Chlorine-free process method for preparing high-quality sodium bromide from bromine-containing brine

Abstract

The invention discloses a process method for preparing high-quality sodium bromide from bromine-containing brine in a chlorine-free manner, and belongs to the technical field of chemical production. Ozone is used as an oxidizing agent to oxidize the bromine-containing brine, and meanwhile, a gaseous membrane method bromine extraction process is coupled to prepare the sodium bromide. The method is a green, safe and efficient high-quality sodium bromide preparation technology, chlorine gas does not need to be used as an oxidizing agent, the safety of the production process is greatly improved, the bromine extraction mother liquor does not contain residual chlorine and is environmentally friendly, the obtained industrial sodium bromide product does not contain chloride ions, the main content of sodium bromide is larger than or equal to 99%, and the quality is superior to various indexes specified in the industrial standard HG / T 3809-2006.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical production, and in particular relates to a process for preparing high-quality sodium bromide from bromine-containing brine without chlorine. Background Art

[0002] Sodium bromide has a wide range of applications. It can be used to prepare photographic films and as a diuretic and sedative in medicine. It is used as a brominating agent in the synthetic fragrance industry and the printing and dyeing industry. It can also be used for trace determination of cadmium. It also has broad application prospects in the field of bromine and compounds. At present, the main production process of high-quality sodium bromide in the industry is: chlorine is used to oxidize bromide ions in low-grade raw material liquid, air blows out bromine element and then absorbs it with an absorbent to achieve enrichment, high-grade absorption liquid is then introduced into chlorine for oxidation, and bromine is resolved under the stripping action of water vapor, condensed and refined to obtain finished bromine, and then the finished bromine is used for reduction reaction with sodium hydroxide and urea to obtain sodium bromide and sodium carbonate, and then evaporated and dried after crystallization and separation to obtain a sodium bromide product that meets the standards. This method has a relatively complicated process, is difficult to operate, and has a low rate of return. At the same time, in the process of preparing finished bromine, it is necessary to rely on chlorine to oxidize bromide ions. Both bromine and chlorine are hazardous chemicals. There are certain safety risks during storage and use, and the residual chlorine contained in the bromine extraction mother liquor also has a certain degree of impact on the environment. In order to prevent and control safety risks in sodium bromide production, improve environmental friendliness and simplify the process flow, it is urgent to develop a green, safe, efficient and high-quality sodium bromide preparation technology.

[0003] CN 106185995 A discloses a method for preparing sodium bromide, including acidification oxidation, air blowing, three alkali absorption, concentration separation and drying of finished products. It omits the steps of preparing finished bromine by distillation and stripping, shortens the process flow, and improves the economy of the production process. However, the process cannot get rid of the dependence on chlorine, and there are safety risks and environmental risks. At the same time, in order to ensure that the oxidation rate reaches more than 95%, the process adopts a chlorine ratio of 110-115% as a control index. Excessive chlorine and liquid mist carry raw material liquid with air blowing into the absorption liquid, producing impurities such as sodium chloride and magnesium chloride, which affects the quality of the sodium bromide product.

[0004] CN20231042702.4 discloses a method for directly preparing sodium bromide in a short process, including acidification oxidation, air blowing, acid absorption, nanofiltration separation and other steps. It combines nanofiltration with air blowing, combines the advantages of both parties, omits secondary chlorine oxidation, distillation, bromine reduction and impurity removal, and shortens the process. However, this process cannot get rid of its dependence on chlorine, and there are safety risks and environmental risks. At the same time, in order to ensure the oxidation rate, the process uses a chlorine addition amount of 100-155%. The sodium chloride impurities produced by excessive chlorine cannot be separated by the nanofiltration process, which ultimately affects the quality of the sodium bromide product.

[0005] CN116161622A discloses a method for preparing bromine from carnallite mother liquor, including the steps of acidification oxidation, air blowing, sodium bromide absorption, distillation separation, etc. This method uses hydrogen peroxide instead of chlorine as an oxidant, and the quality of the obtained industrial bromine product is better than the various indicators of the superior products specified in the industry QB / T2021-1994. The product does not contain chloride ions, and the bromine content can reach more than 99.85%.

[0006] As an efficient green oxidant, ozone has been widely used in the fields of sewage regeneration, food preservation, medical disinfection and injection, semiconductor processing, etc. in recent years. The present invention uses ozone instead of chlorine as an oxidant to oxidize bromine-containing brine. The principle is that ozone in acidic solution 0 =2.07V, second only to fluorine E 0 =2.87V, E in alkaline solution 0 =1.24V, slightly lower than chlorine E 0 =1.36V, higher than bromine E in the whole pH range 0 =1.08V, so it has the basis for oxidizing bromide ions. According to research reports, the ozone and bromide ion system has the following reaction:

[0007] 2Br - +2O 3 →2Br·+3O 2 (1)

[0008] Br·+Br·→Br 2 (2)

[0009] Br 2 +3O 3 +H 2 O→2HBrO+4O 2 (3)

[0010] Br 2 +2HO - →BrO - +Br - +H 2 O(4)

[0011] B O - +2O 3 →BrO 3 - +2O 2 (5)

[0012] Br 2 +Br - →Br 3 - (6)

[0013] In addition, whether it is chlorine or ozone, a gas-liquid two-phase contact reaction occurs when oxidizing bromide ions in the raw material liquid, and the solubility of ozone at room temperature and pressure is only 3-7 mg / L, which is much lower than the solubility of chlorine at room temperature and pressure (2 volumes of chlorine can be dissolved in 1 volume of water). If the equipment and parameters for chlorine oxidation in the traditional process are still used, the bromide ion oxidation reaction rate will be low.

