A bromine extraction method with improved bromide ion oxidation method and its application

Abstract

The invention discloses a bromine extraction method and application of an improved bromide ion oxidation method, belonging to the technical field of bromine extraction. When the invention is used, the oxidation rate of bromide ions is high, all above 95%, and the yield of bromine is also relatively high, no waste is caused during operation, less power is consumed, the operation cost is low, and the obtained bromine products meet the quality standards of industrial bromine. At the same time, the following technical effects are brought about: providing a low-cost and efficient method for industrial production of bromine without chlorine oxidation, which is safe and environmentally friendly to operate, does not generate a large amount of acidic high-salt wastewater, greatly reduces the production cost of the enterprise, and solves the technical problems existing in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of bromine extraction, and in particular relates to a bromine extraction method and application thereof by improving the bromide ion oxidation mode. Background Art

[0002] Bromine is one of the basic chemical raw materials for the production of flame retardants, fire extinguishing agents and photosensitive materials. my country's bromine extraction industry mainly uses Shandong underground brine as raw material, and also uses desalinated concentrated seawater, warm seawater discharged from power plants or chemical plants, or directly uses seawater as raw material to extract bromine.

[0003] At present, bromine extraction is almost always carried out using the process of "chlorine oxidation-air blowing-sulfuric acid dioxide method to capture foam-tail gas closed cycle". Chlorine is a toxic and hazardous chemical. If the equipment is not well sealed during the oxidation process, chlorine will escape into the air and pollute the operating environment. The high concentration of chloride ions in the stripping drainage causes salinization of surface water and soil and corrosion of water conservancy facilities. When the chloride ion concentration is high, calcium and magnesium will dissolve in large quantities. After the wastewater leaks from the tailings pond, it pollutes the groundwater, greatly increasing the concentration of calcium, magnesium and chlorine in the groundwater, seriously affecting the function of water. In severe cases, it cannot be used or used to irrigate farmland. The transportation and use of liquid chlorine are somewhat dangerous. Accidents of human and animal poisoning, and damage to farmland and fish ponds caused by chlorine leakage occur frequently in other industries.

[0004] There is another method of extracting bromine by using the process of "30% hydrogen peroxide oxidation - air blowing - sulfuric acid dioxide method to capture foam - tail gas closed cycle". Although the use of 30% hydrogen peroxide avoids a series of disadvantages of chlorine oxidation, the use of 30% hydrogen peroxide has the problem of excessively high oxidation costs, and the transportation and use of 30% hydrogen peroxide is dangerous to a certain extent. Explosions and fires caused by 30% hydrogen peroxide occur from time to time.

[0005] There is also a process of "10% sodium hypochlorite oxidation - air blowing - sulfuric acid dioxide method to capture foam - tail gas closed cycle" for bromine extraction. Although this method solves the risk of chlorine leakage, compared with chlorine oxidation to extract bromine, the process of 10% sodium hypochlorite oxidation to extract bromine doubles the acid consumption of the chlorine oxidation process. The price of sodium hypochlorite is several times more expensive than chlorine, which leads to an increase in production costs. Summary of the invention

[0006] 1. Problem to be solved

[0007] In view of the shortcomings of the existing technology, a low-cost and efficient method for industrial production of bromine without using chlorine oxidation is provided. The operation is safe and environmentally friendly, and a large amount of acidic high-salt wastewater will not be generated, which greatly reduces the production cost of the enterprise and solves the technical problems existing in the existing technology.

[0008] 2. Technical solution

[0009] To solve the above problems, the present invention adopts the following technical solutions.

[0010] A bromine extraction method for improving the bromide ion oxidation mode comprises the following steps:

[0011] (1) passing water containing bromide ions into an acid adjustment tank, and adjusting the pH of the water to 2-4 with 30% hydrochloric acid, so that the water in the acid adjustment tank becomes an acidified liquid; wherein the bromide ion content is 20 mg / L-10 g / L;

[0012] (2) introducing the acidified liquid into an electrolytic cell, and after power is applied, the bromide ions in the acidified liquid undergo an oxidation reaction at the anode to generate bromine molecules, and the acidified liquid in the electrolytic cell becomes an oxidized liquid; wherein the electrolytic cell is composed of a cathode plate, an anode plate, and a cell body, wherein the anode plate of the electrolytic cell is an electrode plate with a titanium metal surface coated with ruthenium, iridium, or platinum alloy, the cathode is a titanium metal electrode, and the electrolytic cell body is made of PP material;

