阅读说明：本技术 一种电子级氢氧化钾的制备方法 (Preparation method of electronic-grade potassium hydroxide ) 是由 刘鹏程 郑钰钏 罗小容 张天兰 于 2021-10-28 设计创作，主要内容包括：本发明涉及一种电子级氢氧化钾的制备方法,其主要包含溶液配制,冷却结晶,离心,溶解过滤步骤。与现有技术相比,本发明具有操作简单、成本低、可大量生产等优点。得到的最终氢氧化钾产品纯度高,其中Ca离子含量低于300ppb,Mg离子含量低于50ppb,Fe离子含量低于100ppb,Ni离子含量低于1ppb,Na离子含量在100ppm以内。(The invention relates to a preparation method of electronic-grade potassium hydroxide, which mainly comprises the steps of solution preparation, cooling crystallization, centrifugation, dissolution and filtration. Compared with the prior art, the method has the advantages of simple operation, low cost, mass production and the like. The obtained final potassium hydroxide product has high purity, wherein the content of Ca ions is less than 300ppb, the content of Mg ions is less than 50ppb, the content of Fe ions is less than 100ppb, the content of Ni ions is less than 1ppb, and the content of Na ions is within 100 ppm.)

1. The preparation method of the electronic-grade potassium hydroxide is characterized by comprising the following steps of:

(1) taking industrial-grade potassium hydroxide solution and potassium hydroxide flake caustic soda, stirring and dissolving to prepare 50-75% of potassium hydroxide solution;

(2) cooling the potassium hydroxide solution to 30-45 ℃ to obtain potassium hydroxide crystals;

(3) carrying out centrifugal separation on the material obtained in the step (2);

(4) and dissolving the centrifuged potassium hydroxide crystals in pure water to prepare potassium hydroxide solutions with different concentrations, and filtering the potassium hydroxide solutions through a precision filter to obtain the electronic-grade potassium hydroxide solution.

2. The method for preparing electronic grade potassium hydroxide according to claim 1, wherein the concentration of the prepared potassium hydroxide solution in the step (1) is 50-75%, preferably 60-75%, and most preferably 65-70%.

3. The method for preparing electronic grade potassium hydroxide according to claim 1, wherein the crystallization temperature of the potassium hydroxide in the step (2) is 30-45 ℃, preferably 35-40 ℃.

4. The method for preparing electronic-grade potassium hydroxide according to claim 1, wherein the temperature of the circulating water is reduced in the temperature reduction process in the step (2), and the temperature of the circulating water is 5-25 ℃, preferably 10-20 ℃, and most preferably 10-15 ℃.

5. The method for preparing electronic grade potassium hydroxide according to claim 1, wherein in the centrifugal separation in the step (3), ultrapure water is used for atomizing and spraying the potassium hydroxide during the centrifugal separation.

6. The method according to claim 1, wherein the precision filter in the step (4) has a filtration precision of 0.2-2.0 μm, preferably 1.0-2.0 μm, and most preferably 1.2-1.5 μm.

7. The method of claim 1, wherein the preparation vessel in step (1) is made of stainless steel, preferably ceramic, and most preferably PTFE-lined vessel.

8. The method for preparing electronic grade potassium hydroxide according to claim 1, wherein the mass fraction of potassium hydroxide in the industrial grade potassium hydroxide solution in the step (1) is 30-48%, and the purity of potassium hydroxide flake caustic soda is 90-95%.

9. The method according to any one of claims 1 to 8, wherein the electronic-grade potassium hydroxide is a solution or a solid.

10. The preparation method of the electronic-grade potassium hydroxide according to any one of claims 1 to 8, wherein the mass fraction of the potassium hydroxide in the prepared potassium hydroxide solution is 48%, the content of Ca ions in the solution is less than 300ppb, the content of Mg ions is less than 50ppb, the content of Fe ions is less than 100ppb, the content of Ni ions is less than 1ppb, and the content of Na ions is less than 100 ppm.

Technical Field

The invention relates to the field of chemical manufacturing, in particular to a preparation method of electronic-grade potassium hydroxide.

Background

With the development of high and new electronic circuit boards in the world, the global demand for high-purity electronic grade potassium hydroxide is continuously rising. Technical grade potassium hydroxide has not met the requirements. Therefore, it is necessary to purify industrial-grade potassium hydroxide to improve the quality.

