Method and device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud

Abstract

The present invention belongs to the technical field of red mud treatment, and specifically relates to a method and device for preparing aluminum chloride solution by leaching red mud at normal pressure, comprising aeration dealkalization equipment for removing sodium from the red mud, the aeration dealkalization equipment comprising a dealkalization tower and an air supply pipe, and also comprising a countercurrent reaction mechanism, the countercurrent reaction mechanism being used to control the countercurrent reaction of red mud slurry and carbon dioxide gas flow. The present invention provides a countercurrent reaction mechanism, and when the red mud is dealkalized, the red mud is controlled to move from bottom to top, while the flue gas and water move from top to bottom, so that the salt content in the upper reaction chamber decreases step by step, the carbon dioxide content increases step by step, and the soluble alkali content decreases step by step. During the upward movement of the red mud, the soluble alkali is separated step by step. After eliminating the obstruction of the soluble alkali to the red mud carbon ring, it is convenient to use the carbon dioxide with gradually increasing concentration to carry out a carbonization reaction on the insoluble alkali in the red mud, and finally form it in the topmost reaction chamber.

Description

Technical Field

[0001] The invention belongs to the technical field of red mud treatment, and specifically relates to a method and a device for preparing aluminum chloride solution by leaching red mud at normal pressure. Background Art

[0002] Red mud is a highly alkaline industrial waste residue produced during the Bayer process of alumina production from bauxite. This solid waste contains large amounts of residual caustic soda (Na2O content of 8%-15%) and heavy metals such as chromium and lead. Long-term storage of this solid waste can lead to secondary environmental problems such as soil sodification and abnormally elevated groundwater pH levels in the surrounding areas. Its safe disposal has become a major environmental challenge hindering the sustainable development of the industry.

[0003] The current mainstream red mud resource utilization technology focuses on blast furnace smelting to produce cast iron and slag products for construction. However, metallurgical industry technical specifications clearly state that because the phosphorus content (0.3%-0.8%) and sodium content in red mud far exceed the standard values for ironmaking raw materials, it can easily lead to increased lining erosion during the smelting process (sodium erosion coefficient K>1.5), resulting in strict restrictions on the industrial application of this technology. Another technical approach proposed in the field of environmental engineering is to use the alumina component (20%-30% by mass) in red mud to achieve selective leaching of aluminum chloride in an acidic medium, and then prepare a high-efficiency flocculant through hydrolysis and polymerization. This provides a new approach to the high-value utilization of red mud.

[0004] However, experimental studies have revealed that the dense aluminosilicate coating (thickness of about 50-200 nm) on the surface of red mud particles significantly hinders the flow of H + Diffusion mass transfer and thermodynamic analysis show that the theoretical value of aluminum leaching efficiency does not exceed 62.3%. More importantly, the multi-metal chlorides (such as FeCl3, TiCl4) in the leaching system and Al 3+ Al 3+ -Fe 3+ -Cl - The ternary complexation system triggers the precipitation of hydroxychloride, which necessitates the addition of ion exchange resin columns (exchange capacity ≥ 2.2 eq / L) and nanofiltration membrane assemblies (molecular weight cutoff 200 Da) in the subsequent separation process. Engineering economic assessment data show that this process segment directly increases operating costs by nearly 40%, becoming a key technical bottleneck restricting the industrial application of the acid leaching method.

[0005] In order to remove caustic soda from red mud, a red mud dealkalization device has been disclosed in the related art, with the publication number CN114716120A. In this scheme, a placement plate and a cleaning member slidably connected to the placement plate are provided. The placement plates are staggered from top to bottom on the inner wall of the tank body. The red mud raw material is continuously spread on multiple placement plates during the falling process, which can greatly increase the reaction contact area between the red mud raw material and the carbon dioxide gas. However, in actual application, it was found that since only the surface of the red mud slurry is in contact with carbon dioxide and the solubility of carbon dioxide in water is low, the carbonization dealkalization rate of the red mud is slow.

[0006] In view of this, the present invention proposes a method and device for preparing aluminum chloride solution by leaching red mud at normal pressure, which are used to solve the above technical problems. Summary of the Invention

[0007] In order to make up for the deficiencies of the prior art and solve the above-mentioned technical problems, the present invention proposes a method and apparatus for preparing aluminum chloride solution by leaching red mud at normal pressure.

