Hot-solution crystallization system of sylvite

Abstract

The present application relates to a potassium salt hot solution crystallization system, comprising a hot solution device (1) for dissolving potassium salt by high-temperature dissolving solution, a thickener (7) communicated with the hot solution device, a crystallization device (2) comprising a first-stage crystallizer (21), a second-stage crystallizer (22), a third-stage crystallizer (23) and a centrifuge (8) communicated in sequence, the first-stage crystallizer being communicated with the thickener. A low-temperature mother liquor tank (31) is communicated with the third-stage crystallizer, the centrifuge and the second-stage crystallizer cooler respectively. A second-stage hot well (32) is communicated with the second-stage crystallizer cooler and the first-stage crystallizer cooler respectively. A first-stage hot well (33) is communicated with the first-stage crystallizer cooler. A mother liquor heat exchanger (34) is communicated with the first-stage hot well and the hot solution device respectively. A cooling water device (4) is communicated with the third-stage crystallizer cooler. A steam device (5) is communicated with the mother liquor heat exchanger and the hot solution device respectively. The present application can improve the heat exchange efficiency of the system, reduce the heat energy loss and reduce the steam consumption.

Description

Technical Field

[0001] This invention relates to the field of potassium chloride production technology, and more particularly to a hot-dissolve crystallization system for producing potassium chloride from potassium salt. Background Technology

[0002] Potassium syrup is a raw material for the production of potassium chloride. Its main components are potassium chloride and sodium chloride. Potassium chloride is usually produced by hot-melt crystallization process. That is, potassium syrup and a dissolving solution (mother liquor for crystallization) are added to a hot-melt tank. Based on the principle that potassium chloride and sodium chloride have different solubilities, all potassium chloride in the potassium syrup dissolves in the liquid phase, while sodium chloride exists in the solid phase. Then, the solution is thickened by a thickener, and the solid phase is removed by centrifugation to obtain a saturated pure potassium mother liquor in the liquid phase. The pure potassium mother liquor is then cooled and crystallized to precipitate potassium chloride.

[0003] The hot melt crystallization process includes two temperature-controlled processes: heating to dissolve potassium chloride and cooling to crystallize and precipitate potassium chloride. In the existing process, steam is used to heat the hot melt tank, which requires a huge amount of heat energy. Cooling water is used to cool the crystallization system, resulting in a huge heat loss, low overall heat exchange efficiency, high energy consumption, and high production costs.

[0004] Existing hot melt tanks suffer from low heat exchange efficiency, high steam loss, and high energy consumption when dissolving potassium syrup. Furthermore, the material tends to settle at the bottom of the tank; if it cannot be dissolved quickly, continuous sedimentation reduces the effective dissolution volume, increases the stirring load, and leads to low dissolution efficiency. If potassium chloride in the potassium syrup cannot be fully dissolved into the liquid phase, the potassium chloride content in the light phase of the thickener will be insufficient, while the potassium chloride content in the heavy phase will be excessive, making it difficult to adjust the production process and resulting in a decrease in both the yield and quality of potassium chloride.

[0005] Meanwhile, adding a large amount of steam to the hot melt tank will generate a large amount of condensate in the tank. The condensate mixed into the slurry will reduce the saturation of potassium chloride during heating and dissolving, which will have an adverse effect on the control of the production process.

[0006] In addition, the high impurity content in the material leads to a high failure rate and low heat exchange efficiency of the heat exchange equipment, and also easily causes pipeline blockage, pump failure to operate normally, and interruption of material circulation.

[0007] The primary objective of this invention is to address the problems of low overall heat exchange efficiency, high steam loss, and high energy consumption in existing potassium salt thermal dissolution crystallization processes.

[0008] The second objective is to address the problems of low heat exchange efficiency, high steam loss, and low dissolution efficiency in existing hot melt tanks.

[0009] The third objective is to address the problem of high impurity content in potassium salt materials, which leads to high failure rates of thermal equipment and pipe blockages. Summary of the Invention

[0010] To address the aforementioned problems, this invention provides a potassium sylvite hot-melt crystallization system, comprising a hot-melt device 1, a thickener 7, a crystallization device 2, a heat exchanger 3, a centrifuge 8, a cooling water device 4, and a steam device 5. The hot-melt device 1 uses a high-temperature solution to dissolve potassium sylvite, generating a saturated potassium chloride solution. The thickener 7 is connected to the hot-melt device 1 and concentrates the saturated potassium chloride solution generated by the hot-melt device 1 to obtain a refined potassium mother liquor. The crystallization device 2 includes a primary crystallizer 21, a secondary crystallizer 22, and a tertiary crystallizer 23 connected in sequence.

[0011] The primary crystallizer 21 is connected to the thickener 7, receiving the refined potassium mother liquor and cooling it to crystallize the potassium chloride in the mother liquor, obtaining a primary crystallization solution. The secondary crystallizer 22 receives the primary crystallization solution and cools it to crystallize the potassium chloride in the primary crystallization solution, obtaining a secondary crystallization solution. The tertiary crystallizer 23 receives the secondary crystallization solution and cools it to crystallize the potassium chloride in the secondary crystallization solution, obtaining a crystal slurry and a crystallization mother liquor. The centrifuge 8 receives the crystal slurry and performs solid-liquid separation to obtain a crystallization mother liquor and wet potassium chloride.

[0012] The heat exchange device 3 includes a low-temperature mother liquor tank 31, a secondary hot well 32, a primary hot well 33, and a mother liquor heat exchanger 34. The low-temperature mother liquor tank 31 is connected to the coolers of the tertiary crystallizer 23, the centrifuge 8, and the secondary crystallizer 22, respectively, and receives the crystallization mother liquor produced by the tertiary crystallizer 23 and the centrifuge 8, providing it as a cooling medium to the secondary crystallizer 22 for heat exchange with the primary crystallization solution in the secondary crystallizer 22. The secondary hot well 32 is connected to the coolers of the secondary crystallizer 22 and the primary crystallizer 21, respectively, and receives the crystallization mother liquor after heat exchange in the secondary crystallizer 22, providing it as a cooling medium to the primary crystallizer 21 for heat exchange with the refined potassium mother liquor in the primary crystallizer 21. The primary hot well 33 is connected to the cooler of the primary crystallizer 21 and the mother liquor heat exchanger 34, receiving the crystallization mother liquor after heat exchange in the primary crystallizer 21 and providing it to the mother liquor heat exchanger 34.

