CN117867886A - Production process of cotton pulp for lithium battery-grade cellulose ether - Google Patents
Production process of cotton pulp for lithium battery-grade cellulose ether Download PDFInfo
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- CN117867886A CN117867886A CN202410151246.2A CN202410151246A CN117867886A CN 117867886 A CN117867886 A CN 117867886A CN 202410151246 A CN202410151246 A CN 202410151246A CN 117867886 A CN117867886 A CN 117867886A
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- 229920000742 Cotton Polymers 0.000 title claims abstract description 133
- 229920003086 cellulose ether Polymers 0.000 title claims abstract description 54
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 53
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 53
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 claims abstract description 125
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 66
- 238000004537 pulping Methods 0.000 claims abstract description 62
- 239000003513 alkali Substances 0.000 claims abstract description 57
- 108090000790 Enzymes Proteins 0.000 claims abstract description 43
- 102000004190 Enzymes Human genes 0.000 claims abstract description 43
- 238000010306 acid treatment Methods 0.000 claims abstract description 38
- 238000002360 preparation method Methods 0.000 claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 23
- 239000012535 impurity Substances 0.000 claims abstract description 21
- 239000004576 sand Substances 0.000 claims abstract description 16
- 238000004061 bleaching Methods 0.000 claims abstract description 14
- 238000000746 purification Methods 0.000 claims abstract description 14
- 238000007598 dipping method Methods 0.000 claims abstract description 7
- 239000002002 slurry Substances 0.000 claims description 64
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 48
- 238000010025 steaming Methods 0.000 claims description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 238000009897 hydrogen peroxide bleaching Methods 0.000 claims description 24
- 239000008367 deionised water Substances 0.000 claims description 23
- 229910021641 deionized water Inorganic materials 0.000 claims description 23
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 20
- 238000005406 washing Methods 0.000 claims description 17
- QPCDCPDFJACHGM-UHFFFAOYSA-N N,N-bis{2-[bis(carboxymethyl)amino]ethyl}glycine Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(=O)O)CCN(CC(O)=O)CC(O)=O QPCDCPDFJACHGM-UHFFFAOYSA-N 0.000 claims description 16
- 238000002156 mixing Methods 0.000 claims description 16
- 229960003330 pentetic acid Drugs 0.000 claims description 16
- 238000007670 refining Methods 0.000 claims description 14
- 239000004094 surface-active agent Substances 0.000 claims description 12
- 101710121765 Endo-1,4-beta-xylanase Proteins 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 10
- 239000011347 resin Substances 0.000 claims description 10
- 229920005989 resin Polymers 0.000 claims description 10
- 229910019142 PO4 Inorganic materials 0.000 claims description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 9
- 239000010452 phosphate Substances 0.000 claims description 9
- 229940051841 polyoxyethylene ether Drugs 0.000 claims description 9
- 229920000056 polyoxyethylene ether Polymers 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 8
- 150000002191 fatty alcohols Chemical class 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
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- 238000012546 transfer Methods 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 7
- 238000007865 diluting Methods 0.000 claims description 5
- 108010059820 Polygalacturonase Proteins 0.000 claims description 3
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- 238000009835 boiling Methods 0.000 claims 1
- 239000000428 dust Substances 0.000 abstract description 15
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- 239000000835 fiber Substances 0.000 abstract description 3
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 22
- 238000010009 beating Methods 0.000 description 7
- 238000006555 catalytic reaction Methods 0.000 description 7
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- TUJKJAMUKRIRHC-UHFFFAOYSA-N hydroxyl Chemical compound [OH] TUJKJAMUKRIRHC-UHFFFAOYSA-N 0.000 description 2
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- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001814 pectin Substances 0.000 description 2
- 229920001277 pectin Polymers 0.000 description 2
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- 239000000126 substance Substances 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
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- 239000001913 cellulose Substances 0.000 description 1
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- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- LPUQAYUQRXPFSQ-DFWYDOINSA-M monosodium L-glutamate Chemical compound [Na+].[O-]C(=O)[C@@H](N)CCC(O)=O LPUQAYUQRXPFSQ-DFWYDOINSA-M 0.000 description 1
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Abstract
The invention provides a production process of cotton pulp for lithium battery-grade cellulose ether, and relates to the technical field of cotton pulp. The production process comprises the following steps: 1) Selecting materials, opening cotton and removing impurities by a dry method; 2) Enzyme-assisted wet purification; 3) A continuous electrocatalytic process; 4) Alkali preparation, dipping and stewing; 5) A front sand removal process; 6) A pre-pulping process; 7) A concentration step; 8) Bleaching with hydrogen peroxide; 9) An acid treatment step; 10 A post-desanding process; 11 A post-pulping process; 12 A pulp making process. By using the enzyme-assisted wet purification technology and the electrocatalytic reaction technology, the lithium battery-grade fiber is not only remarkably improvedThe quality of the cellulose ether ensures that the content of the prepared cotton pulp poly-alpha cellulose is more than or equal to 97 percent and the small dust is less than or equal to 200mm 2 And/kg, the COD discharge amount of the wastewater in the whole production process is 7000-10000 mg/L, and the sewage treatment pressure is greatly reduced.
Description
Technical Field
The invention relates to the technical field of cotton pulp, in particular to a production process of cotton pulp for lithium battery-grade cellulose ether.
Background
Cellulose ether is a generic name of various derivatives obtained by etherification of natural cellulose, and is widely applied to industries such as lithium batteries, medicine and health, daily chemical industry, papermaking, foods, buildings, materials, petroleum drilling and the like, and commonly called as industrial monosodium glutamate. The lithium battery grade cellulose ether is a high-end product in cellulose ether, and the higher the purity, the lower the dust, and the better the product quality. The product quality of the lithium battery grade cellulose ether is mainly determined by the purity of the fiber raw material, the higher the purity of the fiber raw material is, the lower the dust is, the lower the metal ion content is, and the better the product quality of the prepared lithium battery grade cellulose ether is.
