A salt field by-product recycling calcium-magnesium-sulfur composite system and a preparation method and application thereof

Abstract

The present application relates to resource recycling technical field, especially relate to a kind of salt field by-product recycling calcium magnesium sulfur composite system, including pretreatment module, for crushing salt gypsum, and proportionally transport with the stored bitter brine of crushed salt gypsum;Reaction aging module is set in the rear end of pretreatment module, including the dechlorination reactor and controllable aging bin connected in turn, dechlorination reactor is transported to bitter brine of pretreatment module and carries out alkali reaction;Controllable aging bin is used to carry out aging to slurry after reaction;Separation washing module is set in the rear end of reaction aging module, for washing filtration to slurry after aging by controllable aging bin;Post-processing module, for drying and crushing to filter cake after washing filtration by separation washing module.The salt field by-product recycling calcium magnesium sulfur composite system provided by the present application combines mechanical turning and air disturbance, ensures the stability of product phase structure during aging process, greatly improves product quality.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and in particular to a calcium-magnesium-sulfur composite system for the reuse of salt field by-products, its preparation method, and its application. Background Technology

[0002] Seawater salt production generates a large amount of byproducts annually, such as bittern and gypsum. Bittern is rich in magnesium, potassium, sulfur, and chloride ions, while gypsum's main component is calcium sulfate. Currently, most of these byproducts are not effectively utilized; their storage or discharge not only occupies land but also easily causes environmental pollution due to their high chloride content.

[0003] In agricultural production, calcium, magnesium, and sulfur are essential medium-level elements for crops. Long-term application of chemical fertilizers has led to an imbalance of these elements in the soil, necessitating replenishment. Current technologies primarily employ chemical methods to treat bittern, but this process is lengthy, and because the equipment used is conventional and lacks specific treatment tailored to the properties of bittern, problems arise such as incomplete dechlorination, high chlorine content in the product, and unstable physical properties. Furthermore, there is a lack of a dedicated equipment system for the overall processing of salt field by-products, enabling continuous, stable, and efficient production from raw materials to finished products. This results in high production costs and inconsistent product quality, severely limiting the high-value utilization of salt industry by-products.

[0004] Therefore, developing an integrated and dedicated production system to realize the resource utilization, productization, and high-value-added processing of salt industry by-products has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a calcium-magnesium-sulfur composite system for the recycling of salt field by-products, its preparation method and application, so as to solve the problems of incomplete treatment and low quality of existing salt industry by-product recycling systems.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a calcium-magnesium-sulfur composite system for the recycling of salt field by-products, comprising: The pretreatment module is used to crush salt gypsum and proportionally transport the crushed salt gypsum to the stored bittern. The reaction aging module, located at the rear end of the pretreatment module, includes a dechlorination reactor and a controllable aging chamber connected in series. The dechlorination reactor performs an alkali reaction on the bittern supplied from the pretreatment module. The controllable aging chamber includes an aging body, a material distribution component, a temperature and humidity control component, and a detection component. The aging body has an aging cavity inside. The material distribution component is distributed along the length of the aging cavity and is located in the middle of the aging cavity. The temperature and humidity control component is located at the bottom of the aging cavity. The detection components are distributed at intervals within the aging cavity. The temperature and humidity control component is used to supply steam and hot air into the aging cavity from bottom to top. The detection components are used to detect the temperature and humidity in various areas within the aging cavity. The detection components are electrically connected to the material distribution component and the temperature and humidity control component. The separation and washing module is located at the rear end of the reaction aging module and is used to wash and filter the slurry that has been aged in the controllable aging chamber. The post-processing module is used to dry and pulverize the filter cake after it has been washed and filtered by the separation and washing module.

[0007] In one embodiment, the material distribution assembly includes a drive motor, a drive rod, a fixed frame, and a swing plate; one end of the drive rod is connected to the drive motor, and the other end of the drive rod is rotatably connected to the inner wall of the aging body; multiple fixed frames are arranged at intervals around the drive rod, and the fixed frames extend from the drive rod in a direction away from the drive rod, and the swing plate is embedded in the fixed frame.