[0013] The mother liquor heat exchanger 34 is connected to the hot dissolving device 1 and is used to heat the crystallization mother liquor provided by the primary hot well 33, and then provide it to the hot dissolving device 1 as a dissolving liquid. The cooling water device 4 is connected to the cooler of the tertiary crystallizer 23 and is used to provide cooling water to the tertiary crystallizer 23 to cool the secondary crystallization mother liquor in the tertiary crystallizer 23. The steam device 5 is used to provide steam for heating to the mother liquor heat exchanger 34 and the hot dissolving device 1.

[0014] This invention achieves the recycling of thermal energy in the hot melt crystallization process by heat exchange in the crystallization system. The temperatures of the primary crystallizer 21, the secondary crystallizer 22, and the tertiary crystallizer 23 are controlled at 80℃, 60℃, and 35℃, respectively. The cooling medium for the tertiary crystallizer 23 is cooling water directly. The cooling water after heat exchange is naturally cooled and then pumped back to the tertiary crystallizer 23.

[0015] The mother liquor discharged from the tertiary crystallizer 23 and centrifuge 8 is used as a cooling medium to sequentially exchange heat with the coolers of the secondary crystallizer 22 and the primary crystallizer 21, cooling the solutions in the secondary crystallizer 22 and the primary crystallizer 21. This replaces the traditional method of using cooling water as the cooling medium in the secondary crystallizer 22 and the primary crystallizer 21, reducing the use of cooling water. The circulating cooling water only cools the solution in the tertiary crystallizer; the temperature of the circulating cooling water after heat exchange is relatively low, resulting in a faster cooling rate and allowing for quick resumption of circulation.

[0016] Furthermore, the mother liquor is heated during the cooling process of the solutions in the primary crystallizer 21 and the secondary crystallizer 22, and then used as a solution for potassium syrup, which can significantly reduce heat energy loss and steam consumption. This invention achieves the recycling of heat energy in the cycle from heating and dissolving to cooling and crystallizing, and then from cooling and crystallizing back to heating and dissolving. Simultaneously, it reduces the use of steam in the hot dissolving device 1, preventing the generation of large amounts of condensate within the device and avoiding adverse effects on production process control. In addition, this invention can solve the problems of low overall heat exchange efficiency, high steam loss, and high energy consumption in existing production systems.

[0017] Preferably, the hot melting device 1 includes a hot melting tank 6, which includes a tank body 61, a stirring mechanism 62, and a heating mechanism 63. The tank body 61 has a steam port 611 and a feed port 612 at its upper part, a liquid inlet 613 at its lower side wall, and an overflow port 614 at its upper side wall. A hot melting chamber 64 is formed inside the tank body 61, and a baffle plate 65 is provided on the inner side wall of the tank body 61. The steam port 611 is connected to a steam device 5. The stirring mechanism 62 includes a motor 621 and a stirring rod 622, with the motor 621 located at the top of the tank body 61.

[0018] The upper end of the stirring rod 622 is fixedly connected to the shaft of the motor 621, and the lower end extends through the tank 61 into the hot melting chamber 64. The stirring rod 622 is provided with stirring blades 623. The heating mechanism 63 includes a steam distribution pipe 631, which is annular and horizontally arranged in the hot melting chamber 64, communicating with the steam port 611. The steam distribution pipe 631 is provided with multiple evenly distributed steam nozzles 632, and the openings of the steam nozzles 632 face the stirring blades 623.

[0019] By setting up a hot melting tank 6 including a tank body 61, a stirring mechanism 62 and a heating mechanism 63, a baffle plate 65 is set on the inner side wall of the tank body 61, and a steam distribution pipe 631 is set in an annular shape. Multiple evenly distributed steam nozzles 632 are set on the steam distribution pipe 631, with the openings of the steam nozzles 632 facing the stirring blades 623, so that the steam jets emitted by the steam nozzles 632 are sprayed onto the stirring blades 623. Through the rotation of the stirring blades 623 and the turbulence effect of the baffle plate 65, the steam and slurry are evenly mixed, improving the heat exchange efficiency of the steam, reducing the amount of steam loss, and improving the dissolution efficiency of potassium salt.

[0020] Preferably, the bottom plate 66 of the tank body 61 has a W-shaped longitudinal section, and a first pad 661 and a second pad 662 are provided on the bottom plate 66. The first pad 661 is conical and is fixedly disposed in the middle of the bottom plate 66, and the second pad 662 is annular and is fixedly disposed on the outer periphery of the bottom plate 66.

[0021] By setting a first pad 661 and a second pad 662 on the bottom plate 66 of the hot melting tank 6, the longitudinal section of the bottom plate 66 is W-shaped. After the material enters the hot melting tank 6, the axial thrust generated by the stirring action of the stirring blades 623 and the W-shaped structure of the bottom plate 66 cause the material at the bottom of the hot melting tank 6 to rise. The solid and liquid move relative to each other, making the solid and liquid mix evenly. This solves the problem of excessive fine sodium chloride salt due to excessive local supersaturation during heating and dissolving. It also plays a role in controlling the particle size of sodium chloride, ensuring the stability of process parameters, and effectively improving the yield and quality of potassium chloride.

[0022] Preferably, the heating mechanism 63 further includes a plurality of auxiliary pipes 633. The auxiliary pipes 633 are straight pipes, horizontally arranged, with one end fixedly connected to the steam distribution pipe 631 and internally connected, and the other end extending toward the middle of the tank 61. A mixing port 634 is provided in the middle of the auxiliary pipe 633, and the plurality of auxiliary pipes 633 are evenly distributed in a ring along the steam distribution pipe 631.

[0023] By providing an auxiliary pipe 633 with a mixing port 634, the slurry can enter the mother liquor pipe to mix with steam and then be discharged from the end opening of the auxiliary pipe 633. This not only promotes the flow of slurry near the mixing port 634, but also, with the auxiliary pipe 633 working in conjunction with the stirring blades, makes the steam-slurry mixture more dispersed, thereby improving the stirring effect to achieve sufficient heat exchange, increasing steam heat exchange efficiency, and reducing the impact of steam on the stirring blades.

[0024] Preferably, an insulation layer is provided on the outside of the tank body 61. Providing an insulation layer on the outside of the tank body 61 reduces heat loss from the hot melting tank 6, reduces steam consumption, ensures a stable and uniform internal temperature within the hot melting tank 6, and facilitates precise temperature control within the hot melting tank 6. This solves the problems of unstable hot melting of potassium rock salt and high energy consumption in existing hot melting processes, achieving the goals of energy saving, emission reduction, cost reduction, and efficiency improvement.

