A kind of salt water pretreatment device and treatment method for aluminum removal

Abstract

A device and method for pre-treating desalinated water for aluminum removal, comprising a mixing tank, a desalinated water injection pipe assembly, a hydrochloric acid injection mechanism, and a control device. The hydrochloric acid injection mechanism comprises a rotating shaft, a hydrochloric acid input pipe assembly, and a mixing blade. The rotating shaft comprises a through slot. The hydrochloric acid input pipe assembly comprises a control valve. The mixing blade comprises a main body, a first connecting slot, a second connecting slot, and a spray hole. The first and second connecting slots and the spray hole are respectively arranged on three adjacent side walls of the main body. The control module comprises positive and negative electrode plates, and a control unit. The control unit converts the voltage value into a pH value and controls the opening and closing of the control valve according to the pH value. The desalinated water pre-treating device for aluminum removal can realize automatic control, save operation time, and reduce the labor intensity of staff.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical industry, and in particular to a device and method for pretreating light brine for removing aluminum. Background Art

[0002] In the prior art, membrane filters are commonly used to filter some chemical liquids to remove impurities, allowing for the recycling of either the filtered liquid or the filtered residue, or both. Chemical liquids containing aluminum salts are difficult to remove due to the high aluminum content (typically around 500 ppb) in the brine exiting the ion-exchange membrane cell, with a pH typically controlled at around 10. However, due to the acidic and alkaline properties of aluminum, when the pH of the brine is controlled to 5 to 6, the aluminum is converted to Al(OH)3, which is insoluble or slightly soluble in water and can be removed by filtration. Conventional membrane filters consist of a membrane filter assembly, a manual control valve, a pneumatic control valve, a liquid feed pump, an acid wash pump, an outlet pressure gauge, and an automatic control box. The entire control process is divided into four parts: filtration, backwashing, acid washing, and displacement. Filtration involves a control system activating the liquid feed pump to introduce brine through the liquid feed passage into the membrane filter assembly. After filtration, the clear liquid exits the system, leaving trapped matter attached to the membrane surface. Backwashing involves manually setting a filtration time based on the filtration conditions. The filter automatically stops filtering after reaching the filtration time. After the backwash circuit is activated, the filtered clear fluid is used to backwash the membrane assembly, stripping away attached retained matter and settling it in the membrane assembly cavity. The clear fluid is then discharged through a drain line into the slag pool, restoring the membrane assembly's filtration capacity. Acid washing involves cleaning the membrane assembly with hydrochloric acid if scale still forms on its surface after a period of filtration and backwashing. The control system introduces hydrochloric acid into the membrane assembly via an acid pump, restoring the membrane assembly's performance through hydrochloric acid aeration and other methods. Finally, replacement is performed. After the acid wash is complete, the control system automatically replaces the membrane assembly with filtered brine. Once the acid wash solution is replaced, the system automatically enters filtration mode. Therefore, regulating the pH value of the brine is crucial to the long-term safe and stable operation of the membrane filter. Summary of the Invention

[0003] In view of this, the present invention provides a brine pretreatment device and treatment method for removing aluminum to meet the above needs.

[0004] A device for pre-treating dilute brine for aluminum removal, wherein the dilute brine contains aluminum and has a pH greater than 7. The device comprises a mixing tank, a dilute brine injection pipe assembly disposed on the mixing tank, a hydrochloric acid injection mechanism disposed on the mixing tank, and a control device disposed on the mixing tank. The dilute brine injection pipe assembly is used to inject the dilute brine into the mixing tank. The hydrochloric acid injection mechanism comprises a rotating shaft disposed axially along the mixing tank, a hydrochloric acid inlet pipe assembly connected to the rotating shaft and disposed on the outside of the mixing tank, and at least one mixing blade disposed on a sidewall of the rotating shaft. The rotating shaft is a hollow tube and includes at least one through-slot. The hydrochloric acid inlet pipe assembly includes a control valve. The mixing blade is secured in the through-slot and comprises a body, a first connecting slot disposed on a sidewall of the body, a second connecting slot disposed on a sidewall of the body, and a plurality of spray holes disposed on a sidewall of the body. The first and second connecting slots and the spray holes are respectively arranged on three adjacent side walls of the main body, and the spray holes and the first connecting slot are arranged on two opposite side walls. The second connecting slot is arranged toward the hydrochloric acid inlet pipe assembly. The rotating shaft drives the mixing blade to rotate. The control module includes positive and negative electrode plates arranged at intervals on the inner wall of the mixing tank, and a control unit electrically connected to the positive and negative electrode plates. The positive and negative electrode plates are used to detect the voltage value in the liquid in the mixing tank. The control unit converts the voltage value into a pH value and controls the opening and closing of the control valve according to the size of the pH value. When the voltage value is converted into a pH value and the pH value is greater than 6, the control unit controls the control valve to open, and when the pH value is less than 6, the control unit controls the control valve to close.

