A concentration device and concentration process for seawater bromine extraction

Abstract

This invention provides a concentration device and process for bromine extraction from seawater, belonging to the technical field of concentration devices and processes for bromine extraction from seawater. The process includes the following preparation steps: S1, drying seawater to form brine, adding acidic substances to generate free bromide ions, and then passing chlorine gas into the brine for oxidation to obtain an oxidized liquid containing bromine molecules; S2, blowing out the oxidized liquid using air convection to separate bromine molecules, obtaining bromine-containing air; S3, purification and absorption using an absorption tower, passing the bromine-containing air through the absorption layer inside the tower, circulating the absorption, and then discharging the waste gas. The absorption layer contains modified activated carbon; S4, washing the activated carbon with water at low temperature, allowing it to stand and dry, and eluting the bromine with an organic extractant to obtain a bromine-containing solution; S5, distilling the bromine-containing solution to obtain bromine of high purity. The process of this invention can extract bromine regardless of other mineral salts in seawater, and uses recyclable organic solvents to extract pure bromine, resulting in no pollution and low cost. A matching concentration device can remove and elute the absorption medium to complete the purification of bromine.

Description

Technical Field

[0001] This invention relates to the field of seawater bromine extraction technology, specifically to a seawater bromine extraction concentration device and concentration process. Background Technology

[0002] Bromine and its derivatives are important raw materials for the pharmaceutical industry and the production of flame retardants, drilling fluids, etc., with a large demand. Seawater bromine extraction technologies include steam distillation, air blowing, solvent extraction, precipitation, and adsorption, among which air blowing and steam distillation are widely used both domestically and internationally. The basic process of air blowing is acidification → oxidation → blowing → absorption → distillation; absorption processes commonly use alkali absorption and sulfur dioxide absorption, with absorbents including alkali, sulfur, iron filings, sodium bromide, etc.

[0003] A device for extracting bromine from seawater using an air blowing method, patent number CN111362343A, absorbs bromine from seawater by setting up an absorption tower liquid distributor and an absorption tower packing layer inside the absorption tower. The packing material used in the selective absorption area is a structured packing with a larger specific surface area, lower unit pressure drop, and higher mass transfer efficiency. However, the problem is that this invention requires the seawater to be clean and free from other mineral salts that could clog the pores of the packing to achieve good absorption efficiency. Therefore, the pretreatment of the seawater is costly and requires a large number of permeable membranes.

[0004] A seawater bromine extraction process with patent number CN115784160A involves recycling the acidification process and collecting the gas through blowing. However, in actual production, a large amount of acid waste liquid and harmful gases are generated. Furthermore, enrichment and recycling are required before the distillation process. The sulfur dioxide and chlorine used in the process both produce acid liquid, which generates waste liquid after use, making treatment difficult. Summary of the Invention

[0005] In view of this, the present invention provides a concentration process for bromine extraction from seawater, which can extract bromine regardless of other mineral salts in seawater, and uses recyclable organic solvents to extract pure bromine, which is pollution-free and low-cost; a matching concentration device can remove and wash the absorption medium in the process to complete the purification of bromine.

[0006] This invention provides a concentration process for bromine extraction from seawater, comprising the following preparation steps:

[0007] S1. Seawater is dried to form brine, acidic substances are added to generate free bromide ions, and chlorine gas is then passed into the brine to oxidize it, resulting in an oxidized liquid containing bromine molecules.

[0008] S2. Blow out, using air and oxidizing liquid to convection, separate bromine molecules, and obtain bromine-containing air;

[0009] S3. Purification and absorption: Using an absorption tower, bromine-containing air is passed through the absorption layer inside the absorption tower. After being absorbed in a cycle, the waste gas is discharged. The absorption layer contains modified activated carbon.

[0010] S4. Wash activated carbon with water at low temperature, let it stand and dry, and use an organic extractant to remove bromine to obtain a bromine-containing solution;

[0011] S5. After distilling the bromine-containing solution, bromine of higher purity is obtained.