[0008] The technical solution adopted by the present invention to solve the technical problem is as follows: the device for preparing aluminum chloride solution by leaching red mud at normal pressure of the present invention includes an aeration dealkalization device for removing sodium from the red mud, the aeration dealkalization device comprises a dealkalization tower and an air supply pipe, the dealkalization tower is a cavity-type structure, the air supply pipe is installed on the dealkalization tower, and the air supply pipe is used to transport blast furnace flue gas into the dealkalization tower;

[0009] The invention also includes a countercurrent reaction mechanism, which is installed inside the dealkalization tower and is used to control the countercurrent reaction between the red mud slurry and the carbon dioxide gas flow. The countercurrent reaction mechanism includes an aeration pipe, a liquid supply pipe, a mud pump, a liquid discharge pipe and a partition;

[0010] A plurality of partitions are fixedly installed in the inner cavity of the dealkalization tower, and the partitions divide the inner cavity of the dealkalization tower into a plurality of reaction chambers that are not connected to each other;

[0011] The dealkalization tower is provided with a liquid supply pipe, which is in conductive connection with the bottom reaction chamber and is used for conveying red mud slurry.

[0012] The dealkalization tower is equipped with multiple mud pumps, which are used to transport the red mud slurry in two adjacent reaction chambers, and the transport direction is from the lower reaction chamber to the upper reaction chamber, and the reaction chambers correspond to the mud pumps one by one;

[0013] The dealkalization tower is provided with a drain pipe, which is electrically connected to the bottom reaction chamber;

[0014] The air supply pipe extends into the topmost reaction chamber, and aeration pipes are installed on each of the partitions. The aeration pipes are used to transport the gas in the upper reaction chamber to the lower reaction chamber. The bottom end of the aeration pipe is located below the liquid level of the red mud slurry in the lower reaction chamber, and the top end of the aeration pipe is located above the liquid level of the red mud slurry in the upper reaction chamber.

[0015] Preferably, the countercurrent reaction mechanism further comprises a water supply pipe, which is installed at the top of the dealkalization tower and is used to supply pure water to the topmost reaction chamber.

[0016] Preferably, a heat exchange tube is installed in the reaction chamber at the bottom, one end of the heat exchange tube is connected to the air supply pipe, and the other end is connected to the blast furnace flue gas pumping equipment, and an exhaust pipe is installed on the dealkalization tower.

[0017] Preferably, the outer layer of the dealkalization tower is provided with a jacket, and an insulation chamber is formed between the jacket and the dealkalization tower. The exhaust pipe extends into the insulation chamber, and a gas-liquid separator is installed above the dealkalization tower. The exhaust end of the gas-liquid separator is connected to the outside world, and the discharge end of the gas-liquid separator is connected to the water supply pipe.

[0018] Preferably, the aeration tube is rotatably mounted on the partition via a bearing, the aeration tube is arranged in a trident shape, a guide tube is embedded and installed at the bottom end of the aeration tube, and the guide tube is opened along the circumferential direction of the reaction chamber.

[0019] Preferably, the partitions are all in a conical shape with the openings facing upwards, the mud pump input ends are all extended to the conical bottom of the partitions, and the mud pump output ends are all extended to above the corresponding guide pipes.

[0020] Preferably, a dehydration box is installed at the top of the dealkalization tower, a filter bag is fixedly installed in the dehydration box, the mud pump corresponding to the topmost reaction chamber has its output end extending above the filter bag, and the bottom of the dehydration box is connected to the water supply pipe.

[0021] Preferably, the dehydration box is located in the middle of the air supply pipe, and both the inner and outer sides of the filter bag are located on the air flow path.

[0022] Preferably, it also includes a magnetic separator for magnetic separation of red mud, a high-temperature reduction furnace for carbon thermal reduction of dealkalized red mud, and a reactor for acid leaching. The exhaust port of the high-temperature reduction furnace transports blast furnace flue gas to the aeration desodium equipment through a pipeline.

[0023] A method for preparing aluminum chloride solution by leaching red mud at normal pressure, the method comprising the following steps:

[0024] S1. Magnetic separation: The raw red mud is crushed and ground, then passed into a magnetic separator to obtain a magnetic-rich component and a non-magnetic component after magnetic separation;

[0025] S2, carbonization dealkalization: the magnetic-rich components obtained in S1 are mixed with water to form a red mud slurry, and the red mud slurry is passed into an aeration dealkalization device, and carbon dioxide is continuously introduced under the conditions of a pressure of 3.8-4.2 MPa and a temperature of 45-55 degrees Celsius for a carbonization reaction of 2 hours.

