Purification system of electronic-grade potassium hydroxide
By designing an electronic grade potassium hydroxide purification system including a supercooled freezing crystallization device, supercooled and cooled by using a freezing solution of -10 to -20°C, the rapid burst crystallization of the potassium hydroxide solution is achieved, and the problems of slow crystal generation and mechanical scraping in the traditional crystallization process are solved, and efficient and stable potassium hydroxide purification is achieved.
Patent Information
- Application Number
- CN202421483696.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-26
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2034-06-26
AI Technical Summary
The existing cooling and crystal purification system has problems such as slow crystal generation, repeated wall adhesion, long crystallization time, and low product yield, and mechanical scraping leads to equipment wear and maintenance time.
An electronic-grade potassium hydroxide purification system is designed, including a potassium hydroxide concentration device, a pre-cooling device, a pre-filtration device, a supercooling freezing crystallization device and a solid-liquid separation device. By using a refrigerant from -10 to -20°C in a supercooled and freezing crystallization device to perform supercooling and cooling, rapid burst crystallization of the potassium hydroxide solution is achieved, avoiding long-term cooling and mechanical scraping during the traditional crystallization process.
It achieves high yield preparation of potassium hydroxide, shortens crystallization time, improves product purification efficiency, reduces equipment wear and maintenance time caused by mechanical scraping, and improves production efficiency.
Smart Images
Figure CN222765701U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of chemical production systems, and in particular to a purification system for electronic-grade potassium hydroxide. Background Art
[0002] Electronic grade potassium hydroxide is a kind of potassium hydroxide with high purity and excellent chemical stability, which is widely used in high-tech industries such as electronic components, semiconductor manufacturing, photovoltaics and integrated circuits.
[0003] At present, the most commonly used process flow for the purification of electronic-grade potassium hydroxide is: first, potassium hydroxide is prepared into potassium hydroxide solution, and then ion exchange, cooling and crystallization are used to remove heavy metals and sodium ions. Finally, potassium hydroxide crystals and mother liquor are separated by centrifuge, and the separated crystals are dissolved to obtain electronic-grade potassium hydroxide.
[0004] However, the existing cooling and crystallization purification systems mostly use cooling water at about 5-25°C to slowly cool down. As the temperature decreases, the solubility of potassium hydroxide decreases and crystals gradually precipitate, which takes a long time to crystallize. In addition, since KOH crystals form monohydrate, dihydrate, and tetrahydrate crystals according to the crystallization conditions, these hydrated crystals are very likely to stick to the wall and agglomerate on the heat exchange surface during the gradual crystallization process, affecting heat transfer, resulting in a low single crystallization yield, a large amount of treatment liquid consumed for purification, and low production efficiency.
[0005] In actual production, it is almost inevitable that the heat exchange surface will have varying degrees of wall sticking during the cooling and crystallization process, which not only affects the cooling and crystallization process, but also has an adverse corrosion effect on the equipment. The heat exchange surface crystal scraping method is further adopted. Due to the wear of the scraping parts caused by mechanical friction, the worn parts cannot fit tightly and sufficient crystal scraping cannot be achieved. To replace the scraping parts, the equipment must be completely stopped, cleaned, disassembled, replaced, installed, cleaned, and tested before it can be put into use again. The maintenance time is long, which is not conducive to the continuous and stable operation of the crystallization process. Moreover, in actual production, mechanical scraping cannot avoid the adverse effect on the fluidity of the crystal due to partial agglomeration. In order to ensure the crystallization efficiency, a low-temperature continuous / circulating crystallization method is adopted. During the continuous heat exchange process, the crystals gradually increase when the alkali solution flows, which is prone to blockage.
[0006] In order to solve the problems of slow crystal generation in traditional crystallization process, repeated wall adhesion requiring mechanical scraping, long crystallization time, low product yield, etc., the utility model provides a purification system for electronic grade potassium hydroxide. Utility Model Content
[0007] The utility model aims to provide a purification system for electronic-grade potassium hydroxide. By using the system, electronic-grade potassium hydroxide with stable quality can be prepared with high yield.
