论文部分内容阅读
The phosphogypsum (PG) management policy implemented within the Taparura project in Sfax,Tunisia allowed a reduction of the impact of this residue by finding better waste management procedures with an extremely limited radiological impact.The PG samples used in this study came from a fertilizer factory in Sfax city,Tunisia and were compared to works done on samples from Fertiberia S.A.,Huelva,Spain.This work reviews the impacts associated with the storage and disposition of PG,the confinement procedure carried out to minimize the negative effects of this waste and compares results with those reached by a similar investigation carried out on Spanish naturally occurring PG.The semiquantitative chemical composition of the PG samples was identified.Mineral species were determined by X-ray diffraction.The morphological aspect of the PG was analysed using scanning electron microscopy with energy dispersive spectroscopy (EDS).Natural selected radionuclides belonging to uranium and thorium decay series and 40K present in PG samples have been quantified.The PG samples from Tunisia present a low natural radionuclide levels (30.7 Bq-kg-1 for 238U,188 Bq-kg-1(226Ra),163 Bq-kg-1(2lOPb),12.4 Bq-kg-1 (232Th)) compared to the level of PG samples from Huelva (102 Bq-kg-1 for 238U,520 Bq-kg-1(226Ra),881 Bq-kg-1(2lOPb) and 8 Bq-kg-1 (232Th)).In both cases,the values are below the maximum activity concentrations limits of naturally- occurring radionuclides in common buildings materials and industrial by-products used for building materials in the EU,recommended by the European Commission.The measures carried out within the environment of the site of Taparura after the completion of all excavation and confinement works show no radiological effect.The detected gamma doses are equivalent to the natural level.