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.<p>DOI: <a href="http://dx.doi.org/10.5755/j01.ms.19.2.4438">http://dx.doi.org/10.5755/j01.ms.19.2.4438</a></p

Preparation of α-High-Strength Hemihydrate from Flue Gas Desulfurization Gypsum in AlCl3–MgCl2 Solution at Atmospheric Pressure

“…The effects of metal ions such as Na + , K + , Mg 2+ , Cu 2+ , Al 3+ , and Fe 3+ on the crystal morphology and size of calcium sulfate whiskers in aqueous HCl solutions were also investigated. , The results revealed that Al 3+ ions resulted in bigger and shorter crystals of HH . Additives of succinic acid, sodium citrate, and maleic anhydride proved to be more effective morphology modifiers for crystals of α-HH.…”

“…15,16 The results revealed that Al 3+ ions resulted in bigger and shorter crystals of HH. 16 Additives of succinic acid, 17 sodium citrate, 18 and maleic anhydride 19 proved to be more effective morphology modifiers for crystals of α-HH.…”