Harmless treatment system for salt slag and aluminum ash
By introducing carbon dioxide into the salt slag aluminum ash treatment system to generate aluminum hydroxide precipitation, the problem of excessive treatment time of salt slag aluminum ash is solved, and faster precipitation and higher production efficiency are achieved.
Patent Information
- Application Number
- CN202421530950.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-01
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-07-01
AI Technical Summary
The salt slag aluminum ash treatment time is long, which affects the production progress.
During the precipitation process of the concentrated brine precipitation tank, carbon dioxide is introduced to react with the metaaluminate in the concentrated brine to form aluminium hydroxide precipitation. The ash is wrapped in the precipitation by using the flocculation of aluminum hydroxide to shorten the precipitation time.
The precipitation process is accelerated, the filtration process is reduced, the production efficiency is improved, and the stability and economic benefits of product quality are ensured.
Smart Images
Figure CN223170235U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of aluminum ash treatment, and particularly relates to a harmless treatment system for salt slag aluminum ash. Background Technique
[0002] Aluminum ash is a solid waste generated during the production of electrolytic aluminum or the melting process of aluminum processing. Its main components include aluminum oxide, metallic aluminum, aluminum nitride, and soluble electrolyte salts, etc. According to different treatment links, aluminum ash is divided into primary aluminum ash and secondary aluminum ash. As the residue after aluminum extraction from primary aluminum ash, the metallic aluminum content in secondary aluminum ash is relatively low. Due to the presence of toxic and harmful substances such as nitrides and fluorine and chlorine in aluminum ash, foul-smelling gases and toxic substances are easily generated during the stacking process of aluminum ash, causing great environmental pollution.
[0003] The residue after the secondary aluminum ash is treated with composite salts in a rotary kiln contains a large amount of sodium chloride and potassium chloride, and also a small amount of sodium sulfate, which is also called salt slag aluminum ash. The general treatment process of salt slag aluminum ash is as Figure 1 shown. Water and aluminum ash are proportioned in a batching tank and then enter a reaction tank. The high-temperature mixed gas generated by water and aluminum ash in the reaction tank is cooled and temperature-reduced by a gas-liquid separator and then sent to an ammonia absorption tower. The slurry at the bottom of the reaction tank is filtered by a vacuum belt filter to obtain concentrated brine, light brine, and ash. The light brine goes to the light brine tank, and the ash is dried. The concentrated brine is precipitated in a concentrated brine sedimentation tank to obtain pure brine, which then enters an MVR evaporator, and then through steps such as crystallization and centrifugation to obtain a composite salt product. The slurry containing ash at the bottom of the concentrated brine sedimentation tank enters the vacuum belt filter for filtration again. However, the natural precipitation and aging time of the ash in the concentrated brine sedimentation tank are relatively long, usually more than 48 hours, which affects the production progress. Summary of the Invention
[0004] Aiming at the technical problem of the long treatment time of salt slag aluminum ash, the utility model provides a harmless treatment system for salt slag aluminum ash. By introducing carbon dioxide during the precipitation process in the concentrated brine sedimentation tank, carbon dioxide fully reacts with the meta-aluminate in the concentrated brine to generate aluminum hydroxide precipitation. At the same time, using the flocculation effect of aluminum hydroxide, the ash in the concentrated brine is wrapped in the precipitation and then settles at the bottom of the concentrated brine sedimentation tank, accelerating the precipitation process, shortening the aluminum ash treatment time, and improving production efficiency.
[0005] To achieve the above purpose, the utility model adopts the following technical solutions:
[0006] A harmless treatment system for salt slag aluminum ash, comprising a batching tank, a reaction tank, a vacuum belt filter, a concentrated brine sedimentation tank, a fresh brine tank and an MVR evaporator. The liquid outlet at the bottom of the batching tank is connected to the liquid inlet of the reaction tank. The gas outlet at the top of the reaction tank is connected to an ammonia recovery system. The liquid outlet at the bottom of the reaction tank is connected to the raw material inlet of the vacuum belt filter. The concentrated brine outlet of the vacuum belt filter is connected to the brine inlet at the top of the concentrated brine sedimentation tank. The fresh brine outlet of the vacuum belt filter is connected to the liquid inlet of the fresh brine tank. The liquid outlet of the fresh brine tank is connected to the liquid inlet of the batching tank. The bottom outlet of the concentrated brine sedimentation tank is connected to the raw material inlet of the vacuum belt filter. The net brine outlet at the side of the concentrated brine sedimentation tank is connected to the MVR evaporator. It also includes an air compressor and a carbon dioxide storage tank. The outlet of the air compressor and the outlet of the carbon dioxide storage tank are connected to the bottom outlet of the concentrated brine sedimentation tank.