[0026] S3, countercurrent reaction: After the red mud slurry enters the bottom reaction chamber, it is pumped upward step by step by the mud pump, and the blast furnace flue gas and water are pumped downward step by step from the top reaction chamber to promote the red mud to be de-alkali. After the reaction is completed, it is filtered and dried to obtain de-sodium red mud.

[0027] S4, carbothermal reduction: add carbon powder to the de-sodium red mud, transfer it to a high-temperature reduction furnace and heat it to 1550-1750℃. After high-temperature carbothermal reduction for 15-120 minutes, the iron-silicon alloy phase is separated from the slag by density difference;

[0028] S5. Atmospheric pressure acid leaching: Blend the slag and HCl solution in a reactor and react at 90-105°C for 30-120 minutes. After the reaction is completed, the filtrate obtained after solid-liquid separation is aluminum chloride solution;

[0029] The mass ratio of desodiumized red mud to carbon powder in S4 is 100:8;

[0030] The liquid-to-solid ratio of the hydrochloric acid solution to the slag in S5 is 5-12 ml / g.

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. The method and apparatus for preparing aluminum chloride solution by leaching red mud at normal pressure described in the present invention, by providing a countercurrent reaction mechanism, controls the red mud to move from bottom to top during dealkalization treatment, while the flue gas and water move from top to bottom, thereby causing the salt content, carbon dioxide content, and soluble alkali content to decrease step by step in the reaction chambers located at the top to gradually decrease. On the one hand, during the upward movement of the red mud, the soluble alkali is gradually separated. After eliminating the obstruction of the soluble alkali to the red mud carbon ring, the insoluble alkali in the red mud is carbonized by the carbon dioxide with gradually increasing concentration, and finally formed in the topmost reaction chamber. On the other hand, due to the continuous water supply from the top water supply pipe, the soluble salt generated by the dealkalization reaction is gradually flushed to the bottommost reaction chamber by the flow of water to form high-salt wastewater, which is convenient for the subsequent recovery of components such as sodium carbonate therein.

[0033] 2. The method and apparatus for preparing aluminum chloride solution by leaching red mud at normal pressure described in the present invention, by providing heat exchange tubes and jackets, continuously delivers high-temperature blast furnace flue gas during the carbonization and dealkalization operation of the red mud, and utilizes the waste heat of the blast furnace flue gas to continuously heat the high-salt wastewater collected in the bottom reaction chamber, thereby returning the water component in the high-salt wastewater to the top reaction chamber in the form of steam and condensate, thereby saving water resources and concentrating the salt components. At the same time, the discharged steam, as an intermediate product, can also provide economic value to the reaction system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below with reference to the accompanying drawings.

[0035] Figure 1 It is a perspective view of the present invention;

[0036] Figure 2 This is a three-dimensional diagram of the assembly of the aeration pipe and the guide pipe;

[0037] Figure 3 It is a three-dimensional diagram of the air supply pipe and the heat exchange pipe;

[0038] Figure 4 It is a three-dimensional picture of the filter bag;

[0039] Figure 5 is a cross-sectional view of the present application;

[0040] Figure 6 yes Figure 5 A partial enlarged view of the middle A;

[0041] Figure 7 yes Figure 5 A partial enlarged view of point B in the middle;

[0042] Figure 8 is a flow chart of the method of the present invention;

[0043] In the figure: 1. dealkalization tower; 11. partition; 12. reaction chamber; 2. air supply pipe; 21. liquid supply pipe; 22. mud pump; 23. discharge pipe; 24. aeration pipe; 25. water supply pipe; 26. heat exchange pipe; 27. exhaust pipe; 28. jacket; 29. insulation chamber; 3. gas-liquid separator; 4. guide pipe; 5. dehydration box; 51. filter bag. DETAILED DESCRIPTION

[0044] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0045] like Figures 1 to 8As shown, the device for preparing aluminum chloride solution by leaching red mud at normal pressure according to the present invention includes an aeration dealkalization device for removing sodium from the red mud. The aeration dealkalization device comprises a dealkalization tower 1 and an air supply pipe 2. The dealkalization tower 1 is a cavity-type structure. The air supply pipe 2 is installed on the dealkalization tower 1. The air supply pipe 2 is used to transport blast furnace flue gas into the dealkalization tower 1. The air supply pipe 2 is made of a heat-insulating material. The blast furnace flue gas is the flue gas discharged from a high-temperature furnace, which not only contains high heat but also a high carbon dioxide content. By introducing the blast furnace flue gas into the red mud slurry, the carbon dioxide therein can be utilized to achieve dealkalization of the red mud.

