Direct ammonium sulfate production from untreated industrial phosphogypsum under mild conditions: process evaluation
Year: 2026
Type: article
Abstract: BACKGROUND Industrial phosphogypsum valorization typically requires energy‐intensive pretreatments. This study provides a baseline approach by evaluating direct, single‐step conversion of raw, untreated phosphogypsum into ammonium sulfate and calcium carbonate under mild laboratory conditions (55 °C, 3 h, atmospheric pressure, 1:4 solid‐to‐liquid ratio) using 12–14 wt% NH 4 OH solutions. RESULTS Untreated phosphogypsum demonstrated sufficient intrinsic reactivity to produce crystalline (NH 4 ) 2 SO 4 with a high purity of 96–98.29%, containing 20.31–20.54 wt% nitrogen and 23.03–23.54 wt% sulfur. The highest reaction efficiency and product purity were achieved using a 13 wt% NH 4 OH solution. Due to heterogeneous reaction constraints and mass transfer resistance, the overall conversion efficiency remained moderate at 23.13–29.31%, yielding 1.53–1.93 g of product against a theoretical yield of 6.61 g. CONCLUSION The consistent formation of high‐purity (NH 4 ) 2 SO 4 directly from raw, inactivated phosphogypsum validates the technical viability of this simplified waste‐to‐resource framework. While surface‐related and thermodynamic limitations present clear efficiency boundaries that require future process optimization, the elimination of energy‐intensive pretreatments represents a significant step toward cost‐effective industrial sustainability. This study lays a solid foundation for upcoming pilot‐scale validations, comprehensive mass–energy balances, and integrated CO 2 sequestration strategies. © 2026 Society of Chemical Industry (SCI).
DOI: 10.1002/jctb.70247
Authors: Ertuğrul Çelik, Cemre Avşar Kaya, Suna Ertunç
Institution: Ankara University
Language: English
Subfield: Building and Construction
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
Award: G6758610450
OpenAlex ID: W7171852547