The processing of the Gafsa phosphate is carried out in Tunisian plants exclusively by the SIAPE method of wetprocess dehydrate phosphoric acid manufacturing. This process was developed by SIAPE some fifty years ago at its own plant using its own expertise and it is constantly being improved. The main advantages of the SIAPE PROCESS are :

adaptability to all grades of phosphate
low investment and production costs
easiness of operation and use of a single
     driving engine reactor
high  P2O5 recovery from the phosphate
     ore.

Phosphoric acid is produced from Gafsa phosphate without preliminary grinding thanks, to the ore’s reactivity and the specific advantages of the SIAPE PROCESS which ensures :

appreciable savings in energy
reduction in operating cost.
ecologically sound working conditions through dust elimination.

Because of its extensive experience in the phosphate industry, fertilizer producers from all over the world frequently ask the GCT for technical assistance, reconversion of existing facilities, and new project conception.

A Second "SIAPE process" was developed by SIAPE for TSP production.

Both "SIAPE processes" are regularly up-dated and improved, and they are used in a number of countries including Greece, Turkey, Romania, Bulgaria, Poland, and Syria. The merchant grade phosphoric acid is produced in two sites : GABES and SKHIRA.


This site is composed of 5 Phosphoric Acid producing lines of weak Acid "28% P2O5".

3 lines at Gabes Phosphoric Acid Plant :

  • One Line of 310 tons P2O5 / day
  • One Line of  400 tons P2O5 / day
  • One Line of  500 tons P2O5 / day

The P2O5 concentration of the Merchant Grade Phosphoric Acid (MGA) is 54% P2O5. The annual production is reaching 0.47 million tons of MGA "54% P2O5".

2 lines at Gabes DAP Plant  with a capacity of  580 tons of P2O5 / day /  line

The annual production capacity of Merchant Grade Phosphoric Acid "54% P2O5" is 330000 tons of P2O5. After revamping, capacity production is 405000 tons of P2O5 / year.

In the sulphuric acid required to produce this phosphoric acid is manufactured in :

  • 4 units at the Gabes Phosphoric Acid Plant, with a total daily capacity of 5400 tons of  H2SO4,
  • 2 units at the DAP Plant with a total daily capacity of 3000 tons of  H2SO4.


The industrial site of Skhira, the most recent facility (1988) of the GCT comprises :

2 lines producing Phosphoric Acid "28% P2O5" 
with a capacity of  550 tons  P2O5 / day / line.
 4 lines to concentrate  diluted acid into MGA "54% P2O5"  
 with a capacity of 300 tons of  P2O5 / day / line.

The annual phosphoric acid production capacity : 375000 tons of P2O5. 
In the sulphuric acid required to produce this phosphoric acid is manufactured in 2 lines, with a capacity of 1750 tons H2SO4 per day / line.


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