EXTRACTION OF ANHYDROUS SODIUM SULPHATE :

The anhydrous sodium Sulphate production plant was built during the period 1989 – 1991. It covers an area of 1500 square meters, and it constructed on four levels connected through steel staircases, both from inside and outside. The plant includes the production, packing and storing units. In the following lines we present the main features of the process.

The industrial process starts with the preparation of the concentrated solution ( the brine ) which is then pumped through vertical pumps into the sodium Sulphate plant.

The concentrated solution coming into the plant is cooled from 25ºC to 15ºc using plate heat exchangers where the cooling agent is the mother liquor from the salt separation stage.

3) Fractional Crystallization To Produce Hydrous Sodium Sulphate Glauber Salt ( Pre-Cooling Of Feed Brine ): .

The fractional crystallization of hydrous sodium Sulphate precipitates at temperature < 15ºC. through cooling of the concentrated solution in two steps

-Step one ( cooling of the feed brine )
The solution is cooled from 15º C to 12º C to precipitate hydrous sodium Sulphate crystals more than 99% pure. The solution is cooled through the heat exchanger (the cooling agent is the mother liquor from the salt separation stage.

Step two : ( cooling of feed brine )
The same as step one except that the cooling agent is glycol solution (30%), cooled down to 1º C by two big refrigerators ( 1 megawatt capacity each ) for the extraction of Glauber salt.

4)Glauber Salt Production:

Crystals are separated through their accumlation at the bottom of a thickener in which the suspension of Glauber salt is centrifuged at temperature Oº C. The thickener is supplied with a scraper to help crystals settle down. The liquid is used as a cooling agent for other units.
Melting of Glauber salt is achieved at 50º C to produce anhydrous sodium sulphate crystals.

5)Separation of Anhydrous Sodium Sulphate Crystals :

This is done by pumping the suspension ( crystals + saturated solution ) into 3 centrifuges where the anhydrous crystals are separated and flow to a fluid bed drier. The lean solution ( mother liquor ) flows to a collecting tank.

The anhydrous crystals are now dried and cooled in a vibrating fluid bed drier / cooler . Drying is effected by hot air at 60 Cº using steam generators but cooling is induced by cold air at 20 Cº where water / glycol mixture from the refrigerating machines is used.

6)Evaporation Of The Mother Liquor :

Mother liquor after Na2 SO4 separation is pumped from the collecting tank to 3 multiple effect evaporators. Each of these is equipped with a heat exchanger and circulation pump.
The evaporators work under vacuum created by a condenser and vacuum pump. Triple effect vaporization at 100 Cº , 82 Cº and 65 Cº on the mother liquor then Na2SO4 crystals from centrifuge unit are dried and moisture of Na2SO4 crystals is < 0,1 %.

7)Packing Of The Final Product :

The produced anhydrous and dry sodium Sulphate is automatically transported to 3 storage silos, 100m³ capacity each, with a conveyor belt, crushers and sieves . There, it is packed according to the requirement of the customer. The unit hosts three automatic packing machines to pack the product as follow :

• In polyethylene bags, 25 or 50 kg net weight each.

• In woven polypropylene bags, 50 kg net weight each.