SALT RECOVERY FROM COKING PLANT WASTEWATER AND CO₂ CAPTURE FOR SODA ASH PRODUCTION
SALT RECOVERY FROM COKING PLANT WASTEWATER AND CO₂ CAPTURE FOR SODA ASH PRODUCTION
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In order to reduce carbon emissions, enhance carbon neutrality, and further utilize waste to reduce consumption and optimize our product chain, our company has developed a new technological process. This process involves extracting salt from coking plant wastewater and capturing CO2 from flue gas to produce pure soda ash.
SALT RECOVERY FROM COKING PLANT WASTEWATER AND CO₂ CAPTURE FOR SODA ASH PRODUCTION
SALT RECOVERY FROM COKING PLANT WASTEWATER AND CO₂ CAPTURE FOR SODA ASH PRODUCTION
Description of Process
Description of Process
The project adopts the ammonia-soda "concentrated gas" alkali production process, which includes carbonization, calcination, and crystallization. This process is a mature and reliable technology in recent years in China's soda ash production. Utilizing CO₂ and liquid ammonia captured from coking plant flue gas emissions, as well as NaCl recovered from coking plant wastewater treatment, pure soda ash and ammonium chloride products are produced.
Key Technological Features:
● Single Carbonization: CO₂ and liquid ammonia are absorbed in one step, followed by a single salt addition.
● Ammonia Absorption: Liquid ammonia is absorbed twice in the process.
● Single Salt Addition: Salt is added once to the crystallizer and dissolved in the mother liquor.
● External Ammonia Evaporation and Cooling: Liquid ammonia in the external cooler evaporates to provide refrigeration. Ammonium chloride is produced through counter-current crystallization.
● Sodium Bicarbonate Suspension Formation: Salt is dissolved in the mother liquor, and ammonia salt water is prepared in two stages. CO₂ and ammonia salt water react in the carbonization tower to form a sodium bicarbonate suspension and ammonium chloride dissolved in the mother liquor.
● Heavy Alkali Separation: The resulting mixed solution is separated by a vacuum horizontal belt filter to isolate heavy alkali. The heavy alkali is calcined in a self-returning alkali vaporizer to produce finished soda ash (Na₂CO₃).
● Gas Recovery: Furnace gas generated during calcination is processed through cyclone separators, electrostatic precipitators, condensers, and scrubbers to recover alkali powder and ammonia gas.
● Water Vapor Condensation and Recycling: Condensed water vapor is partly used as wash water and the remaining portion is combined with scrubbing solution. This mixture is then sent to a storage tank for various ammonium-containing wastewater (dilute solution) produced during production. The diluted solution is pumped into a distillation column for ammonia recovery, with the waste dilute solution recycled back into the system.
● Ammonium Chloride Production: The filtrate rich in ammonium chloride is processed through ammonia absorption, cold precipitation, and salt crystallization in a counter-current process to produce ammonium chloride slurry. The wet ammonium chloride is separated using a filter press and cooled before packaging to produce finished ammonium chloride (NH₄Cl).
Closed-loop System: The mother liquor circulates within the entire system, with no external discharge.
This comprehensive process ensures efficient utilization of resources, minimal waste generation, and environmental sustainability throughout the production cycle.