Phosphogypsum valorization through circular economy processes: review of the state of the art and perspectives from the FIC-FIGHTERS project

Phosphogypsum is a by-product of the wet production process of phosphoric acid from phosphate minerals. Since the 1950s, many industries in Europe used this process to produce fertilizers and detergents. Processing residues and waste were often dumped near production facilities or dispersed in sensitive areas such as river estuaries or coastal lagoons, resulting in the release of toxic substances into the environment and damage to the ecosystem. In Europe, to this day, there are still many areas with non-contained phosphogypsum deposits, which pose significant environmental, social and economic problems. Phosphogypsum is mainly composed of a calcium sulfate matrix and contains natural radionuclides (mainly 226 Ra, 210 Pb, 210 Po) in different concentrations, depending on the composition of the starting mineral; it can also contain elements such as phosphorus and fluorine, heavy metals as zinc, copper, chromium, cadmium, and some rare-earth elements (REEs). From the perspective of circular economy, it is therefore increasingly considered a resource from which it is possible to extract new raw materials. In this work, the main options currently under study for the valorization of phosphogypsum through circular economy processes are evaluated and the activities planned within the Horizon Europe Fic-FIGHTERS project are presented.