A heat treatment device and method for synthesizing polyaluminum chloride from aluminum trichloride wastewater

Abstract

The present application relates to the technical field of chemical wastewater treatment, and particularly relates to a heat treatment device and method for synthesizing polyaluminum chloride from aluminum chloride wastewater. The heat treatment device for synthesizing polyaluminum chloride from aluminum chloride wastewater comprises a main body, a reaction cavity in the main body, a feeding pipe and an exhaust pipe on the top of the reaction cavity, a four-axis stirring mechanism on the top of the main body, a stirring motor, a transmission assembly and four stirring paddle groups, the stirring motor being drivingly connected to the stirring paddle groups through the transmission assembly, the stirring motor enabling the adjacent stirring paddle groups to rotate in opposite directions, a heating ring set outside the main body, and a rotary heat exchange mechanism extending upward from the bottom of the main body and located in the center of the reaction cavity, the rotary heat exchange mechanism being embedded in the middle of the four-axis stirring mechanism. The heat treatment device can make the aluminum chloride wastewater reach a controllable dynamic curing effect in the process of being synthesized into polyaluminum chloride, thereby effectively improving the treatment effect and efficiency.

Description

Technical Field

[0001] This invention relates to the field of chemical wastewater treatment technology, and in particular to a heat treatment device and method for synthesizing polyaluminum chloride from aluminum trichloride wastewater. Background Technology

[0002] Chemical companies' production wastewater contains a large amount of acidic and alkaline substances or other compounds. Different types of wastewater need to be transported to qualified treatment plants for treatment. This results in high treatment costs and requires chemical companies to store the wastewater, incurring storage costs. Furthermore, untimely delivery during large-scale production may restrict production continuity.

[0003] Therefore, companies have begun to recycle and reuse chemical wastewater internally, recycling various elements in the wastewater or producing by-products. Aluminum trichloride wastewater, a common wastewater from chemical companies, is characterized by high oil content, high acidity, and the presence of organic matter. Its Al2O3 content, after conversion, is typically 7% to 11%. To utilize the aluminum element in aluminum trichloride wastewater, some companies have begun to use aluminum ash or bauxite as raw materials to neutralize the aluminum trichloride wastewater, thereby obtaining polyaluminum chloride.

[0004] However, static curing requires a long curing time, resulting in low treatment efficiency. Dynamic curing, on the other hand, currently available wastewater treatment equipment can only perform simple heating and stirring of aluminum trichloride wastewater. It is difficult to control the stirring rate during curing. Excessive stirring rate or too large a stirring area will break up the polyaluminum chloride in the flocs, affecting the formation of polyaluminum chloride and resulting in poor curing effect, which is difficult to meet the production needs of enterprises. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a heat treatment device and treatment method for the synthesis of polyaluminum chloride from aluminum trichloride wastewater, thereby solving the problems that existing wastewater treatment equipment cannot accelerate the maturation process of aluminum trichloride wastewater, has low treatment efficiency, and poor treatment effect.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater, comprising:

[0007] The main body has a reaction cavity inside, with a feed pipe and an exhaust pipe at the top of the reaction cavity and a discharge pipe at the bottom of the reaction cavity;

[0008] The four-axis stirring mechanism is located on the top of the main body and includes a stirring motor, a transmission assembly, and four stirring blades. The stirring motor is connected to the stirring blades through the transmission assembly, and the stirring motor causes adjacent stirring blades to rotate synchronously in opposite directions. In the vertical direction, the projected area of ​​the stirring range of the blades of the stirring blades of the stirring blades of the stirring blades of the adjacent stirring blades partially overlaps with the projected area of ​​the stirring range of the blades of the adjacent stirring blades.

[0009] A heating ring, located on the outside of the main body, is used to heat the main body;

[0010] The rotary heat exchange mechanism extends upward from the bottom of the main body and is located in the center of the reaction cavity. The rotary heat exchange mechanism is embedded in the middle of the four-axis stirring mechanism. The rotary heat exchange mechanism rotates around its own axis to guide and heat the liquid in the reaction cavity. In the vertical direction, the projection area of ​​the rotary heat exchange mechanism does not coincide with the projection area of ​​the stirring range of the impeller blades of the stirring paddle assembly.

[0011] In this embodiment, the transmission assembly includes a driving bevel gear, a driven bevel gear assembly, a first reverse transmission assembly, and a second reverse transmission assembly. The driving bevel gear is driven to the output end of the stirring motor. The driven bevel gear assembly includes a first driven bevel gear and a second driven bevel gear, which mesh on both sides of the driving bevel gear. The first driven bevel gear is driven to the first reverse transmission assembly, and the second driven bevel gear is driven to the second reverse transmission assembly. The first reverse transmission assembly and the second reverse transmission assembly drive two stirring paddle assemblies, which rotate in opposite directions.

[0012] In this embodiment, the first reverse transmission component includes two sets of first transmission bevel teeth and a first transmission screw. The first transmission bevel teeth are disposed on both sides of the first driven bevel teeth and drivenly connected to the first transmission screw. The first transmission screw is drivenly connected to a stirring paddle assembly through a first transmission worm gear.