[0013] (3) The oxidizing liquid in the electrolytic cell is introduced into the stripping tower, and the oxidizing liquid is sprayed down from the top of the stripping tower. The bromine molecules in the oxidizing liquid are blown out by the air flowing from bottom to top in the stripping tower driven by the Roots blower and become air containing bromine molecules. The air containing bromine molecules finally enters the absorption tower from the top of the stripping tower;

[0014] (4) In the absorption tower, bromine molecules flow from top to bottom along with the air pushed by the Roots blower, and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium bromide, and finally obtain a mixed solution of sodium bromide and sodium bromate;

[0015] (5) the mixed solution is pumped into an acid adding tank, and the pH value of the mixed solution is adjusted to 0-1 with 98% concentrated sulfuric acid, so that sodium bromide and sodium bromate react under the action of concentrated sulfuric acid to generate bromine and sodium sulfate, and finally obtain acidified bromine water containing bromine and sodium sulfate;

[0016] (6) introducing the acidified bromine water in the acid adding tank into the distillation tower, spraying the acidified bromine water from the top of the distillation tower, heating the acidified bromine water by water vapor in the distillation tower, and evaporating bromine from the acidified bromine water to become bromine vapor. The evaporated bromine vapor flows from bottom to top in the distillation tower, and finally enters the cooler from the top of the distillation tower. The sodium sulfate solution after distillation flows out from the bottom of the distillation tower and enters the evaporator;

[0017] (7) in an evaporator, evaporating to obtain sodium sulfate solid, and the evaporated sodium sulfate solid enters a dryer to obtain a sodium sulfate solid product;

[0018] (8) In the cooler, bromine vapor is cooled by cooling water and becomes bromine water and bromine. Bromine water and bromine enter the separation bottle from the bottom of the cooler;

[0019] (9) In the separation bottle, bromine and bromine water are separated, and the separated bromine water enters the distillation tower for distillation again, and bromine overflows from the separation bottle into the bromine storage tank to obtain bromine product.

[0020] The above-mentioned method for extracting bromine by improving the bromide ion oxidation method,

[0021] The oxidation rate of bromine molecules in the oxidizing solution is 90-99%, wherein the oxidation rate is the ratio between the actual content of bromine molecules converted from bromide ions in the oxidizing solution and the theoretical yield of bromine molecules converted from bromide ions in the oxidizing solution.

[0022] The above-mentioned method for extracting bromine by improving the bromide ion oxidation method,

[0023] The current density of the solution in step (2) is 300-3000A / m 2 .

[0024] The above-mentioned method for extracting bromine by improving the bromide ion oxidation method,

[0025] When the equipment operates stably, the concentration of sodium bromide in the absorption liquid is 20-30%.

[0026] The above-mentioned method for extracting bromine by improving the bromide ion oxidation method,

[0027] The air volume of the Roots blower and the gas-liquid flow rate ratio of the oxidizing liquid in the stripping tower are 130:1-260:1.

[0028] The above-mentioned method for extracting bromine by improving the bromide ion oxidation method,

[0029] The flow rate ratio of the air containing bromine molecules entering the absorption tower to the flow rate of the sodium hydroxide solution sprayed in the absorption tower by self-circulation is 40:1-100:1.

[0030] The above-mentioned method for extracting bromine by improving the bromide ion oxidation method,

[0031] The mass ratio of the sulfuric acid added in step (5) to the mixed solution of sodium bromide and sodium bromate is 1.5:1-2.7:1.

[0032] The above-mentioned method for extracting bromine by improving the bromide ion oxidation method,

[0033] In step (6), the temperature of the bromine vapor at the top of the distillation tower is 75-90°C.

[0034] The above-mentioned method for extracting bromine by improving the bromide ion oxidation method,

[0035] The cooling temperature of the cooling water in step (8) is 20-30°C.

[0036] Preparation of oxidizing solution

[0037] The acidified solution is pumped into the electrolytic cell. After power is applied, the bromide ions react with the current at the interface between the anode plate and the bromine-containing solution, and the bromide ions are oxidized into bromine element. The chemical reaction equation is:

[0038] 2Br - -2e - =Br2

[0039] Under the action of unidirectional pulse current, hydrogen ions undergo reduction reaction at the interface between the cathode plate and the bromine-containing solution, reducing the hydrogen ions to hydrogen gas. The chemical reaction equation is:

[0040] 2H + +2e - =H2

[0041] About the Blowing Out of Bromine Molecules

[0042] The oxidizing liquid is introduced into the stripping tower, and the bromine is blown out of the water by air according to the gas-liquid equilibrium relationship between the gas and liquid phase concentrations of bromine.

