A high-purity potassium sulfate production device and method using membrane concentration and salting-out process

Abstract

The application belongs to the field of alkali metal compounds, and provides a high-purity potassium sulfate production method using membrane concentration and salting-out process, comprising: filtering a solution containing potassium sulfate through low-pressure nanofiltration membrane and high-pressure nanofiltration membrane in sequence, and collecting high-pressure filtration concentrated liquid; adding potassium tartrate and potassium chloride into the high-pressure filtration concentrated liquid, and performing salting-out in a gradient cooling process, and collecting materials after the salting-out reaction; performing gravity sedimentation crystallization on the materials after the salting-out reaction, collecting heavy components, performing solid-liquid separation on part of the heavy components, and obtaining solid materials; washing, solid-liquid separating and drying the solid materials, and then the high-purity potassium sulfate is obtained. The application improves the product purity and efficiency on the basis of retaining the core of the original process through gradient temperature control, dynamic potassium chloride regulation, crystallization post-treatment strengthening and complexation-salting-out synergy, and solves the problems of insufficient yield and purity of potassium sulfate in the traditional process.

Description

Technical Field

[0001] This invention belongs to the field of alkali metal compounds and relates to a high-purity potassium sulfate production apparatus and method using membrane concentration and salting-out processes. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] In the potash and alkali chemical production process, low-concentration potassium chloride brine is generated, whose main components include: potassium chloride 180g / L-220g / L and potassium sulfate 3g / L-10g / L. If the K2SO4 (potassium sulfate) in the system is not treated in time, it will continuously accumulate during the production process of the ion-exchange membrane potash and alkali unit, forming a precipitate on the electrode surface, affecting production energy consumption and the service life of the chloride ion exchange membrane.

[0004] Currently, low-pressure nanofiltration membranes are commonly used to concentrate potassium sulfate solutions to 25 g / L-35 g / L under pressure, followed by the addition of calcium chloride to reduce the K₂SO₄ content in the system. However, the salting-out reaction temperature of this method is within a wide range of 35℃-60℃, making it difficult to simultaneously achieve potassium chloride dissolution and potassium sulfate crystallization, thus the purity and yield of potassium sulfate need to be improved. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a high-purity potassium sulfate production apparatus and method employing membrane concentration and salting-out processes. This invention uses potassium tartrate as a complexing agent in conjunction with ultrasonic treatment, effectively improving salting-out efficiency and significantly enhancing the purity and crystallization efficiency of potassium sulfate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A first aspect of the present invention provides a method for producing high-purity potassium sulfate using membrane concentration and salting-out processes, comprising: The potassium sulfate solution was filtered sequentially through a low-pressure nanofiltration membrane and a high-pressure nanofiltration membrane, and the high-pressure filtration concentrate was collected. Potassium tartrate and potassium chloride are added to the high-pressure filtration concentrate, and salting out is carried out during the gradient cooling process. The material after the salting-out reaction is collected. The material after the salting-out reaction is subjected to gravity sedimentation crystallization to collect the heavy components. A portion of the heavy components is then subjected to solid-liquid separation to obtain the solid material. The solid material is washed, separated into solid and liquid components, and dried to obtain the final product.

[0007] In a second aspect, the present invention provides a high-purity potassium sulfate production apparatus employing membrane concentration and salting-out processes, comprising: a raw brine storage tank, a low-pressure nanofiltration membrane filter, an intermediate tank, a high-pressure nanofiltration membrane filter, an integrated salting-out reactor, a gravity settling crystallization tank, a two-stage washing tank, a drying device, and a silo connected in sequence. The integrated salting-out reactor is equipped with a double-layer differential speed stirrer and an ultrasonic generator.

[0008] Beneficial effects of the present invention (1) In this invention, potassium tartrate is used as a complexing agent in combination with ultrasonic treatment. The potassium sulfate precipitation rate is increased from 70%-80% in the original process to 85%-90%, and the crystal particle size is uniform with D50 (50% passing particle size) of 50μm-80μm.