[0013] The second reverse transmission component includes two sets of second transmission bevel teeth and a second transmission screw. The second transmission bevel teeth are arranged on both sides of the second driven bevel teeth and drivenly connected to the second transmission screw. The second transmission screw is drivenly connected to a stirring paddle assembly through a second transmission worm gear.

[0014] The threads of the first and second transmission screws are in opposite directions.

[0015] In this embodiment, the stirring paddle assembly includes a stirring shaft and several layers of stirring blades, with each layer of stirring blades having at least 4 stirring blades.

[0016] In this embodiment, the agitator blades of the agitator assembly extend into the agitator blade layer of the adjacent agitator assembly.

[0017] In this embodiment, the stirring blades of the stirring paddle assembly are not at the same height as the stirring blades of the adjacent stirring paddle assembly.

[0018] In this embodiment, the rotary heat exchange mechanism includes a rotary motor, a rotary base, and a heat exchange plate assembly. The output end of the rotary motor passes through the rotary base and is drivenly connected to the heat exchange plate assembly. The heat exchange plate assembly is embedded in the rotary base and is rotatably connected to the rotary base.

[0019] The rotating base has an annular medium output cavity and a medium input cavity from the outside to the inside. The heat transfer medium is input into the medium input cavity through the delivery pipe or output from the medium output cavity. The heat exchange plate assembly is provided with a medium flow channel. The medium outlet and medium inlet of the medium flow channel are connected to the annular openings of the medium output cavity and the medium input cavity, respectively.

[0020] In this embodiment, the heat exchange plate assembly includes a rotating base and four heat exchange plates that are intersected in a cross shape. There are four sets of medium flow channels corresponding to the heat exchange plates. Each set of medium flow channels extends upward from the bottom outer side of the rotating base and reciprocates in the horizontal direction. After the medium flow channel extends to the top of the medium flow channel, it extends laterally to the center of the heat exchange plate and then extends vertically downward from the center of the heat exchange plate to the bottom of the rotating base.

[0021] In this embodiment, the heat spreader is provided with flow holes, which are arranged to avoid the medium flow channel.

[0022] This invention also provides a heat treatment method for synthesizing polyaluminum chloride from aluminum trichloride wastewater, employing any of the heat treatment devices described above for synthesizing polyaluminum chloride from aluminum trichloride wastewater, and the steps are as follows:

[0023] S1. After simple filtration, the wastewater to be treated is fed into the heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater. The four-shaft stirring mechanism is turned on and the wastewater to be treated is heated to 50℃~60℃ through the heating ring and the rotary heat exchange mechanism.

[0024] S2. Put the four-axis stirring mechanism and the rotary heat exchange mechanism into a high-speed stirring state, add calcium aluminate powder, the mass ratio of the wastewater to be treated to calcium aluminate powder is 9 to 12:1, the high-speed stirring state is maintained for 25 to 40 minutes, and the high-speed stirring rate is 100 to 300 rpm.

[0025] S3. After stirring, the heating ring and rotary heat exchanger heat the mixed wastewater at 90℃~95℃ for 2~3 hours to mature. During the maturation process, the rotary heat exchanger continuously enters a low-speed stirring state with a rotation speed of 15~50rpm. The four-axis stirring mechanism stirs at low speed for 5 minutes every 25 minutes. The ratio of the rotation speed of the four-axis stirring mechanism to the rotation speed of the rotary heat exchanger is 0.2~1:1.

[0026] S4. After maturation, the reaction mixture is output from the heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater and filtered to obtain the target PAC (polyaluminum chloride solution) product.

[0027] The beneficial effects of this invention are as follows:

[0028] In current aluminum trichloride wastewater treatment processes, aluminum ash or bauxite are typically used as neutralizing materials. After being added to the aluminum trichloride wastewater for a static aging reaction, polyaluminum chloride is obtained. However, the static aging process requires a long aging time, resulting in low treatment efficiency. Furthermore, due to the presence of organic impurities in the aluminum trichloride wastewater, the overall viscosity is high, making it difficult for conventional treatment equipment to fully mix the wastewater with aluminum ash or bauxite. This can lead to uneven distribution of the aluminum ash or bauxite. Replacing aluminum ash or bauxite with calcium aluminate powder may further exacerbate the uneven distribution, potentially causing excessive local temperature fluctuations and decomposing some of the polyaluminum chloride. This negatively impacts the treatment efficiency and effectiveness of the aluminum trichloride wastewater, ultimately resulting in insufficient wastewater treatment performance of the final polyaluminum chloride product.

[0029] Therefore, this invention incorporates a four-axis stirring mechanism within the reaction cavity. A drive motor powers four sets of stirring paddles, which rotate synchronously via a transmission assembly, with adjacent paddle sets rotating in opposite directions. This creates turbulent flow within the reaction cavity, effectively eliminating dead zones at the cavity edges and preventing laminar flow. This avoids the agglomeration of calcium aluminate powder, ensuring thorough mixing of the aluminum trichloride wastewater and calcium aluminate powder, thus guaranteeing effective treatment. Furthermore, the turbulent flow allows for better heat exchange within the reaction cavity, ensuring precise temperature control.

