Process for preparing high-quality sodium bromide from bromine-containing brine without chlorine

Abstract

The application discloses a process method for preparing high-quality sodium bromide from bromine-containing brine without chlorine, and belongs to the technical field of chemical production. The process method uses ozone as an oxidant to oxidize bromine-containing brine, and simultaneously uses a gaseous membrane method to prepare sodium bromide. The process method is green, safe and efficient, and can greatly improve the safety of the production process without using chlorine as an oxidant. The bromine extraction mother liquor is environmentally friendly and does not contain residual chlorine. The obtained industrial sodium bromide product does not contain chlorine ions, the main content of sodium bromide is greater than 99%, and the quality is better than the indexes specified in the industry standard HG / T 3809-2006.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical production, and particularly relates to a process method for preparing high-quality sodium bromide from bromine-containing brine without chlorine. BACKGROUND

[0002] Sodium bromide is widely used in the preparation of photographic film, as a diuretic and a sedative in medicine, as a brominating agent in the synthetic perfume industry and the printing and dyeing industry, and can 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 as follows: bromide ions in low-grade raw material liquid are oxidized by chlorine gas, elemental bromine is blown out by air, and then absorbed by an absorbent to achieve enrichment. High-grade absorption liquid is introduced into chlorine gas to be oxidized, and bromine is stripped under the action of water vapor. The product bromine is obtained by condensation and purification. Sodium bromide and sodium carbonate are obtained by reduction reaction of the product bromine with sodium hydroxide and urea. After crystallization and separation, the sodium bromide product meets the standard. This method is relatively cumbersome, difficult to control, and has a low return rate. At the same time, the preparation of product bromine needs to rely on the oxidation of bromide ions by chlorine gas. Both bromine and chlorine gas are dangerous chemicals, which have certain safety risks in storage and use. Moreover, the residual chlorine in the bromine extraction mother liquor has a certain impact on the environment. In order to prevent and control the safety risks in the production of sodium bromide, improve the environmental friendliness, and simplify the process flow, it is urgent to develop a green, safe and efficient preparation technology for high-quality sodium bromide.

[0003] CN 106185995 A discloses a method for preparing sodium bromide, which includes the steps of acidification and oxidation, air blowing, three times of alkali absorption, concentration and separation, and drying of the product. The method eliminates the step of preparing product bromine by distillation and stripping, shortens the process flow, and improves the economy of the production process. However, the method cannot get rid of the dependence on chlorine gas, 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 method uses a chlorine addition amount of 110-115% as a control index. Excessive chlorine gas and liquid mist entrain raw material liquid, which is blown out by air into the absorption liquid, producing impurities such as sodium chloride and magnesium chloride, and affecting the quality of sodium bromide product.

[0004] CN20231042702.4 discloses a method for directly preparing sodium bromide in a short process, which includes the steps of acidification and oxidation, air blowing, acid absorption, nanofiltration separation, etc. The method combines nanofiltration with air blowing, integrates the advantages of both, and omits the processes of secondary chlorine oxidation, rectification, bromine reduction and impurity removal, thereby shortening the process flow. However, the method cannot get rid of the dependence on chlorine gas, and there are safety risks and environmental risks. At the same time, in order to ensure the oxidation rate, the method uses a chlorine addition amount of 100-155%. The sodium chloride impurities produced by excessive chlorine gas cannot be separated by nanofiltration process, and finally affect the quality of sodium bromide product.

[0005] CN116161622A discloses a method for preparing bromine by using carnallite mother liquor, which comprises the steps of acidification and oxidation, air blowing, sodium bromide absorption, distillation separation and the like. The method uses hydrogen peroxide as an oxidizing agent instead of chlorine, and the obtained industrial bromine product has a quality superior to that of the superior product specified in the industry standard QB / T2021-1994, and does not contain chlorine ions, and the bromine content can reach more than 99.85%.

