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CN-122013577-A - Preparation process of low-dust-content kraft pulp

CN122013577ACN 122013577 ACN122013577 ACN 122013577ACN-122013577-A

Abstract

The invention discloses a preparation process of low-dust-content kraft pulp, and belongs to the technical field of kraft pulp. The technical scheme includes that 1) pulp crushing and primary screening are carried out, fiber raw material waste paper enters a rotary drum pulper from a chain plate conveyor to screen out large impurities which are not crushed, 2) primary purification and flotation are carried out, the screened pulp enters a two-stage coarse screen through a two-stage high-concentration slag remover, the pulp enters a flotation impurity removing machine to screen out impurities which are more than 14mm through a cylindrical screen, 3) fiber classification is carried out, the pulp enters a classification screening to screen out short fibers, medium fibers and long fibers, and 4) short fiber treatment, medium fiber treatment and long fiber treatment are respectively carried out to obtain corresponding pulp. The invention realizes fiber grading and refining treatment, high-efficiency deep impurity removal and can obviously reduce the dust degree of the kraft liner board.

Inventors

  • ZHANG JIANLING
  • WANG JUNMING
  • WANG ZENGJIAN
  • QUAN JIPING

Assignees

  • 山东博汇纸业股份有限公司

Dates

Publication Date
20260512
Application Date
20260227

Claims (5)