[0014] Therefore, how to strengthen the gas-liquid two-phase mass transfer to increase the reaction rate, while controlling the reaction conditions to avoid the production of bromides other than elemental bromine, and developing a green, safe, and efficient chlorine-free process for preparing high-quality sodium bromide are technical problems that technicians in this field urgently need to solve. Summary of the invention

[0015] In order to solve the above technical problems, the present invention proposes a process for preparing high-quality sodium bromide from bromine-containing brine without chlorine.

[0016] To achieve the above object, the present invention provides the following technical solutions:

[0017] A process for preparing high-quality sodium bromide from bromine-containing brine without chlorine, using ozone as an oxidant to oxidize the bromine-containing brine, and simultaneously coupling a gaseous membrane bromine extraction process to prepare sodium bromide.

[0018] Preferably, the method comprises the following steps:

[0019] (1) After the bromine-containing brine is acidified, ozone is introduced to perform catalytic oxidation, and bromide ions in the bromine-containing brine are rapidly oxidized to elemental bromine under the action of the catalyst to obtain an acidified oxidation liquid and bromine-containing air;

[0020] (2) passing the acidified oxidizing liquid into the tube side of the three-stage gas membrane system in series, and simultaneously passing the absorbing liquid into the shell side of the three-stage gas membrane system in series in reverse, so that the bromine element diffuses from the acidified oxidizing liquid into the absorbing liquid through the membrane pores to achieve separation and absorption of the bromine element, thereby obtaining a first absorption completion liquid and a bromine extraction mother liquor;

[0021] (3) subjecting the first absorption completed liquid to crystallization separation, washing and drying to obtain a sodium bromide product.

[0022] Preferably, the bromine-containing brine in step (1) comprises desalinated brine or landed seawater, and the bromide ion concentration is 50-100 mg / L.

[0023] Beneficial effects: As the reserves and grade of underground brine bromine resources in my country continue to decline, actively developing and utilizing bromine resources in seawater is an inevitable choice to ensure the stability of my country's bromine supply. Desalinated brine or seawater onshore has the advantages of clean water quality, low scaling, large and stable supply, and is the preferred choice for extracting bromine from seawater.

[0024] More preferably, the acidification treatment is to adjust the pH value of the bromine-containing brine to 1-1.8 using sulfuric acid; if the pH is too high, there will be more side reactions in the oxidation process, such as the spontaneous hydrolysis reaction of bromine in water to 3Br 2 +3H 2 O→BrO 3 - +5Br - +6H + , bromate is easily generated, resulting in a low yield of bromine, and hydrogen ions can inhibit the reaction process; too low pH causes waste of acid and increases operating costs.

[0025] Preferably, the total amount of ozone introduced in step (1) is 105-115% of the theoretical amount of the reaction, and the ozone is introduced in three stages, with the amount introduced in the first stage being 40-50% of the total amount, and the remaining two stages being introduced in equal amounts.

[0026] Beneficial effects: Too low an ozone intake results in a low yield of elemental bromine; too high an ozone intake results in a waste of ozone and increases the processing pressure of the ozone tail gas destructor.

[0027] More preferably, the ozone generator adopts a constant high-voltage spike pulse discharge mode to highly concentrate the ozone ionization energy, improve the utilization rate of electric energy, and reduce production energy consumption; the high-power power supply is controlled by diodes for multiple rectification to improve the power factor.

[0028] Preferably, during the catalytic oxidation process in step (1), a supported manganese-based oxide catalyst M is used. x Mn y O z / Al 2 O 3 , wherein x, y, z are real numbers, and M is a combination of one or more of Fe, Cd, Co, Ni, Cu and Zr.

[0029] Beneficial effect: The above catalyst can convert ozone in aqueous solution into hydroxyl radicals (·OH) with higher oxidation potential. The reaction rate of hydroxyl radicals with most organic matter is about 10 6 ~10 10 M -1 ·s -1 The reaction rate between ozone and organic matter is nearly 7 orders of magnitude higher, which greatly improves the oxidation efficiency of bromide ions. Metal oxide catalysts generally follow the free radical mechanism. Introducing other metals into manganese-based catalysts and utilizing the synergistic effect between the redox cycles of different metals can further improve the activity of catalytic ozone decomposition. At the same time, through the complexation of O on the surface of oxide hydroxyl groups, 3 Accelerate its decomposition to produce OH. By adding the catalyst, the residence time of the system in the catalytic oxidation tank is greatly shortened, reducing the equipment footprint and investment.