[0009] (2) This invention does not require the introduction of precipitants such as barium chloride and calcium chloride, thus avoiding the use of toxic substances and scaling problems; it adopts two-stage nanofiltration membrane concentration, reducing the investment in high-pressure pumps and membranes; and it does not require the addition of pure water or cleaning agents during the production process, thus avoiding membrane damage.

[0010] (3) The present invention dynamically regulates potassium chloride, reducing the excess potassium chloride rate from 10%-15% in the original process to ≤3%, and reducing the residual amount of KCl (potassium chloride) in the mother liquor by 20%-30%.

[0011] (4) The present invention uses two-stage washing to reduce the Cl⁻ (chloride ion) content from 0.5% in the original process to ≤0.1%. At the same time, low-temperature drying is used to avoid potassium sulfate decomposition (the traditional high-temperature drying decomposition rate is 1%-2%).

[0012] (5) The production method of the present invention is simple, practical and easy to promote. Attached Figure Description

[0013] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. Exemplary embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0014] Figure 1 This is a schematic diagram of a high-purity potassium sulfate production device using membrane concentration and salting-out process according to the present invention, wherein: 1. raw brine storage tank, 2. low-pressure nanofiltration membrane filter, 3. intermediate tank, 4. high-pressure nanofiltration membrane filter, 5. integrated salting-out reactor, 6. gravity sedimentation crystallization tank, 7. centrifuge, 8. two-stage washing tank, 9. drying equipment, 10. silo; Figure 2The diagram shows the integrated salting-out reactor structure of the present invention, wherein: 5-1. feed inlet, 5-2. filter screen, 5-3. conical structure, 5-4. double-layer differential speed stirrer, 5-5. jacket, 5-6. spiral coil, 5-7. PLC controller, 5-8. Pt100 platinum resistance thermometer, and 5-9. ultrasonic generator. Detailed Implementation

[0015] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods in the art or product instructions. Similarly, unless otherwise specified, the test methods of this invention are performed in accordance with conventional methods in the art or industry-standard methods or practices. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0017] Terminology Explanation: In this invention, "high-purity potassium sulfate" refers to potassium sulfate with a purity of ≥90%.

[0018] This invention provides a method for producing high-purity potassium sulfate using membrane concentration and salting-out processes, comprising: The potassium sulfate solution was filtered through a low-pressure nanofiltration membrane, and the low-pressure filtrate concentrate was collected. The low-pressure filtration concentrate is filtered through a high-pressure nanofiltration membrane, and the high-pressure filtration concentrate is collected. Potassium tartrate and potassium chloride are added to the high-pressure filtration concentrate, and salting out is carried out during the gradient cooling process. The material after the salting-out reaction is collected. The material after the salting-out reaction is subjected to gravity sedimentation crystallization to collect the heavy components (i.e., crude potassium sulfate crystals). A portion of the heavy components is used as seed crystals and recycled for salting-out, while the remaining heavy components are subjected to solid-liquid separation to obtain solid material. The solid material is washed sequentially with saturated potassium sulfate solution, followed by solid-liquid separation, water rinsing, solid-liquid separation, and drying to obtain the final product.

[0019] The filtration effect of low-pressure nanofiltration membranes is affected by conditions such as pressure, temperature, and pH value. Therefore, this invention has studied pressure, water temperature, etc. Preferably, the filtration conditions of the low-pressure nanofiltration membrane are: temperature 35℃-40℃, pressure 15-30 kg, pH value 3-7, and potassium sulfate concentration 25g / L-35g / L to obtain better filtration effect.

[0020] Pressure, influent salt concentration, pH value, etc., can affect the filtration effect of high-pressure nanofiltration membranes. Therefore, this invention has studied the pressure, potassium sulfate concentration, etc. Preferably, the filtration conditions of the high-pressure nanofiltration membrane are: temperature 35℃-40℃, pressure 30-55 kg, pH value 3-7, and potassium sulfate concentration 70g / L-145g / L to obtain better filtration effect.

[0021] This invention has found that the addition of potassium tartrate can effectively increase the precipitation rate of potassium sulfate and control crystal growth. Therefore, this invention has studied the dosage of potassium tartrate. Preferably, the dosage of potassium tartrate is 0.5 g / L-1 g / L, based on the total volume of the high-pressure filtration concentrate, in order to effectively increase the precipitation rate of potassium sulfate and make the crystal particle size more uniform.