The cotton pulp for the lithium battery-grade cellulose ether solves the problems of high purity and low dust most difficultly, and influences the production and the use of the lithium battery-grade cellulose ether. The traditional cotton pulp production generally adopts a high-temperature and high-alkali cooking mode, so that the high purity and low dust of cotton pulp are difficult to ensure; meanwhile, a large amount of black liquor is generated in the cooking process, and the black liquor has the characteristics of high alkali concentration, deep color, high organic matter content and poor biodegradability, and is industrial wastewater with high pollution load and difficult treatment.
Therefore, how to reduce the generation of black liquor while preparing high-purity, low-dust lithium battery-grade cellulose ether cotton pulp is a technical problem that needs to be solved by the person skilled in the art.
Disclosure of Invention
Aiming at the defects of the prior art, the invention designs a production method of cotton pulp for lithium battery-grade cellulose ether, which uses an enzyme-assisted wet purification technology and an electrocatalytic reaction technology to ensure that the content of the prepared cotton pulp poly-alpha cellulose is more than or equal to 97 percent,small dust less than or equal to 200mm 2 And (3) the substitution degree of the lithium battery-grade cellulose ether is uniform, the viscosity is stable, the compatibility is good, the quality of the lithium battery-grade cellulose ether is improved, the COD discharge amount of wastewater in the whole production process is 7000-10000 mg/L, and the sewage treatment pressure is greatly reduced.
In order to achieve the above object, the present invention provides the following technical solutions:
a production process of cotton pulp for lithium battery-grade cellulose ether comprises the following steps: 1) Selecting materials, opening cotton and removing impurities by a dry method; 2) Enzyme-assisted wet purification; 3) A continuous electrocatalytic process; 4) Alkali preparation, dipping and stewing; 5) A front sand removal process; 6) A pre-pulping process; 7) A concentration step; 8) Bleaching with hydrogen peroxide; 9) An acid treatment step; 10 A post-desanding process; 11 A post-pulping process; 12 A pulp making process.
Preferably, the step 1) comprises the steps of selecting materials, opening cotton and removing impurities by a dry method: three types of first-grade cotton linters with the maturity of more than or equal to 80 percent are selected, and after tearing the cotton linters by a cotton opener, the selected cotton linters are obtained through loosening and impurity removal.
Preferably, the step 2) enzyme-assisted wet purification process comprises the following steps: mixing the carefully selected cotton linters with the black liquor to make the concentration of the carefully selected cotton linters in the system be 5% and the pH value of the system be 4-6, and then adding a mixed enzyme preparation for enzymolysis.
Preferably, the black liquor is black liquor generated in the cooking process of step 4) in the production process of the cotton pulp for the lithium battery grade cellulose ether, and water is added when the cotton pulp for the lithium battery grade cellulose ether is produced for the first time.
Preferably, the mixed enzyme preparation comprises surfactant fatty alcohol polyoxyethylene ether phosphate, pectinase, xylanase and resin control enzyme; the dosage of the surfactant fatty alcohol polyoxyethylene ether phosphate is 0.5-1 kg/ton, the dosage of the pectase is 0.5-1 kg/ton, the dosage of the xylanase is 0.5-1 kg/ton and the dosage of the resin control enzyme is 0.5-1 kg/ton; the enzymolysis time is 60min.
Preferably, the step 3) of continuous electrocatalytic process comprises: adding hydrogen peroxide into the selected cotton linters after enzymolysis and performing electrocatalysis, wherein the electrocatalysis time is 20-30 min, the temperature is 60-70 ℃, and the dosage of the hydrogen peroxide is 1.0-2.0% of the mass of absolute dry pulp.
Preferably, the alkali preparation procedure in the step 4) is as follows: alkali is prepared at 80-85 ℃, the total alkali is 6-10% of the absolute dry pulp mass calculated by NaOH, and Na is used as the alkali 2 SO 3 0.4 to 0.8 percent of the mass of the absolute dry pulp; naOH was formulated as 40g/L lye and Na was added 2 SO 3 Adding into alkali liquor to obtain the prepared alkali liquor.
Preferably, the dipping procedure is as follows: and (3) pumping the prepared alkali liquor into a rotary spherical digester, and fully mixing the alkali liquor with the electrocatalytic cotton linters through cold transfer.
Preferably, the steaming process comprises the following steps: heating and steaming the materials in the steaming ball, wherein the steaming temperature is 120-135 ℃ and the steaming time is 120min.
Preferably, the step 5) of the preceding sand removal step comprises: and (3) putting the steamed slurry into a desanding machine for desanding, wherein the pressure is 0.30-0.32 Mpa, the concentration of the slurry is 0.4-0.6%, and the desanding rate is 10-30 min/t.
Preferably, the pre-pulping process of the step 6) is as follows: transferring the degritted slurry into a first large taper refiner for pre-pulping, wherein the pulping current is 180-200A, and the slurry concentration is 1.0% -1.8%; the beating speed is 10-30 min/t.
Preferably, the concentrating step of the step 7) is as follows: and (3) transferring the pulp subjected to the pre-pulping into a side pressure cylinder thickener for concentration, wherein the pulp concentration is 10% -12%.
Preferably, the hydrogen peroxide bleaching process in the step 8) comprises the following steps: transferring the concentrated slurry into a medium concentration mixer, adding diethylenetriamine pentaacetic acid and hydrogen peroxide, introducing steam, mixing at 90-110 ℃ for 20-30 min, and transferring into a hydrogen peroxide bleaching tower; wherein, the dosage of the diethylenetriamine pentaacetic acid is 0.17 to 0.22 percent of the mass of the absolute dry pulp, and the dosage of the hydrogen peroxide is 2.2 to 2.8 percent of the mass of the absolute dry pulp.
Preferably, bleaching reaction is carried out in a hydrogen peroxide bleaching tower at 90-110 ℃ for 100-120 min, deionized water is used for dilution after bleaching to make the pulp concentration be 1-1.5%, then the pulp is sent to a vacuum pulp washer for washing to be neutral, and the pulp is sent to an acid treatment tower after washing
Preferably, the acid treatment step of the step 9) comprises the following steps: adding hydrochloric acid with the relative absolute dry pulp amount of 2-2.5% for acid treatment, wherein the acid treatment time is 20-40 min, and then washing with deionized water for 2-3 hours; the concentration of the hydrochloric acid is 350g/L.