  1. 1. The preparation process of the low-dust-content kraft pulp is characterized by comprising the following steps of: 1) Pulping and primary screening, namely, fibrous raw waste paper enters a rotary drum pulper from a chain plate conveyor, the front section of the rotary drum pulper is a pulping section, the pulping section accounts for 2/3 of the length of the rotary drum pulper, the concentration of pulp is 18-20%, the waste paper separated into fibers enters a screening section, the screening section accounts for 1/3 of the length of the rotary drum pulper, the concentration of pulp is 3.5-5.0%, and a screening section cylinder is provided with a sieve mesh with the aperture of 6-10mm, so that large impurities which are not crushed are screened; 2) Primary purification and flotation, namely, the screened slurry enters a two-stage coarse screen through a two-stage high-concentration slag remover, the slurry inlet concentration of the high-concentration slag remover is 2.0-4.0%, the slurry inlet pressure is 0.2-0.35MPa, the slurry inlet concentration of a coarse screen system is 2.0-3.5%, and the slurry inlet pressure is 0.15-0.25MPa; 3) The sizing agent enters a grading sieve, the grading sieve is divided into a first-stage grading sieve and a second-stage grading sieve, the first-stage grading sieve screens out short fibers, the size of a sieve gap is 0.15-0.20mm, the second-stage grading sieve screens out medium fibers and long fibers, the size of the sieve gap is 0.25-0.30mm, the medium fibers which can pass through the sieve gap can continuously rise, the medium fibers can not pass through the sieve gap enter the top of the second-stage grading sieve, and the long fibers are discharged as long fibers from a sizing pipe; 4) Short fiber treatment, namely, short fiber passes through a three-stage low-concentration slag remover, tailings are discharged, fine pulp enters a multi-disc thickener, and enters a pulp tower I after passing through a heat dispersing machine for being used for a core layer and a bottom layer; Medium fiber treatment, namely, medium fiber passes through a three-stage low-concentration slag remover, tailings are discharged, good pulp passes through a two-stage light-weight slag remover and then enters a multi-disc thickener, and then enters a pulp tower II through a heat dispersing machine for use in a surface layer and a bottom layer; Long fiber treatment, namely long fiber passes through a five-stage low-concentration slag remover, tailings are discharged, fine pulp enters a three-stage fine screen and then enters a multi-disc thickener, and then enters a pulp tower III through a thermal dispersion machine, pulp is ground through a pulp grinder, and enters a paper machine for core layers.
  2. 2. The process for preparing the low-dust kraft pulp according to claim 1, wherein in the step 4), the pulp inlet concentration of the short fiber one-stage low-concentration slag separator is 0.5-2.0%, the pulp inlet pressure is 0.16-0.25MPa, the pulp outlet pressure is 0.03-0.1MPa, the pulp inlet concentration of the two-stage low-concentration slag separator is 0.4-2.0%, the pulp inlet pressure is 0.16-0.25MPa, the pulp inlet pressure is 0.03-0.1MPa, the pulp inlet concentration of the three-stage low-concentration slag separator is 0.4-2.0%, the pulp inlet pressure is 0.16-0.25MPa, the pulp inlet pressure is 0.03-0.1MPa, the pulp outlet concentration is 10-12%, the temperature of the short fiber multi-disc thickener is 90-120 ℃, the inlet concentration of the press screw is 8-12%, the outlet concentration is 25-40%, and the torque is 25-40%.
  3. 3. The process for preparing the low-dust kraft pulp according to claim 1, wherein in the step 4), the pulp inlet concentration of the first-stage low-concentration slag separator of the medium fiber is 0.5-2.0%, the pulp inlet pressure is 0.16-0.25MPa, the pulp inlet pressure is 0.03-0.1MPa, the pulp inlet concentration of the second-stage low-concentration slag separator is 0.4-2.0%, the pulp inlet pressure is 0.16-0.25MPa, the pulp inlet pressure is 0.03-0.1MPa, the pulp inlet concentration of the third-stage low-concentration slag separator is 0.4-2.0%, the pulp inlet pressure is 0.16-0.25MPa, the pulp inlet pressure is 0.03-0.1MPa, the pulp inlet pressure of the first-stage light slag separator of the medium fiber is 0.4-2.0%, the pulp inlet pressure is 0.16-0.25MPa, the pulp inlet pressure of the second-stage light slag separator is 0.05-0.1MPa, the pulp inlet concentration of the medium fiber is 0.1-1.5%, the pulp inlet pressure of the pulp inlet of the medium fiber is 0.15-0.05-0.5%, the pulp inlet of the high-concentration kraft pulp is 0.40% of the disc press is 0.5-12%, and the temperature of the medium fiber is 0.40% of the high-concentration of the high-pressure is 12% of the disc press machine is 0.12%.
  4. 4. The process for preparing the low-dust kraft pulp according to claim 3, wherein when the pulp entering the second pulp tower in the step 4) is applied to the surface layer, the medium-fiber pulp is subjected to the following process treatment of coarse screening, a low-concentration slag separator, fine screening, a multi-disc thickener and a surface layer pulping tower, wherein the screen gap in the coarse screening process is 0.45-0.55mm, the pulp inlet pressure is 0.25-0.35bar, the pulp inlet concentration of the low-concentration slag separator is 0.9%, the pulp inlet pressure is 0.2-0.3bar, the screen gap in the fine screening process is 0.15mm, the pulp inlet pressure is 0.25-0.35bar, and the pulp inlet concentration in the multi-disc thickener is 0.5-1.0%.
  5. 5. The process for preparing the low-dust kraft pulp according to claim 1, wherein in the step 4), the pulp inlet concentration of the first-stage low-concentration slag separator of the long fiber is 1.0-2.5%, the pulp inlet pressure is 0.25-0.4 MPa%, the pulp inlet pressure is 0.12-0.22 MPa%, the pulp inlet concentration of the second-stage low-concentration slag separator is 1.0-2.5%, the pulp inlet pressure is 0.15-0.25MPa, the pulp inlet pressure is 0.03-0.15MPa, the pulp inlet concentration of the third-stage low-concentration slag separator is 0.5-2.0%, the pulp inlet pressure is 0.15-0. 0.25 MPa%, the pulp inlet pressure is 0.03-0.15MPa, the pulp inlet concentration of the long fiber four-stage low-concentration slag separator is 0.5-2.0.0 MPa, the pulp inlet pressure is 0.15-0.25MPa, the pulp inlet pressure is 0.02-0.1MPa, the pulp inlet concentration of the five-stage low-concentration slag separator is 0.5-2.0.0 MPa, the pulp inlet pressure is 0.15-0.25MPa, the pulp inlet pressure is 0.25-0.25% and the pulp inlet pressure is 0.14-0.5-2.40%, the pulp inlet concentration of the long fiber is 0.1-1.25% of the high-concentration disc is 0.6% of the high-concentration pulp, the pulp inlet pressure is 0.25-0.25% and the pulp inlet pressure is 0.6.25% and the pulp inlet pressure is 0.6% of the fine fiber is 0.6-0.25% and the high-6% of the fine fiber is 0.8% of the fine fiber is high-concentration sieve is high.