[0008] In one embodiment, the swing plate is rotatably connected to the side of the fixed frame away from the drive rod via a swing shaft. The fixed frame is provided with a blocking inclined wall, which is disposed on both sides of the swing shaft. The blocking inclined wall is used to limit the rotation angle of the swing plate.

[0009] In one embodiment, each fixed frame is provided with multiple swing plates.

[0010] In one embodiment, the temperature and humidity control component includes a partition plate, a steam pipe, a hot air pipe, and a mixing pipe. The partition plate is disposed at the bottom of the aging chamber, the steam pipe and the hot air pipe are disposed below the partition plate, and a mixing pipe is disposed between the partition plate and the steam pipe. The partition plate is provided with a spray nozzle corresponding to the mixing pipe, and the mixing pipe is connected to the spray nozzle.

[0011] In one embodiment, the mixing pipe has two sets of mixing channels, the initial ends of which are connected to a steam pipe and a hot air pipe, respectively. The two sets of mixing channels converge and separate alternately at least twice in the mixing pipe before being connected to the injection port.

[0012] In one embodiment, the temperature and humidity control component further includes a guide turbine fan and a distribution cavity. The guide turbine fan is arranged in an array above the spacer plate, and the injection port is arranged around the rotation axis of the guide turbine fan. The distribution cavity is arranged below the spacer plate corresponding to the guide turbine fan. The injection port is connected to the distribution cavity, and the distribution cavity is connected to the mixing pipe.

[0013] In one embodiment, the steam pipe and the hot air pipe are respectively connected to the mixing pipe through a control pipe, and the control pipe is equipped with a solenoid valve, which is electrically connected to the detection component.

[0014] In one embodiment, the pretreatment module includes a first crusher and a bittern storage tank for storing and conveying bittern.

[0015] In one embodiment, the separation and washing module includes a multi-stage countercurrent washing filter press. Further, the multi-stage countercurrent washing filter press is a chamber filter press or a plate and frame filter press.

[0016] In one embodiment, the post-processing module includes a dryer and a second pulverizer connected in series.

[0017] This invention also provides a preparation method using any of the above-described salt field by-product recycling calcium-magnesium-sulfur composite systems, the steps of which are as follows: S1. Place the salt gypsum into the pretreatment module for crushing. Crush the salt gypsum to 80-200 mesh using a salt gypsum crusher. Then, feed the crushed salt gypsum and bittern into the dechlorination reactor at a mass ratio of 1:(0.5-3). S2, salt gypsum and bittern are mixed in a dechlorination reactor. After mixing, an alkaline compound is added, and the mixture is reacted for 1 to 3 hours under continuous stirring, pH 9.0 to 11.0 and temperature 40℃ to 80℃. S3. The post-reaction slurry obtained in S2 is transported to a controlled aging chamber and aged for 3 to 7 days at a temperature of 25℃ to 60℃ and a humidity of 60% to 85%. S4. Pump the aged slurry into the separation and washing module for solid-liquid separation and multi-stage countercurrent washing to obtain filter cake; S5. The filter cake obtained in S4 is conveyed to the post-processing module and dried at 80℃~120℃ until the moisture content is less than 10%, and then pulverized to 60~100 mesh to obtain the calcium magnesium sulfur composite product.

[0018] Preferably, the alkaline compound includes any one or a combination of calcium oxide, calcium hydroxide, or magnesium oxide.

[0019] Preferably, the calcium-magnesium-sulfur composite product has a pH value of 8.5 to 10.5, a chloride ion content of ≤3%, and contains citrate-soluble calcium oxide, citrate-soluble magnesium oxide, and sulfur.

[0020] The present invention also provides an application of the calcium-magnesium-sulfur composite product prepared by the preparation method described above in soil improvement.

[0021] The beneficial effects of this invention are as follows: 1. The calcium-magnesium-sulfur composite system for the recycling of salt field by-products provided by this invention organically integrates key processes such as dechlorination, aging, and washing through specialized equipment, realizing semi-continuous / continuous production from feeding to discharging, and effectively solving the problems of dispersed equipment and low efficiency in traditional processes.

[0022] 2. The calcium-magnesium-sulfur composite system for the recycling of salt field by-products provided by this invention uses a controllable aging chamber. The aging chamber is equipped with a material distribution component and a temperature and humidity control component. It combines mechanical turning with airflow disturbance to ensure the stability and uniformity of the product phase structure during the aging process, which greatly improves the product quality.