Preferably, the post-sand removal procedure of the step 10) is as follows: and (3) transferring the slurry subjected to acid treatment into a post-desanding machine, wherein the pressure of post-desanding is more than or equal to 0.3Mpa, the concentration of the slurry is 0.5% -0.7%, the desanding rate is 10-30 min/t, and transferring the slurry into a second large-taper refiner after desanding.
Preferably, the post-pulping process of the step 11) is as follows: and (3) transferring the pulp subjected to the sand removal into a second large taper refiner for post-pulping, wherein the pulping current is 160-180A, the pulp concentration is 2.5-2.7%, the pulping speed is 10-30 min/t, and transferring into a pulp making machine after refining.
Preferably, in the pulp making process of the step 12), the pulp concentration on the long wire of the pulp making machine is 8-12 g/L, the pressure of the drying cylinder is less than or equal to 0.20Mpa and is not 0, and the finished product is obtained after pulp making is completed.
Compared with the prior art, the invention has the following advantages and technical effects:
1. according to the invention, the enzyme-assisted dry-wet purification technology is utilized to remove impurities from cotton linters, so that the stewing conditions of a stewing process are reduced, and the COD of sewage is further reduced. The dry impurity removing system is used for removing impurities in an air medium state through a cotton opener, a multi-roller loosening machine, a heavy slag remover and a cyclone separator by utilizing the difference of specific gravities of cotton linters, cotton seed hulls, broken cotton stalks and dust; the enzyme-assisted wet purification process aims to soak cotton linters through the black liquor, and then remove impurities in the cotton linters further through centrifugal deslagging and concentration. According to the hydrophilic-lipophilic balance value (HLB value) of wax, the formula of the surfactant is optimized, the surfactant is added into the wet impurity removal process, the surfactant is utilized to emulsify fat and wax in cotton linters, so that the cotton linters become oil-in-water (O/W) emulsion which is dissolved into water, pectinase, xylanase and resin are synchronously added to control enzyme to decompose pectin, fat and wax in the cotton linters, so that the pectin, fat and wax content in the cotton linters is reduced, and the impurity removal rate of the cotton linters before cooking is more than 80%.
2. The invention utilizes the electrocatalytic reaction technology to cook the cotton linters, thereby improving the purity of cotton pulp and reducing the dust of the cotton pulp. The method adopts an electrocatalytic method, utilizes the characteristic of higher oxidation potential of hydroxyl radical active oxygen to oxidize colored groups in cotton linters, utilizes hydroxyl radical active oxygen to boil and float the cotton linters after impurity removal, and all the remaining tiny impurities are dissolved to form pale yellow pulping residual liquid, so that pulping black liquid which is difficult to treat does not appear, reaction conditions of a steaming process can be reduced, consumption of chemical medicines is reduced, and generation of black liquid is reduced. Therefore, the COD discharge amount of the wastewater in the whole pulping process is less than 10000mg/L, and the sewage treatment pressure is reduced.
Detailed Description
Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the invention described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present invention. The specification and examples are exemplary only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.
The "room temperature" and "normal temperature" in the present invention are all calculated at 25.+ -. 2 ℃ unless otherwise specified.
The raw materials used in the following examples of the present invention are all commercially available.
Example 1
A production process of high-purity and low-dust cotton pulp for lithium battery-grade cellulose ether comprises the following steps:
1) Selecting materials, opening cotton, and removing impurities by a dry method. Three types of first-grade cotton linters with the maturity of more than or equal to 80 percent are selected, and are loosened and decontaminated by a multi-roller loosening machine and a heavy slag remover respectively after being torn by a cotton opener, and then are transferred into a cotton extruder and are sent to an enzyme-assisted wet purification process by a cyclone separator.
2) Enzyme assisted wet clean up procedure. Mixing the carefully selected cotton linters with the black liquor, enabling the concentration of the carefully selected cotton linters in a system to be 5%, enabling the pH value of the system to be 6, adding a mixed enzyme preparation for enzymolysis for 60min, and conveying the mixture to the next working procedure through a screw after the enzymolysis is finished (the dosage of surfactant fatty alcohol polyoxyethylene ether phosphate in the mixed enzyme preparation is 0.5 kg/ton, the dosage of pectase is 1 kg/ton, the dosage of xylanase is 0.8 kg/ton, and the dosage of resin control enzyme is 0.9 kg/ton).
3) And (3) a continuous electrocatalytic process. And adding hydrogen peroxide into the selected cotton linters after enzymolysis and performing electrocatalysis, wherein the electrocatalysis time is 20min, the temperature is 70 ℃, and the consumption of the hydrogen peroxide is 1.0% of the mass of the absolute dry pulp.
4) Alkali preparation, soaking and stewing. The alkali compounding temperature is controlled at 80 ℃, the total alkali is 6 percent relative to the weight of absolute dry pulp calculated by NaOH, and Na 2 SO 3 0.4% of the weight of the relative absolute dry pulp; naOH was formulated as 40g/L lye and Na was added 2 SO 3 Adding the mixed solution into alkali liquor to obtain prepared alkali liquor; then the prepared alkali liquor is injected into a rotary spherical digester and fully mixed with the cotton linters which are loaded into the rotary spherical digester and subjected to electric catalysis through cold transfer for impregnation; then heating and steaming the materials in the steaming ball, wherein the steaming temperature is 135 ℃, the steaming time is 120min, and the next procedure is carried out after the steaming is completed.
5) And (5) a front sand removal process. And (3) putting the steamed slurry into a desanding machine for desanding, wherein the pressure is controlled to be 0.30Mpa, the concentration of the slurry is controlled to be 0.4%, and the desanding rate is 15min/t.
6) And (5) a pre-pulping process. Transferring the degritted slurry into a first large taper refiner for pre-pulping, wherein the pulping current is controlled at 180A, and the slurry concentration is controlled at 1.0%; the beating rate was 15min/t.
7) And (3) a concentration step. And (3) transferring the pulp after the front pulping into a side pressure cylinder thickener for concentration, wherein the pulp concentration is controlled at 10%.
