A reaction device for preparing cryolite suspension by using fluorine waste water

Abstract

A kind of reaction equipment for preparing cryolite suspension using fluorine waste water, it includes ammonium fluoride production device and cryolite suspension production device, ammonium fluoride production device includes reaction kettle body, waste fluorine water storage tank, ammonia water storage tank and plate-and-frame filter press, cryolite suspension production device includes horizontal reaction tank body, aluminium hydroxide powder bin, sodium hydroxide powder bin and stirring mixing mechanism.The utility model has the advantages that: annular pipe and multiple ammonia water injection pipes form multiple-point uniform feeding at the bottom of reaction kettle body, ammonia water can contact with fluorosilicic acid in more dispersed form, increase contact area, speed up mass transfer process.Horizontal reaction tank body's axial mixing can reduce the settlement of aluminium hydroxide and sodium hydroxide, accelerate dissolution and reaction, and the concentration uniformity of reaction solution is significantly improved.

Description

Technical Field

[0001] This utility model relates to the field of cryolite production technology, specifically to a reaction device for preparing cryolite suspension using fluoride wastewater. Background Technology

[0002] Cryolite is an alkali metal fluoroaluminate, also known as sodium fluoroaluminate, with the molecular formula Na3AlF6. As a chemical product, cryolite is mainly used as a flux in the smelting of metallic aluminum, and can also be used as an insecticide for crops, an enamel opacifier, and a light-blocking agent and flux in glass and enamel production. Ammonium fluoride is one of the raw materials for producing cryolite. The traditional process for producing ammonium fluoride generally uses direct neutralization of hydrofluoric acid (HF) and liquid ammonia. Hydrofluoric acid is as expensive as 8,000 yuan / ton, and requires high-purity raw materials, resulting in raw material costs accounting for 60%-70% of the total cost. The waste fluoride water from the wet-process phosphoric acid process in the phosphate fertilizer industry comes from the washing water after phosphoric acid extraction. It has a high concentration of fluorosilicic acid (10%~15%) and is highly acidic. Replacing hydrofluoric acid with waste fluoride water in the production of ammonium fluoride can reduce the environmental pollution caused by waste fluoride water from the phosphate fertilizer industry. In the reaction of ammonium fluoride solution with aluminum hydroxide and sodium hydroxide, the stirring flow field in a vertical reactor is mainly radial and axial. When the height-to-diameter ratio is large, a concentration gradient of "thin at the top and thick at the bottom" easily occurs, affecting the reaction process and increasing the reaction time. Maintenance is also inconvenient due to the height. Utility Model Content

[0003] The purpose of this invention is to provide a reaction device for preparing cryolite suspension using fluoride wastewater, addressing the aforementioned deficiencies.

[0004] A reaction apparatus for preparing cryolite suspension using fluoride wastewater includes an ammonium fluoride production unit and a cryolite suspension production unit. The ammonium fluoride production unit includes a reaction vessel, a waste fluoride water storage tank, an ammonia water storage tank, and a plate and frame filter press. The cryolite suspension production unit includes a horizontal reaction tank, an aluminum hydroxide powder silo, a sodium hydroxide powder silo, and a stirring and mixing mechanism.

[0005] The reactor body has a waste fluoride water inlet on one side of its top, which is connected to the bottom of a waste fluoride water storage tank via a waste fluoride water delivery pipeline. A stirring motor is located at the center of the top of the reactor body, and the motor's shaft is connected to a stirring shaft extending into the reactor body. A stirring paddle assembly is mounted on the stirring shaft. A tail gas outlet is located on the other side of the top of the reactor body, connected to a tail gas delivery pipeline. A gas-liquid separator and a tail gas delivery fan are sequentially installed on the tail gas delivery pipeline. The bottom of the reactor body has a conical structure, and a discharge port with a discharge valve is located at the bottom end of the reactor body. The discharge port is connected to a conveyor... The pipeline and fluoroplastic diaphragm pump are connected to the feed inlet of the plate and frame filter press; the bottom of the reactor body is also equipped with an ammonia water inlet assembly, which includes an annular pipe and multiple ammonia water injection pipes evenly arranged in a clockwise direction inside the annular pipe. The multiple ammonia water injection pipes are all horizontally arranged and have outlets at the top. The lower part of the annular pipe is equipped with multiple support rods fixed to the bottom of the reactor body. The annular pipe is also equipped with an inlet interface connected to the ammonia water inlet pipe. The ammonia water inlet pipe passes through the reactor body and is connected to an ammonia water storage tank located on one side. The ammonia water inlet pipe is equipped with an inlet valve and an ammonia water inlet pump.