[0030] More preferably, the particle size of the supported manganese-based oxide catalyst is 10-20 mm, and the loading amount is 0.3-12 g / m 3 .

[0031] Beneficial effects: Too little catalyst addition leads to a low reaction rate; too much catalyst addition increases production and operation costs; catalysts with suitable particle sizes are driven by the upward flow rate of the acidified raw liquid and exist in a fluid state in the bed, which improves the reaction contact efficiency. Filters are provided above and below the bed to prevent the catalyst from being lost with the acidified raw liquid; too small a particle size requires too dense a filter, and the flow resistance of the acidified raw liquid is too great; too large a particle size means that the catalyst particles cannot be in a fluid state in the bed.

[0032] Preferably, the catalytic oxidation process uses a baffle-type catalytic oxidation device, including a first-stage oxidation chamber for raw material liquid, a second-stage oxidation chamber for raw material liquid, a third-stage oxidation chamber for raw material liquid and a gas-liquid separation chamber connected in series in sequence;

[0033] The first stage oxidation chamber, the second stage oxidation chamber and the third stage oxidation chamber of the raw liquid respectively include a catalytic bed, and ozone is introduced below the catalytic bed through the first stage ozone adding pipe, the second stage ozone adding pipe and the third stage ozone adding pipe respectively;

[0034] The gas-liquid separation chamber includes a wire mesh demister.

[0035] Beneficial effects: Due to the low solubility of ozone, the three-stage oxidation chambers are connected in series and the ozone is added to the acidified raw liquid in three stages to ensure the concentration of ozone in the liquid phase and improve the reaction efficiency. The addition of the catalyst converts ozone into hydroxyl radicals (·OH) with a higher oxidation potential, thereby improving the reaction efficiency. The design of the gas-liquid separation chamber can ensure the stable operation of the subsequent gas membrane system.

[0036] Preferably, the bromine-containing air in step (1) is subjected to absorption of bromine by an absorption liquid in a tail gas absorption tower to obtain a second absorption completion liquid and tail gas containing a very small amount of bromine;

[0037] The second absorption completion liquid is combined with the first absorption completion liquid for treatment;

[0038] The tail gas containing extremely small amounts of bromine is absorbed by alkaline solution in the tail gas purification tower, and then enters the ozone tail gas destructor to remove ozone, so that the gas meets the emission standards.

[0039] Beneficial effect: The air introduced into the catalytic oxidation tank along with the ozone will carry a portion of the bromine element out of the catalytic oxidation tank. By setting up tail gas absorption towers, tail gas purification towers, ozone tail gas destroyers and other devices, the bromine element carried in the air can be recovered and the unreacted ozone can be destroyed, which can prevent environmental pollution and realize the utilization of bromine resources.

[0040] Preferably, the absorption liquid is a mixed solution of caustic soda and urea, wherein the mass concentration of caustic soda is 8-18%, and the mass concentration of urea is 2-5%.

[0041] Beneficial effect: The mixed solution of caustic soda and urea in the present invention can react with bromine to produce the following reaction: 2 +6NaOH+(NH 2 ) 2 CO→6NaBr+5H 2 O+N 2 +CO 2 , directly obtain high-quality sodium bromide absorption liquid, which is convenient for obtaining high-quality sodium bromide products. If the absorption liquid concentration is too low, the sodium bromide content in the absorption liquid will be low, and the amount of water evaporated during subsequent crystallization will be large; if the absorption liquid concentration is too high, there is a risk of crystallization blocking the gas membrane pores.

[0042] Preferably, the first absorption completion liquid and the second absorption completion liquid are continuously circulated until the pH of the absorption liquid is 10-11, at which time the sodium bromide content is 100-300 g / L.

[0043] Beneficial effects: Bromine enrichment is achieved by continuous circulation of the absorption liquid, and the pH control method is simple and easy.

[0044] Preferably, the gaseous membrane system in step (2) is constructed using an 8-inch polyvinylidene fluoride hollow fiber membrane component having super hydrophobicity obtained by soaking and modifying with a silane coupling agent for 24 hours.

[0045] Beneficial effects: The present invention introduces low surface energy chemicals on the membrane surface to reduce the contact area between water droplets and the membrane surface, thereby forming a super-hydrophobic effect. This treatment can not only improve the hydrophobicity of the membrane, but also enhance its oxidation resistance, acid and alkali resistance, aging resistance and other properties, so that the membrane material has better stability and durability in harsh environments.

[0046] Preferably, in the three-stage gas membrane system connected in series in step (2), the bromide ion concentration of the bromine extraction mother liquor obtained by the first-stage gas membrane system is 16-30 mg / L, the bromide ion concentration of the bromine extraction mother liquor obtained by the second-stage gas membrane system is 5-11 mg / L, and the bromide ion concentration of the bromine extraction mother liquor obtained by the third-stage gas membrane system is 3-7 mg / L.

