Anhydrous Caustic Soda

This product looks like irregular white scales or pearl-like little balls. It is highly deliquescent (it absorbs air moisture and dissolves in it) and has a minimum concentration of sodium hydroxide of 98% in weight, according to the specifications. In Cubatão Plant, it is manufactured as scales and in Bahía Banca Plant, Argentina, it is manufactured as pearls.

In Brazil and Argentina, this product is sold in 25 kg polyethylene sacks, in pallets or in big bags (in Argentina).

Sodium hydroxide is a strong base, popularly used to increase a mixture’s alkalinity or to neutralize acids.

In its anhydrous form, it can be found in two formats: scales or pearls.

Manufacture Process: Cubatão and Bahía Blanca Plants

Anhydrous Caustic Soda derives from Liquid Caustic Soda evaporation process, anhydrous product melting and inlaying process (Soda Flakes). Pearl-like Soda manufacture process is very similar, except for the final step.

Instead of being inlayed, melted soda goes through a completed drilled plate and small liquid spheres are formed, which fall in the tower due to gravity. During the fall, these drops crystalize when they cool down against the current of ambient air in the form of pearls.

Technical information - Physicochemical Features

Chemical formula


Molecular weight


Melting point

318 ºC

Solubility in wate (20 ºC)

109g/ 100g of water

It is neither flammable nor combustible


Flaked Caustic Soda

White scales

Pearls Caustic Soda

White pearls

Boiling point

1390 ºC

Specific weight (20 ºC / 20 ºC)

2,13 g/cm³


It is used in soap and detergents manufacture, ferrous metal surfaces treatment, electrodeposition bath formulation, textiles mercerization, ion-exchange resins regeneration and pH correction in several industrial processes, as food, alcohol and pharmaceutical products.

Technical Information - Download the documents of Anhydrous Caustic Soda

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Sodium Hypochlorite Reactor

 Hypochlorite is produced by a reaction between gaseous Chlorine and a Caustic soda solution being cooled down.


EDC Reactor

EDC (Dichloroethane) is obtained through a reaction between liquid chlorine and ethylene (inserted through a tube) and it is purified by distillation.


Hydrochloric Acid Reaction Furnace

Hydrochloric acid is produced by a controlled combustion reaction of Chlorine and hydrogen, followed by absorption in treated water.



Caustic soda is produced by electrolysis and reduced through the evaporation process.



 Then, the Soda is cooled down and stored in tanks, before being shipped.


(8) Cooling Chlorine

(9) Chlorine Withdrawal

(10) Chlorine Compression

(8) The produced gaseous chlorine is cooled down, (9) dried out and (10) compressed. After being compressed, it turns into a liquid state at low temperature.


(3) Treatment

(4) Filtration

(5) Control

(3) The PICKLE is about eliminating foreign bodies; it is filtered (4) and undergoes a strict control (5) before feeding the ELECTROLYTIC CELLS.


(3) Tratamiento

(4) Filtración

(5) Control

(3) La salmuera se trata para eliminar impurezas, se filtra (4) y pasa por un estricto control (5) para alimentar las CÉLULAS ELECTROLÍTICAS.



If there are salt (sodium chloride) and water in stock, you need to supply our transformers with electricity.


(11) Licuefacción de Cloro

(12) Almacenamiento de Cloro

(11) El cloro en esta forma se almacena en tanques (12) donde se carga en camiones especiales


Sala de Celdas

La ELECTRÓLISIS tiene lugar en la celda. Y así, la energía eléctrica actúa sobre la salmuera y la transforma en SODA CÁUSTICA, CLORO E HIDRÓGENO.

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A Soda Cáustica é produzida na eletrólise e concentrada pelo processo de evaporação.


Cell Room

The ELECTROLYSIS takes place in the cell. This way, electric energy acts on the brine and transforms it into CAUSTIC SODA, CHLORINE AND HYDROGEN.


(3) Tratamento

(4) Filtração

(5) Controle

(3) A SALMOURA é tratada para eliminar impurezas, filtrada (4) e passa sob um rigoroso controle (5) para alimentar as CÉLULAS ELETROLÍTICAS.



Next, prepare the PICKLE obtained from dissolving the salt in the water to use afterwards in the ELECTROLYSIS.