Production of gypsum plaster from Mae Moh flue-gas gypsum

Abstract

Flue-gas gypsum, from the desulfurization of SO₂ emitting from the Mae Moh power plant, was used as a starting material for the syntheses of β-hemihydrate and multiphase plasters which were used for the fabrication of building plaster components such as gypsum board and projection plaster. β-hemihydrate and multiphase plaster were prepared by calcining the flue-gas gypsum in an electric furnace at temperatures 130℃ and 400-450℃, respectively. The effects of calcining time, particle size of gypsum, temperature and humidity in the furnace upon the phase of plasters obtained and also the effects of various additives additives on the properties of the products were studied. It was found from the experimental results that with the application of the contemporary gupsum technology, the specimens having equivalen quality to those from the natural gypsum could be successfully obtained. The maximum flexural strength of the gypsum board from multiphase plaster was 7.13 ±1.04 N/mm² and that from β-hemihydrate was 5.89±1.48 N/mm². The surface coverage and the initial setting time of the projection plaster were 10.26±0.36 m²/100kg. and 54.53±0.35 min.