Filter cloth anti-blocking system of aluminum ash treatment vacuum belt filter

Abstract

The utility model relates to a filter cloth anti-blocking system of a vacuum belt filter for aluminum ash treatment. The filter cloth anti-blocking system comprises a raw material slurry supply pipeline, a sodium hydroxide solution storage tank, a plurality of reaction tanks, the vacuum belt filter, a plurality of strong brine sedimentation tanks, an MVR (mechanical vapor recompression) evaporator, a sedimentation slurry stirring tank and a carbon dioxide preparation device, the raw material slurry supply pipeline is communicated with a sodium hydroxide solution storage tank, the tail end of the raw material slurry supply pipeline is communicated with the first reaction tank, the plurality of reaction tanks are sequentially communicated in series, and the last reaction tank is communicated with the liquid inlet end of the vacuum belt filter; the liquid outlet end of the vacuum belt filter is connected with a plurality of strong brine depositing tanks in parallel, and the strong brine depositing tanks are communicated with the MVR evaporator; the strong brine settling tank is communicated with an inlet of the settling slurry stirring tank; an outlet of the settling slurry stirring tank is communicated with the vacuum belt filter; the strong brine settling tank is communicated with the carbon dioxide preparation device. The sodium hydroxide solution is introduced into the slurry, and aluminum hydroxide colloid is not generated after the sodium hydroxide solution and the slurry react, so that the filter cloth is prevented from being blocked.

Description

Technical Field

[0001] The utility model relates to the technical field of aluminum ash processing, in particular to an anti-clogging system for filter cloth of a vacuum belt filter for aluminum ash processing. Background Art

[0002] Hydrolysis can be used to dispose of salt slag aluminum ash in harmless treatment and high-value applications. Salt slag aluminum ash reacts with water, hydrolyzing the aluminum nitride and metallic aluminum in the ash to produce a large amount of aluminum hydroxide colloid in the slurry. When the slurry passes through the subsequent vacuum belt filter for solid-liquid separation, the aluminum hydroxide colloid in the slurry can clog the filter cloth, losing its filtration performance. Consequently, the liquid in the slurry cannot be filtered smoothly into the liquid receiving tank below the filter cloth. Ultimately, after slurry filtration, the filter cake on the vacuum belt filter has the following disadvantages: 1. The liquid is salty and difficult to pass through the filter cloth. As a result, the inert aluminum oxide produced after the filter cake is dried has a high salt content, resulting in an unqualified product. 2. The filter cake has a high moisture content, resulting in excessive drying energy consumption and increased production costs. 3. The high moisture content of the filter cake makes it prone to adhering to the pipe wall during transfer to the dryer, clogging the dryer feed port, causing production interruptions and reducing production efficiency. Summary of the Invention

[0003] In order to solve the problem that aluminum hydroxide colloid generated when salt slag aluminum ash is treated by a hydrolysis method is easy to clog the filter, the utility model provides an aluminum ash treatment vacuum belt filter cloth anti-clogging system, adopts a sodium hydroxide solution to pass into the slurry, and after the reaction between the two, no aluminum hydroxide colloid is generated, but sodium metaaluminate is generated and dissolved in the slurry, which can prevent the aluminum hydroxide colloid in the slurry from clogging the filter cloth.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0005] Aluminum ash treatment vacuum belt filter cloth anti-clogging system, including raw material slurry supply pipeline, sodium hydroxide solution storage tank, multiple reaction tanks, vacuum belt filter, multiple brine precipitation tanks, MVR evaporator, precipitation slurry stirring tank and carbon dioxide production device;

[0006] The raw material slurry supply pipeline is connected to the sodium hydroxide solution storage tank, which is convenient for introducing the sodium hydroxide solution into the slurry. The tail end of the raw material slurry supply pipeline is connected to the first reaction tank. The multiple reaction tanks are connected in series in sequence. The slurry flows through the multiple reaction tanks in sequence. The last reaction tank is connected to the liquid inlet end of the vacuum belt filter, which is convenient for passing the slurry into the filter.