[0023] 3. The method for preparing calcium-magnesium-sulfur composite products for the reuse of salt field by-products provided by this invention efficiently transforms waste salt industry by-products into high-value-added agricultural inputs, realizing "turning waste into treasure," and has both economic and environmental benefits. The treatment process is stable and reliable and has good application value.

[0024] 4. The application of the calcium-magnesium-sulfur composite product provided by this invention in soil improvement: When applied to acidic red soil, the calcium-magnesium-sulfur composite product can effectively regulate soil pH and increase crop yield. It is economical and environmentally friendly, with excellent results and good prospects for promotion.

[0025] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects of the invention and other beneficial effects may be realized and obtained by means of the structures and / or components pointed out in the description and claims. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention; Figure 2 This is a three-dimensional schematic diagram of a controllable aging chamber according to an embodiment of the present invention; Figure 3 for Figure 2 Top view; Figure 4 for Figure 3 Cross-sectional view at point AA in the middle; Figure 5 for Figure 4 A magnified view of a portion of point C in the middle; Figure 6 for Figure 2 The main view; Figure 7 for Figure 6 Cross-sectional view of BB.

[0027] Label Explanation: 1. Pretreatment module; 11. First crusher; 12. Bittern storage tank; 2. Reaction aging module; 21. Dechlorination reactor; 22. Controllable aging chamber; 221. Aging body; 2211. Aging cavity; 222. Material distribution assembly; 2221. Drive motor; 2222. Drive rod; 2223. Fixed frame; 2224. Swing plate; 2225. Swing shaft; 2226. Barrier inclined wall; 223. Temperature and humidity control assembly; 2231. Partition plate; 2232. Steam pipe; 2233. Hot air pipe; 2234. Mixing pipe; 22341. Mixing channel; 2235. Guide turbine fan; 2236. Distribution cavity; 2237. Injection port; 2238. Control pipe; 2239. Solenoid valve; 3. Separation and washing module; 4. Post-treatment module; 41. Dryer; 42. Second crusher. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0030] like Figures 1 to 7 As shown, a calcium-magnesium-sulfur composite system for the recycling of salt field by-products includes: Pretreatment module 1 is used to crush salt gypsum and transport the crushed salt gypsum and stored bittern in a proportional manner. The reaction aging module 2, located at the rear end of the pretreatment module 1, includes a dechlorination reactor 21 and a controllable aging chamber 22 connected in series. The dechlorination reactor 21 performs an alkali reaction on the bittern supplied from the pretreatment module 1. The controllable aging chamber 22 includes an aging body 221, a material distribution component 222, a temperature and humidity control component 223, and a detection component (not shown in the figure). The aging body 221 has an aging cavity 2211 inside. The material distribution component 222 is distributed along the length of the aging cavity 2211 and is located in the middle of the aging cavity 2211. The temperature and humidity control component 223 is located at the bottom of the aging cavity 2211. The detection components are distributed at intervals inside the aging cavity 2211. The temperature and humidity control component 223 is used to supply steam and hot air into the aging cavity 2211 from bottom to top. The detection components are used to detect the temperature and humidity of each area inside the aging cavity 2211. The detection components are electrically connected to the material distribution component 222 and the temperature and humidity control component 223. The separation and washing module 3 is located at the rear end of the reaction aging module 2 and is used to wash and filter the slurry that has been aged in the controllable aging chamber 22. Post-processing module 4 is used to dry and pulverize the filter cake after washing and filtration by separation and washing module 3. Specifically, since the reaction slurry is a solid-liquid two-phase system, the density of gypsum crystals and unreacted particles is greater than that of the liquid phase. If the slurry is left to stand for several hours in the aging chamber 2211, it will rapidly settle, forming a dense precipitate layer and a layered structure of clear liquid on top. This interrupts the solid-liquid contact, causing the residual dechlorination reaction and the ion exchange and rearrangement process of calcium, magnesium, and sulfur components to stagnate, thus failing to achieve the desired aging effect. Therefore, this invention uses the material distribution component 222 and the temperature and humidity control component 223 to agitate and stir the slurry in the aging body 221. This not only breaks the settling trend and maintains the slurry in a moderately suspended state to ensure uniform mass and heat transfer, but also ultimately obtains a high-quality calcium, magnesium, and sulfur composite product with uniform composition, low chlorine residue, and complete crystal structure.

