阅读说明：本技术 一种粘胶纤维酸浴蒸发制取元明粉的方法 (Method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose ) 是由 付敏波 姜术丹 摆生俊 兰伟宝 高磊 彭善俊 徐朝辉 张文涛 于 2020-11-25 设计创作，主要内容包括：本发明涉及粘胶纤维生产技术领域,具体涉及一种粘胶纤维酸浴蒸发制取元明粉的方法。所述一种粘胶纤维酸浴蒸发制取元明粉的方法,包括以下步骤：将所述酸浴预处理液进行第一次减压蒸发,并进行第一次降温析晶,过滤,得十水硫酸钠粗品；将所述十水硫酸钠粗品用水复溶得硫酸钠复溶溶液,在所述硫酸钠复溶溶液中加入新配制的活性炭双氧水处理液,升温搅拌后过滤得硫酸钠纯化液；所述硫酸钠纯化液进行第二次减压蒸发,并进行第二次降温析晶,晶体用饱和硫酸钠溶液洗涤,得十水硫酸钠纯品；所述十水硫酸钠纯品进行干燥得到元明粉。通过本发明的方法所制取的元明粉纯度和白度更高,锌含量和水不溶性物质含量更低。(The invention relates to the technical field of viscose fiber production, in particular to a method for preparing anhydrous sodium sulphate by viscose fiber acid bath evaporation. The method for preparing anhydrous sodium sulphate by viscose acid bath evaporation comprises the following steps: carrying out first reduced pressure evaporation on the acid bath pretreatment liquid, carrying out first cooling crystallization, and filtering to obtain a sodium sulfate decahydrate crude product; redissolving the crude sodium sulfate decahydrate with water to obtain a sodium sulfate redissolution, adding a newly prepared active carbon hydrogen peroxide treatment solution into the sodium sulfate redissolution, heating, stirring and filtering to obtain a sodium sulfate purified solution; carrying out secondary reduced pressure evaporation on the sodium sulfate purified solution, carrying out secondary cooling crystallization, and washing crystals with a saturated sodium sulfate solution to obtain a pure sodium sulfate decahydrate product; and drying the pure sodium sulfate decahydrate to obtain anhydrous sodium sulphate. The anhydrous sodium sulphate prepared by the method has higher purity and whiteness, and lower zinc content and water-insoluble substance content.)

1. A method for preparing anhydrous sodium sulphate by viscose acid bath evaporation is characterized by comprising the following steps:

1) pretreatment: carrying out aeration and filtration pretreatment on an acid bath for viscose spinning to obtain an acid bath pretreatment solution;

2) primary evaporation and crystallization: carrying out first reduced pressure evaporation on the acid bath pretreatment liquid, carrying out first cooling crystallization, and filtering to obtain a sodium sulfate decahydrate crude product;

3) redissolving and purifying: redissolving the crude sodium sulfate decahydrate with water to obtain a sodium sulfate redissolution, adding a newly prepared active carbon hydrogen peroxide treatment solution into the sodium sulfate redissolution, heating, stirring and filtering to obtain a sodium sulfate purified solution;

4) and (3) recrystallization: carrying out secondary reduced pressure evaporation on the sodium sulfate purified solution, carrying out secondary cooling crystallization, and washing crystals with a saturated sodium sulfate solution to obtain a pure sodium sulfate decahydrate product;

5) and (3) drying: and drying the pure sodium sulfate decahydrate to obtain anhydrous sodium sulphate.

2. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers according to claim 1, wherein the active carbon hydrogen peroxide treatment solution in the step 3) is 10-15% of the volume of the sodium sulphate redissolution.

3. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers according to claim 1 or 2, wherein the preparation method of the activated carbon hydrogen peroxide solution in the step 3) is to add activated carbon into the hydrogen peroxide solution and stir the solution for 20 to 30min at 50 to 60 ℃.

4. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers as claimed in claim 3, wherein the concentration of the hydrogen peroxide solution is 30-40%, and the mass ratio of the activated carbon to the hydrogen peroxide solution is 2-4: 10.

5. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers as claimed in claim 3, wherein the activated carbon is coconut shell activated carbon with a particle size of 0.4-3 mm.

6. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers as claimed in claim 1, wherein the temperature of the first reduced pressure evaporation in step 2) is 60-70 ℃ and the vacuum degree is 2 x 10⁴Pa—8×10⁴Pa；

And/or the first reduced pressure evaporation is carried out until the concentration is 1/2-3/4 of the volume of the acid bath pretreatment liquid;

and/or the temperature of the first cooling crystallization in the step 2) is 15-20 ℃.

7. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers according to claim 1, wherein the mass concentration of sodium sulphate in the redissolution solution in the step 3) is 35-40%; and/or the temperature of the reconstitution is 40-50 ℃.

8. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers as claimed in claim 1, wherein the temperature-raising stirring in step 3) is stirring at 300 rpm/min to 500rpm/min at 40-50 ℃ for 30-40 min.

9. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers as claimed in claim 1, wherein the temperature of the second reduced pressure evaporation in the step 4) is 60-70 ℃, and the vacuum degree is 2 x 10⁴Pa—8×10⁴Pa；

And/or the second reduced pressure evaporation in the step 4) needs to be concentrated to 3/5-3/4 of the volume of the sodium sulfate purified liquid;

and/or the temperature of the second cooling crystallization in the step 4) is firstly cooled to 40-50 ℃, and is kept for 20-30 min; then cooling to 15-20 ℃ for crystallization until crystallization is complete.

10. The method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fiber as claimed in claim 1, wherein the drying in step 5) is performed at 120-150 ℃ for 12-14 h.

Technical Field

The invention relates to the technical field of viscose fiber production, in particular to a method for preparing anhydrous sodium sulphate by viscose fiber acid bath evaporation.

Background

The viscose fiber acid bath mainly comprises a solution prepared from sulfuric acid, sodium sulfate and zinc sulfate, which can enable viscose to carry out solidification spinning, and is an important step of viscose fiber production, the content of each component in the acid bath, the clarity and cleanliness of the solution, the temperature and the like are critical to the quality of viscose fibers, a large amount of sulfuric acid is consumed in the acid bath process of the viscose fibers to generate sodium sulfate, the sodium sulfate can be separated out on the viscose fibers after saturation is achieved, the solidification time of the viscose is influenced, and the viscose solidification bath can simultaneously bring impurities such as sulfide, short fibers, glue blocks and the like, so that the solution is turbid, and therefore, the viscose acid bath needs to be recycled to remove excessive water, sodium sulfate and impurities. Acid bath evaporation is a method for removing redundant sodium sulfate and water which are frequently used in the prior art, anhydrous sodium sulphate can be prepared by the method, and in the prior art, no purification step is involved in the preparation process of the anhydrous sodium sulphate, so that water-insoluble impurities such as zinc sulfate, cellulose, sulfur-containing substances and the like are mixed in the recovered anhydrous sodium sulphate, and the product purity is poor.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers.

The technical scheme adopted by the invention for solving the technical problem is to provide a method for preparing anhydrous sodium sulphate by acid bath evaporation of viscose fibers, which comprises the following steps:

1) pretreatment: carrying out aeration and filtration pretreatment on an acid bath for viscose spinning to obtain an acid bath pretreatment solution;

2) primary evaporation and crystallization: carrying out first reduced pressure evaporation on the acid bath pretreatment liquid, carrying out first cooling crystallization, and filtering to obtain a sodium sulfate decahydrate crude product;

3) redissolving and purifying: redissolving the crude sodium sulfate decahydrate with water to obtain a sodium sulfate redissolution, adding a newly prepared active carbon hydrogen peroxide treatment solution into the sodium sulfate redissolution, heating, stirring and filtering to obtain a sodium sulfate purified solution;

4) and (3) recrystallization: carrying out secondary reduced pressure evaporation on the sodium sulfate purified solution, carrying out secondary cooling crystallization, and washing crystals with a saturated sodium sulfate solution to obtain a pure sodium sulfate decahydrate product;

5) and (3) drying: and drying the pure sodium sulfate decahydrate to obtain anhydrous sodium sulphate.