[0046] It also includes a countercurrent reaction mechanism, which is installed inside the dealkalization tower 1 and is used to control the countercurrent reaction between the red mud slurry and the carbon dioxide gas flow. The countercurrent reaction mechanism includes an aeration pipe 24, a liquid supply pipe 21, a mud pump 22, a liquid discharge pipe 23 and a partition 11;

[0047] A plurality of partitions 11 are fixedly installed in the inner cavity of the dealkalization tower 1, and the partitions 11 divide the inner cavity of the dealkalization tower 1 into a plurality of reaction chambers 12 that are not connected to each other;

[0048] The dealkalization tower 1 is provided with a liquid supply pipe 21, which is electrically connected to the bottom reaction chamber 12. The liquid supply pipe 21 is used to transport red mud slurry, which is a mixture of red mud and water. In the initial state, the liquid-to-solid ratio of the red mud slurry transported in the liquid supply pipe 21 is less than 7.

[0049] The dealkalization tower 1 is provided with a drain pipe 23, which is conductively connected to the bottom reaction chamber 12. In the present invention, the drain pipe 23 and the liquid supply pipe 21 are both conductively connected to the bottom reaction chamber 12, wherein the liquid supply pipe 21 is conductively connected to the middle of the bottom reaction chamber 12, and the drain pipe 23 is installed at the bottom of the bottom reaction chamber 12 for discharging high-concentration wastewater after dealkalization. In actual application, the drain pipe 23 is initially in a closed state;

[0050] The dealkalization tower 1 is equipped with multiple mud pumps 22, which are used to transport the red mud slurry in two adjacent reaction chambers 12, and the transport direction is from the lower reaction chamber 12 to the upper reaction chamber 12. The reaction chambers 12 correspond to the mud pumps 22 one by one.

[0051] The air supply pipe 2 extends into the topmost reaction chamber 12, and an aeration pipe 24 is installed on each of the partitions 11. The aeration pipe 24 is used to transport the gas in the upper reaction chamber 12 to the lower reaction chamber 12. The bottom end of the aeration pipe 24 is located below the red mud slurry level in the lower reaction chamber 12, and the top end of the aeration pipe 24 is located above the red mud slurry level in the upper reaction chamber 12. The top end of the aeration pipe 24 is used to control the liquid level in the corresponding reaction chamber 12, and the bottom end of the aeration pipe 24 is used for aeration treatment.

[0052] The countercurrent reaction mechanism also includes a water supply pipe 25, which is installed at the top of the dealkalization tower 1. The water supply pipe 25 is used to transport pure water into the top reaction chamber 12. The pure water recorded here is water with low impurity content that is not mixed with red mud.

[0053] When red mud is treated, in order to reduce the hindrance of the caustic soda components contained in the red mud to subsequent treatment, the red mud needs to be dealkalized. During the dealkalization treatment, the carbon dioxide dealkalization method causes the two wastes, blast furnace flue gas and red mud slurry, to interact with each other, which can not only purify the blast furnace flue gas and utilize the waste heat in the blast furnace flue gas, but also promote the conversion of caustic soda in the red mud slurry into soluble salts. When using carbon dioxide to dealkalize red mud, in order to improve the reaction efficiency of carbon dioxide and red mud, a countercurrent reaction mechanism is provided in the present invention.

