In order to study the physical and mechanical properties of gypsum rock samples in three states (natural, high-temperature dehydration and hydration time), natural gypsum rock was put into high-temperature condition of 220°C for dehydration treatment, and then the high-temperature dehydrated gypsum rock was treated with different …
The dehydration process of gypsum rock was studied under concentrated solar energy by using a Fresnel lens with power density of 260 Wcm 2. Temperatures higher than 700 C were attained for 1 min ...
At 2.5 GPa, gypsum starts to dehydrate around 428 K, by forming bassanite, CaSO 4 hemihydrate, which completely dehydrates to γ-anhydrite at 488 K.
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The dehydration of gypsum CaSO 4.2H 2 O has been studied, at negligible water vapour pressure, by in situ infrared (IR) spectroscopy and by thermogravimetry to determine whether intermediate phases (CaSO 4. n H 2 O) exist, other than the hemihydrate with n =0.5, and also to compare the mechanism of the dehydration process when measured …
during dehydration. In particular, Popp and Kern [1993] observed dramatic decreases in V P, V S and Poisson's ratio during experimental dehydration of lizardite and gypsum. [3] Two challenging problems encountered in addressing the possible importance of dehydration embrittlement in 1Laboratoire de Géologie, École Normale Supérieure, …
Abstract. The dehydration of pure and waste gypsums has been examined using in situ synchrotron angledispersive X-ray diffraction. Pure gypsum was studied …
dehydration products of gypsum. Of particular interest in our context is the work of Bensted and Prakash (1968) who investigated the possibility of the existence of two forms of hemihydrate (c~ and/3), but concluded that there are only three dehydration products of the dehydration of gyp-
The thermodynamic calculation results reveal that γ-CaSO4 has an extraordinary ability to capture water molecules from an extremely dry atmosphere, which is very useful in some fields, such as in drying processes and even for extracting liquid water fromextremely dry atmosphere. The dehydration products of gypsum under different …
RESEARCH RESEARCHCOMMUNICATIONS COMMUNICATIONS In situ micro-Raman investigation of dehydration mechanism in natural gypsum P. S. R. Prasad†,*, A. Pradhan‡ and T. N. Gowd† † Mineral Physics …
In this work, the dehydration pathways of gypsum and the rehydration mechanism of soluble anhydrite were mainly investigated by thermodynamic modeling …
An in situ dehydration kinetics study of gypsum under water-saturated condition was performed in the temperature and pressure ranges of 383–423 K and …
Mineralogical Magazine, June 2009, Vol. 73(3), pp. 421–432 Structural evolution during the dehydration of gypsum materials S. D. M. JACQUES1,*, A. GONZÁLEZ-SABORIDO1, O. LEYNAUD1, J. BENSTED1, M. TYRER2, R. I. W. GREAVES2 AND P. BARNES1 1 Department of Chemistry, University College London, 20 Gordon Street, …
ture at which the dehydration events occur increases (T dehydration = 425.5 K in an open system, T dehydration = 439 K in a sealed system, in the presence of excess water). Compared with the wealth of high-temperature studies available, there is a lack of experimental studies on the gypsum-anhydrite dehydration reaction sequences at
(a) Surface plot of angle-dispersive diffraction patterns (collected at station 6.2, SRS, UK, using a wavelength of 1.4000(2) A ˚ ) obtained during the dehydration of a pure gypsum system within ...
The gypsum dehydration capability determined under the given test conditions of about 26% in the vertical stirred media mill can be considered as relatively low compared with the dehydration capability of ball mills (up to ). Comparable grinding trials in a semi-industrial horizontal SMM have shown that with fairly long operating times ...
The microstructures formed by the dehydration of gypsum under controlled conditions of temperature and water vapor partial pressure were characterized using in …
Oman: Oman exported 11.2Mt of natural gypsum from its Port of Salalah in 2023, up by 11% year-on-year from 9.9Mt in 2022. Zawawi Minerals has reported that the main destination for exports was …
Key Points. Dehydration of gypsum in drained conditions induces a decrease in Vp and Vs. Acoustic emissions indicate pore collapse. Poisson's ratio …
The microstructures of a set of samples containing bassanite and gypsum from dehydration experiments on Volterra gypsum have been analysed by conventional transmitted light microscopy and electron ...
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"Going forward, importing countries will be increasingly looking to the Sultanate of Oman to meet their gypsum requirements. At the current rate of growth in exports, Oman's share is projected to rise to around 48 - 50 per cent of demand, which equates to over 130 million MT over the 2022- 2031 timeframe." ...
Oman Gypsum quarry is located 19 km South of Thumrait city, Salalah. Thumrait is the nearest city. Quarry is located 4 Km (well graded road) away from the Muscat- Salalah dual carriage main highway. Nearest sea port for shipment is Salalah Port. This is well connected with high quality road network of Oman. Salalah Port is located 82.0 Km from …
The Simulation and Analysis of Dehydration Process of FGD Gypsum Grouted Wall: ZENG Ziyue 1,2, YANG Jiansen 1, WEI Yongqi 2: 1 School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, Ningxia, China 2 School of Material Science and Engineering, Tongji University, Shanghai 201804, China
Thermo-poro-mechanics Modelling of Gypsum Dehydration 179 1 mol of gypsum Intact Gyp- sum Sample 1 mol of bassanite porosity 1.5 mol of water Reaction products excess Expelled w ater Fig.1. Illustration of the reaction (1) of gypsum into bassanite and water after a temperature increase up to 388oK. 1mol of Gypsum (molar volume 74.69cm3 …
Diagram 1 - Dehydration. The first process is the formation of hemihydrate or anhydrite from dihydrate. To obtain more information about this step, gypsum crystals were grown from sodium sulphate and calcium chloride via a diffusion process. A large test tube, approximately 200mL in volume, was filled with 3g of sodium sulphate (Na 2 SO 4).
Table 3 Average value of the activation energy of gypsum dehydration for the steps, which can be seen in Fig. 4 E/kJ molŒ1 216 184 238 117 αstep 0.08Œ0.24 0.24Œ0.51 0.52Œ0.72 0.72Œ0.92 Step number I II III IV The first step, in the range of the low values of αis characterised by relatively
The spectral behavior of gypsum dehydration in the visible to near-infrared (350–2500 nm) wavelength range was investigated by partially dehydrating the four main habits of gypsum (alabaster, satin spar, selenite, and massive) to form bassanite. Powdered samples of gypsum dehydrated at 100–115 °C and hand samples dehydrated at …
Gypsum: Oman is the world's largest gypsum exporter by weight, shipping approximately 8.74 million tons in 2021 primarily to ASEAN and South/East African countries, according to local press. Chromite: Approximately 30 million metric tons of chromite ore are in Oman, according to the Oman Chromite Company. Oman is …
In order to achieve the resourceful, large-scale and high-value utilization of bulk industrial solid wastes such as flue gas desulfurization gypsum (FGDG), fly ash (FA) and ground blast furnace …
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نشانی: شماره 1688، جاده شرقی گاوک، منطقه جدید پودونگ، شانگهای، چین.
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