[0012] This invention first concentrates seawater to initially concentrate bromide salts in the seawater. In this step, an acidic substance is used to convert the bromide salts into bromide ions in the seawater, which facilitates subsequent oxidation and extraction. After the bromide salts are converted into free bromide ions, chlorine gas is introduced into them for oxidation, which oxidizes the bromide ions into bromine molecules. The bromine molecules are distributed in the brine, which contains not only other salts but also hydrochloric acid and other oxidizing acidic substances, and contains a large number of impurities.

[0013] Secondly, the oxidizing liquid containing bromine molecules is introduced into the device for the blowing process. The oxidizing liquid flows downward from the top, while the air flows upward from the bottom, so that the air and the oxidizing liquid are in full contact. This blows the elemental bromine molecules out from the top of the tower, so that the bromine is initially separated from the oxidizing liquid and distributed in the blown air.

[0014] Then, bromine-containing air is introduced into the absorption tower to absorb and adsorb elemental bromine. The bromine in the air is adsorbed, and the air circulates in the absorption layer to increase the adsorption effect, and the remaining waste gas is discharged.

[0015] Next, the absorption layer is washed with water at low temperature to remove impurities other than bromine. Because the modified activated carbon has a strong binding ability with bromine, and the adsorption capacity between the activated carbon and bromine remains unchanged at low temperature, the bromine element will not be washed away by water. Other substances have a weaker binding ability with the absorption layer and are easily removed by water. Then, an organic extractant is used to elute the modified activated carbon in the absorption layer, removing the bromine from the surface of the modified activated carbon and concentrating the bromine in the organic extractant.

[0016] Finally, by exploiting the difference between the boiling point of bromine and that of the organic extractant, the bromine is distilled from the organic extractant by increasing the temperature. After condensation, a high-purity bromine product is obtained.

[0017] Furthermore, the acidic substance in S1 is hydrochloric acid, sulfuric acid, or ferric hydroxide.

[0018] Seawater contains a large amount of salt, which does not exist in the form of ions and is not easily oxidized. Therefore, bromine needs to be converted into free bromide ions through acid. Hydrochloric acid, sulfuric acid, or ferric hydroxide can effectively convert bromine salts into bromide ions.

[0019] Furthermore, the modifying material for the modified activated carbon in S3 is titanium dioxide, and the modification method is as follows:

[0020] The activated carbon was heated to 600℃ and then allowed to return to room temperature. It was then immersed in a 0.1-1.0 mol / L metatitanic acid solution, followed by the addition of sodium hydroxide for precipitation. The pH range was 8-10. The activated carbon was then aged at 100-200℃. Finally, the activated carbon was washed with water and dried to obtain modified activated carbon.

[0021] Activated carbon can effectively adsorb bromine, but it can also adsorb other substances. When desorbing, the desorption conditions of other substances and bromine are similar, thus producing a large amount of impurities. Titanium dioxide can increase the adsorption capacity of activated carbon for bromine, thereby forming different adsorption conditions with other substances, which facilitates the purification and separation of bromine.

[0022] Furthermore, the organic solvent extractant in S4 is methanol, ethanol, tert-butanol, tetrahydrofuran, 1,2-dimethoxyethane, hexane, or heptane.

[0023] When bromine is eluted using organic extractants on modified activated carbon after water washing, none of the above-mentioned substances will chemically react with bromine molecules. This is because they are usually used as non-reactive solvents, meaning their main function is to separate or extract compounds through physical dissolution.

[0024] Furthermore, the temperature of the low-temperature water washing in S4 is 5-15℃.

[0025] Washing with water within this temperature range can effectively prevent bromine from detaching from the activated carbon; higher temperatures will cause partial desorption of bromine.

[0026] Furthermore, when the organic extraction solvent is methanol or ethanol, a water washing operation is required before S5 distillation to separate the aqueous phase before distillation.

[0027] Since methanol and ethanol have low boiling points and are both volatile, water is used for displacement to dissolve bromine in the water. Subsequent distillation can then yield bromine with higher purity.