[0031] Specifically, the detection components can use humidity sensors and temperature sensors, which are attached to the inner walls of different areas of the aging body 221 to monitor different areas.

[0032] During the slurry aging process, conventional stirring structures such as paddle and anchor mixers are typically used to achieve full-bottle mixing. These are usually applied in environments with rotation speeds ≥10 rpm, where the resulting strong shear flow field disrupts the slow growth interface of gypsum crystals, leading to excessive grain refinement and increased structural defects. Furthermore, their structure results in both bottom settling and edge dead zones, making it difficult to suppress bottom settling and causing the bottom to remain prone to caking. Therefore, in this embodiment, the material distribution assembly 222 includes a drive motor 2221, a drive rod 2222, a fixed frame 2223, and a swing plate 2224. One end of the drive rod 2222 is connected to the drive motor 2221, and the other end is rotatably connected to the inner wall of the aging body 221. Multiple fixed frames 2223 are spaced around the drive rod 2222, extending from the drive rod 2222 away from it. The swing plate 2224 is embedded within the fixed frame 2223. This configuration uses a drive rod 2222 to drive a fixed frame 2223 that radiates outwards, and a swing plate 2224 that can rotate relative to the fixed frame 2223 is embedded in the fixed frame 2223. When rotating at a very low speed, the swing plate 2224 can form a full-coverage sweep along the axial direction of the aging chamber 2211. By periodically pushing the slurry movement as a whole, the slurry settling trend is broken, and bottom caking is prevented.

[0033] If the movable end of the swing plate 2224 is located on the side away from the drive rod 2222, after the swing plate 2224 is rotated under force, the bottom slurry is subjected more force by the inner wall of the aging body 221, making it difficult to flow upwards sufficiently, resulting in the slurry depositing and hardening on the walls on both sides of the bottom. Therefore, in this embodiment, the swing plate 2224 is rotatably connected to the side of the fixed frame 2223 away from the drive rod 2222 via the swing shaft 2225. The fixed frame 2223 is provided with a blocking inclined wall 2226, which is located on both sides of the swing shaft 2225. The blocking inclined wall 2226 is used to limit the rotation angle of the swing plate 2224. With this configuration, during the operation of the material distribution component 222, the swing plate 2224 is rotatably connected to the far side of the fixed frame 2223. When the swing plate 2224 rotates to the lower position, if it encounters excessive resistance, it can adaptively swing backward to avoid it, thereby forming an upward inclined channel between the fixed frame 2223 and the swing plate 2224. This allows the slurry to pass through the inclined channel and be guided upward, forming a gentle upward flow trend. This avoids the damage to the newly formed gypsum crystals caused by intense rigid shearing, thus providing a stable aging environment for the orderly growth of crystals and the uniform distribution of components. This achieves a dynamic balance between "anti-caking" and "growth preservation," effectively improving the quality of the final product.

[0034] In this embodiment, each fixed frame 2223 is provided with multiple swing plates 2224. This arrangement allows the swing plates 2224 to form inclined channels of different angles and sizes according to the conditions of different areas when facing slurry with uneven density distribution, thereby mixing slurries of different densities, improving the overall uniformity of the slurry, and thus maintaining the stability of the final product quality.

[0035] Since the aging body 221 stores a large amount of slurry and requires the overall temperature of the slurry to remain stable, if conventional heating structures such as heating jackets are used on the outside of the aging body 221, the temperature conduction of the heat exchange structure will be very slow when the temperature fluctuates, making it difficult to meet the heat exchange requirements. Therefore, in this embodiment, the temperature and humidity control component 223 includes a partition plate 2231, a steam pipe 2232, a hot air pipe 2233, and a mixing pipe 2234. The partition plate 2231 is located at the bottom of the aging chamber 2211, the steam pipe 2232 and the hot air pipe 2233 are located below the partition plate 2231, and the mixing pipe 2234 is provided between the partition plate 2231 and the steam pipe 2232. The partition plate 2231 is provided with a spray nozzle 2237 corresponding to the mixing pipe 2234, and the mixing pipe 2234 is connected to the spray nozzle 2237. This design allows hot air and steam to be mixed through the mixing pipe 2234 to form a high-temperature, humid airflow that can be directly injected into the aging chamber 2211. This directly heats and humidifies the slurry, enabling rapid adjustment of aging conditions and ensuring optimal aging results. Furthermore, the injection of the high-temperature, humid airflow causes the slurry at the bottom of the aging chamber 2211 to flow upwards, further preventing the slurry from hardening and settling at the bottom.