[0025] Preferably, the steam nozzle 632 is a Venturi nozzle. The principle behind using a Venturi nozzle for the steam nozzle 632 is that steam is ejected at high speed from the conical nozzle of the Venturi nozzle, creating a low-pressure area around the nozzle guide. Since the Venturi nozzle works by using regional pressure difference and liquid momentum to attract liquid, the high-speed steam and the attracted slurry enter the mixing and diffusion section at a 1:4 fluid ratio and are ejected out. Within the hot melt tank 6, the steam and slurry are thoroughly mixed, greatly improving the heat exchange efficiency of the steam and thus reducing production costs.

[0026] Preferably, the primary hot well 33 includes a shell 331. The shell 331 has a feed inlet 332 at its top, a waste outlet 333 on its upper side wall, and a discharge outlet 334 on its lower side wall. Inside, there is a partition plate 335 and a filter plate 336. The partition plate 335 is vertically positioned within the shell 331, dividing the interior into a mother liquor chamber 337 and a filter chamber 338 that are connected at the top. The filter plate 336 is horizontally positioned in the middle of the filter chamber 338, between the waste outlet 333 and the discharge outlet 334. The feed inlet 332 is located above the mother liquor chamber 337 and communicates with the primary crystallizer 21. The discharge outlet 334 communicates with the mother liquor heat exchanger 34.

[0027] Because large impurities are largely blocked from entering the crystallizer after the potassium hydroxide mother liquor is removed by the overflow weir 75 of the thickener 7, some small impurities can still pass through the gaps in the serrated edges of the overflow weir 75 of the thickener 7 and enter the crystallizer with the potassium hydroxide mother liquor, which can still have a certain impact on the subsequent system processes and equipment. After heat exchange, the temperature of the crystallization mother liquor entering the primary hot well 33 is relatively high, resulting in a relatively large degree of unsaturation and a lighter degree of salt deposition. Therefore, installing an impurity removal device in the primary hot well 33 can minimize the salt deposition problem and maximize the impurity removal efficiency.

[0028] When the primary hot well 33 continuously feeds, the liquid level in the mother liquor chamber 337 rises above the partition plate 335. The crystallization mother liquor enters the filter chamber 338 and is filtered by the filter plate 336. Impurities in the crystallization mother liquor are removed by the filter plate 336, and the crystallization mother liquor is discharged from the outlet 334 to the mother liquor heat exchanger 34. When discharging impurities, the liquid level in the filter chamber 338 is raised above the impurity discharge port 333. The impurities float on the liquid surface, and the impurity discharge port 333 is opened, allowing the impurities to be discharged with the crystallization mother liquor. During long-term operation of the unit, periodic discharge can be performed to remove impurities in the primary hot well 33 in a short time without affecting the production operation of the unit.

[0029] Preferably, the thickener 7 includes a tank body 71, which is cylindrical and forms a thickening cavity 72 inside. The bottom of the tank body 71 is conical. An overflow trough 73 is provided on the upper part of the inner sidewall of the tank body 71, and an overflow outlet 74 communicating with the overflow trough 73 is provided on the sidewall of the tank body 71. The overflow trough 73 is annular and is arranged around the circumference of the inner sidewall of the tank body 71. It is open at the top, and a serrated overflow weir 75 is provided on the upper part of the sidewall of the overflow trough 73 near the inner side of the tank body 71.

[0030] By setting an overflow trough 73 on the upper part of the inner side wall of the tank 71 of the thickener 7, and setting a serrated overflow weir 75 on the upper part of the side wall of the overflow trough 73 near the inner side of the tank 71, impurities in the potassium mother liquor can be blocked and filtered, preventing impurities from directly entering the crystallization process with the overflow potassium mother liquor, preventing impurities from affecting the operation of subsequent equipment and clogging the pipeline, thereby improving product quality.

[0031] Preferably, the hot melting device 1 includes a primary hot melting tank 6a, a secondary hot melting tank 6b, a tertiary hot melting tank 6c, and a quaternary hot melting tank 6d connected in series. Connecting the quaternary hot melting tank 6d in series to dissolve the potassium chloride in the potassium halite ensures complete dissolution, preventing incomplete dissolution of potassium chloride and ensuring that the potassium chloride content in the light phase of the thickener 7 is within acceptable limits, while the potassium chloride content in the heavy phase of the thickener 7 exceeds the standard. This would make it difficult to adjust the crystallization process, affecting product yield and quality.

[0032] Preferably, the mother liquor heat exchanger 34 is a horizontal shell-and-tube heat exchanger. After heating the crystallization mother liquor provided by the primary hot well 33 using the horizontal shell-and-tube heat exchanger, it is supplied as a high-temperature dissolving liquid to the primary hot dissolving tank 6a. This ensures that the temperature of the crystallization mother liquor entering the primary hot dissolving tank 6a is close to the reaction temperature, reducing the amount of steam required to heat each hot dissolving tank, effectively reducing the amount of steam condensate, facilitating control of the saturation during potassium chloride heating and dissolution, and effectively improving the hot dissolving efficiency. The condensate from the mother liquor heat exchanger 34 can be collected and used as flushing water for pipelines. During winter production, to prevent the freshwater pipelines from freezing, it can also be led to a freshwater storage tank for recycling. Attached Figure Description

[0033] Figure 1 Schematic diagram of the connection structure of the potassium halite hot melt crystallization system;

[0034] Figure 2 Schematic diagram of the connection structure of the hot melt device;

[0035] Figure 3 Schematic diagram of the external structure of the hot melt tank;

[0036] Figure 4 Schematic diagram of the cross-sectional structure of the hot melt tank;

[0037] Figure 5 . Figure 4 Enlarged view of point A in the middle;

[0038] Figure 6 . Figure 4 Schematic diagram of the BB cross section;

[0039] Figure 7 Schematic diagram of the external structure of a primary thermal well;

[0040] Figure 8 Schematic diagram of the cross-sectional structure of a primary thermal well;

[0041] Figure 9 Schematic diagram of the external structure of the thickener;

[0042] Figure 10 . Figure 9 Schematic diagram of the CC section;

[0043] Figure 11 . Figure 10 Enlarged diagram of point D in the middle.

