Ore pulp treatment system in salt slag aluminum ash treatment
By adding barium chloride solution and sulfate to the aluminum ash treatment system to form barium sulfate precipitation, and improving the removal rate through air aeration and stirring, the problem of sodium sulfate decomposition and producing sulfur dioxide at high temperature is solved, and the sulfur dioxide emissions in the rotary furnace exhaust gas are significantly reduced.
Patent Information
- Application Number
- CN202421530952.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-01
- Publication Date
- 2025-04-15
- Estimated Expiration
- 2034-07-01
AI Technical Summary
During the aluminum ash treatment, sodium sulfate is enriched in the MVR evaporator, causing it to decompose into sulfur dioxide at high temperatures, corroding the equipment and seriously polluting the environment.
The solution of barium chloride is added to the slurry treatment system to form barium sulfate precipitation with sulfate, and the sulfate removal rate is increased by air aeration, so that the barium sulfate precipitation remains in the filter cake and no longer enters the composite salt product.
It effectively avoids the decomposition of sodium sulfate at high temperature to produce sulfur dioxide, reduces the sulfur dioxide emissions in the rotary furnace exhaust gas, and makes it reach the national emission standard of 5mg/m3, which is far lower than 50mg/m3.
Smart Images
Figure CN222752623U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of aluminum ash treatment, and in particular relates to a slurry treatment system in salt slag aluminum ash treatment. Background Art
[0002] Aluminum ash is solid waste generated during the production of electrolytic aluminum or aluminum processing and smelting. Its main components include alumina, metallic aluminum, aluminum nitride, and soluble electrolyte salts. According to different processing links, aluminum ash is divided into primary aluminum ash and secondary aluminum ash. Secondary aluminum ash is the residue after aluminum extraction from primary aluminum ash, and its metallic aluminum content is relatively low. Due to the presence of nitrides and toxic and harmful substances such as fluorine and chlorine in aluminum ash, aluminum ash is prone to produce odorous gases and toxic substances during storage, which causes great pollution to the environment.
[0003] The residue after the secondary aluminum ash is treated with compound salt in a rotary kiln contains a large amount of sodium chloride, potassium chloride, and a small amount of sodium sulfate, which is also called salt slag aluminum ash. Figure 1 As shown, water and aluminum ash are mixed in a batching tank and then enter the reaction tank. The high-temperature mixed gas generated by water and aluminum ash in the reaction tank is sent to the ammonia absorption tower after being cooled by a gas-liquid separator. The slurry at the bottom of the reaction tank is filtered by a vacuum belt filter to obtain concentrated brine, dilute brine and ash. The dilute brine goes to the dilute brine tank, and the ash is dried. The concentrated brine is precipitated in a concentrated brine precipitation tank to obtain pure brine, which then enters the MVR evaporator and is crystallized, centrifuged and other steps to obtain a composite salt product. The ash-containing slurry at the bottom of the concentrated brine precipitation tank enters the vacuum belt filter again for filtration. However, the concentrated brine after being filtered by the vacuum belt filter contains about 0.8% sodium sulfate. Directly entering the MVR evaporator will cause the following problems: sodium sulfate is enriched in the MVR evaporator and crystallized together with sodium chloride and potassium chloride. Sodium sulfate is mixed in the composite salt product (the content reaches about 3%). The local temperature of the rotary kiln using the composite salt reaches 2000℃. Part of the sodium sulfate decomposes into sulfur dioxide at high temperature, which will corrode the equipment. After the rotary kiln exhaust is desulfurized, the maximum sulfur dioxide emission still reaches 2000mg / m 3 , which seriously pollutes the environment. Therefore, it is necessary to reduce the enrichment of sulfate ions in the process of aluminum ash treatment and reduce environmental pollution. Summary of the invention
[0004] The utility model aims at the technical problem of sulfate radical enrichment in the process of aluminum ash slurry treatment, provides a slurry treatment system in salt slag aluminum ash treatment, adds a barium chloride storage tank and an air compressor, adds a barium chloride solution into a concentrated brine precipitation tank, generates barium sulfate precipitate with sulfate radical, introduces air into the concentrated brine precipitation tank for aeration and stirring, and finally makes the barium sulfate precipitate no longer enter the composite salt product, thereby preventing the high-temperature decomposition of sodium sulfate to produce sulfur dioxide during the process of using the composite salt in a rotary kiln, so that the exhaust gas of the rotary kiln meets the emission standard.
[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0006] A slurry processing system in salt slag aluminum ash processing comprises a batching tank, a reaction tank, a vacuum belt filter, a concentrated brine precipitation tank, a desalinated brine tank and an MVR evaporator, wherein the liquid outlet of the desalinated brine tank is connected to the liquid inlet of the batching tank, the liquid outlet at the bottom of the batching tank is connected to the liquid inlet of the reaction tank, 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 precipitation tank, the desalinated brine outlet of the vacuum belt filter is connected to the liquid inlet of the desalinated brine tank, the liquid outlet of the desalinated brine tank is connected to the liquid inlet of the batching tank, the bottom outlet of the concentrated brine precipitation tank is connected to the raw material inlet of the vacuum belt filter, and the net brine outlet on the side of the concentrated brine precipitation tank is connected to the MVR evaporator, characterized in that it also comprises a barium chloride storage tank and an air compressor, the liquid outlet of the barium chloride storage tank is connected to the barium chloride inlet at the top of the concentrated brine precipitation tank, and the air compressor outlet is connected to the bottom outlet of the concentrated brine precipitation tank.
