A process for the preparation of papermaking sludge colloids for the addition of papermaking sludge

Abstract

The present application relates to the field of papermaking, and discloses a process method for adding papermaking sludge by preparing papermaking sludge colloid, comprising the following steps: S1, sludge recovery, and modulating into thick sludge slurry with a sludge weight content percentage of 20-25%; S2, preparing modified starch; S3, adding the modified starch obtained in S2 into the sludge slurry obtained in S1, and continuously stirring; S4, adding cationic polyacrylamide into the mixed solution obtained in S3; S5, conveying the mixed colloid solution obtained in S4 to a fine screening pressure screen to screen impurities; S6, conveying the colloid mixed solution screened in S5 to the front of a slurry pump, and after dilution water and dilution screening and dispersion treatment by a front screen, entering a headbox, and being formed into finished paper by a paper machine. The present application has the following advantages and effects: having the activity of inhibiting microorganisms, prolonging the storage time of sludge, and simultaneously capturing fine fibers in the sludge, thereby facilitating the effect of reuse.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of papermaking, in particular to a process method for adding papermaking sludge by preparing papermaking sludge colloid. BACKGROUND

[0002] After the wastewater in the papermaking production process is treated by physical and biological methods, more than 90% of the suspended solids are separated out as sludge, and 90% of the sludge is fine fibers. After the sludge containing a large amount of fine fibers is subjected to sedimentation and pressure filtration, it is treated by dehydration and incineration, which is not economical due to the low heat value of the sludge; it is treated by dehydration and landfill, which easily pollutes the environment and easily produces odor to pollute the air; it is used to make fertilizer, which has a small amount of use, large pollution and unclear effect; it is used to make building materials through a complex process, which is not economical due to the complex process and high transportation cost; it is used to make corrugated paper through a spraying method, which has a small amount of reuse; in the papermaking production process, the odor in the papermaking workshop is heavy, the odor of the papermaking white water is large, and the production water system is easily polluted and bacteria are easily bred.

[0003] If the fine fibers are retained and recycled for papermaking, not only can the resources be reused and pollution be reduced, but also the enterprise benefit can be increased. However, the cellulose in the sludge is easily degraded by microorganisms, and the microbial degradation of the fibers determines the storage time of the sludge. The microbial degradation can be characterized and determined by the oxygen consumption. Studies have shown that the oxygen consumption of different sludge has a large difference, generally (48±49) mg / (gh). The cellulose degrades faster than other components of wood, and 1.06 g of oxygen is consumed for the complete degradation of 1 g of cellulose under the action of aerobic respiration. The average oxygen consumption shows that about 12% of the fibers in the sludge stored for 1 month are degraded (assuming that the fiber content in the sludge is 50%), and 0.5 g of microorganisms is produced for every 1 g of substrate consumed.

[0004] Therefore, how to inhibit the activity of microorganisms, prolong the storage time of the sludge, and capture the fine fibers in the sludge for convenient reuse is a technical problem that needs to be solved in the papermaking industry at present. SUMMARY

[0005] The purpose of the present application is to provide a process method for adding papermaking sludge by preparing papermaking sludge colloid, which has the effects of inhibiting the activity of microorganisms, prolonging the storage time of the sludge, and capturing the fine fibers in the sludge for convenient reuse.

[0006] The above technical purpose of the present application is realized by the following technical scheme: a process method for adding papermaking sludge by preparing papermaking sludge colloid, comprising the following steps:

[0007] S1, sludge recovery, and preparation of thick slurry with a sludge weight content of 20-25%;

[0008] S2, preparing modified starch;

[0009] S3, adding the modified starch obtained in S2 into the sludge slurry obtained in S1 and continuously stirring;

[0010] S4, steaming the mixture obtained in S3 until the temperature of the mixture reaches 95-100 DEG C and continuously stirring;

[0011] S5, cooling the mixture obtained in S4 to 20-45 DEG C through a heat exchange device;

[0012] S6, adding cationic polyacrylamide into the mixture obtained in S5;

[0013] S7, conveying the mixture obtained in S6 to a fine screening pressure screen to screen impurities;

[0014] S8, conveying the colloidal mixture screened in S7 to a dilution screen before a dilution water and a front screen for dilution screening and dispersion treatment, and then entering a headbox to be formed into finished paper by a paper machine.