8) And (3) a hydrogen peroxide bleaching process.
a: transferring the concentrated slurry into a medium concentration mixer, adding diethylenetriamine pentaacetic acid and hydrogen peroxide, introducing steam, mixing at 90 ℃ for 30min, and transferring into a hydrogen peroxide bleaching tower; wherein, the dosage of the diethylenetriamine pentaacetic acid is 0.17% of the mass of the absolute dry pulp, and the dosage of the hydrogen peroxide is 2.2% of the mass of the absolute dry pulp;
b: bleaching reaction is carried out in a hydrogen peroxide bleaching tower at 90 ℃ for 120min, deionized water is used for dilution after bleaching is finished to make the concentration of pulp be 1%, and then the pulp is sent to a vacuum pulp washer to be washed to be neutral by the deionized water, and the pulp enters an acid treatment tower after washing.
9) And (3) an acid treatment procedure. Adding hydrochloric acid (concentration 350 g/L) with the relative absolute dry pulp amount of 2% for acid treatment, wherein the acid treatment time is 30min, washing with deionized water for 2.5 hours, and transferring into a post-desander.
10 Post-desanding procedure: and (3) transferring the slurry subjected to acid treatment into a post-desanding machine, wherein the pressure of post-desanding is controlled at 0.3Mpa, the concentration of the slurry is controlled at 0.5%, the desanding rate is 30min/t, and transferring the slurry into a second large-taper refiner after desanding.
11 Post-pulping process: the current control of the second large taper refining machine is 160A, the pulp concentration is controlled to be 2.5%, the pulping speed is 15min/t, and the pulp is transferred into a pulp making machine after refining.
12 Pulp making process: the pulp concentration on the long wire of the pulp machine is controlled at 8g/L, the pressure of a drying cylinder is 0.15Mpa, and the finished product of cotton pulp for the lithium battery-grade cellulose ether is prepared after pulp making is completed.
The lithium battery grade cellulose ether prepared in example 1 was tested with a cotton pulp finished product, and specific indexes of the product are shown in table 1:
table 1 example 1 detection index of cotton pulp for lithium battery grade cellulose ether
Example 2
A production process of high-purity and low-dust cotton pulp for lithium battery-grade cellulose ether comprises the following steps:
1) Selecting materials, opening cotton, and removing impurities by a dry method. Three types of first-grade cotton linters with the maturity of more than or equal to 80 percent are selected, and are loosened and decontaminated by a multi-roller loosening machine and a heavy slag remover respectively after being torn by a cotton opener, and then are transferred into a cotton extruder and are sent to spiral squeezing and dipping by a cyclone separator.
2) Enzyme assisted wet clean up procedure. Mixing the carefully selected cotton linters with the black liquor, enabling the concentration of the carefully selected cotton linters in a system to be 5%, enabling the pH value of the system to be 6, adding a mixed enzyme preparation for enzymolysis for 60min, and conveying the mixture to the next working procedure through a screw after the enzymolysis is finished (the dosage of surfactant fatty alcohol polyoxyethylene ether phosphate in the mixed enzyme preparation is 1 kg/ton, the dosage of pectase is 0.7 kg/ton, the dosage of xylanase is 0.6 kg/ton, and the dosage of resin control enzyme is 0.5 kg/ton).
3) And (3) a continuous electrocatalytic process. And adding hydrogen peroxide into the selected cotton linters after enzymolysis and performing electrocatalysis, wherein the electrocatalysis time is 20min, the temperature is 70 ℃, and the consumption of the hydrogen peroxide is 2.0% of the mass of the absolute dry pulp.
4) Alkali preparation, soaking and stewing. The alkali compounding temperature is controlled at 85 ℃, the total alkali is 10 percent relative to the weight of absolute dry pulp calculated by NaOH, and Na 2 SO 3 0.8% relative to the weight of the oven dried pulp; naOH was formulated as 40g/L lye and Na was added 2 SO 3 Adding the mixed solution into alkali liquor to obtain prepared alkali liquor; then the prepared alkali liquor is injected into a rotary spherical digester and fully mixed with the cotton linters which are loaded into the rotary spherical digester and subjected to electric catalysis through cold transfer for impregnation; then heating and steaming the materials in the steaming ball, wherein the steaming temperature is 120 ℃, the steaming time is 120min, and the next procedure is carried out after the steaming is completed.
5) And (5) a front sand removal process. And (3) putting the steamed slurry into a desanding machine for desanding, wherein the pressure is controlled to be 0.32Mpa, the concentration of the slurry is controlled to be 0.6%, and the desanding rate is 30min/t.
6) And (5) a pre-pulping process. Transferring the degritted slurry into a first large taper refiner for pre-pulping, wherein the pulping current is controlled at 200A, and the slurry concentration is controlled at 1.8%; the beating rate was 25min/t.
7) And (3) a concentration step. And (3) transferring the pulp after the front pulping into a side pressure cylinder thickener for concentration, wherein the pulp concentration is controlled at 10%.
8) And (3) a hydrogen peroxide bleaching process.
a: transferring the concentrated slurry into a medium concentration mixer, adding diethylenetriamine pentaacetic acid and hydrogen peroxide, introducing steam, mixing at 110 ℃ for 20min, and transferring into a hydrogen peroxide bleaching tower; wherein, the dosage of the diethylenetriamine pentaacetic acid is 0.22% of the mass of the absolute dry pulp, and the dosage of the hydrogen peroxide is 2.8% of the mass of the absolute dry pulp;
b: bleaching in hydrogen peroxide bleaching tower at 110 deg.c for 100min, diluting with deionized water to reach pulp concentration of 1%, washing with deionized water to neutrality, and acid treating in acid treating tower.
9) And (3) an acid treatment procedure. Hydrochloric acid (350 g/L) with the relative absolute dry pulp content of 2.5% is added for acid treatment, the acid treatment time is 40min, deionized water is used for washing for 3 hours, and then the mixture is transferred into a post-desander.
10 Post-desanding procedure: and (3) transferring the slurry subjected to acid treatment into a post-desanding machine, wherein the pressure of post-desanding is controlled at 0.5Mpa, the concentration of the slurry is controlled at 0.7%, the desanding rate is 20min/t, and transferring the slurry into a second large-taper refiner after desanding.
11 Post-pulping process: the current control of the second large taper refining machine is 180A, the pulp concentration is controlled to be 2.7%, the pulping speed is 30min/t, and the pulp is transferred into a pulp making machine after refining.