[0007] The liquid outlet of the vacuum belt filter is connected in parallel with multiple concentrated brine precipitation tanks, which are connected to the MVR evaporator; the concentrated brine precipitation tank is connected to the inlet of the precipitation slurry stirring tank, and the outlet of the precipitation slurry stirring tank is connected to the vacuum belt filter, which is convenient for returning the slurry after sedimentation and aging to the filter; the bottom of the concentrated brine precipitation tank is connected to the carbon dioxide preparation device, which is convenient for the introduction of carbon dioxide gas.

[0008] Furthermore, a flow meter is provided on the raw material slurry supply pipeline to facilitate monitoring of the flow rate. The concentration of the sodium hydroxide solution in the sodium hydroxide solution storage tank is 25%. A solution delivery pipe is provided between the sodium hydroxide solution storage tank and the raw material slurry supply pipeline to communicate with each other. A metering pump is provided on the solution delivery pipe to facilitate pumping the sodium hydroxide solution and monitoring the flow rate at the same time.

[0009] Furthermore, a connecting pipe is provided between two adjacent reaction tanks to connect them, with one end of the connecting pipe connected to the bottom of the preceding reaction tank and the other end connected to the top of the following reaction tank. A connecting pipe is also provided between the bottom of the last reaction tank and the liquid inlet of the vacuum belt filter, and a slurry delivery pump is installed on the connecting pipe to facilitate the flow of slurry between the reaction tanks and to deliver the slurry to the filter.

[0010] Furthermore, the liquid outlet end of the vacuum belt filter is connected to a liquid outlet pipe, the liquid outlet pipe is connected in parallel to a plurality of the concentrated brine precipitation tanks, and a liquid outlet valve is provided between the liquid outlet pipe and each concentrated brine precipitation tank;

[0011] The MVR evaporator is connected to a pure brine pipe with a pure brine pump, the pure brine pipe is connected in parallel to multiple concentrated brine precipitation tanks, the pure brine pipe is connected to the side wall of the concentrated brine precipitation tank, and a pure brine valve is provided between the pure brine pipe and each concentrated brine precipitation tank.

[0012] Furthermore, the inlet of the precipitation slurry stirring tank is connected to a feed pipe, the feed pipe is connected in parallel to the bottom of multiple concentrated brine precipitation tanks, and a feed valve is provided between the feed pipe and each concentrated brine precipitation tank;

[0013] The outlet of the precipitation slurry stirring tank is connected to a discharge pipe, which is connected to a vacuum belt filter. Both the discharge pipe and the feed pipe are provided with precipitation slurry pumps, and the feed pipe is also provided with a main feed valve.

[0014] Furthermore, the carbon dioxide preparation device includes a carbon dioxide compressor and a carbon dioxide storage tank, a three-way pipe is connected between the carbon dioxide compressor and the carbon dioxide storage tank, a branch of the three-way pipe is connected in parallel with the bottom of multiple brine precipitation tanks, and an air supply valve is provided between one branch of the three-way pipe and each brine precipitation tank.

[0015] Through the above technical solution, the beneficial effects of the utility model are:

[0016] The utility model is equipped with a 25% sodium hydroxide solution storage tank, which can be used to add sodium hydroxide solution to the raw material slurry. Through the flow meter combined with the monitoring data of the metering pump, the sodium hydroxide content in the slurry can be controlled to 2%. At this time, the sodium hydroxide reacts with the harmful substances such as aluminum nitride, metallic aluminum, aluminum carbide, and aluminum sulfide in the slurry, and does not produce aluminum hydroxide colloid. Instead, it produces sodium metaaluminate, which dissolves in the slurry. When the slurry is filtered, there is no aluminum hydroxide colloid to clog the filter cloth.

[0017] After slurry filtration, the present invention produces a sodium aluminate brine. To dispose of the sodium aluminate brine, carbon dioxide gas is introduced into the brine precipitation tank. The brine and gas react to form aluminum hydroxide precipitate. This precipitate is uniformly stirred in a precipitation slurry mixing tank and then returned to a vacuum belt filter. The resulting pure brine can be fed into an MVR evaporator for salt crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The utility model is a flow chart of a filter cloth anti-clogging system of a vacuum belt filter for aluminum ash processing.