[0006] The horizontal reaction tank includes vertical plates on both side walls, an arc-shaped plate at the bottom, a cover plate at the top, and end caps at both ends. The mixing mechanism includes a mixing motor a and a mixing motor b respectively mounted on the end caps at both ends. The shafts of mixing motor a and mixing motor b are respectively connected to horizontal 316L stainless steel spiral shaft a and horizontal 316L stainless steel spiral shaft b located within the horizontal reaction tank. A cryolite suspension discharge port with a discharge valve is located at the center of the bottom of the arc-shaped plate. An ammonium fluoride solution inlet and an exhaust port are located in the middle of the cover plate. The outlet of the plate and frame filter press is connected to the ammonium fluoride solution inlet via an ammonium fluoride solution inlet pipe. The aluminum hydroxide powder silo and sodium hydroxide powder silo are located on both sides above the cover plate at the top of the horizontal reaction tank. The bottom of both the aluminum hydroxide powder silo and the sodium hydroxide powder silo are conical structures with a cone angle ≥70°. Vibration motors are installed on both sides of the bottom of the silo. The conical surface of the bottom of the silo is lined with a 316L stainless steel polished plate. The outlets of both the aluminum hydroxide powder silo and the sodium hydroxide powder silo are connected to the aluminum hydroxide inlet and the sodium hydroxide inlet on the cover plate via pneumatic butterfly valves and sealing flanges, respectively.

[0007] Preferably, the reactor body is made of 316L stainless steel and lined with polytetrafluoroethylene.

[0008] Preferably, there are six ammonia injection pipes, and the diameter of the ammonia injection pipes is 10-15 mm.

[0009] Preferably, the exhaust gas conveying pipe is made of PP material, and the end of the exhaust gas conveying pipe is connected to the inlet of the dilute sulfuric acid packed tower.

[0010] Preferably, the waste fluoride water delivery pipeline is equipped with a drain valve, and the end of the ammonia water inlet pipe is equipped with an inlet check valve.

[0011] Preferably, the outer wall of the reactor body is also provided with a cooling water jacket for cooling.

[0012] Preferably, the horizontal reaction tank is made of 316L stainless steel and lined with polytetrafluoroethylene, and a support frame is provided at the bottom of the horizontal reaction tank.

[0013] Preferably, the horizontal 316L stainless steel spiral shaft a and the horizontal 316L stainless steel spiral shaft b are located at the same height and rotate in opposite directions, and both of their surfaces are covered with a polytetrafluoroethylene layer.

[0014] Preferably, the exhaust port is connected to an exhaust pipe, the exhaust pipe is made of PP material, the exhaust pipe is equipped with a wire mesh demister, and the end of the exhaust pipe is connected to the air inlet of the dilute sulfuric acid packed tower.

[0015] Preferably, the side walls and bottom of the horizontal reaction tank are covered with heat transfer oil jackets.

[0016] The advantages of this invention are: the annular pipe and multiple ammonia injection pipes form a multi-point uniform feeding system at the bottom of the reactor. Compared with single-point feeding, ammonia can contact fluorosilicic acid in a more dispersed manner, increasing the contact area and accelerating the mass transfer process. The multiple ammonia injection pipes, evenly arranged clockwise inside the annular pipe, utilize fluid kinetic energy to drive the material into a turbulent state, reducing local concentration gradients and making the reaction more uniform.

[0017] Fluorosilicic acid (density approximately 1.3-1.4 g / cm³) typically has a higher density than ammonia (approximately 0.9 g / cm³). Adding ammonia from the bottom allows the low-density fluid to move upwards, creating counter-current convection with the fluorosilicic acid flowing downwards. This enhances the mixing effect and is more in line with the mass transfer logic of "density difference-driven convection" compared to adding the material from the top.

[0018] Axial mixing in a horizontal reaction tank can reduce the sedimentation of aluminum hydroxide and sodium hydroxide, accelerate dissolution and reaction, and significantly improve the uniformity of the reaction solution concentration compared to a vertical reaction device. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an ammonium fluoride production unit.

[0020] Figure 2 This is a schematic diagram of the bottom structure of the ammonia inlet assembly.

[0021] Figure 3 This is a schematic diagram of a cryolite suspension production device.