[0036] In this embodiment, the mixing pipe 2234 has two sets of mixing channels 22341. The initial ends of the two sets of mixing channels 22341 are connected to the steam pipe 2232 and the hot air pipe 2233, respectively. The two sets of mixing channels 22341 converge and separate alternately at least twice within the mixing pipe 2234 before connecting to the injection port 2237. This arrangement allows the air from the steam pipe 2232 and the hot air pipe 2233 to undergo multiple convergence-separation cycles within the mixing pipe 2234, thereby forming a uniform high-temperature humid airflow, reducing energy consumption while ensuring mixing effect.

[0037] Directly injecting high-temperature, humid airflow can easily cause excessive disturbance to the slurry at the injection port 2237, and can also lead to the high-temperature, humid airflow being directly guided above the aging chamber 2211, resulting in uneven humidity and temperature distribution. Therefore, in this embodiment, the temperature and humidity control component 223 further includes a guide turbine fan 2235 and a distribution chamber 2236. The guide turbine fan 2235 is arranged in an array above the spacer plate 2231, the injection port 2237 is arranged around the rotation axis of the guide turbine fan 2235, and the distribution chamber 2236 is arranged below the spacer plate 2231 corresponding to the guide turbine fan 2235. The injection port 2237 is connected to the distribution chamber 2236, and the distribution chamber 2236 is connected to the mixing pipe 2234. This configuration utilizes the high-temperature, humid airflow to drive the guide turbine fan 2235 to rotate. During rotation, the guide turbine fan 2235 diffuses and distributes the high-temperature, humid airflow, uniformly distributing it into the slurry at the bottom of the aging chamber 2211. This effectively improves the uniformity of humidity and temperature distribution, ensuring stable final product quality. Specifically, each distribution chamber is simultaneously connected to the injection port 2237 surrounding the corresponding guide turbine fan 2235.

[0038] Preferably, each mixing tube 2234 is simultaneously connected to multiple distribution cavities 2236, thereby simultaneously driving the guide turbine fans 2235 in the same row.

[0039] Because the slurry may exhibit uneven temperature and humidity in different areas, it would be difficult to quickly adjust for localized unevenness if all high-temperature humid airflows used the same parameters. Therefore, in this embodiment, the steam pipe 2232 and the hot air pipe 2233 are connected to the mixing pipe 2234 via control pipe 2238. A solenoid valve 2239 is installed within the control pipe 2238 and is electrically connected to the detection component. By installing solenoid valves 2239 in different control pipes 2238, the humidity and temperature of the high-temperature humid airflow ejected from different locations can be changed by adjusting the opening of the solenoid valves 2239, thereby effectively improving adjustability and adaptability. This allows for dynamic adjustments based on the detection results of different areas.

[0040] Preferably, heating elements are wound around the mixing tube 2234 and the control tube 2238. This arrangement allows the mixing tube 2234 and the control tube 2238 to be heated when needed, which not only controls the temperature of the high-temperature humid airflow in different areas, but also prevents steam from condensing inside the mixing tube 2234, ensuring the humidification effect.

[0041] Preferably, the dechlorination reactor 21 is equipped with a dechlorination stirring assembly, a heating and temperature control assembly, an online pH meter, and an automatic dosing assembly electrically connected to the online pH meter. Specifically, the reaction body of the dechlorination reactor 21 can be a cylindrical or kettle-type structure with an internal reaction cavity. The dechlorination stirring assembly extends from the top into the reaction cavity to stir and mix the slurry within. The heating and temperature control assembly adopts a jacketed or coiled heating structure and is located on the outside of the reaction body. The online pH meter extends from the outside of the reaction body into the reaction cavity to detect the pH in different areas within the cavity. The top of the reaction body has a feed inlet, and the bottom has a discharge outlet. The automatic dosing assembly is connected to various locations on the reaction body via dosing pipes, allowing alkaline compounds to enter different areas based on feedback from the online pH meter.