[0005] Furthermore, the salt water injection pipe assembly includes an injection pipe arranged on the side wall of the mixing tank, and a first switch valve arranged on the injection pipe.

[0006] Furthermore, the central axis of the rotating shaft coincides with the central axis of the mixing tank.

[0007] Furthermore, the hydrochloric acid input pipe assembly includes an input pipe fixed to the mixing tank, and the control valve is arranged on the input pipe to control the on-off of the input pipe.

[0008] Furthermore, the hydrochloric acid injection mechanism also includes a partition arranged in the mixing tank, and a driving mechanism arranged on the partition, the driving mechanism and the rotating shaft are respectively arranged on both sides of the partition and drive the rotating shaft to rotate, and the rotating shaft is arranged between the partition and the top of the mixing tank.

[0009] Furthermore, the rotating shaft and the partition are sealed.

[0010] Furthermore, the desalinated brine pretreatment device for aluminum removal also includes a discharge pipe assembly arranged on the side wall of the mixing tank, the discharge pipe assembly includes a discharge pipe arranged on the side wall of the mixing tank, and a second switch valve arranged on the discharge pipe, the discharge pipe is arranged below the input pipe and above the partition.

[0011] Furthermore, the device for pre-treating the desalinated water for removing aluminum further comprises a pre-treatment tank for receiving the desalinated water from the discharge pipe.

[0012] A method for pretreating light brine for removing aluminum comprises the following steps:

[0013] STEP 101: Provide the above-mentioned salt water pretreatment device for aluminum removal, and inject salt water into the mixing tank through the salt water injection pipe assembly;

[0014] STEP 102: The positive and negative electrode plates measure the voltage of the liquid in the mixing tank, and the control unit converts the voltage into a pH value;

[0015] STEP 103: When the pH value is greater than 6, the control unit controls the rotating shaft to start rotating;

[0016] STEP 104: When the pH value is greater than 6, the control unit controls the control valve to open to inject hydrochloric acid into the mixing tank and reduce the pH value in the mixing tank to 5-6;

[0017] STEP 105: When the pH value drops to 5-6, close the control valve and stop injecting hydrochloric acid into the mixing tank.

[0018] Furthermore, the brine pretreatment device for aluminum removal also includes a discharge pipe assembly arranged on the side wall of the mixing tank, the discharge pipe assembly includes a discharge pipe arranged on the side wall of the mixing tank, a second switch valve arranged on the discharge pipe, and a pretreatment tank for receiving brine from the discharge pipe. When the injection of brine into the mixing tank is stopped, the second switch valve is opened to allow the acid-treated liquid to flow into the pretreatment tank and the liquid is pumped into the filter by a pump for filtration.

[0019] Compared with the prior art, the salt water pretreatment device for aluminum removal provided by the present invention is provided with the hydrochloric acid injection mechanism in the mixing tank, a first switch valve is provided on the injection pipe, and a second switch valve is provided on the discharge pipe. At the same time, the control module includes positive and negative electrode plates provided in the mixing tank, so that the control valve and the opening and closing of the first and second switch valves can be controlled by detecting the voltage value in the mixing tank, thereby achieving automated control, saving operation time, reducing the labor intensity of staff, and reducing production and operation costs to a certain extent. In particular, through the structural design of the mixing blades in the hydrochloric acid injection mechanism, the salt water and hydrochloric acid can be fully mixed to shorten the mixing time, further improve production efficiency, and save time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a structural schematic diagram of a desalinated water pretreatment device for aluminum removal provided by the present invention.