[0022] Figure 4 This is a side view of the cryolite suspension production unit. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of the embodiments of this utility model, it should be noted that if terms such as "upper," "lower," "inner," or "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use, they are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the utility model. Furthermore, if terms such as "first" or "second" appear in the description of this utility model, they are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0028] As shown in the attached figure, a reaction device for preparing cryolite suspension using fluoride wastewater includes an ammonium fluoride production device and a cryolite suspension production device. The ammonium fluoride production device includes a reaction vessel 1, a waste fluoride water storage tank 2, an ammonia water storage tank 3, and a plate and frame filter press 4. The cryolite suspension production device includes a horizontal reaction tank 31, an aluminum hydroxide powder silo 32, a sodium hydroxide powder silo 33, and a stirring and mixing mechanism.

[0029] The reactor body 1 has a waste fluoride water inlet 5 on one side of its top, which is connected to the bottom of the waste fluoride water storage tank 2 via a waste fluoride water delivery pipeline. A stirring motor 11 is located at the center of the top of the reactor body 1, and the rotating shaft of the stirring motor 11 is connected to a stirring shaft 12 extending into the reactor body 1. A stirring paddle assembly is mounted on the stirring shaft 12. A tail gas outlet is located on the other side of the top of the reactor body 1, and the tail gas outlet is connected to a tail gas delivery pipeline 6. A gas-liquid separator 7 and a tail gas delivery fan 8 are sequentially mounted on the tail gas delivery pipeline 6. The bottom of the reactor body 1 has a conical structure, and a discharge port 9 with a discharge valve is located at the bottom end of the reactor body 1. The discharge port 9 is connected to a delivery pipeline and... A fluoroplastic diaphragm pump 10 is connected to the feed inlet of the plate and frame filter press 4; an ammonia water inlet assembly is also provided at the bottom of the reactor body 1. The ammonia water inlet assembly includes an annular pipe 20 and multiple ammonia water injection pipes 21 evenly arranged in a clockwise direction inside the annular pipe 20. The multiple ammonia water injection pipes 21 are all horizontally arranged and have outlets at the top. Multiple support rods 22 fixed to the bottom of the reactor body 1 are provided at the bottom of the annular pipe 20. An inlet interface connected to the ammonia water inlet pipe 23 is also provided on the annular pipe 20. The ammonia water inlet pipe 23 passes through the reactor body 1 and is connected to the ammonia water storage tank 3 located on one side of it. An inlet valve and an ammonia water inlet pump 25 are provided on the ammonia water inlet pipe 23.

[0030] The horizontal reaction tank 31 includes vertical plates 34 on both side walls, an arc plate 35 at the bottom, a cover plate 36 at the top, and end caps 37 at both ends. The mixing mechanism includes a mixing motor a38 and a mixing motor b39 respectively mounted on the end caps 37 at both ends. The shafts of the mixing motors a38 and b39 are respectively connected to horizontal 316L stainless steel spiral shafts a40 and b41 located inside the horizontal reaction tank 31. The arc plate 35 has a cryolite suspension discharge port 42 with a discharge valve at the bottom center. The cover plate 36 has an ammonium fluoride solution inlet 50 and a outlet 50 in the middle. Air inlet 51; the liquid outlet of the plate and frame filter press 4 is connected to the ammonium fluoride solution inlet interface 50 through the ammonium fluoride solution inlet pipe; the aluminum hydroxide powder silo 32 and sodium hydroxide powder silo 33 are respectively located on both sides above the cover plate 36 at the top of the horizontal reaction tank 31. The bottom of the aluminum hydroxide powder silo 32 and the sodium hydroxide powder silo 33 are both conical structures, and the cone angle of the silo bottom is ≥70°. Vibration motors 44 are provided on both sides of the silo bottom. The conical surface of the silo bottom is lined with a 316L stainless steel polished plate. The discharge ports of the aluminum hydroxide powder silo 32 and the sodium hydroxide powder silo 33 are respectively connected to the aluminum hydroxide inlet interface and the sodium hydroxide inlet interface on the cover plate 36 through pneumatic butterfly valves and sealing flanges.

[0031] In another technical solution, the reactor body 1 is made of 316L stainless steel and lined with polytetrafluoroethylene. Multiple sensors are installed at different locations within the reactor body, including a temperature sensor (using a Pt100 resistance thermometer, accuracy ±0.5℃), a pH sensor (accuracy ±0.01), and a level sensor (using a magnetic level gauge, accuracy ±5mm). These sensors can monitor parameters such as temperature, pH, and level within the reactor in real time.

[0032] In another technical solution, there are six ammonia injection pipes 21, each with a diameter of 10-15 mm. If the diameter of the ammonia injection pipe is too small, it will easily become clogged; if the diameter is too large, the flow velocity will be too low to form turbulence.