[0044] In the diagram, 1. Hot melting device, 2. Crystallization device, 21. Primary crystallizer, 22. Secondary crystallizer, 23. Tertiary crystallizer, 3. Heat exchange device, 31. Low-temperature mother liquor tank, 32. Secondary hot well, 33. Primary hot well, 331. Shell, 332. Feed inlet, 333. Impurity discharge port, 334. Discharge port, 335. Divider plate, 336. Filter plate, 337. Mother liquor chamber, 338. Filter chamber, 339. Discharge valve, 34. Mother liquor heat exchanger, 4. Cooling water device, 5. Steam device, 6. Hot melting tank, 61. Tank body, 611. Steam port, 612. Feed port, 613. Liquid inlet, 614. Overflow port, 615. Exhaust port, 616. Liquid inlet 617. Valve; 618. Discharge port; 62. Discharge valve; 621. Stirring mechanism; 622. Motor; 623. Stirring rod; 624. Stirring blade; 63. Heating mechanism; 631. Steam distribution pipe; 632. Steam nozzle; 633. Auxiliary pipe; 634. Mixing port; 635. Connecting pipe; 64. Hot melt chamber; 65. Baffle plate; 66. Base plate; 661. First pad; 662. Second pad; 6a. Primary hot melt tank; 6b. Secondary hot melt tank; 6c. Tertiary hot melt tank; 6d. Quaternary hot melt tank; 7. Thickener; 71. Tank body; 72. Thickening chamber; 73. Overflow trough; 74. Overflow outlet; 75. Overflow weir; 76. Discharge port; 8. Centrifuge. Detailed Implementation

[0045] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0046] like Figure 1 and Figure 2As shown, the potassium salt hot melt crystallization system includes a hot melt device 1, a thickener 7, a crystallization device 2, a heat exchange device 3, a cooling water device 4, and a steam device 5. The hot melt device 1 includes four hot melt tanks 6, which are connected in series: a primary hot melt tank 6a, a secondary hot melt tank 6b, a tertiary hot melt tank 6c, and a quaternary hot melt tank 6d. The thickener 7 is connected to the quaternary hot melt tank 6d.

[0047] The crystallization apparatus 2 includes a primary crystallizer 21, a secondary crystallizer 22, a tertiary crystallizer 23 and a centrifuge 8 connected in sequence, wherein the primary crystallizer 21 and the thickener 7 are connected.

[0048] The steam ports of the primary hot melt tank 6a, the secondary hot melt tank 6b, the tertiary hot melt tank 6c, and the quaternary hot melt tank 6d are all connected to the steam device 5, and the steam provided by the steam device 5 heats the slurry in each level of the hot melt tank.

[0049] The inlet of the primary hot melt tank 6a is connected to the mother liquor heat exchanger 34; the inlet of the secondary hot melt tank 6b is connected to the overflow port of the primary hot melt tank 6a; the inlet of the tertiary hot melt tank 6c is connected to the overflow port of the secondary hot melt tank 6b; the inlet of the quaternary hot melt tank 6d is connected to the overflow port of the tertiary hot melt tank 6c; and the overflow port of the quaternary hot melt tank 6d is connected to the thickener 7.

[0050] The hot melting device operates by adding potassium syrup and a high-temperature solution (the mother liquor from crystallization, heated in the mother liquor heat exchanger 34) to the primary hot melting tank 6a. Because potassium chloride and sodium chloride have different solubilities at different temperatures, the solubility of potassium chloride increases with increasing temperature, ensuring that all potassium chloride in the potassium syrup dissolves in the slurry. Conversely, the solubility of sodium chloride decreases with increasing temperature, existing as a solid in the saturated potassium chloride solution. The temperature in each stage of the hot melting tank 6 is gradually increased: 63±2℃ in the primary hot melting tank 6a, 73±2℃ in the secondary hot melting tank 6b, 83±2℃ in the tertiary hot melting tank 6c, and 93±2℃ in the quaternary hot melting tank 6d. After the potassium chloride in the potassium salt is initially dissolved in the primary hot dissolving tank 6a, it is sequentially introduced into the secondary hot dissolving tank 6b, the tertiary hot dissolving tank 6c and the quaternary hot dissolving tank 6d for further dissolution. After complete dissolution in the quaternary hot dissolving tank 6d, a saturated potassium chloride solution is obtained. Then, the saturated potassium chloride solution is pumped to the thickener 7 for thickening.

[0051] The hot dissolution device 1 uses a four-stage hot dissolution tank 6d series in series to gradually increase the temperature for hot dissolution. This can completely dissolve the potassium chloride in the potassium salt and prevent the potassium chloride in the potassium salt from not being fully dissolved, which would result in the potassium chloride content in the light phase of the thickener 7 not meeting the standard, and the potassium chloride content in the heavy phase of the thickener 7 exceeding the standard. This would make it difficult to adjust the crystallization system process and affect the yield and quality of the product.

[0052] The saturated potassium chloride solution is concentrated in the thickener 7. After the lower heavy phase is discharged, it is processed. The supernatant overflows and is discharged to obtain refined potassium mother liquor. The refined potassium mother liquor is pumped to the primary crystallizer 21 for crystallization.

[0053] The primary crystallizer 21 is connected to the thickener 7. The temperature inside the primary crystallizer 21 is maintained at around 80°C. Potassium chloride in the refined potassium mother liquor initially crystallizes in the primary crystallizer 21 to form potassium chloride crystal nuclei. After the solution in the upper layer of the primary crystallizer 21 and the slurry in the lower layer of the primary crystallizer 21 are discharged, they are mixed to obtain the primary crystallization solution. The primary crystallization solution is pumped to the secondary crystallizer 22 for further crystallization.

[0054] The temperature inside the secondary crystallizer 22 is maintained at around 60°C. Potassium chloride in the primary crystallization solution crystallizes further inside the secondary crystallizer 22, and potassium chloride crystal nuclei gradually grow into potassium chloride particles. After the solution in the upper layer of the secondary crystallizer 22 and the slurry in the lower layer of the secondary crystallizer 22 are discharged, they are mixed to obtain a secondary crystallization solution. The secondary crystallization solution is pumped to the tertiary crystallizer 23 for further crystallization.

[0055] The internal temperature of the tertiary crystallizer 23 is maintained at around 35°C. Potassium chloride in the secondary crystallization solution crystallizes further in the tertiary crystallizer 23, and potassium chloride particles continue to grow. After the potassium chloride in the solution has crystallized and grown to meet the requirements, the solution in the upper layer of the tertiary crystallizer 23 is discharged to obtain the crystallization mother liquor. The crystallization mother liquor is pumped to the low-temperature mother liquor tank 31. The slurry in the lower layer of the tertiary crystallizer 23 is discharged to obtain the crystal slurry. The crystal slurry is pumped to the centrifuge 8.

