Method and device for preparing aluminum chloride solution by leaching red mud at normal pressure

Abstract

The invention belongs to the technical field of red mud treatment, and particularly relates to a method and device for preparing an aluminum chloride solution through normal-pressure leaching of red mud, the device comprises aeration dealkalization equipment for removing sodium in the red mud, the aeration dealkalization equipment comprises a dealkalization tower and an air supply pipe, and the device further comprises a countercurrent reaction mechanism, the countercurrent reaction mechanism is used for controlling the countercurrent reaction of red mud slurry and carbon dioxide airflow, and the countercurrent reaction mechanism is arranged, so that when the red mud is subjected to dealkalization treatment, the red mud is controlled to move from bottom to top, and flue gas and water move from top to bottom; therefore, the salt content, the carbon dioxide content and the soluble alkali content in the reaction cavity which is closer to the upper part are gradually reduced, the soluble alkali is gradually separated in the upward movement process of the red mud, and the red mud can be separated after the obstruction of the soluble alkali to the carbon ring of the red mud is eliminated. Carbon dioxide with gradually increased concentration can be conveniently used for carrying out carbonization reaction on insoluble alkali in the red mud, and finally the insoluble alkali is formed in the reaction cavity at the topmost end.

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 when bauxite is leached through the Bayer process to produce alumina. This solid waste contains a large amount of residual caustic soda (Na2O content reaches 8%-15%) and heavy metal elements such as Cr and Pb. Long-term storage of this solid waste can easily cause secondary environmental problems such as sodiumization of the soil around the storage yard and abnormal increase in the pH value of groundwater. Its safe disposal has become a major environmental challenge restricting the sustainable development of the industry.

[0003] The current mainstream red mud resource technology route focuses on blast furnace smelting to produce cast iron and slag products for construction. However, the technical specifications of the metallurgical industry clearly point out that since the P content (0.3%-0.8%) and sodium content in red mud far exceed the standard values ​​of ironmaking raw materials, it is easy to cause aggravated lining erosion during the smelting process (sodium erosion coefficient K>1.5), resulting in strict restrictions on the industrial application of this technology route. Another technical route proposed in the field of environmental engineering is to use the alumina component (mass fraction 20%-30%) in red mud to achieve selective leaching of aluminum chloride in an acidic medium, and then prepare high-efficiency flocculants through hydrolysis and polymerization reactions, which provides a new idea for 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 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 chloride (such as FeCl3, TiCl4) and Al in the leaching system 3+ The Al 3+ -Fe 3+ -Cl - The ternary complex system will induce the precipitation of hydroxychloride. This phenomenon requires the addition of ion exchange resin columns (exchange capacity ≥ 2.2eq / L) and nanofiltration membrane components (molecular weight cutoff 200Da) in the subsequent separation process. Engineering economic evaluation data show that this process segment directly increases operating costs by nearly 40%, becoming a key technical bottleneck restricting the industrial application of acid leaching.

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

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

[0007] To make up for the deficiencies of the prior art and solve the above technical problems, the present invention proposes a method and device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud.

[0008] The technical solution adopted by the present invention to solve its technical problems is as follows: A device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud according to the present invention includes an aeration de-alkalization device for removing sodium from red mud. The aeration de-alkalization device consists of a de-alkalization tower and a gas supply pipe. The de-alkalization tower is a cavity-type structure, and the gas supply pipe is installed on the de-alkalization tower. The gas supply pipe is used to transport blast furnace gas into the de-alkalization tower; It further includes a countercurrent reaction mechanism installed inside the de-alkalization tower. The countercurrent reaction mechanism is used to control the countercurrent reaction between the red mud slurry and the carbon dioxide gas stream. The countercurrent reaction mechanism includes an air supply pipe, a liquid supply pipe, a slurry pump, a drain pipe, and a partition; A plurality of partitions are fixedly installed in the inner cavity of the de-alkalization tower. The partitions divide the inner cavity of the de-alkalization tower into a plurality of non-communicating reaction chambers; A liquid supply pipe is installed on the de-alkalization tower. The liquid supply pipe is connected to the bottommost reaction chamber in a communicating manner. The liquid supply pipe is used to transport the red mud slurry; A plurality of slurry pumps are installed on the de-alkalization tower. The slurry pumps are used to transport the red mud slurry in adjacent two reaction chambers, and the transport direction is from the lower reaction chamber to the upper reaction chamber. The reaction chambers correspond to the slurry pumps one by one; A drain pipe is installed on the de-alkalization tower. The drain pipe is connected to the bottommost reaction chamber in a communicating manner; The gas supply pipe extends into the topmost reaction chamber. An air supply pipe is installed on each partition. The air supply pipe is used to transport the gas in the upper reaction chamber to the lower reaction chamber. The bottom end of the air supply pipe is located below the liquid level of the red mud slurry in the lower reaction chamber, and the top end of the air supply pipe is located above the liquid level of the red mud slurry in the upper reaction chamber.