[0033] In another technical solution, the exhaust gas conveying pipe is made of PP material, and the end of the exhaust gas conveying pipe 6 is connected to the inlet of the dilute sulfuric acid packed tower to avoid environmental pollution.

[0034] In another technical solution, the waste fluoride water delivery pipeline is equipped with a discharge valve, and the end of the ammonia water inlet pipe 23 is equipped with an inlet check valve.

[0035] In another technical solution, the outer wall of the reactor body 1 is also provided with a cooling water jacket 26 for cooling, so as to avoid the side reaction caused by excessive temperature.

[0036] In another technical solution, the horizontal reaction tank 31 is made of 316L stainless steel and lined with polytetrafluoroethylene.

[0037] In another technical solution, the bottom of the horizontal reaction tank 31 is provided with a support frame 43.

[0038] In another technical solution, horizontal 316L stainless steel spiral shafts a40 and b41 are located at the same height but rotate in opposite directions, and both are coated with a polytetrafluoroethylene layer. Horizontal 316L stainless steel spiral shaft a40 conveys the powder falling from aluminum hydroxide powder silo 32 towards the other end, while horizontal 316L stainless steel spiral shaft b41 conveys the returned material falling from sodium hydroxide powder silo 33 towards the aluminum hydroxide powder silo 32 end, forming a confluence and promoting the reaction.

[0039] In another technical solution, the exhaust port 51 is connected to an exhaust pipe, which is made of PP material and equipped with a wire mesh demister. The end of the exhaust pipe is connected to the air inlet of the dilute sulfuric acid packed tower.

[0040] In another technical solution, the top of the horizontal reaction tank 31 is also equipped with multiple 360° rotating spray balls for water spraying and cleaning. The spray balls are made of PTFE. The water inlet pipes of the spray balls are connected to an external water source, and the horizontal reaction tank is cleaned by connecting to an external water source when cleaning is required.

[0041] In another technical solution, the horizontal reaction tank 31 is wrapped with heat-conducting oil jackets 52 on both sides and the bottom to maintain the reaction temperature at 80-90℃ and promote the reaction.

[0042] Working principle: Waste fluoride from the phosphate fertilizer industry (containing approximately 12% fluorosilicic acid) in the waste fluoride storage tank is added to the reactor through the waste fluoride inlet and the waste fluoride delivery pipeline. Then, the stirring motor is started. Ammonia from the ammonia storage tank is added to the reactor through the ammonia inlet pipe and multiple ammonia injection pipes of the ammonia inlet assembly to react with the fluorosilicic acid. The temperature of the reactor is controlled, and ammonia is added gradually. The pH is controlled at 8.5-9. Ammoniation takes 1-1.2 hours. To avoid ammonia volatilization, the reaction temperature is preferably 35-40℃. An ammonolysis mixture is obtained. The ammonolysis mixture is connected to a plate and frame filter press through the outlet, the delivery pipeline, and the fluoroplastic diaphragm pump. The filtrate is an ammonium fluoride solution. The outlet of the plate and frame filter press is connected to the ammonium fluoride solution inlet pipe and the ammonium fluoride solution inlet interface to deliver ammonium fluoride solution into the horizontal reaction tank. Then, aluminum hydroxide powder and sodium hydroxide powder are added in proportion. The mixing motors a and b are started to drive the horizontal 316L stainless steel spiral shafts a and b41 to dissolve and stir the mixed solution. The temperature in the horizontal reaction tank is controlled at 80-90℃ by heating with a heat transfer oil jacket. After the reaction is complete, cryolite suspension is generated and finally discharged from the cryolite suspension discharge port for further processing.

[0043] The above-described embodiments are only intended to illustrate the technical solution and features of this utility model, and are intended to enable those skilled in the art to implement them. They should not be used to limit the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model are within the scope of protection of this utility model. Anything not described in detail is prior art.