[0056] The primary crystallizer 21, secondary crystallizer 22, and tertiary crystallizer 23 have the same structure. Each crystallizer is equipped with a cooler, which is not connected to the interior of the crystallizer. The cooler has a cooling medium inlet and a cooling medium outlet. The cooling medium enters the cooler through the cooling medium inlet to exchange heat with the solution inside the crystallizer. After heat exchange, the cooling medium is discharged through the cooling medium outlet. The crystallizer uses existing equipment, and its detailed structure will not be described here.

[0057] Crystallization thermometers are installed inside the primary crystallizer 21, the secondary crystallizer 22, and the tertiary crystallizer 23.

[0058] Centrifuge 8 separates the crystal slurry discharged from the three-stage crystallizer 23 into solid and liquid phases. The resulting solid phase is wet potassium chloride, and the liquid phase is the crystallization mother liquor. The crystallization mother liquor is pumped to the low-temperature mother liquor tank 31. After drying, the wet potassium chloride yields the potassium chloride product.

[0059] The heat exchange device 3 includes a low-temperature mother liquor tank 31, a secondary hot well 32, a primary hot well 33, and a mother liquor heat exchanger 34.

[0060] The low-temperature mother liquor tank 31 is connected to the tertiary crystallizer 23, the centrifuge 8, and the cooler of the secondary crystallizer, receiving the crystallization mother liquor discharged from the tertiary crystallizer 23 and the centrifuge 8. The temperature of the crystallization mother liquor in the low-temperature mother liquor tank 31 is approximately 30°C. The mixed crystallization mother liquor in the low-temperature mother liquor tank 31 serves as the cooling medium for the secondary crystallizer, and is pumped to the cooler of the secondary crystallizer to exchange heat and lower the temperature of the primary crystallization solution in the secondary crystallizer.

[0061] The secondary hot well 32 is connected to the coolers of both the secondary crystallizer 22 and the primary crystallizer 21, receiving the mother liquor after heat exchange in the secondary crystallizer 22. The temperature of the mother liquor in the secondary hot well 32 is approximately 55°C. The mother liquor in the secondary hot well 32 serves as the cooling medium for the primary crystallizer, and is pumped to the cooler of the primary crystallizer to exchange heat and lower the temperature of the refined potassium mother liquor in the primary crystallizer.

[0062] The primary hot well 33 is connected to the primary crystallizer 21 and receives the mother liquor after heat exchange in the primary crystallizer 21. The temperature of the mother liquor in the primary hot well 33 is about 75°C. The mother liquor in the primary hot well 33 is used as a solution for potassium salt and is pumped to the mother liquor heat exchanger 34 for heating.

[0063] Setting the temperature of the mother liquor after heat exchange in the secondary crystallizer 22 to approximately 55°C and the temperature of the mother liquor after heat exchange in the primary crystallizer 21 to 75°C ensures efficient heat exchange in the secondary crystallizer 22 and the primary crystallizer 21, allowing them to cool down to the design temperature, while maximizing the recovery of heat from the crystallization device.

[0064] The mother liquor heat exchanger 34 is connected to the primary hot well 33, the primary hot melting tank, and the steam unit 5. Steam supplied by the steam unit 5 heats the crystallizing mother liquor transported from the primary hot well 33, providing it as a high-temperature dissolving liquid to the primary hot melting tank 6a. The mother liquor heat exchanger 34 is a horizontal shell-and-tube heat exchanger. The temperature of the crystallizing mother liquor after heat exchange in the mother liquor heat exchanger 34 is approximately 90°C.

[0065] The mother liquor from the primary hot well 33 is heated by a horizontal shell-and-tube heat exchanger and then supplied as a high-temperature dissolving liquid to the primary hot dissolving tank 6a. This brings the temperature of the mother liquor entering the primary hot dissolving tank 6a close to the designed reaction temperature, which reduces the amount of steam used to heat each stage of the hot dissolving tank. This also effectively reduces the amount of condensate generated by steam in each stage of the hot dissolving tank, facilitates the control of the saturation of potassium chloride during heating and dissolving, and effectively improves the hot dissolving efficiency.

[0066] The condensate from the mother liquor heat exchanger 34 can be collected and used as flushing water for some pipelines. In winter production, to prevent the fresh water pipeline from freezing, it can also be led to the fresh water storage tank for recycling.

[0067] The cooling water device 4 is connected to the cooler of the third-stage crystallizer 23, and provides cooling circulating water to the cooler of the third-stage crystallizer 23 to cool down the secondary crystallization solution in the third-stage crystallizer 23.

[0068] The steam device 5 is connected to the steam ports of the mother liquor heat exchanger 34 and the hot melt tanks at each stage, respectively, to provide steam for heating to the mother liquor heat exchanger 34 and the hot melt tanks at each stage.

[0069] This invention uses the crystallization mother liquor discharged from the tertiary crystallizer 23 and centrifuge 8 as a cooling medium to exchange heat in the secondary crystallizer 22 and primary crystallizer 21 in sequence, thereby cooling the solution in the secondary crystallizer 22 and primary crystallizer 21. This replaces the traditional method of using cooling water as the cooling medium in the secondary crystallizer 22 and primary crystallizer 21, thus reducing the use of cooling water.

[0070] Furthermore, the circulating cooling water is only used as a cooling medium for the tertiary crystallizer to lower its temperature. After heat exchange, the temperature of the circulating cooling water is relatively low, resulting in a faster cooling rate and allowing for rapid and repeated recycling. This invention solves the problems of low overall heat exchange efficiency, high steam loss, and high energy consumption in existing production systems.

[0071] Moreover, the mother liquor is heated during the heat exchange cooling process with the solutions in the primary crystallizer 21 and the secondary crystallizer 22, and then used as a solution for dissolving potassium syrup at high temperatures, which can significantly reduce heat loss and reduce the amount of steam used.

[0072] This invention realizes the recycling of thermal energy in the cycle from heating and dissolving to cooling and crystallizing, and then from cooling and crystallizing back to heating and dissolving. At the same time, it reduces the use of steam in each stage of the hot melt tank and prevents the generation of a large amount of condensate in each stage of the hot melt tank, which would have an adverse effect on the control of the production process.

