding system → double-layer fourdrinier paper machine → four-roller three-pressure press → eight-group front cylinder drying system → film transfer sizing machine → three-group cylinder drying system → calender → winding → rewinding off line → film coating machine → storage. Each step is as follows:

[0033] Paper machine feeding system: the surface layer pulp and bottom layer pulp from pulping are further screened and purified, and chemical auxiliary materials are added in the process to make the finished paper have the characteristics that meet the use requirements; wherein the composition ratio of the surface layer pulp is 100% OCC waste paper pulp, wherein the raw material ratio of the OCC waste paper pulp is 40-60% domestic waste AB grade and 40-60% domestic waste CD grade; the composition ratio of the bottom layer pulp is 12% recycled pulp / wood fiber mixed pulping and 88% OCC waste paper pulp, wherein the raw material ratio of the OCC waste paper pulp is 40-60% domestic waste AB grade and 40-60% domestic waste CD grade.

[0034] The chemical auxiliary materials include dual retention and filtration aids, which include powder retention aid Nuoerpol8310 and liquid retention aid Nuoerform860, wherein the addition amount of powder retention aid Nuoerpol8310 to the surface layer slurry is 0.4-0.6kg / ton of absolute dry slurry, and the addition amount of powder retention aid Nuoerpol8310 to the bottom layer slurry is 0.8-1.0kg / ton of absolute dry slurry; the addition amount of liquid retention aid Nuoerform860 to the surface layer slurry is 0.3-0.4kg / ton of absolute dry slurry, and the addition amount of liquid retention aid Nuoerform860 to the bottom layer slurry is 0.3-0.4kg / ton of absolute dry slurry. The powder retention aid Nuoerpol8310 is a cationic high molecular weight polyacrylamide polymer particle, which has a strong fiber and fine fiber, filler flocculation ability, and improves the first-pass retention rate of paper sheets; the liquid retention aid Nuoerform860 is a water-soluble high molecular weight polyacrylamide derivative. It has the characteristics of high molecular weight and high cationic charge density, and has a good flocculation ability for various components in the pulp system to form fine microflocculations, which can quickly improve the dewatering performance of the paper machine's wire section. Therefore, the use of this dual retention aid can improve the retention of pulp fine fibers and papermaking fillers while improving the water filtration capacity of the wire section.

[0035] Double-layer Fourdrinier paper machine: The pulp is put on the net, and the surface pulp and bottom pulp are dehydrated and formed by gravity and vacuum, with a dryness of 21-24%;

[0036] Four-roll three-press press: The initially dehydrated and formed wet paper web is further dehydrated by pressing, which includes vacuum pressing, blind roll pressing and shoe pressing. The pressing effect is good and the dryness is 48-52%;

[0037] Eight groups of front drying cylinder drying system: as the front drying section, it dries the paper moisture through steam, and the dryness is 88-92%;

[0038] Film transfer sizing machine: The surface of the paper web is covered with starch sizing agent, which fills the surface pores of the paper sheet to form a starch film, reduces the micropore diameter, thereby reducing the penetration of liquid, giving the paper a certain strength and water resistance, thereby improving the printing performance, preventing hair loss and powder loss, and effectively improving the strength and dimensional stability of the finished paper; wherein, the composition ratio of the starch sizing agent is: 80-95% corn starch; 1.5-10% surface sizing agent; 0.02-0.05% active amylase; 1.5-10% aluminum sulfate. The film transfer sizing machine covers the surface of the paper web with starch sizing agent, which fills the surface pores of the paper sheet to form a starch film, which is surface sizing, and its purpose is: a. Pre-finishing the surface of the finished paper and improving the strength of the finished paper. b. Improving the performance of the finished paper and further improving the production efficiency. The retention rate of the added chemicals in the surface sizing agent is almost 100%. c. In terms of environmental friendliness, surface sizing has more advantages than wet-end additives. Surface sizing can reduce or eliminate chemicals in white water, which helps improve the environment. The requirements for the sizing tank of the film transfer sizing machine are: temperature 80-90℃, viscosity 150-300mpa.s, solid content 18-22%.

[0039] Three-cylinder drying system: as the post-drying section, it steam-dries and dehydrates the wet paper web after sizing, with a dryness of 90-92%;

[0040] Calender: Finish the dried paper to improve its flatness, glossiness and tightness;

[0041] Reeling: Winding the paper web into reels at the end of the paper machine for storage and further processing;

[0042] Rewinding: Cut the large paper roll into small paper rolls according to size requirements;

[0043] Coating machine: Coat the small paper roll after rewinding and slitting with a layer of 0.01-0.03mm thick stretch film to prevent the paper roll from being damaged, losing water or regaining moisture;

[0044] Warehousing: Add to warehouse storage and ship as needed.