[0009] Preferably, the countercurrent reaction mechanism further includes a water supply pipe installed at the top of the dealkalization tower for delivering pure water to the topmost reaction chamber.

[0010] Preferably, a heat exchange pipe is installed in the lowermost reaction chamber. One end of the heat exchange pipe is connected to the gas supply pipe in a conducting manner, and the other end is connected to the blast furnace gas pumping equipment in a conducting manner. An exhaust pipe is installed on the dealkalization tower.

[0011] Preferably, a jacket is sleeved outside the dealkalization tower. A heat preservation chamber is formed between the jacket and the dealkalization tower. The exhaust pipe extends into the heat preservation chamber. A gas-liquid separator is installed above the dealkalization tower. The exhaust end of the gas-liquid separator is connected to the outside in a conducting manner, and the liquid discharge end of the gas-liquid separator is connected to the water supply pipe in a conducting manner.

[0012] Preferably, the aeration pipe is rotatably installed on the partition board through a bearing. The aeration pipe is arranged in a three-pronged shape. A guide pipe is inlaid and installed at the bottom end of the aeration pipe. The guide pipe is provided with openings along the circumferential direction of the reaction chamber.

[0013] Preferably, the partition boards are all arranged in a conical shape with the openings facing upward. The input ends of the slurry pumps all extend to the conical bottom of the partition boards, and the output ends of the slurry pumps all extend above the corresponding guide pipes.

[0014] Preferably, a dewatering tank is installed at the top of the dealkalization tower. A filter bag is fixedly installed in the dewatering tank. The output end of the slurry pump corresponding to the topmost reaction chamber extends above the filter bag. The bottom of the dewatering tank is connected to the water supply pipe in a conducting manner.

[0015] Preferably, the dewatering tank is located in the middle of the gas supply pipe, and both the inner and outer sides of the filter bag are located on the air flow path.

[0016] Preferably, it further includes a magnetic separator for magnetic separation of red mud, a high-temperature reduction furnace for carbothermal reduction of dealkalized red mud, and a reaction kettle for acid leaching. The flue gas outlet of the high-temperature reduction furnace delivers blast furnace gas to the aeration de-sodium equipment through a pipeline.

[0017] A method for preparing aluminum chloride solution by atmospheric pressure leaching of red mud, the method comprising the following steps: S1. Magnetic separation: After the original red mud is crushed and ground, it is fed into the magnetic separator, and after magnetic separation, a ferromagnetic component and a non-magnetic component are obtained; S2. Carbonization dealkalization: The ferromagnetic component obtained in S1 is mixed with water to form a red mud slurry, and the red mud slurry is fed into the aeration dealkalization equipment. Carbon dioxide is continuously introduced under the conditions of a pressure of 3.8 - 4.2 Mpa and a temperature of 45 - 55 °C, and a carbonization reaction occurs for 2H. S3. Countercurrent reaction: After the red mud slurry enters the bottommost reaction chamber, it is pumped upward step by step by the mud pump, while the blast furnace flue gas and water move downward step by step from the topmost reaction chamber, promoting the dealkalization of the red mud. After the reaction, it is filtered and dried to obtain sodium-depleted red mud. S4. Carbothermal reduction: Add carbon powder to the sodium-depleted red mud and transfer it to a high-temperature reduction furnace for heating to 1550 - 1750 °C. After 15 - 120 minutes of high-temperature carbothermal reduction, the ferro-silicon alloy phase and the slag are separated by density difference. S5. Atmospheric pressure acid leaching: Mix the slag and HCL solution in a reaction kettle and react at 90 - 105 °C for 30 - 120 minutes. After the reaction, after solid-liquid separation, the filtrate obtained is the aluminum chloride solution. Among them, in S4, the mass ratio of the sodium-depleted red mud to the carbon powder is 100:8. Among them, in S5, the liquid-solid ratio of the hydrochloric acid solution to the slag is 5 - 12 ml / g.

