Decomposition of the gypsum samples occurs at higher temperature ranges than plaster of paris or hemihydrate samples. For the former, in DTA curves obtained at higher heating rates, decomposition occurs from 100°C to about 300°C, with overlapped peaks of the two steps 3, 6, 7.
Factors affecting IBP gypsum decomposition have been elaborated in previous studies, and include the atmosphere (Mihara et al., 2007), ... TG, DTG, and DSC curves of pure gypsum. The dehydration process can be neglected, as the current study is focused on the thermal decomposition of anhydride. The decomposition of anhydride …
NOV.1985 Thermal Analysis of Gypsum 1. Introduction Gypsum has long been used as a building material and is used for that purpose in the following items. • Setting retarder for Portland cement • For gypsum plaster, gypsum board, ceramic molding tools, and arts …
The decomposition of CaSO 4 · 2H 2 O under the conditions of TA consists of two consecutive reactions, firstly CaSO 4 · 0.5H 2 O then CaSO 4 III being formed. …
Milobowski et al. [16] conducted a similar study of wet FGD products and analyzed the distinct decomposition curves of four pure Hg compounds. However, clear characteristic temperatures of HgS and HgO cannot be identified because the curves of these two compounds overlapped each other.
The results indicated that the factors of the final reaction temperature and the reaction atmosphere have significant influences on the decomposition of gypsum, in the condition of 850-1050 °C ...
This explains the decomposition of gypsum at different forms of calcium sulphate dihydrate (CaSO 4 ·2H 2 O) ... In the TG/DTG curve for sample YXT2 ( Fig. 2 (b)), a slight weight loss ...
This explains the decomposition of gypsum at different forms of calcium sulphate dihydrate (CaSO 4 ·2H 2 O) to calcium sulphate anhydrite (CaSO 4 ) between 85 to 400 • C [38,39, 41], which is ...
Studies suggest that the peak in the specific curve around 700-800 °C corresponds to the decomposition of the calcium carbonate and magnesium carbonate content of the gypsum boards, and their ...
The thermal decomposition of limestone and gypsum by concentrated solar radiation was studied. A 1.5-kW solar furnace was used to obtain the required reaction temperature. ... The decrease in the slope of each curve at longer reaction times implies a drop in the reaction rate. This may also be due to the formation of a cal- cium oxide layer ...
The fast mass transfer between the gas and solid, long residence time and extensive heat transfer are benefit for gypsum decomposition, while, the original size of the gypsum is too fine to well fluidized and easily entrained out the reactor. ... Thermogravimetric curve with 0% CO. Full size image. Fig. 3. Thermogravimetric curve …
Gypsum wallboard has been used for over 100 years as a barrier to the spread of fire in residential and commercial structures. The gypsum molecule, CaSO 4 …
The obvious decomposition occurs at the temperatures corresponding to peak points. The first peak appears at 125.1 °C, which corresponds to dehydration in the 1 st stage. The smooth DTG curve in the temperature range of 200–600 °C corresponds to the slow weight loss caused by decomposition of hydrates and arsenites in the 2nd stage.
The course of the weight losses is described by the thermogravimetric curves (Fig. 3). The weight loss of all the materials from the beginning to 220 °C is caused by the loss of residual free water and dehydration of the dihydrate to anhydrite III. ... On the TG curve of the binary (gypsum-lime) binder, the decomposition of residual calcium ...
The relationship between separation time and the Hg compounds in gypsum. The thermal decomposition curves of Hg compounds in the FGD gypsum are shown in Fig. 8. After resolving overlapping peaks by using PeakFit v4.12, different mercury species can be identified.
on TG-DTA curves and Coast-Redfern method. The apparent activation energy of FGD gypsums was much lower than that of AG. The apparent activation energies of tested AG, ... temperature and the reaction atmosphere have significant influences on the decomposition of gypsum, in the condition of 850–1,050 C, the total decomposition …
Figure 1 shows the TG and DTG curves of a high-purity gypsum sample. As thermal decomposition is occurring in an open pan, the steps represented by Eqs. 2 and 3 occur simultaneously and respective DTG and DTA peaks actually are overlapped. This fact is characterized by the shoulder, which occurs in both DTG and DTA curves at …
The thermal decomposition profiles for the gypsum samples were found different for both power stations A and B (Fig. 2).In general, the thermal decomposition of Hg compounds in gypsum samples occurs at low temperature ranging from approximately 100 to 250 °C.The FGD-A (Fig. 2 a) shows multiple but convoluted peaks with a …
The endothermic peak with obvious weight loss at 674.7 °C was attributed to a decomposition of calcium carbonate, that is known as one of additives in waste …
Weight loss (TG) and derivative weight loss (DTG) curves are presented in Fig. 4. Five main thermal events were observed in all the samples. At the temperature interval 50–300 °C, two major endothermic peaks are distinguished at approx. 120 °C and 140 °C correspond to thaumasite and gypsum decomposition, respectively [31].
On the other hand, the decomposition TG curve of natural gypsum begins at 62°C and ends at 190°C and gives no indication of discontinuity during dehydration. Decomposition of the gypsum samples occurs at higher temperature ranges than plaster of paris or hemihydrate samples. For the former, in DTA curves obtained at higher …
Fig. 9 (b) illustrates the X-ray Diffraction (XRD) curves for the decomposition products of two distinct types of gypsum under the conditions of 2% H 2, 20% CO 2, and 1050 °C. The XRD curves of the reduction decomposition products of desulfurized gypsum and phosphogypsum exhibit smooth profiles, indicating a reduced …
The Hg release curves (Hg t) generated by thermal decomposition of the seven FGD gypsum samples are shown in Fig. 4. By integrating the peak area of each Hg release curve, the recoveries of Hg were calculated, which represented the ratio of mercury released to the total mercury content in the tested FGD gypsum (as shown in Table 3). …
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The first curve (after 2 h) shows very little Ca(OH)2 and much more CaC03, besides unreacted gypsum. The second curve (after 4 h) shows more Ca(OH)2, but a large amount of CaC03 and unreacted gypsum was present. Finally the third TG curve from a sample after 46 h KOH treatment, only shows the decomposition steps of …
Thermal behavior of synthetic gypsum. The thermal curves of the as-prepared gypsum obtained under nitrogen flow at 10 °C min −1 are illustrated in Fig. 1. The TG curve shows a total mass loss of 20.7% in the temperature range between 120 and 180 °C, which corresponds to the loss of two molecules of structural water (theoretical mass loss is ...
Gypsum to Gypsum aims to make our pricing cost-effective and saving our customers one average 30% less than landfill or transfer station rates. ... end product. Our Culture & Mission. Gypsum to Gypsum is made of people who are deeply committed to staying ahead of the curve when it comes to best practices around the collection, processing, …
A kinetic study has been undertaken of the thermal decomposition of naturally-occurring gypsum and pure calcium sulphate dihydrate. The reaction proceeds without any evidence of detectable melting. ... The mass loss and DSC curves for the dehydration of natural gypsum at 5 min-' in an inert atmosphere. 488 D.L. Hudson …
Gypsum (construction Gypsum, CaSO 4 ·2H 2 O) donated from the private collection. ATR-FT-IR spectrum in the region of 4000-225 cm –1 Institute of Chemistry University of Tartu, Estonia
The dependence of the decomposition of kaolin, limestone and gypsum, on heating rate m and sphere diameter L is investigated. It is shown that the shape of the TG curve and the temperature of maximum reaction rate T m are changed significantly as m and L vary. In this way information about the rate-controlling process is obtained.
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