Stabilization of phosphogypsum by sulfur polymer

In this research, a new type of phosphogypsum-sulfur polymer cement (PG-SPC) for use in the manufacture of building materials was obtained. Physicochemical, radiological characterization, and modeling of exhalation rates were carried out in phosphogypsum (PG) and PG-SPC samples. Because the PG is enriched in several natural radionucleides, a leaching study in PG-SPC was performed. The optimized ratio of elemental sulfur=phosphogypsum 1/4 1:1.0 and phosphogypsum dosage = 10-40% by weight was obtained. The result showed that the solidified materials present a highest strength (54-62 MPa) and low total porosity (2.8-6.8%). The activity concentration index (I) in the PG-SPC is lower than the reference values in most international regulations; therefore these new sulfur polymer cements can be used without radiological restrictions in the manufacture of building materials inside a standard room (5 × 5 × 2 m3) with good ventilation. The leaching experiment demonstrated that the environmental impacts of the PG-SPC cements are negligible.