Claims

1. A reaction apparatus for preparing cryolite suspension using fluoride wastewater, comprising an ammonium fluoride production unit and a cryolite suspension production unit, wherein the ammonium fluoride production unit includes a reaction vessel (1), a waste fluoride water storage tank (2), an ammonia water storage tank (3), and a plate and frame filter press (4), and the cryolite suspension production unit includes a horizontal reaction tank (31), an aluminum hydroxide powder silo (32), a sodium hydroxide powder silo (33), and a stirring and mixing mechanism, characterized in that, The reactor body (1) has a waste fluoride water inlet (5) on one side of its top, which is connected to the bottom of the waste fluoride water storage tank (2) through a waste fluoride water delivery pipeline. A stirring motor (11) is located at the center of the top of the reactor body (1). The rotating shaft of the stirring motor (11) is connected to a stirring shaft (12) that extends into the reactor body (1). A stirring paddle assembly is provided on the stirring shaft (12). The other side of the top of the reactor body (1) has a tail gas outlet, which is connected to a tail gas delivery pipeline (6). A gas-liquid separator (7) and a tail gas delivery fan (8) are sequentially provided on the tail gas delivery pipeline (6). The bottom of the reactor body (1) has a conical structure. The bottom end of the reactor body (1) has a discharge port (9) with a discharge valve. The discharge port (9) is connected to the delivery pipeline. The fluoroplastic diaphragm pump (10) is connected to the feed port of the plate and frame filter press (4); the bottom of the reactor body (1) is also provided with an ammonia water inlet assembly, which includes an annular pipe (20) and multiple ammonia water injection pipes (21) evenly arranged in a clockwise direction inside the annular pipe (20). The multiple ammonia water injection pipes (21) are all horizontally arranged and have outlets at the top. The lower part of the annular pipe (20) is provided with multiple support rods (22) fixed to the bottom of the reactor body (1). The annular pipe (20) is also provided with an inlet interface connected to the ammonia water inlet pipe (23). The ammonia water inlet pipe (23) passes through the reactor body (1) and is connected to the ammonia water storage tank (3) located on one side of it. The ammonia water inlet pipe (23) is provided with an inlet valve and an ammonia water inlet pump (25). The horizontal reaction tank (31) includes vertical plates (34) on both side walls, an arc plate (35) at the bottom, a cover plate (36) at the top, and end caps (37) at both ends. The stirring and mixing mechanism includes a mixing motor a (38) and a mixing motor b (39) respectively installed on the end caps (37) at both ends. The rotating shafts of the mixing motor a (38) and the mixing motor b (39) are respectively connected to a horizontal 316L stainless steel spiral shaft a (40) and a horizontal 316L stainless steel spiral shaft b (41) installed in the horizontal reaction tank (31). The arc plate (35) has a cryolite suspension discharge port (42) with a discharge valve at the bottom center. The cover plate (36) has an ammonium fluoride solution inlet port (5) in the middle. 0) and exhaust port (51), the liquid outlet of the plate and frame filter press (4) is connected to the ammonium fluoride solution inlet port (50) through the ammonium fluoride solution inlet pipe; the aluminum hydroxide powder silo (32) and sodium hydroxide powder silo (33) are located on both sides above the cover plate (36) at the top of the horizontal reaction tank (31), the bottom of the aluminum hydroxide powder silo (32) and the sodium hydroxide powder silo (33) are both conical structures, and the cone angle of the bottom of the silo is ≥70°. Vibration motors (44) are provided on both sides of the bottom of the silo. The cone surface of the bottom of the silo is lined with 316L stainless steel polished plate. The discharge ports of the aluminum hydroxide powder silo (32) and the sodium hydroxide powder silo (33) are connected to the aluminum hydroxide inlet port and the sodium hydroxide inlet port on the cover plate (36) through the pneumatic butterfly valve and the sealing flange, respectively.

2. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The reactor body (1) is made of 316L stainless steel and lined with polytetrafluoroethylene.

3. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The number of ammonia injection pipes (21) is six, and the diameter of the ammonia injection pipes (21) is 10-15 mm.

4. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The exhaust gas conveying pipe is made of PP material, and the end of the exhaust gas conveying pipe (6) is connected to the inlet of the dilute sulfuric acid packed tower.

5. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The waste fluoride water delivery pipeline is equipped with a discharge valve, and the end of the ammonia water inlet pipe (23) is equipped with an inlet check valve.

6. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The outer wall of the reactor body (1) is also provided with a cooling water jacket (26) for cooling.

7. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The horizontal reaction tank (31) is made of 316L stainless steel and lined with polytetrafluoroethylene. A support frame (43) is provided at the bottom of the horizontal reaction tank (31).

8. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The horizontal 316L stainless steel spiral shaft a (40) and the horizontal 316L stainless steel spiral shaft b (41) are located at the same height and are arranged in opposite directions of rotation, and both of their surfaces are covered with a polytetrafluoroethylene layer.

9. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The exhaust port (51) is connected to the exhaust pipe, which is made of PP material and equipped with a wire mesh demister. The end of the exhaust pipe is connected to the air inlet of the dilute sulfuric acid packed tower.

10. The reaction apparatus for preparing cryolite suspension using fluoride wastewater according to claim 1, characterized in that, The horizontal reaction tank (31) is covered with heat transfer oil jackets (52) on both sides and at the bottom.

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