[0047] Beneficial effects: The above process can balance resource recovery rate and equipment investment, and selects a three-stage gas membrane system to fully recover bromine resources (recovery rate 95%) while reducing membrane equipment investment and land occupation.

[0048] Preferably, the flow rate of the acidified oxidizing liquid in the tube in step (2) is 0.5-1.5m 3 / h;

[0049] The absorption liquid flow rate in the shell side is 1.0-2.5m 3 / h.

[0050] The processing efficiency of the gas membrane system can be ensured at the above flow rate.

[0051] Preferably, the bromine extraction mother liquor in step (2) is neutralized with sodium carbonate produced by crystallization separation in step (3) to a pH of 6-7 and then discharged.

[0052] Beneficial effects: The present invention makes full use of the sodium carbonate by-product of the system to recover the bromine extraction mother liquor, thereby realizing the recycling of resources.

[0053] Compared with the prior art, the present invention has the following advantages and technical effects:

[0054] The present invention is a green, safe, and efficient high-quality sodium bromide preparation technology. It does not need to use chlorine as an oxidant. The one-step preparation of sodium bromide by coupling the gas membrane method does not require the preparation of industrial bromine and then reacting to obtain the sodium bromide product. The entire production process does not use or produce hazardous chemicals such as chlorine and bromine, which greatly improves the safety of the production process; the bromine extraction mother liquor does not contain residual chlorine and is environmentally friendly; the obtained industrial sodium bromide product does not contain chloride ions, and the main content of sodium bromide is ≥99%, which is better than the various indicators specified in the industry standard HG / T3809-2006. The process flow is simple, no steam is required, and the production cost is low. In addition, the present invention achieves efficient utilization of bromine resources in raw materials while improving production safety by coupling the advantages of ozone oxidation, air blowing method, and gas membrane method, and the comprehensive utilization rate of bromide ions can reach more than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0056] Figure 1 The process flow chart of the present invention is to prepare high-quality sodium bromide from bromine-containing brine without chlorine;

[0057] Figure 2 It is a schematic diagram of the structure of the ozone catalytic oxidation tank device in the present invention;

[0058] The labels are: 1. ozone first-stage addition pipe, 2. ozone second-stage addition pipe, 3. ozone third-stage addition pipe, 4. catalyst bed, 5. aeration component, 6. raw material liquid first-stage oxidation chamber, 7. raw material liquid second-stage oxidation chamber, 8. raw material liquid third-stage oxidation chamber, 9. gas-liquid separation chamber, 10. wire mesh demister. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources;

[0062] The brine is taken from the membrane (RO) desalination byproduct with a salt content of 6%;

[0063] The supported iron-manganese composite oxide catalyst used in the embodiment of the present invention is a supported iron-manganese composite oxide prepared by a hydrothermal method using materials such as ferrous chloride, manganese chloride, sodium hydroxide, and γ-alumina. Its composition can be expressed as Fe 0.2 Mn 0.8 O 2 / Al 2 O 3 .

[0064] The catalytic oxidation process in the embodiment of the present invention adopts a baffle-type catalytic oxidation device, such as Figure 2 As shown, it comprises a first-stage oxidation chamber 6 for raw material liquid, a second-stage oxidation chamber 7 for raw material liquid, a third-stage oxidation chamber 8 for raw material liquid and a gas-liquid separation chamber 9 which are connected in series in sequence;

[0065] The first stage oxidation chamber 6, the second stage oxidation chamber 7 and the third stage oxidation chamber 8 of the raw liquid respectively include a catalytic bed 4, and ozone is introduced under the catalytic bed through the first stage ozone adding pipe 1, the second stage ozone adding pipe 2 and the third stage ozone adding pipe 3, and contacts the catalytic bed after aeration by the aeration assembly;

[0066] The gas-liquid separation chamber 9 includes a wire mesh demister 10 .

[0067] The equipment increases the gas-water cross-sectional flow rate, allowing bromine-containing brine and ozone to contact more frequently and strengthen gas-liquid mass transfer. The residence time of the raw material liquid in the baffled catalytic oxidation tank is controlled at 60-100s; if the residence time is too short, the bromine yield is low; if the residence time is too long, the oxidation tank volume required is too large, increasing the investment cost.

[0068] The tail gas absorption tower in the embodiment of the present invention adopts a glass fiber reinforced plastic packed tower, and the empty tower gas velocity is controlled at 0.8-1.2m / s to ensure the absorption efficiency. The tower is filled with PP or PTFE stepped rings, flower balls and other random packings.