[0043] Preparation of mixed solution of sodium bromide and sodium bromate

[0044] The bromine molecules blown out react with 30% sodium hydroxide solution in the absorption tower. The chemical reaction equation is:

[0045] 6NaOH+3Br2=5NaBr+NaBrO3+3H2O

[0046] Preparation of acidified bromine water

[0047] The mixed solution of sodium bromide and sodium bromate is passed into the acid adding tank, and 98% concentrated sulfuric acid is added to the acid adding tank to make the pH value of the solution 0-1. The chemical reaction equation is:

[0048] 10NaBr+2NaBrO3+6H2SO4=6Br2+6Na2SO4+6H2O

[0049] About the distillation of bromine water

[0050] The boiling point of bromine is 58.78°C, and the boiling point of water is 100°C. Bromine is distilled out in the distillation tower according to the difference in boiling points between bromine and water.

[0051] Separation of bromine and bromine water

[0052] The density of bromine is 3.119 g / mL and the density of water is 1 g / cm 3 In the separation bottle, bromine water and bromine are separated according to the different densities of bromine and water.

[0053] 3. Beneficial effects

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] When the present invention is used, the oxidation rate of bromide ions is high, all above 95%, and the yield of bromine is also relatively high. No waste is caused during the operation, less electric energy is consumed, the operation cost is low, and the obtained bromine products all meet the quality standards of industrial bromine. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The figure is a process flow chart of the bromine extraction method of the present invention.

[0057] Figure 2 is a schematic diagram of an electrolytic cell in the present invention;

[0058] Figure 3 It is a diagram of the acid adjustment and dosing equipment and the electro-oxidation equipment in the present invention;

[0059] Figure 4 This is a diagram of the stripping and absorption equipment in the present invention. DETAILED DESCRIPTION

[0060] The present invention is further described below in conjunction with specific embodiments.

[0061] Example 1

[0062] Figure 1 is a process flow chart of the bromine extraction method of the present invention, Figure 2 Schematic diagram of the electrolytic cell of the present invention.

[0063] Combination Figure 1-Figure 3 For example, water containing bromide ions (300 mg / L) is continuously pumped into the acid adjustment tank by a centrifugal pump, and the pH is adjusted to 4 with 30% hydrochloric acid. The water after pH adjustment is continuously pumped into the electrolytic cell for oxidation by a centrifugal pump, and the oxidized water is transported to the stripping tower through a pipeline. The gas phase outlet at the top of the stripping tower is connected to the top inlet of the absorption tower through a pipeline, and the gas phase outlet at the bottom of the absorption tower is connected to the air inlet at the bottom of the stripping tower through a Roots blower, that is, the Roots blower serves as the power source of the stripping tower and the absorption tower at the same time. The sodium hydroxide solution in the absorption tower is provided with a power source by a centrifugal pump for cyclic spray absorption. The absorption liquid that reaches the absorption focus is pumped into the sulfuric acid acidification tank by a centrifugal pump, and is adjusted to a suitable pH value and then pumped into the distillation tower for distillation. The top of the distillation tower is connected to the heat exchanger through a steel-lined polytetrafluoroethylene pipeline. The bromine vapor is cooled by the heat exchanger and separated in a separation bottle, and the bromine product is obtained after separation in the separation bottle.

[0064] The electrolytic cell is powered with a current density of 300A / m 2Water containing bromide ions passes through the electrolytic cell, and the bromide ions undergo an oxidation reaction in the electrolytic cell to generate bromine elemental substance and become an oxidizing liquid. After the equipment runs stably, the oxidation rate of bromide ions is 99%, which is the ratio between the actual content of bromine molecules converted from bromide ions in the oxidizing liquid and the theoretical yield of bromine molecules converted from bromide ions in the oxidizing liquid.

[0065] Bromine ions (300 mg / L) are oxidized in an electrolytic cell to obtain an oxidizing liquid, which is sprayed down from the top of the stripping tower. Bromine molecules in the oxidizing liquid are blown out from the bottom to the top of the stripping tower to form bromine-containing air, and finally enter the absorption tower from the bottom of the absorption tower. The gas-liquid flow ratio of the air entering the blowing tower to the oxidizing liquid sprayed in the blowing tower is 130:1.

[0066] In the absorption tower, bromine molecules in the bromine-containing air are carried from top to bottom along with the air and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium bromate, and finally a mixed liquid containing sodium bromide and sodium bromate is obtained. The gas-liquid flow ratio of the bromine-containing air flow entering the absorption tower to the self-circulating spray flow of the absorption tower is 40:1.

