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CAUSTIC SODA RECOVERY: CRYSTALFIX

Christalfix is the most updated technology for the recovery of caustic soda used in the process of dies pickling by the aluminium extrusion industry.

Crystalfix allows for a vast array of advantages under any aspect (economical, environmental, safety) of the use of caustic soda for dies pickling

The Use of Caustic Soda for Dies Pickling

In the aluminium extrusion industry, dies are cleaned by dipping them into a caustic soda solution, which dissolves the aluminium metal.

With the traditional method, in order to keep this process efficient, the caustic soda needs to be frequently replaced, since it rapidly gets enriched in aluminium content. 

For this reason, the traditional method generates several problems, such as: 

·Non-efficiency of the process

·Cost for the fresh caustic soda

·Cost for the disposal of spent caustic soda

·High risks related to the temporary storage of large volumes of aggressive chemicals 

·Unfriendly environmental approach

The Functioning of Crystalfix

CRYSTALFIX is a caustic soda recovery system, which consists of a flow treatment for controlling the aluminium concentration of caustic etch solutions. 

This is done by removing the dissolved aluminium as aluminium hydroxide and thereby recovering the caustic soda chemically active.

The caustic soda is completely recovered, with the only exception of small losses due to the drag-out into rinsing tanks or plant washing during usual maintenance operations.

The caustic soda recovery process consists of a closed loop connected to the die-cleaning system. The loop is made of a regeneration module with a filtration system:

·The crystallizer contains a slurry of aluminium hydroxide and etch solution which provokes continual precipitation of the dissolved aluminium from the etch solution.

·The centrifuge filter removes a controlled percentage of solids from the slurry.

The outgoing product is a caustic soda solution, which can be concentrated with new caustic soda in flakes or pearls or concentrate liquid.

The advantages

The advantages connected with the use of Crystalfix are many, and involve all the aspects of dies pickling technology:

·Costs saving for the non consumption of caustic soda

·Costs saving since there is no need of waste disposal of spent caustic soda

·Aluminium hydroxide powder can be disposed as non-toxic waste or can be sold

·Easier process control and higher efficiency

·Minimizes the volumes of chemicals to be stored

·Environmental friendly approach of the dies cleaning process