Process for the production of ammonium bromide

Abstract

The invention relates to the chemical technology related to mineral salts and can be used in the chemical industry. A process for the production of ammonium bromide from a bromine-containing polycomponent aqueous mineral raw material, comprising: two-stage oxidation of bromine ions during acidification of the brine using gaseous chlorine; air desorption of the primary bromine; absorption of the same using a cooled solution of ammonium bromide; and reduction using an ammonia solution. The resulting concentrated solution of ammonium bromide is evaporated until crystals are formed. The ammonium bromide crystals are dried, and the mother liquor is used to produce a solution of ammonium bromide as a commercial product.

Description

Technical Field

[0001] This invention relates to the production technology of inorganic compounds, specifically the production process of ammonium bromide. Ammonium bromide is used as a flame retardant in pharmacology and is also a convenient and inexpensive transport feedstock for the production of liquid bromine. This invention relates to chemical technologies related to mineral salts, which can be used in the chemical industry. Background Technology

[0002] There is a known method for producing metal bromides [1], which involves reacting an oxide, a hydrate of an oxide, and a carbonate of their respective metal with bromine in the presence of a reducing agent and water, wherein only water, or a gas, or a mixture of water and gas, is produced, which is used as a reducing agent during oxidation, such as ammonia, urea, cyanamide, ammonium salts, ammonium carbonate, ammonium halides, formaldehyde, hydrazine, formic acid, formamide, oxalic acid, hydroxylamine, and mixtures thereof. According to this method, bromine and a solution of metal hydroxide or carbonate are added to an aqueous solution of the reducing agent. The reagents may be added simultaneously, in batches, or in portions. The resulting concentrated bromide solution is filtered and evaporated; the finished product is separated in a known manner. This method is inefficient and energy-intensive and does not provide a high-quality finished product.

[0003] There is a known method for producing ammonium bromide by reacting a concentrated solution of ammonia with bromine [2]. To implement this method, the reactor is first cooled, and then a small amount of bromine is added. The ammonia released from the solution and the resulting ammonium bromide fumes are captured with water or a weak solution of ammonium bromide.

[0004] The resulting solution was evaporated, then cooled to remove the precipitated bromide crystals, dried, and packaged.

[0005] One known method for producing alkali metal, calcium, and ammonium bromides[3] involves countercurrent extraction of bromides from a (III) ferric bromide solution using an amine salt solution in an organic solvent, followed by re-extraction with a solution of the corresponding metal in countercurrent mode. In this case, a ferric chloride (III) solution is obtained along with the bromide.

[0006] Document [4] describes a method for producing bromine and its salts, which involves the absorption of halogens from a gas mixture using a liquid absorbent. The invention aims to reduce the loss of reducing agents and alkalis, but does not describe the process for producing the bromine-air mixture or the raw materials used.

[0007] The closest method is the production of bromide salts [5], in which bromine is absorbed in an alkaline solution by excess urea at a concentration of 101%-101.5% of the theoretical solution, and then the solution is heated to 60-65°C with a calculated amount of bromine water. This method is energy-intensive, and because carbonates are formed during the bromine reduction process, it is impossible to obtain a high-quality finished product. Summary of the Invention

[0008] The objective of this invention is to obtain high-quality crystalline ammonium bromide and its aqueous solution. The technological advancements include eliminating the stage of purifying bromine-air mixtures from chlorine while maintaining high purity and high bromine extraction rate in the final product.

[0009] This technological achievement is achieved through a two-stage process of oxidizing bromide ions to orthobromine using gaseous chlorine. This minimizes the chlorine impurity content in the bromine-air mixture without requiring additional purification.

[0010] In the process of bromine absorption from a bromine-air mixture, a cooled, high-concentration ammonium bromide solution is used to increase the bromine absorption rate to 99%. The use of relatively inexpensive ammonia or ammonia water as a bromine reducing agent provides high economic efficiency in industrial production.