[0067] When the absorption end point is reached, the solubility of sodium bromide is 20%. In the acid adding tank, the mass ratio of the added sulfuric acid to the mixed liquid of sodium bromide and sodium bromate is 1.5:1.

[0068] The temperature of the top of the distillation tower was 75°C, and the temperature of the cooling water in the cooler was 20°C.

[0069] Example 2

[0070] The water containing bromine ions (1g / L) is continuously pumped into the acid adjustment tank by a centrifugal pump, and the pH is adjusted to 3.5 with 30% hydrochloric acid. The water after the pH adjustment is continuously pumped into the electrolytic cell for oxidation by a centrifugal pump. The oxidized water is transported to the stripping tower through a pipeline. The top gas phase outlet of the stripping tower is connected to the top inlet of the absorption tower through a pipeline. The bottom gas phase outlet of the absorption tower is connected to the air inlet at the bottom of the stripping tower through a Roots blower, that is, the Roots blower serves as the power source of the stripping tower and the absorption tower at the same time. The sodium hydroxide solution in the absorption tower is provided with a power source by a centrifugal pump for circulation spray absorption. The absorption liquid reaching the absorption focus is pumped into the sulfuric acid acid adding tank by a centrifugal pump, and after adjusting to a suitable pH value, it is pumped into the distillation tower for distillation. The top of the distillation tower is connected to the heat exchanger through a steel-lined tetrafluoroethylene pipeline. The bromine vapor is cooled by the heat exchanger and separated in a separation bottle. After separation in the separation bottle, the bromine product is obtained.

[0071] The electrolytic cell is powered on with a current density of 1200A / m2. Water containing bromide ions passes through the electrolytic cell, where the bromide ions undergo an oxidation reaction to generate elemental bromine that becomes an oxidizing liquid. After the equipment runs stably, the oxidation rate of bromide ions is 98%, which is the ratio of the actual content of bromine molecules converted from bromide ions in the oxidizing liquid to the theoretical yield of bromine molecules converted from bromide ions in the oxidizing liquid.

[0072] Bromine ions (1g / L) are oxidized in an electrolytic cell to obtain an oxidizing liquid, which is sprayed down from the top of the stripping tower. Bromine molecules in the oxidizing liquid are blown out from the bottom to the top of the stripping tower to form bromine-containing air, and finally enter the absorption tower from the bottom of the absorption tower. The gas-liquid flow ratio of the air entering the blowing tower to the oxidizing liquid sprayed in the blowing tower is 150:1.

[0073] In the absorption tower, bromine molecules in the bromine-containing air are carried from top to bottom along with the air and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium bromate, and finally a mixed liquid containing sodium bromide and sodium bromate is obtained. The gas-liquid flow ratio of the bromine-containing air flow entering the absorption tower to the self-circulating spray flow of the absorption tower is 60:1.

[0074] When the absorption end point is reached, the solubility of sodium bromide is 22%. In the acid adding tank, the mass ratio of the added sulfuric acid to the mixed liquid of sodium bromide and sodium bromate is 1.5:1.

[0075] The temperature of the top of the distillation tower was 80°C, and the temperature of the cooling water in the cooler was 22°C.

[0076] Example 3

[0077] The water containing bromide ions (2g / L) is continuously pumped into the acid adjustment tank by a centrifugal pump, and the pH is adjusted to 3.3 with 30% hydrochloric acid. The water after the pH adjustment is continuously pumped into the electrolytic cell for oxidation by a centrifugal pump. The oxidized water is transported to the stripping tower through a pipeline. The top gas phase outlet of the stripping tower is connected to the top inlet of the absorption tower through a pipeline. The bottom gas phase outlet of the absorption tower is connected to the air inlet at the bottom of the stripping tower through a Roots blower, that is, the Roots blower serves as the power source of the stripping tower and the absorption tower at the same time. The sodium hydroxide solution in the absorption tower is provided with a power source by a centrifugal pump for circulation spray absorption. The absorption liquid reaching the absorption focus is pumped into the sulfuric acid acid addition tank by a centrifugal pump, and is adjusted to a suitable pH value and then pumped into the distillation tower for distillation. The top of the distillation tower is connected to the heat exchanger through a steel-lined tetrafluoroethylene pipeline. The bromine vapor is cooled by the heat exchanger and separated in a separation bottle. After separation in the separation bottle, the bromine product is obtained.

