Aqueous silicon dioxide preparation device with solvent recovery function
By designing an aqueous silica preparation device with solvent recovery function, the problems of low purity of methanol and waste liquid treatment in the prior art are solved, and the high purity extraction and recycling of methanol are achieved, which reduces costs and saves process costs.
Patent Information
- Application Number
- CN202421783927.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-26
- Publication Date
- 2025-05-27
- Estimated Expiration
- 2034-07-26
AI Technical Summary
In the prior art, when preparing colloidal silica, the liquid output by the condenser contains methanol solvent and ammonia-rich solvent, resulting in low purity of methanol that can no longer be used, increasing the cost of raw materials and requiring the treatment of waste liquid.
A water-based silica preparation device with solvent recovery function was designed. Through the design of the methanol collection tank and the second reactor, and the improvement of the condenser connection structure, the high purity extraction and recycling of methanol were achieved.
Real-time recycling of methanol is realized, the cost of raw materials is reduced, the generation and treatment process of waste liquid is avoided, and the process cost is saved.
Smart Images
Figure CN222901100U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of semiconductors, relates to a preparation process of silicon dioxide, and particularly relates to a device for preparing aqueous silicon dioxide with a solvent recovery function. Background Technique
[0002] Colloidal silicon dioxide, also known as silica sol, is a dispersion liquid in which silicon dioxide particles are dispersed in water and is widely used in catalysts, coatings, precision casting, etc. In recent years, it has been widely used in fields such as chemical mechanical polishing (CMP). With the continuous development of semiconductor technology, higher quality requirements are put forward for colloidal silicon dioxide abrasives, especially purity requirements. There is a need for an ultra-high purity silica sol containing extremely small amounts of metal impurities, but the cost is required to be lower and lower.
[0003] Generally, the Stober method is used to prepare colloidal silicon dioxide. Under the catalysis of an alkali, while hydrolyzing an alkyl silicate (such as methyl orthosilicate or ethyl orthosilicate), condensation and particle growth are carried out to obtain silicon dioxide particles. The dilute silicon dioxide particles are obtained as a finished product with a suitable concentration and solvent through a concentration and replacement process.
[0004] The patent document with the patent number 2021221055620 discloses a device for preparing colloidal silicon dioxide, which integrates multiple independent process flows, enables the organic combination of the synthesis reaction, concentration reaction, and replacement reaction of colloidal silicon dioxide, realizes the industrial preparation of colloidal silicon dioxide with high efficiency in the same reaction kettle, shortens the process flow, and reduces the process difficulty. Although this device does improve the process efficiency, since the liquid output by the condenser contains a methanol solvent and a rich ammonia solvent, and the methanol purity is not high and cannot be reused, it can only be discharged as waste liquid, which not only increases the raw material cost, but also requires a treatment cost for the waste liquid. Summary of the Invention
[0005] Object of the Invention: In order to overcome the deficiencies existing in the prior art, a device for preparing aqueous silicon dioxide with a solvent recovery function is provided, which does not produce waste liquid, reduces the raw material cost, eliminates the waste liquid treatment process, and saves the process cost.
[0006] Technical solution: To achieve the above object, the present utility model provides a device for preparing aqueous silica with a solvent recovery function, which includes a first reaction kettle, a vacuum generator and a condenser, and also includes a second reaction kettle and a methanol collection tank. The vacuum generator is respectively connected to the first reaction kettle and the second reaction kettle. The inlet end and the liquid outlet end of the condenser are respectively connected to the gas outlet of the first reaction kettle and the liquid inlet of the second reaction kettle. The gas outlet end and the liquid inlet end of the condenser are respectively connected to the methanol collection tank and the liquid outlet of the second reaction kettle. The methanol collection tank is connected to the gas return port of the first reaction kettle. A sulfuric acid feeding port and a second heat medium inlet are provided on the second reaction kettle.
[0007] Further, a first feeding port, a second feeding port and a first discharging port are respectively provided on the first reaction kettle, and the first feeding port and the first discharging port are respectively connected to a silica storage tank.
[0008] Further, a first heat medium inlet is provided on the first reaction kettle.
[0009] Further, a first thermometer and a first liquid level gauge are provided on the first reaction kettle.
[0010] Further, a second thermometer and a second liquid level gauge are provided on the second reaction kettle.