[0022] Preferably, the gradient cooling process includes: a first stage: holding at 60℃-65℃ for 30min-40min; a second stage: holding at 40℃-45℃ for 60min-70min; and a third stage: isothermal treatment at 35℃-40℃ to improve crystallization efficiency.

[0023] In traditional methods, the amount of potassium chloride added depends on experience and is prone to being excessive or insufficient. Therefore, this invention studies the amount of potassium chloride added, and preferably, the molar ratio of potassium sulfate to potassium chloride is (1.2-1.5):1. The excess potassium chloride rate is reduced from 10%-15% in the original process to ≤3%, and the residual KCl in the mother liquor is reduced by 20%-30%.

[0024] To improve the precipitation effect of potassium sulfate, this invention improves the salting-out device. Preferably, during the salting-out process, the upper layer disperses while the lower layer undergoes ultrasonic breaking up of agglomerates. The upper agitator and filter screen are integrated and linked to promote uniform dispersion of potassium chloride; the lower agitator promotes the dissolution of potassium chloride while preventing potassium sulfate crystals at the bottom of the reactor from being stirred and floating to the surface.

[0025] The upper agitator (above the filter) operates at 80-120 rpm, while the lower agitator (below the filter) operates at 30-60 rpm. The lower agitator is equipped with a 20kHz-50kHz ultrasonic generator (5-9), whose effective range is strictly limited to the crystallization zone below the filter and will not significantly diffuse to the upper layer. The principle is as follows: Ultrasonic waves are mechanical longitudinal waves. When passing through solid media (such as metal mesh or ceramic membrane), they will be severely attenuated due to "acoustic impedance mismatch" (energy loss can reach more than 80%). At the same time, the multi-layered dense structure of the filter will reflect and absorb most of the ultrasonic energy, reducing the intensity of the sound waves penetrating to the upper layer to less than 10% of the original intensity, which is insufficient to interfere with the potassium chloride dispersion process in the upper layer.

[0026] The feed flow rate affects the gravity sedimentation effect. Therefore, this invention studies the flow rate of gravity sedimentation crystallization. Preferably, the specific conditions for gravity sedimentation crystallization are a feed flow rate of 8 m / h-12 m / h and a supernatant overflow rate of 4 m / h-5 m / h to improve the sedimentation effect of potassium sulfate.

[0027] The crystals obtained after gravity sedimentation and centrifugation will contain residual chloride ions. Therefore, this invention washes the solid product to remove chloride ions. Preferably, the solid product is first stirred in a saturated potassium sulfate solution for 5-10 minutes to separate the solid and liquid, and then rinsed with water for 30-60 seconds. After rinsing with water, the liquid is forcibly separated by a filter plate, centrifuge, or other equipment, so that the final residual water is much less than the initial residual mother liquor water. The two-stage washing reduces the Cl⁻ content from 0.5% in the original process to ≤0.1%.

[0028] The present invention also provides a high-purity potassium sulfate production device using membrane concentration and salting-out process, comprising: a raw brine storage tank 1, a low-pressure nanofiltration membrane filter 2, an intermediate tank 3, a high-pressure nanofiltration membrane filter 4, an integrated salting-out reactor 5, a gravity sedimentation crystallization tank 6, a two-stage washing tank 8, a drying device 9, and a silo 10 connected in sequence. The integrated salting-out reactor 5 is equipped with a double-layer differential speed stirrer and an ultrasonic generator 5-9.

[0029] Preferably, the integrated salting-out reactor 5 includes a vessel body, and a gradient temperature control system is provided on the outside of the vessel body to realize a gradient cooling process.

