ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Microwave-assisted decomposition of fgd gypsum in the presence of magnetite and anthracite

Zhong-Hai Ji, Yu Guo, Jin Chen, Li-Na Guo, Bo Yang, Xue-Fang Zhang, Ling-Jia Meng, and Li Qin

College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024, China

E-mail: chenjin2013815@126.com

Abstract: Decomposition of flue gas desulfurization (FGD) gypsum in the presence of (10 mass %) magnetite and different mass fractions of anthracite, as a reducer, has been investigated under microwave irradiation in air atmosphere. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the decomposition residues. Both experiment results and theoretical analysis indicated that the optimum amount of anthracite added to the FGD gypsum (10 mass %) magnetite mixture was 8 mass %. Under optimum conditions, the maximum desulfurization degree after microwave treatment for 60 min at 1000°C was 93.86 %. Due to microwave heating and calcium ferrite formation, the decomposition temperature of FGD gypsum decreased to around 800°C in air atmosphere. Based on the XRD patterns and SEM images, the reaction of CaSO₄ with the additives occurred from the centre to the surface where the liquid phase was generated under microwave heating. SEM images also showed a lower amount of the liquid phase in the outermost layer samples, which prevented the formation of a kiln ring under microwave heating.

Keywords: FGD gypsum – magnetite – microwave heating – desulfurtion degree – calcium ferrite

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2016-0071

Chemical Papers 70 (10) 1399–1407 (2016)