[0078] The electrolytic cell is powered on with a current density of 1500A / m 2Water containing bromide ions passes through the electrolytic cell, and the bromide ions undergo an oxidation reaction in the electrolytic cell to generate bromine elemental substance and become an oxidizing liquid. After the equipment runs stably, the oxidation rate of bromide ions is 97%, which is the ratio between the actual content of bromine molecules converted from bromide ions in the oxidizing liquid and the theoretical yield of bromine molecules converted from bromide ions in the oxidizing liquid.

[0079] Bromine ions (2g / L) are oxidized in an electrolytic cell to obtain an oxidizing liquid, which is sprayed down from the top of the stripping tower. Bromine molecules in the oxidizing liquid are blown out from the bottom to the top of the stripping tower to form bromine-containing air, and finally enter the absorption tower from the bottom of the absorption tower. The gas-liquid flow ratio of the air entering the blowing tower to the oxidizing liquid sprayed in the blowing tower is 160:1.

[0080] In the absorption tower, bromine molecules in the bromine-containing air are carried from top to bottom along with the air and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium bromate, and finally a mixed liquid containing sodium bromide and sodium bromate is obtained. The gas-liquid flow ratio of the bromine-containing air flow entering the absorption tower to the self-circulating spray flow of the absorption tower is 60:1.

[0081] In the acid adding tank, the mass ratio of sulfuric acid added to the mixed liquid of sodium bromide and sodium bromate is 1.6:1.

[0082] The temperature of the top of the distillation tower was 80°C, and the temperature of the cooling water in the cooler was 23°C.

[0083] Example 4

[0084] The water containing bromine ions (4g / L) is continuously pumped into the acid adjustment tank by a centrifugal pump, and the pH is adjusted to 3.0 with 30% hydrochloric acid. The water after the pH adjustment is continuously pumped into the electrolytic cell for oxidation by a centrifugal pump. The oxidized water is transported to the stripping tower through a pipeline. The top gas phase outlet of the stripping tower is connected to the top inlet of the absorption tower through a pipeline. The bottom gas phase outlet of the absorption tower is connected to the air inlet at the bottom of the stripping tower through a Roots blower, that is, the Roots blower serves as the power source of the stripping tower and the absorption tower at the same time. The sodium hydroxide solution in the absorption tower is provided with a power source by a centrifugal pump for circulation spray absorption. The absorption liquid reaching the absorption focus is pumped into the sulfuric acid acid adding tank by a centrifugal pump, and after adjusting to a suitable pH value, it is pumped into the distillation tower for distillation. The top of the distillation tower is connected to the heat exchanger through a steel-lined tetrafluoroethylene pipeline. The bromine vapor is cooled by the heat exchanger and separated in a separation bottle. After separation in the separation bottle, the bromine product is obtained.

[0085] The electrolytic cell is powered, and the current density is 1600A / m 2Water containing bromide ions passes through the electrolytic cell, and the bromide ions undergo an oxidation reaction in the electrolytic cell to generate bromine elemental substance and become an oxidizing liquid. After the equipment runs stably, the oxidation rate of bromide ions is 96.5%, which is the ratio between the actual content of bromine molecules converted from bromide ions in the oxidizing liquid and the theoretical yield of bromine molecules converted from bromide ions in the oxidizing liquid.

[0086] Bromine ions (4g / L) are oxidized in an electrolytic cell to obtain an oxidizing liquid, which is sprayed down from the top of the stripping tower. Bromine molecules in the oxidizing liquid are blown out from the bottom to the top of the stripping tower to form bromine-containing air, and finally enter the absorption tower from the bottom of the absorption tower. The gas-liquid flow ratio of the air entering the blowing tower to the oxidizing liquid sprayed in the blowing tower is 170:1.

[0087] In the absorption tower, bromine molecules in the bromine-containing air are carried from top to bottom along with the air and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium bromate, and finally a mixed liquid containing sodium bromide and sodium bromate is obtained. The gas-liquid flow ratio of the bromine-containing air flow entering the absorption tower to the self-circulating spray flow of the absorption tower is 65:1.

[0088] In the acid adding tank, the mass ratio of sulfuric acid added to the mixed liquid of sodium bromide and sodium bromate is 1.7:1.

[0089] The temperature of the top of the distillation tower was 82°C, and the temperature of the cooling water in the cooler was 24°C.