[0069] Example 1

[0070] A process for preparing high-quality sodium bromide from bromine-containing brine without chlorine, such as Figure 1 As shown, the following steps are included:

[0071] (1) Desalinated brine (bromine-containing brine) with a bromide ion content of about 82 mg / L is used as a raw material, sulfuric acid is added for acidification, and the pH is adjusted to 1.0; the air compressor is started to blow air into the ozone generator, the power pulse density is adjusted, and the ozone generator is controlled to pass ozone according to 115% of the theoretical calculated amount of the reaction;

[0072] (2) Figure 2 As shown, the catalytic oxidation tank is divided into three areas (first stage oxidation chamber 6 for raw material liquid, second stage oxidation chamber 7 for raw material liquid, and third stage oxidation chamber 8 for raw material liquid). The catalyst bed 4 is filled with a total weight of 12 g / m 3 The supported iron-manganese composite oxide catalyst is used to control the liquid feed flow rate so that its residence time in the catalytic oxidation tank is maintained at about 60s. At this time, the main reaction occurring in the oxidation tank is 2Br - +2O 3 →2Br·+3O 2 and Br·+Br·→Br 2 ; Very small amount of BrO 3 - In a strong acidic system, Br - Disproportionation reaction occurs 5Br - +BrO 3 - +6H + →3Br 2 +3H 2 O. The bromine ion content of the liquid outlet of the gas-liquid separation chamber 9 of the catalytic oxidation tank was sampled and tested to be 2.1 mg / L, and the calculated oxidation rate was 97.4%, and an acidified oxidation liquid was obtained.

[0073] (3) 8-inch polyvinylidene fluoride hollow fiber membrane was modified by soaking in silane coupling agent for 24 hours to make it super hydrophobic, and then the polyvinylidene fluoride hollow fiber membrane module after soaking was used to build a three-stage series gas membrane system; the acidified oxidation liquid discharged from the catalytic oxidation tank in step (2) was heated to 1.0 m 3 / h flow into the tube side of the primary gas membrane system, the bromine extraction mother liquor obtained in the primary gas membrane system enters the tube side of the secondary gas membrane system, the bromine extraction mother liquor obtained in the secondary gas membrane system enters the tube side of the tertiary gas membrane system, and the bromine extraction mother liquor obtained in the tertiary gas membrane system enters the neutralization treatment system; prepare a circulating absorption liquid with a sodium hydroxide mass concentration of 16% and a urea mass concentration of 4.6%, and pass the absorption liquid at a rate of 2.5m 3 / h flow rate into the shell side of the three-stage gas membrane system, the absorption liquid obtained from the three-stage gas membrane system enters the shell side of the two-stage gas membrane system, the absorption liquid obtained from the two-stage gas membrane system enters the shell side of the one-stage gas membrane system, the absorption liquid obtained from the one-stage gas membrane system enters the absorption liquid circulation tank, and then enters the shell side of the three-stage gas membrane system again after being pressurized by a pump, and the above steps are repeated until the absorption liquid is continuously enriched to about pH=10, and the sodium bromide content therein is detected to be 262g / L, and the absorption completed liquid is obtained; the bromide ion concentration at the outlet of the tube side of each stage of the gas membrane system is sampled and detected, wherein the bromide ion concentration of the first-stage bromine extraction mother liquor is 29.6mg / L, the bromide ion concentration of the second-stage bromine extraction mother liquor is 10.2mg / L, and the bromide ion concentration of the third-stage bromine extraction mother liquor is 4.1mg / L, and the comprehensive utilization rate of bromide ions reaches more than 95%.

[0074] (4) The absorption completed liquid obtained in step (3) is sent to a crystallization separation system, in which the absorption completed liquid is subjected to triple-effect evaporation to precipitate sodium carbonate, and sodium bromide is obtained after cooling and crystallization; the precipitated sodium carbonate is sent to a neutralization treatment system to neutralize the bromine extraction mother liquor, and the bromine extraction mother liquor is discharged after the pH value is restored to 6.9; the cold-precipitated crystallized sodium bromide is washed and dried to obtain a product, and after analysis and testing, the quality of the obtained industrial sodium bromide product is better than the various indicators specified in the industry standard HG / T 3809-2006, the product does not contain chloride ions, and the main content of sodium bromide is ≥ 99% or more.

[0075] (5) Tail gas treatment: In step (2), while the acidified oxidizing liquid is obtained in the gas-liquid separation chamber 9, bromine-containing air is discharged, i.e., the air blown in by the air compressor carries a trace amount of ozone and free bromine, and the bromine-containing air enters the tail gas absorption tower; a circulating absorption liquid with a sodium hydroxide mass concentration of 16% and a urea mass concentration of 4.6% is prepared, and the bromine-containing air is circulated and sprayed in the tail gas absorption tower to absorb the bromine therein. At this time, the main reaction occurring in the absorption tower is 3Br 2 +6NaOH+(NH 2 ) 2 CO→6NaBr+CO 2 +N 2 +5H 2O, continuously circulates and absorbs until the pH of the absorption liquid is about 10, and the sodium bromide content is detected to be 259g / L, and then sent to the crystallization separation system; at the same time, the tail gas after absorption also contains a very small amount of bromine, which is further absorbed by the fresh alkali solution in the purification tower with the tail gas, and the tail gas containing trace ozone is obtained, which is further sent to the ozone tail gas destructor to remove ozone, and finally discharged into the high altitude.

