Characterization and potential industrial appication of gypsum rich waste
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Date
2018-06
Authors
Nur Nadhirah Zailan
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Abstract
NUF Gypsum rich waste which is by product from REE processing was
characterized and analyzed to compare between natural gypsum and evaluate their
quality suitability for specific industrial application. They were analysed by using X-Ray
Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron
Microscopy (SEM), Differential Scanning Calorimetric (DSC) / Thermogravimetric
Analysis (TGA) and X-Ray Fluorescene (XRF) analysis. Other test included pH test,
LOI, moisture, specific gravity and plasticity test are also done. The present characteristic
bond of water vibration at 3606-3558cm-1 and sulfate vibration at 1151cm-1
in FTIR test
indicates the present of gypsum anhydrate (CaSO4.2H2O). The SEM photomicrograph
also shown the presence of hexagonal shape of gypsum and followed by composition of
Calcium Oxide (CaO) and sulfite (SO3) obtained in XRF analysis which lead to formation
of gypsum. The XRD results also indicate the presence of gypsum and calcite phase
crystallinity. The gypsum rich waste is suitable to be used for agriculture and gypsum
board industry since it met all the industrial specification. The high contain of
Magnesium, Mg which is 5.87% is suitable for plant growth as it can act as soluble salt
for the nutrient supply. It also suitable for gypsum board application since the content
would not disturb the hydration process of gyspum board. The content of silica (SiO2)
0.62%, Chlorine (Cl) 2.8% and Na (Sodium) 0.7% meet the specification of agriculture
and gypsum board industry. The iron content in the gypsum waste is quite high for the
high grade of gypsum board application . One of the way to reduce the iron content is by
using organic acid leaching method. Plasticity index value obtained is significantly
optimum which is 19.78 which lead to a good strenght for gypsum board application.