阅读说明：本技术 一种废纸脱墨及镁碱基过氧化氢漂白方法 (Method for deinking waste paper and bleaching magnesium-base hydrogen peroxide ) 是由 云娜 张舒心 卞喻 蔡永辉 于 2020-03-11 设计创作，主要内容包括：本发明属于废纸制浆造纸技术领域,公开了一种废纸脱墨及镁碱基过氧化氢漂白方法。该方法经废纸浆原料的准备、表面活性剂预处理、打浆、超声波浮选、洗涤脱墨、过氧化氢漂白及纸张抄造等步骤,通过对脱墨工艺的创新改进,在打浆操作前进行表面活性剂的预处理,通过表面活性剂丙烯酸和异佛尔酮二异氰酸酯之间的协同作用,可有效增强后续废纸脱墨的效果,增强纸张强度。并对过氧化氢漂白工艺进行改进,以漆酶作为预漂白剂,硫酸镁、硅酸钠以及氢氧化钠作为漂白保护剂,过氧化氢作为漂白剂,异壬酰氧苯磺酸钠作为助漂剂,漂白后的废纸脱墨浆强度好,白度高、白度稳定性好,而且显著降低漂白废液中的COD值。(The invention belongs to the technical field of pulping and papermaking of waste paper, and discloses a method for deinking of waste paper and bleaching of magnesium-based hydrogen peroxide. The method comprises the steps of waste paper pulp raw material preparation, surfactant pretreatment, pulping, ultrasonic flotation, washing deinking, hydrogen peroxide bleaching, paper making and the like, and the pretreatment of the surfactant is carried out before pulping operation through the innovative improvement of a deinking process, so that the subsequent waste paper deinking effect can be effectively enhanced and the paper strength can be enhanced through the synergistic effect between the surfactant acrylic acid and isophorone diisocyanate. The bleaching process of hydrogen peroxide is improved, laccase is used as a pre-bleaching agent, magnesium sulfate, sodium silicate and sodium hydroxide are used as bleaching protective agents, hydrogen peroxide is used as a bleaching agent, sodium isononanoyloxybenzene sulfonate is used as a bleaching assistant, bleached waste paper deinking pulp is good in strength, high in whiteness and good in whiteness stability, and the COD value in bleaching waste liquid is remarkably reduced.)

1. A waste paper deinking and magnesium-based hydrogen peroxide bleaching method is characterized by comprising the following specific steps:

s1, preparation of a waste paper pulp raw material: cutting waste paper into paper sheets, soaking the paper sheets in distilled water, and dehydrating the paper sheets until the water content is 30-40% to obtain a waste paper raw material;

s2, pretreating a surfactant, namely adding a waste paper raw material into 35-45 ℃ water to dilute the waste paper raw material to a concentration of 40-60 g/L, adding a surfactant acrylic monomer and isophorone diisocyanate, and stirring, wherein the mass ratio of the waste paper raw material to the acrylic monomer to the isophorone diisocyanate is 100 (0.1-0.16) to (0.06-0.1), so as to prepare a pretreated waste paper pulp of the surfactant;

s3, pulping, namely adding the waste paper pulp pretreated by the surfactant into a pulping machine, adding water with the temperature of 35-45 ℃ to dilute the waste paper pulp to the concentration of 15-25 g/L, adding deinking agents of fatty alcohol-polyoxyethylene ether sodium sulfate and lauric acid diethanol amine, wherein the mass ratio of the waste paper pulp pretreated by the surfactant to the fatty alcohol-polyoxyethylene ether sodium sulfate to the lauric acid diethanol amine is 20 (0.03-0.05) to (0.05-0.08), adding sodium hydroxide to adjust the pH value of the pulp to 8-9, and deinking to prepare pulp;

s4, ultrasonic flotation, washing and deinking, namely adding the pulp into water with the temperature of 40 ℃ to dilute the pulp to 5-10 g/L, then adding the pulp into an XFD flotation tank for flotation, wherein an ultrasonic generator is installed in the XFD flotation tank, the XFD flotation tank is always started in the flotation process, the pulp subjected to flotation and deinking is washed by a cloth bag with 80-100 meshes, then screened by a pulp screen, dewatered and dried to obtain waste paper deinking pulp;

s5, hydrogen peroxide bleaching: preparing waste paper deinking pulp into a waste paper deinking pulp solution to be bleached with the mass percentage concentration of 5-10%, and adding the waste paper deinking pulp solution into the waste paper deinking pulp solution according to the mass ratio of (1-3): (0.3-1): (0.7-2): (2.5-3.5): (0.4-0.6): (0.01-0.05) uniformly stirring sodium silicate, magnesium sulfate, sodium hydroxide, hydrogen peroxide, isononyl oxybenzene sodium sulfonate and laccase bleaching agent, carrying out bleaching reaction at 55-100 ℃, cooling and cleaning to obtain bleached waste paper deinking pulp;

s6, paper making: selecting bleached waste paper deinking pulp, and using a sheet making machine to make the basis weight of 58-62 g/m²The paper of (1).