[0030] However, if only a four-axis stirring mechanism is used, the rotation of the four sets of impellers during the stirring process causes the liquid to collide and converge at the center of the four-axis stirring mechanism, which may create vortices. This can lead to the accumulation of calcium aluminate powder in the center, or make it difficult for the liquid in the center to flow to the outside of the reaction cavity, resulting in a dead zone in the overall flow of the reaction liquid, affecting the mixing and temperature control. At the same time, during the maturation process, the excessive stirring effect of the four-axis stirring mechanism can break down the molecular chains of polyaluminum chloride. Even at low speeds, the four sets of impellers cause the reaction liquid to converge and collide from the edge to the center, resulting in excessive agglomeration. This not only fails to achieve the dynamic maturation effect, but also affects the quality of the final product.

[0031] Therefore, the present invention sets a rotary heat exchange mechanism in the center of the reaction cavity. The rotary heat exchange mechanism extends upward from the bottom of the main body into the middle of the four-axis stirring mechanism. That is, the rotary heat exchange mechanism is set in the dead corner of the stirring area of ​​the four sets of stirring paddles. Through the rotation of the rotary heat exchange mechanism itself, the liquid in the central area is guided to the outside of the reaction cavity by centrifugal force. This not only eliminates the vortex that may appear in the center, but also allows for low-speed rotation during the maturation process, forming a laminar flow. This prevents the liquid in the reaction cavity from being dispersed while flowing slowly, thereby improving the maturation efficiency and lengthening the final polyaluminum chloride molecular chains.

[0032] Furthermore, the rotary heat exchange mechanism can work in conjunction with the heating jacket to heat the reaction liquid simultaneously from the center and the outer periphery of the reaction cavity, thereby accelerating the heat transfer rate. This not only ensures the uniformity and accuracy of heating but also effectively reduces energy costs.

[0033] Furthermore, the method for treating aluminum trichloride wastewater to synthesize polyaluminum chloride provided by this invention involves initially filtering the aluminum trichloride wastewater and then introducing it into a heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater. A four-axis stirring mechanism and a rotary heat exchanger work together to thoroughly stir the aluminum trichloride wastewater and calcium aluminate powder at a set temperature. After entering the maturation stage, a rotary heat exchanger that can rotate and heat guides the reaction liquid to rotate slowly, forming laminar flow, accelerating the formation of polyaluminum chloride and extending its molecular weight. The intermittently rotating four-axis stirring mechanism then slowly mixes the reaction liquid within a set time, preventing edge settling and clumping. Simultaneously, the four-axis stirring mechanism guides the reaction liquid from the edges of the reaction cavity to the central region for thorough heat exchange, ensuring accurate, sensitive, uniform, and stable temperature control within the reaction cavity. This not only results in high treatment efficiency and significantly reduced maturation time but also guarantees a high content of effective components in the obtained polyaluminum chloride solution, demonstrating excellent wastewater treatment performance.

[0034] 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

[0035] Figure 1 This is a perspective view of an embodiment of the present invention;

[0036] Figure 2 for Figure 1 Top view;

[0037] Figure 3 for Figure 2 Cross-sectional view at point AA;

[0038] Figure 4 for Figure 3 Enlarged view of a section at point B in the middle;

[0039] Figure 5 for Figure 3 Enlarged view of a section at point E in the middle;

[0040] Figure 6 This is a three-dimensional schematic diagram of a four-axis stirring mechanism in one embodiment of the present invention;

[0041] Figure 7 for Figure 6 A magnified view of a section at point D;

[0042] Figure 8 for Figure 6 Top view;

[0043] Figure 9 This is a three-dimensional schematic diagram of a rotary heat exchange mechanism in one embodiment of the present invention;

[0044] Figure 10 This is an exploded view of a rotary heat exchange mechanism according to an embodiment of the present invention;

[0045] Figure 11 for Figure 10 The main view;

[0046] Figure 12 for Figure 11 Cross-sectional view at point C;

[0047] Figure 13 This is a perspective view of the rotating base in one embodiment of the present invention.

[0048] Label Explanation:

[0049] 1. Main body; 11. Reaction cavity; 12. Feed pipe; 13. Exhaust pipe; 14. Discharge pipe; 15. Rubber layer; 2. Four-axis stirring mechanism; 21. Stirring motor; 22. Transmission assembly; 221. Driving bevel gear; 222. Driven bevel gear assembly; 2221. First driven bevel gear; 2222. Second driven bevel gear; 223. First reverse transmission assembly; 2231. First transmission bevel gear; 2232. First transmission screw; 2233. First transmission worm gear; 224. Second reverse transmission assembly; 2241. Second transmission bevel gear; 2242. 2243 Second conduction screw; 23 Agitator assembly; 231 Agitator shaft; 232 Agitator blades; 24 Protective shell; 241 Connecting bolt; 242 Extension; 243 Fitting protrusion; 244 Sealing ring plate; 3 Heating ring sleeve; 4 Rotary heat exchange mechanism; 41 Rotary motor; 42 Rotary base; 421 Medium output chamber; 422 Medium input chamber; 423 Conveying pipe; 424 Annular opening; 43 Heat exchange plate assembly; 431 Rotary base; 432 Heat spreader plate; 433 Medium flow channel. Detailed Implementation

[0050] 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.

