a-Hemihydrate Gypsum from Flue Gas Desulphurization Gypsum

Abstract

In this work, properties of sulphate technogenic raw material – flue gas desulphurization (FGD) gypsum have been investigated in order to obtain α-hemihydrate gypsum as gypsum binding material. FGD gypsum is produced as a by-product during the process of desulphurization of exhaust gas emitted in power stations heated by fuel containing sulphur. It has been determined that α-hemihydrate gypsum can be obtained from FGD gypsum under hydrothermal conditions at 125 °C and 130 °C. The compressive strength of gypsum samples is 13 MPa – 16 MPa after 2 h of hardening and it depends on temperature and time of isothermic curing. The compressive strength of the same samples in dry state is 49 MPa – 67 MPa. SEM analysis data showed that the properties of α-hemihydrate gypsum significantly depend on the shape and size of its crystals: when crystals have near form to regular hexagonal – shaped prism with length and width ratio approx. of 4 : 1, the gypsum exhibits the high quality mechanical and physical properties.

DOI: http://dx.doi.org/10.5755/j01.ms.19.2.4438