Patent Application
20250002361
The invention relates to technology for producing inorganic compounds, namely, to the process of producing sodium bromide, which is in the chemical synthesis of organobromine compounds, as well as in the oil and gas industry as a component of heavy process fluids during well drilling, killing, and servicing. The invention relates to chemical technology pertaining to mineral salts and can be used in the chemical industry.
There is a known method for producing metal bromides [1] by reacting oxides, hydroxides, and carbonates of the respective metals with bromine in the presence of reducing agents and water, in which substances that produce only water, or gases, or water and gases together upon oxidation are used as reducing agents, for example, 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 dosed into an aqueous solution of a reducing agent. Reagents are dosed simultaneously, in portions, or one at a time. The resulting concentrated solution of bromide salt is filtered and evaporated; the finished product is isolated in a known manner. This method [1] is low-productive and energy-intensive and does not provide a high-quality finished product.
There is a method for air desorption of bromine [2]. This method can be used to extract bromine from brines with low bromine content (up to 1 g/dm3).
The process includes the following stages: (1) acidification of the brine; (2) oxidation of bromide ions with chlorine to elementary bromine; (3) distillation of bromine with air; (3) purification of the bromine-air mixture from chlorine; (4) capture of bromine from the bromine-air mixture with chemical absorbers; (5) processing of the resulting intermediates into commercial products; and (6) neutralization of the brine spent.
There is a method for producing bromides of alkali metals, calcium, and ammonium [3] by countercurrent extraction of bromide from a solution of iron (III) bromide with solutions of amine salts in an organic solvent, and re-extraction is performed with solutions of the respective metals in a countercurrent mode. In this case, along with bromides, a solution of iron (III) chloride is obtained.
The document [4] describes a method for producing bromine and its salts, which relates to the technique of absorbing halogens from gas mixtures with liquid absorbers. This invention aims to lower the losses of the reducing agent and alkaline agent, but there is no description of the process for obtaining the bromine-air mixture and the feedstock used.
The patent [5] describes technology for purifying liquid bromine, which includes the absorption of bromine by a 30% sodium bromide solution with the further addition of an alkaline agent to obtain a mixture of sodium bromide as a product.
The closest is the method for producing bromide salts [6], in which bromine is absorbed with an excess amount of urea in an alkaline solution in an amount of 101%-101.5% of the theoretical, followed by heating the solution to 60-65° C. with a calculated amount of bromine water. This method [6] is energy-intensive and does not allow obtaining a high-quality finished product due to the formation of carbonates during the reduction of bromine.
The essence of the invention is to obtain high-quality crystalline sodium bromide and its aqueous solution, eliminating the stage of purifying the bromine-air mixture from chlorine and maintaining high purity of the final products and a high degree of bromine extraction.
The technical result is achieved through a two-stage process of oxidation of bromide ions to elementary bromine with gaseous chlorine, which allows minimizing the content of chlorine impurities in the bromine-air mixture without its additional purification.
In the process of absorbing bromine from the bromine-air mixture, a cooled, highly concentrated solution of sodium bromide is used, which increases the degree of bromine absorption to 99%. The use of relatively cheap ammonia or ammonia water as a bromine reducer provides high economic performance in industrial production.
Example 1. 10.65 m3 of brine with a density of 1,154 kg/m3, with a hydrogen index of 5.84 of the following composition: Σ(Ca2+, Mg2+, Sr2+)=36.51 kg/m3; Fetotal=0.0002 kg/m3; Σ(K+, Na+, Li+)=25.40 kg/m3; Cl−=142.92 kg/m3; HCO3−=0.076 kg/m3; SO42−=0.46 kg/m3; Br−=2.94 kg/m3 was acidified with 30% hydrochloric acid to pH=2.5 and subjected to one stage of oxidation with gaseous (anodic) chlorine to a residual content of Br−=1.05 kg/m3, which corresponds to the degree of oxidation=64.3%; elementary bromine was desorbed by atmospheric air and absorbed by a solution of sodium bromide with a concentration of 57.3 kg/m3 on a packed column; the absorbent saturated with elementary bromine was reduced with ammonia water in the presence of sodium hydroxide; the resulting concentrate of sodium bromide (density=1,373 kg/m3, bromide concentration=508 kg/m3) was evaporated on a gas burner until sodium bromide crystals precipitated; the resulting crystals were dried in a drying cabinet; the mother liquor was used to obtain sodium bromide solution as a product. As a result, 20.5 kg of crystalline sodium bromide with a content of the main substance in the dry product of 99.28% was obtained. After Stage I of oxidation and bromine extraction (Br−=1.05 kg/m3), brine in a volume of 10.65 m3 entered Stage II of oxidation with gaseous (anodic) chlorine to a residual content of Br−=0.30 kg/m3, which corresponds to the degree of oxidation for this stage=71.2%. The absorption of sodium bromide solution and the reduction of elementary bromine with ammonia water was performed similarly to Stage I. The resulting concentrate was mixed with the mother liquor after precipitation of sodium bromide crystals from Stage I and evaporated on a gas burner to the required density, and this solution was used as a product. The resulting liquid product was 15.3 dm3 with a density of 1,495 kg/m3 and sodium bromide content of 44.4%. The overall degree of bromine recovery from the brine was 89%.
Example 2. The composition of the initial brine differs from Example 1: 1,152 kg/m3, with a hydrogen index of 5.8 of the following composition: Σ(Ca2+, Mg2+, Sr2+)=41.17 kg/m3; Fetotal=0.0002 kg/m3; Σ(K+, Na+, Li+)=31.92 kg/m3; Cl−=151.12 kg/m3; HCO3−=0.03 kg/m3; SO42−=0.52 kg/m3; Br−=2.32 kg/m3. The volume of brine was 10.5 m3. The degree of oxidation of bromine in Stage I was 75%, which corresponds to the residual concentration Br−=0.58 kg/m3 in Stage II, the degree of oxidation was 74.1%, which corresponds to Br=0.15 kg/m3. The following was obtained: 19.2 kg of crystalline sodium bromide with main substance content of 98.51%; 16.6 dm3 of liquid product with a density of 1,470 kg/m3 and sodium bromide content of 44.1%. The overall degree of bromine recovery from the brine was 93.5%.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021119670 | Jul 2021 | RU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/RU2021/000367 | 8/26/2021 | WO |
