engleski

Waste Gypsum Recycling

Gypsum and its products are all-present in everyday life and their usage results in high waste mass of the material. Gypsum waste demands a special care and disposal due to the possibility of developing toxic and flammable hydrogen sulphur gasses when in contact with organic compounds. The best alternative to special care of the gypsum waste is recycling of the material. In this work the dehydration of waste gypsum from TONDACH d.o.o. factory from Đakovo, Croatia, was studied. Recycling of the waste gypsum has been carried out in hydrothermal reactor in open and closed systems with temperature range from 120 to 190 °C. Heat of hydration of the recovered gypsums was investigated with semi-isoperibol calorimeter and MC CAL micro calorimeter. The waste and recovered materials were subjected to X-ray diffraction analysis (XRD), while recycled material has been examined by Fourier transformation infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XRD analysis in combination with weight loss measurements confirms the start of the dehydration which occurs between 120 and 130 °C. Temperatures higher than 160 °C result in formation of non-reactive anhydride phase. SEM micrographs show morphology changes in correlation with hydrothermal system conditions. The calorimetric results show the successful recovery of waste gypsum where the best results were displayed by samples treated at 130 °C. This research and its results demonstrate that waste gypsum recovery is possible. With further investigation of this topic the reuse of such recycled material in mundane and industrial setting could be achievable.

waste gypsum, dehydration, X-ray diffraction analysis, heat of hydration, calorimetry

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