[0018] The beneficial effects of the present invention are as follows: 1. For the method and device for preparing aluminum chloride solution by leaching red mud under atmospheric pressure according to the present invention, by setting up a countercurrent reaction mechanism, when dealkalizing the red mud, 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 chambers gradually decreases, the carbon dioxide content gradually increases, and the soluble alkali content gradually decreases. On the one hand, during the upward movement of the red mud, the soluble alkali is gradually removed. After eliminating the hindrance of the soluble alkali to the carbon cycle of the red mud, it is convenient to use the gradually increasing concentration of carbon dioxide to carry out carbonization reaction on the insoluble alkali in the red mud, and finally it is formed in the topmost reaction chamber. On the other hand, due to the continuous water supply of the top water supply pipe, using the flow of water, the soluble salts generated by the dealkalization reaction are gradually washed to the bottommost reaction chamber to form high-salt wastewater, which is convenient for subsequent recovery of components such as sodium carbonate in it.

[0019] 2. For the method and device for preparing aluminum chloride solution by leaching red mud under atmospheric pressure according to the present invention, by setting up heat exchange tubes and jackets, during the carbonization and dealkalization operation of the red mud, with the continuous supply of high-temperature blast furnace flue gas, using the waste heat of the blast furnace flue gas, the high-salt wastewater converged in the bottommost reaction chamber is continuously heated. Then, the water component in the high-salt wastewater returns to the topmost reaction chamber in the form of steam and condensed water. This can not only save the use of water resources, but also converge the salt components. At the same time, the discharged steam, as an intermediate product, can also provide economic value for the reaction system. Brief Description of the Drawings

[0020] The present invention will be further described below with reference to the drawings.

[0021] Figure 1 is the three-dimensional view of the present invention; Figure 2 It is a three-dimensional assembly drawing of the aeration pipe and the guide pipe; Figure 3 It is a three-dimensional drawing of the air supply pipe and the heat exchange pipe; Figure 4 It is a three-dimensional drawing of the filter bag; Figure 5 It is a sectional view of the present application; Figure 6 It is Figure 5 The partial enlarged view at position A in Figure 7 It is Figure 5 The partial enlarged view at position B in Figure 8 It is the method flow chart of the present invention; In the figure: 1, dealkalization tower; 11, partition board; 12, reaction chamber; 2, air supply pipe; 21, liquid supply pipe; 22, slurry pump; 23, liquid discharge pipe; 24, aeration pipe; 25, water supply pipe; 26, heat exchange pipe; 27, exhaust pipe; 28, jacket; 29, heat preservation chamber; 3, gas-liquid separator; 4, guide pipe; 5, dewatering tank; 51, filter bag. Specific embodiments