[0021] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of a mixing tank of a brine pretreatment device for aluminum removal.

[0022] Figure 3 for Figure 1 Schematic diagram of the structure of the mixing blades of the desalinated water pretreatment device for removing aluminum.

[0023] Figure 4 for Figure 1 A schematic structural diagram of the mixing blades of the desalinated brine pretreatment device for removing aluminum from another angle.

[0024] Figure 5 for Figure 1 Schematic diagram of the structure of the rotating shaft of the desalinated water pretreatment device for removing aluminum. DETAILED DESCRIPTION

[0025] The following is a further detailed description of specific embodiments of the present invention. It should be understood that the description of the embodiments of the present invention herein is not intended to limit the scope of protection of the present invention.

[0026] like Figures 1 to 5As shown, it is a structural schematic diagram of the desalted water pretreatment device for aluminum removal provided by the present invention. The desalted water pretreatment device for aluminum removal is used to pretreat desalted water. The desalted water contains aluminum, and the pH value of the desalted water is greater than 7. The desalted water pretreatment device for aluminum removal includes a mixing tank 10, a desalted water injection pipe assembly 20 arranged on the mixing tank 10, a hydrochloric acid injection mechanism 30 arranged on the mixing tank 10, a discharge pipe assembly 40 arranged on the side wall of the mixing tank, and a control device 50 arranged on the mixing tank 10. It can be understood that the desalted water pretreatment device for aluminum removal also includes some other functional modules, such as assembly components, installation components, electrical connection components, etc., which are technologies well known to those skilled in the art and will not be repeated here.

[0027] The mixing tank 10 can be a reactor, which is arranged on a base. The mixing tank 10 can be a sealed tank body with an opening for installing various components and functional modules, such as the salt water injection pipe assembly 20, the hydrochloric acid injection mechanism 30, etc.

[0028] The dilute brine injection pipe assembly 20 includes an injection pipe 21 provided on the side wall of the mixing tank 10, and a first switch valve 22 provided on the injection pipe 21. The injection pipe 21 is used to inject the dilute brine into the mixing tank 10. The first switch valve 22 can be a manual control valve or a solenoid valve, which is used to control the opening and closing of the injection pipe 21. When the dilute brine needs to be pretreated, the first switch valve 22 can be opened manually or by the control device 50 to allow the dilute brine to be injected into the mixing tank 10, and the first switch valve 22 can be opened and closed when the injection amount reaches the requirement.

