Brine Purification

Brine Purification

Raw salt contains inorganic impurities such as calcium ion, magnesium ion, sulfate and also bacterium, algae and mechanical impurities.
Those impurities, if not removed, will enter brine system and damage ion-exchange membrane resulting in decreased electrolysis efficiency and shortened life-time of membrane.
In order to meet the requirement of brine qualification, impurities will be removed in primary filtration process and secondary filtration process.

Primary brine filtration system

The mainstream technology utilized in primary brine filtration system is membrane process with output parameters of brine as following:


NaCl (KCl)                305 ± 5 g/L

Ca2+  + Mg2+           ≤ 1 ml/L

SS                             ≤ 1 mg/L


BLUESTAR / REWINZ can provide both inorganic and organic membrane technologies for clients respectively by different membrane material and process.


Ceramic Membrane Method (Inorganic Membrane)

Ceramic membrane is a kind of dissymmetrical membrane produced with a specific process under 1600°C by high-purified inorganic ceramic material, it turns up with a condition of tubulous and multi-tunneled.

Advantages of Ceramic Membrane filtration system:

– Short procedure, simple process, easy to technically modify and minimized space requirement.

– Precise filtration and steady brine quality.

– Long life-time of membrane, higher strength, easy clean-up and regeneration, minuteness filter diameter: 50 nanometer.

– Handling with high magnesium contained raw salt and contamination-proof.


SST Membrane Method (Organic Membrane)

The organic membrane is originally inspired by artificial vascular technology. It is manufactured by special drawing process with an excellent physical and chemical performance of PTFE membrane. The aperture on membrane is approximately between 0.22 µm and 0.5 µm.

Advantages of SST Membrane filtration system:

– Simplified processing, shortened procedure, minimized requirement according to space and cost-effective.

– High quality outlet-brine and fully automatic control.

– Easy to clean-up and no waste liquid generated and discharged.

– Excellent performance and longer life-time of new type anti-polluting SST membrane.



Membrane Method to De-sulfate + High Performance Gypsum α-CaSO4•0.5H2O

It is needed to add sodium sulfite to remove free chlorine in depleted brine after electrolysis process, which would result in increased SO4 2- concentration in brine. In traditional process, BaCl2 is utilized to remove SO4 2-; in latest technology membrane method is supplied to remove SO4 2-. Low content sulfate solution would flow back to salt-dissolving process, while high content sulfate solution would be used to produce Na2SO4 * 10H2O, and in latest process can be used to produce high intensity gypsum α-CaSO4•0.5H2O improve additional value.


Technical Indexes of Membrane Method To De-Sulfate

De-Na2SO4 ability:                                                                     100~400 kg/h

SO4 2- concentration in depleted brine:                                 ≤ 7 g/L

SO4 2- concentration in low content sulfate solution:        0.11~0.2 g/L

SO4 2- concentration in high content sulfate solution:      40~70 g/L



Advantages of Membrane Method to De-Sulfate:

– Zero discharge, energy saving, high additional value

– Pre-treatment Process can keep a good brine index and make membrane a long term stability.

– High performance MRO membrane, large through flow, high reject rate, high anti-pollution performance, long term stable operation.

– Special heat exchanger by own intellectual properties, effectively solve sodium sulfate crystal blocking issue.



Secondary Brine Filtration System

The brine after primary brine filtration process is unable to match the requirements of elecrolyzer yet, which needs to be purified by following secondary brine treatment process to further remove the content of Ca2+ and Mg2+ until less than 20ppd, so as to make brine reach electrolyzer’s requirements.
Chelate Resin Column is used to remove high-valent metal ions inside primary brine section, and make purified brine indexes reach membrane electrolyzer requirement.


Technical Indexes:

Outlet Brine (Ca2+ , Mg2+): Less than 5ppb


Advantages of our Secondary Brine Filtration System:

– Module technique, provided more than 100 sets of facilities for customers.
– Minimized space requirement, save investment.
– Supply in modularization, decreased installation work on spot.
– Provide design, manufacturing, installation and commissioning service.

Your System Supplier for Complex Solutions

Whether it is components, systems or complete turnkey solutions “as a service”: Let our chlor-alkali and bulk material experts advise you on your challenges.