[0028] Another object of the present invention is to provide a concentration device for bromine extraction from seawater, including an oxidation tower, a blow-out tower, an absorption tower, an elution tank, and a distillation tower;

[0029] The absorption tower is equipped with multiple layers of corrugated plates, and an activated carbon layer is provided on the multiple corrugated plates. The modified activated carbon is located in the activated carbon layer. A sand core filter plate is provided above the activated carbon layer. A material replacement door is opened on the side wall of the absorption tower near the activated carbon layer.

[0030] The apparatus used in this invention adds an extra elution tank after absorption. After washing with water, the modified activated carbon is transferred to the elution tank for organic solvent desorption. To facilitate the transfer of the modified activated carbon, a material exchange door is used on the side wall of the absorption tower for the removal and insertion of activated carbon.

[0031] Furthermore, the absorption tower is equipped with multiple feed pipes, and the lower part of the absorption tower is equipped with a water outlet and a circulation port.

[0032] The absorption tower has pipes for inlet bromine-containing air, pipes for inlet circulating air, and pipes for inlet water. At the bottom of the absorption tower, there are outlets for transferring scrubbing water, circulation ports for circulating absorbed air, and outlets for exhaust air.

[0033] Furthermore, a brine pump is installed at the feed end of the oxidation tower, and a chlorine gas pipe and an acidic substance pipe are connected to the pipeline between the brine pump and the oxidation tower.

[0034] The bromide in the brine inside the pipe is acidified and chlorinated to form elemental bromine, and then the brine is sent to the top of the blow-out tower via the oxidation tower.

[0035] Furthermore, the outlet of the absorption tower is provided with a first circulation pipe, and a first circulation pump is provided on the first circulation pipe; the outlet of the elution tank is provided with a second circulation pipe, and a second circulation pump is provided on the second circulation pipe.

[0036] In summary, this application has at least one of the following beneficial technical effects compared with the prior art:

[0037] 1. This invention uses modified activated carbon placed in an absorption tower to adsorb bromine, creating different desorption conditions during detachment, thereby separating impurities and improving the purity of bromine. It eliminates the need for seawater permeation membranes, thus purifying seawater without pretreatment, reducing costs. Furthermore, when further purifying elemental bromine, this invention uses organic substances that do not react with bromine for physical extraction, reducing the use of oxidizing and reducing substances and minimizing environmental pollution.

[0038] 2. The present invention sets up multiple corrugated plates in the absorption tower, and sets up an activated carbon layer on the corrugated plates. When transferring activated carbon, the corrugated plates in contact with the activated carbon layer are pulled away to facilitate the transfer of the activated carbon layer. Then, the activated carbon is taken out and put in through the material exchange door.

[0039] 3. In the modification of activated carbon, the modified material used in this invention is titanium dioxide. Titanium dioxide can effectively improve the adsorption capacity and capacity of activated carbon for bromine, without changing the molecular structure of bromine or causing bromine to undergo chemical reactions. Consequently, it will not undergo reduction and oxidation reactions in subsequent reactions. Furthermore, after improving the adsorption capacity between bromine and activated carbon, it also facilitates the separation of impurities from bromine, resulting in higher purity of bromine in the subsequent process. Attached Figure Description

[0040] Figure 1 This is a flowchart of the concentration process of the present invention;

[0041] Figure 2 This is a process diagram of the concentration apparatus of the present invention;

[0042] Figure 3 This is a structural diagram of the absorption tower of the present invention.