[0015] The application further provides a preparation method of the modified starch.

[0016] A (4-carboxybutyl)triphenylphosphonium bromide TPB and dimethyl sulfoxide DMSO solution is added in a reaction container in a proportion, an activating agent N-hydroxysuccinimide NHS and 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC are added and dissolved by stirring, and an aqueous hydrochloric acid solution is used to adjust the PH value of the solution to 5, and stirring is carried out at 25 DEG C for 12 h;

[0017] After the activation is completed, a certain amount of a starch and 4-dimethylaminopyridine DMAP mixed aqueous solution (50 wt.%) is added dropwise, and an aqueous hydrochloric acid solution is used to adjust the PH to 2, and stirring is carried out at 25 DEG C, after the reaction is completed, the mixture is poured into excess acetone to obtain a precipitate, and the precipitate obtained by filtration is dried in a vacuum environment at 40 DEG C to obtain the modified starch.

[0018] The application further provides that the molar ratio of the (4-carboxybutyl)triphenylphosphonium bromide TPB, 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC and N-hydroxysuccinimide NHS is 1:1.5:1.

[0019] The application further provides that the feeding ratio of the starch and the (4-carboxybutyl)triphenylphosphonium bromide TPB is 1:(1-3).

[0020] The application further provides that in S3, the adding ratio of the modified starch to the sludge slurry is 1:5.

[0021] The further arrangement of the present application is that in the S6, the weight percentage of the cationic polyacrylamide is 0.1%-0.5%.

[0022] The further arrangement of the present application is that in the S6, the concentration of the colloidal mixed solution is 3%-3.5%.

[0023] The further arrangement of the present application is that in the S7, the screen gap of the pressure screen is 0.18-0.25mm.

[0024] The beneficial effects of the present application are:

[0025] 1. By the modification of the quaternary phosphonium salt, the number of quaternary phosphine functional groups and the molecular weight and charge of the modified starch are greatly improved, thereby improving the bridging and electric neutralization flocculation performance of the modified starch. In addition to the good flocculation performance, the modified starch also has bacteriostatic and sterilization effects. This dual functionality is mainly due to the introduction of the cationic quaternary phosphine group on the starch chain, so that the modified starch can not only flocculate and settle cellulose, but also effectively destroy the bacterial cell wall and kill bacteria, reduce the production of by-products, and prolong the storage time of sludge.

[0026] 2. The enhanced bactericidal effect of the modified starch in papermaking sludge can directly kill bacteria, and the antibacterial effect is not a simple flocculation. First, the modified starch electrically neutralizes and destroys the negatively charged microorganisms. In this process, part of the cells are adsorbed due to charge attraction, and at the same time, a large number of unstable cells are adsorbed on the surface of the modified starch, and are aggregated to form micro-flocs by van der Waals force and electrostatic attraction. Finally, the flocs settle to the bottom together with the inactivated bacterial cells.

[0027] 3. The gelatinized starch sludge is fully mixed with the cationic polyacrylamide solution to fully adsorb and combine the excess negative charge in the sludge with the cationic polyacrylamide to form larger sludge particles, which are easy to bed on the forming wire and not lost by filtration.

[0028] 4. In step S4, the temperature of the mixed solution is lower than 95℃, and the starch gelatinization effect is not good. If the temperature is higher than 100℃, energy will be wasted. The temperature reduction in S5 is to prepare for the subsequent addition of cationic polyacrylamide, to slow down the hydrolysis rate of cationic polyacrylamide.

[0029] 5. The screened colloidal mixed solution is transported to the dilution water and the dilution screen before the screen, and then enters the headbox, and is formed into finished paper by the paper machine. The excess positive charge in the colloid will be firmly adsorbed with the negative charge of the pulp together to form a uniform pulp mixture, which is transported to the forming wire for dewatering, and at the same time, the loss rate of small fibers in the pulp system can be reduced.

