Thesis title: Valorization of phosphogypsum, optimation of hydrometallurgical recovery of Rare Earth Elements and Techno-Economic Analysis of a Full-Scale plant
Phosphogypsum, a widely stockpiled by-product from phosphoric acid production, represents both an environmental challenge and a potential source of valuable rare earth elements (REEs). This study investigates an integrated hydrometallurgical process for REE recovery through sulfuric acid leaching and resin adsorption. Leaching kinetics showed rapid initial REE dissolution followed by slower extraction, with light REEs demonstrating higher recovery than heavy REEs. While resin-in-leach proved ineffective due to possible resin pore blockage due to impurities, post-leach adsorption achieved efficient REE recovery (95% loading in two hours) under optimized conditions.
A techno-economic assessment based on this validated process confirms its commercial viability. For a full-scale plant requiring a €284.30 million capital investment, the annual production of 143,508 kg of mixed REE oxides and 2.19 billion kg of cleaned, marketable calcium sulphate is projected to generate a net profit of €53.88 million, a 19% return on investment, and a payback period of 5.3 years. The study conclusively demonstrates the technical and economic feasibility of transforming phosphogypsum from a waste liability into a source of critical raw materials and a clean industrial product, enabling a true circular economy model.