[0007] In a technical solution, the pipeline at the bottom outlet of the concentrated brine sedimentation tank is divided into a gas pipeline and a slurry pipeline. The air pipeline is connected to the outlet of the air compressor and the outlet of the carbon dioxide storage tank. The slurry pipeline is connected to the raw material inlet of the vacuum belt filter.
[0008] In a preferred technical solution, the harmless treatment system for salt slag aluminum ash of the present utility model further includes a sedimentation storage tank. The slurry pipeline is connected to the inlet of the sedimentation storage tank. The outlet of the sedimentation storage tank is connected to the raw material inlet of the vacuum belt filter.
[0009] In a preferred technical solution, the harmless treatment system for salt slag aluminum ash of the present utility model further includes a sodium hydroxide solution storage tank. The outlet of the sodium hydroxide solution storage tank is connected to the liquid inlet of the reaction tank.
[0010] In a preferred technical solution, the ammonia recovery system in the harmless treatment system for salt slag aluminum ash of the present utility model includes a gas-liquid separator, an ammonia absorption tower and an ammonia water finished product tank. The gas outlet at the top of the reaction tank is connected to the gas inlet of the gas-liquid separator. The gas outlet of the upper gas collecting cylinder of the gas-liquid separator is connected to the gas inlet of the ammonia absorption tower. The liquid outlet at the bottom of the gas-liquid separator is connected to the liquid inlet of the fresh brine tank. The absorbent inlet of the ammonia absorption tower is connected to a water pipe. The ammonia water outlet at the bottom of the ammonia absorption tower is connected to the ammonia water finished product tank.
[0011] Compared with the prior art, the beneficial effects of the present utility model are as follows:
[0012] The utility model adds an air compressor and a carbon dioxide storage tank to the pulp recovery system. By introducing carbon dioxide during the precipitation process in the concentrated brine sedimentation tank, carbon dioxide fully reacts with the meta-aluminate ions in the concentrated brine to form aluminum hydroxide precipitate. At the same time, by utilizing the flocculation effect of aluminum hydroxide, the ash in the concentrated brine is wrapped in the precipitate and then settles at the bottom of the concentrated brine sedimentation tank, accelerating the precipitation process, making the aluminum ash precipitation more complete, reducing a filtration process, shortening the aluminum ash treatment time, and improving production efficiency.
[0013] The utility model adds a precipitation storage tank to the pulp recovery system. Before the precipitation slurry enters the vacuum belt filter, the precipitation slurry is sent to the precipitation storage tank, and after further stirring the precipitation slurry evenly, it is pumped to the vacuum belt filter, ensuring the stability of the alumina content in the finished ash after the filter cake is dried, with no fluctuation in the alumina content in the filter cakes of different batches, and ensuring the quality of the sold products.
[0014] The utility model also includes a sodium hydroxide solution storage tank in the reaction system. Since the pH of the pulp is increased, it promotes the dissolution of aluminum hydroxide during the reaction process, also speeds up the reaction rates of aluminum nitride, metallic aluminum, aluminum carbide, and aluminum sulfide with water, reducing the time in the reaction stage; it also reduces the dissolution of ammonia in the pulp, thereby increasing the ammonia content in the high-temperature gas, and further increasing the ammonia water production of the ammonia recovery system. At the same time, it increases the production of combustible gases such as hydrogen and methane, improving economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a structural schematic diagram of a prior art harmless treatment system for salt slag aluminum ash.
[0016] Figure 2 It is one of the structural schematic diagrams of the harmless treatment system for salt slag aluminum ash after the transformation of the utility model.
[0017] Figure 3 It is another structural schematic diagram of the harmless treatment system for salt slag aluminum ash after the transformation of the utility model.
[0018] Figure 4 It is the third structural schematic diagram of the harmless treatment system for salt slag aluminum ash after the transformation of the utility model.