[0054] Specifically, in the red mud carbonization dealkalization treatment, the staff stably transports the red mud slurry to the reaction chamber 12 at the bottom of the dealkalization tower 1 through the liquid supply pipe 21, and mixes it with the aqueous solution already in the reaction chamber 12. At this time, a large amount of soluble caustic soda in the red mud slurry is directly dissolved in the water, and the solid red mud settles to the bottom of the reaction chamber 12. The mud pump 22 installed on the dealkalization tower 1 continuously transports the red mud slurry with a higher solid content at the bottom of the reaction chamber 12 to the upper-level reaction chamber 12. The red mud slurry at the bottom of the upper reaction chamber 12 is pumped to the upper layer by the corresponding mud pump 22. When the red mud slurry reaches the top reaction chamber 12 and the liquid level is flush with the top of the aeration pipe 24, the red mud slurry in the top reaction chamber 12 flows downward along the multiple aeration pipes 24 in sequence. In this process, the red mud slurry is diluted multiple times, resulting in rapid separation of the soluble alkali in the red mud slurry. At the same time, the blast furnace flue gas and pure water are respectively discharged through the air supply pipe 2 and the water supply pipe. 25 is transported to the top reaction chamber 12, and as the blast furnace flue gas and pure water are continuously fed in, the air pressure in the top reaction chamber 12 increases and the liquid level rises. Under the guidance of the aeration pipe 24, the flue gas flows along the aeration pipe 24 and, under the action of the air pressure, displaces the liquid inside the aeration pipe 24 and aerates the lower reaction chamber 12. As the air pressure in the lower reaction chamber 12 increases, the flue gas flows into the lower reaction chamber 12 along the multiple aeration pipes 24 arranged in sequence. During the process, the flue gas contacts the red mud slurry, causing the carbon dioxide in the flue gas to carbonize and dealkalize the red mud. At the same time, the carbon dioxide is also dissolved in water and is further used to carbonize and dealkalize the red mud. In addition, since the water supply pipe 25 continuously supplies water, the aqueous solution in the reaction chamber 12 is diluted, causing the soluble salts generated by dealkalization to gradually flow into the lower reaction chamber 12. Therefore, a red mud slurry with low salt and alkali content is finally formed in the top reaction chamber 12. After subsequent separation, the dealkalized red mud can be obtained.

[0055] The present invention sets a countercurrent reaction mechanism. When the red mud is dealkalized, the red mud is controlled to move from bottom to top, while the flue gas and water move from top to bottom. Therefore, the salt content in the upper reaction chamber 12 decreases step by step, the carbon dioxide content increases step by step, and the soluble alkali content decreases step by step. On the one hand, during the upward movement of the red mud, the soluble alkali is separated step by step. After eliminating the obstruction of the soluble alkali to the red mud carbon ring, it is convenient to use the carbon dioxide with increasing concentration to carbonize the insoluble alkali in the red mud, and finally form it in the topmost reaction chamber 12. On the other hand, due to the continuous water supply of the top water supply pipe 25, the soluble salt generated by the dealkalization reaction is gradually flushed to the bottommost reaction chamber 12 by the flow of water to form high-salt wastewater, which is convenient for the subsequent recovery of components such as sodium carbonate therein.

[0056] As a preferred embodiment of the present invention, a heat exchange tube 26 is installed in the reaction chamber 12 at the bottom end, one end of the heat exchange tube 26 is conductively connected to the air supply pipe 2, and the other end is conductively connected to the blast furnace flue gas pumping equipment, and an exhaust pipe 27 is installed on the dealkalization tower 1.

[0057] The outer layer of the dealkalization tower 1 is provided with a jacket 28, and an insulation chamber 29 is formed between the jacket 28 and the dealkalization tower 1. The exhaust pipe 27 extends into the insulation chamber 29. A gas-liquid separator 3 is installed above the dealkalization tower 1. The exhaust end of the gas-liquid separator 3 is connected to the outside world, and the discharge end of the gas-liquid separator 3 is connected to the water supply pipe 25.

[0058] During the continuous reaction, since the temperature of the initial blast furnace flue gas is relatively high, in order to make the temperature in the multiple reaction chambers 12 more uniform, in the present invention, the blast furnace flue gas is first transported to the heat exchange tube 26 in the bottom reaction chamber 12, and after heat exchange with the high-salt wastewater in the bottom reaction chamber 12, the flue gas with reduced temperature enters the air supply pipe 2, and flows step by step along the reaction chamber 12, is washed with water, and finally flows into the bottom reaction chamber 12. With the continuous transportation of blast furnace flue gas, the high-salt wastewater in the top reaction chamber 12 gradually generates steam, and the steam mixed with the gas flows along the exhaust pipe 27. In the present invention, the exhaust pipe has at least two openings, one of which leads to the jacket 28, so that the steam and the air flow enter the jacket 28 together. When the steam rises in the insulation chamber 29, it can cooperate with the flow of the blast furnace flue gas to The steam and the washed blast furnace flue gas enter the gas-liquid separator 3, and the steam condenses into water under the action of the gas-liquid separator 3, and flows into the reaction chamber 12 through the water supply pipe 25, which is used to flush the soluble salt to the bottom reaction chamber 12, and the washed blast furnace flue gas is discharged to the outside through the gas-liquid separator 3. After the other opening of the exhaust pipe 27 is opened, the discharged steam and the washed blast furnace flue gas are collected for utilization, and since the exhaust pipe 27 can discharge a part of the steam, the total amount of red mud slurry in the dealkalization tower 1 is reduced, so as to continuously pump new red mud slurry into the dealkalization tower 1, and after a period of continuous reaction, the pumping of new red mud slurry is stopped. In the continuous blast furnace flue gas heat exchange process, the high-salt wastewater in the bottom reaction chamber 12 is gradually concentrated, and finally the drain pipe 23 is opened to discharge the high-salt wastewater.