[0030] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0031] Example 1 like Figure 1As shown, this embodiment provides a high-purity potassium sulfate production device using membrane concentration and salting-out process, including: a raw brine storage tank 1, a low-pressure nanofiltration membrane filter 2, an intermediate tank 3, a high-pressure nanofiltration membrane filter 4, an integrated salting-out reactor 5, a gravity sedimentation crystallization tank 6, a two-stage washing tank 8, a drying device 9, and a silo 10 connected in sequence. like Figure 2 As shown, the integrated salting-out reactor 5 includes: a vessel body, the outer wall of which is equipped with a gradient temperature control system. The gradient temperature control system consists of a jacket 5-5, a spiral coil 5-6, a PLC controller 5-7, and a Pt100 platinum resistance thermometer 5-8 (accuracy ±0.1℃). The jacket 5-5 is located on the outer wall of the vessel body, and the spiral coil 5-6 is located between the vessel body and the jacket. The outer wall of the vessel body is also equipped with a PLC controller 5-7 to achieve automated control. The Pt100 platinum resistance thermometer 5-8 is inserted into the vessel body from the top to measure the temperature.

[0032] The upper part of the vessel body is provided with a filter screen 5-2 that only allows liquid to pass through; the upper part of the filter screen 5-2 is provided with a feed inlet 5-1; the vessel body is also provided with a double-layer differential speed stirrer 5-4, wherein the upper stirrer is located above the filter screen 5-2, the lower stirrer is located below the filter screen 5-2, and an ultrasonic generator 5-9 is provided on the lower stirrer; the bottom of the vessel body is a conical structure 5-3.

[0033] Of the two-stage washing tank 8, the first stage is a saturated potassium sulfate solution washing tank, and the second stage is a water rinsing tank. The saturated potassium sulfate solution washing tank removes impurities by washing with saturated potassium sulfate solution, followed by solid-liquid separation by centrifugation; the water rinsing tank reduces water penetration into the crystal by short-time rinsing, and combined with vacuum filtration ensures that water only stays on the crystal surface, facilitating subsequent drying.

[0034] The drying device 9 is a low-temperature radio frequency dryer. It uses 27.12MHz radio frequency drying (power 500-800W), utilizes molecular polarization to generate internal heat, controls the drying temperature at 50℃-60℃, and shortens the drying time from 2 hours to 30 minutes, thus avoiding crystal surface cracking caused by traditional heating.

[0035] Example 2 The production of high-purity potassium sulfate using the apparatus of Example 1 includes the following specific steps: The first step is low-pressure nanofiltration: The solution containing 10 g / L potassium sulfate in the raw brine storage tank 1 is pumped to the low-pressure nanofiltration membrane filter 2. Under a pressure of 15 kg, the 10 g / L potassium sulfate solution is concentrated to 35 g / L to obtain the low-pressure filtration concentrate, which is then transported to the intermediate tank 3. The second step is high-pressure nanofiltration: the low-pressure filtration concentrate in the intermediate tank 3 is transported to the high-pressure nanofiltration membrane filter 4 by a transfer pump. Under a pressure of 30 kg, the 35 g / L potassium sulfate solution is concentrated to 145 g / L to obtain the high-pressure filtration concentrate. The third step is the salting-out reaction: the high-pressure filtered concentrate enters the integrated salting-out reactor 5 through the feed inlet 5-1, while 1 g / L of potassium tartrate is added; the gradient temperature control program is started: 60℃ for 30 min → 40℃ for 60 min → 35℃ constant temperature, the potassium sulfate concentration and feed flow rate are monitored online, the total amount of potassium sulfate per unit time is calculated, and potassium chloride is added according to the molar ratio of potassium sulfate to potassium chloride of 1.2:1; the double-layer differential speed stirrer is linked, the upper layer disperses and the lower layer is ultrasonically broken up and agglomerated, the ultrasonic frequency is 25 kHz.

[0036] The fourth step is gravity sedimentation crystallization. The material after the salting-out reaction is transported to the gravity sedimentation crystallization tank 6 by a conveying pump. The feed flow rate is 8 m / h and the overflow rate of the supernatant is 4 m / h. The light component (supernatant) flows back to the raw brine storage tank 1 through the overflow pipe, and part of the heavy component flows back to the integrated salting-out reactor 5 as seed crystals, and part is transported to the centrifuge 7. Step 5: Centrifugation and two-stage washing; After gravity settling, the material is separated by centrifuge 7, and the solid product is collected. It is first washed in a primary saturated potassium sulfate solution washing tank (solid-liquid ratio 1:5, stirring for 5 min), then centrifuged to separate and collect the solid product; then it is washed in a secondary water rinsing tank for 30 s, and vacuum filtered to reduce the water content to below 5%; the centrifuged clear liquid is transported back to the integrated salting-out reactor 5 to participate in the reaction; Step 6, Drying: After low-temperature radio frequency drying, the purity of the finished product is 99.5%, and the yield is 85.6%.