12 Pulp making process: the pulp concentration on the long wire of the pulp machine is controlled at 12g/L, the pressure of a drying cylinder is 0.20Mpa, and the finished product of cotton pulp for the lithium battery-grade cellulose ether is prepared after pulp making is completed.
The lithium battery grade cellulose ether prepared in example 2 was tested with a cotton pulp finished product, and specific indexes of the product are shown in table 2:
table 2 example 2 cotton pulp detection index for lithium battery grade cellulose ether
Example 3
A production process of high-purity and low-dust cotton pulp for lithium battery-grade cellulose ether comprises the following steps:
1) Selecting materials, opening cotton, and removing impurities by a dry method. Three types of first-grade cotton linters with the maturity of more than or equal to 80 percent are selected, and are loosened and decontaminated by a multi-roller loosening machine and a heavy slag remover respectively after being torn by a cotton opener, and then are transferred into a cotton extruder and are sent to an enzyme-assisted wet purification process by a cyclone separator.
2) Enzyme assisted wet clean up procedure. Mixing the carefully selected cotton linters with the black liquor, enabling the concentration of the carefully selected cotton linters in a system to be 5%, enabling the pH value of the system to be 5, adding a mixed enzyme preparation for enzymolysis for 60min, and conveying the mixture to the next working procedure through a screw after the enzymolysis is finished (the dosage of surfactant fatty alcohol polyoxyethylene ether phosphate in the mixed enzyme preparation is 0.9 kg/ton, the dosage of pectase is 0.5 kg/ton, the dosage of xylanase is 1 kg/ton, and the dosage of resin control enzyme is 0.7 kg/ton).
3) And (3) a continuous electrocatalytic process. And adding hydrogen peroxide into the selected cotton linters after enzymolysis and performing electric catalysis, wherein the electric catalysis time is 25min, the temperature is 65 ℃, and the consumption of the hydrogen peroxide is 1.5 percent of the mass of the relative absolute dry pulp.
4) Alkali preparation, soaking and stewing. The alkali compounding temperature is controlled at 80 ℃, the total alkali is 8 percent relative to the weight of absolute dry pulp calculated by NaOH, and Na 2 SO 3 0.6% relative to the weight of the oven dried pulp; naOH was formulated as 40g/L lye and Na was added 2 SO 3 Adding the mixed solution into alkali liquor to obtain prepared alkali liquor; then the prepared alkali liquor is injected into a rotary spherical digester and fully mixed with the cotton linters which are loaded into the rotary spherical digester and subjected to electric catalysis through cold transfer for impregnation; then heating and steaming the materials in the steaming ball, wherein the steaming temperature is 125 ℃, the steaming time is 120min, and the next procedure is carried out after the steaming is completed.
5) And (5) a front sand removal process. And (3) putting the steamed slurry into a desanding machine for desanding, wherein the pressure is controlled to be 0.31Mpa, the concentration of the slurry is controlled to be 0.5%, and the desanding rate is 25min/t.
6) And (5) a pre-pulping process. Transferring the degritted slurry into a first large taper refiner for pre-pulping, wherein the pulping current is controlled at 190A, and the slurry concentration is controlled at 1.4%; the beating rate was 25min/t.
7) And (3) a concentration step. And (3) transferring the pulp after the front pulping into a side pressure cylinder thickener for concentration, wherein the pulp concentration is controlled at 11%.
8) And (3) a hydrogen peroxide bleaching process.
a: transferring the concentrated slurry into a medium concentration mixer, adding diethylenetriamine pentaacetic acid and hydrogen peroxide, introducing steam, mixing at 110 ℃ for 25min, and transferring into a hydrogen peroxide bleaching tower; wherein, the dosage of the diethylenetriamine pentaacetic acid is 0.20% of the mass of the absolute dry pulp, and the dosage of the hydrogen peroxide is 2.5% of the mass of the absolute dry pulp;
b: bleaching reaction is carried out in a hydrogen peroxide bleaching tower at the reaction temperature of 100 ℃ for 110min, deionized water is used for dilution after bleaching is finished to make the pulp concentration be 1.2%, then the pulp is sent to a vacuum pulp washer to be washed to be neutral by the deionized water, and the pulp enters an acid treatment tower after washing.
9) And (3) an acid treatment procedure. Hydrochloric acid (with the concentration of 350 g/L) with the relative absolute dry pulp amount of 2.2% is added for acid treatment, the acid treatment time is 30min, deionized water is used for washing for 2.5 hours, and then the mixture is transferred into a post sand remover.
10 Post-desanding procedure: and (3) transferring the slurry subjected to acid treatment into a post-desanding machine, wherein the pressure of post-desanding is controlled at 0.4Mpa, the concentration of the slurry is controlled at 0.6%, the desanding rate is 20min/t, and transferring the slurry into a second large-taper refiner after desanding.
11 Post-pulping process: the current control of the second large taper refining machine is 170A, the pulp concentration is controlled to be 2.6%, the pulping speed is 20min/t, and the pulp is transferred into a pulp making machine after refining.
12 Pulp making process: the pulp concentration on the long wire of the pulp machine is controlled at 10g/L, the pressure of a drying cylinder is 0.15Mpa, and the finished product of cotton pulp for the lithium battery-grade cellulose ether is prepared after pulp making is completed.
The lithium battery grade cellulose ether prepared in example 3 was tested with a cotton pulp finished product, and specific indexes of the product are shown in table 3:
table 3 example 3 detection index of cotton pulp for lithium cell grade cellulose ether
Example 4
A production process of high-purity and low-dust cotton pulp for lithium battery-grade cellulose ether comprises the following steps:
1) Selecting materials, opening cotton, and removing impurities by a dry method. Three types of first-grade cotton linters with the maturity of more than or equal to 80 percent are selected, and are loosened and decontaminated by a multi-roller loosening machine and a heavy slag remover respectively after being torn by a cotton opener, and then are transferred into a cotton extruder and are sent to an enzyme-assisted wet purification process by a cyclone separator.