[0059] The present invention provides heat exchange tubes 26 and jackets 28. During the carbonization and dealkalization operation of red mud, high-temperature blast furnace flue gas is continuously transported and the waste heat of the blast furnace flue gas is utilized to continuously heat the high-salt wastewater gathered in the bottom reaction chamber 12, thereby returning the water components in the high-salt wastewater to the top reaction chamber 12 in the form of steam and condensed water. This can save the use of water resources and gather the salt components. At the same time, the discharged steam, as an intermediate product, can also provide economic value for the reaction system.

[0060] As a preferred embodiment of the present invention, the aeration tube 24 is rotatably mounted on the partition 11 through a bearing. The aeration tube 24 is arranged in a trident shape. A guide tube 4 is embedded in the bottom end of the aeration tube 24. The guide tube 4 is opened along the circumferential direction of the reaction chamber 12. In the present invention, the openings on the guide tube 4 are evenly distributed, and an overflow valve is installed in the opening to cooperate with the water pressure to control the air pressure in the reaction chamber 12.

[0061] The partitions 11 are all tapered with the opening facing upwards, the input ends of the mud pumps 22 are all extended to the tapered bottom of the partitions 11 , and the output ends of the mud pumps 22 are all extended to above the corresponding guide pipes 4 .

[0062] During the step-by-step aeration dealkalization, the blast furnace flue gas enters the next-stage reaction chamber 12 from the top reaction chamber 12 through the aeration pipes 24 arranged in sequence. During this process, under the action of air pressure, the flue gas enters the aeration pipe 24, displaces the solution in the aeration pipe 24 and the guide pipe 4, and is ejected outward from the opening on the side wall of the guide pipe 4. Since the guide pipe 4 is open along the circumferential direction of the reaction chamber 12, the guide pipe 4 and the aeration pipe 24 rotate under the reaction force formed by the airflow injection. On the one hand, the rotation makes the aeration operation of the red mud slurry in the reaction chamber 12 more uniform, which facilitates the reaction of carbon dioxide with the alkali components in the red mud. On the other hand, the continuous unidirectional rotation rotates the solution in the reaction chamber 12, thereby allowing the red mud particles settled at the bottom of the reaction chamber 12 to converge to the center of the partition 11, making it easier for the mud pump 22 to extract the red mud particles, so that the red mud particles gradually converge to the topmost reaction chamber 12.

[0063] As a preferred embodiment of the present invention, a dehydration box 5 is installed at the top of the dealkalization tower 1, and a filter bag 51 is fixedly installed in the dehydration box 5. The mud pump 22 corresponding to the topmost reaction chamber 12 has its output end extending above the filter bag 51, and the bottom of the dehydration box 5 is connected to the water supply pipe 25.

[0064] The dehydration box 5 is located in the middle of the air supply pipe 2, and both the inner and outer sides of the filter bag 51 are located on the air flow path.

[0065] In order to separate the dealkalized red mud particles from water, after the red mud particles are pumped to the top reaction chamber 12 by the mud pump 22, under the action of gravity, the red mud particles gradually deposit on the partition 11 and are extracted by the mud pump 22 corresponding to the top reaction chamber 12 and pumped into the filter bag 51 in the dehydration box 5. Under the filtering action of the filter bag 51, the red mud particles are separated from the water, wherein the aqueous solution flows back to the top reaction chamber 12 through the water supply pipe 25, while the red mud particles remain in the filter bag 51. At the same time, after the blast furnace flue gas enters the air supply pipe 2, it enters the dehydration box 5 along the air supply pipe 2. At this time, the flue gas is in a high temperature and dry state. The flue gas contacts the red mud, so that the moisture contained in the red mud particles gradually decreases, and the flue gas carrying water vapor continues to be transported along the air supply pipe 2 to the top reaction chamber 12, further enhancing the convenience of red mud treatment.