The recovery of sodium sulfate in the acid bath recovery can not only reduce the concentration of sodium sulfate in the acid bath, but also can produce anhydrous sodium sulfate. The sodium sulfate in the acid bath is prepared by adopting a conventional primary purification and crystallization method, impurities such as zinc sulfate, water-insoluble cellulose and sulfide are mixed in the obtained sodium sulfate, the purity and whiteness of the prepared anhydrous sodium sulphate are low due to the existence of the impurities, and the impurities such as the cellulose and the sulfide contained in the anhydrous sodium sulphate are easy to agglomerate, so that the granularity unevenness and the whiteness of the anhydrous sodium sulphate are poor. In order to improve whiteness and reduce impurities such as cellulose, sulfide and the like, the prior art usually adopts high temperature of over 800 ℃ for roasting, which needs to consume a large amount of heat energy and pollutes the atmosphere. In the invention, sodium sulfate obtained by crystallization is redissolved and purified by selecting the active carbon hydrogen peroxide treatment liquid, on one hand, the applicant finds that hydrogen peroxide can improve the adsorption capacity of active carbon on water-insoluble impurities and zinc in anhydrous sodium sulphate, and the anhydrous sodium sulphate has higher purity. On the other hand, the hydrogen peroxide can oxidize the low-valence sulfide in the sodium sulfide redissolution into sulfur, and remove sulfur-containing impurities in the anhydrous sodium sulphate by a filtering method.

In addition, the invention is provided with the steps of redissolution purification and recrystallization, the pH value of the sodium sulfate redissolution solution is obviously improved and is close to neutral compared with that of an acid bath, Zn2+ begins to precipitate under the condition, the settling speed of Zn2+ is accelerated in the presence of the active carbon hydrogen peroxide treatment solution in the solution, and the zinc content of the finally obtained anhydrous sodium sulphate is lower.

Further, the active carbon hydrogen peroxide solution treatment liquid in the step 3) is 10-15% of the volume of the sodium sulfate redissolution solution.

Further, the preparation method of the active carbon hydrogen peroxide solution in the step 3) comprises the steps of adding the active carbon into the hydrogen peroxide solution, and stirring for 20-30min at 50-60 ℃ to obtain the active carbon hydrogen peroxide solution.

Further, the concentration of the hydrogen peroxide solution is 30-40%, and the mass ratio of the activated carbon to the hydrogen peroxide solution is 2-4: 10.

Furthermore, the activated carbon is coconut shell activated carbon with the particle size of 0.4-3 mm.

Further, the temperature of the first decompression evaporation in the step 2) is 60-70 ℃, and the vacuum degree is 2 x 10⁴Pa—8×10⁴Pa；

And/or the first reduced pressure evaporation is carried out until the concentration is 1/2-3/4 of the volume of the acid bath pretreatment liquid;

and/or the temperature of the first cooling crystallization in the step 2) is 15-20 ℃.

Further, the mass concentration of sodium sulfate in the redissolution solution in the step 3) is 35-40%; and/or the temperature of the reconstitution is 40-50 ℃.

Further, the heating and stirring in the step 3) is carried out at the temperature of 40-50 ℃ and at the speed of 300-500rpm/min for 30-40 min.

Further, the temperature of the second reduced pressure evaporation in the step 4) is 60-70 ℃, and the vacuum degree is 2 x 10⁴Pa—8×10⁴Pa；

And/or the second reduced pressure evaporation in the step 4) needs to be concentrated to 3/5-3/4 of the volume of the sodium sulfate purified liquid;

and/or the temperature of the second cooling crystallization in the step 4) is firstly cooled to 40-50 ℃, and is kept for 20-30 min; then cooling to 15-20 ℃ for crystallization until crystallization is complete.

Further, the drying in the step 5) is carried out at the temperature of 120-150 ℃ for 12-14 h.

Compared with the prior art, the invention has the following beneficial effects: the anhydrous sodium sulphate is redissolved and purified by using the active carbon hydrogen peroxide treatment solution; on the one hand, the applicant finds that the hydrogen peroxide can improve the adsorption capacity of the activated carbon on water-insoluble impurities and zinc in the anhydrous sodium sulphate, and the anhydrous sodium sulphate is higher in purity. On the other hand, the hydrogen peroxide can oxidize the low-valence sulfide in the sodium sulfide redissolution into sulfur, and remove sulfur-containing impurities in the anhydrous sodium sulphate by a filtering method.

Detailed Description

The experimental procedures in the following examples are conventional unless otherwise specified. The raw materials in the following examples are all commercially available products and are commercially available, unless otherwise specified. The present invention is described in further detail below with reference to examples:

example 1

The embodiment provides a method for preparing anhydrous sodium sulphate by viscose acid bath evaporation, which comprises the following steps:

1) pretreatment: carrying out acid bath aeration treatment on the viscose for viscose spinning to remove most of sulfide in the viscose, and filtering to remove most of cellulose and solid impurities to obtain acid bath pretreatment liquid;

2) primary evaporation and crystallization: the acid bath pretreatment solution was heated at 65 ℃ under a vacuum of 4X 10⁴Carrying out first reduced pressure evaporation under Pa to 1/2 with the volume equal to the original volume; then crystallizing for 3h at 18 ℃, and filtering to obtain a sodium sulfate decahydrate crude product;

