Research advancements in phosphogypsum crystal modifiers

Abstract

The excessive demand for phosphorus-based fertilizers is contributing to the undesired byproduct of phosphogypsum (PG), typically found in large quantities in phosphoric acid industry. Without proper management, this industrial waste poses a significant environmental pollution risk. Current technologies are struggle to effectively handle the volume of PG produced, but one promising solution is its conversion into hemihydrate gypsum (CaSO₄·0.5H₂O, HH). HH can exist in two phases, α-HH and β-HH, with α-hemihydrate gypsum (α-HH) being preferred for its complete crystal structure and lower water requirement for hydration. The morphology of α-HH gypsum is crucial for its material applications, and controlling crystal morphology is possible through the use of suitable crystal modifiers. This review explores various aspects of crystal modifiers and highlights their role in the preparation of α-HH from PG. It suggests that leveraging the interfacial properties of PG could lead to innovative applications. Additionally, the review outlines future directions for PG development and identifies challenges to be addressed in the next steps.

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