[0022] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0023] As Figures 1 to 8 shown, an apparatus for preparing aluminum chloride solution by atmospheric pressure leaching of red mud according to the present invention includes an aeration dealkalization device for desodium of red mud. The aeration dealkalization device consists of a dealkalization tower 1 and an air supply pipe 2. The dealkalization tower 1 is a cavity-type structure body. The air supply pipe 2 is installed on the dealkalization tower 1. The air supply pipe 2 is used to convey blast furnace gas into the dealkalization tower 1. The air supply pipe 2 is made of heat preservation material. The blast furnace gas is the gas discharged from a high-temperature furnace, which not only contains high heat but also has a relatively high carbon dioxide content. When it is introduced into the red mud slurry, the carbon dioxide in it can be used to realize the dealkalization treatment of red mud; It further includes a countercurrent reaction mechanism, which is installed inside the dealkalization tower 1 and is used to control the countercurrent reaction of the red mud slurry and the carbon dioxide gas stream. The countercurrent reaction mechanism includes an aeration pipe 24, a liquid supply pipe 21, a slurry pump 22, a liquid discharge pipe 23 and a partition board 11; A plurality of partition boards 11 are fixedly installed in the inner cavity of the dealkalization tower 1, and the partition boards 11 divide the inner cavity of the dealkalization tower 1 into a plurality of non-connecting reaction chambers 12; A liquid supply pipe 21 is installed on the de-alkalization tower 1. The liquid supply pipe 21 is connected in a conducting manner to the lowermost reaction chamber 12. The liquid supply pipe 21 is used to transport red mud slurry, and the red mud slurry is a mixture of red mud and water. In the initial state, the liquid-solid ratio of the red mud slurry transported in the liquid supply pipe 21 is less than 7; A drain pipe 23 is installed on the de-alkalization tower 1. The drain pipe 23 is connected in a conducting manner to the lowermost reaction chamber 12. In the present invention, both the drain pipe 23 and the liquid supply pipe 21 are connected in a conducting manner to the lowermost reaction chamber 12. Among them, the liquid supply pipe 21 is connected in the middle of the lowermost reaction chamber 12, while the drain pipe 23 is installed at the bottom of the lowermost reaction chamber 12 and is used to discharge the high-concentration wastewater after de-alkalization. In actual application, the drain pipe 23 is in a closed state in the initial state; A plurality of slurry pumps 22 are installed on the de-alkalization tower 1. The slurry pumps 22 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 slurry pumps 22 one by one; The air supply pipe 2 extends into the uppermost reaction chamber 12. An air diffuser pipe 24 is installed on each partition plate 11. The air diffuser 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 air diffuser 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 air diffuser pipe 24 is located above the liquid level of the red mud slurry in the upper reaction chamber 12. The top end of the air diffuser pipe 24 is used to control the liquid level height in the corresponding reaction chamber 12, and the bottom end of the air diffuser pipe 24 is used for aeration treatment.

[0024] The countercurrent reaction mechanism further includes a water supply pipe 25. The water supply pipe 25 is installed at the top of the de-alkalization tower 1. The water supply pipe 25 is used to transport pure water into the uppermost reaction chamber 12. Here, it is recorded that the pure water is water with a low impurity content that has not been mixed with red mud.

[0025] When treating red mud, in order to reduce the hindrance of the caustic alkali component contained in the red mud to subsequent treatment, it is necessary to perform de-alkalization treatment on the red mud. During the de-alkalization treatment, the carbon dioxide de-alkalization method makes the two wastes of blast furnace gas and red mud slurry interact with each other, which can not only purify the blast furnace gas and utilize the waste heat in the blast furnace gas, but also promote the conversion of the caustic alkali in the red mud slurry into soluble salts. When using carbon dioxide to perform de-alkalization treatment on red mud, in order to improve the reaction efficiency between carbon dioxide and red mud, a countercurrent reaction mechanism is provided in the present invention.