[0051] 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.

[0052] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0053] Please refer to Figures 1 to 12 A heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater, comprising:

[0054] The main body 1 has a reaction cavity 11 inside. The top of the reaction cavity 11 is provided with a feed pipe 12 and an exhaust pipe 13, and the bottom of the reaction cavity 11 is provided with a discharge pipe 14.

[0055] The four-axis stirring mechanism 2 is located on the top of the main body 1 and includes a stirring motor 21, a transmission assembly 22 and four stirring blade groups 23. The stirring motor 21 is driven to connect with the stirring blade groups 23 through the transmission assembly 22. The stirring motor 21 causes adjacent stirring blade groups 23 to rotate synchronously in opposite directions. In the vertical direction, the projected area of ​​the stirring range of the blades of the stirring blade group 23 partially overlaps with the projected area of ​​the stirring range of the blades of the adjacent stirring blade group 23.

[0056] The heating ring 3 is set outside the main body 1 and is used to heat the main body 1.

[0057] The rotary heat exchange mechanism 4 extends upward from the bottom of the main body 1 and is located in the center of the reaction cavity 11. The rotary heat exchange mechanism 4 is embedded in the middle of the four-axis stirring mechanism 2. The rotary heat exchange mechanism 4 rotates around its own axis to guide and heat the liquid in the reaction cavity 11. In the vertical direction, the projection area of ​​the rotary heat exchange mechanism 4 does not coincide with the projection area of ​​the stirring range of the blades of the stirring paddle assembly 23.

[0058] Specifically, in the vertical direction, the axes of the four mixing blade groups 23 are arranged in a rectangular shape. The mixing ranges of the four mixing blade groups 23 partially overlap each other. Furthermore, since the adjacent mixing blade groups 23 rotate synchronously in opposite directions, the mixing blade groups 23 will not interfere with the operation of other mixing blade groups 23 in the overlapping area, thus ensuring the mixing effect while avoiding damage to the four-axis mixing mechanism 2.

[0059] Specifically, the rotary heat exchange mechanism 4 is located at the junction center of the four stirring paddle groups 23, and does not come into contact with the stirring paddle groups 23, further ensuring that the four-axis stirring mechanism 2 and the rotary heat exchange mechanism 4 can operate normally.

[0060] Specifically, the heating ring 3 is equipped with a heating medium inlet pipe and a heating medium outlet pipe. Those skilled in the art can adjust the temperature of the heating ring 3 by inputting heating media of different temperatures, thereby adjusting the temperature of the liquid in the reaction cavity 11. Furthermore, an electric heating tube is provided inside the heating ring 3.

[0061] Since there are overlapping mixing areas between the mixing paddle groups 23, in order to ensure that the mixing paddle groups 23 do not collide when rotating, it is necessary to use the transmission component 22 to keep the rotation speed of each mixing paddle group 23 consistent. Therefore, in this embodiment, the transmission assembly 22 includes an active bevel gear 221, a driven bevel gear assembly 222, a first reverse transmission assembly 223, and a second reverse transmission assembly 224. The active bevel gear 221 is driven to the output end of the stirring motor 21. The driven bevel gear assembly 222 includes a first driven bevel gear 2221 and a second driven bevel gear 2222. The first driven bevel gear 2221 and the second driven bevel gear 2222 are respectively engaged on both sides of the active bevel gear 221. The first driven bevel gear 2221 is driven to the first reverse transmission assembly 223, and the second driven bevel gear 2222 is driven to the second reverse transmission assembly 224. The first reverse transmission assembly 223 and the second reverse transmission assembly 224 drive two stirring paddle assemblies 23, and the two stirring paddle assemblies 23 driven by the first reverse transmission assembly 223 and the second reverse transmission assembly 224 rotate in opposite directions. With this configuration, the first driven bevel teeth 2221 and the second driven bevel teeth 2222 meshing on both sides of the driving bevel teeth 221 cause the first reverse transmission component 223 and the second reverse transmission component 224 to rotate in opposite directions. The first reverse transmission component 223 and the second reverse transmission component 224 can use a combination of worm gears and worm shafts or gear sets with the same transmission ratio to further drive the agitator assembly 23, ensuring synchronous reverse rotation.