Description

Preparation process of low-dust-content kraft pulp Technical Field The invention belongs to the technical field of kraft paper, and particularly relates to a preparation process of low-dust-content kraft paper pulp. Background The kraft paper is used as a high-strength packaging paper, and has high requirements on physical strength (such as ring crush strength and bursting strength) and cleanliness. Along with the gradual increase of the market demand for craft paper products with high paper surface cleanliness, the craft paper raw materials required by products such as high-grade cigarette and wine packing boxes, electronic product packing boxes and the like require higher cleanliness, and the dust degree is taken as an important measurement index of the cleanliness, so that the cleanliness of the paper surface can be reflected to a certain extent. However, the main body of the kraft paper production raw material is recycled cardboard waste paper, office waste paper and other secondary fibers (OCC), and the secondary fiber raw material contains a large amount of impurities such as printing ink, coating films, coating particles, colloidal particles, gravel and the like, and fiber bundles, coating white spots, dust, wax spots and the like which cannot be dyed exist, so that the cleanliness of the kraft paper surface is seriously affected. In the existing craft paper production, a process route of 'crushing-coarse screening- (direct) deslagging' is generally adopted for OCC sizing agent, and the working environment of a heavy slag remover is complex and the efficiency is low because of extremely large difference of fiber length and morphology in the sizing agent which is not classified, and the technical scheme is characterized in that a long fiber is easy to wind and shade tiny heavy impurities, so that the long fiber is difficult to be effectively centrifugally separated; b, the mass ratio difference of fibers with different lengths and impurities is large, the removal of all impurities is difficult to achieve under the condition of fixed deslagging parameters, deslagging is incomplete, and the improvement of paper cleanliness is a bottleneck; and c, improving the deslagging strength or the deslagging frequency for pursuing the cleaning, and increasing the loss of the good pulp fiber and the energy consumption. Therefore, developing a craft paper slurry preparation process capable of realizing fiber grading and refining treatment, high-efficiency deep impurity removal and remarkably reducing paper dust degree becomes a problem to be solved in the field. Disclosure of Invention The invention provides a preparation process of low-dust-content kraft pulp, which realizes fiber grading and refining treatment, high-efficiency deep impurity removal and can obviously reduce the dust content of kraft. The technical scheme of the invention is as follows: The preparation process of the low-dust-degree kraft pulp comprises the following steps of: 1) Pulping and primary screening, namely, fibrous raw waste paper enters a rotary drum pulper from a chain plate conveyor, the front section of the rotary drum pulper is a pulping section, the pulping section accounts for 2/3 of the length of the rotary drum pulper, the concentration of pulp is 18-20%, the waste paper separated into fibers enters a screening section, the screening section accounts for 1/3 of the length of the rotary drum pulper, the concentration of pulp is 3.5-5.0%, and a screening section cylinder is provided with a sieve mesh with the aperture of 6-10mm, so that large impurities which are not crushed are screened; 2) Primary purification and flotation, namely, the screened pulp enters a two-stage coarse screen through a two-stage high-concentration slag remover, the pulp inlet concentration of the high-concentration slag remover is 2.0-4.0%, the pulp inlet pressure is 0.2-0.35MPa, the pulp inlet concentration of a coarse screen system is 2.0-3.5%, and the pulp inlet pressure is 0.15-0.25MPa; 3) The sizing agent enters a grading sieve, the grading sieve is divided into a first-stage grading sieve and a second-stage grading sieve, the first-stage grading sieve screens out short fibers, the size of a sieve gap is 0.15-0.20mm, the second-stage grading sieve screens out medium fibers and long fibers, the size of the sieve gap is 0.25-0.30mm, the medium fibers which can pass through the sieve gap can continuously rise, the medium fibers can not pass through the sieve gap enter the top of the second-stage grading sieve, and the long fibers are discharged as long fibers from a sizing pipe; 4) Short fiber treatment, namely, short fiber passes through a three-stage low-concentration slag remover, tailings are discharged, fine pulp enters a multi-disc thickener, and enters a pulp tower I after passing through a heat dispersing machine for being used for a core layer and a bottom layer; Medium fiber treatment, namely, medium fiber passes through a three-stage low-conce