2) Enzyme assisted wet clean up procedure. Mixing the carefully selected cotton linters with the black liquor, enabling the concentration of the carefully selected cotton linters in a system to be 5%, enabling the pH value of the system to be 6, adding a mixed enzyme preparation for enzymolysis for 60min, and conveying the mixture to the next working procedure through a screw after the enzymolysis is finished (the dosage of surfactant fatty alcohol polyoxyethylene ether phosphate in the mixed enzyme preparation is 0.5 kg/ton, the dosage of pectase is 0.5 kg/ton, the dosage of xylanase is 0.5 kg/ton, and the dosage of resin control enzyme is 0.5 kg/ton).
3) And (3) a continuous electrocatalytic process. And adding hydrogen peroxide into the selected cotton linters after enzymolysis and performing electrocatalysis, wherein the electrocatalysis time is 30min, the temperature is 60 ℃, and the consumption of the hydrogen peroxide is 1.5 percent of the mass of the absolute dry pulp.
4) Alkali preparation, soaking and stewing. The alkali compounding temperature is controlled at 80 ℃, the total alkali is 6 percent relative to the weight of absolute dry pulp calculated by NaOH, and Na 2 SO 3 0.4% of the weight of the relative absolute dry pulp; naOH was formulated as 40g/L lye and Na was added 2 SO 3 Adding the mixed solution into alkali liquor to obtain prepared alkali liquor; then the prepared alkali liquor is injected into a rotary spherical digester and fully mixed with the cotton linters which are loaded into the rotary spherical digester and subjected to electric catalysis through cold transfer for impregnation; then heating and steaming the materials in the steaming ball, wherein the steaming temperature is 120 ℃, the steaming time is 120min, and the next procedure is carried out after the steaming is completed.
5) And (5) a front sand removal process. And (3) putting the steamed slurry into a desanding machine for desanding, wherein the pressure is controlled to be 0.30Mpa, the concentration of the slurry is controlled to be 0.4%, and the desanding rate is 30min/t.
6) And (5) a pre-pulping process. Transferring the degritted slurry into a first large taper refiner for pre-pulping, wherein the pulping current is controlled at 180A, and the slurry concentration is controlled at 1.0%; the beating rate was 30min/t.
7) And (3) a concentration step. And (3) transferring the pulp after the front pulping into a side pressure cylinder thickener for concentration, wherein the pulp concentration is controlled at 10%.
8) And (3) a hydrogen peroxide bleaching process.
a: transferring the concentrated slurry into a medium concentration mixer, adding diethylenetriamine pentaacetic acid and hydrogen peroxide, introducing steam, mixing at 90 ℃ for 30min, and transferring into a hydrogen peroxide bleaching tower; wherein, the dosage of the diethylenetriamine pentaacetic acid is 0.17% of the mass of the absolute dry pulp, and the dosage of the hydrogen peroxide is 2.2% of the mass of the absolute dry pulp;
b: bleaching in hydrogen peroxide bleaching tower at 90 deg.c for 100min, diluting with deionized water to reach pulp concentration of 1%, washing with deionized water to neutrality, and acid treating in acid treating tower.
9) And (3) an acid treatment procedure. Adding hydrochloric acid (concentration 350 g/L) with the relative absolute dry pulp amount of 2% for acid treatment, wherein the acid treatment time is 30min, washing with deionized water for 2 hours, and transferring into a post-desander.
10 Post-desanding procedure: and (3) transferring the slurry subjected to acid treatment into a post-desanding machine, wherein the pressure of post-desanding is controlled at 0.3Mpa, the concentration of the slurry is controlled at 0.5%, the desanding rate is 30min/t, and transferring the slurry into a second large-taper refiner after desanding.
11 Post-pulping process: the current control of the second large taper refining machine is 160A, the pulp concentration is controlled to be 2.5%, the pulping speed is 30min/t, and the pulp is transferred into a pulp making machine after refining.
12 Pulp making process: the pulp concentration on the long wire of the pulp machine is controlled at 8g/L, the pressure of a drying cylinder is 0.20Mpa, and the finished product of cotton pulp for the lithium battery-grade cellulose ether is prepared after pulp making is completed.
The lithium battery grade cellulose ether prepared in example 4 was tested with a cotton pulp finished product, and specific indexes of the product are shown in table 4:
table 4 example 4 detection index of cotton pulp for lithium cell grade cellulose ether
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Example 5
A production process of high-purity and low-dust cotton pulp for lithium battery-grade cellulose ether comprises the following steps:
1) Selecting materials, opening cotton, and removing impurities by a dry method. Three types of first-grade cotton linters with the maturity of more than or equal to 80 percent are selected, and are loosened and decontaminated respectively through a multi-roller loosening machine and a heavy slag remover after being torn by a cotton opener, and then are transferred into a cotton extruder and are sent to an enzyme-assisted wet purification process through a cyclone separator
2) Enzyme assisted wet clean up procedure. Mixing the carefully selected cotton linters with the black liquor, enabling the concentration of the carefully selected cotton linters in a system to be 5%, enabling the pH value of the system to be 4-6, adding a mixed enzyme preparation for enzymolysis for 60min, and conveying the mixture to the next working procedure through a screw after the enzymolysis is finished; (the amount of the surfactant fatty alcohol-polyoxyethylene ether phosphate in the mixed enzyme preparation was 0.5 kg/ton, the amount of the pectase was 0.5 kg/ton, the amount of the xylanase was 0.5 kg/ton, and the amount of the resin controlling enzyme was 0.5 kg/ton)
3) And (3) a continuous electrocatalytic process. And adding hydrogen peroxide into the selected cotton linters after enzymolysis and performing electrocatalysis, wherein the electrocatalysis time is 30min, the temperature is 60 ℃, and the consumption of the hydrogen peroxide is 2.0% of the mass of the absolute dry pulp.
4) Alkali preparation, soaking and stewing. The alkali compounding temperature is controlled at 80 ℃, the total alkali is 6 percent relative to the weight of absolute dry pulp calculated by NaOH, and Na 2 SO 3 Is of the phase0.4% of the weight of the absolute dry pulp; naOH was formulated as 40g/L lye and Na was added 2 SO 3 Adding the mixed solution into alkali liquor to obtain prepared alkali liquor; then the prepared alkali liquor is injected into a rotary spherical digester and fully mixed with the cotton linters which are loaded into the rotary spherical digester and subjected to electric catalysis through cold transfer for impregnation; then heating and steaming the materials in the steaming ball, wherein the steaming temperature is 120 ℃, the steaming time is 120min, and the next procedure is carried out after the steaming is completed.