[0076] Example 2

[0077] A process for preparing high-quality sodium bromide from bromine-containing brine without chlorine, comprising the following steps:

[0078] (1) Natural seawater (bromine-containing brine) is used as raw material, and its bromide ion content is about 53 mg / L. Sulfuric acid is added for acidification and the pH is adjusted to 1.5; the air compressor is started to blow air into the ozone generator, and the power pulse density is adjusted to control the ozone generator to pass ozone according to 105% of the theoretical calculated amount of the reaction;

[0079] (2) The catalytic oxidation tank is divided into three areas and filled with a total weight of 0.6 g / m 3 The supported iron-manganese composite oxide catalyst was used to control the flow rate of the liquid feed so that its residence time in the catalytic oxidation tank was maintained at about 60 seconds. The bromide ion content at the outlet of the catalytic oxidation tank was sampled and tested to be 2.6 mg / L, and the calculated oxidation rate was 95.1%, and an acidified oxidation liquid was obtained.

[0080] (3) 8-inch polyvinylidene fluoride hollow fiber membrane was modified by soaking in silane coupling agent for 24 hours to make it super hydrophobic, and then the polyvinylidene fluoride hollow fiber membrane module after soaking was used to build a three-stage series gas membrane system; the acidified oxidation liquid discharged from the catalytic oxidation tank in step (2) was heated to 0.8 m 3 / h flow into the tube side of the primary gas membrane system, the bromine extraction mother liquor obtained in the primary gas membrane system enters the tube side of the secondary gas membrane system, the bromine extraction mother liquor obtained in the secondary gas membrane system enters the tube side of the tertiary gas membrane system, and the bromine extraction mother liquor obtained in the tertiary gas membrane system enters the neutralization treatment system; prepare a circulating absorption liquid with a sodium hydroxide mass concentration of 8% and a urea mass concentration of 2.3%, and pass the absorption liquid at a rate of 1.5m 3 / h flow rate is passed into the shell side of the three-stage gas membrane system to absorb the bromide ions in the acidified oxidizing liquid in the tube side, wherein the absorption liquid obtained from the three-stage gas membrane system enters the shell side of the two-stage gas membrane system, the absorption liquid obtained from the two-stage gas membrane system enters the shell side of the one-stage gas membrane system, the absorption liquid obtained from the one-stage gas membrane system enters the absorption liquid circulation tank, and then enters the shell side of the three-stage gas membrane system again after being pressurized by a pump, and the above steps are repeated until the absorption liquid is continuously enriched to about pH=11, and the sodium bromide content therein is detected to be 127g / L, to obtain the absorption completed liquid; the bromide ion concentration at the tube side outlet of each stage of the gas membrane system is sampled and detected, wherein the bromide ion concentration of the first-stage bromine extraction mother liquor is 16.4mg / L, the bromide ion concentration of the second-stage bromine extraction mother liquor is 5.7mg / L, the bromide ion concentration of the third-stage bromine extraction mother liquor is 3.2mg / L, and the comprehensive utilization rate of bromide ions reaches 94%.

[0081] (4) The absorption completed liquid obtained in step (3) is sent to a crystallization separation system, in which the absorption completed liquid is subjected to triple-effect evaporation to precipitate sodium carbonate, which is cooled and crystallized to obtain sodium bromide; the precipitated sodium carbonate is sent to a neutralization treatment system to neutralize the bromine extraction mother liquor, and the bromine extraction mother liquor is discharged after the pH value is restored to 6.6; the cold-precipitated crystallized sodium bromide is washed and dried to obtain a product, and after analysis and testing, the quality of the obtained industrial sodium bromide product is better than the various indicators specified in the industry standard HG / T 3809-2006, the product does not contain chloride ions, and the main content of sodium bromide is ≥ 99% or more.

[0082] (5) Tail gas treatment: In step (2), while obtaining the acidified oxidizing liquid, bromine-containing air is discharged, i.e., the air blown in by the air compressor carries a trace amount of ozone and free bromine, and the bromine-containing air enters the tail gas absorption tower; a circulating absorption liquid with a sodium hydroxide mass concentration of 8% and a urea mass concentration of 2.3% is prepared, and the bromine-containing air is circulated and sprayed in the tail gas absorption tower to absorb the bromine therein, and the bromine is continuously circulated and absorbed until the pH value of the absorption liquid is about 11, and the sodium bromide content is detected to be 125g / L, and then sent to the crystallization separation system; at the same time, the tail gas after absorption also contains a very small amount of bromine, which is further absorbed by the tail gas into the purification tower and absorbed by the fresh alkali solution, and the tail gas containing a trace amount of ozone is obtained, which is further sent to the ozone tail gas destructor to remove ozone, and finally discharged into the high altitude.