Chinese patent 96110804.5 discloses a method for producing high-purity potassium hydroxide by using a fluorine-containing cation exchange membrane and hydrolyzing a potassium chloride solution using the cation exchange membrane as a diaphragm, which is large in energy consumption and high in cost. Patent 200810147324.2 relates to a method for extracting an aqueous solution of potassium hydroxide rich in silicon impurities by using a lower alcohol. The method only aims at the impurity silicon, and does not involve the removal of other impurity ions. Patent 201010576437.1 discloses a method for dissolving potassium metaborate in aqueous solution of sodium hydroxide, heating and refluxing, and separating solid from liquid to obtain solid potassium hydroxide, wherein the method has the disadvantages of complicated process, high energy consumption and no concern about the purity of potassium hydroxide. Patent 201410290942.8 discloses a continuous production method of high-purity potassium hydroxide aqueous solution, in which the potassium hydroxide solution is sequentially passed through chelating resin, cation exchange resin, anion exchange resin, electrodialysis and multi-stage filter element circulation system to remove impurities, and the process is complicated in steps and high in process cost. In patent CN202010747995.3, the process of preparing electronic-grade potassium hydroxide by electrolyzing purified potassium chloride has the problems of complex process route, poor treatment of acid waste brine and the like.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a preparation method which is simple to operate, low in cost and capable of producing electronic-grade potassium hydroxide in a large scale.

The purpose of the invention can be realized by the following technical scheme:

a preparation method of electronic-grade potassium hydroxide comprises the following steps:

(1) taking industrial-grade potassium hydroxide solution and potassium hydroxide flake caustic soda, stirring and dissolving to prepare 50-75% of potassium hydroxide solution;

(2) cooling the potassium hydroxide solution to 30-45 ℃ to obtain potassium hydroxide crystals;

(3) carrying out centrifugal separation on the material in the step (2);

(4) and (4) dissolving the potassium hydroxide crystals in pure water after centrifugation to prepare potassium hydroxide solutions with different concentrations, and filtering the potassium hydroxide solutions through a precision filter to obtain the high-purity potassium hydroxide solution.

The standards for the electronic grade potassium hydroxide solution are as follows:

TABLE 1 requirements

Note: the standard is the electronic-grade potassium hydroxide solution enterprise standard (Q/82723425-3.02-2020) of Chengduhua thawing chemical company Limited, and the electronic-grade potassium hydroxide solution prepared in the invention is used as the standard.

According to the technical scheme of the invention, the electronic-grade potassium hydroxide product can be obtained, wherein the potassium hydroxide solution with the potassium hydroxide mass fraction of 48% has the Ca ion content of less than 300ppb, the Mg ion content of less than 50ppb, the Fe ion content of less than 100ppb, the Ni ion content of less than 1ppb and the Na ion content of less than 100 ppm.

Further, the concentration of the prepared potassium hydroxide solution in the step (1) is 50-75%, preferably 60-75%, and most preferably 65-70%.

In the invention, as a preferable scheme, the potassium hydroxide solution in the step (1) is prepared to have the mass fraction of potassium hydroxide of 65-70%, so that the potassium hydroxide is beneficial to crystallization.

Further, in order to ensure the yield, the temperature of the potassium hydroxide solution in the step (2) is 30-45 ℃, and preferably 35-40 ℃.

In the present invention, the crystallization temperature of the potassium hydroxide solution in the step (2) is preferably 35 to 40 ℃ in order that the yield of potassium hydroxide crystals is good at this temperature.

In the invention, as a preferred scheme, the reason why the circulating water is adopted to cool the potassium hydroxide solution in the step (2) is that the water has larger specific heat capacity, the raw materials are easy to obtain, and the purpose of reducing the cost can be achieved by adopting the circulating water mode.

Further, in the centrifugal drying in the step (3), a spraying device is added to the centrifugal machine, and ultrapure water is adopted to atomize and spray the potassium hydroxide during centrifugation.

In the invention, as a preferred scheme, the aim of atomizing and spraying the potassium hydroxide by adopting ultrapure water during centrifugation in the step (3) is to accelerate the mass transfer process and quickly take away impurities when the spray and the crystals are in a hypergravity state, and meanwhile, the yield loss of the crystals is also reduced, and better washing effect and yield effect can be ensured.

Further, the precision filter in the step (4) has a filtering precision of 0.2-2.0 μm, preferably 1.0-2.0 μm, and most preferably 1.2-1.5 μm.

Further, the preparation vessel in step (1) is generally made of stainless steel, preferably made of ceramic, and most preferably lined with teflon.

In the invention, the preferable scheme is that the tetrafluoro lined container is selected to avoid introducing new impurities due to the material of the container.

Further, the mass fraction of the potassium hydroxide in the industrial-grade potassium hydroxide solution in the step (1) is 30-48%, and the purity of the potassium hydroxide flake caustic soda is 90-95%.

In the invention, as a preferred scheme, the 65-70% potassium hydroxide solution prepared by using 30-48% potassium hydroxide solution and 90-95% potassium hydroxide flake caustic soda together has lower heat release temperature compared with the potassium hydroxide flake caustic soda directly dissolved by water, reduces cooling time, is beneficial to crystallization of the potassium hydroxide solution in the step (2), and thus achieves the purpose of improving preparation efficiency.

