图片名称
+
  • 177831007137293988800.png

Sodium Hydroxide (Caustic Soda) Production Processes

Raw salt is dissolved to prepare saturated crude brine, into which chemical agents are added sequentially to remove impurities such as calcium, magnesium and sulfate radicals. After secondary refining treatment, high-purity refined brine is obtained.Qualified refined brine is fed into the anode chamber of the ion-exchange membrane electrolyzer, while pure water is supplemented to the cathode chamber for electrolysis under direct current.Under the action of the ion-exchange membrane, sodium ions migrate directionally through the membrane into the cathode chamber and combine with hydroxide ions to form liquid sodium hydroxide.Chlorine gas produced at the anode and hydrogen gas produced at the cathode are respectively cooled, washed, dried and compressed before being sent to subsequent processes.The dilute brine after electrolysis is dechlorinated and returned to the salt dissolving section for recycling.The low-concentration liquid caustic soda produced is concentrated by evaporation to prepare 32% and 50% liquid caustic soda, and can be further processed into solid sodium hydroxide products such as flake alkali and granular alkali.

Category:

Chemical Process Technology

Key words:

Message
Contact us

Product Description

 

 

I. Current Status of Sodium Hydroxide (Caustic Soda) Production Processes

The ion-exchange membrane electrolysis process is the mainstream technology for sodium hydroxide production and has become the exclusive preferred process for caustic soda production at home and abroad.With the advantages of low energy consumption, high product purity, favorable environmental performance and high automation level, the ion-exchange membrane process is fully adopted for all newly-built, renovated and expanded caustic soda plants.The development trends of the industry include large-scale installations, low-energy-consumption zero-gap electrolyzers, system intellectualization, comprehensive utilization of by-product hydrogen, and closed circulation of materials.

 

II. Process Description (Sodium Hydroxide Production by Ion-exchange Membrane Method)

Raw salt is dissolved to prepare saturated crude brine, into which chemical agents are added sequentially to remove impurities such as calcium, magnesium and sulfate radicals. After secondary refining treatment, high-purity refined brine is obtained.Qualified refined brine is fed into the anode chamber of the ion-exchange membrane electrolyzer, while pure water is supplemented to the cathode chamber for electrolysis under direct current.Under the action of the ion-exchange membrane, sodium ions migrate directionally through the membrane into the cathode chamber and combine with hydroxide ions to form liquid sodium hydroxide.Chlorine gas produced at the anode and hydrogen gas produced at the cathode are respectively cooled, washed, dried and compressed before being sent to subsequent processes.The dilute brine after electrolysis is dechlorinated and returned to the salt dissolving section for recycling.The low-concentration liquid caustic soda produced is concentrated by evaporation to prepare 32% and 50% liquid caustic soda, and can be further processed into solid sodium hydroxide products such as flake alkali and granular alkali.

 

III. Process Advantages

1.High product purity: The produced caustic soda features extremely low impurity and salt content, reaching the superior product grade.

2.Outstanding environmental performance: The production process causes no pollution with low discharge of three wastes. The closed circulation of the brine system greatly reduces wastewater discharge.

3.High automation and stable operation: The whole plant realizes centralized DCS control with simple operation, stable working conditions and long continuous operation cycle, effectively lowering labor and operation & maintenance costs.

 

Message

Submit