[0043] Figure label:

[0044] 10. Oxidation tower; 11. Brine pump; 12. Chlorine pipe; 13. Acidic substance pipe; 20. Blowout tower; 30. Absorption tower; 31. Corrugated plate; 32. Activated carbon layer; 33. Sand core filter plate; 34. Material changing door; 35. Feed pipe; 36. Water outlet; 37. Circulation port; 38. First circulation pipeline; 39. First circulation pump; 40. Washing tank; 41. Second circulation pipeline; 42. Second circulation pump; 50. Distillation tower. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of the present invention. Figure 1-3 The technical solutions of the embodiments of the present invention will be clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0046] Example 1

[0047] Step 1: After the seawater is dried, a high-concentration brine is formed. The brine is pumped into the feed pipe connected to the oxidation tower. Then, the chlorine gas pipe and the dilute acid pipe are turned on to introduce dilute hydrochloric acid and chlorine into the feed pipe. The mixture is allowed to fully contact and react in the pipe before entering the oxidation tower. The liquid oxidant in the oxidation tower is then sent to the upper part of the blow-out tower through the pipe.

[0048] Step 2: Then, the oxidized brine, i.e. the oxidized liquid, is sprayed from the top of the blow-out tower. At the bottom of the blow-out tower, a blower blows circulating air inward, so that the bromine molecules in the oxidized liquid are carried out by the air. Then, the air containing bromine molecules is discharged from the top of the blow-out tower and enters the absorption tower.

[0049] Step 3: Bromine-containing air enters from the top of the absorption tower and flows downward, passing through the sand core filter plate, modified activated carbon, and corrugated plate inside the absorption tower. Then, it enters the first circulation pipe through the bottom of the absorption tower and is then circulated and absorbed in the upper part of the absorption tower. After multiple cycles, the exhaust air is discharged through the exhaust port at the bottom of the absorption tower.

[0050] The preparation method of modified activated carbon is as follows:

[0051] The activated carbon was heated to 600℃ and then allowed to return to room temperature. It was then immersed in a 0.5 mol / L metatitanic acid solution, followed by the addition of sodium hydroxide for precipitation. The pH value was controlled at 9, and the activated carbon was aged at 150℃ for 24 hours. Finally, the activated carbon was washed with water and dried to obtain modified activated carbon.

[0052] Step 4: Spray the top of the absorption tower with pure water at 10℃ to wash the activated carbon layer. Then let it stand and wait for the water in the activated carbon layer to drain naturally. Open the material exchange door on the side wall of the absorption tower, pull out the corrugated plate, and take out the upper activated carbon layer. Place the activated carbon in the elution tank and use tert-butanol for elution.

[0053] Step 5: Pass tert-butanol containing bromine into a distillation column for distillation. Elemental bromine is discharged at the top of the distillation column, condensed and cooled by a heat exchanger and cooler, and the bromine vapor is condensed into liquid bromine, which is then fed into a bromine-water separation bottle. The crude bromine obtained from the separation bottle is sent back to the distillation column for the next distillation process to obtain the final product bromine.

[0054] Testing showed that the bromine product met the QB / T2021-2022 standard, with bromine ≥99.2%, chlorine ≤0.06%, and non-volatile matter ≤0.06%. After passing through a bromine metering tank, the bromine was transferred to a bromine storage tank. The acidic waste liquid at the bottom of the distillation tower was used to preheat the raw material before being sent to a waste acid storage tank.

[0055] Example 2

[0056] The difference between this embodiment and Embodiment 1 lies in the change of the use of acidic substances and organic extraction solvents. The specific changes are as follows:

[0057] Step 1: After the seawater is dried, a high-concentration brine is formed. The brine is pumped into the feed pipe connected to the oxidation tower. Then, the chlorine gas pipe and the dilute acid pipe are turned on to introduce dilute sulfuric acid and chlorine into the feed pipe. The mixture is allowed to fully contact and react in the pipe before entering the oxidation tower. The liquid oxidant in the oxidation tower is then sent to the upper part of the blow-out tower through the pipe.

[0058] ...

[0059] Step 4: Spray the top of the absorption tower with pure water at 5℃ to wash the activated carbon layer. Then let it stand and wait for the water in the activated carbon layer to drain naturally. Open the material exchange door on the side wall of the absorption tower, pull out the corrugated plate, and remove the upper activated carbon layer. Place the activated carbon in the elution tank and use tetrahydrofuran for elution.

[0060] The remaining steps are the same as in Example 1.

