Method for co-production of pseudo-boehmite and sodium bicarbonate

Abstract

The invention discloses a method for co-production of pseudo-boehmite and sodium bicarbonate. The method comprises the following steps: introducing a sodium metaaluminate aqueous solution through a liquid phase inlet of a gel forming reactor, introducing carbon dioxide through a gas phase inlet of the gel forming reactor, carrying out a reaction in the gel forming reactor, respectively discharging a gas phase and a solid-liquid mixed phase, separating the solid-liquid mixed phase through a solid-liquid separation device to obtain a solid phase, namely a pseudo-boehmite crude product, mixing a liquid phase obtained by separation with a gas phase discharged from the gel forming reactor in a mixing container to obtain a mixed material, introducing the mixed material into an electrodialysis membrane treatment device, concentrating the mixed material through the electrodialysis membrane treatment device to obtain a concentrated solution and a thin solution, introducing the concentrated solution into a reduced pressure distillation device, and performing reduced pressure distillation to obtain the pseudo-boehmite. A solid phase obtained after reduced pressure distillation is a sodium bicarbonate product.

Description

Technical Field

[0001] The present application relates to a method for co-producing sodium bicarbonate using pseudo-boehmite, and belongs to the field of environmental protection. Background Art

[0002] The physicochemical properties of pseudo-boehmite determine its application, and the physicochemical properties of pseudo-boehmite are directly related to the preparation method. Therefore, the study of a greener, more economical, simpler and more efficient preparation method of pseudo-boehmite or the optimization and improvement of the existing preparation method has become a hot topic of research at home and abroad in recent years. The carbonization method is currently the lowest cost method for industrial production of pseudo-boehmite. It uses sodium aluminate solution and carbon dioxide as raw materials, and obtains pseudo-boehmite through gelling reaction, aging, washing, drying and other steps.

[0003] After aging, pseudo-boehmite will exist in the form of colloids. The colloid particles themselves are charged and will adsorb Na + The gaps between the particles also contain a certain amount of Na + , repeated washing is required to remove the Na + It is estimated that 40 tons of washing water are needed to produce 1 ton of pseudo-boehmite. If the glue and aging water are included, the water consumption will be even higher. Washing water contains a large amount of sodium carbonate and sodium bicarbonate. Separating and treating this part of the brine, recycling the purified water, and recycling the ions has both economic and environmental benefits. Patent CN113277536B discloses a method for saving washing water: adding an alkaline modifier to the pseudo-boehmite aging liquid for replacement reaction, thereby achieving the effect of reducing the amount of washing water, but this method requires the introduction of new additives; Patent CN111592022B uses secondary washing liquid instead of new water to make sodium aluminate solution, and the secondary washing liquid is recycled and comprehensively utilized to reduce the amount of washing water, but the precipitation effect of only reusing the secondary washing liquid is not obvious.

[0004] At the same time, about 1 ton of carbon dioxide is needed to produce 1 ton of pseudo-boehmite. According to theoretical calculations, 0.65 tons of carbon dioxide are needed in the reaction process, which means that 0.35 tons of carbon dioxide do not participate in the reaction for every ton of pseudo-boehmite produced, and most manufacturers directly discharge it. The "2024-2030 China Pseudo-boehmite Industry Demand Forecast and Development Feasibility Study Report" points out that the pseudo-boehmite production capacity in 2024 is 172,000 tons. With the continuous upgrading of domestic industries, the demand for pseudo-boehmite continues to increase. By 2030, the pseudo-boehmite production capacity will reach 260,000 tons, and the carbon dioxide emissions that do not participate in the reaction will reach 90,000 tons. How to adjust the industrial structure of pseudo-boehmite production by carbonization and promote green and low-carbon production has become an urgent problem to be solved. Summary of the invention

[0005] In view of the above, in view of the shortcomings of the prior art, the present invention provides a pseudo-boehmite waste resource process, the tail gas in the carbonization gelling process is introduced into the filtrate produced by the previous preparation of pseudo-boehmite, the sodium carbonate and sodium bicarbonate in the filtrate are converted into pure sodium bicarbonate, and then the pure sodium bicarbonate aqueous solution is further concentrated by a membrane device, the low-conductivity fresh water is used as the water for the next synthesis of pseudo-boehmite, the high-conductivity concentrated water is subjected to reduced pressure distillation, the distillate is also used as the water for the next synthesis of pseudo-boehmite, and the pure sodium bicarbonate solid is obtained by rotary evaporation for resource treatment. This process has the advantages of low carbon, low water consumption, and waste resource utilization.