5) And (5) a front sand removal process. And (3) putting the steamed slurry into a desanding machine for desanding, wherein the pressure is controlled to be 0.30Mpa, the concentration of the slurry is controlled to be 0.4%, and the desanding rate is 30min/t.
6) And (5) a pre-pulping process. Transferring the degritted slurry into a first large taper refiner for pre-pulping, wherein the pulping current is controlled at 180A, and the slurry concentration is controlled at 1.0%; the beating rate was 30min/t.
7) And (3) a concentration step. And (3) transferring the pulp after the front pulping into a side pressure cylinder thickener for concentration, wherein the pulp concentration is controlled at 10%.
8) And (3) a hydrogen peroxide bleaching process.
a: transferring the concentrated slurry into a medium concentration mixer, adding diethylenetriamine pentaacetic acid and hydrogen peroxide, introducing steam, mixing at 90 ℃ for 30min, and transferring into a hydrogen peroxide bleaching tower; wherein, the dosage of the diethylenetriamine pentaacetic acid is 0.17% of the mass of the absolute dry pulp, and the dosage of the hydrogen peroxide is 2.2% of the mass of the absolute dry pulp;
b: bleaching in hydrogen peroxide bleaching tower at 90 deg.c for 100min, diluting with deionized water to reach pulp concentration of 1%, washing with deionized water to neutrality, and acid treating in acid treating tower.
9) And (3) an acid treatment procedure. Adding hydrochloric acid (concentration 350 g/L) with the relative absolute dry pulp amount of 2% for acid treatment, wherein the acid treatment time is 30min, washing with deionized water for 2 hours, and transferring into a post-desander.
10 Post-desanding procedure: and (3) transferring the slurry subjected to acid treatment into a post-desanding machine, wherein the pressure of post-desanding is controlled at 0.3Mpa, the concentration of the slurry is controlled at 0.5%, the desanding rate is 30min/t, and transferring the slurry into a second large-taper refiner after desanding.
11 Post-pulping process: the current control of the second large taper refining machine is 160A, the pulp concentration is controlled to be 2.5%, the pulping speed is 30min/t, and the pulp is transferred into a pulp making machine after refining.
12 Pulp making process: the pulp concentration on the long wire of the pulp machine is controlled at 8g/L, the pressure of a drying cylinder is 0.20Mpa, and the finished product of cotton pulp for the lithium battery-grade cellulose ether is prepared after pulp making is completed.
The lithium battery grade cellulose ether prepared in example 5 was tested with a cotton pulp finished product, and specific indexes of the product are shown in table 15:
table 5 example 5 detection index of cotton pulp for lithium cell grade cellulose ether
Comparative example 1
A production process of conventional lithium battery-grade cellulose ether cotton pulp comprises the following steps:
1) Selecting materials, opening cotton, and removing impurities by a dry method. Three types of first-grade cotton linters with the maturity of more than or equal to 80 percent are selected, and are loosened and decontaminated respectively through a multi-roller loosening machine and a heavy slag remover after being torn by a cotton opener, and then are transferred into a cotton extruder and are sent to alkali preparation, dipping and stewing processes through a cyclone separator
2) Alkali preparation, soaking and stewing. The alkali compounding temperature is controlled at 80 ℃, the total alkali is 6 percent relative to the weight of absolute dry pulp calculated by NaOH, and Na 2 SO 3 0.4% of the weight of the relative absolute dry pulp; naOH was formulated as 40g/L lye and Na was added 2 SO 3 Adding the mixed solution into alkali liquor to obtain prepared alkali liquor; then the prepared alkali liquor is injected into a rotary spherical digester and fully mixed with the short velvet loaded into the rotary spherical digester for impregnation through cold transfer; then heating and steaming the materials in the steaming ballBoiling at 135 deg.c for 150min, and the next step.
3) And (5) a front sand removal process. And (3) putting the steamed slurry into a desanding machine for desanding, wherein the pressure is controlled to be 0.30Mpa, the concentration of the slurry is controlled to be 0.4%, and the desanding rate is 30min/t.
4) And (5) a pre-pulping process. Transferring the degritted slurry into a first large taper refiner for pre-pulping, wherein the pulping current is controlled at 180A, and the slurry concentration is controlled at 1.0%; the beating rate was 30min/t.
5) And (3) a concentration step. And (3) transferring the pulp after the front pulping into a side pressure cylinder thickener for concentration, wherein the pulp concentration is controlled at 10%.
6) And (3) a hydrogen peroxide bleaching process.
a: transferring the concentrated slurry into a medium concentration mixer, adding diethylenetriamine pentaacetic acid and hydrogen peroxide, introducing steam, mixing at 90 ℃ for 30min, and transferring into a hydrogen peroxide bleaching tower; wherein, the dosage of the diethylenetriamine pentaacetic acid is 0.17% of the mass of the absolute dry pulp, and the dosage of the hydrogen peroxide is 2.2% of the mass of the absolute dry pulp;
b: bleaching in hydrogen peroxide bleaching tower at 90 deg.c for 100min, diluting with deionized water to reach pulp concentration of 1%, washing with deionized water to neutrality, and acid treating in acid treating tower.
7) And (3) an acid treatment procedure. Adding hydrochloric acid (concentration 350 g/L) with the relative absolute dry pulp amount of 2% for acid treatment, wherein the acid treatment time is 30min, washing with deionized water for 2 hours, and transferring into a post-desander.
8) Post-desanding procedure: and (3) transferring the slurry subjected to acid treatment into a post-desanding machine, wherein the pressure of post-desanding is controlled at 0.3Mpa, the concentration of the slurry is controlled at 0.5%, the desanding rate is 30min/t, and transferring the slurry into a second large-taper refiner after desanding.
9) Post-pulping: the current control of the second large taper refining machine is 160A, the pulp concentration is controlled to be 2.5%, the pulping speed is 30min/t, and the pulp is transferred into a pulp making machine after refining.
10 Pulp making process: the pulp concentration on the long wire of the pulp machine is controlled at 8g/L, the pressure of a drying cylinder is 0.20Mpa, and the finished product of cotton pulp for the lithium battery-grade cellulose ether is prepared after pulp making is completed.