[0090] Example 5

[0091] The water containing bromine ions (7g / L) is continuously pumped into the acid adjustment tank by a centrifugal pump, and the pH is adjusted to 3 with 30% hydrochloric acid. The water after the pH adjustment is continuously pumped into the electrolytic cell for oxidation by a centrifugal pump, and the oxidized water is transported to the stripping tower through a pipeline. The top gas phase outlet of the stripping tower is connected to the top inlet of the absorption tower through a pipeline, and the bottom gas phase outlet of the absorption tower is connected to the air inlet at the bottom of the stripping tower through a Roots blower, that is, the Roots blower serves as the power source of the stripping tower and the absorption tower at the same time, and the sodium hydroxide solution in the absorption tower is provided by the centrifugal pump for circulation spray absorption. The absorption liquid reaching the absorption focus is pumped into the sulfuric acid acid adding tank by a centrifugal pump, and after adjusting to a suitable pH value, it is pumped into the distillation tower for distillation. The top of the distillation tower is connected to the heat exchanger through a steel-lined tetrafluoroethylene pipeline. The bromine vapor is cooled by the heat exchanger and separated in a separation bottle, and the bromine product is obtained after separation in the separation bottle.

[0092] The electrolytic cell is powered on, and the current density is 1800A / m 2Water containing bromide ions passes through the electrolytic cell, and the bromide ions undergo an oxidation reaction in the electrolytic cell to generate bromine elements and become an oxidizing liquid. After the equipment runs stably, the oxidation rate of bromide ions is 96%, which is the ratio between the actual content of bromine molecules converted from bromide ions in the oxidizing liquid and the theoretical yield of bromine molecules converted from bromide ions in the oxidizing liquid.

[0093] Bromine ions (7g / L) are oxidized in an electrolytic cell to obtain an oxidizing liquid, which is sprayed down from the top of the stripping tower. Bromine molecules in the oxidizing liquid are blown out from the bottom to the top of the stripping tower to form bromine-containing air, and finally enter the absorption tower from the bottom of the absorption tower. The gas-liquid flow ratio of the air entering the blowing tower to the oxidizing liquid sprayed in the blowing tower is 180:1.

[0094] In the absorption tower, bromine molecules in the bromine-containing air are carried from top to bottom along with the air and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium bromate, and finally a mixed liquid containing sodium bromide and sodium bromate is obtained. The gas-liquid flow ratio of the bromine-containing air flow entering the absorption tower to the self-circulating spray flow of the absorption tower is 70:1.

[0095] In the acid adding tank, the mass ratio of added sulfuric acid to the mixed liquid of sodium bromide and sodium bromate is 1.9:1.

[0096] The temperature of the top of the distillation tower was 85°C, and the temperature of the cooling water in the cooler was 25°C.

[0097] Example 6

[0098] The water containing bromine ions (9g / L) is continuously pumped into the acid adjustment tank by a centrifugal pump, and the pH is adjusted to 2.5 with 30% hydrochloric acid. The water after the pH adjustment is continuously pumped into the electrolytic cell for oxidation by a centrifugal pump, and the oxidized water is transported to the stripping tower through a pipeline. The top gas phase outlet of the stripping tower is connected to the top inlet of the absorption tower through a pipeline, and the bottom gas phase outlet of the absorption tower is connected to the air inlet at the bottom of the stripping tower through a Roots blower, that is, the Roots blower is used as the power source of the stripping tower and the absorption tower at the same time, and the sodium hydroxide solution in the absorption tower is provided with a power source by a centrifugal pump for circulation spray absorption. The absorption liquid reaching the absorption focus is pumped into the sulfuric acid acid addition tank by a centrifugal pump, and is adjusted to a suitable pH value and then pumped into the distillation tower for distillation. The top of the distillation tower is connected to the heat exchanger through a steel-lined tetrafluoroethylene pipeline, and the bromine vapor is cooled by the heat exchanger and separated in a separation bottle, and the bromine product is obtained after separation in the separation bottle.

[0099] The electrolytic cell is powered, and the current density is 2200A / m 2Water containing bromide ions passes through the electrolytic cell, and the bromide ions undergo an oxidation reaction in the electrolytic cell to generate bromine elemental substance and become an oxidizing liquid. After the equipment runs stably, the oxidation rate of bromide ions is 95%, which is the ratio between the actual content of bromine molecules converted from bromide ions in the oxidizing liquid and the theoretical yield of bromine molecules converted from bromide ions in the oxidizing liquid.

[0100] Bromine ions (9g / L) are oxidized in an electrolytic cell to obtain an oxidizing liquid, which is sprayed down from the top of the stripping tower. Bromine molecules in the oxidizing liquid are blown out from the bottom to the top of the stripping tower to form bromine-containing air, and finally enter the absorption tower from the bottom of the absorption tower. The gas-liquid flow ratio of the air entering the blowing tower to the oxidizing liquid sprayed in the blowing tower is 200:1.