[0042] In this embodiment, the pretreatment module 1 includes a first crusher 11 and a bittern storage tank 12 for storing and transporting bittern.

[0043] In this embodiment, the separation and washing module 3 includes a multi-stage countercurrent washing filter press. Further, the multi-stage countercurrent washing filter press is a chamber filter press or a plate and frame filter press.

[0044] In this embodiment, the post-processing module 4 includes a dryer 41 and a second pulverizer 42 connected in series.

[0045] This invention also provides a preparation method using any of the above-described salt field by-product recycling calcium-magnesium-sulfur composite systems, the steps of which are as follows: S1. Place the salt gypsum into the pretreatment module 1 for crushing. Crush the salt gypsum into 80-200 mesh using a salt gypsum crusher. Then, feed the crushed salt gypsum and bittern into the dechlorination reactor 21 at a mass ratio of 1:(0.5-3). S2, salt gypsum and bittern are mixed in dechlorination reactor 21. After mixing, an alkaline compound is added and the mixture is reacted for 1 to 3 hours under continuous stirring, pH 9.0 to 11.0 and temperature 40℃ to 80℃. S3. The reacted slurry obtained in S2 is transported to the controlled aging chamber 22 and aged for 3 to 7 days at a temperature of 25℃~60℃ and a humidity of 60%~85%. S4. Pump the aged slurry into the separation and washing module 3 for solid-liquid separation and multi-stage countercurrent washing to obtain filter cake; S5. The filter cake obtained in S4 is conveyed to the post-processing module 4 and dried at 80℃~120℃ until the moisture content is less than 10%, and then pulverized to 60~100 mesh to obtain the calcium magnesium sulfur composite product.

[0046] Preferably, the alkaline compound includes any one or a combination of calcium oxide, calcium hydroxide, or magnesium oxide.

[0047] Preferably, the calcium-magnesium-sulfur composite product has a pH value of 8.5 to 10.5, a chloride ion content of ≤3%, and contains citrate-soluble calcium oxide, citrate-soluble magnesium oxide, and sulfur.

[0048] Preferably, in step S2, during the first third of the aging time, the rotation speed of the material distribution component 222 is 5 to 10 rpm; during the latter two-thirds of the aging time, the rotation speed of the material distribution component 222 is 2 to 4 rpm.

[0049] Preferably, in step S2, the temperature and humidity control component 223 inputs agitation hot air every 10 to 60 minutes. Specifically, the agitation hot air is only used to agitate the bottom slurry. If the temperature and humidity change, the interval of agitation hot air is recalculated after inputting the mixed airflow.

[0050] The present invention also provides an application of the calcium-magnesium-sulfur composite product prepared by the preparation method described above in soil improvement.

[0051] Example 1 S1. Place the salt gypsum into the pretreatment module 1 for crushing. Crush the salt gypsum to 100 mesh using a salt gypsum crusher. Then, feed the crushed salt gypsum and bittern into the dechlorination reactor 21 at a mass ratio of 1:1.5. S2, salt gypsum and bittern are mixed in dechlorination reactor 21. After mixing, calcium oxide and calcium hydroxide are added and reacted for 2 hours under continuous stirring, pH 10.5 and temperature 60℃. S3. The reacted slurry obtained in S2 is transported to the controllable aging chamber 22 and aged for 5 days at a temperature of 30±1℃ and a humidity of 75%. During the first 2 days of aging, the rotation speed of the material distribution component 222 is 6 rpm, and the temperature and humidity control component 223 inputs hot air for disturbance every 15 minutes. During the next 3 days of aging, the rotation speed of the material distribution component 222 is 3 rpm, and the temperature and humidity control component 223 inputs hot air for disturbance every 45 minutes.

[0052] S4. Pump the aged slurry into the separation and washing module 3 for solid-liquid separation and multi-stage countercurrent washing to obtain filter cake; S5. The filter cake obtained in S4 is conveyed to the post-processing module 4, dried at 105℃, and then pulverized to 80 mesh to obtain the calcium-magnesium-sulfur composite product. The obtained calcium-magnesium-sulfur composite product has a chlorine content of 1.8%, a citrate-soluble CaO content of 28%, a citrate-soluble MgO content of 16%, and a pH of 9.9.