[0019] The numbers in the accompanying drawings are: 1 raw material slurry supply pipeline, 2 sodium hydroxide solution storage tank, 3 reaction tank, 4 vacuum belt filter, 5 concentrated brine precipitation tank, 6MVR evaporator, 7 precipitation slurry stirring tank, 8 carbon dioxide preparation device, 81 carbon dioxide compressor, 82 carbon dioxide storage tank, 9 precipitation slurry pump, 10 feed main valve, 11 connecting pipe, 12 conveying slurry pump, 13 feed valve, 14 solution delivery pipe, 15 flow meter, 16 metering pump, 17 liquid outlet pipe, 18 liquid outlet valve, 19 three-way pipe, 20 air supply valve, 21 pure brine pump, 22 pure brine pipe, 23 pure brine valve, 24 feed pipe. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings:

[0021] like Figure 1 As shown, the anti-clogging system for the filter cloth of the vacuum belt filter for aluminum ash treatment ensures that the salt slag aluminum ash during the hydrolysis reaction does not generate aluminum hydroxide colloid, thus preventing filter clogging. The anti-clogging system includes a raw material slurry supply pipeline 1, a sodium hydroxide solution storage tank 2, multiple reaction tanks 3, a vacuum belt filter 4, multiple brine precipitation tanks 5, an MVR evaporator 6, a precipitation slurry stirring tank 7, and a carbon dioxide production device 8.

[0022] The tail end of the raw material slurry supply pipe 1 is connected to the first reaction tank 3, where it is connected to the top of the reaction tank 3. There are three reaction tanks 3, which are connected in series. Specifically, a connecting pipe 11 is provided between two adjacent reaction tanks 3 to achieve this connection. One end of the connecting pipe 11 connects to the bottom of the preceding reaction tank 3, and the other end connects to the top of the succeeding reaction tank 3. A slurry delivery pump 12 is provided on the connecting pipe 11. In this way, the connecting pipe 11 and the slurry delivery pump 12 can promote the flow of raw material slurry between the three reaction tanks 3 in sequence, ensuring a thorough hydrolysis reaction.

[0023] The last reaction tank 3 is connected to the liquid inlet end of the vacuum belt filter 4, that is, a connecting pipe 11 is also provided between the bottom end of the last reaction tank 3 and the liquid inlet end of the vacuum belt filter 4, and a slurry delivery pump 12 is also arranged on the connecting pipe 11 to supply the slurry to the vacuum belt filter 4.

[0024] To prevent the formation of colloids during the hydrolysis reaction of the raw material slurry in reaction tank 3, a sodium hydroxide solution storage tank 2 is connected to the raw material slurry supply pipeline 1. The sodium hydroxide solution storage tank 2 contains a 25% sodium hydroxide solution. A solution delivery pipe 14 is provided between the sodium hydroxide solution storage tank 2 and the raw material slurry supply pipeline 1 to connect them. The sodium hydroxide solution can be supplied to the raw material slurry, thereby achieving mixing of the two, and then passing them into the first reaction tank 3.

[0025] To achieve the desired concentration ratio, a flowmeter 15 is installed on the raw material slurry supply pipeline 1 to monitor the flow rate of the raw material slurry supply. Simultaneously, a metering pump 16 is installed on the solution delivery pipe 14. This pump not only delivers the sodium hydroxide solution but also monitors the discharge flow rate. The combined flow rate of the raw material slurry supply and the discharge flow rate of the sodium hydroxide solution ensure that the sodium hydroxide content in the raw material slurry reaches 2%, allowing the reaction to occur without forming aluminum hydroxide colloid, but rather forming sodium metaaluminate, which dissolves in the slurry.

[0026] The slurry without aluminum hydroxide colloid is passed into the vacuum belt filter 4 to avoid clogging of the filter cloth. The vacuum belt filter 4 is a prior art that can continuously separate solids and liquids through the circulation of the belt, and the liquid is sucked out under negative pressure.