[0101] In the absorption tower, bromine molecules in the bromine-containing air are carried from top to bottom along with the air and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium bromate, and finally a mixed liquid containing sodium bromide and sodium bromate is obtained. The gas-liquid flow ratio of the bromine-containing air flow entering the absorption tower to the self-circulating spray flow of the absorption tower is 80:1.

[0102] In the acid adding tank, the mass ratio of sulfuric acid added to the mixed liquid of sodium bromide and sodium bromate is 2:1.

[0103] The temperature of the top of the distillation tower was 85°C, and the temperature of the cooling water in the cooler was 25°C.

[0104] Example 7

[0105] The water containing bromine ions (10g / L) is continuously pumped into the acid adjustment tank by a centrifugal pump, and the pH is adjusted to 2 with 30% hydrochloric acid. The water after the pH adjustment is continuously pumped into the electrolytic cell for oxidation by a centrifugal pump, and the oxidized water is transported to the stripping tower through a pipeline. The top gas phase outlet of the stripping tower is connected to the top inlet of the absorption tower through a pipeline, and the bottom gas phase outlet of the absorption tower is connected to the air inlet at the bottom of the stripping tower through a Roots blower, that is, the Roots blower serves as the power source of the stripping tower and the absorption tower at the same time. The sodium hydroxide solution in the absorption tower is provided with a power source by a centrifugal pump for circulation spray absorption. The absorption liquid reaching the absorption focus is pumped into the sulfuric acid acid adding tank by a centrifugal pump, and is adjusted to a suitable pH value and then pumped into the distillation tower for distillation. The top of the distillation tower is connected to the heat exchanger through a steel-lined tetrafluoroethylene pipeline. The bromine vapor is cooled by the heat exchanger and separated in a separation bottle, and the bromine product is obtained after separation in the separation bottle.

[0106] The electrolytic cell is powered on, with a current density of 2800A / m 2Water containing bromide ions passes through the electrolytic cell, and the bromide ions undergo an oxidation reaction in the electrolytic cell to generate bromine elements and become an oxidizing liquid. After the equipment runs stably, the oxidation rate of bromide ions is 96%, which is the ratio between the actual content of bromine molecules converted from bromide ions in the oxidizing liquid and the theoretical yield of bromine molecules converted from bromide ions in the oxidizing liquid.

[0107] Bromine ions (10 mg / L) are oxidized in an electrolytic cell to obtain an oxidizing liquid, which is sprayed down from the top of the stripping tower. Bromine molecules in the oxidizing liquid are blown out from the bottom to the top of the stripping tower to form bromine-containing air, and finally enter the absorption tower from the bottom of the absorption tower. The gas-liquid flow ratio of the air entering the blowing tower to the oxidizing liquid sprayed in the blowing tower is 210:1.

[0108] In the absorption tower, bromine molecules in the bromine-containing air are carried from top to bottom along with the air and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium bromate, and finally a mixed liquid containing sodium bromide and sodium bromate is obtained. The gas-liquid flow ratio of the bromine-containing air flow entering the absorption tower to the self-circulating spray flow of the absorption tower is 90:1.

[0109] In the acid adding tank, the mass ratio of sulfuric acid added to the mixed liquid of sodium bromide and sodium bromate is 2.6:1.

[0110] The temperature of the top of the distillation tower was 90°C, and the temperature of the cooling water in the cooler was 30°C.

[0111] According to the control parameters of Examples 1-7, after the equipment has been running continuously and stably, the process indicators within 1 hour are respectively intercepted, and the following results are obtained, as shown in Table 1.

[0112] Table 1 Test results

[0113]

[0114] It can be seen from the table that when the present invention is used, the oxidation rate of bromide ions is high, all above 95%, and the yield of bromine is also relatively high, no waste is caused during the operation, less power is consumed, the operation cost is low, and the obtained bromine products meet the quality standards of industrial bromine.

[0115] The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the scope of protection determined by the claims submitted for the present invention.