[0066] As a preferred embodiment of the present invention, it also includes a magnetic separator for magnetic separation of red mud, a high-temperature reduction furnace for carbon thermal reduction of dealkalized red mud, and a reactor for acid leaching. The exhaust port of the high-temperature reduction furnace transports blast furnace flue gas to the aeration desodium equipment through a pipeline. The high-temperature reduction furnace is combined with the aeration dealkalization equipment to effectively reduce the total amount of waste ultimately discharged from the reaction system.

[0067] A method for preparing aluminum chloride solution by leaching red mud at normal pressure, the method comprising the following steps:

[0068] S1. Magnetic separation: The raw red mud is crushed and ground, then passed into a magnetic separator to obtain a magnetic-rich component and a non-magnetic component after magnetic separation;

[0069] S2, carbonization dealkalization: the magnetic-rich components obtained in S1 are mixed with water to form a red mud slurry, and the red mud slurry is passed into an aeration dealkalization device, and carbon dioxide is continuously introduced under the conditions of a pressure of 3.8-4.2 MPa and a temperature of 45-55 degrees Celsius for a carbonization reaction of 2 hours.

[0070] S3, countercurrent reaction: After the red mud slurry enters the bottom reaction chamber 12, it is pumped upward step by step by the mud pump 22, and the blast furnace flue gas and water are pumped downward step by step from the top reaction chamber 12 to promote the dealkalization of the red mud. After the reaction is completed, it is filtered and dried to obtain desodium red mud;

[0071] S4, carbothermal reduction: add carbon powder to the de-sodium red mud, transfer it to a high-temperature reduction furnace and heat it to 1550-1750℃. After high-temperature carbothermal reduction for 15-120 minutes, the iron-silicon alloy phase is separated from the slag by density difference;

[0072] S5. Acid leaching at normal pressure: Blend the slag and HCl solution in a reactor and react at 90-105°C for 30-120 minutes. After the reaction is completed, the filtrate obtained after solid-liquid separation is aluminum chloride solution.

[0073] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for preparing aluminum chloride solution by leaching red mud at normal pressure, comprising an aeration dealkalization device for removing sodium from red mud, the aeration dealkalization device comprising a dealkalization tower (1) and an air supply pipe (2), the dealkalization tower (1) being a cavity-type structure, the air supply pipe (2) being installed on the dealkalization tower (1), and the air supply pipe (2) being used to transport blast furnace flue gas into the dealkalization tower (1); Its characteristics are: It also includes a countercurrent reaction mechanism, which is installed inside the dealkalization tower (1) and is used to control the countercurrent reaction between the red mud slurry and the carbon dioxide gas flow. The countercurrent reaction mechanism includes an aeration pipe (24), a liquid supply pipe (21), a mud pump (22), a liquid discharge pipe (23) and a partition (11); A plurality of partitions (11) are fixedly installed in the inner cavity of the dealkalization tower (1), and the partitions (11) divide the inner cavity of the dealkalization tower (1) into a plurality of reaction chambers (12) that are not connected to each other; A liquid supply pipe (21) is installed on the dealkalization tower (1), and the liquid supply pipe (21) is conductively connected to the bottom reaction chamber (12). The liquid supply pipe (21) is used to transport red mud slurry; A plurality of mud pumps (22) are installed on the dealkalization tower (1), and the mud pumps (22) are used to transport red mud slurry in two adjacent reaction chambers (12), and the transport direction is from the lower reaction chamber (12) to the upper reaction chamber (12), and the reaction chambers (12) correspond to the mud pumps (22) one by one; A drain pipe (23) is installed on the dealkalization tower (1), and the drain pipe (23) is conductively connected to the bottom reaction chamber (12); The air supply pipe (2) extends into the topmost reaction chamber (12), and an aeration pipe (24) is installed on each of the partitions (11). The aeration pipe (24) is used to transport the gas in the upper reaction chamber (12) to the lower reaction chamber (12), and the bottom end of the aeration pipe (24) is located below the liquid level of the red mud slurry in the lower reaction chamber (12), and the top end of the aeration pipe (24) is located above the liquid level of the red mud slurry in the upper reaction chamber (12).

2. The device for preparing aluminum chloride solution by leaching red mud at normal pressure according to claim 1, characterized in that: The countercurrent reaction mechanism further comprises a water supply pipe (25), which is installed at the top of the dealkalization tower (1). The water supply pipe (25) is used to supply pure water to the topmost reaction chamber (12).