[0026] Specifically, in the red mud carbonization and de-alkalization treatment, the staff stably transports the red mud slurry to the reaction chamber 12 at the bottommost of the de-alkalization tower 1 through the liquid supply pipe 21, and mixes it with the aqueous solution already present in the reaction chamber 12. At this time, a large amount of soluble caustic alkali in the red mud slurry directly dissolves in the water, while the solid red mud settles to the bottom of the reaction chamber 12. The mud pump 22 installed on the de-alkalization tower 1 continuously transports the red mud slurry with a higher solid content at the bottom end of the reaction chamber 12 to the upper-level reaction chamber 12. The red mud slurry at the bottom end of the upper-level reaction chamber 12 is pumped by its corresponding mud pump 22 to a higher layer. When the red mud slurry reaches the topmost reaction chamber 12 and the liquid level is flush with the top end of the air supply pipe 24, the red mud slurry in the topmost reaction chamber 12 then flows downward along the multiple air supply pipes 24 in sequence. During this process, due to the red mud slurry being diluted multiple times, the soluble alkali in the red mud slurry is rapidly separated. At the same time, the blast furnace gas and pure water are respectively transported to the topmost reaction chamber 12 through the gas supply pipe 2 and the water supply pipe 25. And with the continuous supply of the blast furnace gas and pure water, the air pressure in the topmost reaction chamber 12 increases and the liquid level rises. Under the guidance of the air supply pipe 24, the gas flows along the air supply pipe 24 and, under the action of the air pressure, displaces the liquid inside the air supply pipe 24 to carry out aeration in the lower-level reaction chamber 12. As the air pressure in the lower-level reaction chamber 12 increases, the gas flows into the lower-level reaction chamber 12 in sequence along the multiple air supply pipes 24 arranged in sequence. During this process, the gas contacts the red mud slurry, causing the carbon dioxide in the gas to carbonize and de-alkalize the red mud. At the same time, carbon dioxide also dissolves in the water and is further used to carbonize and de-alkalize the red mud. In addition, due to the continuous water supply of the water supply pipe 25, the aqueous solution in the reaction chamber 12 is diluted, causing the soluble salts generated by de-alkalization to gradually flow downward into the lower-level reaction chamber 12. Therefore, finally in the topmost reaction chamber 12, a red mud slurry with lower salt and alkali contents is formed. After subsequent separation, de-alkalized red mud can be obtained.

[0027] By setting up a countercurrent reaction mechanism, when the present invention conducts de-alkalization treatment on red mud, it controls the red mud to move from bottom to top, while the gas and water move from top to bottom. Therefore, the salt content in the reaction chamber 12 closer to the top gradually decreases, the carbon dioxide content gradually increases, and the soluble alkali content gradually decreases. On the one hand, during the upward movement of the red mud, the soluble alkali is gradually removed step by step. After eliminating the hindrance of the soluble alkali to the carbon cycle of the red mud, it is convenient to use the gradually increasing concentration of carbon dioxide to carry out carbonization reaction on the insoluble alkali in the red mud, and finally it is formed in the topmost reaction chamber 12. On the other hand, due to the continuous water supply of the top water supply pipe 25, by using the flow of water, the soluble salts generated by the de-alkalization reaction are gradually washed to the bottommost reaction chamber 12 to form high-salt wastewater, which is convenient for subsequent recovery of components such as sodium carbonate in it.

[0028] As a preferred embodiment of the present invention, a heat exchange tube 26 is installed in the lowermost reaction chamber 12. 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 a blast furnace flue gas pumping device. An exhaust pipe 27 is installed on the dealkalization tower 1.

[0029] A jacket 28 is sleeved outside the dealkalization tower 1. A heat preservation cavity 29 is formed between the jacket 28 and the dealkalization tower 1. The exhaust pipe 27 extends into the heat preservation cavity 29. A gas-liquid separator 3 is installed above the dealkalization tower 1. The exhaust end of the gas-liquid separator 3 is conductively connected to the outside, and the liquid discharge end of the gas-liquid separator 3 is conductively connected to the water supply pipe 25.