[0008] In order to solve the above technical problems, the utility model provides the following technical solutions:
[0009] An electronic grade potassium hydroxide purification system comprises a potassium hydroxide concentration device, a pre-cooling device, a pre-filtering device, a supercooling crystallization device and a solid-liquid separation device which are connected in sequence;
[0010] The supercooling freezing crystallization device comprises a crystallization chamber, wherein the crystallization chamber is provided with a freezing pipe for freezing the material in the crystallization chamber, and the freezing pipe is connected with a freezing liquid feed pipe; the freezing liquid feed pipe is used to transmit a freezing liquid at -10 to -20°C;
[0011] The pre-filtering device is a 0.4-1 micron filter membrane filter.
[0012] Furthermore, the freezing tube includes an inner cooling tube, an outer cooling tube and a jacket; the inner cooling tube is arranged inside the crystallization chamber, the jacket is arranged on the outer wall surface of the crystallization chamber, and the outer cooling tube is arranged between the jacket and the outer wall surface of the crystallization chamber and is arranged in contact with the outer wall surface of the crystallization chamber.
[0013] Furthermore, the external cooling pipe is also connected to a circulating water pipe that provides circulating water at 15-25°C.
[0014] Furthermore, the roughness of the inner wall of the crystallization chamber is Ra≤0.2.
[0015] Furthermore, the supercooling freezing crystallization device also includes a stirring device.
[0016] Furthermore, the stirring device is an axial flow stirring device.
[0017] Furthermore, the potassium hydroxide concentration device is a triple-effect concentration device.
[0018] Furthermore, the pre-cooling device is a kettle or storage tank with stirring and / or self-circulation.
[0019] Furthermore, the crystallization chamber is a single crystallization chamber type crystallizer.
[0020] Furthermore, it also includes a washing device and a dissolving device, the washing device is located between the solid-liquid separation device and the dissolving device, and the washing device is connected to the solid-liquid separation device and the dissolving device.
[0021] The technical solution of the embodiment of the utility model has at least the following advantages and beneficial effects:
[0022] 1. When using the purification system of the present application, the concentrated potassium hydroxide solution is cooled to 50-60° C., and the heterogeneous crystal nuclei are filtered out through a micron-level filter device to obtain a pre-purified potassium hydroxide stock solution. The pre-purified potassium hydroxide stock solution is passed into a supercooled freezing crystallization device, and a -10--20° C. freezing liquid is passed through for supercooling. The potassium hydroxide solution crystals frozen at low temperature rapidly burst out crystallization in a short time, thereby avoiding the problems of slow crystal formation in the traditional crystallization process, repeated wall adhesion requiring mechanical scraping, long crystallization time, and low product yield.
[0023] 2. The utility model adopts a single crystal chamber crystallizer with bottom discharge, has no requirement for the lateral flow of materials, can allow a lower crystallization endpoint, and greatly improves the yield of a single purification product. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for use in the embodiments are briefly introduced below.
[0025] Figure 1 A purification system diagram of electronic grade potassium hydroxide provided in Example 1 of the utility model;
[0026] Figure 2 A structural diagram of a supercooling crystallization device provided in Example 1 of the utility model;
[0027] Icons: 10-potassium hydroxide concentration device, 20-pre-cooling device, 30-pre-filtration device, 40-supercooling crystallization device, 41-crystallization chamber, 42-internal cooling tube, 43-external cooling tube, 44-jacket, 45-stirring device, 50-solid-liquid separation device, 60-washing device, 70-dissolving device, 80-first freezing liquid feed pipe, 90-second freezing liquid feed pipe DETAILED DESCRIPTION
[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present utility model clearer, the technical solution in the embodiments of the present utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the present utility model.
[0029] Example 1
[0030] An electronic grade potassium hydroxide purification system comprises a potassium hydroxide concentration device 10, a pre-cooling device 20, a pre-filtering device 30, a supercooling crystallization device 40, and a solid-liquid separation device 50 which are connected in sequence;
[0031] The supercooling freezing crystallization device 40 includes a crystallization chamber 41, and the crystallization chamber 41 is equipped with a freezing pipe for freezing the material in the crystallization chamber 41, and the freezing pipe is connected to a freezing liquid feed pipe; the freezing liquid feed pipe is used to transmit a freezing liquid at -10 to -20°C;
[0032] The pre-filter device 30 is a 0.4-1 micron filter membrane filter.