[0062] To ensure sufficient mixing space among the four agitator groups 23 and to prevent contact between the shafts of other agitator groups 23 when they rotate, the first reverse transmission assembly 223 includes two sets of first transmission bevel teeth 2231 and a first transmission screw 2232. The first transmission bevel teeth 2231 are located on both sides of the first driven bevel teeth 2221 and are drivenly connected to the first transmission screw 2232. The first transmission screw 2232 is connected to one agitator group 23 through a first transmission worm gear 2233.

[0063] The second reverse transmission component 224 includes two sets of second transmission bevel teeth 2241 and a second transmission screw 2242. The second transmission bevel teeth 2241 are disposed on both sides of the second driven bevel teeth 2222 and are drivenly connected to the second transmission screw 2242. The second transmission screw 2242 is connected to a stirring paddle assembly 23 through a second transmission worm gear 2243.

[0064] The thread directions of the first conductive screw 2232 and the second conductive screw 2242 are opposite.

[0065] Specifically, the back of the first driven bevel tooth 2221 and the second driven bevel tooth 2222 are provided with transmission bevel teeth, and the first transmission bevel tooth 2231 and the second transmission bevel tooth 2241 respectively mesh with the transmission bevel teeth on the back of the first driven bevel tooth 2221 or the second driven bevel tooth 2222.

[0066] Specifically, the first conductive screw 2232 can be a right-hand screw, the second conductive screw 2242 can be a left-hand screw, and the first conductive worm gear 2233 and the second conductive worm gear 2243 are correspondingly set with the first conductive screw 2232 and the second conductive screw 2242.

[0067] To ensure that the reaction liquid in the reaction cavity 11 can be fully stirred from top to bottom, in this embodiment, the stirring paddle assembly 23 includes a stirring shaft 231 and several layers of stirring blades 232, with each layer of stirring blades 232 having at least 4 stirring blades.

[0068] Preferably, each stirring blade layer 232 has 6 stirring blades, and each stirring blade assembly 23 has 6 to 8 stirring blade layers 232. Furthermore, the liquid within the reaction cavity 11 can circulate from bottom to top or from top to bottom under the action of stirring blade assemblies 23 with different rotation directions. Specifically, those skilled in the art can adjust the angle of the stirring blades at different positions in each stirring blade layer 232 as needed, without specific limitations.

[0069] In this embodiment, the impeller blades of the impeller assembly 23 extend into the impeller layer 232 of the adjacent impeller assembly 23. Preferably, the angle between the impeller blades and the impeller blades of the adjacent impeller assembly 23 is 15° to 60°.

[0070] To further ensure that the four-axis stirring mechanism 2 does not cause damage due to mutual impact during stirring, in this embodiment, the stirring blade layer 232 of the stirring paddle group 23 is not at the same height as the stirring blade layer 232 of its adjacent stirring paddle group 23. Furthermore, this arrangement can further avoid excessive collision of the reaction liquid at the center position when the four-axis stirring mechanism 2 rotates intermittently during the maturation stage, reduce the fragmentation of polyaluminum chloride, extend the molecular chain of polyaluminum chloride, and thus improve the flocculation and purification effect of the product.

[0071] To prevent external dust, moisture, and other substances from affecting the operation of the transmission components, in this embodiment, the four-axis stirring mechanism 2 also includes a protective housing 24. The protective housing 24 is disposed on the top of the main body 1, forming a protective cavity with the main body 1. The transmission component 22 is disposed within the protective cavity, and the stirring motor 21 is disposed on the top of the protective housing 24. The output end of the protective housing 24 extends through the protective housing 24 into the protective cavity and is drivenly connected to the transmission component 22. The protective housing 24 is fixedly connected to the top of the main body 1 by connecting bolts 241.

[0072] Because the stirring motor 21 is located at the top of the protective housing 24, and it needs to drive the transmission assembly 22 and four stirring paddles, the required power results in a large overall weight of the stirring motor 21. This makes the entire four-axis stirring mechanism 2 top-heavy. During operation, the stirring motor 21 may cause a slight shift in the center of gravity, resulting in the protective housing 24 being subjected to tilting forces in different directions. This leads to excessive axial force on the connecting bolts 241, causing them to loosen over time. To address this, an extension 242 is provided at the bottom of the protective housing 24, extending along the outer surface of the top of the main body 1. The connecting bolts 241 are mounted on this extension 242. After installation, the extension 242 abuts against the top of the main body 1, significantly increasing the support and contact surface between the protective housing 24 and the main body 1. This allows the force of the stirring motor 21 to be evenly transmitted to the main body 1, thereby improving the overall service life.

[0073] After the protective shell 24 is installed, the reaction force of the torque received by the stirring motor 21 when driving the transmission component 22 will be directly transmitted to the protective shell 24, causing the connecting bolt 241 to be subjected to lateral shear force. During the curing stage, the stirring motor 21 needs to be started intermittently, and the instantaneous shear force brought by frequent starts further increases the load on the connecting bolt 241. Under long-term use, the connecting bolt 241 may break, causing the protective shell 24 to twist, which in turn causes the stirring motor 21 and the transmission component 22 to misalign. Therefore, several fitting protrusions 243 are provided at intervals below the extension 242. The main body 1 has an opening corresponding to the fitting protrusions 243, and the inner surface of the opening is provided with a rubber layer 15. The fitting protrusions 243 pass through the opening and enter the reaction cavity 11. At the same time, a sealing ring plate 244 is provided at the top of the reaction cavity 11 corresponding to the extension 242. The fitting protrusions 243 are fixedly connected to the sealing ring plate 244. After the sealing ring plate 244 is installed, it can not only prevent the liquid in the reaction cavity 11 from corroding the fitting protrusions 243.

