Valorization of phosphogypsum waste as asphaltic bitumen modifier

Abstract

The accumulation of phosphogypsum wastes from the fertilizer industries, which remain in regulated stacks occupying considerable land resources, is causing significant environment problems worldwide. In that sense, the scientific community is being pressured to find alternative ways for their disposal. In this research, we propose a novel application for phosphogypsum wastes, as a modifier of bitumen for flexible road pavements. Viscous flow tests carried out on bitumen modified with a phosphogypsum waste and doped with sulfuric acid demonstrated an extraordinary increase in viscosity, at 60 ºC, when compared to a counterpart sample which had been modified with gypsum, the main component of phosphogypsum. Similarly, a significant improvement in the viscoelastic response of the resulting material at high temperatures was also found. FTIR (Fourier transform infrared spectroscopy) scans provided evidences of the existence of chemical reactions involving phosphorus, as revealed by a new absorption band from 1060 to 1180 cm -1 , related to C−O−P vibrations. This result points at phosphorus contained in the phosphogypsum impurities to be the actual "modifying" substance. Furthermore, no C-O-P band was observed in the absence of sulfuric acid, which seems to be the "promoting" agent of this type of bond.

Performance and Bacterial Community Shifts During Phosphogypsum Biotransformation

“…High levels of natural radionuclides and metals were also found in these wastes (Binnemans et al 2015). It is estimated that around five tons of this waste is generated per ton of phosphoric acid produced (Enamorado et al, 2014), which exceeds the mass of product, and 100 to 280 ×10 6 ton are produced worldwide (Cuadri et al 2014;Tayibi et al 2009). …”

Utilization of Apatite Ores

“…Potential utilization of phosphogypsum (Fig. 14), the by-product from fertilizer industries, as a bitumen modifier for paving industry was reported by CUADRI et al [68]. It was found that when activated with small quantity of sulfuric acid (0.5 wt.%), the addition of 10 wt.% phosphogypsum leads to a notable improvement in the rheological response of resulting material at high temperatures.…”

Industrial Rejection: Removal of Heavy Metals Based on Chemical Precipitation and Research for Recoverable Material in Byproducts

“…In general, the PG is used in agriculture (for soil stabilization) and construction (preparation of materials for construction / road construction), but in insufficient quantities to absorb all PG generated. The reuse of PG, especially in construction, is based on technical, economic and ecological [40,41,42]. In the world, up to 15% of PG produced is used in construction, in general, used in the production of Portland cement [41].…”