[0006] According to one aspect of the present application, a method for co-producing sodium bicarbonate with pseudo-boehmite is provided, using the following apparatus:

[0007] It includes a gelling reactor, a solid-liquid separation device, a mixing reactor, an electrodialysis membrane treatment device, and a vacuum distillation device;

[0008] The gelling reactor comprises a liquid phase inlet, a gas phase inlet, a gas phase outlet and a solid-liquid mixed phase outlet;

[0009] The solid-liquid separation device comprises a solid-liquid mixed phase inlet, a solid phase outlet and a liquid phase outlet;

[0010] The mixing reactor comprises a liquid phase inlet, a gas phase inlet, and a material outlet;

[0011] The electrodialysis membrane treatment device comprises a material inlet, a concentrated solution outlet and a diluted solution outlet;

[0012] The vacuum distillation device comprises a concentrated liquid inlet, a liquid phase outlet and a solid phase outlet;

[0013] The solid-liquid mixed phase outlet of the gelling reactor is connected to the solid-liquid mixed phase inlet pipeline of the solid-liquid separation device;

[0014] The liquid phase outlet of the solid-liquid separation device is connected to the liquid phase inlet pipeline of the mixing reactor;

[0015] The gas phase outlet of the gelling reactor is connected to the gas phase inlet pipeline of the mixing reactor;

[0016] The material outlet of the mixing reactor is connected to the material inlet pipeline of the electrodialysis membrane treatment device;

[0017] The concentrate outlet of the electrodialysis membrane treatment device is connected to the concentrate inlet pipeline of the vacuum distillation device;

[0018] The concentrated liquid outlet and the dilute liquid outlet of the electrodialysis membrane treatment device are both provided with a conductivity detector and a valve, the conductivity detector is used to detect the conductivity of the liquid discharged from the concentrated liquid outlet and the dilute liquid outlet, and the valve is used to control the on-off of the pipeline;

[0019] The mixing reactors are connected in series one by one in 1 to 5 according to actual needs, preferably 2 to 4. When carbon dioxide overflows from the tail gas of a reactor, the overflow gas enters the next series reactor for further processing.

[0020] The following steps are involved:

[0021] A sodium aluminate aqueous solution is introduced through a liquid phase inlet of a gelling reactor, and carbon dioxide is introduced through a gas phase inlet of the gelling reactor, and a reaction occurs in the gelling reactor. A gas phase (i.e., tail gas carbon dioxide) and a solid-liquid mixed phase are discharged respectively, and the solid-liquid mixed phase is separated by a solid-liquid separation device, and the separated solid phase is a pseudo-boehmite crude product. After aging and washing, a pseudo-boehmite product can be obtained, and the separated liquid phase is mixed with the gas phase discharged from the gelling reactor in a mixing container to obtain a mixed material, which is introduced into an electrodialysis membrane treatment device, and concentrated by the electrodialysis membrane treatment device to obtain a concentrated solution and a diluted solution, and the concentrated solution is introduced into a vacuum distillation device for vacuum distillation, and the solid phase obtained after the vacuum distillation is a sodium bicarbonate product;

[0022] The conductivity of the concentrated solution discharged from the electrodialysis membrane treatment device is controlled to be 70-100ms / cm, and the conductivity of the dilute solution is controlled to be 300-2000us / cm.

[0023] The concentration of the sodium aluminate aqueous solution is 6.5-10 wt %;

[0024] Optionally, the concentration of the sodium aluminate aqueous solution is any value of 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt% or any range between two of them.