[0011] According to the claimed method for producing ammonium bromide from a bromine-containing multi-component aqueous mineral feedstock of calcium magnesium chloride type commercial brine, the brine stream purified from dissolved iron, manganese, and insoluble impurities is preheated to 30-35°C, alkalinity is neutralized, and the pH is acidified to 2.5 using an inorganic acid to prevent hydrolysis of free bromine. Then, bromide ions are oxidized to primary bromine using gaseous chlorine in two stages: in the first stage, in countercurrent mode, bromide ions are oxidized to primary bromine at an initial concentration of 73%-74% in a flowing chlorinator; in countercurrent mode, air desorption of primary bromine is carried out in a desorber; and in countercurrent mode, absorption of primary bromine from the bromine-air mixture is carried out by a multi-directional spiral nozzle in a column mass transfer device; a concentration of 400 g / dm³ is used. 3 A cooled ammonium bromide solution was used as an absorbent; then, in a reactor, the primary bromine absorbed in the form of complexed bromine (NH4[Br2]Br) was reduced to bromide ions; the obtained ammonium bromide solution was purified from bromine impurities using formic acid, and then the purified ammonium bromide solution was evaporated in two stages: in the first stage, water vapor was used to recompress and evaporate the solution in a vacuum evaporator to a concentration of 50% ammonium bromide; in the second stage, evaporation was carried out in an evaporator equipped with a steam jacket and an anchor mixer, and evaporation continued until a slurry containing ammonium bromide crystals was obtained, with an ammonium bromide to water ratio of 3:1. The obtained slurry was cooled to 60-62°C and centrifuged to separate the crystallized ammonium bromide from the mother liquor, and then the separated crystals were dried in a spiral dryer. After desorption in the first stage, a multi-component aqueous mineral feedstock containing bromide was provided for the oxidation of bromide ions to primary bromine using gaseous chlorine, with a residual content of up to 88%-90%, to extract the residual bromine content.

[0012] In a preferred embodiment, the subsequent operations of bromine desorption into air, absorption of the bromine-air mixture, reduction of the absorbed bromine, and purification of the resulting ammonium bromide solution are similar to the first stage of oxidation.

[0013] In another preferred embodiment, the purified ammonium bromide solution mixed with the mother liquor is evaporated to the desired density from the stage of obtaining crystalline ammonium bromide to obtain an ammonium bromide solution as a commercial product.

[0014] A chlorinator is a vertical device. A desorber is a column-type mass transfer device. The reactor is a horizontal vessel divided into several sections by baffles: in the first section, bromine is reduced to bromide ions together with ammonia water with a concentration of 25% ammonia; in the second section of the reactor, the absorbent is degassed, and the released nitrogen gas is discharged into the atmosphere. Attached Figure Description

[0015] Figure 1 This diagram schematically illustrates the sequence of actions in a method for producing ammonium bromide from a bromine-containing multi-component aqueous mineral feedstock. The method involves acidifying the initial brine with 31.5% hydrochloric acid to prevent the hydrolysis of free bromine to pH 2.5. The acidified brine then enters the first stage, where 73%–74% of the bromide ions are oxidized from their initial concentration to primary bromine using gaseous chlorine. The oxidation process is controlled by the redox potential of a platinum electrode. The oxidized water then enters the first stage for desorption of primary bromine through the atmosphere, circulating within the system (bromine desorption rate 95%). A bromine-air mixture (BAM) is directionally absorbed by an ammonium bromide (absorbent) solution. The bromine-saturated absorbent is periodically pumped into the reactor, where the bromine is reduced to ammonium bromide by the addition of a 25% ammonia solution (first stage). The resulting ammonium bromide solution is used to produce crystalline ammonium bromide. The air after bromine extraction contains some residual bromine, which is used for desorption in the second stage. The wastewater from the first stage of desorption enters the second stage of gaseous chlorination, where 88%-90% of the bromide ions are oxidized from their residual content to primary bromine. Next, the water from the second stage of oxidation enters the second stage of primary bromine-air desorption. Similar to the first stage, the bromine-air mixture is absorbed by the same absorbent (ammonium bromide solution). The bromine-saturated absorbent is periodically pumped into the reactor, where the process of reducing bromine to ammonium bromide (second stage) occurs by adding 25% ammonia solution. The resulting ammonium bromide solution is used to produce commercially available ammonium bromide solution.