[0027] The liquid outlet of the vacuum belt filter 4 is connected in parallel to multiple concentrated brine precipitation tanks 5. Specifically, the liquid outlet pipe 17 is connected in parallel to three concentrated brine precipitation tanks 5. The purpose of providing three concentrated brine precipitation tanks 5 is to alternately carry out the processes of concentrated brine intake, reaction, sedimentation, aging, discharge of supernatant liquid, and discharge of aluminum hydroxide and ash settled at the bottom to ensure stable and continuous production.

[0028] The liquid outlet of the vacuum belt filter 4 is connected to a liquid outlet pipe 17. A liquid outlet valve 18 is provided between the liquid outlet pipe 17 and each concentrated brine precipitation tank 5. By controlling the liquid outlet valve 18, the sodium metaaluminate concentrated brine liquid filtered by the vacuum belt filter 4 can be controlled to flow into a separate concentrated brine precipitation tank 5.

[0029] The concentrated brine settling tank 5 has a conical bottom and serves as a separation device. To dispose of the sodium metaaluminate concentrated brine, the bottom of the tank is connected to a carbon dioxide production unit 8, allowing carbon dioxide gas to be introduced into the tank for aeration. This allows the soluble sodium metaaluminate in the brine to react with the carbon dioxide to form aluminum hydroxide precipitate, which settles in the tank.

[0030] In this embodiment, the carbon dioxide production device 8 includes a carbon dioxide compressor 81 and a carbon dioxide storage tank 82. The carbon dioxide compressor 81 is a compressor used to pressurize and transport carbon dioxide gas. A three-way pipe 19 connects the carbon dioxide compressor 81 and the carbon dioxide storage tank 82. One branch of the three-way pipe 19 is connected in parallel to the bottom of the three concentrated brine precipitation tanks 5. An air supply valve 20 is provided between one branch of the three-way pipe 19 and each concentrated brine precipitation tank 5, allowing for targeted aeration of one of the concentrated brine precipitation tanks 5.

[0031] The sodium metaaluminate concentrated brine in the concentrated brine precipitation tank 5 produces a slurry of solid matter and pure brine liquid after aeration. The slurry gathers in the concentrated brine precipitation tank 5, and the pure brine liquid is on top of the slurry. The slurry and the pure brine liquid are layered up and down.

[0032] To dispose of pure brine, the concentrated brine precipitation tank 5 is connected to the MVR evaporator 6, and the pure brine separated from the concentrated brine precipitation tank 5 can be passed into the MVR evaporator 6. Specifically, the MVR evaporator 6 is connected to a pure brine pipe 22 with a pure brine pump 21. The pure brine pipe 22 is connected in parallel to multiple concentrated brine precipitation tanks 5. The pure brine pipe 22 is connected to the side wall of the concentrated brine precipitation tank 5, and the connection is spaced a certain height from the bottom of the concentrated brine precipitation tank 5. A pure brine valve 23 is provided between the pure brine pipe 22 and each concentrated brine precipitation tank 5. When a pure brine valve 23 is opened, the pure brine in the corresponding concentrated brine precipitation tank 5 flows into the pure brine pipe 22. At the same time, under the action of the pure brine pump 21, the pure brine is passed into the MVR evaporator 6.

[0033] The slurry of solid matter separated from the concentrated brine precipitation tank 5 is collected at the bottom. In order to dispose of the slurry, the concentrated brine precipitation tank 5 is connected to the inlet of the precipitation slurry stirring tank 7, so that the slurry can be passed into the precipitation slurry stirring tank 7. Specifically, the inlet of the precipitation slurry stirring tank 7 is connected to a feed pipe 24, which is connected in parallel to the bottom of multiple concentrated brine precipitation tanks 5. A feed valve 13 is provided between the feed pipe 24 and each concentrated brine precipitation tank 5. Opening a single feed valve 13 can control the slurry in the corresponding concentrated brine precipitation tank 5 to enter the feed pipe 24.

[0034] The feed pipe 24 is provided with a sedimentation slurry pump 9, which can pass the slurry into the sedimentation slurry mixing tank 7, and the slurry can be uniformly stirred in the sedimentation slurry mixing tank 7. The feed pipe 24 is also provided with a feed main valve 10 to achieve overall control of the feed pipe 24 on and off.