[0006] Ozone is a high-efficiency green oxidizing agent, which has been widely used in wastewater regeneration treatment, food preservation, medical disinfection and injection, semiconductor processing and other fields in recent years. The present application uses ozone as an oxidizing agent instead of chlorine to oxidize bromine-containing brine. The principle is that the E0 of ozone in an acidic solution is 2.07V, which is only inferior to fluorine E0=2.87V, and the E0 in an alkaline solution is 1.24V, which is slightly lower than chlorine E0=1.36V, and the E0 in the whole pH range is higher than bromine E0=1.08V, so it has the basis to oxidize bromide ions. According to research reports, the ozone and bromide ion system has the following reactions:

[0007] 2Br - +2O3→2Br·+3O2(1)

[0008] Br·+Br·→Br2(2)

[0009] Br2+3O3+H2O→2HBrO+4O2(3)

[0010] Br2+2HO - →BrO - +Br - +H2O(4)

[0011] BrO - +2O3→BrO3 - +2O2(5)

[0012] Br2+Br - →Br3 - (6)

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

[0014] Therefore, how to strengthen the gas-liquid two-phase flow mass transfer to improve the reaction rate, while controlling the reaction conditions to avoid the production of other bromides except bromine element, and develop a green, safe and efficient chlorine-free process for preparing high-quality sodium bromide is a technical problem that technicians in the field need to solve. SUMMARY

[0015] To solve the above technical problems, the application provides a process for preparing high-quality sodium bromide from bromine-containing brine without chlorine.

[0016] To achieve the above object, the application provides the following technical solutions.

[0017] A process for preparing high-quality sodium bromide from bromine-containing brine without chlorine, which uses ozone as an oxidizing agent to oxidize the bromine-containing brine, and simultaneously uses a gaseous membrane method to prepare sodium bromide.

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

[0019] (1) passing the bromine-containing brine through an acidification treatment and then into ozone for catalytic oxidation, so that the bromide ions in the bromine-containing brine are rapidly oxidized into bromine under the action of a catalyst to obtain an acidified oxidation liquid and bromine-containing air;

[0020] (2) passing the acidified oxidation liquid into the tube side of a three-stage series-connected gaseous membrane system, and simultaneously passing an absorption liquid into the shell side of the three-stage series-connected gaseous membrane system in the reverse direction, so that the bromine diffuses from the acidified oxidation liquid into the absorption liquid through the membrane holes to realize separation and absorption of the bromine, and a first absorption completion liquid and a bromine extraction mother liquor are obtained;

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

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

[0023] Beneficial effects: With the continuous decline of underground brine bromine resource reserves and grade in China, actively developing and utilizing bromine resources in seawater is an inevitable choice to ensure the stable supply of bromine in China. Desalinated concentrated brine or onshore seawater has the advantages of clean water quality, less fouling, large and stable supply, and is the preferred seawater for bromine extraction.

[0024] More preferably, the acidification treatment adjusts the pH value of the bromine-containing brine to 1-1.8 by using sulfuric acid; if the pH value is too high, there are more side reactions in the oxidation process, such as the spontaneous hydrolysis reaction of bromine in water 3Br2+3H2O→BrO3 - +5Br - +6H + , which easily generates bromate, resulting in a low yield of bromine; hydrogen ions can inhibit this reaction process; if the pH value is too low, the acid liquid is wasted, increasing the operating cost.

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

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

[0027] More preferably, the ozone generator uses a constant high-voltage sharp pulse discharge mode, which concentrates the ionization energy of the ozone, improves the utilization rate of electric energy, and reduces the production energy consumption; the high-power power supply is controlled by a diode to achieve multiple rectification, thereby improving the power factor.

[0028] Preferably, in step (1), a supported manganese-based oxide catalyst M x Mn y O z / Al2O3 is used in the catalytic oxidation process, wherein x, y, and z are real numbers, and M is a combination of one or more of Fe, Cd, Co, Ni, Cu, and Zr.

[0029] Beneficial effects: The above catalyst can convert ozone in an aqueous solution into hydroxyl radicals (·OH) with a higher oxidation potential, and the reaction rate of hydroxyl radicals with most organic substances is nearly 7 orders of magnitude higher than that of ozone with organic substances, greatly improving the oxidation efficiency of bromide ions. Metal oxide catalysts generally follow a free radical mechanism, and the introduction of other metals into manganese-based catalysts takes advantage of the synergistic effect between the oxidation and reduction cycles of different metals to further improve the activity of catalytic ozone decomposition, and the surface hydroxyl groups of the oxide complex O3 to accelerate its decomposition to produce ·OH. The addition of the catalyst greatly shortens the residence time of the system in the catalytic oxidation tank, reducing equipment footprint and investment. 6 ~10 10 M -1 ·s -1

[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 added results in a low reaction rate; too much catalyst added increases production operating costs; catalysts with a suitable particle size are carried upward by the flow of the acidified raw material liquid and exist in a flowing state in the bed, improving the reaction contact efficiency; a filter screen is provided above and below the bed to prevent the catalyst from being lost with the acidified raw material liquid; too small a particle size requires too dense a filter screen, which greatly hinders the flow of the acidified raw material liquid; and too large a particle size prevents the catalyst particles from assuming a flowing state in the bed. ​

[0032] Preferably, the catalytic oxidation process adopts a baffle catalytic oxidation device, which comprises a raw material liquid first-stage oxidation chamber, a raw material liquid second-stage oxidation chamber, a raw material liquid third-stage oxidation chamber and a gas-liquid separation chamber connected in series.

