Exploring the potential reuse of phosphogypsum: A waste or a resource?

Phosphogypsum (PG), the main industrial by-product of phosphate fertilizer industry, primarily consists of calcium sulfate dihydrate. However, it contains various impurities with variable quantities depending on the origin of the phosphate rock. These impurities can restrict the reuse of phosphogypsum as a secondary primary resource. Consequently, large quantities of produced PG are stored in surface stockpiles that occupy extensive land areas and may pose a significant risk of ecological contamination to the surroundings. Researchers have shown growing interest in addressing the worldwide accumulation of this waste material. To gain a comprehensive understanding of the environmental impact of phosphogypsum, it is crucial to explore its properties (e.g., chemistry, mineralogy, radioactivity), and how it interacts with the surrounding environment, enabling well-informed decisions decision regarding its management and its valorization. In this review, we will i) explore the chemical, radiological and mineralogical characteristics of PG; ii) discuss the environmental concerns related to land discharge and sea disposal; and iii) examine the latest advancements in various valorization techniques developed including agriculture, REE extraction, environmental application, chemical and thermal transformation, and also construction sector. Outlining their limitations and challenges restrict in the global variability of phosphogypsum (PG), technical and economic limitations, and the potential for secondary pollution in select valorization approaches. This requires a thorough assessment and comparison with conventional disposal alternatives.