[0061] Testing showed that the bromine product met the QB / T2021-2022 standard, with bromine ≥98.9%, chlorine ≤0.06%, and non-volatile matter ≤0.05%. After passing through a bromine metering tank, the bromine was transferred to a bromine storage tank. The acidic waste liquid at the bottom of the distillation tower was used to preheat the raw material before being sent to a waste acid storage tank.

[0062] Example 3

[0063] The difference between this embodiment and Embodiment 1 lies in the change of the use of acidic substances and organic extraction solvents. The specific changes are as follows:

[0064] Step 1: After the seawater is dried, a high-concentration brine is formed. The brine is pumped into the feed pipe connected to the oxidation tower. Then, the chlorine gas pipe and the dilute acid pipe are turned on to introduce dilute ferric hydroxide and chlorine gas into the feed pipe. The reaction takes place in the pipe and then enters the oxidation tower. The liquid oxidant in the oxidation tower is then sent to the upper part of the blow-out tower through the pipe.

[0065] ...

[0066] Step 4: Spray the top of the absorption tower with pure water at 15℃ to wash the activated carbon layer. Then let it stand and wait for the water in the activated carbon layer to drain naturally. Open the material exchange door on the side wall of the absorption tower, pull out the corrugated plate, and take out the upper activated carbon layer. Place the activated carbon in the elution tank and use 1,2-dimethoxyethane for elution.

[0067] The remaining steps are the same as in Example 1.

[0068] Testing showed that the bromine in the product met the QB / T2021-2022 standard, with bromine ≥99.1%, chlorine ≤0.05%, and non-volatile matter ≤0.08%. The bromine was metered and then transferred to the bromine storage tank. The acidic waste liquid at the bottom of the distillation tower was preheated with the raw material before being sent to the waste acid storage tank.

[0069] Example 4

[0070] The difference between this embodiment and Example 1 is that the organic extraction solvent has been changed. The specific changes are as follows:

[0071] Step 4: Spray the top of the absorption tower with pure water at 10℃ to wash the activated carbon layer. Then let it stand and wait for the water in the activated carbon layer to drain naturally. Open the material exchange door on the side wall of the absorption tower, pull out the corrugated plate, and take out the upper activated carbon layer. Place the activated carbon in the washing tank and wash it with methanol.

[0072] Step 5: Dissolve bromine-containing methanol in water to displace the bromine in the water. Then, pass the bromine-containing water into a distillation column for distillation. Elemental bromine is discharged at the top of the distillation column and condensed and cooled by a heat exchanger and cooler. The bromine vapor is condensed into liquid bromine and enters a bromine-water separation bottle. The crude bromine obtained from the separation bottle is sent back to the distillation column for the next distillation process to obtain the final product, bromine.

[0073] The remaining steps are the same as in Example 1.

[0074] Testing showed that the bromine in the product met the QB / T2021-2022 standard, with bromine ≥98.7%, chlorine ≤0.08%, and non-volatile matter ≤0.09%. The bromine was metered and then transferred to the bromine storage tank. The acidic waste liquid at the bottom of the distillation tower was preheated with the raw material before being sent to the waste acid storage tank.

[0075] Example 5

[0076] The difference between this embodiment and Example 1 is that the organic extraction solvent has been changed. The specific changes are as follows:

[0077] Step 4: Spray the top of the absorption tower with pure water at 10℃ to wash the activated carbon layer. Then let it stand and wait for the water in the activated carbon layer to drain naturally. Open the material exchange door on the side wall of the absorption tower, pull out the corrugated plate, and take out the upper activated carbon layer. Place the activated carbon in the elution tank and use ethanol for elution.

[0078] Step 5: Dissolve bromine-containing ethanol in water to displace the bromine in the water. Then, pass the bromine-containing water into a distillation column for distillation. Elemental bromine is discharged at the top of the distillation column and condensed and cooled by a heat exchanger and cooler. The bromine vapor is condensed into liquid bromine and enters a bromine-water separation bottle. The crude bromine obtained from the separation bottle is sent back to the distillation column for the next distillation process to obtain the final product, bromine.