The lithium battery grade cellulose ether prepared in comparative example 1 was tested with a cotton pulp finished product, and specific indexes of the product are shown in table 6:
table 6 comparative example 1 cotton pulp detection index for lithium battery grade cellulose ether
Compared with the embodiment, the comparative example 1 has the advantages that under the condition of lacking an enzyme-assisted wet purification process, the prepared lithium battery grade cellulose ether uses more cotton pulp dust, the heavy metal content is high, the COD content of the digestion black liquor generated in the production process is high, the digestion black liquor is difficult to treat, and the environment pollution is easy to cause.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. The production process of cotton pulp for lithium battery-grade cellulose ether is characterized by comprising the following steps of: 1) Selecting materials, opening cotton and removing impurities by a dry method; 2) Enzyme-assisted wet purification; 3) A continuous electrocatalytic process; 4) Alkali preparation, dipping and stewing; 5) A front sand removal process; 6) A pre-pulping process; 7) A concentration step; 8) Bleaching with hydrogen peroxide; 9) An acid treatment step; 10 A post-desanding process; 11 A post-pulping process; 12 A pulp making process.
2. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein the steps of 1) selecting materials, opening cotton and dry impurity removing are as follows: three types of first-grade cotton linters with the maturity more than or equal to 80 percent are selected, and after tearing the cotton linters by a cotton opener, selected cotton linters are obtained through loosening and impurity removal;
the step 2) enzyme-assisted wet purification process comprises the following steps: mixing the carefully selected cotton linters with the black liquor, enabling the concentration of the carefully selected cotton linters in a system to be 5%, enabling the pH value of the system to be 4-6, and then adding a mixed enzyme preparation for enzymolysis;
the mixed enzyme preparation comprises surfactant fatty alcohol polyoxyethylene ether phosphate, pectinase, xylanase and resin control enzyme; the dosage of the surfactant fatty alcohol polyoxyethylene ether phosphate is 0.5-1 kg/ton, the dosage of the pectase is 0.5-1 kg/ton, the dosage of the xylanase is 0.5-1 kg/ton and the dosage of the resin control enzyme is 0.5-1 kg/ton; the enzymolysis time is 60min;
the step 3) continuous electrocatalytic process comprises the following steps: adding hydrogen peroxide into the selected cotton linters after enzymolysis and performing electrocatalysis, wherein the electrocatalysis time is 20-30 min, the temperature is 60-70 ℃, and the dosage of the hydrogen peroxide is 1.0-2.0% of the mass of absolute dry pulp.
3. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein the alkali preparation procedure in the step 4) is as follows: alkali is prepared at 80-85 ℃, the total alkali is 6-10% of the absolute dry pulp mass calculated by NaOH, and Na is used as the alkali 2 SO 3 0.4 to 0.8 percent of the mass of the absolute dry pulp; naOH was formulated as 40g/L lye and Na was added 2 SO 3 Adding the mixed solution into alkali liquor to obtain prepared alkali liquor;
the dipping procedure is as follows: the prepared alkali liquor is injected into a rotary spherical digester and fully mixed with the cotton linters after the electrocatalysis by cold transfer;
the steaming and boiling process comprises the following steps: heating and steaming the materials in the steaming ball, wherein the steaming temperature is 120-135 ℃ and the steaming time is 120min.
4. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein the step 5) of the pre-sand removal step comprises the following steps: and (3) putting the steamed slurry into a desanding machine for desanding, wherein the pressure is 0.30-0.32 Mpa, the concentration of the slurry is 0.4-0.6%, and the desanding rate is 10-30 min/t.
5. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein the pre-pulping step of step 6) is as follows: transferring the degritted slurry into a first large taper refiner for pre-pulping, wherein the pulping current is 180-200A, and the slurry concentration is 1.0% -1.8%; the pulping speed is 10-30 min/t;
the concentration procedure of the step 7) is as follows: and (3) transferring the pulp subjected to the pre-pulping into a side pressure cylinder thickener for concentration, wherein the pulp concentration is 10% -12%.
6. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein the hydrogen peroxide bleaching procedure of step 8) is as follows: transferring the concentrated slurry into a medium concentration mixer, adding diethylenetriamine pentaacetic acid and hydrogen peroxide, introducing steam, mixing at 90-110 ℃ for 20-30 min, and transferring into a hydrogen peroxide bleaching tower; wherein, the dosage of the diethylenetriamine pentaacetic acid is 0.17 to 0.22 percent of the mass of the absolute dry pulp, and the dosage of the hydrogen peroxide is 2.2 to 2.8 percent of the mass of the absolute dry pulp;
bleaching in hydrogen peroxide bleaching tower at 90-110 deg.c for 100-120 min, diluting with deionized water to reach pulp concentration of 1-1.5%, washing with deionized water to neutrality, and acid treating in acid treating tower.
7. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein the acid treatment step of step 9) comprises the following steps: adding hydrochloric acid with the relative absolute dry pulp amount of 2-2.5% for acid treatment, wherein the acid treatment time is 20-40 min, and then washing with deionized water for 2-3 hours; the concentration of the hydrochloric acid is 350g/L.
8. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein the post-sand removal step of step 10) comprises the following steps: and (3) transferring the slurry subjected to acid treatment into a post-desanding machine, wherein the pressure of post-desanding is more than or equal to 0.3Mpa, the concentration of the slurry is 0.5% -0.7%, the desanding rate is 10-30 min/t, and transferring the slurry into a second large-taper refiner after desanding.
9. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein the post-pulping step of step 11) comprises: and (3) transferring the pulp subjected to the sand removal into a second large taper refiner for post-pulping, wherein the pulping current is 160-180A, the pulp concentration is 2.5-2.7%, the pulping speed is 10-30 min/t, and transferring into a pulp making machine after refining.
10. The process for producing cotton pulp for lithium battery grade cellulose ether according to claim 1, wherein in the pulp making step of step 12), pulp concentration on a wire of a pulp making machine is 8-12 g/L, and drying cylinder pressure is less than or equal to 0.20Mpa and is not 0, and a finished product is obtained after pulp making is completed.
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