[0011] Further, stirrers are provided in both the first reaction kettle and the second reaction kettle.
[0012] Beneficial effects: Compared with the prior art, the present utility model, through the design of the methanol collection tank and the second reaction kettle and the improvement of the connection structure of the condenser, can convert the ammonia in the ammonia-rich solvent into ammonium sulfate through the second reaction kettle, and the ammonium sulfate can precipitate in the methanol collection tank, enabling the methanol solvent to be recycled in real time. This not only reduces the raw material cost, but also does not produce waste liquid during the preparation process, eliminating the waste liquid treatment process and saving the process cost. Description of the drawings
[0013] Figure 1 It is a schematic structural diagram of the present utility model. Specific embodiments
[0014] The following further clarifies the present utility model in conjunction with the drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present utility model and not to limit the scope of the present utility model. After reading the present utility model, various equivalent modifications made by those skilled in the art to the present utility model all fall within the scope defined by the appended claims of this application.
[0015] Such as Figure 1As shown in the figure, the present utility model provides a device for preparing aqueous silica with a solvent recovery function, which includes a first reaction kettle 1, a second reaction kettle 2, a silica storage tank 3, a vacuum generator 4, a condenser 5, and a methanol collection tank 6. The vacuum generator 4 is respectively connected to the first reaction kettle 1 and the second reaction kettle 2. The inlet end and the outlet end of the condenser 5 are respectively connected to the gas outlet of the first reaction kettle 1 and the liquid inlet of the second reaction kettle 2. The gas outlet end and the liquid inlet end of the condenser 5 are respectively connected to the methanol collection tank 6 and the liquid outlet of the second reaction kettle 2. The methanol collection tank 6 is connected to the gas return port of the first reaction kettle 1. The first reaction kettle 1 is respectively provided with a first feeding port 11, a second feeding port 12, a first discharging port 13, a first heat medium inlet 16, a first thermometer 14, and a first liquid level gauge 15. The first feeding port 11 and the first discharging port 13 are respectively connected to the liquid outlet and the liquid inlet of the silica storage tank 3. The second reaction kettle 2 is provided with a sulfuric acid feeding port 21, a second heat medium inlet 24, a second thermometer 22, and a second liquid level gauge 23. The bottom of the second reaction kettle 2 is provided with a second discharging port 25. Stirrers 7 are arranged in both the first reaction kettle 1 and the second reaction kettle 2.
[0016] In this embodiment, the above device is applied to the preparation process of colloidal silica. The operation process sequentially includes four steps: hydrolysis reaction, concentration, replacement, and solvent recovery. The specific process is as follows:
[0017] (1) Hydrolysis reaction:
[0018] First, a certain amount of ultra-high-purity methanol, ammonia water, and aqueous solution are successively added into the first reaction kettle 1 through the second feeding port 12, and stirred evenly by the stirrer 7. Then, a heat source is introduced through the first heat medium inlet 16 to heat up the materials in the first reaction kettle 1. When the temperature of the materials in the first reaction kettle 1 reaches the required reaction temperature, a mixed solution of ultra-methanol and methyl orthosilicate with a certain quantitative ratio is added through the second feeding port 12 at a certain feeding speed. After the materials in the first reaction kettle 1 undergo hydrolysis and condensation polymerization reactions for a certain period of time, a dilute silica solution is obtained. After the preparation reaction is completed, the input of the heat source is closed, and a cold source is introduced through the cold medium inlet to cool down the materials in the reaction kettle 1. The cold source is discharged through the cold medium outlet. After the temperature reduction is completed, the dilute silica solution in the first reaction kettle 1 is introduced into the silica storage tank 3 as needed.
[0019] (2) Concentration:
[0020] The dilute silica solution obtained after the hydrolysis reaction is evaporated to obtain silica with a higher concentration. A certain amount of the dilute silica solution enters the first reaction kettle 1 through the first feeding port 11, is stirred evenly by the stirrer 7, and then a heat source is introduced through the first heat medium inlet 16 to heat up the materials in the first reaction kettle 1. At the same time, the whole device is evacuated by the vacuum generator 4. When the inside of the first reaction kettle 1 is under negative pressure, the methanol in the dilute silica solution evaporates, and the methanol gas enters the condenser 5 through the pipeline for condensation to achieve the condensation of the methanol gas. Then the condensed liquid enters the second reaction kettle 2; during the methanol vacuum distillation process, by controlling the matching relationship between the feeding speed of the dilute silica solution at the first feeding port 11 and the discharging speed at the methanol vapor exhaust port, the material volume in the first reaction kettle 1 is maintained at a constant liquid level evaporation and concentration under a high liquid level until the required silica concentration requirement is reached; after the concentration is completed, the concentrated product in the first reaction kettle 1 enters the replacement step.
