Recovery and recycling core of phosphogypsum: Characteristic hazardous elements risk assessment and analysis

Abstract

Phosphogypsum(PG) is a solid waste produced by wet-process phosphoric acid. However, the heavy metals and other pollutants contained in PG have not been controlled in the process of resource utilization, and there are potential risks to the ecological environment and human health. In this paper, the basic physical and chemical properties (XRD, XRF, FTIR,TGA and XPS) and heavy metal pollution of four samples from four PG accumulation areas in China were studied. The study found that the microstructure of different samples of PG was not much different, but there were some differences in heavy metal content. The characteristic heavy metals in PG were determined as “As, Cd, Cr and Hg” by comprehensive evaluation methods of different characteristic heavy metals. At the same time, it was found that the valence of heavy metals in PG was related to the process of wet-process phosphoric acid. The harm of gypsum to the environment was mainly caused by heavy metal elements of As, Cd, Cr, Hg. Using the risk exposure model recommended by the United States Environmental Protection Agency, it was found that there were carcinogenic risks for adults and children in soil intake due to As and Cr pollution. Also, the characteristic heavy metals in PG were determined as “As(As3+, As5+), Cd, Cr(Cr3+, Cr6+) and Hg(Hg2+)”. Carcinogenic and non-carcinogenic risks caused by oral intake. Therefore, considering that this was closely related to the long-term accumulation of PG, heavy metals in PG enter the human body through the soil, which causes serious harm to human health. Combined with the above results, the hazard prevention and control model of PG comprehensive utilization was scientifically established from three aspects of hazard identification, risk analysis, and hazard characterization, and the risk control value of PG was determined according to the use scenario of PG. Therefore, this study can provide adequate support for PG's sustainable, efficient, safe, and environmentally friendly utilization.