[0033] The raw material liquid first-stage oxidation chamber, the raw material liquid second-stage oxidation chamber and the raw material liquid third-stage oxidation chamber each comprise a catalytic bed, and ozone is introduced into the catalytic bed through an ozone first-stage adding pipe, an ozone second-stage adding pipe and an ozone third-stage adding pipe respectively.

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

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

[0036] Preferably, in step (1), the bromine-containing air is used to absorb bromine element in the absorption tower to obtain a second absorption completed liquid and tail gas containing trace bromine.

[0037] The second absorption completed liquid is combined with the first absorption completed liquid for treatment.

[0038] The tail gas containing trace bromine is absorbed by lye in the tail gas purification tower, and then enters an ozone tail gas destroyer to remove ozone, so that the gas can be discharged in accordance with the standard.

[0039] Beneficial effects: The air carrying a part of bromine element out of the catalytic oxidation tank through the ozone introduced into the catalytic oxidation tank, and the devices such as the tail gas absorption tower, the tail gas purification tower and the ozone tail gas destroyer can recover the bromine element carried in the air and destroy the unreacted ozone, thereby preventing environmental pollution and realizing 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 effects: The mixed solution of caustic soda and urea in the present application can react with bromine element as follows: 3Br2+6NaOH+(NH2)2CO→6NaBr+5H2O+N2+CO2, so that the high-quality sodium bromide absorption liquid can be directly obtained, and the high-quality sodium bromide product can be easily obtained. If the concentration of the absorption liquid is too low, the content of sodium bromide in the absorption completed liquid is low, and the amount of water to be evaporated in the subsequent crystallization is large; if the concentration of the absorption liquid is too high, the crystallization may be precipitated to block the pore channel of the gaseous membrane.

[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, and the sodium bromide content is 100-300 g / L.

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

[0044] Preferably, the gaseous membrane system in step (2) is built using a polyvinylidene fluoride hollow fiber membrane assembly with superhydrophobicity obtained by soaking modification with a silane coupling agent for 24 hours.

[0045] Beneficial effects: By introducing low-surface-energy chemicals on the membrane surface, the contact area between water droplets and the membrane surface is reduced, thereby forming a superhydrophobic effect. This treatment not only improves the hydrophobicity of the membrane, but also enhances its oxidation resistance, acid and alkali resistance, and aging resistance, making the membrane material have better stability and durability in harsh environments.

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

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

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

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

[0050] Under the above flow rates, the processing efficiency of the gaseous membrane system can be ensured.

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

[0052] Beneficial effects: The present application fully utilizes the sodium carbonate byproduct in the system to recover the bromine extraction mother liquor, achieving resource recycling.

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

[0054] The application is a green, safe and efficient high-quality sodium bromide preparation technology, which does not need to use chlorine as an oxidant, and does not need to prepare industrial bromine and then react to obtain sodium bromide product, so that the use and generation of dangerous chemicals such as chlorine and bromine are avoided in the whole generation process, and 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, and the main content of sodium bromide is greater than 99%, which is better than the various indicators specified in the industry standard HG / T3809-2006. The process flow is simple, does not need steam, and the production cost is low. In addition, the application combines the advantages of ozone oxidation, air blowing method and gaseous membrane method, improves the safety of production, and realizes efficient utilization of bromine resources in raw materials, and the comprehensive utilization rate of bromide ions can reach more than 95%. BRIEF DESCRIPTION OF DRAWINGS

[0055] The drawings constituting a part of this application serve to provide a further understanding of the application, and the illustrative embodiments of the application and their descriptions serve to explain the application, and do not constitute improper limitations on the application. In the drawings:

[0056] Figure 1 The process flow chart for preparing high-quality sodium bromide from bromine-containing brine without chlorine in the application;

[0057] Figure 2 The schematic diagram of the ozone catalytic oxidation tank device in the application;

[0058] In which the number is: 1, the first ozone adding pipe, 2, the second ozone adding pipe, 3, the third ozone adding pipe, 4, the catalyst bed, 5, the aeration assembly, 6, the first raw material liquid oxidation chamber, 7, the second raw material liquid oxidation chamber, 8, the third raw material liquid oxidation chamber, 9, the gas-liquid separation chamber, 10, the wire mesh demister. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0060] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the drawings and specific embodiments.