[0029] The hydrochloric acid injection mechanism 30 includes a partition 31 fixedly disposed within the mixing tank 10, a rotating shaft 32 disposed axially of the mixing tank 10 and between the partition 31 and the top of the mixing tank 10, a hydrochloric acid inlet pipe assembly 33 connected to the rotating shaft 32 and disposed outside the mixing tank 10, at least one mixing blade 34 disposed on the sidewall of the rotating shaft 32, and a drive mechanism 35 disposed on the partition 31. The partition 31 is disposed radially of the mixing tank 10, and the mixing tanks 10 are sealed from each other. The central axis of the rotating shaft 32 can coincide with the central axis of the mixing tank 10. However, if the mixing blade 34 is not too large, the rotating shaft 32 and the central axis of the mixing tank 10 may not coincide, i.e., be eccentric. However, the central axis of the rotating shaft 32 should be parallel to the central axis of the mixing tank 10. The rotating shaft 32 is a hollow tube and includes at least one through-slot 321. The hollow nature of the rotating shaft 32 facilitates the inlet of hydrochloric acid. The through slot 321 is used to insert and install the mixing blade 34, so its size should be comparable to the size of the mixing blade 34. One end of the rotating shaft 32 is located on the partition 31, and the other end is located at the top of the mixing tank 10. Therefore, to ensure smooth rotation of the rotating shaft 32, the rotating shaft 32 is connected to the partition 31 and the top of the mixing tank 10 via a bearing. It is conceivable that the connection between the bearing, the partition 31 and the top of the mixing tank 10 should be sealed to prevent liquid from leaking. The hydrochloric acid inlet pipe assembly 32 is located at the top of the mixing tank 10 and connected to the rotating shaft 32 to feed hydrochloric acid into the rotating shaft 32 and thus into the mixing tank 10. The hydrochloric acid inlet pipe assembly 33 includes an inlet pipe 331 sealed with the rotating shaft 32 and a control valve 332 located on the inlet pipe 331. The control valve 332 can be a solenoid valve that can be opened or closed by a control signal. There can be one or more mixing blades 34; in this embodiment, there are two mixing blades 34. The two mixing blades 34 are symmetrically arranged on the rotating shaft 32, with their arrangement symmetrically about the central axis of the rotating shaft 32. Each mixing blade 34 is fixed in the through-slot 321 and includes a body 341, a first connecting slot 342 provided on a sidewall of the body 341, a second connecting slot 343 provided on a sidewall of the body 341, and a plurality of spray holes 344 provided on a sidewall of the body 341. The body 341 is a plate-like structure. The first connecting slot 342 communicates with the through-slot 321 to receive hydrochloric acid from the rotating shaft 32.The first and second connecting slots 342, 343, and the spray hole 344 are respectively disposed on three adjacent sidewalls of the body 341, with the spray hole 344 and the first connecting slot 342 disposed on two opposing sidewalls. The first and second connecting slots 342, 343, and the spray hole 344 are interconnected. When hydrochloric acid is injected into the rotating shaft 32 from the hydrochloric acid inlet pipe assembly 33, the hydrochloric acid flows from the through-slot 321 into the first connecting slot 342 and then into the spray hole 344. As the rotating shaft 32 rotates, the liquid in the mixing blades 34 is rapidly ejected from the spray hole 344 under the action of centrifugal force, creating a negative pressure within the mixing blades 34. Consequently, the liquid in the mixing tank 10 is forced into the mixing blades 34 through the second connecting slot 342 and ejected through the spray hole 13 along with the poor hydrochloric acid, effectively improving the mixing efficiency of the hydrochloric acid and the dilute brine per unit time. Of course, it is conceivable that the mixing blades 34 can also play a stirring role during their rotation, thereby achieving the purpose of mixing. The drive mechanism 35 includes a drive motor 351. In order to reduce the size of the mixing tank 10 and improve the mixing effect, the drive mechanism 35 also includes two bevel gears meshing at 90 degrees to each other, one of which is connected to the rotating shaft 32, thereby driving the rotating shaft 32 to rotate.

[0030] The discharge pipe assembly 40 includes a discharge pipe 41 disposed on the side wall of the mixing tank 10, a second on-off valve 42 disposed on the discharge pipe 41, and a pre-treatment tank 43 for receiving the treated liquid from the discharge pipe 41. The discharge pipe 41 is disposed below the injection pipe 31 and above the partition 31. It is conceivable that in order to control the opening and closing of the discharge pipe 41, the second on-off valve 42 is disposed on the discharge pipe 41, which can also be a solenoid valve. After the pre-treatment tank 43 receives the pre-treated liquid, it is pumped into the filter by a liquid pump for filtration.

[0031] The control device 50 includes positive and negative electrode plates 51 and 52 spaced apart on the inner wall of the mixing tank 10, a high-sensitivity voltmeter 53 electrically connected to the positive and negative electrode plates 51 and 52, and a control unit 54 electrically connected to the high-sensitivity voltmeter 23. The positive and negative electrode plates 51 and 52 are used to detect the instantaneous voltage in the mixing tank 10. The working principle thereof should be the existing technology and will not be described here. The high-sensitivity voltmeter 53 is used to obtain the voltage value from the positive and negative electrode plates 51 and 52. The control unit 54 includes a processor and a PLC controller. The processor is used to process the voltage value transmitted from the high-sensitivity voltmeter 53. Specifically, the processor converts the voltage value into a pH value. The pH value can be used to know the pH value in the mixing tank 10, so that the injection amount of hydrochloric acid can be controlled, that is, the processor controls the opening and closing of the control valve 332 according to the pH value. Specifically, when the voltage value is converted to a pH value greater than 6, the control unit 54 controls the control valve 332 to open to inject hydrochloric acid. As the hydrochloric acid continues to be injected, when the pH value drops below 6, specifically, when the pH value is between 5 and 6, the control unit 54 controls the control valve 332 to close, indicating that the pretreatment of the dilute brine is complete and the next step can be performed. Aluminum hydroxide is an amphoteric hydroxide. Because it exists in two ionized forms—a weak acid with the acidic chemical formula H3AlO3 and a weak base with the basic chemical formula Al(OH)3—aluminum hydroxide is amphoteric, reacting with both acids and bases. However, at a pH between 5 and 6, aluminum hydroxide does not dissolve. Therefore, at this pH, it can be processed by filtration. The PLC controller itself is conventional technology and will not be described in detail here. It is used to control the opening and closing of the control valve 332 and the first and second on-off valves 22 and 42 based on control information from the processor.