[0030] 6. The reuse of the papermaking sludge colloid reduces the environmental pollution of papermaking solid waste, reduces the harmful gas emissions generated by the papermaking sludge, and kills the microorganisms in the papermaking sludge, reducing the odor of the papermaking sludge in the papermaking process;

[0031] 7. The reuse of the papermaking sludge can directly reduce the amount of fiber raw materials, and can save 5-15% of papermaking fiber raw materials, with significant saving effect;

[0032] 8. The papermaking sludge colloid can be applied to a wide range of paper types and can be added to industrial packaging paper with a grammage of 50 grams or more, without affecting the forming machine. The papermaking sludge colloid can be stably added to the gap, the stack, the long net, and the round net paper machine. The reuse of the papermaking sludge colloid reduces the environmental pollution of papermaking solid waste and reduces the harmful gas emissions generated by the papermaking sludge. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments will be described below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] Embodiment 1:

[0035] A process for adding papermaking sludge by preparing papermaking sludge colloid, comprising the following steps:

[0036] S1, sludge recovery, and preparation of thick sludge slurry with a sludge weight content of 20-25%;

[0037] S2, preparation of modified starch, comprising the following steps: adding (4-carboxybutyl)triphenylphosphonium bromide TPB and dimethyl sulfoxide DMSO solution in proportion in a reaction vessel, adding activator N-hydroxysuccinimide NHS and 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, and stirring and dissolving, the molar ratio of the three (4-carboxybutyl)triphenylphosphonium bromide TPB, 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, N-hydroxysuccinimide NHS is 1:1.5:1, the PH value of the solution is adjusted to 5 with hydrochloric acid solution, and stirring at 25℃ for 12h;

[0038] After the activation is completed, a certain amount of a mixed aqueous solution of starch and 4-dimethylaminopyridine DMAP (50 wt.%) is added dropwise, the starch and (4-carboxybutyl)triphenylphosphonium bromide TPB are added in a ratio of 1:1, and the pH is adjusted to 2 with an aqueous hydrochloric acid solution, and the reaction is stirred at 25°C. After the reaction is completed, the mixture is poured into excess acetone to obtain a precipitate, and the precipitate obtained by filtration is dried in a vacuum environment at 40°C to obtain modified starch.

[0039] S3, in the sludge slurry obtained in S1, the modified starch obtained in S2 is added, and the addition ratio of the modified starch to the sludge slurry is 1:5, and the stirring is continued;

[0040] S4, steam is introduced into the mixture obtained in S3 until the temperature of the mixture reaches 95-100°C, and the stirring is continued at a speed of 20-30 revolutions per minute;

[0041] S5, the mixture obtained in S4 is cooled to 20-45°C by a heat exchange device;

[0042] S6, cationic polyacrylamide is added to the mixture obtained in S5, the weight percentage of the cationic polyacrylamide is 0.1%-0.5%, and the concentration of the colloidal mixture is 3%-3.5%;

[0043] S7, the colloidal mixture obtained in S6 is transported to a fine screening pressure screen to screen impurities, and the gap between the screen slots of the pressure screen is 0.18-0.25mm;

[0044] S8, the colloidal mixture screened in S7 is transported to a dilution screen before a dilution screen and a front screen, and is dispersed and treated by dilution, and then is fed into a headbox, and is formed into finished paper by a paper machine.

[0045] Example 2:

[0046] The difference between Example 2 and Example 1 is that:

[0047] S2, preparing modified starch, including the following steps: adding (4-carboxybutyl)triphenylphosphonium bromide TPB and dimethyl sulfoxide DMSO solution in a reaction container in a certain proportion, adding activator N-hydroxysuccinimide NHS and 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, and stirring and dissolving, the molar ratio of the three of (4-carboxybutyl)triphenylphosphonium bromide TPB, 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, and N-hydroxysuccinimide NHS is 1:1.5:1, the pH value of the solution is adjusted to 5 with an aqueous hydrochloric acid solution, and the stirring is continued at 25°C for 12h;

[0048] After the activation is completed, a certain amount of starch and 4-dimethylaminopyridine DMAP mixed aqueous solution (50wt.%) is added dropwise, the starch and (4-carboxybutyl)triphenylphosphonium bromide TPB are in a feeding ratio of 1:1.5, and the PH is adjusted to 2 with an aqueous hydrochloric acid solution, the reaction is stirred at 25°C, after the reaction is completed, the mixture is poured into excess acetone to obtain a precipitate, and the precipitate obtained by filtration is dried in a vacuum environment at 40°C to obtain modified starch.