[0053] Example 2 S1. Place the salt gypsum into the pretreatment module 1 for crushing. Crush the salt gypsum to 150 mesh using a salt gypsum crusher. Then, feed the crushed salt gypsum and bittern into the dechlorination reactor 21 at a mass ratio of 1:0.8. S2, salt gypsum and bittern are mixed in dechlorination reactor 21. After mixing, calcium oxide and calcium hydroxide are added and reacted for 1.5 hours under continuous stirring, pH 9.8 and temperature 50℃. S3. The slurry obtained after reaction in S2 is transported to the controllable aging chamber 22 and aged for 3 days at a temperature of 40±1℃ and a humidity of 65%. S4. Pump the aged slurry into the separation and washing module 3 for solid-liquid separation and multi-stage countercurrent washing to obtain filter cake; S5. The filter cake obtained in S4 is conveyed to the post-processing module 4, dried at 90℃, and then pulverized to 60 mesh to obtain the calcium-magnesium-sulfur composite product. The obtained calcium-magnesium-sulfur composite product has a chlorine content of 1.2%, a citrate-soluble CaO content of 32%, a citrate-soluble MgO content of 12%, and a pH of 10.3.

[0054] Example 3 The product from Example 1 was applied to an acidic red soil orchard in southern China (100 kg per mu). The results showed that the soil pH increased from 4.8 to 5.6, the orchard yield increased by 16%, and the quality was significantly improved. The effect was better than that of a physical mixture of commercial lime and magnesium sulfate with the same nutrients.

[0055] It should be noted that the specific parameters or some commonly used reagents in the above embodiments are specific or preferred embodiments under the concept of the present invention, and not limitations thereof; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

[0056] In addition, unless otherwise specified, the raw materials used may be commercially available products in the field, or prepared by conventional methods in the field.

[0057] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0058] Although this document uses terms such as reaction aging module, dechlorination reactor, and controlled aging chamber frequently, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any kind of additional limitation would contradict the spirit of the invention. The terms "first," "second," etc. (if present), in the description and claims of the embodiments of the invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A calcium-magnesium-sulfur composite system for the recycling of salt field by-products, characterized in that, include: The pretreatment module (1) is used to crush salt gypsum and transport the crushed salt gypsum and stored bittern in a proportional manner. The reaction aging module (2), located at the rear end of the pretreatment module (1), includes a dechlorination reactor (21) and a controllable aging chamber (22) connected in series. The dechlorination reactor (21) performs an alkali reaction on the bittern supplied by the pretreatment module (1). The controllable aging chamber (22) includes an aging body (221), a material distribution component (222), a temperature and humidity control component (223), and a detection component. The aging body (221) has an aging cavity (2211) inside, and the material distribution component (222) is positioned along the length of the aging cavity (2211). The temperature and humidity control components are distributed and arranged in the middle of the aging chamber (2211) in a 24-degree direction, the temperature and humidity control components (223) are arranged at the bottom of the aging chamber (2211), and the detection components are distributed at intervals in the aging chamber (2211). The temperature and humidity control components (223) are used to deliver steam and hot air into the aging chamber (2211) from bottom to top. The detection components are used to detect the temperature and humidity of each area in the aging chamber (2211). The detection components are electrically connected to the material distribution components (222) and the temperature and humidity control components (223). The separation and washing module (3) is located at the rear end of the reaction aging module (2) and is used to wash and filter the slurry that has been aged in the controllable aging chamber (22). The post-processing module (4) is used to dry and pulverize the filter cake after it has been washed and filtered by the separation and washing module (3).

2. The calcium-magnesium-sulfur composite system for the reuse of salt field by-products according to claim 1, characterized in that: The material distribution assembly (222) includes a drive motor (2221), a drive rod (2222), a fixed frame (2223), and a swing plate (2224). One end of the drive rod (2222) is connected to the drive motor (2221), and the other end of the drive rod (2222) is rotatably connected to the inner wall of the aging body (221). Multiple fixed frames (2223) are arranged around the drive rod (2222) at intervals. The fixed frames (2223) extend from the drive rod (2222) in a direction away from the drive rod (2222), and the swing plate (2224) is embedded in the fixed frame (2223).

