ENVIRONMENTAL SUSTAINABILITY, 2025 (ESCI)
Phosphogypsum (PG) is a by-product generated during the production of phosphoric acid (H3PO4) via the wet process, in which phosphate rock is decomposed with sulfuric acid (H2SO4). Considering the gradual depletion of limited non-renewable resources due to increased industrialization aimed at meeting the demands of a growing global population and rising welfare levels, the evaluation of PG as a valuable resource has become inevitable. In fact, the recovery and reuse of by-products not only contribute to waste reduction but also provide an alternative source of secondary raw materials within the framework of the circular economy. Therefore, this review focuses on PG conversion mechanisms for producing sulfate salts of sodium, potassium, lithium, and ammonium using hydroxide, chloride, fluoride and carbonate media. It also discusses the distribution of various impurities from PG into the resulting salts through these conversion reactions. The industrial significance of the products is emphasized, and effective strategies for PG utilization are evaluated from both environmental and economic perspectives. The study is expected to contribute to the existing scientific literature by presenting a well-organized summary of synthesis routes and by serving as a guide for process optimization and prefeasibility studies.