[0049] Example 3:

[0050] The difference between Example 3 and Example 1 is that:

[0051] S2, preparation of modified starch, including the following steps: adding (4-carboxybutyl)triphenylphosphonium bromide TPB and dimethyl sulfoxide DMSO solution in a reaction container, adding activators N-hydroxysuccinimide NHS and 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, and stirring and dissolving, the molar ratio of the three of (4-carboxybutyl)triphenylphosphonium bromide TPB, 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, and N-hydroxysuccinimide NHS is 1:1.5:1, the PH value of the solution is adjusted to 5 with an aqueous hydrochloric acid solution, and stirring is carried out at 25°C for 12h;

[0052] After the activation is completed, a certain amount of starch and 4-dimethylaminopyridine DMAP mixed aqueous solution (50wt.%) is added dropwise, the starch and (4-carboxybutyl)triphenylphosphonium bromide TPB are in a feeding ratio of 1:1.5, and the PH is adjusted to 2 with an aqueous hydrochloric acid solution, the reaction is stirred at 25°C, after the reaction is completed, the mixture is poured into excess acetone to obtain a precipitate, and the precipitate obtained by filtration is dried in a vacuum environment at 40°C to obtain modified starch.

[0053] Example 4:

[0054] The difference between Example 4 and Example 1 is that:

[0055] S2, preparation of modified starch, including the following steps: adding (4-carboxybutyl)triphenylphosphonium bromide TPB and dimethyl sulfoxide DMSO solution in a reaction container, adding activators N-hydroxysuccinimide NHS and 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, and stirring and dissolving, the molar ratio of the three of (4-carboxybutyl)triphenylphosphonium bromide TPB, 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, and N-hydroxysuccinimide NHS is 1:1.5:1, the PH value of the solution is adjusted to 5 with an aqueous hydrochloric acid solution, and stirring is carried out at 25°C for 12h;

[0056] After the activation is completed, a certain amount of starch and 4-dimethylaminopyridine DMAP mixed aqueous solution (50wt.%) is added dropwise, the feeding ratio of the starch and (4-carboxybutyl) triphenylphosphonium bromide TPB is 1:0.5, and the PH is adjusted to 2 with an aqueous hydrochloric acid solution, and the reaction is stirred at 25℃. After the reaction is completed, the mixture is poured into excess acetone to obtain a precipitate, and the precipitate obtained by filtration is dried in a vacuum environment at 40℃ to obtain modified starch.

[0057] Example 5:

[0058] The difference between Example 5 and Example 1 is that:

[0059] S2, the thick sludge slurry prepared in S1 is fermented by composite microorganisms, and the fermentation is carried out at 20-40℃ for 2-5 days.

[0060] S3, cationic polyacrylamide is added to the mixed solution after fermentation, and the weight percentage of cationic polyacrylamide is 0.1%-0.5%, so that the concentration of the colloidal mixed solution is 3%-3.5%;

[0061] S4, the colloidal mixed solution obtained in S3 is transported to a fine selection pressure screen to screen impurities, and the gap between the screen slots of the pressure screen is 0.18-0.25mm.

[0062] S5, the colloidal mixed solution screened in S4 is transported to the front of the slurry pump, and after dilution and screening dispersion treatment by dilution water and a front screen, it enters the headbox and is formed into finished paper by the paper machine.

[0063] Example 6:

[0064] The difference between Example 5 and Example 1 is that:

[0065] S2, the modified starch is prepared, and the modified starch is carboxymethyl cationic modified starch.

[0066] Example 7:

[0067] The difference between Example 5 and Example 1 is that:

[0068] S2, the modified starch is prepared, and the modified starch is quaternary ammonium salt cationic modified starch.

[0069] Test process:

[0070] (1) Microbial content determination: The sludge colloids are prepared by the schemes of Examples 1-7, and the sludge before treatment, the sludge after treatment, and the sludge colloids are tested respectively. According to the national standard GB / T38488-2021 "Microorganism rapid determination method", the number change of microorganisms in the sludge before and after flocculation is determined.

[0071] (2) Cellulose content determination: The sludge colloid was prepared according to the scheme of Examples 1-7, and the performance of the sludge colloid was tested, and the cellulose content in the sludge colloid was tested according to the standard GB / T267710-1995.

[0072] (3) Industrial packaging paper preparation: The sludge colloid was prepared according to the scheme of Examples 1-7, and the sludge colloid was mixed with papermaking raw materials, and then the sludge colloid was stirred, the water quality was adjusted, and the filter paper was processed, and then the starch was coated on the paper web, and then the industrial packaging paper was obtained after drying and finishing.

