TY  - CONF
A1  - Stawski, Tomasz
T1  - Towards sustainable solution-driven recycling of gypsum
N2  - Gypsum (CaSO₄·2H₂O) is a crucial mineral across sectors such as construction, agriculture, and biomedicine. Despite its potentially full recyclability, a shortage looms due to limited mining in Europe and decreasing production of flue gas desulfurization (FGD) gypsum, a byproduct of coal power plants. With current EU consumption at 24 MT/a (17 MT mined, 7 MT FGD), a deficit of 10-35 MT/a is projected by the 2030s as CaSO₄ becomes a critical raw material [1]. Meanwhile, substantial CaSO₄ waste is produced in various industries (e.g., phosphogypsum, red gypsum), but its recycling remains limited (10% in Germany, 5% in the EU) due to contamination and separation challenges.

This contribution introduces a sustainable, efficient wet-chemical method for converting gypsum to bassanite (CaSO₄·0.5H₂O), and thus recycling gypsum, under mild conditions (T < 100 °C) using reusable high-salinity aqueous solutions (brines with c[NaCl] > 4 M) [2]. The optimal conversion conditions (T > 80°C, c[NaCl] > 4 M) enable rapid (<5 min) and reversible transformation (Fig. 1). Upon cooling, gypsum re-forms, offering a temperature-dependent control over phase transition. Unlike conventional thermal dehydration (150-200 °C), this approach promotes the dissolution of gypsum, allowing contaminants to be separated via selective precipitation or adsorption. Additionally, the wet-chemical process facilitates the physical removal of impurities from gypsum matrices, making it advantageous for recycling gypsum waste from sources such as demolition or urban mining, where it is often mixed with other materials.

Our approach presents a sustainable pathway for recovering high-purity bassanite from contaminated gypsum waste, aligning with EU goals for resource conservation and waste reduction.
T2  - MaterialsWeek 2025
CY  - Frankfurt am Main, Germany
DA  - 02.04.2025
KW  - Gypsum
KW  - Calcium sulfate
KW  - Recycling
PY  - 2025
AN  - OPUS4-64677
LA  - eng
AD  - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER  -