[0073] like Figure 3 and Figure 4 As shown, the hot melting tank 6 includes a tank body 61, a stirring mechanism 62, and a heating mechanism 63. The upper part of the tank body 61 is provided with a steam port 611, a feeding port 612, and an exhaust port 615. The lower part of the side wall is provided with a liquid inlet 613, and the upper part of the side wall is provided with an overflow port 614. A hot melting chamber 64 is formed inside. A baffle 65 is provided on the inner side wall of the tank body 61, and a discharge port 617 is provided on the bottom plate 66 of the tank body 61.

[0074] An inlet valve 616 is provided on the inlet 613, and a drain valve 618 is provided on the outlet 617.

[0075] The bottom plate 66 of the tank body 61 has a W-shaped longitudinal section. A first pad 661 and a second pad 662 are provided on the bottom plate 66. The first pad 661 is conical and is fixedly set in the middle of the bottom plate 66. The second pad 662 is annular and is fixedly set on the outer periphery of the bottom plate 66.

[0076] A first pad 661 and a second pad 662 are set on the bottom plate 66 of the hot melting tank 6, so that the longitudinal section of the bottom plate 66 is W-shaped. After the potassium salt material enters the hot melting tank 6, the axial thrust generated by the stirring action of the stirring blade 623 and the W-shaped structure of the bottom plate 66 cause the potassium salt material at the bottom of the hot melting tank 6 to rise. The solid and liquid generate relative movement, so that the solid and liquid are mixed evenly, improving the dissolution efficiency, ensuring the stability of process indicators, and effectively improving the yield and quality of potassium chloride.

[0077] A hot melt thermometer is installed inside the hot melt tank 6, and an ultrasonic transmitter is installed on the hot melt thermometer.

[0078] Steam port 611 is used to connect to steam device 5.

[0079] The stirring mechanism 62 includes a motor 621 and a stirring rod 622. The motor 621 is located on the top of the tank 61. The upper end of the stirring rod 622 is fixedly connected to the shaft of the motor 621, and the lower end extends through the tank 61 into the hot melt chamber 64. The stirring rod 622 is provided with stirring blades 623.

[0080] like Figure 4 , Figure 5 and Figure 6 As shown, the heating mechanism 63 includes a steam distribution pipe 631 and multiple auxiliary pipes 633. The steam distribution pipe 631 is annular and horizontally arranged in the hot melting chamber 64, located at the lower part of the hot melting chamber 64. The steam distribution pipe 631 is connected to the steam port 611 through a connecting pipe 635. Multiple evenly distributed steam nozzles 632 are provided on the steam distribution pipe 631, and the openings of the steam nozzles 632 face the stirring blades 623.

[0081] The opening of the steam nozzle 632 faces the stirring blade 623, so that the steam jet from the steam nozzle 632 is directed toward the stirring blade 623. Through the rotation of the stirring blade 623 and the turbulence of the baffle plate 65, the steam and slurry are mixed evenly, thereby improving the heat exchange efficiency of the steam, reducing the amount of steam loss, and improving the dissolution efficiency of potassium salt.

[0082] The auxiliary pipe 633 is a straight pipe, horizontally set, with one end fixedly connected to the steam distribution pipe 631 and internally connected, and the other end extending toward the middle of the tank 61. A mixing port 634 is set in the middle of the auxiliary pipe 633, and multiple auxiliary pipes 633 are evenly distributed in a ring along the steam distribution pipe 631.

[0083] A mixing port 634 is provided on the auxiliary pipe 633, which allows the slurry to enter the mother liquor pipe and mix with the steam, and then discharge it from the end opening of the auxiliary pipe 633. This not only promotes the flow of the slurry near the mixing port 634, but also, with the auxiliary pipe 633 and the stirring blades, makes the mixture of steam and slurry more dispersed, which can improve the stirring effect to achieve full heat exchange, improve the steam heat exchange efficiency, and reduce the impact of steam on the stirring blades.

[0084] An insulation layer is provided on the outside of the tank body 61. The insulation layer on the outside of the tank body 61 can reduce heat loss from the hot melting tank 6, reduce steam consumption, make the inside of the hot melting tank 6 stable and uniform, facilitate precise temperature control inside the hot melting tank 6, solve the problems of unstable hot melting of potassium rock salt and high energy consumption in the existing hot melting process, and achieve the goals of energy saving, emission reduction, cost reduction and efficiency improvement.

[0085] The steam nozzle 632 uses a Venturi nozzle. The principle behind this design is that steam is ejected at high speed from the conical nozzle of the Venturi nozzle, creating a low-pressure area around the nozzle guide. Because the Venturi nozzle works by using regional pressure difference and liquid momentum to attract the liquid, the high-speed steam and the attracted slurry enter the mixing and diffusion section at a 1:4 fluid ratio and are then ejected. Within the hot melt tank 6, the steam and slurry are thoroughly mixed, significantly improving the heat exchange efficiency of the steam and thus reducing production costs.

[0086] like Figure 7 and Figure 8 As shown, the primary hot well 33 includes a shell 331. The top of the shell 331 is provided with a feed inlet 332, the upper part of the side wall is provided with a waste discharge outlet 333, the lower part of the side wall is provided with a discharge outlet 334, and the interior is provided with a partition plate 335 and a filter plate 336. The partition plate 335 is vertically arranged inside the shell 331, dividing the interior of the shell 331 into a mother liquid chamber 337 and a filter chamber 338 that are connected at the top.

[0087] A discharge valve 339 is installed on the discharge port 334.

[0088] The filter plate 336 is horizontally arranged in the middle of the filter chamber 338, between the impurity discharge port 333 and the discharge port 334. The feed port 332 is located above the mother liquor chamber 337 and is connected to the primary crystallizer 21. The discharge port 334 is connected to the mother liquor heat exchanger 34.

[0089] Because large impurities are largely blocked from entering the crystallizer after the thickener 7 overflow weir 75 removes impurities from the potassium hydroxide mother liquor, some small impurities can still pass through the gaps in the serrated edges of the overflow weir 75 on the thickener 7 and enter the crystallizer with the mother liquor, affecting the subsequent processes and equipment. After heat exchange, the mother liquor entering the primary hot well 33 has a relatively high temperature, a relatively high degree of unsaturation, and a relatively low degree of salt deposition. Therefore, installing an impurity removal device in the primary hot well 33 can minimize the salt deposition problem and maximize the impurity removal efficiency.