[0079] The remaining steps are the same as in Example 1.

[0080] Testing showed that the bromine product met the QB / T2021-2022 standard, with bromine ≥98.3%, chlorine ≤0.09%, and non-volatile matter ≤0.07%. The bromine was metered and then transferred to the bromine storage tank. The acidic waste liquid at the bottom of the distillation tower was preheated with the raw material before being sent to the waste acid storage tank.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is that it does not use modified activated carbon to absorb bromine molecules, but instead uses ordinary activated carbon for adsorption.

[0083] Testing revealed that the bromine product met the QB / T2021-2022 standard, with bromine ≥79.2%, chlorine ≤4.42%, and non-volatile matter ≤13.41%. The bromine was metered and then transferred to the bromine storage tank. The acidic waste liquid at the bottom of the distillation tower was preheated with the raw material before being sent to the waste acid storage tank.

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 lies in the water washing temperature in step S4, specifically as follows:

[0086] Step 4: Spray the top of the absorption tower with pure water at 25℃ to wash the activated carbon layer. Then let it stand and wait for the water in the activated carbon layer to drain naturally. Open the material exchange door on the side wall of the absorption tower, pull out the corrugated plate, and remove the upper activated carbon layer. Place the activated carbon in the elution tank and use tert-butanol for elution.

[0087] Testing showed that the bromine product met the QB / T2021-2022 standard, with bromine ≥ 82.2%, chlorine ≤ 3.17%, and non-volatile matter ≤ 8.56%. The bromine was metered and then transferred to the bromine storage tank. The acidic waste liquid at the bottom of the distillation tower was preheated with the raw material before being sent to the waste acid storage tank.

[0088] Comparative Example 3

[0089] The difference between this comparative example and Example 1 is that the modified activated carbon is not modified with titanium dioxide, but with polyethyleneimine. The specific modification method is as follows:

[0090] It is activated at a high temperature of 600℃ to remove any possible impurities;

[0091] Activated carbon was dispersed in deionized water to form a suspension. An appropriate amount of polyethyleneimine solution was added so that PEI molecules could cover the surface of the activated carbon. The pH was adjusted to 8 to promote the binding of PEI with the surface of activated carbon. The suspension was mixed and stirred at room temperature for 6 hours to allow PEI molecules to be fully adsorbed onto the surface of activated carbon.

[0092] Allow the suspension to settle naturally, then discard the supernatant and wash the precipitate with deionized water to remove unbound PEI molecules and other impurities until the outflow is neutral.

[0093] The washed activated carbon precipitate was dried, vacuum dried at 90°C, and activated at 300°C to solidify PEI molecules and further open the pore structure of the activated carbon.

[0094] Testing showed that the bromine in the product met the QB / T2021-2022 standard, with bromine ≥ 68.1%, chlorine ≤ 12.77%, and non-volatile matter ≤ 15.86%. The bromine was metered and then transferred to the bromine storage tank. The acidic waste liquid at the bottom of the distillation tower was preheated with the raw material before being sent to the waste acid storage tank.

[0095] analyze

[0096] Based on the bromine detection data of the finished products of Example 1 and Comparative Example 1, it can be seen that the bromine content of Example 1 is greater than 99.2%, the chlorine content is less than 0.06%, and the non-volatile matter content is also less than 0.06%, while the bromine content of Comparative Example 1 is ≥79.2%, the chlorine content is ≤4.42%, and the non-volatile matter content is ≤13.41%. It can be seen that modifying activated carbon can effectively improve the adsorption capacity of bromine, reduce the content of impurities, and reduce the chlorine content in bromine without using chlorine gas for re-oxidation.

[0097] According to the bromine detection data of the finished products of Example 1 and Comparative Example 2, the bromine content of Comparative Example 2 is ≥82.2, chlorine content is ≤3.17, and non-volatile matter content is ≤8.56. It can be seen that the control of water washing temperature can effectively control the adsorption force between activated carbon and bromine. Low temperature can ensure the adsorption of bromine and activated carbon, facilitate the removal of impurities, and will not introduce other chemical substances.