[0035] The outlet of the sedimentation slurry mixing tank 7 is connected to the vacuum belt filter 4. Specifically, a discharge pipe 25 is connected to the outlet of the sedimentation slurry mixing tank 7, which is in communication with the vacuum belt filter 4. This discharge pipe 25 is also equipped with a sedimentation slurry pump 9. The evenly stirred slurry is then returned to the vacuum belt filter 4 by the action of the sedimentation slurry pump 9. It is important to note that the end of the connecting pipe 11 of the last reaction tank 3 is connected to the front of the vacuum belt filter 4, and the discharge pipe 25 is connected to the middle of the vacuum belt filter 4. This allows the slurry to flow to the upper layer of the slightly dried filter cake.

[0036] The principle of this utility model is as follows: a flow meter 15 is installed on the supply pipeline leading from the raw material slurry to the first reaction tank 3. A sodium hydroxide solution storage tank 2 is also installed. This storage tank is connected to the raw material slurry supply pipeline 1 via a solution delivery pipe 14 equipped with a metering pump 16. The flow rate data monitored by the flow meter 15 is used to control the amount of 25% sodium hydroxide solution added to the raw material slurry, ensuring that the sodium hydroxide content in the slurry reaches 2%. Within the reaction tank 3, the sodium hydroxide reacts with the harmful substances aluminum nitride, metallic aluminum, aluminum carbide, and aluminum sulfide in the slurry. Instead of forming aluminum hydroxide colloid, it forms sodium metaaluminate, which dissolves in the slurry.

[0037] The aluminum ash slurry after the hydrolysis reaction is filtered in a vacuum belt filter 4. Because the sodium metaaluminate dissolves in the slurry, there is no aluminum hydroxide colloid to clog the filter cloth during filtration. Filter cake and liquid are produced during slurry filtration. The liquid is sodium metaaluminate concentrated brine. The sodium metaaluminate concentrated brine obtained after slurry filtration flows through the liquid outlet pipe 17 into one of the concentrated brine tanks. Carbon dioxide gas is introduced into the bottom of the concentrated brine precipitation tank 5 through the carbon dioxide production device 8. The soluble sodium metaaluminate in the concentrated brine reacts with the carbon dioxide to form an aluminum hydroxide precipitate, which settles and ages in the concentrated brine precipitation tank 5 for 24 hours.

[0038] After the concentrated brine settles, pure brine is obtained. This pure brine is pumped through pure brine pump 21 and enters the MVR evaporator 6 along pure brine pipe 22 for crystallization. After settling, aluminum hydroxide and slurry are simultaneously produced and pumped to the precipitation slurry mixing tank 7. After uniform mixing, they are pumped to the vacuum belt filter 4. This slurry flows over the slightly dry filter cake, effectively forming a top-to-bottom layer distribution. This ensures a stable, non-volatile alumina content in the finished ash after drying. Furthermore, the filter cake is used as a filter layer, trapping aluminum hydroxide particles less than 30 μm in the filter cake, preventing them from contacting and clogging the filter cloth or entering the concentrated brine. The beneficial aluminum element remains in the filter cake.

[0039] It should be noted that since sedimentation and aging take a long time, in order to ensure continuous production operation, three concentrated brine precipitation tanks 5 are arranged for alternating use. For example, while the first concentrated brine precipitation tank 5 is being fed with concentrated brine and aerated for sedimentation and aging, concentrated brine can be fed into the second or third concentrated brine precipitation tank 5 to continue the above process. After the sedimentation time of the first concentrated brine precipitation tank 5 is reached, the slurry and pure brine are separated, and then concentrated brine and carbon dioxide gas are introduced. At this time, the slurry and pure brine in the second or third concentrated brine precipitation tank 5 can be separated. This reciprocating process can ensure the stable and continuous development of production operations.