[0007] In a preferred technical solution, a metering pump is provided on the pipeline connecting the liquid outlet of the barium chloride storage tank to the barium chloride inlet at the top of the concentrated brine precipitation tank 7 .
[0008] In a preferred technical solution, the bottom outlet pipe of the concentrated brine precipitation tank is divided into an air pipe and a slurry pipe, the air pipe is connected to an air compressor, and the slurry pipe is connected to a raw material inlet of a vacuum belt filter.
[0009] In a preferred technical solution, a liquid level meter is provided on the concentrated brine precipitation tank.
[0010] Compared with the prior art, the beneficial effects of the present invention are:
[0011] The utility model adds a barium chloride storage tank and an air compressor to the slurry treatment system, adds a barium chloride solution to the concentrated brine precipitation tank, and generates barium sulfate precipitation with sulfate. In addition, air is introduced into the concentrated brine precipitation tank for aeration and stirring in the sampling and analysis process, the precipitation reaction process, and the slurry discharge process, so that the sulfate removal rate is higher, and finally the barium sulfate precipitation is retained in the filter cake instead of entering the composite salt product, thereby preventing the high-temperature decomposition of sodium sulfate to produce sulfur dioxide in the process of using the composite salt in the rotary kiln, thereby reducing the sulfur dioxide content of the rotary kiln tail gas to 5mg / m 3 , far below the national emission standard of 50mg / m 3 . BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 This is a schematic diagram of the structure of a slurry treatment system in salt slag aluminum ash treatment before modification.
[0013] Figure 2 It is a schematic structural diagram of a modified slurry processing system in salt slag aluminum ash processing according to the utility model.
[0014] Markings in the attached figure: 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 finished product tank, 6 is a vacuum belt filter, 7 is a concentrated brine precipitation tank, 8 is an MVR evaporator, 9 is a desalinated brine tank, 10 is a barium chloride storage tank, and 11 is an air compressor. DETAILED DESCRIPTION
[0015] The following embodiments are used to illustrate the present invention, but are not used to limit the protection scope of the present invention.
[0016] like Figure 2 As shown, the utility model is a slurry processing system in the treatment of salt slag aluminum ash, which includes a batching tank 1, three reaction tanks 2, a vacuum belt filter 6, three concentrated brine precipitation tanks 7, a dilute brine tank 9 and an MVR evaporator 8. The bottom liquid outlet of the batching tank 1 is connected to the liquid inlet of the reaction tank 2 in sequence, the bottom liquid outlet of each 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 top brine inlet of the concentrated brine precipitation tank 7, the dilute brine outlet of the vacuum belt filter 6 is connected to the liquid inlet of the dilute brine tank 9, the liquid outlet of the dilute brine tank 9 is connected to the liquid inlet of the batching tank 1, the bottom outlet of the concentrated brine precipitation tank 7 is connected to the raw material inlet of the vacuum belt filter 6, and the side net brine outlet of the concentrated brine precipitation tank 7 is connected to the MVR evaporator 8.
[0017] In one embodiment, the vacuum belt filter 6 generally adopts a five-stage vacuum belt filter, including a mother liquor zone, a four-stage elution zone and a draining zone. The liquid outlet of the mother liquor zone corresponds to the concentrated brine outlet, the liquid outlet of the first-stage elution zone corresponds to the dilute brine outlet, and the draining zone corresponds to the filter cake ash outlet.
[0018] The utility model discloses a slurry treatment system in the treatment of salt slag aluminum ash, and further comprises a barium chloride storage tank 10, wherein the liquid outlet of the barium chloride storage tank 10 is connected to the barium chloride inlet at the top of the concentrated brine precipitation tank 7 (a new inlet may be opened on the concentrated brine precipitation tank 7). Further, a metering pump is arranged on the pipeline connecting the liquid outlet of the barium chloride storage tank 10 to the barium chloride inlet at the top of the concentrated brine precipitation tank 7, and a liquid level gauge is arranged on each concentrated brine precipitation tank 7, and the sulfate content is sampled and analyzed at the net brine outlet on the side of each concentrated brine precipitation tank 7, and the liquid level gauge feeds back the height in the concentrated brine precipitation tank, and the total sulfate content is calculated according to the liquid level height and the storage tank volume, and then the demand for barium chloride in each concentrated brine precipitation tank 7 is calculated, and the barium chloride solution (with a concentration of 300 g / L) is accurately added to the concentrated brine precipitation tank 7 through the metering pump, and barium sulfate precipitate is generated with sulfate, and the precipitate is discharged together with the bottom slurry and sent to the vacuum belt filter 6, and the barium sulfate precipitate is retained in the filter cake during the filtration, so that the sulfate no longer enters the MVR evaporator 8 but enters the composite salt product.