[0090] When the primary hot well 33 continuously feeds, the liquid level in the mother liquor chamber 337 rises above the partition plate 335. The mother liquor enters the filter chamber 338 and is filtered by the filter plate 336. Impurities in the mother liquor are removed by the filter plate 336, and the mother liquor is discharged from the outlet 334 to the mother liquor heat exchanger 34. When discharging impurities, the liquid level in the filter chamber 338 is raised above the impurity discharge port 333. The impurities float on the liquid surface, and the impurity discharge port 333 is opened, allowing the impurities to be discharged with the mother liquor. During long-term operation of the unit, periodic discharge can be performed to remove impurities in the primary hot well 33 in a short time without affecting the production operation of the unit.

[0091] like Figure 9 and Figure 10 As shown, the thickener 7 includes a tank body 71, which is cylindrical and forms a thickening cavity 72 inside. The bottom of the tank body 71 is conical. An overflow groove 73 is provided on the upper part of the inner side wall of the tank body 71. An overflow outlet 74 communicating with the overflow groove 73 is provided on the side wall of the tank body 71. A discharge port 76 is provided at the bottom of the tank body 71, and a discharge valve is provided on the discharge port 76.

[0092] The overflow trough 73 is annular and is arranged around the circumference of the inner sidewall of the pool body 71, with an opening at the top. A serrated overflow weir 75 is provided on the upper part of the sidewall of the overflow trough 73 near the inner side of the pool body 71. (Refer to...) Figure 11 .

[0093] An overflow trough 73 is provided on the upper part of the inner side wall of the tank body 71 of the thickener 7. A serrated overflow weir 75 is provided on the upper part of the side wall of the overflow trough 73 near the inner side of the tank body 71. This can block and filter impurities in the potassium mother liquor, prevent impurities from directly entering the crystallization process with the overflow potassium mother liquor, prevent impurities from affecting the operation of subsequent equipment and clogging the pipeline, thereby improving product quality.

[0094] The present invention also includes a control device, which is electrically connected to various equipment, valves, pumps and thermometers, and the control system operates automatically.

[0095] This invention achieves the recycling of thermal energy in the hot-melt crystallization process through heat exchange in the crystallization system. The mother liquor discharged from the tertiary crystallizer 23 and centrifuge 8 is used as a cooling medium, sequentially entering the secondary crystallizer 22 and the primary crystallizer 21 for heat exchange, thus cooling the secondary crystallizer 22 and the primary crystallizer 21. This replaces the traditional method of using cooling water as the cooling medium for the secondary crystallizer 22 and the primary crystallizer 21, reducing the use of cooling water. The mother liquor is heated during the cooling process of the primary crystallizer 21 and the secondary crystallizer 22, and then serves as the solution for potassium carbonate, significantly reducing heat loss and steam consumption.

[0096] This invention achieves the recycling of thermal energy in the cycle from heating and dissolving to cooling and crystallizing, and then from cooling and crystallizing back to heating and dissolving. Simultaneously, it reduces the use of steam in the hot melting device 1, preventing the generation of large amounts of condensate in each stage of the hot melting tank, which could adversely affect the control of the production process. Furthermore, this invention solves the problems of low overall heat exchange efficiency, high steam loss, and high energy consumption in existing production systems.

[0097] A first pad 661 and a second pad 662 are installed on the bottom plate 66 of the hot melting tank 6, making the longitudinal section of the bottom plate 66 W-shaped. After the potassium salt material enters the hot melting tank 6, the axial thrust generated by the stirring action of the stirring blades 623 and the W-shaped structure of the bottom plate 66 cause the potassium salt material at the bottom of the hot melting tank 6 to rise, and the solid and liquid generate relative movement, so that the solid and liquid are mixed evenly. This solves the problem of excessive fine sodium chloride due to excessive local supersaturation during heating and dissolving, and plays a role in controlling the particle size of sodium chloride, ensuring the stability of process parameters, and effectively improving the yield and quality of potassium chloride.

[0098] An auxiliary pipe 633 is provided, with a mixing port 634 on it. This allows the slurry to enter the mother liquor pipe and mix with steam, then exit from the end opening of the auxiliary pipe 633. This promotes the flow of the slurry near the mixing port 634, making the steam-slurry mixture more dispersed, improving the stirring effect, achieving sufficient heat exchange, and increasing the steam heat exchange efficiency. A steam nozzle 632, using a Venturi nozzle, ensures thorough mixing of steam and potassium salt material within the hot melt tank 6, significantly improving the steam heat exchange efficiency and thus reducing production costs.

[0099] An overflow trough 73 is provided on the upper part of the tank body 71 of the thickener 7, and a serrated overflow weir 75 is provided on the upper part of the side wall of the overflow trough 73. This can block and filter impurities in the potassium mother liquor, preventing impurities from directly entering the crystallization process with the overflow potassium mother liquor and affecting the operation of subsequent equipment.

[0100] Dissolving potassium syrup in a series of multi-stage hot melt tanks ensures complete dissolution of potassium chloride, preventing incomplete dissolution and ensuring that the potassium chloride content in the light phase of the thickener is within acceptable limits, thus affecting product yield and quality.

[0101] After the mother liquor of crystallization in the first-stage hot well 33 is heated by a horizontal shell-and-tube heat exchanger, it is supplied as a dissolving liquid to the first-stage hot dissolving tank 6a. This makes the temperature of the mother liquor of crystallization entering the first-stage hot dissolving tank 6a close to the reaction temperature, which can reduce the amount of steam used to heat each stage of the hot dissolving tank, effectively reduce the amount of steam condensate, facilitate the control of the saturation of potassium chloride during heating and dissolving, and effectively improve the hot dissolving efficiency.

[0102] It should be noted that the above embodiments are illustrative of the invention and not restrictive of the invention, and that alternative embodiments can be devised by those skilled in the art without departing from the scope of the appended claims.