Claims

1. A method for extracting bromine by improving the oxidation mode of bromide ions, characterized in that: The following steps are involved: (1) Pass water containing bromide ions into the acid adjustment tank, and use 30% hydrochloric acid to adjust the pH of the water to 2-4, so that the water in the acid adjustment tank becomes acidified liquid; the bromide ion content is 20mg / L-10g / L; (2) The acidified liquid is introduced into the electrolytic cell. After power is applied, the bromide ions in the acidified liquid undergo an oxidation reaction at the anode to generate bromine molecules, and the acidified liquid in the electrolytic cell becomes an oxidized liquid. The electrolytic cell is composed of a cathode plate, an anode plate and a cell body, wherein the anode plate of the electrolytic cell is an electrode plate with a titanium metal surface coated with ruthenium, iridium, or platinum alloy, the cathode is a titanium metal electrode, and the electrolytic cell body is made of PP material; The oxidation rate of bromine molecules in the oxidation solution is 90-99%, wherein the oxidation rate is the ratio between the actual content of bromine molecules converted from bromide ions in the oxidation solution and the theoretical yield of bromine molecules converted from bromide ions in the oxidation solution; (3) The oxidizing liquid in the electrolytic cell is introduced into the stripping tower. The oxidizing liquid is sprayed down from the top of the stripping tower. The bromine molecules in the oxidizing liquid are blown out by the air flowing from bottom to top in the stripping tower driven by the Roots blower and become air containing bromine molecules. The air containing bromine molecules finally enters the absorption tower from the top of the stripping tower. Among them, bromine is blown out of water by air according to the gas-liquid equilibrium relationship between the gas and liquid phase concentrations of bromine; (4) In the absorption tower, bromine molecules flow from top to bottom along with the air pushed by the Roots blower, and are absorbed by the 30% sodium hydroxide solution sprayed from the top of the absorption tower to generate sodium bromide and sodium hypobromite, and finally obtain a mixed solution of sodium bromide and sodium bromate; the bromine molecules after being blown out react with the 30% sodium hydroxide solution in the absorption tower, and the chemical reaction equation is: 6NaOH+3Br2=5NaBr+NaBrO3+3H2O; the flow rate ratio of the air containing bromine molecules entering the absorption tower to the flow rate of the sodium hydroxide solution sprayed in the absorption tower by self-circulation is 40:1-100:1; (5) The mixed solution is pumped into an acid adding tank, and the pH value of the mixed solution is adjusted to 0-1 with 98% concentrated sulfuric acid, so that sodium bromide and sodium bromate react under the action of concentrated sulfuric acid to generate bromine and sodium sulfate, and finally acidified bromine water containing bromine and sodium sulfate is obtained; The mixed solution of sodium bromide and sodium bromate is passed into the acid adding tank, and 98% concentrated sulfuric acid is added into the acid adding tank to make the pH value of the solution 0-1; The chemical reaction equation is: 10NaBr+2NaBrO3+6H2SO4=6Br2+6Na2SO4+6H2O; (6) The acidified bromine water in the acid adding tank is introduced into the distillation tower. The acidified bromine water is sprayed down from the top of the distillation tower. The acidified bromine water is heated by water vapor in the distillation tower, and bromine is evaporated from the acidified bromine water to become bromine vapor. The evaporated bromine vapor flows from bottom to top in the distillation tower and finally enters the cooler from the top of the distillation tower. The sodium sulfate solution after distillation flows out from the bottom of the distillation tower and enters the evaporator; (7) In the evaporator, evaporation is performed to obtain sodium sulfate solid, and the evaporated sodium sulfate solid enters the dryer to obtain a sodium sulfate solid product; (8) In the cooler, bromine vapor is cooled by cooling water and becomes bromine water and bromine. Bromine water and bromine enter the separation bottle from the bottom of the cooler; (9) In the separation bottle, bromine and bromine water are separated. The separated bromine water enters the distillation tower for distillation again. Bromine overflows from the separation bottle into the bromine storage tank to obtain bromine product.

2. The bromine extraction method of improving the bromide ion oxidation method according to claim 1, characterized in that: The current density of electrolysis in step (2) is 300-3000A / m 2 .

3. The bromine extraction method of improving the bromide ion oxidation method according to claim 1, characterized in that: When the equipment is running stably, the concentration of sodium bromide in the absorption liquid is 20-30%.

4. The bromine extraction method of improving the bromide ion oxidation method according to claim 1, characterized in that: The air volume of the Roots blower and the gas-liquid flow rate ratio of the oxidizing liquid in the stripping tower are 130:1-260:

1.

5. The bromine extraction method of improving the bromide ion oxidation method according to claim 1, characterized in that: The mass ratio of the sulfuric acid added in step (5) to the mixed solution of sodium bromide and sodium bromate is 1.5:1-2.7:

1.

6. The bromine extraction method of improving bromide ion oxidation method according to claim 1, characterized in that: The temperature of the bromine vapor at the top of the distillation tower in step (6) is 75-90°C.

7. The bromine extraction method of claim 1, wherein: The cooling temperature of the cooling water in step (8) is 20-30°C.

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