[0019] Reference numerals in the drawings: 1 is a batching tank, 2 is a reaction tank, 3 is a gas-liquid separator, 4 is an ammonia absorption tower, 5 is an ammonia water finished product tank, 6 is a vacuum belt filter, 7 is a concentrated brine sedimentation tank, 8 is an MVR evaporator, 9 is a fresh brine tank, 10 is an air compressor, 11 is a carbon dioxide storage tank, 12 is a sodium hydroxide solution storage tank, 13 is a precipitation storage tank. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0020] The following embodiments are used to illustrate the utility model, but are not used to limit the protection scope of the utility model.
[0021] Example 1
[0022] As Figure 2 shown, a harmless treatment system for salt slag and aluminum ash of the present utility model includes a batching tank 1, a reaction tank 2, a gas-liquid separator 3, an ammonia absorption tower 4, an ammonia water finished product tank 5, a vacuum belt filter 6, a concentrated brine sedimentation tank 7, a fresh brine tank 9, an MVR evaporator 8, an air compressor 10 and a carbon dioxide storage tank 11.
[0023] In the present utility model, the batching tank 1 and the reaction tank 2 form a reaction system. The liquid outlet at the bottom of the batching tank 10 is connected to the liquid inlet of the reaction tank 2, and the gas outlet at the top of the reaction tank 2 is connected to the ammonia recovery system. The water for batching comes from the fresh brine in the fresh brine tank 9. After the water and aluminum ash are batched in the batching tank 1, they enter the reaction tank 2, and high-temperature mixed gas and slurry are generated in the reaction tank 2.
[0024] In the present utility model, the gas-liquid separator 3, the ammonia absorption tower 4 and the ammonia water finished product tank 5 form an ammonia recovery system. The gas outlet at the top of the reaction tank 2 is connected to the gas inlet of the gas-liquid separator 3. The gas outlet of the upper gas collecting cylinder of the gas-liquid separator 3 is connected to the gas inlet of the ammonia absorption tower 4. The liquid outlet at the bottom of the gas-liquid separator 3 is connected to the liquid inlet of the fresh brine tank 9. The absorbent inlet of the ammonia absorption tower 4 is connected to a water pipe, and the ammonia water outlet at the bottom of the ammonia absorption tower 4 is connected to the ammonia water finished product tank 5. The high-temperature mixed gas generated in the reaction tank 2 is sent to the ammonia gas absorption tower 4 after being cooled down by the gas-liquid separator 3. The ammonia gas is absorbed by water in the absorption tower, and the ammonia water enters the ammonia water finished product tank 5. The ammonia water at the bottom of the gas-liquid separator 3 returns to the fresh brine tank 9 and then goes to the batching tank 1 for batching.
[0025] In the present utility model, the vacuum belt filter 6, the concentrated brine sedimentation tank 7, the fresh brine tank 9, the MVR evaporator 8, the air compressor 10 and the carbon dioxide storage tank 11 form a slurry recovery system. The liquid outlet at the bottom of the reaction tank 2 is connected to the raw material inlet of the vacuum belt filter 6. The concentrated brine outlet of the vacuum belt filter 6 is connected to the brine inlet at the top of the concentrated brine sedimentation tank 7. The fresh brine outlet of the vacuum belt filter 6 is connected to the liquid inlet of the fresh brine tank 9. The liquid outlet of the fresh brine tank 9 is connected to the liquid inlet of the batching tank 1. The bottom outlet of the concentrated brine sedimentation tank 7 is connected to the raw material inlet of the vacuum belt filter 6. The net brine outlet at the side of the concentrated brine sedimentation tank 7 is connected to the MVR evaporator 8. The outlet of the air compressor 10 and the outlet of the carbon dioxide storage tank 11 are connected to the bottom outlet of the concentrated brine sedimentation tank 7. The vacuum belt filter 6 generally adopts a five-stage vacuum belt filter, including a mother liquor area, a four-stage washing area and a drying area. The liquid outlet of the mother liquor area corresponds to the concentrated brine outlet, the liquid outlet of the first-stage washing area corresponds to the fresh brine outlet, and the drying area corresponds to the filter cake ash outlet.
[0026] Further, for convenient operation, the bottom outlet pipeline of the concentrated brine sedimentation tank 7 is divided into a gas pipeline and a slurry pipeline, and corresponding control valves are provided on the pipelines. The air pipeline is connected to the outlets of the air compressor 10 and the carbon dioxide storage tank 11, and valves are respectively provided on the corresponding medium pipelines. The slurry pipeline is connected to the raw material inlet of the vacuum belt filter 6.