Claims

1. A potassium halite thermal crystallization system, characterized in that, It includes a hot melting device (1), a thickener (7), a crystallizing device (2), a heat exchange device (3), a centrifuge (8), a cooling water device (4), and a steam device (5). The hot dissolving device (1) uses a high-temperature dissolving liquid to dissolve potassium salt and generate a saturated potassium chloride solution; The thickener (7) is connected to the hot dissolving device (1) to concentrate the saturated potassium chloride solution produced by the hot dissolving device (1) to obtain refined potassium mother liquor; The crystallization apparatus (2) includes a primary crystallizer (21), a secondary crystallizer (22), and a tertiary crystallizer (23) connected in sequence. The primary crystallizer (21) is connected to the thickener (7) to receive the potassium chloride mother liquor, cool it, and crystallize the potassium chloride in the mother liquor to obtain a primary crystallization solution. The secondary crystallizer (22) receives the primary crystallization solution, cools it to crystallize the potassium chloride in the primary crystallization solution, and obtains the secondary crystallization solution. The three-stage crystallizer (23) receives the secondary crystallization solution, cools it, and causes the potassium chloride in the secondary crystallization solution to crystallize, thus obtaining crystal slurry and crystallization mother liquor; The centrifuge (8) receives the crystal slurry, performs solid-liquid separation, and obtains crystallization mother liquor and wet potassium chloride. The heat exchange device (3) includes a low-temperature mother liquor tank (31), a secondary hot well (32), a primary hot well (33), and a mother liquor heat exchanger (34). The low-temperature mother liquor tank (31) is connected to the coolers of the tertiary crystallizer (23), centrifuge (8) and secondary crystallizer (22) respectively, and receives the crystallization mother liquor generated by the tertiary crystallizer (23) and centrifuge (8), and provides it as a cooling medium to the secondary crystallizer (22) for heat exchange with the primary crystallization solution in the secondary crystallizer (22); The secondary hot well (32) is connected to the cooler of the secondary crystallizer (22) and the cooler of the primary crystallizer (21) respectively. It is used to receive the crystallization mother liquor after heat exchange in the secondary crystallizer (22) and provide it as a cooling medium to the primary crystallizer (21) for heat exchange with the refined potassium mother liquor in the primary crystallizer (21). The primary hot well (33) is connected to the cooler and mother liquor heat exchanger (34) of the primary crystallizer (21), and receives the crystallized mother liquor after heat exchange in the primary crystallizer (21) and provides it to the mother liquor heat exchanger (34). The mother liquor heat exchanger (34) is connected to the hot dissolving device (1) and is used to heat the crystallization mother liquor provided by the primary hot well (33) and provide it to the hot dissolving device (1) as a dissolving liquid; The cooling water device (4) is connected to the cooler of the three-stage crystallizer (23) and is used to provide cooling water to the three-stage crystallizer (23) to cool the secondary crystallization mother liquor in the three-stage crystallizer (23); The steam device (5) is used to provide steam for heating to the mother liquor heat exchanger (34) and the hot melting device (1).

2. The potassium halite thermal crystallization system according to claim 1, characterized in that, The hot melting device (1) includes a hot melting tank (6), The hot melt tank (6) includes a tank body (61), a stirring mechanism (62), and a heating mechanism (63). The tank (61) is provided with a steam port (611) and a feeding port (612) at the top, a liquid inlet (613) at the bottom of the side wall, an overflow port (614) at the top of the side wall, a hot melting chamber (64) is formed inside, and a baffle plate (65) is provided on the inner side wall of the tank (61). The steam port (611) is connected to the steam device (5); The stirring mechanism (62) includes a motor (621) and a stirring rod (622), wherein the motor (621) is located on the top of the tank (61); The upper end of the stirring rod (622) is fixedly connected to the shaft of the motor (621), and the lower end extends through the tank (61) into the hot melt chamber (64). The stirring rod (622) is provided with stirring blades (623). The heating mechanism (63) includes a steam distribution pipe (631). The steam distribution pipe (631) is annular and horizontally arranged in the hot melt chamber (64), and is connected to the steam port (611). Multiple uniformly distributed steam nozzles (632) are provided on the steam distribution pipe (631). The opening of the steam nozzle (632) faces the stirring blade (623).

3. The potassium halite thermal crystallization system according to claim 2, characterized in that, The bottom plate (66) of the tank body (61) has a W-shaped longitudinal section, and a first pad (661) and a second pad (662) are provided on the bottom plate (66). The first pad (661) is conical and is fixedly installed in the middle of the base plate (66); The second pad (662) is annular and is fixedly disposed on the outer periphery of the base plate (66).

4. The potassium halite thermal crystallization system according to claim 3, characterized in that, The heating mechanism (63) also includes multiple auxiliary tubes (633), The auxiliary pipe (633) is a straight pipe, horizontally set, with one end fixedly connected to the steam distribution pipe (631) and internally connected, and the other end extending toward the middle of the tank (61). A mixing port (634) is provided in the middle of the auxiliary pipe (633). The auxiliary pipes (633) are evenly distributed in a ring along the steam distribution pipe (631).

5. The potassium halite thermal crystallization system according to claim 4, characterized in that, The tank body (61) is provided with an insulation layer on the outside.

6. The potassium halite thermal crystallization system according to claim 5, characterized in that, The steam nozzle (632) is a Venturi nozzle.

7. The potassium halite thermal crystallization system according to claim 6, characterized in that, The primary thermal well (33) includes a shell (331), The shell (331) is provided with a feed inlet (332) at the top, a waste discharge outlet (333) at the upper part of the side wall, a discharge outlet (334) at the lower part of the side wall, and a partition plate (335) and a filter plate (336) inside. The partition plate (335) is vertically arranged inside the shell (331), dividing the interior of the shell (331) into a mother liquor chamber (337) and a filter chamber (338) that are connected at the top; The filter plate (336) is horizontally arranged in the middle of the filter chamber (338), between the impurity discharge port (333) and the discharge port (334); The feed inlet (332) is located above the mother liquor chamber (337) and is connected to the primary crystallizer (21); The discharge port (334) is connected to the mother liquor heat exchanger (34).

8. The potassium halite thermal crystallization system according to claim 7, characterized in that, The thickener (7) includes a tank (71), The pool body (71) is cylindrical and forms a dense cavity (72) inside. The bottom of the pool body (71) is conical. An overflow trough (73) is provided on the upper part of the inner side wall of the pool body (71). An overflow outlet (74) communicating with the overflow trough (73) is provided on the side wall of the pool body (71). The overflow trough (73) is circular and is arranged around the circumference of the inner sidewall of the pool body (71). It is open at the top and a sawtooth-shaped overflow weir (75) is provided on the upper part of the sidewall of the overflow trough (73) near the inner side of the pool body (71).

9. The potassium halite thermal crystallization system according to claim 8, characterized in that, The hot melting device (1) includes a primary hot melting tank (6a), a secondary hot melting tank (6b), a tertiary hot melting tank (6c), and a quaternary hot melting tank (6d) connected in series.

10. The potassium halite thermal crystallization system according to any one of claims 1 to 9, characterized in that, The mother liquor heat exchanger (34) is a horizontal shell-and-tube heat exchanger.

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