[0061] Unless otherwise specified, the raw materials in the embodiments of the application are obtained by commercial purchase;

[0062] Among them, the concentrated brine is taken from the membrane method (RO) seawater desalination by-product containing 6% salt content;

[0063] The supported iron-manganese composite oxide catalyst used in the embodiment of the present application is a supported iron-manganese composite oxide prepared by using ferrous chloride, manganese chloride, sodium hydroxide, gamma-alumina and the like materials by a hydrothermal method, and the composition thereof can be expressed as Fe 0.2 Mn 0.8 O2 / Al2O3.

[0064] The catalytic oxidation process in the embodiment of the present application adopts a baffle plate type catalytic oxidation equipment, as shown in Figure 2 which comprises a raw material liquid first-stage oxidation chamber 6, a raw material liquid second-stage oxidation chamber 7, a raw material liquid third-stage oxidation chamber 8 and a gas-liquid separation chamber 9 connected in series.

[0065] Among them, the raw material liquid first-stage oxidation chamber 6, the raw material liquid second-stage oxidation chamber 7 and the raw material liquid third-stage oxidation chamber 8 respectively comprise a catalytic bed 4, and ozone is introduced into the catalytic bed through ozone first-stage adding pipe 1, ozone second-stage adding pipe 2 and ozone third-stage adding pipe 3 below the catalytic bed, and is contacted with the catalytic bed after aeration by an aeration assembly.

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

[0067] The equipment increases the gas-water cross-section flow velocity, so that the contact between bromine-containing brine and ozone is more frequent, and the gas-liquid mass transfer is strengthened. The residence time of the raw material liquid in the baffle plate type catalytic oxidation tank is controlled to be 60-100s; the residence time is too short, so that the bromine yield is low; and the residence time is too long, so that the required oxidation tank volume is too large, which increases the investment cost.

[0068] The tail gas absorption tower in the embodiment of the present application adopts a glass steel material packing tower, and the empty tower gas velocity is controlled to be 0.8-1.2m / s, so as to ensure the absorption efficiency, and the tower is filled with PP material or PTFE material stepped ring, flower ball and the like scattered packing.

[0069] Embodiment 1

[0070] A process method for preparing high-quality sodium bromide from bromine-containing brine without chlorine, as shown in Figure 1 which comprises the following steps:

[0071] (1) The desalinated concentrated brine (bromine-containing brine) is used as raw material, the bromide ion content of which is about 82mg / L, sulfuric acid is added for acidification treatment, the pH is adjusted to 1.0, the air compressor is started, the air is blown into the ozone generator, the power pulse density is adjusted, and the ozone generator is controlled to pass ozone at 115% of the reaction theoretical calculation amount;

[0072] (2) As shown in Figure 2As shown, the catalytic oxidation tank is divided into three sections (first-stage oxidation chamber 6, second-stage oxidation chamber 7, and third-stage oxidation chamber 8) with a total catalyst bed 4 loading of 12 g / m 3 The liquid feed flow rate is controlled to keep the residence time in the catalytic oxidation tank at about 60 s; at this time, the main reactions occurring in the oxidation tank are 2Br - + 2O3→ 2Br· + 3O2 and Br· + Br·→ Br2; a small amount of BrO3 - undergoes disproportionation in the strong acid system to react with Br - to form 5Br - + BrO3 - + 6H + → 3Br2 + 3H2O. Sampling detects that the bromide ion content of the liquid outlet of the gas-liquid separation chamber 9 of the catalytic oxidation tank is 2.1 mg / L, and the oxidation rate is calculated to be 97.4%, obtaining the acidified oxidation liquid.