[0040] The embodiments described above are only preferred embodiments of the present invention and do not limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made based on the structure, features and principles described in the patent scope of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. Aluminum ash treatment vacuum belt filter cloth anti-clogging system, characterized by: It includes a raw material slurry supply pipeline (1), a sodium hydroxide solution storage tank (2), a plurality of reaction tanks (3), a vacuum belt filter (4), a plurality of concentrated brine precipitation tanks (5), an MVR evaporator (6), a precipitation slurry stirring tank (7) and a carbon dioxide production device (8); The raw material slurry supply pipeline (1) is connected to the sodium hydroxide solution storage tank (2), and the tail end of the raw material slurry supply pipeline (1) is connected to the first reaction tank (3). The multiple reaction tanks (3) are connected in series in sequence, and the last reaction tank (3) is connected to the liquid inlet end of the vacuum belt filter (4); The liquid outlet of the vacuum belt filter (4) is connected in parallel to a plurality of concentrated brine precipitation tanks (5), and the concentrated brine precipitation tanks (5) are connected to the MVR evaporator (6); the concentrated brine precipitation tanks (5) are connected to the inlet of the precipitation slurry stirring tank (7), and the outlet of the precipitation slurry stirring tank (7) is connected to the vacuum belt filter (4); and the bottom of the concentrated brine precipitation tank (5) is connected to the carbon dioxide preparation device (8).

2. The filter cloth anti-clogging system for vacuum belt filter for aluminum ash treatment according to claim 1 is characterized in that: The raw material slurry supply pipeline (1) is provided with a flow meter (15), the concentration of the sodium hydroxide solution in the sodium hydroxide solution storage tank (2) is 25%, and a solution delivery pipe (14) is provided between the sodium hydroxide solution storage tank (2) and the raw material slurry supply pipeline (1) for communication, and a metering pump (16) is provided on the solution delivery pipe (14).

3. The filter cloth anti-clogging system for vacuum belt filter for aluminum ash treatment according to claim 1 is characterized in that: A connecting pipe (11) is provided between two adjacent reaction tanks (3) for communication, one end of the connecting pipe (11) being connected to the bottom end of the preceding reaction tank (3) and the other end being connected to the top end of the following reaction tank (3); a connecting pipe (11) is also provided between the bottom end of the last reaction tank (3) and the liquid inlet end of the vacuum belt filter (4), and a slurry delivery pump (12) is provided on the connecting pipe (11).

4. The filter cloth anti-clogging system for vacuum belt filter for aluminum ash treatment according to claim 1 is characterized in that: The liquid outlet end of the vacuum belt filter (4) is connected to a liquid outlet pipe (17), the liquid outlet pipe (17) is connected in parallel to a plurality of concentrated brine precipitation tanks (5), and a liquid outlet valve (18) is provided between the liquid outlet pipe (17) and each concentrated brine precipitation tank (5); The MVR evaporator (6) is connected to a pure brine pipe (22) with a pure brine pump (21), the pure brine pipe (22) is connected in parallel to a plurality of concentrated brine precipitation tanks (5), the pure brine pipe (22) is connected to the side walls of the concentrated brine precipitation tanks (5), and a pure brine valve (23) is provided between the pure brine pipe (22) and each concentrated brine precipitation tank (5).

5. The filter cloth anti-clogging system for vacuum belt filter for aluminum ash treatment according to claim 1 is characterized in that: The inlet of the precipitation slurry stirring tank (7) is connected to a feed pipe (24), the feed pipe (24) is connected in parallel to the bottom of a plurality of concentrated brine precipitation tanks (5), and a feed valve (13) is provided between the feed pipe (24) and each concentrated brine precipitation tank (5); The outlet of the precipitation slurry stirring tank (7) is connected to a discharge pipe (25), which is connected to a vacuum belt filter (4). Both the discharge pipe (25) and the feed pipe (24) are provided with a precipitation slurry pump (9), and the feed pipe (24) is also provided with a main feed valve (10).

6. The filter cloth anti-clogging system for vacuum belt filter for aluminum ash treatment according to claim 5, characterized in that: The carbon dioxide preparation device (8) comprises a carbon dioxide compressor (81) and a carbon dioxide storage tank (82). A three-way pipe (19) is connected between the carbon dioxide compressor (81) and the carbon dioxide storage tank (82). A branch of the three-way pipe (19) is connected in parallel to the bottoms of a plurality of concentrated brine precipitation tanks (5). An air supply valve (20) is provided between a branch of the three-way pipe (19) and each concentrated brine precipitation tank (5).

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