[0025] The flow rate of the carbon dioxide is 3 to 20 L / min;

[0026] Optionally, the flow rate of the carbon dioxide is any value among 3 L / min, 5 L / min, 10 L / min, 15 L / min, 20 L / min, or a range value between any two of them.

[0027] The mass ratio of sodium aluminate to carbon dioxide in the sodium aluminate aqueous solution is 0.65 to 1.45:1;

[0028] Optionally, the mass ratio of sodium aluminate to carbon dioxide in the sodium aluminate aqueous solution is any value among 0.65:1, 0.75:1, 0.85:1, 0.95:1, 1.05:1, 1.15:1, 1.25:1, 1.35:1, 1.45:1, or a range value between any two of them.

[0029] The reaction end point pH of the reaction in the gelling reactor is 7.5 to 10, preferably 7.8 to 9.5.

[0030] Optionally, the reaction endpoint pH of the reaction in the gelling reactor is any value among 7.5, 8, 8.5, 9, 9.5, 10 or a range value between any two of them.

[0031] The material inlet of the electrodialysis membrane treatment device is provided with filter paper or filter membrane.

[0032] The pressure of the reduced pressure distillation is -0.095 to -0.098 MPa;

[0033] Optionally, the pressure of the reduced pressure distillation is any value among -0.095Mpa, -0.096Mpa, -0.097Mpa, -0.098Mpa, or a range value between any two of them.

[0034] The temperature of the reduced pressure distillation is 40 to 80°C, preferably 50 to 70°C.

[0035] Optionally, the temperature of the reduced pressure distillation is any value of 40°C, 50°C, 60°C, 70°C, 80°C, or a range between any two of them.

[0036] The light liquid discharged from the light liquid outlet of the electrodialysis membrane treatment device and the liquid phase discharged from the liquid phase outlet of the vacuum distillation device can be reused as industrial water.

[0037] The invention recycles the tail gas carbon dioxide of the gelling reaction in the preparation process of pseudo-boehmite to convert the mixed salt solution of sodium bicarbonate and sodium carbonate in the previous pulping liquid into a pure phase sodium bicarbonate solution, and then treats the concentrated brine through an electrodialysis membrane to obtain solid sodium bicarbonate for resource treatment. The low-concentration brine obtained by electrodialysis and distillation is used as the pulping and aging liquid of the next pseudo-boehmite. The invention is low-carbon, no waste is generated, and the cost is low, which is conducive to industrial operation.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) Recycling unreacted carbon dioxide can convert it into valuable resources, which is in line with the concept of low-carbon environmental protection and has certain economic value;

[0040] (2) The salt solution purified by electrodialysis membrane concentration can effectively reduce energy consumption and is suitable for industrial production. At the same time, the low-conductivity water obtained by membrane treatment can be reused to reduce water resource consumption and reduce the environmental pressure of enterprises.

[0041] (3) The waste salt components produced by the preparation of pseudo-boehmite are purified to obtain a single solid salt, thereby realizing the resource utilization of solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1Schematic diagram of a device according to an embodiment of the present application.

[0043] Among them, 1 is the liquid phase inlet of the gelling reactor; 2 is the gas phase inlet of the gelling reactor; 3 is the connecting pipeline between the gas phase outlet of the gelling reactor and the gas phase inlet of the mixing reactor; 4 is the connecting pipeline between the solid-liquid mixed phase outlet of the gelling reactor and the solid-liquid mixed phase inlet of the solid-liquid separation device; 5 is the connecting pipeline between the liquid phase outlet of the solid-liquid separation device and the liquid phase inlet of the mixing reactor; 6 is the solid phase outlet of the solid-liquid separation device; 7 is the connecting pipeline between the material outlet of the mixing reactor and the material inlet of the electrodialysis membrane treatment device; 8 is the dilute liquid outlet of the electrodialysis membrane treatment device; 9 is the connecting pipeline between the concentrated liquid outlet of the electrodialysis membrane treatment device and the concentrated liquid inlet of the vacuum distillation device; 10 is the liquid phase outlet of the vacuum distillation device; 11 is the solid phase outlet of the vacuum distillation device. DETAILED DESCRIPTION

[0044] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0045] The electrodialysis membrane area of ​​the present invention is 8m 2 , effective area 2.6m 2 Under the action of a direct current electric field, the selective permeability of the ion exchange membrane is utilized, and the charged ions migrate directionally through the ion exchange membrane and are separated from the aqueous solution and other uncharged components, thereby achieving the purpose of concentrating, diluting, refining and purifying the solution.

