1、 Neutralization method (laboratory/high-purity reagent selection)
      Using hydrobromic acid HBr to undergo acid-base neutralization with sodium base, the product has fewer impurities and is suitable for pharmaceuticals and analytical pure sodium bromide
technological process:
      Stir at room temperature, slowly mix 40% HBr with caustic soda solution, and control the endpoint pH to 7.5-8 (weak alkalinity prevents HBr volatilization);
Activated carbon decolorization and filtration for impurity removal;
    Evaporative concentration, cooling crystallization, centrifugation, and drying at 110 ℃ to obtain anhydrous NaBr.
      Advantages: Single reaction, no side salts, high purity;
      Disadvantages: Hydrobromic acid has a high cost and is not suitable for large-scale industrial production.
2. Hydrobromic acid+sodium carbonate/sodium bicarbonate
      Features: The reaction releases CO ₂, which can intuitively determine the neutralization endpoint; The sodium bicarbonate system has a lot of foam, which needs to be slowly fed into the anti overflow kettle. It is mostly used for laboratory little batch preparation of reagent grade products.
2、 Bromine reduction method (mainstream industrial large-scale process)
      Using liquid bromine Br ₂, soda ash/caustic soda, and reducing agents as raw materials, which are readily available and cost-effective, is the core route for mass production in the factory.
technological process:
      Dissolve soda ash and urea in hot water, stir and cool down;
      Slowly drip liquid bromine (strongly exothermic, temperature controlled to prevent bromine volatilization); Urea acts as a reducing agent to prevent bromine disproportionation from generating impurities such as sodium bromate;
      Activated carbon adsorption decolorization, filter pressing to remove suspended solids;
      MVR evaporation concentration, cooling crystallization, centrifugal dehydration, drying packaging.
      Advantages: Low cost reducing agent, almost no bromate by-products, stable purity of finished products, suitable for industrial production of tens of thousands of tons;
      Disadvantages: Liquid bromine has strong corrosiveness and high requirements for equipment anti-corrosion.
2. Bromine+caustic soda disproportionation carbon reduction method (traditional old process), first step disproportionation (hot alkaline solution with excess bromine):
      Step 2 Solid Reduction for Bromate Removal: Steaming Dry Solid Mixed Carbon Powder and High Temperature Calcination
      Dissolve in water again, filter, and purify by recrystallization.
     Disadvantages: The two-step high-temperature process has high energy consumption, incomplete reduction of bromate is prone to residual impurities, and has gradually been replaced by urea method, which is only used in little old factories. 3. Iron powder bromine soda ash reduction method (niche route): First, bromine and iron are used to form ferrous bromide, which is then replaced with soda ash
     Filter to remove iron carbonate precipitate, and concentrate the filtrate to crystallize.
Advantages: Mild reaction, no need for high temperature;
     Disadvantages: Difficult to remove iron salt impurities, poor color of finished products, only used for low-end industrial sodium bromide.
3、 Extraction method of brine/salt ore (resource-based low-cost process)
     Utilizing natural bromide ions from underground brine, old brine for salt production, and potassium salt tail brine, large-scale low-cost extraction of sodium bromide is carried out, along with supporting processes for the bromine chemical industry park
     Pre treatment of brine: sedimentation and filtration to remove sediment, calcium and magnesium ions, and adjust the acidic pH to 2-5;
Extraction/blow off enrichment of bromine;
     Soda ash reverse extraction neutralization: Bromine is introduced into the reduction solution of soda ash and urea to generate NaBr solution;
     Membrane separation+fractional crystallization: remove impurities such as sodium chloride and sulfate by nanofiltration, and obtain industrial sodium bromide by cooling and crystallization.
     Advantages: Relying on natural brine resources, low raw material costs, suitable for coastal and salt lake bromine chemical bases;
     Limitations: There are many impurities in the brine, the purification process is long, and high-purity products require secondary refining.
4、 Electrolysis method (clean special process)
     1. Purification of crude NaBr aqueous solution by electrolysis of sodium bromide solution through membrane electrolysis, anode Br ⁻ oxidation, cathode hydrogen evolution, removal of heavy metals and chlorine impurities, used for electronic grade high-purity sodium bromide.
     2. Directly electrolyzing salt water to synthesize sodium chloride, acid electrolyzing brine to generate bromine, and then reducing it in situ to produce NaBr. There is no discharge of chlorine gas, which has strong environmental advantages, high equipment investment, and less application.

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