[0073] (3) The 8-inch polyvinylidene fluoride hollow fiber membrane is soaked and modified for 24 h using a silane coupling agent to make it super-hydrophobic, and then a three-stage series gaseous membrane system is built using the polyvinylidene fluoride hollow fiber membrane assembly after soaking and modification; the acidified oxidation liquid discharged from the catalytic oxidation tank in step (2) is passed into the tube side of the first-stage gaseous membrane system at a flow rate of 1.0 m 3 / h, the bromine extraction mother liquor obtained from the first-stage gaseous membrane system is passed into the tube side of the second-stage gaseous membrane system, the bromine extraction mother liquor obtained from the second-stage gaseous membrane system is passed into the tube side of the third-stage gaseous membrane system, and the bromine extraction mother liquor obtained from the third-stage gaseous membrane system is passed into the neutralization treatment system; a circulating absorption liquid with a sodium hydroxide mass concentration of 16% and a urea mass concentration of 4.6% is prepared, and the absorption liquid is passed into the shell side of the third-stage gaseous membrane system at a flow rate of 2.5 m 3 / h, the absorption liquid obtained from the third-stage gaseous membrane system is passed into the shell side of the second-stage gaseous membrane system, the absorption liquid obtained from the second-stage gaseous membrane system is passed into the shell side of the first-stage gaseous membrane system, the absorption liquid obtained from the first-stage gaseous membrane system is passed into the absorption liquid circulating tank, and then the absorption liquid is pressurized by a pump and passed into the shell side of the third-stage gaseous membrane system again, and the above steps are repeated until the absorption liquid is enriched to a pH of about 10, and the sodium bromide content is detected to be 262 g / L, obtaining the absorption completed liquid; sampling detects the bromide ion concentration at the outlet of the tube side of each stage of the gaseous membrane system, wherein the bromide ion concentration of the first-stage bromine extraction mother liquor is 29.6 mg / L, the bromide ion concentration of the second-stage bromine extraction mother liquor is 10.2 mg / L, the bromide ion concentration of the third-stage bromine extraction mother liquor is 4.1 mg / 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 three-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 is restored to 6.9; the sodium bromide obtained by cooling and crystallization is washed and dried to obtain a product, which is analyzed and detected, and the quality of the obtained industrial sodium bromide product is superior to each index specified in the industry standard HG / T 3809-2006, and the product does not contain chloride ions, and the main content of sodium bromide is greater than 99%.

[0075] (5) Tail gas treatment: the air containing bromine is discharged from the gas-liquid separation chamber 9 in step (2) at the same time as obtaining the acidified oxidation liquid, that is, a large amount of air introduced by the air compressor carries a small amount of ozone and free bromine, and the air containing bromine enters the tail gas absorption tower; a circulating absorption liquid with a mass concentration of 16% of sodium hydroxide and a mass concentration of 4.6% of urea is prepared, and the air containing bromine is subjected to circulating spraying in the tail gas absorption tower to absorb the bromine therein, at this time, the main reaction occurring in the absorption tower is 3Br2+6NaOH+(NH2)2CO→6NaBr+CO2+N2+5H2O, and the absorption liquid is continuously circulated and enriched to a pH of about 10, and the sodium bromide content is detected to be 259 g / L, which is sent to the crystallization separation system; at the same time, the tail gas after absorption still contains a small amount of bromine, which is further introduced into the purification tower and absorbed by fresh lye, and tail gas containing a small amount of ozone is obtained, which is further introduced into an ozone tail gas destroyer to remove ozone, and finally discharged at a 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) Using natural seawater (bromine-containing brine) as raw material, the bromide ion content is about 53 mg / L, sulfuric acid is added for acidification treatment, and the pH is adjusted to 1.5; start the air compressor, introduce air into the ozone generator, adjust the pulse density of the power supply, and control the ozone generator to pass ozone at 105% of the theoretical calculation amount according to the reaction;

[0079] (2) In the catalytic oxidation tank, three blocks are filled with a total weight of 0.6 g / m 3 of supported iron-manganese composite oxide catalyst, and the liquid feed flow rate is controlled to keep the residence time in the catalytic oxidation tank at about 60 s. The bromide ion content at the outlet of the catalytic oxidation tank is 2.6 mg / L, the oxidation rate is calculated to be 95.1%, and the acidified oxidation liquid is obtained.