[0074] Specifically, the sealing ring plate 244 is welded to the fitting protrusion 243 and the top of the reaction cavity 11 to ensure the airtightness of the reaction cavity 11. The sealing ring plate 244, the connecting bolt 241, and the extension 242 work together to form a clamping structure between the protective shell 24 and the main body 1. The protective shell 24 is fixedly supported on both the upper and lower sides of the main body 1, further ensuring the connection stability and safety of the overall device and effectively preventing damage to the device caused by the displacement of the stirring motor 21.

[0075] The rotary heat exchange mechanism 4 needs to perform heat exchange while being able to rotate on its own. In order to ensure that the heat exchange process can adapt to the rotation process, in this embodiment, the rotary heat exchange mechanism 4 includes a rotary motor 41, a rotary base 42 and a heat exchange plate assembly 43. The output end of the rotary motor 41 passes through the rotary base 42 and is drivenly connected to the heat exchange plate assembly 43. The heat exchange plate assembly 43 is embedded in the rotary base 42 and is rotatably connected to the rotary base 42.

[0076] The rotating base 42 has an annular medium output cavity 421 and a medium input cavity 422 arranged sequentially from the outside to the inside. The heat-conducting medium is input into the medium input cavity 422 through the delivery pipe 423 or output from the medium output cavity 421. The heat exchange plate assembly 43 is provided with a medium flow channel 433, and the medium outlet and medium inlet of the medium flow channel 433 are respectively connected to the annular openings 424 of the medium output cavity 421 and the medium input cavity 422. Specifically, since the heat exchange plate assembly 43 is a vertical plate structure, when the heat exchange plate assembly 43 rotates, it can agitate the reaction liquid in the reaction cavity 11 over a larger range compared to a stirring paddle. At the same time, the plate structure has a small shearing effect on the reaction liquid, which can effectively prevent the rotation during the ripening process from breaking the molecular chains of polyaluminum chloride, thereby improving the quality of the obtained polyaluminum chloride while ensuring dynamic stirring.

[0077] In this embodiment, the heat exchange plate assembly 43 includes a rotating base 431 and four heat spreaders 432 that are intersected in a cross shape. There are four sets of medium flow channels 433 corresponding to the heat spreaders 432. Each set of medium flow channels 433 extends upward from the outer bottom of the rotating base 431 and reciprocates in the horizontal direction. After the medium flow channel 433 extends to the top of the medium flow channel 433, it extends laterally to the center of the heat spreader 432 and then extends vertically downward from the center of the heat spreader 432 to the bottom of the rotating base 431.

[0078] Preferably, the heat spreader 432 is provided with flow-through holes (not shown in the figure), which are positioned to avoid the medium flow channel 433. With the flow-through holes provided, the obstruction of the reaction liquid by certain areas of the heat spreader 432 during low-speed rotation can be reduced. Part of the reaction liquid in the corresponding area can pass through the heat spreader 432 via the flow-through holes, forming a velocity difference in a localized area, thereby creating localized laminar flow and further enhancing the traction effect on polyaluminum chloride. Furthermore, the flow-through holes increase the heat exchange area, improving the heat exchange rate and heat exchange effect.

[0079] This invention also provides a heat treatment method for synthesizing polyaluminum chloride from aluminum trichloride wastewater, employing any of the heat treatment devices described above for synthesizing polyaluminum chloride from aluminum trichloride wastewater, and the steps are as follows:

[0080] S1. After simple filtration, the wastewater to be treated is fed into the heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater. The four-axis stirring mechanism 2 is turned on and the wastewater to be treated is heated to 50℃~60℃ through the heating ring 3 and the rotary heat exchange mechanism 4.

[0081] S2. Put the quadriaxial stirring mechanism 2 and the rotary heat exchange mechanism 4 into a high-speed stirring state, add calcium aluminate powder, the mass ratio of the wastewater to be treated to the calcium aluminate powder is 9 to 12:1, the high-speed stirring state lasts for 25 to 40 minutes, and the high-speed stirring speed is 100 to 300 rpm.

[0082] S3. After stirring, the heating ring 3 and the rotary heat exchange mechanism 4 heat the mixed wastewater at 90℃~95℃ for 2~3 hours to mature. During the maturation process, the rotary heat exchange mechanism 4 continuously enters a low-speed stirring state with a rotation speed of 15~50rpm. The four-axis stirring mechanism 2 stirs at low speed for 5 minutes every 25 minutes. The ratio of the rotation speed of the four-axis stirring mechanism 2 to the rotation speed of the rotary heat exchange mechanism 4 is 0.2~1:1.