[0021] (3) Replacement:
[0022] The concentrated liquid is subjected to solvent replacement to further remove the remaining methanol in it and perform water replacement. The silica concentrated liquid is further heated in the first reaction kettle 1, and ultrapure water with the same volume or more than the evaporation amount of the silica concentrated liquid is added from the second feeding port 12 to maintain the constant liquid level of the materials in the first reaction kettle 1. When the material temperature and pH value in the first reaction kettle 1 reach 100 °C and 7.4 or lower respectively, the replacement step is completed. After the solvent replacement is completed, the heat source input is closed, and a refrigerant is introduced through the cold medium inlet to cool down the materials in the first reaction kettle 1. The refrigerant is discharged from the cold medium outlet through the jacket. After the cooling is completed, the colloidal silica obtained in the first reaction kettle 1 is transported from the discharge port to the designated storage tank. The obtained colloidal silica has a metal impurity concentration of 100 ppb or lower, and at the same time, the concentration of the colloidal silica is not lower than 20%.
[0023] (4) Methanol recovery and utilization:
[0024] Due to the methanol, water, and ammonia generated during the concentration and replacement processes, methanol is recovered and purified. Dilute sulfuric acid is added to the second reaction kettle 2 through the sulfuric acid feeding port 21, and stirring is started to convert the ammonia in the ammonia-rich solvent into ammonium sulfate. The alkalinity is sampled and tested, and when the pH = 4 - 5, the dilute sulfuric acid is stopped. At the same time, the whole device is evacuated by the vacuum generator 4. When the methanol collection tank 6 is under negative pressure, the methanol solution evaporates into a gas state and enters the condenser 5 for condensation. The condensed liquid enters the methanol collection tank 6, and the ammonium sulfate in the condensed liquid will precipitate in the methanol collection tank 6 to achieve the purification and collection of methanol. The high-purity methanol in the methanol collection tank 6 can flow into the first reaction kettle 1 through the pipeline to continue the hydrolysis reaction, realizing the recovery and utilization of methanol.
[0025] As can be seen from the above process, high-purity extraction and recycling of methanol are achieved in the preparation process, and no waste liquid is generated, which not only reduces the raw material cost, but also eliminates the waste liquid treatment process and saves the process cost.
Claims
1. A water-based silica preparation device with a solvent recovery function, comprising a first reaction kettle, a vacuum generator and a condenser, characterized in that: It also includes a second reactor and a methanol collection tank, the vacuum generator is connected to the first reactor and the second reactor respectively, the air inlet and liquid outlet of the condenser are connected to the air outlet of the first reactor and the liquid inlet of the second reactor respectively, the air outlet and liquid inlet of the condenser are connected to the methanol collection tank and the liquid outlet of the second reactor respectively, the methanol collection tank is connected to the air return port of the first reactor, and the second reactor is provided with a sulfuric acid feeding port and a second heat medium inlet.
2. The aqueous silicon dioxide preparation device with solvent recovery function according to claim 1, characterized in that: The first reaction kettle is provided with a first feeding port, a second feeding port and a first discharging port, respectively. The first feeding port and the first discharging port are connected to the silicon dioxide liquid storage tank respectively.
3. The aqueous silicon dioxide preparation device with solvent recovery function according to claim 1, characterized in that: The first reaction kettle is provided with a first heat medium inlet.
4. The aqueous silicon dioxide preparation device with solvent recovery function according to claim 1, characterized in that: The first reaction kettle is provided with a first thermometer and a first liquid level gauge.
5. The aqueous silicon dioxide preparation device with solvent recovery function according to claim 1, characterized in that: The second reactor is provided with a second thermometer and a second liquid level gauge.
6. The aqueous silicon dioxide preparation device with solvent recovery function according to claim 1, characterized in that: Agitators are provided in the first reactor and the second reactor.