[0080] (3) The 8-inch polyvinylidene fluoride hollow fiber membrane is soaked and modified with a silane coupling agent for 24 hours to make it super-hydrophobic, and then a three-stage series gaseous membrane system is built with the soaked and modified polyvinylidene fluoride hollow fiber membrane module; the acidified oxidation liquid discharged from the catalytic oxidation tank in step (2) is fed into the tube side of the first-stage gaseous membrane system at a flow rate of 0.8 m 3 / h, the obtained bromine extraction mother liquor of the first-stage gaseous membrane system is fed into the tube side of the second-stage gaseous membrane system, the obtained bromine extraction mother liquor of the second-stage gaseous membrane system is fed into the tube side of the third-stage gaseous membrane system, and the obtained bromine extraction mother liquor of the third-stage gaseous membrane system is fed into the neutralization treatment system; a circulating absorption liquid with a mass concentration of 8% of sodium hydroxide and a mass concentration of 2.3% of urea is prepared, and the absorption liquid is fed into the shell side of the third-stage gaseous membrane system at a flow rate of 1.5 m 3 / h to absorb the bromide ions in the acidified oxidation liquid in the tube side, wherein the obtained absorption liquid of the third-stage gaseous membrane system is fed into the shell side of the second-stage gaseous membrane system, the obtained absorption liquid of the second-stage gaseous membrane system is fed into the shell side of the first-stage gaseous membrane system, the obtained absorption liquid of the first-stage gaseous membrane system is fed into an absorption liquid circulating tank, and then is pressurized by a pump to be fed into the shell side of the third-stage gaseous membrane system again, and the above steps are repeated until the absorption liquid is enriched to a pH of about 11, the sodium bromide content in the absorption liquid is detected to be 127 g / L, and the absorption completion liquid is obtained; the bromide ion concentration at the outlet of the tube side of each stage of the gaseous membrane system is detected, wherein the bromide ion concentration of the first-stage bromine extraction mother liquor is 16.4 mg / L, the bromide ion concentration of the second-stage bromine extraction mother liquor is 5.7 mg / L, the bromide ion concentration of the third-stage bromine extraction mother liquor is 3.2 mg / L, and the comprehensive utilization rate of bromide ions reaches 94%.

[0081] (4) The obtained absorption completion liquid in step (3) is fed into a crystallization separation system, in which the absorption completion liquid is evaporated by three-effect evaporation to precipitate sodium carbonate, and the sodium carbonate is cooled and crystallized to obtain sodium bromide; the precipitated sodium carbonate is fed into a neutralization treatment system to neutralize and treat the bromine extraction mother liquor, and the bromine extraction mother liquor is discharged after the pH is restored to 6.6; the cooled and crystallized sodium bromide is washed and dried to obtain a product, which is analyzed and detected to have a quality superior to the various indexes specified in the industry standard HG / T 3809-2006, and does not contain chloride ions, and the main content of sodium bromide is ≥99%.

[0082] (5) Tail gas treatment: step (2) discharges bromine-containing air while obtaining acidified oxidation liquid, i.e. a small amount of air containing ozone and free bromine is brought in with the air compressor, and the bromine-containing air enters the tail gas absorption tower; a circulating absorption liquid with a mass concentration of 8% of sodium hydroxide and a mass concentration of 2.3% of urea is prepared, and the bromine-containing air is sprayed in the tail gas absorption tower to absorb the bromine therein, and the absorption liquid is continuously circulated and enriched to a pH of about 11, and the sodium bromide content is detected to be 125 g / L, which is sent to a crystallization separation system; at the same time, a small amount of bromine is also contained in the tail gas after absorption, which is further introduced into the purification tower to be absorbed by fresh lye, and tail gas containing a small amount of ozone is obtained, which is further introduced into an ozone tail gas destroyer to remove ozone, and finally discharged at a 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) Natural seawater mixed with desalinated concentrated seawater is used as raw material (bromine-containing brine), and sulfuric acid is added for acidification treatment to adjust the pH to 1.8; an air compressor is started to bring air into an ozone generator, the pulse density of the power supply is adjusted, and the ozone generator is controlled to pass ozone at 110% of the theoretical calculation amount according to the reaction;

[0086] (2) A total of 1.8 g / m 3 of supported iron-manganese composite oxide catalyst is loaded in three blocks in the catalytic oxidation tank, and the liquid feed flow rate is controlled to keep the residence time in the catalytic oxidation tank at about 70 s. The bromide ion content at the outlet of the catalytic oxidation tank is detected to be 5.4 mg / L, the oxidation rate is calculated to be 92.1%, and the acidified oxidation liquid is obtained.