3) redissolving and purifying: adding water into a sodium sulfate decahydrate crude product, dissolving at 45 ℃ to prepare a sodium sulfate redissolution with the mass concentration of 38%, adding a newly prepared activated carbon hydrogen peroxide treatment solution with the volume of 15% of the sodium sulfate redissolution into the sodium sulfate redissolution (wherein the preparation method of the activated carbon hydrogen peroxide solution is to add activated carbon into a 35% hydrogen peroxide solution, stirring at 55 ℃ for 25min to obtain the sodium sulfate purified solution, wherein the mass ratio of the activated carbon to the hydrogen peroxide solution is 3:10, and the activated carbon is coconut shell activated carbon with the particle size of 0.4-3 mm), stirring at 45 ℃ and 400rpm/min for 35min, and filtering to obtain a sodium sulfate purified solution;

4) and (3) recrystallization: sodium sulfate purified solution at 65 deg.C and vacuum degree of 4 × 10⁴Carrying out second reduced pressure evaporation under Pa to 3/4 of the original volume, cooling to 45 ℃, and keeping for 25 min; then cooling to 18 ℃ for crystallization for 5h, and washing the obtained crystal with a saturated sodium sulfate solution to obtain a pure sodium sulfate decahydrate product;

5) and (3) drying: drying the pure sodium sulfate decahydrate at 135 ℃ for 13h to obtain anhydrous sodium sulfate.

Example 2

The embodiment provides a method for preparing anhydrous sodium sulphate by viscose acid bath evaporation, which comprises the following steps:

1) pretreatment: carrying out aeration treatment on an acid bath for viscose spinning to remove most of sulfide in the acid bath, and filtering to remove most of cellulose and solid impurities to obtain an acid bath pretreatment solution;

2) primary evaporation and crystallization: the acid bath pretreatment liquid was heated at 60 ℃ under a vacuum of 2X 10⁴Concentrating under Pa to 3/4 of the original volume; then crystallizing for 2h at 15 ℃, and filtering to obtain a crude product of sodium sulfate decahydrate;

3) redissolving and purifying: adding water into a sodium sulfate decahydrate crude product, dissolving at 45 ℃ to prepare a sodium sulfate redissolution with the mass concentration of 40%, adding a newly prepared activated carbon hydrogen peroxide treatment solution with the volume of 13% of the sodium sulfate redissolution into the sodium sulfate redissolution (wherein the preparation method of the activated carbon hydrogen peroxide solution is to add activated carbon into a 30% hydrogen peroxide solution, stirring at 60 ℃ for 20min to obtain the sodium sulfate sodium hydrogen peroxide solution, wherein the mass ratio of the activated carbon to the hydrogen peroxide solution is 4:10, and the activated carbon is coconut shell activated carbon with the particle size of 0.4-3 mm), stirring at 40 ℃ and 500rpm/min for 40min, and filtering to obtain a sodium sulfate purified solution;

4) and (3) recrystallization: sodium sulfate purified solution at 70 deg.C and vacuum degree of 4 × 10⁴Concentrating under Pa to 3/5 of the original volume, and then cooling to 40 ℃ for 20 min; continuously cooling to 20 ℃ for crystallization for 6h, and washing the obtained crystal with a saturated sodium sulfate solution to obtain a pure sodium sulfate decahydrate product;

5) and (3) drying: drying the pure sodium sulfate decahydrate at 135 ℃ for 14h to obtain anhydrous sodium sulfate.

Example 3

The embodiment provides a method for preparing anhydrous sodium sulphate by viscose acid bath evaporation, which comprises the following steps:

1) pretreatment: carrying out acid bath aeration treatment on the viscose for viscose spinning to remove most of sulfide in the viscose, and filtering to remove most of cellulose and solid impurities to obtain acid bath pretreatment liquid;

2) primary evaporation and crystallization: the acid bath pretreatment solution was heated at 70 ℃ under a vacuum of 4X 10⁴1/2 concentrated to the original volume under Pa; then crystallizing for 3h at 20 ℃, and filtering to obtain a sodium sulfate decahydrate crude product;