[0016] The wastewater was sent for neutralization in preparation for further treatment. Detailed Implementation

[0017] Example 1. Density is 1130 kg / m³ 3 The brine volume is 2.43m. 3 Its hydrogen index is 5.7, and its composition is as follows: (Ca2+, Mg2+, Sr2+) = 31.7 kg / m³ 3 Total Fe = 0.002 kg / m³ 3 Mg2+=0.003kg / m 3;(K+, Na+, Li+)=27.42kg / m 3 Cl = 74.37 kg / m 3 HCO3- = 0.03 kg / m³ 3 SO42- = 0.73 kg / m³ 3 Br = 2.40 kg / m 3 The solution was acidified to pH 2.5 with 31.5% hydrochloric acid, followed by a first-stage oxidation with gaseous (anodic) chlorine, resulting in a residual Br- content of 0.64 kg / m³. 3 The corresponding oxidation degree is 73.3%; the original bromine is desorbed by the atmosphere and treated with a concentration of 395.5 kg / m³. 3 Ammonium bromide solution was absorbed onto a packed column; the absorbent filled with original bromine was reduced with 25% ammonia solution; the resulting concentrated ammonium bromide solution was evaporated on a gas burner until ammonium bromide crystals precipitated; the resulting crystals were dried in a drying cabinet; the mother liquor was used to obtain an ammonium bromide solution as the product. 4.84 kg of crystalline ammonium bromide was obtained, with a main substance content of 99.15% in the dried product. In the first stage of oxidation and bromine extraction (Br- = 0.64 kg / m³), 3 Following this, the brine enters the second stage of gaseous (anodic) chlorination, with a residual Br- content of 0.07 kg / m³, equivalent to an oxidation degree of 89.0% in this stage. Absorption of the sodium bromide solution and reduction of the original bromine with ammonia are carried out in a similar manner to the first stage. After precipitating the ammonium bromide crystals from the first stage, the resulting concentrate is mixed with the mother liquor and evaporated to the desired density on a gas burner. This solution is then used as the product. The resulting liquid product has a density of 4.46 dm³. 3 Its density is 1233 kg / m³ 3 The sodium bromide content was 32.7%. The overall bromine recovery rate in the brine was 97.1%.

[0018] Example 2. The composition of the initial brine differs from that of Example 1: 1195 kg / m³ 3 It has a hydrogen index of 5.3 and is composed of the following components: (Ca2+, Mg2+, Sr2+) = 49.55 kg / m³ 3 Total Fe = 0.003 kg / m³ 3 Mg2+=0.005kg / m 3 (K+,Na+,Li+) = 25.98 kg / m³ 3 Cl = 166.8 kg / m 3 HCO3- = 0.024 kg / m³ 3 SO42- = 0.55 kg / m³ 3 Br- = 3.12 kg / m 3 The volume of the brine is 2.8 m³. 3The degree of bromine oxidation in the first stage was 73.4%, equivalent to a residual Br concentration of 0.83 kg / m³. 3 In the second stage, the oxidation degree was 89.16%, equivalent to Br- = 0.09 kg / m³. 3 The following results were obtained: 5.7 kg of crystalline ammonium bromide, with a main substance content of 99.02%; 3.83 dm³. 3 The liquid product has a density of 1230 kg / m³. 3 The sodium bromide content was 32.5%. The overall bromine recovery rate in the brine was 97.12%.