[0033] Under certain conditions, KOH can be crystallized in bursts, and the KOH solution is quickly converted from a solution to a crystal system, and the precipitation of the entire crystal is achieved in a relatively short time. The rapid crystallization characteristics of burst crystallization shorten the crystallization process, thereby avoiding the long and unfavorable process of cooling-crystallization wall adhesion-scraping-cooling that is always accompanied by the slow and continuous cooling process of traditional production.
[0034] Since the purified raw material is industrial-grade KOH, it contains a lot of mechanical particle impurities and metal hydroxide micelles (such as some copper, iron, nickel, titanium, etc.). These particles and metal micelles will become heterogeneous crystal nuclei in the KOH crystallization process. Too many heterogeneous crystal nuclei will be unfavorable for the formation of supersaturated KOH solution and the realization of rapid short-term burst crystallization of supercooled frozen crystallization, so they must be removed. The pre-filter device 30 of the present application uses a 0.4-1 micron filter membrane filter to purify the particles below 1 micron in the potassium hydroxide stock solution to ≤500pcs / ml, preferably ≤300pcs / ml.
[0035] The filtration of the potassium hydroxide stock solution requires extra attention. Too high a temperature may cause the filter element / membrane to swell or even fail, resulting in poor filtration effect and failure to meet the supercooling and freezing crystallization requirements. However, if the temperature is too low, crystals may precipitate during filtration and block the filtration equipment and pipelines. Therefore, according to the concentration of the processed liquid, the pre-cooling device 20 pre-cools the potassium hydroxide concentrate to a temperature range suitable for filtration. Ideally, the temperature is generally 50 to 80°C.
[0036] The temperature of the freezing liquid determines the heat exchange rate. If the rate is too slow, the possibility of local crystallization in the cooling process increases. The freezing liquid temperature selected by the utility model is -10 to -20°C. This temperature is conducive to the rapid formation of a supercooled saturated potassium hydroxide solution and avoids local crystallization. In particular, this temperature is conducive to obtaining potassium hydroxide crystals with a higher yield.
[0037] The freezing pipe includes an inner cooling pipe 42, an outer cooling pipe 43 and a jacket 44; the inner cooling pipe 42 is arranged inside the crystallization chamber 41, the jacket 44 is sleeved on the outer wall of the crystallization chamber 41, and the outer cooling pipe 43 is arranged between the jacket 44 and the outer wall of the crystallization chamber 41 and adheres to the outer wall of the crystallization chamber 41.
[0038] The inner cooling tube 42 is connected to the first refrigerant liquid feed tube 80, and the outer cooling tube 43 is connected to the second refrigerant liquid feed tube 90. By simultaneously introducing refrigerant liquid into the inner cooling tube 42 and the outer cooling tube 43, the liquid in the crystallization chamber 41 can be quickly cooled, thereby achieving explosive crystallization.
[0039] The external cooling pipe 43 is also connected to a circulating water pipe that provides circulating water at 15-25°C.
[0040] After the burst crystallization is completed, further cooling will help the crystals grow further, which is beneficial to improving the purification yield. At the same time, since the system viscosity increases after the burst crystallization, the external cooling tube 43 is also connected to the circulating water pipe that provides 15-25°C circulating water. After the burst crystallization is completed, the crystallization system is further cooled to avoid local adhesion of the crystals to the wall.
[0041] The inner wall roughness of the crystallization chamber 41 is Ra≤0.2.
[0042] The inner wall of the crystallizer in contact with the potassium hydroxide liquid should also be as smooth as possible to avoid mechanically induced crystallization. In the present utility model, the inventors found that the roughness of the inner wall of the crystallizer Ra≤0.2 can better avoid mechanically induced crystallization.
[0043] The supercooling freezing crystallization device 40 further includes a stirring device 45 .
[0044] Stirring during the freezing crystallization process can assist the system in rapid heat transfer and cooling, but it will also cause the solutions to collide to form crystal nuclei. Therefore, it is necessary to assist heat transfer and cooling while suppressing their collision to form crystal nuclei. After long-term research, the stirring rate should be kept low, generally at 0 to 15 r / min, preferably 5 to 10 r / min.
[0045] The stirring device 45 is an axial flow stirring device.
[0046] The potassium hydroxide concentration device 10 is a triple-effect concentration device.
[0047] The pre-cooling device 20 is a kettle or storage tank with stirring and / or self-circulation.