3. The device for preparing aluminum chloride solution by leaching red mud at normal pressure according to claim 2, characterized in that: A heat exchange tube (26) is installed in the reaction chamber (12) at the bottom end. One end of the heat exchange tube (26) is connected to the air supply pipe (2) and the other end is connected to the blast furnace flue gas pumping equipment. An exhaust pipe (27) is installed on the dealkalization tower (1).

4. The device for preparing aluminum chloride solution by leaching red mud at normal pressure according to claim 3, characterized in that: The outer layer of the dealkalization tower (1) is provided with a jacket (28), and a heat preservation chamber (29) is formed between the jacket (28) and the dealkalization tower (1). The exhaust pipe (27) extends into the heat preservation chamber (29). A gas-liquid separator (3) is installed above the dealkalization tower (1), and the exhaust end of the gas-liquid separator (3) is conductively connected to the outside world, and the discharge end of the gas-liquid separator (3) is conductively connected to the water supply pipe (25).

5. The device for preparing aluminum chloride solution by leaching red mud at normal pressure according to claim 2 or 4, characterized in that: The aeration tube (24) is rotatably mounted on the partition (11) via a bearing. The aeration tube (24) is arranged in a trident shape. A guide tube (4) is embedded and mounted at the bottom end of the aeration tube (24). The guide tube (4) is opened along the circumferential direction of the reaction chamber (12).

6. The device for preparing aluminum chloride solution by leaching red mud at normal pressure according to claim 5, characterized in that: The partitions (11) are all arranged in a conical shape with the opening facing upwards, the input ends of the mud pumps (22) are all extended to the conical bottom of the partitions (11), and the output ends of the mud pumps (22) are all extended to the top of the corresponding guide pipes (4).

7. The device for preparing aluminum chloride solution by leaching red mud at normal pressure according to claim 2 or 6, characterized in that: A dehydration box (5) is installed at the top of the dealkalization tower (1), and a filter bag (51) is fixedly installed in the dehydration box (5). The mud pump (22) corresponding to the topmost reaction chamber (12) has its output end extended above the filter bag (51), and the bottom of the dehydration box (5) is conductively connected to the water supply pipe (25).

8. The device for preparing aluminum chloride solution by leaching red mud at normal pressure according to claim 7, characterized in that: The dehydration box (5) is located in the middle of the air supply pipe (2), and both the inner and outer sides of the filter bag (51) are located on the air flow path.

9. The device for preparing aluminum chloride solution by leaching red mud at normal pressure according to claim 8, characterized in that: It also includes a magnetic separator for magnetic separation of red mud, a high-temperature reduction furnace for carbon thermal reduction of dealkalized red mud, and a reactor for acid leaching. The exhaust port of the high-temperature reduction furnace transports blast furnace flue gas to the aeration desodium equipment through a pipeline.

10. A method for preparing aluminum chloride solution by leaching red mud at normal pressure, characterized in that: The method uses the apparatus for preparing aluminum chloride solution by leaching red mud at normal pressure as described in claim 9, and the method comprises the following steps: S1. Magnetic separation: The raw red mud is crushed and ground, then passed into a magnetic separator to obtain a magnetic-rich component and a non-magnetic component after magnetic separation; S2, carbonization dealkalization: the magnetic-rich components obtained in S1 are mixed with water to form a red mud slurry, and the red mud slurry is passed into an aeration dealkalization device, and carbon dioxide is continuously introduced under the conditions of a pressure of 3.8-4.2 MPa and a temperature of 45-55 degrees Celsius for a carbonization reaction of 2 hours. S3, countercurrent reaction: After the red mud slurry enters the bottom reaction chamber (12), it is pumped upward step by step through the mud pump (22), and the blast furnace flue gas and water are pumped downward step by step from the top reaction chamber (12), thereby promoting the red mud to be de-alkali. After the reaction is completed, the red mud is filtered and dried to obtain de-sodium red mud. S4, carbothermal reduction: add carbon powder to the de-sodium red mud, transfer it to a high-temperature reduction furnace and heat it to 1550-1750℃. After high-temperature carbothermal reduction for 15-120 minutes, the iron-silicon alloy phase is separated from the slag by density difference; S5. Acid leaching at normal pressure: Blend the slag and HCl solution in a reactor and react at 90-105°C for 30-120 minutes. After the reaction is completed, the filtrate obtained after solid-liquid separation is aluminum chloride solution; The mass ratio of desodiumized red mud to carbon powder in S4 is 100:8; The liquid-to-solid ratio of the hydrochloric acid solution to the slag in S5 is 5-12 ml / g.

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