[0019] In order to accurately calculate the sulfate content, the slurry processing system in the salt slag aluminum ash processing of the utility model further includes an air compressor 11, and the outlet of the air compressor 11 is connected to the bottom outlet of the concentrated brine precipitation tank 7. Further, for the convenience of operation, the bottom outlet pipeline of the concentrated brine precipitation tank 7 is divided into an air pipeline and a slurry pipeline, and corresponding control valves are set on the pipeline, the air pipeline is connected to the air compressor 11, and the slurry pipeline is connected to the raw material inlet of the vacuum belt filter 6. After the concentrated brine enters the concentrated brine precipitation tank 7, air is introduced into the concentrated brine precipitation tank 7 from the air pipe. After aeration and stirring for 5 minutes, the sulfate content is sampled and analyzed from the clean brine outlet on the side of the concentrated brine precipitation tank 7, so that the sulfate content can be obtained more accurately; after adding the barium chloride solution to the concentrated brine precipitation tank 7, air is introduced into the concentrated brine precipitation tank 7 again, and aeration and stirring are carried out for 5 minutes to allow the sulfate and barium chloride to fully react to form barium sulfate precipitate. After sedimentation and aging for 24 hours, the pure concentrated brine is discharged from the clean brine outlet on the side of the concentrated brine precipitation tank 7, and air is introduced into the concentrated brine precipitation tank 7 again. Aeration and stirring are carried out for 5 minutes, and the barium sulfate and slurry are discharged from the slurry pipeline of the concentrated brine precipitation tank 7 and sent to the vacuum belt filter 6.
[0020] like Figure 2 As shown, the slurry treatment system is provided with three concentrated brine precipitation tanks 7, which alternately carry out processes such as the introduction of concentrated brine, the introduction of barium chloride solution, reaction, sedimentation, aging, discharge of upper clean concentrated brine, and discharge of bottom precipitated barium sulfate and slurry, so as to ensure stable and continuous production.
[0021] The utility model adds a barium chloride storage tank 10 and an air compressor 11 to the slurry treatment system, adds a barium chloride solution to the concentrated brine precipitation tank 7, and generates barium sulfate precipitate with sulfate. In addition, air is introduced into the concentrated brine precipitation tank 7 for aeration and stirring in the sampling and analysis process, the precipitation reaction process, and the slurry discharge process, so that the sulfate removal rate is higher, and finally the barium sulfate precipitate is retained in the filter cake and no longer exists in the composite salt product, thereby avoiding the high-temperature decomposition of sodium sulfate to produce sulfur dioxide in the process of using the composite salt in the rotary kiln, thereby reducing the sulfur dioxide content of the rotary kiln tail gas to 5mg / m 3 , far below the national emission standard of 50mg / m 3 .
[0022] The embodiments described above are only preferred embodiments of the present invention and are only used to explain the present invention, not to limit the scope of implementation of the present invention. For those skilled in the art, other implementation methods can certainly be easily made by replacement or modification based on the technical contents disclosed in this specification. Therefore, all changes and improvements made on the principles of the present invention should be included in the scope of the patent application of the present invention.
Claims
1. A slurry treatment system in salt slag aluminum ash treatment, comprising a batching tank (1), a reaction tank (2), a vacuum belt filter (6), a concentrated brine precipitation tank (7), a dilute brine tank (9) and an MVR evaporator (8), wherein the liquid outlet of the dilute brine tank (9) is connected to the liquid inlet of the batching tank (1), the bottom liquid outlet of the batching tank (1) is connected to the liquid inlet of the reaction tank (2), the bottom liquid outlet 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 top brine inlet of the concentrated brine precipitation tank (7), the dilute brine outlet of the vacuum belt filter (6) is connected to the liquid inlet of the dilute brine tank (9), the liquid outlet of the dilute brine tank (9) is connected to the liquid inlet of the batching tank (1), the bottom outlet of the concentrated brine precipitation tank (7) is connected to the raw material inlet of the vacuum belt filter (6), and the side clean brine outlet of the concentrated brine precipitation tank (7) is connected to the MVR evaporator (8), characterized in that: It also comprises a barium chloride storage tank (10) and an air compressor (11), wherein the liquid outlet of the barium chloride storage tank (10) is connected to the barium chloride inlet at the top of the concentrated brine precipitation tank (7), and the outlet of the air compressor (11) is connected to the bottom outlet of the concentrated brine precipitation tank (7).
2. The slurry processing system in salt slag aluminum ash processing according to claim 1 is characterized in that: A metering pump is provided on a pipeline connecting the liquid outlet of the barium chloride storage tank (10) to the barium chloride inlet at the top of the concentrated brine precipitation tank (7).
3. The slurry processing system in salt slag aluminum ash processing according to claim 1 is characterized in that: The bottom outlet pipe of the concentrated brine precipitation tank (7) is divided into an air pipe and a slurry pipe. The air pipe is connected to the air compressor (11), and the slurry pipe is connected to the raw material inlet of the vacuum belt filter (6).
4. The slurry processing system in salt slag aluminum ash processing according to claim 1 is characterized in that: The concentrated brine precipitation tank (7) is provided with a liquid level meter.