The invention has the beneficial effects that:

1. compared with the method for directly dissolving the caustic soda flakes by using water, the method for dissolving the caustic soda flakes by using the 30-48% caustic soda solution has the advantages that the heat release temperature is lower, the subsequent cooling energy consumption is lower, and the possibility that more impurities flow into the caustic soda flakes in the cooling crystallization process to cause overhigh impurities in the crystals can be avoided.

2. The traditional crystallization is to reduce the solution temperature, a freezing crystallization mode is adopted, the energy consumption is high, the concentration of the potassium hydroxide solution is increased to 50-75%, the concentration is high, crystallization can be carried out at normal temperature, the temperature of freezing crystallization is not required to be reached, circulating water is adopted for cooling in the crystallization process, and the cost is saved.

3. In the centrifugal process, adopt ultrapure water to be vaporific to spray, under centrifugal state, the spraying is in the hypergravity state with the crystal and can accelerates the mass transfer process, takes away impurity fast, also can reduce to the yield loss of crystal simultaneously, can guarantee better washing effect and yield effect.

4. In the whole process, no complexing agent is added, so that the complexing agent is prevented from being substituted into impurities again, and meanwhile, the cost can be saved.

5. The final potassium hydroxide product has high purity, wherein the content of Ca ions is less than 300ppb, the content of Mg ions is less than 50ppb, the content of Fe ions is less than 100ppb, the content of Ni ions is less than 1ppb, and the content of Na ions is within 100 ppm.

Detailed Description

The present invention will be described in detail with reference to specific examples.

Example 1

A preparation method of electronic-grade potassium hydroxide comprises the following steps:

(1) mixing industrial grade 30% potassium hydroxide solution and industrial grade 90% potassium hydroxide flake caustic soda, stirring and dissolving to prepare 65% potassium hydroxide solution (the sodium ion content is 2533ppm, the iron ion content is 310ppb, and the nickel ion content is 0.63 ppm);

(2) cooling the potassium hydroxide solution to 42 ℃ by introducing 10 ℃ cooling circulating water, and separating out potassium hydroxide hydrated crystals;

(3) collecting water and potassium hydroxide crystals and residual potassium hydroxide solution, carrying out centrifugal separation, and atomizing and spraying potassium hydroxide by adopting ultrapure water during centrifugation;

(4) and (4) adding the electronic-grade potassium hydroxide product obtained in the step (3) into pure water in proportion for dissolving, and not filtering.

After detection, the mass fraction of potassium hydroxide in the electronic-grade potassium hydroxide solution product is about 48%, the sodium ion content is lower than 50ppm, the nickel ion content is lower than 1ppm, the iron ion content is lower than 90ppb, the calcium ion content is lower than 600ppb, and the yield is 10%. The detailed data are shown in Table 1.

Example 2

A preparation method of electronic-grade potassium hydroxide comprises the following steps:

(1) mixing industrial grade 30% potassium hydroxide solution and industrial grade 90% potassium hydroxide flake caustic soda, stirring and dissolving to prepare 65% potassium hydroxide solution (the sodium ion content is 2533ppm, the iron ion content is 310ppb, and the nickel ion content is 0.63 ppm);

(2) cooling the potassium hydroxide solution to 38 ℃ by introducing 15 ℃ cooling circulating water, and separating out potassium hydroxide hydrated crystals;

(3) collecting water and potassium hydroxide crystals and residual potassium hydroxide solution, carrying out centrifugal separation, and atomizing and spraying potassium hydroxide by adopting ultrapure water during centrifugation;

(4) and (4) adding the electronic-grade potassium hydroxide product obtained in the step (3) into pure water according to a proportion for dissolving, and filtering by using a 1.2-micron filter membrane to obtain a high-purity potassium hydroxide solution.

After detection, the mass fraction of potassium hydroxide in the electronic-grade potassium hydroxide solution product is about 48%, the sodium ion content is lower than 50ppm, the nickel ion content is lower than 50ppb, the iron ion content is lower than 100ppb, the calcium ion content is lower than 300ppb, the magnesium ion content is lower than 50ppb, and the yield is 22%. The detailed data are shown in Table 1.

Example 3

A preparation method of electronic-grade potassium hydroxide comprises the following steps:

(1) mixing industrial grade 48% potassium hydroxide solution and industrial grade 95% potassium hydroxide flake caustic soda, stirring and dissolving to prepare 67% potassium hydroxide solution (sodium ion content 2400ppm, iron ion content 300ppb, nickel ion 0.85 ppm);

(2) cooling the potassium hydroxide solution to 38 ℃ by introducing 15 ℃ cooling circulating water, and separating out potassium hydroxide hydrated crystals;

(3) collecting water and potassium hydroxide crystals and residual potassium hydroxide solution, carrying out centrifugal separation, and atomizing and spraying potassium hydroxide by adopting ultrapure water during centrifugation;

(4) and (4) adding the electronic-grade potassium hydroxide product obtained in the step (3) into pure water according to a proportion for dissolving, and filtering by using a 0.8-micron filter membrane to obtain a high-purity potassium hydroxide solution.