[0087] (3) A 8-inch polyvinylidene fluoride hollow fiber membrane is soaked in a silane coupling agent for 24 h to make it super-hydrophobic, and then a three-stage series gaseous membrane system is built with the soaked and modified polyvinylidene fluoride hollow fiber membrane assembly; the acidified oxidation liquid discharged from the catalytic oxidation tank in step (2) is passed into the tube side of the first-stage gaseous membrane system at a flow rate of 1.5 m 3 / h, the bromine-removing mother liquor obtained from the first-stage gaseous membrane system is passed into the tube side of the second-stage gaseous membrane system, the bromine-removing mother liquor obtained from the second-stage gaseous membrane system is passed into the tube side of the third-stage gaseous membrane system, and the bromine-removing mother liquor obtained from the third-stage gaseous membrane system is passed into the neutralization treatment system; a circulating absorption liquid with a mass concentration of 10% of sodium hydroxide and a mass concentration of 2.8% of urea is prepared, and the absorption liquid is sprayed at a flow rate of 1.5 m 3The flow of / h is introduced into the shell side of the three-stage gaseous membrane system, the absorption liquid obtained from the three-stage gaseous membrane system is introduced into the shell side of the two-stage gaseous membrane system, the absorption liquid obtained from the two-stage gaseous membrane system is introduced into the shell side of the one-stage gaseous membrane system, the absorption liquid obtained from the one-stage gaseous membrane system is introduced into the absorption liquid circulating tank, and then is pressurized by a pump and introduced into the shell side of the three-stage gaseous membrane system again, and the above steps are repeated until the absorption liquid is continuously enriched to pH = 10 or so, the sodium bromide content in the absorption liquid is detected to be 182 g / L, and the absorption completion liquid is obtained; the bromide ion concentration at the outlet of the tube side of each stage of the gaseous membrane system is detected, wherein the bromide ion concentration of the one-stage bromine extraction mother liquor is 27.2 mg / L, the bromide ion concentration of the two-stage bromine extraction mother liquor is 10.7 mg / L, the bromide ion concentration of the three-stage bromine extraction mother liquor is 6.4 mg / L, and the comprehensive utilization rate of bromide ion reaches 90.5%.

[0088] (4) The absorption completion liquid obtained in step (3) is introduced into a crystallization separation system, in which the absorption completion liquid is subjected to three-effect evaporation to precipitate sodium carbonate, and sodium bromide is obtained after cooling and crystallization; the precipitated sodium carbonate is introduced into a neutralization treatment system to perform neutralization treatment on the bromine extraction mother liquor, and the bromine extraction mother liquor is discharged after the pH value is restored to 7.0; the sodium bromide obtained by cooling and crystallization is washed and dried to obtain a product, and the obtained industrial sodium bromide product is superior to the various indexes specified in the industry standard HG / T 3809-2006, and the product does not contain chloride ions, and the main content of sodium bromide is ≥99% or more.

[0089] (5) Tail gas treatment: the air containing bromine is discharged from step (2) while obtaining the acidified oxidation liquid, that is, a large amount of air introduced by the air compressor carries a small amount of ozone and free bromine, and the air containing bromine is introduced into a tail gas absorption tower; a circulating absorption liquid with a mass concentration of 10% of sodium hydroxide and a mass concentration of 2.8% of urea is prepared, and is sprayed in the tail gas absorption tower to absorb the bromine in the air containing bromine, so that the absorption liquid is continuously enriched to pH = 10 or so, and the sodium bromide content in the absorption liquid is detected to be 177 g / L, and is introduced into the crystallization separation system; at the same time, the tail gas after absorption still contains a small amount of bromine, and the tail gas further enters a purification tower to be absorbed by fresh lye, and tail gas containing a small amount of ozone is obtained, which is further introduced into an ozone tail gas destroyer to remove ozone, and is finally discharged at a high altitude.

[0090] Comparative Example 1

[0091] A process method 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: at this time, the total weight is 12 g / m 3The supported iron-manganese composite oxide catalysts of the application are placed in a one-stage oxidation chamber bed, and 115% of the theoretically calculated amount of ozone is also introduced into the one-stage oxidation chamber at one time; the residence time is kept at 60 s, and then the bromide ion content of the liquid at the liquid outlet of the catalytic oxidation tank gas-liquid separation chamber 9 is detected, which is 18.4 mg / L, and the calculated oxidation rate is 77.56%. Only the bromine oxidized into an element can pass through the gaseous membrane holes into the absorption liquid, and such a low oxidation rate will affect the utilization rate of bromine resources.