[0046] The conductivity parameter in the present invention adopts a Mettler portable conductivity meter. Conductivity is a manifestation of the electrical conductivity of an electrolyte solution and is usually proportional to the concentration of ions in the solution. Therefore, the total concentration of ions or the salt content in the solution can be determined by measuring the conductivity.

[0047] Device example

[0048] like Figure 1 The device shown.

[0049] It includes a gelling reactor, a solid-liquid separation device, a mixing reactor, an electrodialysis membrane treatment device, and a vacuum distillation device;

[0050] The gelling reactor comprises a liquid phase inlet, a gas phase inlet, a gas phase outlet and a solid-liquid mixed phase outlet;

[0051] The solid-liquid separation device comprises a solid-liquid mixed phase inlet, a solid phase outlet and a liquid phase outlet;

[0052] The mixing reactor comprises a liquid phase inlet, a gas phase inlet, and a material outlet;

[0053] The electrodialysis membrane treatment device comprises a material inlet, a concentrated solution outlet and a diluted solution outlet;

[0054] The vacuum distillation device comprises a concentrated liquid inlet, a liquid phase outlet and a solid phase outlet;

[0055] The solid-liquid mixed phase outlet of the gelling reactor is connected to the solid-liquid mixed phase inlet pipeline of the solid-liquid separation device;

[0056] The liquid phase outlet of the solid-liquid separation device is connected to the liquid phase inlet pipeline of the mixing reactor;

[0057] The gas phase outlet of the gelling reactor is connected to the gas phase inlet pipeline of the mixing reactor;

[0058] The material outlet of the mixing reactor is connected to the material inlet pipeline of the electrodialysis membrane treatment device;

[0059] The concentrate outlet of the electrodialysis membrane treatment device is connected to the concentrate inlet pipeline of the vacuum distillation device;

[0060] The concentrated liquid outlet and the dilute liquid outlet of the electrodialysis membrane treatment device are both provided with a conductivity detector and a valve, the conductivity detector is used to detect the conductivity of the liquid discharged from the concentrated liquid outlet and the dilute liquid outlet, and the valve is used to control the on-off of the pipeline;

[0061] The mixing reactors are connected in series one by one in 1 to 5 according to actual needs.

[0062] The process is as follows:

[0063] A sodium aluminate aqueous solution is introduced through a liquid phase inlet of a gelling reactor, and carbon dioxide is introduced through a gas phase inlet of the gelling reactor, and a reaction occurs in the gelling reactor, and a gas phase and a solid-liquid mixed phase are discharged respectively. The solid-liquid mixed phase is separated by a solid-liquid separation device, and the separated solid phase is the pseudo-boehmite product. The separated liquid phase is mixed with the gas phase discharged from the gelling reactor in a mixing container to obtain a mixed material, which is introduced into an electrodialysis membrane treatment device, and concentrated by the electrodialysis membrane treatment device to obtain a concentrated solution and a diluted solution. The concentrated solution is introduced into a vacuum distillation device for vacuum distillation, and the solid phase obtained after the vacuum distillation is the sodium bicarbonate product;

[0064] The conductivity of the concentrated solution discharged from the electrodialysis membrane treatment device is controlled to be 70-100ms / cm, and the conductivity of the dilute solution is controlled to be 300-2000us / cm.

[0065] Example 1

[0066] The apparatus described in the apparatus example is used.