2. The process for deinking waste paper and bleaching with magnesium-based hydrogen peroxide according to claim 1, wherein the size of said paper sheet in step S1 is (20-30) × (20-30) mm.

3. The process for deinking waste paper and bleaching with magnesium-based hydrogen peroxide according to claim 1, wherein the ratio of the mass of the waste paper to the volume of the distilled water in step S1 is 200g (1-5) L.

4. The process for deinking waste paper and bleaching with magnesium-based hydroperoxide according to claim 1, wherein the soaking time in the step S1 is 24-36 h.

5. The process for deinking waste paper and bleaching with magnesium-based hydroperoxide according to claim 1, wherein the stirring time in step S2 is 5-6 hours.

6. The process for deinking waste paper and bleaching with magnesium-based hydroperoxide according to claim 1, wherein the time for deinking by beating in step S3 is 20-30 min.

7. The process for deinking waste paper and bleaching with magnesium-based hydrogen peroxide according to claim 1, wherein the time for the flotation in step S4 is 10-20 min.

8. The process for deinking waste paper and bleaching with magnesium-based hydroperoxide according to claim 1, wherein said bleaching agent is added in the order of: adding laccase, continuously stirring at 55-65 ℃, and keeping the temperature for 25-35 min; then heating to 75-85 ℃, sequentially adding hydrogen peroxide, magnesium sulfate, sodium hydroxide and sodium silicate, and reacting for 30-90 min; and finally, heating to 90-100 ℃, adding sodium isononanoyloxybenzene sulfonate, and reacting for 20-30 min.

9. The process of deinking waste paper and bleaching with magnesium-based hydroperoxide according to claim 1, wherein the bleaching agent in step S5 accounts for 1 to 3% of the total mass of the deinked waste paper pulp.

10. The process for deinking waste paper and bleaching with magnesium-based hydroperoxide according to claim 1, wherein the bleaching reaction time in step S5 is 90-150 min.

Technical Field

The invention belongs to the technical field of pulping and papermaking of waste paper, and particularly relates to a method for deinking of waste paper and bleaching of magnesium-based hydrogen peroxide.

Background

The problems of shortage of plant fiber raw materials for papermaking and environmental pollution are always main obstacles for restricting the continuous and healthy development of the pulping and papermaking industry in China. In recent years, the waste paper pulping and papermaking process is gradually concerned and developed rapidly with the advantages of lower raw material cost, environmental pollution load and the like. The recycling of the waste paper is an effective way for solving the problems of resource shortage, energy waste and serious pollution faced by the paper industry. The recycled pulp after the waste paper is crushed reduces the whiteness of paper in the processes of crushing and deinking, so the bleaching technology of the paper pulp plays an important role in the production process of pulping and papermaking of the waste paper, and has close relation with the quality, material and energy consumption of the paper pulp and the finished paper and the influence on the environment.

In the process of pulping and papermaking by waste paper, a deinking process and a bleaching process have great influence on the final quality of paper pulp, and the currently commonly used process for deinking and bleaching the waste paper comprises the following steps: deinking in a high-concentration hydrapulper, screening and purifying, washing by a washing machine, concentrating by a thickener, bleaching by a bleaching tank, pulping by a pulping machine, and papermaking by a paper machine. The existing waste paper deinking bleaching treatment process mainly has the following defects: (1) due to the advent of new technologies such as non-pressure printing and electrostatic printing, the types of inks are increasing, for example, ultraviolet light solid ink, laser printing ink, flexographic printing ink, etc., which are the main reasons for deinking difficulty, resulting in poor deinking effect of waste paper, especially the phenomenon of alkali loss to black in the process of waste paper with high lignin content, and reducing the whiteness of deinked pulp. (2) The existing hydrogen peroxide bleaching process uses sodium hydroxide as an alkaline medium. Because the strong alkalinity of the sodium hydroxide can dissolve out hemicellulose and lignin, the yield of paper pulp is reduced, and the pollution loads of BOD5 and CODcr of the wastewater are increased; meanwhile, the initial alkalinity of a paper pulp system is higher due to the sodium hydroxide, and the formed Dissolved and Colloidal Substances (DCS) bring adverse effects on the operation of a paper machine and the quality of finished paper; furthermore, large amounts of oxalic acid are formed in the hydrogen peroxide bleaching line. (3) The waste paper deinking pulp has low bleaching yield, poor strength and poor whiteness stability.

Disclosure of Invention

In order to solve the defects and shortcomings in the prior art, the invention aims to provide a waste paper deinking and magnesium-based hydrogen peroxide bleaching method, which can effectively enhance the waste paper deinking effect, obtain high-strength and high-whiteness waste paper deinked pulp and improve the whiteness stability by innovating and improving the deinking and bleaching process.