[0027] The process operation of the pulp recovery system is as follows: The pulp at the bottom of the reaction tank 2 is filtered by the vacuum belt filter 6 to obtain concentrated brine, fresh brine, and ash. The concentrated brine obtained by filtration contains ash and sodium metaaluminate. After the concentrated brine enters the concentrated brine sedimentation tank 7, carbon dioxide is first introduced into the concentrated brine sedimentation tank 7 through the air pipeline. After aeration and stirring for 5 minutes, the carbon dioxide fully reacts with the metaaluminate ions in the concentrated brine to produce aluminum hydroxide precipitate. At the same time, by using the flocculation effect of aluminum hydroxide, the ash in the concentrated brine is wrapped in the precipitate and then settles at the bottom of the concentrated brine sedimentation tank 7, accelerating the precipitation process. After aging for 24 hours, pure brine is discharged from the side net brine outlet of the concentrated brine sedimentation tank 7. The pure brine enters the MVR evaporator and then obtains composite salt products through steps such as crystallization and centrifugation. After the pure concentrated brine is discharged, air is introduced into the concentrated brine sedimentation tank 7 through the air pipeline again, and aeration and stirring are carried out for 5 minutes. The precipitate slurry is discharged from the slurry pipeline of the concentrated brine sedimentation tank 7 and sent to the vacuum belt filter 6, and the precipitate remains in the filter cake during filtration.
[0028] In the present utility model, by introducing carbon dioxide during the precipitation process of the concentrated brine sedimentation tank 7, the carbon dioxide fully reacts with the metaaluminate ions in the concentrated brine to produce aluminum hydroxide precipitate. At the same time, by using the flocculation effect of aluminum hydroxide, the ash in the concentrated brine is wrapped in the precipitate and then settles at the bottom of the concentrated brine sedimentation tank 7, accelerating the precipitation process, making the precipitation of aluminum ash more complete, reducing one filtration process, shortening the aluminum ash treatment time, and improving production efficiency.
[0029] Example 2
[0030] As Figure 3 shown, the reaction system of a harmless treatment system for salt slag and aluminum ash of the present utility model further includes a sodium hydroxide solution storage tank 12. There are 3 reaction tanks 2 in the reaction system, and the outlet of the sodium hydroxide solution storage tank 12 is connected to the liquid inlet of the first reaction tank 2.
[0031] Since components such as aluminum nitride, metallic aluminum, aluminum carbide, and aluminum sulfide in aluminum ash react with water to produce high-temperature gases and aluminum hydroxide precipitate at the same time, to prevent the precipitate from accumulating at the bottom of the reaction tank 2 and being unfavorable for discharge, it is necessary to dissolve the aluminum hydroxide. A simple method is to adjust the pH of the pulp in the reaction tank 2 to above 12 to promote the dissolution of aluminum hydroxide, which will also accelerate the reaction rate of aluminum nitride, metallic aluminum, aluminum carbide, and aluminum sulfide with water and reduce the time in the reaction stage. Since ammonia is highly soluble in water and makes the pH of the pulp already alkaline, the amount of sodium hydroxide used in the reaction system does not need to be too much. Generally, the amount of sodium hydroxide solution used accounts for 2% of the total pulp amount in the reaction tank. In addition, since adding sodium hydroxide increases the pH of the pulp, it will also reduce the dissolution of ammonia in the pulp, thereby increasing the ammonia content in the high-temperature gas, further increasing the ammonia water production of the ammonia recovery system, and at the same time increasing the production of combustible gases such as hydrogen and methane, improving economic benefits.
[0032] Example 3
[0033] As Figure 4 shown, a harmless treatment system for salt slag aluminum ash of the present utility model further includes a precipitation storage tank 13. The slurry pipeline is connected to the inlet of the precipitation storage tank 13, and the outlet of the precipitation storage tank 13 is connected to the raw material inlet of the vacuum belt filter 6.