[0030] During continuous reaction, due to the relatively high temperature in the initial blast furnace flue gas, in order to make the temperature in 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 lowermost reaction chamber 12. After heat exchange with the high-salt wastewater in the lowermost 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 for water washing, and finally flows into the lowermost reaction chamber 12. With the continuous transportation of the blast furnace flue gas, steam gradually generates in the high-salt wastewater in the uppermost reaction chamber 12. The steam mixed with gas flows along the exhaust pipe 27. In the present invention, the exhaust pipe has at least two openings. One opening leads into the jacket 28, so that the steam and the air flow enter the jacket 28 together. When the steam rises in the heat preservation cavity 29, it can cooperate with the flow of the blast furnace flue gas to perform heat preservation treatment on multiple reaction chambers 12. When the steam and the water-washed blast furnace flue gas enter the gas-liquid separator 3, under the action of the gas-liquid separator 3, the steam condenses into water and flows into the reaction chamber 12 through the water supply pipe 25, which is used to wash the soluble salts to the lowermost reaction chamber 12, while the water-washed blast furnace flue gas is discharged to the outside through the gas-liquid separator 3. After opening the other opening of the exhaust pipe 27, the discharged steam and the water-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. After continuous reaction for a period of time, the pumping of new red mud slurry is stopped. During the continuous heat exchange of the blast furnace flue gas, the high-salt wastewater in the lowermost reaction chamber 12 is gradually concentrated, and finally the drain pipe 23 is opened to discharge the high-salt wastewater.

[0031] By setting the heat exchange tube 26 and the jacket 28, in the carbonization dealkalization operation of red mud, with the continuous transportation of high-temperature blast furnace flue gas, the waste heat of the blast furnace flue gas is utilized to continuously heat the high-salt wastewater converged in the lowermost reaction chamber 12, so that the water component in the high-salt wastewater returns to the uppermost reaction chamber 12 in the form of steam and condensed water, which can not only save the use of water resources, but also converge the salt components. At the same time, the discharged steam as an intermediate product can also provide economic value for the reaction system.

[0032] As a preferred embodiment of the present invention, the aeration pipe 24 is rotatably installed on the partition plate 11 through a bearing. The aeration pipe 24 is arranged in a three-pronged shape. The bottom end of the aeration pipe 24 is inlaid with a guide pipe 4. The guide pipe 4 is provided with openings along the circumferential direction of the reaction chamber 12. In the present invention, the openings on the guide pipe 4 are evenly distributed, and overflow valves are installed in the openings to control the air pressure in the reaction chamber 12 in cooperation with the water pressure.

[0033] The partition plates 11 are all arranged in a conical shape with the openings facing upward. The input ends of the slurry pumps 22 all extend to the conical bottoms of the partition plates 11, and the output ends of the slurry pumps 22 all extend above the corresponding guide pipes 4.

[0034] During step-by-step aeration and alkali removal, the blast furnace flue gas enters the next-stage reaction chamber 12 through the sequentially arranged aeration pipes 24 in the reaction chamber 12 at the top end. During this process, under the action of air pressure, the flue gas enters the aeration pipe 24. After displacing the solution in the aeration pipe 24 and the guide pipe 4, it is ejected outward from the openings on the side wall of the guide pipe 4. Since the guide pipe 4 is provided with openings along the circumferential direction of the reaction chamber 12, under the reaction force formed by the air flow jet, the guide pipe 4 and the aeration pipe 24 rotate. On the one hand, the rotation makes the aeration operation of the red mud slurry in the reaction chamber 12 more uniform, facilitating the reaction of carbon dioxide with the alkali components in the red mud. On the other hand, due to the continuous unidirectional rotation, the solution in the reaction chamber 12 rotates, and then the red mud particles settled at the bottom of the reaction chamber 12 can converge towards the center of the partition plate 11, facilitating the extraction of red mud particles by the slurry pump 22 and making the red mud particles gradually converge towards the reaction chamber 12 at the topmost end.

[0035] As a preferred embodiment of the present invention, a dehydration tank 5 is installed at the top end of the alkali removal tower 1. A filter bag 51 is fixedly installed in the dehydration tank 5. The output end of the slurry pump 22 corresponding to the reaction chamber 12 at the topmost end extends above the filter bag 51. The bottom of the dehydration tank 5 is conductively connected to the water supply pipe 25.

[0036] The dehydration tank 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.