[0083] Example 3

[0084] A process for preparing high-quality sodium bromide from bromine-containing brine without chlorine, comprising the following steps:

[0085] (1) Using natural seawater mixed with desalinated concentrated seawater as raw material (bromine-containing brine), the bromide ion content of which is about 68 mg / L, sulfuric acid is added for acidification, and the pH is adjusted to 1.8; starting the air compressor, blowing air into the ozone generator, adjusting the power pulse density, and controlling the ozone generator to pass ozone according to 110% of the theoretical calculated amount of the reaction;

[0086] (2) The catalytic oxidation tank is divided into three areas and filled with a total weight of 1.8 g / m 3 The supported iron-manganese composite oxide catalyst was used to control the flow rate of the liquid feed so that its residence time in the catalytic oxidation tank was maintained at about 70 seconds. The bromide ion content at the outlet of the catalytic oxidation tank was sampled and tested to be 5.4 mg / L, and the calculated oxidation rate was 92.1%, and an acidified oxidation liquid was obtained.

[0087] (3) 8-inch polyvinylidene fluoride hollow fiber membrane was modified by soaking in silane coupling agent for 24 hours to make it super hydrophobic, and then the polyvinylidene fluoride hollow fiber membrane module after soaking was used to build a three-stage series gas membrane system; the acidified oxidation liquid discharged from the catalytic oxidation tank in step (2) was heated to 1.5 m 3 / h flow into the tube side of the primary gas membrane system, the bromine extraction mother liquor obtained in the primary gas membrane system enters the tube side of the secondary gas membrane system, the bromine extraction mother liquor obtained in the secondary gas membrane system enters the tube side of the tertiary gas membrane system, and the bromine extraction mother liquor obtained in the tertiary gas membrane system enters the neutralization treatment system; prepare a circulating absorption liquid with a sodium hydroxide mass concentration of 10% and a urea mass concentration of 2.8%, and pass the absorption liquid at a rate of 1.5m 3 / h flow rate is passed into the shell side of the three-stage gas membrane system, the absorption liquid obtained from the three-stage gas membrane system enters the shell side of the two-stage gas membrane system, the absorption liquid obtained from the two-stage gas membrane system enters the shell side of the one-stage gas membrane system, the absorption liquid obtained from the one-stage gas membrane system enters the absorption liquid circulation tank, and then enters the shell side of the three-stage gas membrane system again after being pressurized by a pump, and the above steps are repeated until the absorption liquid is continuously enriched to about pH=10, and the sodium bromide content therein is detected to be 182g / L, to obtain absorption completed liquid; sampling is taken to detect the bromide ion concentration at the tube side outlet of each stage of the gas membrane system, wherein the bromide ion concentration of the first-stage bromine extraction mother liquor is 27.2mg / L, the bromide ion concentration of the second-stage bromine extraction mother liquor is 10.7mg / L, the bromide ion concentration of the third-stage bromine extraction mother liquor is 6.4mg / L, and the comprehensive utilization rate of bromide ions reaches 90.5%.

[0088] (4) The absorption completed liquid obtained in step (3) is sent to a crystallization separation system, in which the absorption completed liquid is subjected to triple-effect evaporation to precipitate sodium carbonate, which is cooled and crystallized to obtain sodium bromide; the precipitated sodium carbonate is sent to a neutralization treatment system to neutralize the bromine extraction mother liquor, and the bromine extraction mother liquor is discharged after the pH value is restored to 7.0; the cold-precipitated crystallized sodium bromide is washed and dried to obtain a product, and after analysis and testing, the quality of the obtained industrial sodium bromide product is better than the various indicators specified in the industry standard HG / T 3809-2006, the product does not contain chloride ions, and the main content of sodium bromide is ≥ 99% or more.

[0089] (5) Tail gas treatment: In step (2), while obtaining the acidified oxidizing liquid, bromine-containing air is discharged, i.e., the air blown in by the air compressor carries a trace amount of ozone and free bromine, and the bromine-containing air enters the tail gas absorption tower; a circulating absorption liquid with a sodium hydroxide mass concentration of 10% and a urea mass concentration of 2.8% is prepared, and the bromine-containing air is circulated and sprayed in the tail gas absorption tower to absorb the bromine therein, and the bromine is continuously circulated and absorbed until the pH value of the absorption liquid is about 10, and the sodium bromide content is detected to be 177 g / L, and then sent to the crystallization separation system; at the same time, the tail gas after absorption also contains a very small amount of bromine, which is further absorbed by the tail gas into the purification tower and absorbed by the fresh alkali solution, and the tail gas containing a trace amount of ozone is obtained, which is further sent to the ozone tail gas destructor to remove ozone, and finally discharged into the high altitude.

[0090] Comparative Example 1

[0091] A process for preparing high-quality sodium bromide from bromine-containing brine without chlorine, which is different from Example 1 in that the catalytic oxidation tank in step (2) only includes one oxidation chamber.

[0092] Technical effect: Total weight 12g / m 3 The supported iron-manganese composite oxide catalyst is placed in the bed of the first oxidation chamber, and the theoretically calculated amount of 115% ozone is also introduced into the first oxidation chamber at one time; after the residence time is maintained at 60s, the liquid outlet bromide ion content of the gas-liquid separation chamber 9 of the catalytic oxidation tank is sampled and tested to be 18.4mg / L, and the calculated oxidation rate is 77.56%. Only bromine oxidized to a single substance can enter the absorption liquid through the gaseous membrane pores, and such a low oxidation rate will affect the utilization rate of bromine resources.