[0045] According to the above production process plan, the paper index can be controlled within the following range (Jianglong recycled kraft paper 100-150g): moisture 8.0-9.0%, ring pressure 6-8N.m / g, COBB value: 30-40g, density 0.67-0.73g / cm3, air permeability 300-500cfm, interlayer bonding force 200-300J / m2, burst resistance 1.8-2.2kgf / cm2, folding endurance 10-15 times.

[0046] In summary, the mixed pulping process of wood fiber and recycled pulp of the present invention is different from the general treatment method of single crushing and refining of wood fiber. The present invention adopts the method of mixed crushing and refining of wood fiber / recycled pulp. The soft fibers in the recycled pulp and the coarse and hard fibers in the wood fiber are fully mixed and stirred in the vertical hydraulic pulper and then enter the disc grinding for refining, which can obtain a better refining effect. At the same time, the addition of recycled pulp protects the grinding discs in the disc grinding, delays the use cycle of the grinding discs, increases their service life, reduces production costs, and improves competitiveness. Through mixed refining, the refining effect is improved by more than 10%, the folding resistance of the finished paper is improved by more than 50%, and the air permeability is reduced by more than 10%. Furthermore, compared with the freeness of general single wood fiber refining under the same parameters: 800-850ml at the inlet and 750-800ml at the outlet, it is only improved by 6-10%. The freeness of the mixed pulp / wood fiber made by the present invention is: 750-800ml at the inlet and 550-650ml at the outlet, which is increased by 15-25%, that is, the improvement ratio of the freeness of the mixed pulp / wood fiber is relatively large. In addition, after the wood fiber and the recycled pulp are mixed and crushed, they are passed through a separate high-concentration cleaner, which performs high-concentration cleaning to remove impurities and coarse fiber bundles, so that the mixed pulp itself contains fewer impurities, and does not need to be cleaned together with the waste paper pulp in the OCC waste paper, which can reduce the fiber loss by 10-20%; the wood fiber and the recycled pulp are only added to the bottom layer of pulp, which ensures the cleanliness and fineness of the appearance of the surface layer of pulp, so that the quality of the finished packaging paper made by the later paper machine is better. In addition, the mixed pulp of wood fiber and recycled pulp is directly added to the long fiber multi-disc concentrator of the OCC waste paper line and then mixed with the pulp at the bottom layer to avoid problems such as paper cracking and dark color caused by adding surface pulp, thereby improving the quality of paper. Due to the improvement in paper quality, the amount of wood fiber can be increased by 20%, reducing the amount of waste paper pulp and saving papermaking costs.

[0047] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. All equivalent changes or modifications made according to the structure, characteristics and principles described in the patent application scope of the present invention should be included in the patent application scope of the present invention.

Claims

1. A process for mixing wood fiber and recycled pulp, characterized in that: It includes the following steps: Crushing and deslagging: Wood fiber and recycled pulp are fed into the chain conveyor at a ratio of 1: (0.5-0.8), and the pulp is crushed and deslagging is carried out by a vertical hydraulic pulper. The crushing concentration is 5.5%-6%. The diluted white water is heated by steam to control the crushing temperature at 65-70°C. At the same time, liquid alkali with a pH>6.2 is added to ensure the swelling of the fiber and improve the fiber morphology and toughness. After crushing, the impurities and coarse fiber bundles in the pulp are screened and removed by a high-concentration deslagging device and enter the fore-beating tank. The discharged slag can be fed to the waste paper line for recycling; Refining: Select the refining disc suitable for coarse fiber refining, and obtain the regenerated pulp / wood fiber mixed refining with good refining effect by controlling the high refining concentration and high reflux rate, and then enter the post-refining tank; The recycled pulp / wood fiber mixed pulp in the tapping pool is diluted to a concentration of 2.3-2.8%, and then directly added to the long fiber multi-disc thickener of the OCC waste paper line. After further pulping treatment with the waste paper pulp through long fiber heat dispersion and disc refiner, it is added to the bottom pulp to form the bottom pulp required for the papermaking process of the paper machine.

2. The process for mixing and refining wood fiber and recycled pulp according to claim 1, characterized in that: During refining, the refining disc is the domestically produced Yalujiang TF4E48-3555; high refining concentration refers to a refining concentration of 5% to 5.5%; disc grinding power: 500 to 600 kw; high reflux flow refers to a reflux flow of 4000 to 5000 l / min; pressure difference: 30 to 80 kpa; processing capacity: 200 to 250 tons / day.