[0019] Example 3. The composition of the initial brine differs from that of Example 1: 1364 kg / m³ 3 The hydrogen index is 5.17, and the composition is as follows: (Ca²⁺, Mg²⁺, Sr²⁺) = 162.25 kg / m³ 3 Total Fe = 0.005 kg / m³ 3 Mg 2*=0.005kg / m 3 ;(K*, Na*, Li*)=27.7kg / m 3 Cl = 166.8 kg / m 3 NCO3 = 0.8 kg / m³ 3 SO42- = 0.003 kg / m³ 3 Br- = 8.25 kg / m 3 The volume of the brine is 2.0 m³. 3 The degree of bromine oxidation in the first stage was 73.0%, equivalent to a residual concentration of Br- = 2.23 kg / m³. 3 In the second stage, the oxidation degree was 88.34%, equivalent to Br- = 0.26 kg / m³. 3 The following results were obtained: 14.0 kg of crystalline ammonium bromide had a main substance content of 99.2%; 9.8 dm 3 The liquid product has a density of 1231 kg / m³. 3 The sodium bromide content was 32.6%. The overall bromine recovery rate in the brine was 96.85%.

[0020] refer to:

[0021] 1.USSR Patent No.8215,Class 12 / JHVan der Meulen.1929.

[0022] 2.Pozin METechnology Pertaining to Mineral Salts.4 thed.Leningrad,“Khimiya”Publisher,1974.Part 1.233pp.

[0023] 3.RF Patent No.21354060,published on 27August 1999.

[0024] 4.USSR Inventor's Certificate No.783229,published on 30November 1980.

[0025] 5.USSR Inventor's Certificate No.138232,published on 01January 1961.

Claims

1. A method for producing ammonium bromide from a bromine-containing multi-component aqueous mineral feedstock of calcium magnesium chloride type commercial brine, comprising: preheating a brine stream purified from dissolved iron, manganese, and insoluble impurities to 30-35°C, neutralizing alkalinity, and acidifying to pH 2.5 using an inorganic acid to prevent hydrolysis of free bromine; then oxidizing bromide ions to primary bromine using gaseous chlorine in two stages: in the first stage, in countercurrent mode, oxidizing bromide ions to primary bromine at an initial concentration of 73%-74% in a flowing chlorinator; in countercurrent mode, desorbing the primary bromine into air in a desorber; and in countercurrent mode, absorbing the primary bromine from the bromine-air mixture using a multi-directional spiral nozzle in a column mass transfer device; using a concentration of 400 g / dm³. 3 A cooled ammonium bromide solution is used as the absorbent; then, the primary bromine absorbed in the form of complexed bromine is reduced to bromide ions in a reactor; the obtained ammonium bromide solution is purified from bromine impurities using formic acid, and then the purified ammonium bromide solution is evaporated in two stages: in the first stage, water vapor is used to recompress and evaporate the ammonium bromide solution to a concentration of 50% in a vacuum evaporator; in the second stage, evaporation is carried out in an evaporator equipped with a steam jacket and an anchor mixer, and evaporation continues until a slurry containing ammonium bromide crystals is obtained, with an ammonium bromide to water ratio of 3:

1. The obtained slurry is cooled to 60-62°C and centrifuged to separate the crystallized ammonium bromide from the mother liquor, and then the separated crystals are dried in a spiral dryer. After desorption in the first stage, a multi-component aqueous mineral feedstock containing bromide is provided for oxidizing bromide ions to primary bromine using gaseous chlorine, wherein gaseous chlorine oxidizes 88%-90% of the residual bromide ion content to primary bromine.

2. The method of claim 1, wherein, The following operations are carried out: air desorption of the raw bromine, absorption of the bromine-air mixture with an ammonium bromide solution, and reduction of the absorbed raw bromine to ammonium bromide in the reactor by adding a 25% ammonia solution.

3. The method of claim 1, wherein, The purified ammonium bromide solution mixed with the mother liquor is evaporated to the desired density from the stage of obtaining crystalline ammonium bromide, obtaining the ammonium bromide solution as a commercial product.

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