Sodium carbonate manufacturing by synthetic processes in chlor-alkali industry

Soda ash/sodium carbonate manufacturing procedure categorized into two paths as synthetic and natural process. Scientific research has improved the synthetic process by modifying the chemical steps in the process plants by altering the raw material to decrease the manufacturing cost.

Technology:

when sodium carbonate manufacturing process was invented in the year 1773 salt cake is used as raw material. After that, to increase the production capacity and improve the quality chemists introduced new production technologies. One of the chemist was Ernest Solvay, in 1860’s he developed the technique of reacting carbon dioxide to brine and ammonia solution. Process plants were constructed based on his technology up to 1980’s. To decrease the investment cost his process was modified to dual process which produce ammonia chloride as co- product used as fertilizer.

Technologies available to produce soda ash:

  • LeBlanc process  (Non-electrolysis process from brine)
  • Solvay process
  • Dual process(modified solvay process)
  • Ammonia chloride
  • New Asahi
  • Hbls
  • Akzo (Dry lime) process

Brief process description about sodium carbonate manufacturing by various processes:

LeBlanc process:

It is the oldest method of producing soda ash from brine. It is no longer used in production industries. Brine is reacted with H2SO4 to form Na2SO4. Calcium carbonate is added to sodium sulphate and roasted to initiate double decomposition reaction to produce Na2CO3 and CaSO4.

2NaCl + H2SO4 → Na2SO4 +2HCL

Na2SO4 + CaCO3 → Na2CO3 + CaSO4

Engineering problems: Inefficient scrubbing mechanism to prevent HCl fumes loss was one of the major problems in its design and soda ash recovery is not efficient in leaching operation. Most of the heat energy is lost without recovery causing the process to be expensive.

Solvay process:

Raw material used: NaCl, CaCO3 (limestone), ammonia and coke

Steps involved in solvay process are:

  • Lime preparation
  • Brine preparation
  • Ammonia absorption
  • Carbonation
  • Precipitation of bicarbonate
  • Filtration of bicarbonate
  • Ammonia chloride
  • Recovery of ammonia
  • Calcining the bicarbonate to soda ash

Ammonia is used as recycle and tie compound. It reacts with sodium chloride to form ammoniated brine solution that reacts with carbon dioxide to form sodium bicarbonate and ammonium chloride. NaHCO3 is calcined to remove CO2 and water leaving out soda ash. NH4Cl is reacted with calcium oxide to produce ammonia for recycle. NH3 is added to make up the loss in recycling. Carbon dioxide from lime kiln and calciner is used in carbonating tower

Solvay process flow diagram:

Production of soda ash by Solvay process

Solvay process to convert brine to sodium carbonate

Top Sodium Carbonate Manufactures:
ContinentsManufacturesCapacity, MT/annum
North and South AmericaGeneral chemical2540
FMC corporation (natural)3240
Solvay chemicals2540
OCI chemical Corporation2970
Searles Vally Minerals1320
Industrial del Acali570
EuropeZaklad Produckcyjny soda Matwy600
Novacarb600
Solvay Werk Rheinberg645
Solvay-Carbonate France, S.A.S700
Solvay Quimica Sl950
Brunner Mond1000
Beypazari Trona Factory1000
Soda Sanayli1000
Solvay Chimica Italia1020
Solvay Sodi Ad1350
AsiaAchinsk Alumina Refinery595
Berezniki Soda Plant630
Hubei Shuanghuan Science And Technology Co, Ltd640
Bhavanagar Chemical Complex650
Qingdao Soda Ash Industrial Co, Ltd700
Inner Mongolia Yuanxing Natural Akali Co, Ltd700
Gujarat Heavy Chemicals Ltd850
Tianjin Soda Plant880
Tata Chemicals917
Dahua Group Dalian Chemicals Ind920
China Estern United Nanjing Chemical Industries Group Co., Ltd1200
Qinghai Alkali Industry Co, Ltd1800
Tangshan Sanyou Group Alkali Industry Co, Ltd2000
AfricaMagadi Soda Company715
Associations of soda ash manufactures:
  • American chemistry council- US soda ash manufacturer’s panel
  • ESAPA: European Soda Ash Producers Association
  • JSIA: Japan Soda Industry Association
  • CSIA: China Soda Industry Association
  • AMAI: Alkali Manufacturers Association of India