[0067] Step 1): 14.5 kg of sodium aluminate aqueous solution (concentration 9.5 wt%) is added to the gelling reactor, and carbon dioxide is introduced at a flow rate of 6 L / min. The pH value at the reaction end point is 8. The tail gas of the gelling reactor is connected in series to two mixing reactors in sequence. 40 kg of the brine solution produced by the gelling reactor to prepare pseudo-boehmite is introduced into the mixing reactor together, wherein the content of sodium carbonate and sodium bicarbonate salts is 2%.

[0068] Step 2): The sodium bicarbonate aqueous solution obtained in the mixing reactor of step 1) is filtered with a filter membrane, and then passed into an electrodialysis membrane treatment device, and the concentrated chamber and the dilute chamber are respectively loaded with equal amounts of sodium bicarbonate aqueous solution. After the treatment, 8.5 kg of concentrated solution with a conductivity of 88 ms / cm and 32.5 kg of dilute solution with a conductivity of 349 us / cm are obtained. The dilute solution is used as water for preparing pseudo-boehmite next time.

[0069] Step 3): The concentrated solution obtained in step 2) is subjected to reduced pressure distillation at a water temperature of 60° C. After the distillation, 1.1 kg of sodium bicarbonate solid and 7.3 kg of distilled water are obtained, which are used as water for the next preparation of pseudo-boehmite.

[0070] Example 2

[0071] The apparatus described in the apparatus example is used.

[0072] Step 1): 20 kg of sodium aluminate aqueous solution (concentration 9.2 wt%) is added to the gelling reactor, and carbon dioxide is introduced at a flow rate of 15 L / min. The pH value at the reaction end is 8.5. The tail gas of the gelling reactor is connected in series to three mixing reactors in sequence. 120 kg of the brine solution produced by the gelling reactor to prepare pseudo-boehmite is introduced into the mixing reactor together, wherein the content of sodium carbonate and sodium bicarbonate salts is 1%.

[0073] Step 2): The sodium bicarbonate aqueous solution obtained in the mixing reactor of step 1) is filtered with a filter membrane, and then passed into an electrodialysis membrane treatment device, and the concentrated chamber and the dilute chamber are respectively loaded with equal amounts of sodium bicarbonate aqueous solution. After the treatment, 60 kg of concentrated solution with a conductivity of 79 ms / cm and 62 kg of dilute solution with a conductivity of 420 us / cm are obtained. The dilute solution is used as water for preparing pseudo-boehmite next time.

[0074] Step 3): The concentrated solution obtained in step 2) is subjected to reduced pressure distillation at a water temperature of 50° C. After the distillation, 3.3 kg of sodium bicarbonate solid and 56 kg of distilled water are obtained, which are used as water for the next preparation of pseudo-boehmite.

[0075] Example 3

[0076] The apparatus described in the apparatus example is used.

[0077] Step 1): 40 kg of sodium aluminate aqueous solution (concentration wt 7%) is added to the gelling reactor, and carbon dioxide is introduced at a flow rate of 19 L / min. The pH value at the reaction end is 7.5. The tail gas of the gelling reactor is connected in series to 5 mixing reactors in sequence. 290 kg of the brine solution produced by the gelling reactor to prepare pseudo-boehmite is introduced into the mixing reactor together, wherein the content of sodium carbonate and sodium bicarbonate salts is 1.5%.

[0078] Step 2): The sodium bicarbonate aqueous solution obtained in the mixing reactor of step 1) is filtered with a filter membrane, and then passed into an electrodialysis membrane treatment device, and the concentrated chamber and the dilute chamber are respectively loaded with equal amounts of sodium bicarbonate aqueous solution. After the treatment, 60 kg of concentrated solution with a conductivity of 72 ms / cm and 234 kg of dilute solution with a conductivity of 1320 us / cm are obtained. The dilute solution is used as water for preparing pseudo-boehmite next time.

[0079] Step 3): The concentrated solution obtained in step 2) is subjected to reduced pressure distillation at a water temperature of 75° C. After the distillation, 8 kg of solid sodium bicarbonate and 51 kg of distilled water are obtained, which are used as water for the next preparation of pseudo-boehmite.

