ABSTRACT:

The accumulation of phosphogypsum (PG) produced till 2015 makes its management a real challenge to the Tunisian authorities and puts the Chemical Tunisian Group (TCG) to face a challenge at large scale as the specified storage embankments knew considerable extensions in terms of heights and areas. Several studies were elaborated subsequently in 2007, 2012 and 2013 to focus on the stability of Sfax and Skhira Phosphogypsum embankments' and showed two different chemical and mechanical behaviors according to the experienced deposition process. In 2012, it was revealed that the wet PG embankment of Sfax City with 56m height, 53Ha area and 32° slope can only be of 70m height maximum. This embankment can reach 100m in height if a reinforcement technique will be used. This deposition process is well recommended to ensure better interaction between the embankment and the existing ground surface. Using the dry deposited process, the area of the PG embankment of Skhira City covers 112 Ha and presents two elevation levels of 25m and 55m in 2013. However, the dry deposited process results in a damaged embankment profile, excessive settlements and lateral displacements. Therefore, a PG embankment of 100m height cannot be achieved. A reinforcement of the embankment by High Density Poly Ethylen geotextile layers of a rigidity modulus of 19MN/lm at increments of 4m from 55m from land allows reaching 130m of height. For technical reasons, a comparative study was raised between the wet and the dry process and lead to interesting conclusions in favor of the wet process from both industrial and geotechnical concerns. Thus, the TCG expects turning all its deposition processes to the wet one. This work aims at presenting a synthesis of the studies investigated to focus on the stability of Sfax and Skhira PG embankments as well as the actual challenges of PG storage.

This content is only available via PDF.
You can access this article if you purchase or spend a download.