[0037] Example 3 The production of high-purity potassium sulfate using the apparatus of Example 1 includes the following specific steps: The first step is low-pressure nanofiltration membrane filtration; the solution containing 3g / L potassium sulfate in the raw brine storage tank 1 is pumped to the low-pressure nanofiltration membrane filter 2, concentrated at 30 kg pressure to 25g / L, and the low-pressure filtration concentrate is transported to the intermediate tank 3. The second step is high-pressure nanofiltration membrane filtration. The low-pressure filtration concentrate in intermediate tank 3 is transported to high-pressure nanofiltration membrane filter 4 by a transfer pump and concentrated at 55 kg pressure to make the potassium sulfate concentration 70 g / L, thus obtaining high-pressure filtration concentrate. The third step is the salting-out reaction. The high-pressure filtered concentrate enters the integrated salting-out reactor 5 through inlet 5-1, while 0.5 g / L potassium tartrate is added. The gradient temperature control program is started: 65℃ for 40 min → 45℃ for 70 min → 40℃ constant temperature. The potassium sulfate concentration and feed flow rate are monitored online, and the total amount of potassium sulfate per unit time is calculated. Potassium chloride is added at a molar ratio of potassium sulfate to potassium chloride of 1.5:1. The double-layer differential speed stirrer is linked, with the upper layer dispersing and the lower layer ultrasonically breaking up agglomerates at a frequency of 25 kHz. The fourth step is gravity sedimentation crystallization. The material after the salting-out reaction is transported to the gravity sedimentation crystallization tank 6 by a conveying pump. The feed flow rate is 8 m / h and the overflow rate of the supernatant is 4 m / h. The light component (supernatant) flows back to the raw brine storage tank 1 through the overflow pipe, and part of the heavy component flows back to the integrated salting-out reactor 5 as seed crystals, and part is transported to the centrifuge 7. Step 5: Centrifugation and two-stage washing; After gravity settling, the material is separated by centrifuge 7, and the solid product is collected. It is first washed in a primary saturated potassium sulfate solution washing tank (solid-liquid ratio 1:5, stirring for 5 min), then centrifuged to separate and collect the solid product; then it is washed in a secondary water rinsing tank for 30 s, and vacuum filtered to reduce the water content to below 5%; the centrifuged clear liquid is transported back to the integrated salting-out reactor 5 to participate in the reaction; Step 6, Drying: After low-temperature radio frequency drying, the purity of the finished product is 99.3% and the yield is 84.5%.

[0038] Comparative Example 1 The difference from Example 2 is that potassium tartrate was not added in the third step.

[0039] Test results show that the purity of the finished product is 97.8% (Cl⁻ residue increased by 1.5%), and the yield is 72.3% (potassium sulfate solubility did not decrease, and the amount of precipitation decreased).

[0040] Comparative Example 2 The difference from Example 2 is that in the third step, potassium citrate is used instead of potassium tartrate.

[0041] Test results show that the purity of the finished product is 98.5% (0.3% potassium citrate residue, introducing new impurities), and the yield is 82.1% (potassium citrate has weak complexing ability, and potassium sulfate solubility is reduced).

[0042] Comparative Example 3 The difference from Example 2 is that in the third step, 1.0 g / L EDTA-K2 (dipotassium ethylenediaminetetraacetate) is used instead of potassium tartrate.

[0043] Test results show that the purity of the finished product is 98.2% (EDTA residue of 0.5%, and its complexation stability with potassium ions is too strong, resulting in trace chelate residue), and the yield is 79.3% (EDTA-K2 reduces the solubility of potassium sulfate, but excessive complexation prevents some potassium ions from participating in potassium sulfate crystallization).