[0093] Comparative Example 2

[0094] A process method for preparing high-quality sodium bromide from bromine-containing brine without chlorine, which is different from Example 1 in that a gaseous membrane system including only one stage is used instead of a three-stage series gaseous membrane system in step (3).

[0095] Technical effect: at this time, the acidified oxidation liquid with an oxidation rate of 97.4% is introduced into the tube side of the one-stage gaseous membrane system at a flow rate of 1.0 m 3 / h, a circulating absorption liquid with a mass concentration of 16% of sodium hydroxide and a mass concentration of 4.6% of urea is prepared, the absorption liquid is introduced into the shell side of the one-stage gaseous membrane system at a flow rate of 2.5 m 3 / h, and then the absorption liquid is continuously enriched to pH = 10 or so by pumping, and the sodium bromide content in the absorption complete liquid is detected to be 260 g / L; the bromide ion concentration of the one-stage bromine extraction mother liquor is detected to be 28.7 mg / L, and the comprehensive utilization rate of bromide ions is only 65%. The utilization rate of bromine resources is affected.

[0096] Comparative Example 3

[0097] A process method for preparing high-quality sodium bromide from bromine-containing brine without chlorine, 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: at this time, the reaction is 3Br2+6NaOH→5NaBr+NaBrO3+3H2O, the bromine element is converted into a mixture of sodium bromide and sodium bromate in the absorption liquid, and the two are difficult to completely separate by adjusting the crystallization, so the mass fraction of sodium bromate contained in the obtained industrial sodium bromide product is as high as 0.8%, which is much higher than the industry standard HG / T 3809-2006 which stipulates that the content of bromate (calculated as bromate) in premium product is not more than 0.003%, and the content of bromate (calculated as bromate) in first-class product is not more than 0.005%.

[0099] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A process for the production of high quality sodium bromide from bromine containing brine without chlorine, characterized in that, Sodium bromide is prepared by using ozone as an oxidant to oxidize bromine-containing brine and coupling a gaseous membrane method for bromine extraction process; Specifically comprising the following steps: (1) passing the bromine-containing brine through acidification treatment and then into ozone for catalytic oxidation to obtain an acidified oxidation liquid and bromine-containing air; The total amount of ozone is 105-115% of the theoretical calculation amount of reaction, and the ozone is introduced in three stages, the first stage is 40-50% of the total amount, and the remaining two stages are introduced in equal amounts; In the process of catalytic oxidation, a supported manganese-based oxide catalyst M x Mn y O z / Al2O3, wherein x, y, z are real numbers, and M is a combination of one or more of Fe, Cd, Co, Ni, Cu and Zr; (2) passing the acidified oxidation liquid into the tube of a three-stage series gaseous membrane system, and passing the absorption liquid into the shell of the three-stage series gaseous membrane system in the opposite direction, so that bromine is separated and absorbed from the acidified oxidation liquid to the absorption liquid through the membrane holes to obtain a first absorption completion liquid and a bromine extraction mother liquor; 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%; (3) crystallizing, washing and drying the first absorption completion liquid to obtain sodium bromide product.

2. A process for the production of high quality sodium bromide from bromine containing brine without chlorine as claimed in claim 1, wherein, The bromine-containing brine in step (1) includes desalination concentrated brine or onshore seawater, and the bromide ion concentration is 50-100 mg / L.

3. A process for the production of high quality sodium bromide from bromine containing brine without chlorine as claimed in claim 1, wherein, The bromine-containing air in step (1) is absorbed by the absorption liquid in the tail gas absorption tower to obtain a second absorption completion liquid and tail gas containing trace bromine; The second absorption completion liquid is combined with the first absorption completion liquid for processing; The tail gas containing trace bromine is absorbed by lye in the tail gas purification tower, then enters the ozone tail gas destroyer to remove ozone, and the gas is discharged up to standard.

4. A process for the production of high quality sodium bromide from bromine containing brine without chlorine as claimed in claim 1 or claim 3, wherein, 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.

5. A process for the production of high quality sodium bromide from bromine containing brine without chlorine as claimed in claim 1, wherein, The flow rate of the acidified oxidizing solution in the pipe in step (2) is 0.5-1.5 m 3 / h; The flow rate of the absorbing liquid in the shell side is 1.0-2.5 m 3 / h.

6. A process for the production of high quality sodium bromide from bromine containing brine without chlorine as claimed in claim 1, wherein, The bromine extraction mother liquor in step (2) is neutralized to pH 6-7 using sodium carbonate produced by crystallization separation in step (3) and then discharged.

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