3. The process for mixing and refining wood fiber and recycled pulp according to claim 1, characterized in that: The freeness of the recycled pulp / wood fiber mixed pulp formed after pulping is: 750-800ml at the inlet and 550-650ml at the outlet, and the freeness is increased by 15-25%; the proportion of liquid alkali added is 10kg / ton of absolute dry pulp.

4. A process for mixing and refining wood fiber and recycled pulp according to any one of claims 1 to 3, characterized in that: The process flow of the OCC waste paper line is: 100% domestic waste → chain conveyor → drum pulper → high-concentration cleaner → coarse screen → grading screen → low-concentration cleaner → fine screen → long-fiber multi-disc thickener → hot dispersion → pre-beating pulp tank → disc grinding pulping → post-beating pulp tank → paper machine feeding system.

5. A process for mixing and refining wood fiber and recycled pulp according to claim 4, characterized in that: The process of papermaking technology of paper machine is: paper machine feeding system → double-layer fourdrinier paper machine → four-roller three-pressure press → eight-group front cylinder drying system → film transfer sizing machine → three-group cylinder drying system → calender → winding → rewinding offline → coating machine → storage.

6. A process for mixing and refining wood fiber and recycled pulp according to claim 5, characterized in that: Paper machine feeding system: the surface pulp and bottom pulp from pulping are further screened and purified, and chemical auxiliary materials are added in the process to make the finished paper have the characteristics that meet the use requirements; Double-layer Fourdrinier paper machine: The pulp is put on the net, and the surface pulp and bottom pulp are dehydrated and formed by gravity and vacuum, with a dryness of 21-24%; Four-roll three-press press: The initially dehydrated and formed wet paper web is further dehydrated by pressing, which includes vacuum pressing, blind roll pressing and shoe pressing, with a dryness of 48-52%; Eight groups of front drying cylinder drying system: as the front drying section, it dries the paper moisture through steam, and the dryness is 88-92%; Film transfer sizing machine: The surface of the paper is covered with starch sizing agent, which fills the surface pores of the paper sheet, reduces the pore size, thereby reducing the penetration of liquids and giving the paper a certain strength and water resistance. Three-cylinder drying system: as the post-drying section, it steam-dries and dehydrates the wet paper web after sizing, with a dryness of 90-92%; Calender: Finish the dried paper to improve its flatness, glossiness and tightness; Reeling: Winding the paper web into reels at the end of the paper machine for storage and further processing; Rewinding: Cut the large paper roll into small paper rolls according to size requirements; Coating machine: Coat the small paper roll after rewinding and slitting with a layer of 0.01-0.03mm thick stretch film to prevent the paper roll from being damaged, losing water or regaining moisture; Warehousing: Add to warehouse storage and ship as needed.

7. A process for mixing and refining wood fiber and recycled pulp according to claim 6, characterized in that: The starch sizing material has the following component proportions: 80-95% corn starch; 1.5-10% surface sizing agent; 0.02-0.05% active amylase; and 1.5-10% aluminum sulfate.

8. The process for mixing and refining wood fiber and recycled pulp according to claim 6, characterized in that: The composition ratio of the surface layer pulp is 100% OCC waste paper pulp, wherein the raw material ratio of the OCC waste paper pulp is 40-60% domestic waste AB grade and 40-60% domestic waste CD grade; the composition ratio of the bottom layer pulp is 12% recycled pulp / wood fiber mixed pulp and 88% OCC waste paper pulp, wherein the raw material ratio of the OCC waste paper pulp is 40-60% domestic waste AB grade and 40-60% domestic waste CD grade.

9. A process for mixing and refining wood fiber and recycled pulp according to claim 6, characterized in that: The chemical auxiliary materials include dual retention and filtration aids, which include powder retention aid Nuoerpol8310 and liquid retention aid Nuoerform860, wherein the addition amount of powder retention aid Nuoerpol8310 to the surface layer slurry is 0.4-0.6kg / ton of absolute dry slurry, and the addition amount of powder retention aid Nuoerpol8310 to the bottom layer slurry is 0.8-1.0kg / ton of absolute dry slurry; the addition amount of liquid retention aid Nuoerform860 to the surface layer slurry is 0.3-0.4kg / ton of absolute dry slurry, and the addition amount of liquid retention aid Nuoerform860 to the bottom layer slurry is 0.3-0.4kg / ton of absolute dry slurry.

10. A process for mixing and refining wood fiber and recycled pulp according to claim 9, characterized in that: Powder retention aid Nuoerpol8310 is a cationic high molecular weight polyacrylamide polymer particle; liquid retention aid Nuoerform860 is a water-soluble high molecular weight polyacrylamide derivative.

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