[0044] Comparative Example 4 The difference from Example 2 is that in the third step, the ultrasonic waves were not activated in the dual-layer differential stirrer.

[0045] Test results show that the purity of the finished product is 99.1% (ultrasonic treatment has little effect on purity), and the yield is 80.2% (potassium sulfate crystal agglomerates were not broken, and about 5% of small-diameter crystals were lost with the mother liquor).

[0046] The comparison between Example 2 and Comparative Example 1 shows that the complexation effect of potassium tartrate can effectively improve the purity and yield of potassium sulfate.

[0047] As can be seen from the comparison between Example 2 and Comparative Examples 2 and 3, potassium tartrate can better promote the precipitation of potassium sulfate and avoid the introduction of impurities compared with potassium citrate and EDTA-K2, thereby obtaining higher yield and purity.

[0048] As can be seen from the comparison between Example 2 and Comparative Example 4, ultrasonic treatment can promote the breakup of potassium sulfate crystal agglomerates and improve the yield of potassium sulfate.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing high-purity potassium sulfate using membrane concentration and salting-out processes, characterized in that, include: The potassium sulfate solution was filtered sequentially through a low-pressure nanofiltration membrane and a high-pressure nanofiltration membrane, and the high-pressure filtration concentrate was collected. Potassium tartrate and potassium chloride are added to the high-pressure filtration concentrate, and salting out is carried out during the gradient cooling process. The material after the salting-out reaction is collected. The material after the salting-out reaction is subjected to gravity sedimentation crystallization to collect the heavy components. A portion of the heavy components is then subjected to solid-liquid separation to obtain the solid material. The solid material is washed, separated from the liquid, and dried to obtain high-purity potassium sulfate. The gradient cooling process includes: the first stage: holding at 60℃-65℃ for 30min-40min; the second stage: holding at 40℃-45℃ for 60min-70min; and the third stage: isothermal treatment at 35℃-40℃. The amount of potassium tartrate added is 0.5 g / L-1 g / L, based on the total volume of the high-pressure filtered concentrate; The molar ratio of potassium sulfate to potassium chloride is 1.2-1.5:1; During the salting-out process, the upper layer disperses while the lower layer is broken up and agglomerated by ultrasonic waves.

2. The method for producing high-purity potassium sulfate using membrane concentration and salting-out processes as described in claim 1, characterized in that, The conditions for filtration using the low-pressure nanofiltration membrane are: temperature 35℃-40℃, pH value 3-7, and potassium sulfate concentration 25g / L-35g / L. Alternatively, the high-pressure nanofiltration membrane filtration conditions are: temperature 35℃-40℃, pH value 3-7, and potassium sulfate concentration 70g / L-145g / L.

3. The method for producing high-purity potassium sulfate using membrane concentration and salting-out processes as described in claim 1, characterized in that, The specific conditions for gravity sedimentation crystallization are a feed flow rate of 8 m / h-12 m / h and a supernatant overflow rate of 4 m / h-5 m / h.

4. The method for producing high-purity potassium sulfate using membrane concentration and salting-out processes as described in claim 1, characterized in that, The washing process consists of two washes: the solid material is first washed by stirring in a saturated potassium sulfate solution for 5-10 minutes, and after solid-liquid separation, it is then rinsed with water for 30-60 seconds.

5. A high-purity potassium sulfate production apparatus employing membrane concentration and salting-out processes to implement the method according to any one of claims 1-4, characterized in that, include: The raw brine storage tank, low-pressure nanofiltration membrane filter, intermediate tank, high-pressure nanofiltration membrane filter, integrated salting-out reactor, gravity sedimentation crystallization tank, two-stage washing tank, drying equipment and silo are connected in sequence. The integrated salting-out reactor is equipped with a double-layer differential speed stirrer and an ultrasonic generator.

6. The high-purity potassium sulfate production apparatus using membrane concentration and salting-out process as described in claim 5, characterized in that, The integrated salting-out reactor includes a vessel body, and a gradient temperature control system is installed on the outside of the vessel body.

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