[0080] Example 4

[0081] The apparatus described in the apparatus example is used.

[0082] Step 1): 20 kg of sodium aluminate aqueous solution (concentration 9.8 wt%) is added to the gelling reactor, and carbon dioxide is introduced at a flow rate of 10 L / min. The pH value at the reaction end point is 10. The tail gas of the gelling reactor is connected in series to two mixing reactors in sequence. 45 kg of the brine solution produced by the gelling reactor to prepare pseudo-boehmite is introduced into the mixing reactor together, wherein the content of sodium carbonate and sodium bicarbonate salts is 1.7%.

[0083] Step 2): The sodium bicarbonate aqueous solution obtained in the mixing reactor of step 1) is filtered with a filter membrane, and then passed into an electrodialysis membrane treatment device, and the concentrated chamber and the dilute chamber are respectively loaded with equal amounts of sodium bicarbonate aqueous solution. After the treatment, 11.25 kg of concentrated solution with a conductivity of 90 ms / cm and 35.25 kg of dilute solution with a conductivity of 700 us / cm are obtained. The dilute solution is used as water for preparing pseudo-boehmite next time.

[0084] Step 3): The concentrated solution obtained in step 2) is subjected to reduced pressure distillation at a water temperature of 65° C. After the distillation, 2.2 kg of sodium bicarbonate solid and 8.9 kg of distilled water are obtained, which are used as water for the next preparation of pseudo-boehmite.

[0085] Example 5

[0086] The apparatus described in the apparatus example is used.

[0087] Step 1): 14.5 kg of sodium aluminate aqueous solution (concentration 9.1 wt%) is added to the gelling reactor, and carbon dioxide is introduced at a flow rate of 15 L / min. The pH value at the reaction end is 7.5. The tail gas of the gelling reactor is connected in series to four mixing reactors in sequence. 60 kg of the brine solution produced by the gelling reactor to prepare pseudo-boehmite is introduced into the mixing reactor together, wherein the content of sodium carbonate and sodium bicarbonate salts is 2.5%.

[0088] Step 2): The sodium bicarbonate aqueous solution obtained in the mixing reactor of step 1) is filtered with a filter membrane, and then passed into an electrodialysis membrane treatment device, and the concentrated chamber and the dilute chamber are respectively loaded with equal amounts of sodium bicarbonate aqueous solution. After the treatment, 10 kg of concentrated solution with a conductivity of 85 ms / cm and 51 kg of dilute solution with a conductivity of 410 us / cm are obtained. The dilute solution is used as water for preparing pseudo-boehmite next time.

[0089] Step 3): The concentrated solution obtained in step 2) is subjected to reduced pressure distillation at a water temperature of 55° C. After the distillation, 2.3 kg of sodium bicarbonate solid and 7 kg of distilled water are obtained, which are used as water for the next preparation of pseudo-boehmite.

[0090] Example 6

[0091] The apparatus described in the apparatus example is used.

[0092] Step 1): 42.5 kg of sodium aluminate aqueous solution (concentration 8.4 wt%) is added to the gelling reactor, and carbon dioxide is introduced at a flow rate of 21 L / min. The pH value at the reaction end is 7.65. The tail gas of the gelling reactor is connected in series to four mixing reactors in sequence. 280 kg of the brine solution produced by the gelling reactor to prepare pseudo-boehmite is introduced into the mixing reactor together, wherein the content of sodium carbonate and sodium bicarbonate salts is 2%.

[0093] Step 2): The sodium bicarbonate aqueous solution obtained in the mixing reactor of step 1) is filtered with a filter membrane, and then passed into an electrodialysis membrane treatment device, and the concentrated chamber and the dilute chamber are respectively loaded with equal amounts of sodium bicarbonate aqueous solution. After the treatment, 84 kg of concentrated solution with a conductivity of 98 ms / cm and 200 kg of dilute solution with a conductivity of 1732 us / cm are obtained. The dilute solution is used as water for preparing pseudo-boehmite next time.