[0037] In order to separate the de-alkalized 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 plate 11 and are pumped by the mud pump 22 corresponding to the top reaction chamber 12 and pumped into the filter bag 51 in the dewatering tank 5. Under the filtering action of the filter bag 51, the red mud particles are separated from water. Among them, 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 dewatering tank 5 along the air supply pipe 2. At this time, the flue gas is in a high-temperature and dry state. When the flue gas contacts the red mud, 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.

[0038] As a preferred embodiment of the present invention, it further includes a magnetic separator for magnetic separation of red mud, a high-temperature reduction furnace for carbon thermal reduction of de-alkalized red mud, and a reaction kettle for acid leaching. The smoke exhaust port of the high-temperature reduction furnace transports blast furnace flue gas to the aeration de-sodium equipment through a pipeline, combining the high-temperature reduction furnace with the aeration de-alkalization equipment, effectively reducing the total amount of waste finally discharged from the reaction system.

[0039] A method for preparing aluminum chloride solution by atmospheric pressure leaching of red mud, the method comprising the following steps: S1. Magnetic separation: After the original red mud is crushed and ground, it is introduced into a magnetic separator, and after magnetic separation, a ferromagnetic component and a non-magnetic component are obtained; S2. Carbonization de-alkalization: The ferromagnetic component obtained in S1 is mixed with water to form a red mud slurry, and the red mud slurry is introduced into an aeration de-alkalization 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 °C for 2H of carbonization reaction. 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 flow downward step by step from the top reaction chamber 12 to promote the de-alkalization of red mud. After the reaction is completed, it is filtered and dried to obtain de-sodium red mud; S4. Carbon thermal reduction: Add carbon powder to the de-sodium red mud and transfer it to a high-temperature reduction furnace for heating to 1550 - 1750 °C. After 15 - 120 min of high-temperature carbon thermal reduction, the iron-silicon alloy phase and the slag are separated by density difference; S5. Atmospheric pressure acid leaching: The slag and HCL solution are mixed in a reaction kettle and reacted at 90 - 105 °C for 30 - 120 min. After the reaction is completed, after solid-liquid separation, the obtained filtrate is the aluminum chloride solution.

[0040] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. An apparatus for preparing aluminum chloride solution by atmospheric pressure leaching of red mud, including an aeration and alkali removal device for removing sodium from red mud. The aeration and alkali removal device consists of an alkali removal tower (1) and an air supply pipe (2). The alkali removal tower (1) is a cavity-type structure, and the air supply pipe (2) is installed on the alkali removal tower (1). The air supply pipe (2) is used to transport blast furnace gas into the alkali removal tower (1). It is characterized in that: It also includes a countercurrent reaction mechanism installed inside the alkali removal tower (1). The countercurrent reaction mechanism is used to control the countercurrent reaction between red mud slurry and carbon dioxide gas flow. The countercurrent reaction mechanism includes an air injection pipe (24), a liquid supply pipe (21), a slurry pump (22), a drain pipe (23), and a partition plate (11). A plurality of partition plates (11) are fixedly installed in the inner cavity of the alkali removal tower (1). The partition plates (11) divide the inner cavity of the alkali removal tower (1) into a plurality of non-communicating reaction chambers (12). A liquid supply pipe (21) is installed on the alkali removal tower (1). The liquid supply pipe (21) is connected to the bottommost reaction chamber (12) in a conducting manner. The liquid supply pipe (21) is used to transport red mud slurry. A plurality of slurry pumps (22) are installed on the alkali removal tower (1). The slurry pumps (22) are used to transport red mud slurry in adjacent two 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 slurry pumps (22) one by one. A drain pipe (23) is installed on the alkali removal tower (1). The drain pipe (23) is connected to the bottommost reaction chamber (12) in a conducting manner. The air supply pipe (2) extends into the topmost reaction chamber (12). Air injection pipes (24) are installed on the partition plates (11). The air injection pipes (24) are used to transport the gas in the upper reaction chamber (12) to the lower reaction chamber (12). The bottom end of the air injection 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 air injection 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 atmospheric pressure leaching of red mud according to claim 1, wherein: The countercurrent reaction mechanism further includes a water supply pipe (25). The water supply pipe (25) is installed at the top of the alkali removal tower (1). The water supply pipe (25) is used to transport pure water into the topmost reaction chamber (12).