[0093] Comparative Example 2

[0094] A process for preparing high-quality sodium bromide from chlorine-free brine containing bromine, which is different from Example 1 in that a three-stage gas membrane system in series is not used in step (3), but is replaced by a gas membrane system comprising only one stage.

[0095] Technical effect: At this time, the oxidation rate of the acidified oxidation liquid is 97.4%, with a 1.0m 3 / h flow rate into the first-stage gas membrane system, prepare a circulating absorption liquid with a sodium hydroxide mass concentration of 16% and a urea mass concentration of 4.6%, and pass the absorption liquid at a rate of 2.5m 3 / h flow rate into the shell side of the primary gas membrane system, then pumped and continuously enriched to pH = 10, the sodium bromide content was detected to be 260g / L, and the absorption completed liquid was obtained; the bromide ion concentration of the primary bromine extraction mother liquor was sampled and tested to be 28.7mg / L, and the comprehensive utilization rate of bromide ions was only 65%, which affects the utilization rate of bromine resources.

[0096] Comparative Example 3

[0097] A process for preparing high-quality sodium bromide from chlorine-free brine containing bromine, which is different from Example 1 in that the absorption liquid is replaced by a sodium hydroxide absorption liquid with a mass concentration of 16%.

[0098] Technical effect: The reaction that occurs at this time is 3Br 2 +6NaOH→5NaBr+NaBrO 3 +3H 2 O, bromine element is converted into a mixture of sodium bromide and sodium bromate in the absorption liquid, and the two are difficult to be completely separated by means of regulating crystallization. The mass fraction of sodium bromate entrained in the obtained industrial sodium bromide product is 0.8%, which is much higher than the industry standard HG / T 3809-2006 that stipulates that the content of bromate (calculated as bromate ion) of superior grade products shall not exceed 0.003%, and the content of bromate (calculated as bromate ion) of first-grade products shall not exceed 0.005%.

[0099] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A process for preparing high-quality sodium bromide from bromine-containing brine without chlorine, characterized in that: Ozone is used as an oxidant to oxidize bromine-containing brine, and a gaseous membrane bromine extraction process is coupled to produce sodium bromide.

2. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 1, characterized in that: The following steps are involved: (1) introducing ozone into the bromine-containing brine after acidification for catalytic oxidation to obtain an acidified oxidation liquid and bromine-containing air; (2) passing the acidified oxidizing liquid into the tube side of the three-stage gas membrane system in series, and simultaneously passing the absorbing liquid into the shell side of the three-stage gas membrane system in series in reverse, so that the bromine element diffuses from the acidified oxidizing liquid into the absorbing liquid through the membrane pores to achieve separation and absorption of the bromine element, thereby obtaining a first absorption completion liquid and a bromine extraction mother liquor; (3) subjecting the first absorption completed liquid to crystallization separation, washing and drying to obtain a sodium bromide product.

3. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 2, characterized in that: The bromine-containing brine in step (1) includes desalinated concentrated brine or landed seawater, and the bromide ion concentration is 50-100 mg / L.

4. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 2, characterized in that: The total amount of ozone introduced in step (1) is 105-115% of the theoretical amount of the reaction, and the ozone is introduced in three stages, with the first stage introducing 40-50% of the total amount, and the remaining two stages introducing equal amounts.

5. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 2, characterized in that: In the catalytic oxidation process described in step (1), a supported manganese-based oxide catalyst M is used. x Mn y O z / Al2O3, where x, y, and z are real numbers, and M is a combination of one or more of Fe, Cd, Co, Ni, Cu, and Zr.

6. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 2, characterized in that: The bromine-containing air in step (1) absorbs the bromine element in a tail gas absorption tower using an absorption liquid to obtain a second absorption completion liquid and tail gas containing a very small amount of bromine; The second absorption completion liquid is combined with the first absorption completion liquid for treatment; The tail gas containing extremely small amounts of bromine is absorbed by alkaline solution in the tail gas purification tower, and then enters the ozone tail gas destroyer to remove ozone, so that the gas meets the emission standards.

7. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 2 or 6, characterized in that: The absorption liquid is a mixed solution of caustic soda and urea, wherein the mass concentration of caustic soda is 8-18%, and the mass concentration of urea is 2-5%.

8. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 2 or 6, characterized in that: The first absorption completion liquid and the second absorption completion liquid are continuously circulated until the pH of the absorption liquid is 10-11, at which time the sodium bromide content is 100-300 g / L.

9. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 2, characterized in that: The flow rate of the acidified oxidizing liquid in the tube in step (2) is 0.5-1.5m 3 / h; The absorption liquid flow rate in the shell side is 1.0-2.5m 3 / h.

10. The process for preparing high-quality sodium bromide from bromine-containing brine without chlorine according to claim 2, characterized in that: The bromine extraction mother liquor in step (2) is neutralized with sodium carbonate produced by crystallization separation in step (3) to a pH of 6-7 and then discharged.

Images