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Dry grinding of gypsum (CaSO4·2H2O) with hydrated minerals, such as talc, kaolinite or montmorillonite as an additive was conducted in a planetary ball mill in order to …
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The main dehydration of the calcium sulphate dehydrate part of synthetic gypsum occurs between 95 and 170 (heating rate 5 min-') and seems to proceed via a process with an …
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In this introduction, we'll explore the definition and composition of gypsum. Gips – Lubin, Poland Original image of the Gypsum crystal. You can see luminescence of the crystal in the next photo. Gypsum, Red River Floodway, …
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Gypsum (calcium sulfate dihydrate) is one of the most used inorganic binding materials in the world. During calcination, calcium sulfate subhydrates are formed and, for technical reasons, are ...
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Calcined plaster reacts with water to become dihydrate gypsum, causing its crystals to interlock and solidify. CaSO 4 ･1/2H 2 O+3/2H 2 O→CaSO 4 ･2H 2 O. The amount of water (ml, cc, …
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Increased inter-ionic distance also decreases density, so gypsum's specific gravity is only 2.32, while that of anhydrite is substantially higher at 2.97. Water of hydration also …
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Gypsum (calcium sulfate dihydrate) is one of the most used inorganic binding materials in the world. During calcination, calcium sulfate subhydrates are formed and, for technical reasons, are mixed with water to …
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Gypsum powder works by undergoing a chemical reaction with water, transforming from a dry powder into a solid, rigid material. Understanding Gypsum and Its Tran. ... (often …
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The synthesis of α-calcium sulfate hemihydrate (α-CSH) from flue gas desulfurization (FGD) gypsum is a good way to realize the comprehensive utilization of FGD …
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During this process, the hydroxyl bond in gypsum is weakened, and thus leads to the dehydration of gypsum into hemihydrate. Thus, the sample is required to heat in an oven …
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The dissolution of hemihydrate and growth of gypsum is a two-step process: at first, gypsum seeds appear in the saturated solution with no significant dissolution of hemihydrate grains (1-2 ...
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The dehydration process proceeds stepwise and leads to metastable calcium sulfate phases. Bassanite (calcium sulfate hemihydrate, CaSO 4 ·0.5 H 2 O) is formed at the loss of …
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According to the process, a high-purity modified dihydrate gypsum consisting of large crystals, which cannot be generally obtained, can be produced by converting raw …
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The gypsum-anhydrite transformation in aqueous solutions, on the other hand, can occur through two different mechanisms depending on temperature (Azimi and Papangelakis, …
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What is Gypsum? DATE: 16-07-2007 I. Natural Gypsum A. Introduction The mineral Gypsum precipitated some 100 to 200 million years ago when sea water evaporated. From a chemical …
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The transformation of gypsum into anhydrite at low temperatures under atmospheric pressure as well as at elevated temperatures (150 °C and 200 °C) inside an autoclave was …
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As the results, it was found that the dihydrate gypsum is changed into the hemihydrate gypsum under thermal condition of 90 A degrees C and the hemihydrate gypsum …
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The deterioration of buildings and monuments by gypsum is the result of crystallization cycles of this salt. Although gypsum can dehydrate to a hemihydrate, the …
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One way is to heat up dihydrate in a rotary kiln or a vertical digester. The rotary kiln is a continuous process which is often used; the vertical digester is another common …
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consumption of hemihydrate and formation of dihydrate. 1. Ultrasonic results indicate gypsum hydration reaction consists of two stages: the dissolution of hemihydrate in the first stage and …
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In the high-temperature and low water vapor pressure region, gypsum dehydrates to form γ-CaSO 4 in a single-step process (CaSO 4 ·2H 2 O → γ-CaSO 4); with increasing water vapor …
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Plaster, made of calcium sulfate hemihydrate (CaSO 4 •½H 2 O) and/or γ-anhydrite (CaSO 4) is obtained by dehydration of gypsum (CaSO 4 ·2H 2 O) at 100–200 °C. When …
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During grinding in an unventilated and unheated laboratory mill for 30 min, 20% gypsum dehydrated to hemihydrate. If the grinding temperature in some mills is increased to 90°C, …
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The partially dehydrated mineral is called calcium sulfate hemihydrate or calcined gypsum (commonly known as plaster of Paris) (CaSO 4 ·nH 2 O), where n is in the range 0.5 to 0.8. …
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Comparison of the data selection of Shen et al. (2019) and in this work for gypsum. Black stars: accepted data of this work (top); red circles (open and closed) accepted by Shen …
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Calcium sulphate hemihydrate commonly known as plaster of Paris is extensively used in buildings, ceramics and medical industries. Hydration of hemihydrate is a highly …
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gypsum is stable in the low-temperature and high water vapor pressure region and does not dehydrate to form any calcium sulfate hemihydrate. Finally, the rehydration mechanism of soluble
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Hydration behavior []. The system CaSO 4 –H 2 O: Calcium sulfate can appear in three different hydrate phases: Anhydrite (CaSO 4)- the above mentioned anhydrous form.; Bassanite …
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dehydration still needs further investigation, especially the behaviour of the β-hemihydrate and gypsum produced from it is still poorly understood. This article focuses on the role of water on …
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The group reported that gypsum actually forms in a three-step process: precipitation of nanocrystals of bassanite — or calcium sulfate hemihydrate, with one water molecule for …
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