After detection, the mass fraction of potassium hydroxide in the electronic-grade potassium hydroxide solution product is about 48%, the sodium ion content is lower than 20ppm, the nickel ion content is lower than 1ppb, the iron ion content is lower than 100ppb, the calcium ion content is lower than 200ppb, the magnesium ion content is lower than 50ppb, and the yield is 23%. The detailed data are shown in Table 1.

Comparative example 1

A preparation method of electronic-grade potassium hydroxide comprises the following steps:

(1) mixing industrial grade 30% potassium hydroxide solution and industrial grade 90% potassium hydroxide flake caustic soda, stirring and dissolving to prepare 70% potassium hydroxide solution (the sodium ion content is 2752ppm, the iron ion content is 200ppb, and the nickel ion content is 0.9 ppm);

(2) cooling the potassium hydroxide solution to 42 ℃ by circulating cooling water at 5 ℃, and separating out potassium hydroxide hydrated crystals;

(3) collecting water and potassium hydroxide crystals and residual potassium hydroxide solution, and performing centrifugal separation (without spraying);

(4) and (4) adding the potassium hydroxide product obtained in the step (3) into pure water according to a proportion for dissolving, and filtering by using a 2.0-micron filter membrane to obtain a potassium hydroxide solution.

After detection, the mass fraction of potassium hydroxide in the potassium hydroxide solution product is about 48%, the sodium ion content is lower than 800ppm, the calcium ion content is lower than 500ppb, the magnesium ion content is lower than 50ppb, and the yield is 11%. The detailed data are shown in Table 1.

Comparative example 2

A preparation method of electronic-grade potassium hydroxide comprises the following steps:

(1) taking industrial-grade 95% potassium hydroxide flake caustic soda, stirring and dissolving by pure water to prepare a 67% potassium hydroxide solution (the sodium ion content of the potassium hydroxide solution is 3000ppm, the iron ion content is 800ppb, and the nickel ion content is 0.85 ppm);

(2) cooling the potassium hydroxide solution to 38 ℃ by introducing 15 ℃ cooling circulating water, and separating out potassium hydroxide hydrated crystals;

(3) collecting water and potassium hydroxide crystals and residual potassium hydroxide solution, and performing centrifugal separation while spraying;

(4) and (4) adding the potassium hydroxide product obtained in the step (3) into pure water according to a certain proportion for dissolving, and filtering by using a 0.8-micron filter membrane to obtain a high-purity potassium hydroxide solution.

After detection, the mass fraction of potassium hydroxide in the potassium hydroxide solution product is about 48%, the sodium ion content is 350ppm, the nickel ion content is lower than 1ppb, the iron ion content is lower than 300ppb, the calcium ion content is lower than 200ppb, the magnesium ion content is lower than 50ppb, and the yield is 25%. The detailed data are shown in Table 1.

Comparative example 3

A preparation method of electronic-grade potassium hydroxide comprises the following steps:

(1) mixing industrial grade 48% potassium hydroxide solution and industrial grade 95% potassium hydroxide flake caustic soda, stirring and dissolving to prepare 50% potassium hydroxide solution (sodium ion content 2400ppm, iron ion content 300ppb, nickel ion 0.85 ppm);

(2) cooling the potassium hydroxide solution to 38 ℃ by introducing 15 ℃ cooling circulating water, and no crystal is separated out; then, the temperature is reduced by adopting freezing saline water at the temperature of 35 ℃ below zero, and a small amount of crystals are separated out;

(3) collecting water and potassium hydroxide crystals and residual potassium hydroxide solution, carrying out centrifugal separation, and atomizing and spraying potassium hydroxide by adopting ultrapure water during centrifugation;

(4) and (4) adding the potassium hydroxide product obtained in the step (3) into pure water according to a proportion for dissolving, and filtering by using a 0.8-micron filter membrane to obtain a potassium hydroxide solution.

After detection, the mass fraction of potassium hydroxide in the potassium hydroxide solution product is about 48%, the sodium ion content is 1500ppm, the nickel ion content is lower than 1ppb, the iron ion content is lower than 200ppb, the calcium ion content is lower than 200ppb, the magnesium ion content is lower than 50ppb, and the yield is 23%. The detailed data are shown in Table 1.

TABLE 1 test and comparison data sheet

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications can be made to the embodiments and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art can make improvements and modifications within the scope of the present invention based on the disclosure of the invention.