[0034] If the precipitation slurry discharged from the slurry pipeline of the concentrated brine precipitation tank 7 is directly sent to the vacuum belt filter 6, it will cause uneven distribution of alumina in the filter cake after drying. Therefore, before the precipitation slurry enters the vacuum belt filter 6, the precipitation slurry is sent to the precipitation storage tank 13. A stirrer is arranged in the precipitation storage tank 13, and the precipitation slurry is further stirred evenly and then pumped to the vacuum belt filter 6 to ensure the stability of the alumina content in the finished ash after the filter cake is dried, and there is no fluctuation in the alumina content in the filter cakes of different batches, ensuring the quality of the externally sold products.
[0035] In one embodiment, as Figure 4 shown, a total of three concentrated brine precipitation tanks 7 are arranged in the pulp treatment system, and processes such as feeding concentrated brine, charging carbon dioxide, reacting, settling, aging, discharging the upper pure concentrated brine, discharging the bottom precipitation, and ash slurry are carried out alternately to make the production stable and continuous.
[0036] The above-mentioned embodiments are only the preferred embodiments of the present utility model, which are only used to explain the present utility model and do not limit the scope of implementation of the present utility model. For those skilled in the art of this technology, of course, other implementation manners can be easily made according to the technical content disclosed in this specification by means of replacement or change. Therefore, all changes and improvements made on the principle of the present utility model should be included within the scope of the patent application of the present utility model.
Claims
1. A harmless treatment system for salt slag aluminum ash, comprising a batching tank (1), a reaction tank (2), a vacuum belt filter (6), a concentrated brine sedimentation tank (7), a fresh brine tank (9) and an MVR evaporator (8). The liquid outlet at the bottom of the batching tank (10) is connected to the liquid inlet of the reaction tank (2). The gas outlet at the top of the reaction tank (2) is connected to an ammonia recovery system. The liquid outlet at the bottom of the reaction tank (2) is connected to the raw material inlet of the vacuum belt filter (6). The concentrated brine outlet of the vacuum belt filter (6) is connected to the brine inlet at the top of the concentrated brine sedimentation tank (7). The fresh brine outlet of the vacuum belt filter (6) is connected to the liquid inlet of the fresh brine tank (9). The liquid outlet of the fresh brine tank (9) is connected to the liquid inlet of the batching tank (1). The bottom outlet of the concentrated brine sedimentation tank (7) is connected to the raw material inlet of the vacuum belt filter (6). The net brine outlet at the side of the concentrated brine sedimentation tank (7) is connected to the MVR evaporator (8), characterized in that, It also includes an air compressor (10) and a carbon dioxide storage tank (11), and the outlet of the air compressor (10) and the outlet of the carbon dioxide storage tank (11) are connected to the bottom outlet of the concentrated brine sedimentation tank (7).
2. The harmless treatment system for salt slag and aluminum ash according to claim 1, wherein, The pipeline at the bottom outlet of the concentrated brine sedimentation tank (7) is divided into a gas pipeline and a slurry pipeline. The air pipeline is connected to the outlet of the air compressor (10) and the outlet of the carbon dioxide storage tank (11), and the slurry pipeline is connected to the raw material inlet of the vacuum belt filter (6).
3. The harmless treatment system for salt slag aluminum ash according to claim 1 or 2, characterized in that, It also includes a sedimentation storage tank (13). The slurry pipeline is connected to the inlet of the sedimentation storage tank (13), and the outlet of the sedimentation storage tank (13) is connected to the raw material inlet of the vacuum belt filter (6).
4. The harmless treatment system for salt slag aluminum ash according to claim 1, wherein It also includes a sodium hydroxide solution storage tank (12), and the outlet of the sodium hydroxide solution storage tank (12) is connected to the liquid inlet of the reaction tank (2).
5. The harmless treatment system for salt slag aluminum ash according to claim 1, wherein, The ammonia recovery system includes a gas-liquid separator (3), an ammonia absorption tower (4) and an ammonia water product tank (5). The gas outlet at the top of the reaction tank (2) is connected to the gas inlet of the gas-liquid separator (3). The gas outlet of the upper gas collecting cylinder of the gas-liquid separator (3) is connected to the gas inlet of the ammonia absorption tower (4). The liquid outlet at the bottom of the gas-liquid separator (3) is connected to the liquid inlet of the fresh brine tank (9). The absorbent inlet of the ammonia absorption tower (4) is connected to a water pipe, and the ammonia water outlet at the bottom of the ammonia absorption tower (4) is connected to the ammonia water product tank (5).