[0094] Step 3): The concentrated solution obtained in step 2) is subjected to reduced pressure distillation at a water temperature of 67° C. After the distillation, 9.6 kg of sodium bicarbonate solid and 73 kg of distilled water are obtained, which are used as water for the next preparation of pseudo-boehmite.

[0095] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for co-producing sodium bicarbonate from pseudo-boehmite, characterized in that: The following devices are used: It includes a gelling reactor, a solid-liquid separation device, a mixing reactor, an electrodialysis membrane treatment device, and a vacuum distillation device; The gelling reactor comprises a liquid phase inlet, a gas phase inlet, a gas phase outlet and a solid-liquid mixed phase outlet; The solid-liquid separation device comprises a solid-liquid mixed phase inlet, a solid phase outlet and a liquid phase outlet; The mixing reactor comprises a liquid phase inlet, a gas phase inlet, and a material outlet; The electrodialysis membrane treatment device comprises a material inlet, a concentrated solution outlet and a diluted solution outlet; The vacuum distillation device comprises a concentrated liquid inlet, a liquid phase outlet and a solid phase outlet; The solid-liquid mixed phase outlet of the gelling reactor is connected to the solid-liquid mixed phase inlet pipeline of the solid-liquid separation device; The liquid phase outlet of the solid-liquid separation device is connected to the liquid phase inlet pipeline of the mixing reactor; The gas phase outlet of the gelling reactor is connected to the gas phase inlet pipeline of the mixing reactor; The material outlet of the mixing reactor is connected to the material inlet pipeline of the electrodialysis membrane treatment device; The concentrate outlet of the electrodialysis membrane treatment device is connected to the concentrate inlet pipeline of the vacuum distillation device; The concentrated liquid outlet and the dilute liquid outlet of the electrodialysis membrane treatment device are both provided with a conductivity detector and a valve, the conductivity detector is used to detect the conductivity of the liquid discharged from the concentrated liquid outlet and the dilute liquid outlet, and the valve is used to control the on-off of the pipeline; The mixing reactors are connected in series one by one using 1 to 5 reactors according to actual needs; The following steps are involved: A sodium aluminate aqueous solution is introduced through a liquid phase inlet of a gelling reactor, and carbon dioxide is introduced through a gas phase inlet of the gelling reactor. A reaction occurs in the gelling reactor, and a gas phase and a solid-liquid mixed phase are discharged respectively. The solid-liquid mixed phase is separated by a solid-liquid separation device. The separated solid phase is a pseudo-boehmite crude product. After aging and washing, a pseudo-boehmite product can be obtained. The separated liquid phase is mixed with the gas phase discharged from the gelling reactor in a mixing container to obtain a mixed material, which is introduced into an electrodialysis membrane treatment device, concentrated by the electrodialysis membrane treatment device to obtain a concentrated solution and a diluted solution. The concentrated solution is introduced into a vacuum distillation device for vacuum distillation. The solid phase obtained after the vacuum distillation is a sodium bicarbonate product. The conductivity of the concentrated solution discharged from the electrodialysis membrane treatment device is controlled to be 70-100ms / cm, and the conductivity of the dilute solution is controlled to be 300-2000us / cm.

2. The method according to claim 1, characterized in that The concentration of the sodium aluminate aqueous solution is 6.5-10 wt %; The flow rate of the carbon dioxide is 3 to 20 L / min; The mass ratio of sodium aluminate to carbon dioxide in the sodium aluminate aqueous solution is 0.65 to 1.45:1; The reaction endpoint pH of the reaction in the gelling reactor is 7.5-10.

3. The method according to claim 1, characterized in that The material inlet of the electrodialysis membrane treatment device is provided with filter paper or filter membrane.

4. The method according to claim 1, characterized in that: The pressure of the reduced pressure distillation is -0.095 to -0.098 MPa; The temperature of the reduced pressure distillation is 40-80°C.

5. The method according to claim 1, characterized in that The light liquid discharged from the light liquid outlet of the electrodialysis membrane treatment device and the liquid phase discharged from the liquid phase outlet of the vacuum distillation device can be reused as industrial water.

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