3. The calcium-magnesium-sulfur composite system for the reuse of salt field by-products according to claim 2, characterized in that: The swing plate (2224) is rotatably connected to the fixed frame (2223) away from the drive rod (2222) via a swing pivot (2225). The fixed frame (2223) is provided with a blocking inclined wall (2226), which is located on both sides of the swing pivot (2225). The blocking inclined wall (2226) is used to limit the rotation angle of the swing plate (2224).

4. The calcium-magnesium-sulfur composite system for the recycling of salt field by-products according to claim 3, characterized in that: Each of the fixed frames (2223) is provided with a plurality of the swing plates (2224).

5. The calcium-magnesium-sulfur composite system for the reuse of salt field by-products according to claim 1, characterized in that: The temperature and humidity control component (223) includes a partition plate (2231), a steam pipe (2232), a hot air pipe (2233), and a mixing pipe (2234). The partition plate (2231) is located at the bottom of the aging chamber (2211). The steam pipe (2232) and the hot air pipe (2233) are located below the partition plate (2231). The mixing pipe (2234) is provided between the partition plate (2231) and the steam pipe (2232). The partition plate (2231) is provided with a spray nozzle (2237) corresponding to the mixing pipe (2234). The mixing pipe (2234) is connected to the spray nozzle (2237).

6. The calcium-magnesium-sulfur composite system for the reuse of salt field by-products according to claim 5, characterized in that: The mixing pipe (2234) has two sets of mixing channels (22341). The initial ends of the two sets of mixing channels (22341) are connected to the steam pipe (2232) and the hot air pipe (2233), respectively. The two sets of mixing channels (22341) converge and separate alternately in the mixing pipe (2234) at least twice before connecting to the injection port (2237).

7. The calcium-magnesium-sulfur composite system for the reuse of salt field by-products according to claim 5, characterized in that: The temperature and humidity control component (223) further includes a guide turbine fan (2235) and a distribution cavity (2236). The guide turbine fan (2235) is arranged in an array above the spacer plate (2231). The injection port (2237) is arranged around the rotation axis of the guide turbine fan (2235). The distribution cavity (2236) is arranged below the spacer plate (2231) corresponding to the guide turbine fan (2235). The injection port (2237) is connected to the distribution cavity (2236). The distribution cavity (2236) is connected to the mixing pipe (2234).

8. The calcium-magnesium-sulfur composite system for the reuse of salt field by-products according to claim 7, characterized in that: The steam pipe (2232) and the hot air pipe (2233) are respectively connected to the mixing pipe (2234) through the control pipe (2238). The control pipe (2238) is equipped with a solenoid valve (2239), which is electrically connected to the detection component.

9. A method for preparing a calcium-magnesium-sulfur composite system for the reuse of salt field by-products as described in any one of claims 1 to 8, characterized in that, The steps are as follows: S1. Place the salt gypsum into the pretreatment module (1) for crushing. Crush the salt gypsum to 80-200 mesh using a salt gypsum crusher. Then, feed the crushed salt gypsum and bittern into the dechlorination reactor (21) at a mass ratio of 1:(0.5-3). S2, salt gypsum and bittern are mixed in the dechlorination reactor (21). After mixing, an alkaline compound is added and the mixture is reacted for 1 to 3 hours under continuous stirring, pH 9.0 to 11.0 and temperature 40°C to 80°C. S3. The slurry obtained after reaction in S2 is transported to a controllable aging chamber (22) and aged for 3 to 7 days at a temperature of 25℃ to 60℃ and a humidity of 60% to 85%. S4. The aged slurry is pumped into the separation and washing module (3) for solid-liquid separation and multi-stage countercurrent washing to obtain filter cake; S5. The filter cake obtained in S4 is transported to the post-processing module (4) and dried at 80℃~120℃ until the moisture content is less than 10%, and then crushed to 60~100 mesh to obtain the calcium magnesium sulfur composite product.

10. The application of a calcium-magnesium-sulfur composite product prepared by the method described in claim 9 in soil improvement.

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