The purpose of the invention is realized by the following technical scheme:

a method for deinking waste paper and bleaching magnesium-based hydrogen peroxide comprises the following specific steps:

s1, preparation of a waste paper pulp raw material: cutting waste paper into paper sheets, soaking the paper sheets in distilled water, and dehydrating the paper sheets until the water content is 30-40% to obtain a waste paper raw material;

s2, pretreating a surfactant, namely adding a waste paper raw material into 35-45 ℃ water to dilute the waste paper raw material to a concentration of 40-60 g/L, adding a surfactant acrylic monomer and isophorone diisocyanate, and stirring, wherein the mass ratio of the waste paper raw material to the acrylic monomer to the isophorone diisocyanate is 100 (0.1-0.16) to (0.06-0.1), so as to prepare a pretreated waste paper pulp of the surfactant;

s3, pulping, namely adding the waste paper pulp pretreated by the surfactant into a pulping machine, adding water with the temperature of 35-45 ℃ to dilute the waste paper pulp to the concentration of 15-25 g/L, adding deinking agents of fatty alcohol-polyoxyethylene ether sodium sulfate and lauric acid diethanol amine, wherein the mass ratio of the waste paper pulp pretreated by the surfactant to the fatty alcohol-polyoxyethylene ether sodium sulfate to the lauric acid diethanol amine is 20 (0.03-0.05) to (0.05-0.08), adding sodium hydroxide to adjust the pH value of the pulp to 8-9, and deinking to prepare pulp;

s4, ultrasonic flotation, washing and deinking, namely adding the pulp into water with the temperature of 40 ℃ to dilute the pulp to 5-10 g/L, then adding the pulp into an XFD flotation tank for flotation, wherein an ultrasonic generator is installed in the XFD flotation tank, the XFD flotation tank is always started in the flotation process, the pulp subjected to flotation and deinking is washed by a cloth bag with 80-100 meshes, then screened by a pulp screen, dewatered and dried to obtain waste paper deinking pulp;

s5, hydrogen peroxide bleaching: preparing waste paper deinking pulp into a waste paper deinking pulp solution to be bleached with the mass percentage concentration of 5-10%, and adding the waste paper deinking pulp solution into the waste paper deinking pulp solution according to the mass ratio of (1-3): (0.3-1): (0.7-2): (2.5-3.5): (0.4-0.6): (0.01-0.05) uniformly stirring sodium silicate, magnesium sulfate, sodium hydroxide, hydrogen peroxide, isononyl oxybenzene sodium sulfonate and laccase bleaching agent, carrying out bleaching reaction at 55-100 ℃, cooling and cleaning to obtain bleached waste paper deinking pulp;

s6, paper making: selecting bleached waste paper deinking pulp, and using a sheet making machine to make the basis weight of 58-62 g/m²The paper of (1).

Preferably, the paper size in step S1 is (20-30) × (20-30) mm.

Preferably, the volume ratio of the mass of the waste paper to the distilled water in the step S1 is 200g (1-5) L.

Preferably, the soaking time in the step S1 is 24-36 h.

Preferably, the stirring time in the step S2 is 5-6 h.

Preferably, the pulping and deinking time in the step S3 is 20-30 min.

Preferably, the flotation time in the step S4 is 10-20 min.

Preferably, the sodium silicate, magnesium sulfate, sodium hydroxide, hydrogen peroxide, sodium isononanoyloxybenzene sulfonate and laccase are added in the order of step S5: adding laccase, continuously stirring at 55-65 ℃, and keeping the temperature for 25-35 min; then heating to 75-85 ℃, sequentially adding hydrogen peroxide, magnesium sulfate, sodium hydroxide and sodium silicate, and reacting for 30-90 min; and finally, heating to 90-100 ℃, adding sodium isononanoyloxybenzene sulfonate, and reacting for 20-30 min.

Preferably, the bleaching agent in the step S5 is 1-3% of the total mass of the waste paper deinking pulp.

Preferably, the bleaching reaction time in the step S5 is 90-150 min.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the waste paper deinking process is improved, the surfactant is pretreated before pulping operation, and the synergistic effect between the proper amount of the surfactant acrylic acid and the isophorone diisocyanate is added, so that the subsequent waste paper deinking effect can be effectively enhanced, and the paper strength is enhanced;

2. according to the deinking method, the fatty alcohol-polyoxyethylene ether sodium sulfate and the lauric acid diethanol amine are used as deinking agents, and deinking is carried out under the alkalescent condition that the pH value is 8-9, so that the residual concentration of the printing ink in the waste paper pulp can be effectively reduced, and the deinking effect is improved;

3. the ultrasonic wave is added for assisting in the flotation process, so that the flotation efficiency can be effectively enhanced, and the flotation effect is improved;

4. according to the invention, the hydrogen peroxide bleaching process is improved, laccase is used as a pre-bleaching agent, magnesium sulfate, sodium silicate and sodium hydroxide are used as bleaching protective agents, hydrogen peroxide is used as a bleaching agent, and sodium isononanoyloxybenzene sulfonate is used as a bleaching assistant, so that the bleached waste paper deinking pulp has good strength, high whiteness and good whiteness stability, and the COD value in the bleaching waste liquid can be obviously reduced;

5. the invention can obviously reduce the pollution load of the bleaching waste liquid by improving the hydrogen peroxide bleaching process.

Drawings

FIG. 1 is a schematic process flow diagram of a process for deinking waste paper and bleaching with magnesium-based hydrogen peroxide according to the present invention.

Detailed Description

The following examples are presented to further illustrate the present invention and should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.