Monitoring Chlor-Alkali production processes

Monitoring Chlor-Alkali production processes

Process Analyzers can be used in several stages of the production process. For high feed concentrations of calcium/magnesium to very low concentrations in the ultra-purified brine. The method is based on photometric determination using a standardised method. Other applications are available for the Chlor-Alkali industry like: acidity, carbonate, hydroxide, silica, alumina, ammonia, iodate and chlorine.

Chlor-Alkali Production Process Monitoring

The chlor-alkali production process mainly relies upon the electrolysis of NaCl brine to produce caustic soda (sodium hydroxide, NaOH) and chlorine (Cl2), which are then used in countless other industries.

Three main techniques are in use for the production of chlor-alkali from salt: the membrane technology which accounted for 59.2% of production in Europe in 2014, followed by the mercury process (24.7%) and the diaphragm process (13.7%). All new plants are based on the membrane technique, which does not include mercury and asbestos like the other processes. The shift towards membrane technology is in line with Euro Chlor’s voluntary agreement to phase out the installed mercury capacity by 2020.

Brine Purity

In the membrane electrolysis production of chlor-alkali, the purity of the brine is very important. The presence of impurities such as calcium and magnesium can shorten the performance and lifetime of the membranes or can damage the electrodes. Partial membrane blockage from precipitation reactions will lead to high electrical operational costs and the high cost associated with replacing membranes.

Online Applications for Chlor-Alkali Processes

Brine Production:

  • Alkalinity in Brine (Brine Production)
  • Bromide [Br] in Brine (Brine production)
  • Calcium [Ca2+] in Brine (NaCl Production)
  • Chloride [Cl] in Brine (Brine production)

Brine Purification:

  • Caustic [OH] + Carbonate [CO32-] in Brine (Pretreatment Raw Brine)
  • Hydroxide [OH], Carbonate [CO32-], + Calcium [Ca2+] in Brine (Brine Purification)
  • Hydroxide [OH], Carbonate [CO32-], + Hypochlorite [ClO] in Brine
  • Magnesium [Mg2+] in Brine (Brine Purification)
  • Sodium Hydroxide [NaOH] in Brine (Brine Pre-Treatment)
  • Sodium Hydroxide [NaOH], Chlorine [Cl2], +Carbonate [CO32-] in Brine (Brine Purification)

Chlorine Production:

  • Chloride [Cl] in 50% Sodium Hydroxide [NaOH] (Chlorine production)
  • Chlorine [Cl2], Hydroxide [OH], Carbonate [CO32-], Chloride [Cl], + pH in Brine (Chlorine plant)
  • Potassium iodate [KIO3] in Brine (Chlorine production)

Ion Exchange Cell Membrane Electrolyzer:

  • Calcium [Ca2+] + Magnesium [Mg2+] in Brine (Inlet Membrane Electrolyzer, Brine Treatment)
  • Calcium [Ca2+], Magnesium [Mg2+], + Chloride [Cl] in Brine with % Hydrochloric Acid [HCl] (Inlet Membrane Electrolyzer)
  • Calcium [Ca2+], Magnesium [Mg2+], Sodium Hydroxide [NaOH], + Sodium Carbonate [Na2CO3] in Brine (Inlet Resin Treatment)
  • Chlorate [ClO3] in Brine (Inlet Membrane Electrolyzer)
  • Chlorine [Cl2] in Brine (Outlet Membrane Electrolyzer)

Secondary Purification Resin Treatment:

  • Hydroxide [OH] + Carbonate [CO32-] in Brine (Brine Purification, Resin Treatment)

Waste Water:

  • Chloride [Cl] in effluent waste to river (Effluent WWTP to river)
  • Hypochlorite [ClO] + Sulfite [SO3] (Mercury Cell Effluent)
  • Sulfate [SO42-], Chlorine [Cl2], + pH in waste water (Effluent WWTP)

Other Applications for the Chlor-Alkali Industry:

  • Ammonia [NH3], Total Alkalinity, Carbonate [CO32-], + Chloride [Cl] in Brine
  • Carbonate [CO32-] in Overcarbonated Brine

What kind of analyses are you interested in? We are happy to advise!

Questions? Contact us

Metrohm solutions for the chemical industry

Application Note AN-PAN-1005: Chlor-alkali industry: Analysis of Calcium, Magnesium in Brine [pdf]

Metrohm Australia/New Zealand

Please select your topic:

Please select your field of practice:*

Your message:* (required)

Please enter

Your email address*

Title: MrMrsMsDrProf

First Name*:

Last Name*:







Phone Number:

Would you like to subscribe to one or more of our regular scientific publications?

Air Water Soil (email)Chemical and Petrochemical Analysis (email)ElectroChem Matters (email)FoodLab and Beverage Analysis (email)Ion Chromatography News (email)Metrohm Australia Analyst (email)Metrohm Australia Analyst (print)Metrohm Information (print)Mines&Minerals (email)Process Analytics (email)Retsch the Sample (print)Solid Science (email)Teaching and Research (email)

Please enter the displayed code:


Manage your subscriptions