[0032] The present invention also provides a method for pretreating light brine for removing aluminum, which comprises the following steps:

[0033] STEP 101: Provide the above-mentioned salt water pretreatment device for aluminum removal, and inject salt water into the mixing tank 10 through the salt water injection pipe assembly 20;

[0034] STEP 102: The positive and negative electrode plates 51 and 52 measure the voltage of the liquid in the mixing tank 10, and the control unit 54 converts the voltage into a pH value.

[0035] STEP 103: When the pH value is greater than 6, the control unit 54 controls the rotating shaft 32 to start rotating;

[0036] STEP 104: When the pH value is greater than 6, the control unit 54 controls the control valve 332 to open to inject hydrochloric acid into the mixing tank 10 until the pH value in the mixing tank 10 drops to 5-6;

[0037] STEP 105: When the pH value drops to 5-6, close the control valve 332 and stop injecting hydrochloric acid into the mixing tank.

[0038] STEP 106: Open the second on-off valve 42 to allow the acid-treated liquid to flow into the pretreatment tank 43 and pump the liquid into the filter through a pump for filtration.

[0039] Compared with the prior art, the desalted brine pretreatment device for aluminum removal provided by the present invention is provided with the hydrochloric acid injection mechanism 30 in the mixing tank, and a first switch valve 22 is provided on the injection pipe 20, and a second switch valve 42 is provided on the discharge pipe 42. At the same time, the control module 50 includes positive and negative electrode plates 51 and 52 provided on the mixing tank 10, so that the control valve 332 and the first and second switch valves 22 and 42 can be controlled by detecting the voltage value in the mixing tank 10, thereby achieving automated control, saving operation time, reducing the labor intensity of the staff, and reducing the production and operation costs to a certain extent. In particular, through the structural design of the mixing blades 34 in the hydrochloric acid injection mechanism 30, the desalted brine and hydrochloric acid can be fully mixed to shorten the mixing time, further improve production efficiency, and save time.

[0040] The above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements or improvements within the spirit of the present invention are included in the scope of the claims of the present invention.

Claims

1. A device for pretreating light brine for removing aluminum, wherein the light brine contains aluminum and has a pH value greater than 7, characterized in that: The brine pretreatment device for aluminum removal includes a mixing tank, a brine injection pipe assembly arranged on the mixing tank, a hydrochloric acid injection mechanism arranged on the mixing tank, and a control device arranged on the mixing tank. The brine injection pipe assembly is used to inject the brine into the mixing tank. The hydrochloric acid injection mechanism includes a rotating shaft arranged along the axial direction of the mixing tank, a hydrochloric acid input pipe assembly connected to the rotating shaft and arranged on the outside of the mixing tank, and at least one mixing blade arranged on the side wall of the rotating shaft. The rotating shaft is a hollow tube and includes at least one through groove. The hydrochloric acid input pipe assembly includes a control valve. The mixing blade is fixed in the through groove and includes a body, a first connecting slot hole arranged on a side wall of the body, a second connecting slot hole arranged on a side wall of the body, and a plurality of spray holes arranged on a side wall of the body, the first connecting slot hole is connected to the through slot, the first and second connecting slot holes and the spray hole are respectively arranged on three adjacent side walls of the body, and the spray hole and the first connecting slot hole are arranged on two opposite sides. On the wall, the second communicating slot is arranged toward the hydrochloric acid input pipe assembly, the first and second communicating slots and the spray hole are connected to each other, the rotating shaft drives the mixing blade to rotate, when hydrochloric acid is injected into the rotating shaft from the hydrochloric acid input pipe assembly, the hydrochloric acid will flow from the through slot into the first communicating slot, and then into the spray hole. When the rotating shaft rotates, the liquid in the mixing blade will be quickly ejected from the spray hole under the action of centrifugal force, thereby forming a negative pressure inside the mixing blade, and then the liquid in the mixing tank will be pressed into the mixing blade from the second communicating slot, accompanied by As hydrochloric acid is sprayed out through the nozzle, the control device includes positive and negative electrode plates spaced apart on the inner wall of the mixing tank, and a control unit electrically connected to the positive and negative electrode plates. The positive and negative electrode plates are used to detect the voltage value in the liquid in the mixing tank. The control unit converts the voltage value into a pH value and controls the opening and closing of the control valve according to the pH value. When the voltage value is converted into a pH value and the pH value is greater than 6, the control unit controls the control valve to open, and when the pH value is less than 6, the control unit controls the control valve to close.