[0048] The crystallization chamber 41 is a single crystallization chamber type crystallizer.
[0049] The device further includes a washing device 60 and a dissolving device 70 . The washing device 60 is located between the solid-liquid separation device 50 and the dissolving device 70 . The washing device 60 is connected to the solid-liquid separation device 50 and the dissolving device 70 .
[0050] The washing device 60 and the dissolving device 70 are used to wash and dissolve the crystals after solid-liquid separation.
[0051] The working principle of the utility model is as follows: a potassium hydroxide concentration device 10 concentrates 30-48% industrial potassium hydroxide into 53-58% industrial-grade potassium hydroxide concentrated liquid; a pre-cooling device 20 pre-cools the 53-58% industrial-grade potassium hydroxide concentrated liquid to 50-80°C with circulating water to obtain a potassium hydroxide stock solution; a pre-filtering device 30 pre-filters the potassium hydroxide stock solution to remove heterogeneous crystal nuclei to obtain a pre-purified potassium hydroxide stock solution; the pre-purified potassium hydroxide stock solution is passed into a supercooled freezing crystallization device 40, and a -10--20°C freezing liquid is passed through to supercool and cool to burst crystallization to obtain a potassium hydroxide-containing crystal system; after burst crystallization, the intermediate crystal system is continuously cooled to 20-30°C with 15-25°C circulating water to obtain a final crystal system; the final crystal system is sent to a solid-liquid separation device 50 for solid-liquid separation, and then enters a washing device 60 and a dissolving device 70, and the crystals are washed and dissolved to obtain an electronic-grade potassium hydroxide solution, and the mother liquor is returned to the industrial potassium hydroxide production system.
[0052] In summary, by adopting the electronic-grade potassium hydroxide purification system of the present application, electronic-grade potassium hydroxide with stable quality can be prepared with high yield.
Claims
1. A purification system for electronic grade potassium hydroxide, characterized in that: It includes a potassium hydroxide concentration device, a pre-cooling device, a pre-filtration device, a supercooling crystallization device and a solid-liquid separation device which are connected in sequence; The supercooling freezing crystallization device comprises a crystallization chamber, wherein the crystallization chamber is provided with a freezing pipe for freezing the material in the crystallization chamber, and the freezing pipe is connected with a freezing liquid feed pipe; the freezing liquid feed pipe is used to transmit a freezing liquid at -10 to -20°C; The pre-filtering device is a 0.4-1 micron filter membrane filter.
2. The purification system of electronic grade potassium hydroxide according to claim 1, characterized in that: The freezing pipe includes an inner cooling pipe, an outer cooling pipe and a jacket; the inner cooling pipe is arranged inside the crystallization chamber, the jacket is arranged on the outer wall surface of the crystallization chamber, and the outer cooling pipe is arranged between the jacket and the outer wall surface of the crystallization chamber and is arranged in contact with the outer wall surface of the crystallization chamber.
3. The purification system of electronic grade potassium hydroxide according to claim 2, characterized in that: The external cooling pipe is also connected to a circulating water pipe that provides circulating water at 15-25°C.
4. The purification system of electronic grade potassium hydroxide according to claim 1, characterized in that: The inner wall roughness of the crystallization chamber Ra≤0.
2.
5. The electronic grade potassium hydroxide purification system according to any one of claims 1 to 4, characterized in that: The supercooling freezing crystallization device also includes a stirring device.
6. The purification system of electronic grade potassium hydroxide according to claim 5, characterized in that: The stirring device is an axial flow stirring device.
7. The electronic grade potassium hydroxide purification system according to any one of claims 1 to 4, characterized in that: The potassium hydroxide concentrator is a triple-effect concentrator.
8. The electronic grade potassium hydroxide purification system according to any one of claims 1 to 4, characterized in that: The pre-cooling device is a kettle or storage tank with stirring and / or self-circulation.
9. The electronic grade potassium hydroxide purification system according to any one of claims 1 to 4, characterized in that: The crystallization chamber is a single crystallization chamber type crystallizer.
10. The electronic grade potassium hydroxide purification system according to any one of claims 1 to 4, characterized in that: It also includes a washing device and a dissolving device. The washing device is located between the solid-liquid separation device and the dissolving device, and the washing device is connected to the solid-liquid separation device and the dissolving device.