[0083] S4. After maturation, the reaction mixture is output from the heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater and filtered to obtain the target PAC product.

[0084] Example 1

[0085] Raw materials: aluminum trichloride wastewater (Al2O3 content 7.5%, acidity 6%), calcium aluminate powder (industrial grade).

[0086] Processing steps:

[0087] S1. After simple filtration, the wastewater to be treated is fed into the heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater. The four-axis stirring mechanism 2 is turned on and the wastewater to be treated is heated to 55±2℃ through the heating ring 3 and the rotary heat exchange mechanism 4.

[0088] S2. Put the four-axis stirring mechanism 2 and the rotary heat exchange mechanism 4 into a high-speed stirring state, add calcium aluminate powder, the mass ratio of the wastewater to be treated to calcium aluminate powder is 10:1, the high-speed stirring state is maintained for 30 minutes, and the high-speed stirring speed is 200 rpm.

[0089] S3. After stirring, the heating ring 3 and the rotary heat exchange mechanism 4 heat the mixed wastewater at 92±1℃ for 2 hours to mature. During the maturation process, the rotary heat exchange mechanism 4 continuously enters a low-speed stirring state with a rotation speed of 20rpm, and the four-axis stirring mechanism 2 stirs at a low speed of 10rpm for 5 minutes every 25 minutes.

[0090] S4. After maturation, the reaction mixture is output from the heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater and filtered to obtain the target PAC product (Al2O3 content 9.8%).

[0091] The obtained PAC product was used in a wastewater treatment experiment:

[0092] Wastewater characteristics: turbidity 238 NTU, COD 14670 mg / L, suspended solids 267 mg / L, pH 4. PAC dosage: 1 L / ton of raw water. Treatment results are shown in Table 1.

[0093] Table 1 Wastewater Treatment Results

[0094]

[0095] Example 2

[0096] Raw material: aluminum trichloride wastewater (Al2O3 content 8%, acidity 5%).

[0097] Processing steps: Same as in Example 1, except that the curing temperature is adjusted to 95±1℃, the curing time is 3 hours, the high-speed stirring rate of the four-axis stirring mechanism and the rotary heat exchange mechanism is 260 rpm, the low-speed stirring rate of the rotary heat exchange mechanism is 25 rpm, and the low-speed stirring rate of the four-axis stirring mechanism is 20 rpm, finally obtaining the PAC product (Al2O3 content 10.5%).

[0098] The obtained PAC product was used in a wastewater treatment experiment:

[0099] Wastewater properties: turbidity 369 NTU, COD 17640 mg / L, suspended solids 423 mg / L, pH 3, PAC dosage: 1.5L / ton of raw water, treatment effect is shown in Table 2.

[0100] Table 2 Treatment Results

[0101]

[0102] 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 the 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.

[0103] Although this document uses terms such as "body" and "reaction cavity" extensively, 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. Terms such as "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.

[0104] 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 heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater, characterized in that, include: The main body (1) has a reaction cavity (11) inside. The top of the reaction cavity (11) is provided with a feed pipe (12) and an exhaust pipe (13), and the bottom of the reaction cavity (11) is provided with a discharge pipe (14). The four-axis stirring mechanism (2) is located on the top of the main body (1) and includes a stirring motor (21), a transmission assembly (22) and four stirring paddle groups (23). The stirring motor (21) is driven to connect with the stirring paddle groups (23) through the transmission assembly (22). The stirring motor (21) causes adjacent stirring paddle groups (23) to rotate synchronously in opposite directions. In the vertical direction, the projection area of ​​the stirring range of the blades of the stirring paddle group (23) partially overlaps with the projection area of ​​the stirring range of the blades of the adjacent stirring paddle group (23). A heating ring (3) is disposed outside the main body (1) for heating the main body (1); The rotary heat exchange mechanism (4) extends upward from the bottom of the main body (1) and is located in the center of the reaction cavity (11). The rotary heat exchange mechanism (4) is embedded in the middle of the four-axis stirring mechanism (2). The rotary heat exchange mechanism (4) rotates around its own axis to guide and heat the liquid in the reaction cavity (11). In the vertical direction, the projection area of ​​the rotary heat exchange mechanism (4) does not coincide with the projection area of ​​the stirring range of the blades of the stirring paddle assembly (23).

2. The heat treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater according to claim 1, characterized in that: The transmission assembly (22) includes a driving bevel gear (221), a driven bevel gear assembly (222), a first reverse transmission assembly (223), and a second reverse transmission assembly (224). The driving bevel gear (221) is driven to the output end of the stirring motor (21). The driven bevel gear assembly (222) includes a first driven bevel gear (2221) and a second driven bevel gear (2222). The first driven bevel gear (2221) and the second driven bevel gear (2222) respectively mesh with the driving bevel gear (221). On both sides of the first driven bevel tooth (2221), the first driven bevel tooth (2222) is driven connected to the first reverse transmission component (223), and the second driven bevel tooth (2222) is driven connected to the second reverse transmission component (224). The first reverse transmission component (223) and the second reverse transmission component (224) drive the two stirring paddle groups (23) respectively, and the two stirring paddle groups (23) driven by the first reverse transmission component (223) and the second reverse transmission component (224) rotate in opposite directions.