[0098] Based on the bromine detection data of the finished products of Example 1 and Comparative Example 3, it can be seen that the bromine content of Comparative Example 2 is ≥68.1, chlorine content is ≤12.77, and nonvolatile matter content is ≤15.86. It can be seen that the use of PEI to modify the surface of activated carbon will cause the amino groups on the modified PEI molecules to directly form coordinate bonds with bromine molecules. In water, the bromine molecule will accept a proton to form a Br- ion, and then form a coordinate bond with -NH2 on PEI, consuming bromine molecules and greatly reducing the yield and content of bromine. It is necessary to use chlorine gas for oxidation again, which introduces a large amount of chlorine element.

[0099] The concentration process of Examples 1 to 5 above uses the following concentration apparatus.

[0100] like Figure 2 and Figure 3 As shown, a bromine extraction and concentration device for seawater includes an oxidation tower 10, a blow-out tower 20, an absorption tower 30, an elution tank 40, and a distillation tower 50.

[0101] The outlet of the oxidation tower 10 is connected to the spray inlet at the top of the blow-out tower 20. The lower part of the blow-out tower 20 is provided with an air inlet, and the upper part of the blow-out tower 20 is also provided with an outlet for discharging bromine-containing air and connected to the top inlet of the absorption tower 30. The outlet of the washing tank 40 is connected to the inlet of the distillation tower 50.

[0102] The absorption tower 30 is equipped with multiple layers of corrugated plates 31, and an activated carbon layer 32 is provided on the multiple corrugated plates 31. Modified activated carbon is located inside the activated carbon layer 32. A sand core filter plate 33 is provided above the activated carbon layer 32. A material exchange door 34 is opened on the side wall of the absorption tower 30 near the activated carbon layer 32.

[0103] A mesh plate for placing corrugated plates 31 is provided on the inner wall of the absorption tower 30. An activated carbon layer 32 is placed on the corrugated plates 31. A sand core filter plate 33 is placed above the activated carbon layer 32. The sand core filter plate 33 is fixed to the inner wall of the absorption tower 30 by bolts. A material exchange opening is opened on the wall of the absorption tower 30 at the activated carbon layer 32 location. A material exchange door 34 is hinged to the outer wall of the material exchange opening.

[0104] The absorption tower 30 is equipped with multiple feed pipes 35, and the lower part of the absorption tower 30 is equipped with a water outlet 36 and a circulation port 37.

[0105] These feed pipes 35 are respectively the air inlet pipe for bromine-containing air, the air inlet pipe for circulating air, and the water inlet pipe for low-temperature water washing. The water outlet 36 of the absorption tower 30 is located at the bottom, and the circulation port 37 is located on the lower side wall of the absorption tower 30. The height of the circulation port 37 is greater than the height of the water outlet 36.

[0106] The feed end of the oxidation tower 10 is equipped with a brine pump 11, and a chlorine gas pipe 12 and an acidic substance pipe 13 are connected to the pipeline between the brine pump 11 and the oxidation tower 10.

[0107] The brine pump 11 is used to transfer brine into the pipeline. Valves are installed on both the chlorine pipe 12 and the acidic substance pipe 13 to control the feed.

[0108] The outlet of the absorption tower 30 is provided with a first circulation pipe 38, and a first circulation pump 39 is provided on the first circulation pipe 38. The outlet of the washing tank 40 is provided with a second circulation pipe 41, and a second circulation pump 42 is provided on the second circulation pipe 41.

[0109] The first circulation pipe 38 is used to circulate bromine-containing air, so that the bromine in the air can be completely absorbed by the activated carbon in the absorption tower 30. The second circulation pipe 41 is used to circulate organic extractant, so that the bromine in the modified activated carbon can be completely desorbed and enriched.