3) redissolving and purifying: adding water into a sodium sulfate decahydrate crude product, dissolving at 50 ℃ to prepare a sodium sulfate redissolution with the mass concentration of 40%, adding a newly prepared active carbon hydrogen peroxide solution with the volume of 10% of the sodium sulfate redissolution into the sodium sulfate redissolution (wherein the preparation method of the active carbon hydrogen peroxide solution is to add active carbon into the hydrogen peroxide solution with the concentration of 40%, stirring at 50 ℃ for 30min to obtain the active carbon hydrogen peroxide solution, wherein the mass ratio of the active carbon to the hydrogen peroxide solution is 4:10, and the active carbon is coconut shell active carbon with the particle size of 0.4-3 mm), stirring at 50 ℃ and 500rpm/min for 40min, and filtering to obtain a sodium sulfate purified solution;

4) and (3) recrystallization: sodium sulfate purified solution at 70 deg.C and vacuum degree of 2 × 10⁴Concentrating under Pa to 3/4 of original volume, cooling to 45 deg.C, and maintaining for 25 min; then cooling to 20 ℃ for crystallization for 4h, and washing the obtained crystal with a saturated sodium sulfate solution to obtain a pure sodium sulfate decahydrate product;

5) and (3) drying: drying the pure sodium sulfate decahydrate at 135 ℃ for 14h to obtain anhydrous sodium sulfate.

Example 4

The embodiment provides a method for preparing anhydrous sodium sulphate by viscose acid bath evaporation, which comprises the following steps:

1) pretreatment: carrying out acid bath aeration treatment on the viscose for viscose spinning to remove most of sulfide in the viscose, and filtering to remove most of cellulose and solid impurities to obtain acid bath pretreatment liquid;

2) primary evaporation and crystallization: the acid bath pretreatment solution was heated at 65 ℃ under a vacuum of 4X 10⁴Carrying out first reduced pressure evaporation under Pa to 1/2 with the volume equal to the original volume; then crystallizing for 3h at 18 ℃, and filtering to obtain a sodium sulfate decahydrate crude product;

3) redissolving and purifying: adding water into a sodium sulfate decahydrate crude product, dissolving at 45 ℃ to prepare a sodium sulfate redissolution with the mass concentration of 40%, adding a newly prepared activated carbon hydrogen peroxide treatment solution with the volume of 13% of the sodium sulfate redissolution into the sodium sulfate redissolution (wherein the preparation method of the activated carbon hydrogen peroxide solution is to add activated carbon into a 30% hydrogen peroxide solution, stirring at 60 ℃ for 20min to obtain the sodium sulfate sodium hydrogen peroxide solution, wherein the mass ratio of the activated carbon to the hydrogen peroxide solution is 4:10, and the activated carbon is coconut shell activated carbon with the particle size of 0.4-3 mm), stirring at 40 ℃ and 500rpm/min for 40min, and filtering to obtain a sodium sulfate purified solution;

4) and (3) recrystallization: sodium sulfate purified solution at 70 deg.C and vacuum degree of 4 × 10⁴Concentrating under Pa to 3/5 of the original volume, and then cooling to 40 ℃ for 20 min; continuously cooling to 20 ℃ for crystallization for 6h, and washing the obtained crystal with a saturated sodium sulfate solution to obtain a pure sodium sulfate decahydrate product;

5) and (3) drying: drying the pure sodium sulfate decahydrate at 135 ℃ for 14h to obtain anhydrous sodium sulfate.

Comparative example

The difference from example 1 is that the hydrogen peroxide in the activated carbon hydrogen peroxide solution treatment liquid is replaced by equal amount of water, the anhydrous sodium sulphate is prepared by the steps of example 1 in the rest steps, the anhydrous sodium sulphate mass fraction, the water insoluble mass fraction, the zinc mass fraction and the whiteness degree (R457) purity of the anhydrous sodium sulphate prepared in examples 1-4 and comparative example are measured, and the results are shown in Table 1,

TABLE 1 Yuan Min powder Mass determination results

As can be seen from Table 1, the glauber salt prepared in examples 1-4 of the present application has better mass fraction of sodium sulfate and whiteness and lower mass fraction of water-insoluble substances and zinc than the comparative examples, which shows that the hydrogen peroxide solution treating solution using activated carbon in the method of the present invention can better remove water-insoluble substances and zinc in the acid bath of viscose fibers than the activated carbon, so that the glauber salt has higher purity and whiteness and lower impurity content.

Finally, it should be emphasized that the above-described preferred embodiments of the present invention are merely examples of implementations, rather than limitations, and that many variations and modifications of the invention are possible to those skilled in the art, without departing from the spirit and scope of the invention.