3. The heat treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater according to claim 2, characterized in that: The first reverse transmission assembly (223) includes two sets of first transmission bevel teeth (2231) and a first transmission screw (2232). The first transmission bevel teeth (2231) are disposed on both sides of the first driven bevel teeth (2221) and drivenly connected to the first transmission screw (2232). The first transmission screw (2232) is connected to one of the stirring paddle groups (23) through a first transmission worm gear (2233). The second reverse transmission assembly (224) includes two sets of second transmission bevel teeth (2241) and a second transmission screw (2242). The second transmission bevel teeth (2241) are disposed on both sides of the second driven bevel teeth (2222) and drivenly connected to the second transmission screw (2242). The second transmission screw (2242) is connected to one of the stirring paddle groups (23) through a second transmission worm gear (2243). The thread direction of the first conductive screw (2232) is opposite to that of the second conductive screw (2242).

4. The heat treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater according to claim 1, characterized in that: The stirring paddle assembly (23) includes a stirring shaft (231) and several layers of stirring blades (232), each of the stirring blades (232) having at least 4 stirring blades.

5. The heat treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater according to claim 4, characterized in that: The agitator blade portion of the agitator assembly (23) extends into the agitator blade layer (232) of the adjacent agitator assembly (23).

6. The heat treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater according to claim 4, characterized in that: The stirring blade layer (232) of the stirring paddle group (23) is not at the same height as the stirring blade layer (232) of the adjacent stirring paddle group (23).

7. The heat treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater according to claim 1, characterized in that: The rotary heat exchange mechanism (4) includes a rotary motor (41), a rotary base (42), and a heat exchange plate assembly (43). The output end of the rotary motor (41) passes through the rotary base (42) and is drivenly connected to the heat exchange plate assembly (43). The heat exchange plate assembly (43) is embedded in the rotary base (42) and is rotatably connected to the rotary base (42). The rotating base (42) has an annular medium output cavity (421) and a medium input cavity (422) from the outside to the inside. The heat-conducting medium is input into the medium input cavity (422) through the delivery pipe (423) or output from the medium output cavity (421). The heat exchange plate group (43) is provided with a medium flow channel (433). The medium outlet and medium inlet of the medium flow channel (433) are respectively connected to the annular opening (424) of the medium output cavity (421) and the medium input cavity (422).

8. The heat treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater according to claim 7, characterized in that: The heat exchange plate assembly (43) includes a rotating base (431) and four heat exchange plates (432) that are intersected in a cross shape. The medium flow channels (433) are provided in four groups corresponding to the heat exchange plates (432). Each group of medium flow channels (433) extends upward from the bottom outer side of the rotating base (431) and reciprocates in the horizontal direction. After the medium flow channel (433) extends to the top of the medium flow channel (433), it extends laterally to the center of the heat exchange plate (432) and then extends vertically downward from the center of the heat exchange plate (432) to the bottom of the rotating base (431).

9. The heat treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater according to claim 8, characterized in that: The heat spreader (432) is provided with a flow through hole, which is arranged to avoid the medium flow channel (433).

10. A method for treating aluminum trichloride wastewater for the synthesis of polyaluminum chloride, characterized in that, The thermal treatment apparatus for synthesizing polyaluminum chloride from aluminum trichloride wastewater as described in any one of claims 1 to 9 is used, and the steps are as follows: S1. After simple filtration, the wastewater to be treated is fed into the heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater. The four-axis stirring mechanism (2) is turned on and the wastewater to be treated is heated to 50℃~60℃ through the heating ring (3) and the rotary heat exchange mechanism (4). S2. Put the four-axis stirring mechanism (2) and the rotary heat exchange mechanism (4) into a high-speed stirring state, add calcium aluminate powder, the mass ratio of the wastewater to be treated to the calcium aluminate powder is 9 to 12:1, the high-speed stirring state lasts for 25 to 40 minutes, and the high-speed stirring rate is 100 to 300 rpm. S3. After stirring, the heating ring (3) and the rotary heat exchange mechanism (4) heat the mixed wastewater at 90℃~95℃ for 2~3 hours to mature. During the maturation process, the rotary heat exchange mechanism (4) continuously enters a low-speed stirring state with a rotation speed of 15~50rpm. The four-axis stirring mechanism (2) stirs at low speed for 5 minutes every 25 minutes. The ratio of the rotation speed of the four-axis stirring mechanism (2) to the rotation speed of the rotary heat exchange mechanism (4) is 0.2~1:

1. S4. After maturation, the reaction mixture is output from the heat treatment device for synthesizing polyaluminum chloride from aluminum trichloride wastewater and filtered to obtain the target polyaluminum chloride solution.

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