[0110] How to use:

[0111] First, seawater is dried to obtain brine. Brine is pumped into the pipeline of oxidation tower 10 using brine pump 11. Then, chlorine gas pipe 12 and acidic substance pipe 13 are turned on to acidify and oxidize the brine. After the reaction is completed in oxidation tower 10, gas-liquid separation is performed. The liquid oxidized substance in oxidation tower 10 is then transferred to the top of blow-out tower 20 for spraying. Air is introduced upward from the bottom of blow-out tower 20 to remove bromine from the brine. The bromine-containing air is piped into the top of absorption tower 30 and then circulated and absorbed by modified activated carbon. Bromine is adsorbed on activated carbon layer 32 and then transferred to washing tank 40. Organic extractant is introduced to desorb bromine. Finally, the bromine-containing organic extractant is distilled in distillation tower 50 to obtain the finished product, elemental bromine.

[0112] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A concentration process for bromine extraction from seawater, characterized in that, The preparation steps include the following: S1. Seawater is dried to form brine, acidic substances are added to generate free bromide ions, and chlorine gas is then passed into the brine to oxidize it, resulting in an oxidized liquid containing bromine molecules. S2. Blow out, using air and oxidizing liquid to convection, separate bromine molecules, and obtain bromine-containing air; S3. Purification and absorption: Using an absorption tower, bromine-containing air is passed through the absorption layer inside the absorption tower. After being absorbed in a cycle, the waste gas is discharged. The absorption layer contains modified activated carbon. S4. Wash activated carbon with water at low temperature, let it stand and dry, and use an organic extractant to remove bromine to obtain a bromine-containing solution; S5. After distilling the bromine-containing solution, bromine of higher purity is obtained; The modifying material for the activated carbon in S3 is titanium dioxide, and the modification method is as follows: The activated carbon was heated to 600℃ and then allowed to return to room temperature. It was then immersed in a 0.1-1.0 mol / L metatitanic acid solution, followed by the addition of sodium hydroxide for precipitation. The pH range was 8-10. The activated carbon was then aged at 100-200℃. Finally, the activated carbon was washed with water and dried to obtain modified activated carbon. The temperature of the low-temperature water washing in S4 is 5-15℃.

2. The concentration process for bromine extraction from seawater as described in claim 1, characterized in that: The acidic substances in S1 are hydrochloric acid and sulfuric acid.

3. The process for concentrating seawater for bromine extraction as claimed in claim 1, wherein: The organic solvent in S4 is methanol, ethanol, tert-butanol, tetrahydrofuran, 1,2-dimethoxyethane, hexane, or heptane.

4. The concentration process for bromine extraction from seawater as claimed in claim 3, characterized by: When the organic extraction solvent is methanol or ethanol, a water washing operation is required before S5 distillation to separate the aqueous phase before distillation.

5. The concentration process according to any one of claims 1 to 4, characterized in that, The concentration process uses a seawater bromine extraction concentration device, including an oxidation tower, a blow-out tower, an absorption tower, an elution tank, and a distillation tower. The absorption tower is equipped with multiple layers of corrugated plates, and an activated carbon layer is provided on the multiple corrugated plates. The modified activated carbon is located in the activated carbon layer. A sand core filter plate is provided above the activated carbon layer. A material replacement door is opened on the side wall of the absorption tower near the activated carbon layer.

6. The concentration process for the extraction of bromine from seawater according to claim 5, characterized by the fact that: The absorption tower is equipped with multiple feed pipes, and the lower part of the absorption tower is equipped with a water outlet and a circulation port.

7. The process for concentrating of seawater for bromine extraction as claimed in claim 5 wherein: A brine pump is installed at the feed end of the oxidation tower, and a chlorine gas pipe and an acidic substance pipe are connected to the pipeline between the brine pump and the oxidation tower.

8. The concentration process for bromine extraction from seawater as described in claim 5, characterized in that: The outlet of the absorption tower is provided with a first circulation pipe, and a first circulation pump is provided on the first circulation pipe. The outlet of the elution tank is provided with a second circulation pipe, and a second circulation pump is provided on the second circulation pipe.

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