2. The device for pretreating light salt water for aluminum removal according to claim 1, wherein: The salt water injection pipe assembly includes an injection pipe arranged on the side wall of the mixing tank and a first switch valve arranged on the injection pipe.

3. The device for pretreating light salt water for aluminum removal according to claim 1, wherein: The central axis of the rotating shaft coincides with the central axis of the mixing tank.

4. The device for pretreating light salt water for aluminum removal according to claim 1, wherein: The hydrochloric acid input pipe assembly includes an input pipe fixed to the mixing tank, and the control valve is arranged on the input pipe to control the on-off of the input pipe.

5. The device for pretreating light salt water for removing aluminum according to claim 4, characterized in that: The hydrochloric acid injection mechanism also includes a partition arranged in the mixing tank, and a driving mechanism arranged on the partition, the driving mechanism and the rotating shaft are respectively arranged on both sides of the partition, the driving mechanism drives the rotating shaft to rotate, and the rotating shaft is arranged between the partition and the top of the mixing tank.

6. The device for pretreating light salt water for aluminum removal according to claim 5, characterized in that: The rotating shaft and the partition are sealed.

7. The device for pretreating light salt water for aluminum removal according to claim 5, characterized in that: The desalinated brine pretreatment device for aluminum removal also includes a discharge pipe assembly arranged on the side wall of the mixing tank, the discharge pipe assembly includes a discharge pipe arranged on the side wall of the mixing tank, and a second switch valve arranged on the discharge pipe, the discharge pipe is arranged below the input pipe and above the partition.

8. The device for pretreating light salt water for aluminum removal according to claim 7, characterized in that: The device for pre-treating the light brine for removing aluminum further comprises a pre-treatment tank for receiving the treated liquid from the discharge pipe.

9. A method for pretreating light brine for aluminum removal, comprising the following steps: STEP 101: Provide the brine pretreatment device for aluminum removal according to any one of claims 1 to 7, and inject brine into the mixing tank through the brine injection pipe assembly; STEP 102: Measuring the voltage of the liquid in the mixing tank by the positive and negative electrode plates, and converting the voltage into a pH value by a control unit; STEP 103: When the pH value is greater than 6, the control unit controls the rotating shaft to start rotating; STEP 104: When the pH value is greater than 6, the control unit controls the control valve to open to inject hydrochloric acid into the mixing tank and reduce the pH value in the mixing tank to 5-6; STEP 105: When the pH value drops to 5-6, close the control valve and stop injecting hydrochloric acid into the mixing tank.

10. The method for pretreating light salt water for aluminum removal according to claim 9, wherein: The brine pretreatment device for aluminum removal also includes a discharge pipe assembly arranged on the side wall of the mixing tank, the discharge pipe assembly includes a discharge pipe arranged on the side wall of the mixing tank, a second switch valve arranged on the discharge pipe, and a pretreatment tank for receiving treated liquid from the discharge pipe. When the injection of brine into the mixing tank is stopped, the second switch valve is opened to allow the acid-treated liquid to flow into the pretreatment tank and the liquid is pumped into the filter by a pump for filtration.

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