Life cycle assessment for calcination process of flue gas desulfurization gypsum and transformation into β-CaSO4·0.5H2O

Life cycle assessment for calcination process of flue gas desulfurization (FGD) gypsum is carried out at three altered temperatures from 200 to 600 °C for transformation into β-CaSO 4 ·0.5H 2 O without chemical treatment. Physicochemical characterization of obtained FGD gypsum are performed by standard methods to recognize the physical and chemical properties, identification and quality of the material for further analysis. Effect of calcination on particle size distribution of FGD gypsum is studied along with mineralogical, compositional and morphological analysis by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS), respectively. Calcination process has slightly reduced the particle size and improved microstructure of FGD gypsum. Aspect ratio of calcined FGD gypsum samples is reduced from 2.40 to 1.32 due to crack bursting at high temperature and removal of hydroxyl functional group. Environmental impact of calcination process is evaluated by life cycle assessment method using openLCA software and ecoinvent database in conformance with ISO 14040–14044. System boundary covers stages of procedure with cradle-to-gate approach. Production of β-CaSO 4 ·0.5H 2 O powder by calcination at 200 °C exhibited minimum environmental impacts with 25.5 kg of CO 2 eq emission, responsible of GWP. FGD gypsum has transformed into β-CaSO 4 ·0.5H 2 O via frugal and easy method for construction applications with geometric microstructure, which offers high mechanical strength with better workability. Present study will provide referential data set for FGD gypsum without chemical treatment and life cycle data of its calcination process. This will be supportive for reutilizing FGD gypsum in value-added sustainable construction materials as there is a dearth of reliable data on characteristics of FGD gypsum and its environmental impacts. • Calcination improved the microstructure and reduced aspect ratio of FGD gypsum. • Calcination has transformed FGD gypsum particulates into β-CaSO 4 ·0.5H 2 O. • Calcination at 200 °C exhibited lesser environmental impacts than 400 °C and 600 °C.