3. The device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud according to claim 2, characterized in that: A heat exchange pipe (26) is installed in the bottommost reaction chamber (12). One end of the heat exchange pipe (26) is connected to the air supply pipe (2) in a conducting manner, and the other end is connected to a blast furnace gas pumping device. An exhaust pipe (27) is installed on the alkali removal tower (1).

4. The device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud according to claim 3, characterized in that: A jacket (28) is sleeved outside the alkali removal tower (1). A heat preservation chamber (29) is formed between the jacket (28) and the alkali removal tower (1). The exhaust pipe (27) extends into the heat preservation chamber (29). An air-liquid separator (3) is installed above the alkali removal tower (1). The exhaust end of the air-liquid separator (3) is connected to the outside in a conducting manner, and the liquid discharge end of the air-liquid separator (3) is connected to the water supply pipe (25) in a conducting manner.

5. The device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud according to claim 2 or 4, characterized in that: The aeration pipe (24) is rotatably mounted on the partition plate (11) through a bearing. The aeration pipe (24) is arranged in a three-pronged shape. A guide pipe (4) is embedded and installed at the bottom end of the aeration pipe (24). The guide pipe (4) is provided with an opening along the circumferential direction of the reaction chamber (12).

6. The device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud according to claim 5, characterized in that: The partition plates (11) are all arranged in a conical shape with the opening facing upward. The input ends of the slurry pumps (22) all extend to the conical bottom of the partition plates (11). The output ends of the slurry pumps (22) all extend above the corresponding guide pipes (4).

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

8. The device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud according to claim 7, characterized in that: The dehydration tank (5) is located in the middle of the air supply pipe (2). 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 atmospheric pressure leaching of red mud according to claim 8, wherein: It also includes a magnetic separator for magnetic separation of red mud, a high-temperature reduction furnace for carbothermal reduction of dealkalized red mud, and a reaction kettle for acid leaching. The smoke outlet of the high-temperature reduction furnace conveys blast furnace gas into the aeration and sodium removal equipment through a pipeline.

10. A method for preparing aluminum chloride solution by atmospheric pressure leaching of red mud, characterized in that: This method uses the device for preparing aluminum chloride solution by atmospheric pressure leaching of red mud described in claim 9. This method includes the following steps: S1. Magnetic separation: The original red mud is crushed and ground and then fed into the magnetic separator. After magnetic separation, a ferromagnetic component and a non-magnetic component are obtained. S2. Carbonization and dealkalization: The ferromagnetic component obtained in S1 is mixed with water to form a red mud slurry, and the red mud slurry is fed into the aeration and dealkalization equipment. Carbon dioxide is continuously introduced under the conditions of a pressure of 3.8 - 4.2 Mpa and a temperature of 45 - 55 °C for a carbonization reaction of 2H. S3. Countercurrent reaction: After the red mud slurry enters the lowermost reaction chamber (12), it is pumped upward step by step by the slurry pump (22). The blast furnace gas and water flow downward step by step from the topmost reaction chamber (12) to promote the dealkalization of the red mud. After the reaction, it is filtered and dried to obtain de-sodium red mud. S4. Carbothermal reduction: Carbon powder is added to the de-sodium red mud and transferred to the high-temperature reduction furnace for heating to 1550 - 1750 °C. After high-temperature carbothermal reduction for 15 - 120 min, the ferrosilicon alloy phase and the slag are separated by density difference. S5. Atmospheric pressure acid leaching: The slag and the HCL solution are mixed in the reaction kettle and reacted at 90 - 105 °C for 30 - 120 min. After the reaction, after solid-liquid separation, the obtained filtrate is the aluminum chloride solution. Wherein, the mass ratio of the de-sodium red mud to the carbon powder in S4 is 100:

8. Wherein, the solid-liquid ratio of the hydrochloric acid solution to the slag in S5 is 5 - 12 ml / g.

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