[0073] Test results

[0074] According to the experimental process (1), the microbial content in Examples 1-7 was measured, and the experimental results are shown in Table 1:

[0075]

[0076] Table 1 Change in the number of microorganisms in sludge before and after flocculation

[0077] According to the experimental process (2), the cellulose content in the sludge colloid prepared in Examples 1-7 was measured, and the experimental results are shown in Table 2:

[0078] Oxygen consumption / mg g -1 h -1 ]]> Ash content / % Fiber content / % Number average fiber length / mm Drainage (60 s), g Example 1 13 92 90 3.3 655 Example 2 7 93.2 93 3.9 648 Example 3 11 92.7 95 2.5 650 Example 4 15 90 88 1.8 636 Example 5 18 75 86 1 526 Example 6 44 86 82 1.6 546 Example 7 36 87.1 85 2 588

[0079] Table 2 Test results of cellulose content

[0080] According to the experimental process (3), the sludge colloid prepared in Examples 1-7 was added to the papermaking raw materials, and the industrial packaging paper was prepared, and the experimental results are shown in Table 2:

[0081]

[0082]

[0083] Table 3 Test results of the performance of the finished paper

[0084] As can be seen from Table 3, the sludge colloid prepared by using modified starch has no obvious effect on the physical performance indicators of the paper, and the addition of the sludge colloid increases the reuse of resources.

Claims

1. A process for the preparation of papermaking sludge colloids for the addition of papermaking sludge, characterized by: It comprises the following steps: S1, sludge recovery, and preparation of thick slurry with sludge weight content of 20-25%; S2, preparation of modified starch; S3, addition of modified starch obtained in S2 to the slurry obtained in S1, and continuous stirring; S4, steam cooking of the mixture obtained in S3 until the temperature of the mixture reaches 95-100℃, and continuous stirring; S5, cooling of the mixture obtained in S4 to 20-45℃ by heat exchange device; S6, addition of cationic polyacrylamide to the mixture obtained in S5; S7, delivery of the mixture obtained in S6 to a fine screening pressure screen to screen out impurities; S8, delivery of the screened mixture to a dilution screen before a dilution water and a front screen for dilution and dispersion, and then into a headbox, and then into a paper machine to form a finished paper; The preparation method of the modified starch is as follows: In a reaction vessel, (4-carboxybutyl)triphenylphosphonium bromide TPB and dimethyl sulfoxide DMSO solution are added in proportion, activators N-hydroxysuccinimide NHS and 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC are added, and the solution is stirred and dissolved, the pH value of the solution is adjusted to 5 with hydrochloric acid aqueous solution, and stirred at 25℃ for 12h; After the activation is completed, a certain amount of starch and 4-dimethylaminopyridine DMAP mixed aqueous solution is added dropwise, and the pH is adjusted to 2 with hydrochloric acid aqueous solution, and the reaction is stirred at 25℃, after the reaction is completed, the mixture is poured into excess acetone to obtain a precipitate, and the precipitate obtained by filtration is dried in a vacuum environment at 40℃ to obtain modified starch; The molar ratio of (4-carboxybutyl)triphenylphosphonium bromide TPB, 1-ethyl-(3-dimethylaminopropyl) carbonyldiimidazole EDC, and N-hydroxysuccinimide NHS is 1:1.5:1; The feeding ratio of starch and (4-carboxybutyl)triphenylphosphonium bromide TPB is 1:(1-3).

2. A process for the preparation of paper mill sludge colloids for the addition of paper mill sludge according to claim 1, characterized by: In S3, the addition ratio of modified starch to slurry is 1:

5.

3. A process for the preparation of paper mill sludge colloids for the addition of paper mill sludge according to claim 1, characterized by: In S6, the weight percentage of cationic polyacrylamide is 0.1%-0.5%.

4. A process for the preparation of paper mill sludge colloids for the addition of paper mill sludge according to claim 1, characterized by: In S6, the concentration of the colloidal mixture is 3%-3.5%.

5. A process for the preparation of paper mill sludge colloids for the addition of paper mill sludge according to claim 1, characterized by: In S7, the gap between the screen slots of the pressure screen is 0.18-0.25mm.

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