Gypsum, scientifically known as Calcium Sulfate Dihydrate (CaSO 4 ·2H 2 O), is a naturally occurring mineral primarily formed from the evaporation of ancient bodies of sea water …
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Gypsum is an evaporite mineral most commonly found in layered sedimentary deposits in association with halite, anhydrite, sulfur, calcite, and dolomite. Gypsum (CaSO 4. 2H 2 …
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— Flue-gas desulphurization (FGD) gypsum is a highly prevalent industrial by-product worldwide, which can be an excellent alternative to natural gypsum due to its high content of CaSO4·2H2O. The preparation of α-calcium sulfate hemihydrate is a high-value pathway for the efficient use of FGD gypsum. Here, a dynamic method, or an improved …
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This work reports a facile sodium cation (Na+)-mediated approach to synthesize α-calcium sulfate hemihydrate (α-HH) whiskers, with calcium sulfate dihydrate (DH) as the precursor, in ethylene glycol (EG)–water solutions at 95.0 °C and atmospheric pressure. The as-synthesized α-HH whiskers exhibit a width of 3–5 μm and a length of 600–700 μm, …
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Gypsum was known in Old English as spærstān, "spear stone", referring to its crystalline projections.(Thus, the word spar in mineralogy is by way of comparison to gypsum, referring to any non-ore mineral or crystal that forms in spearlike projections). In the mid-18th century, the German clergyman and agriculturalist Johann Friderich Mayer investigated …
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— Long whiskers of dihydrate are visible beside some smaller, star-like gypsum crystals with many branches. The created structures were also studied with ESEM after drying; most of the water was removed …
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— The gypsum dihydrate seed crystal was synthesized by reaction of CaCl 2, Na 2 SO 4 and sodium citrate (Na 3 C 6 H 5 O 7) in aqueous solution. All reagents were prime classes from Kanto Kagaku Co., Inc. 2.2. ExperimentalSynthesis of large plate-like gypsum dihydrate from waste gypsum board was as follows.
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— Using FGD gypsum as the raw material, whitening and large prismatic dihydrate gypsum can be obtained by dissolution-crystallization and decoloring process with α-hemihydrate gypsum whiskers prepared in MgSO 4-CaCl 2-H 2 O solution, which can transform into whitening short columnar α-hemihydrate gypsum. The effects of aging …
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— can be summarized into two main categories: the dihydrate process (x = 2, gypsum as the final crystal form) and the nondihydrate process (also known as the hemihydrate process because hemihydrate is involved, although it is not necessarily the final crystal form). The dihydrate process is the earliest
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— Calcium sulfate exists in three forms, namely dihydrate or gypsum (CaSO4·2H2O), anhydrite (CaSO4), and hemihydrate or bassanite (CaSO4·0.5H2O) depending on temperature, pressure, pH, and formation conditions. The formation of calcium sulfates occurs widely in nature and in many engineering settings. Herein, a …
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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 form dihydrate again. ... Gypsum crystal, reaction stopped after beginning of dehydration, OM. Crystals 2022, 12, 1780 6 of 14 3.2 ...
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— The presence of impurities from raw materials directly affects the crystal shape control, process, and product performance of high-strength α-hemihydrate gypsum (α-HH,α-CaSO 4 •0.5H 2 O) from industrial by-product phosphogypsum (PG). In this work, effect of sodium fluoride on the crystal regulation of high-strength α-HH using calcium …
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— The calcium sulphate dihydrate gypsum (CaSO 4 ·2H 2 O) is the most common sulphate evaporite mineral on our planet 1.Sulphate evaporites play an important role in Earth's sulphur cycle and are ...
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Gypsum occurs in extensive beds associated with other evaporite minerals (e.g., anhydrite and halite), particularly in Permian and Triassic sedimentary formations; it is deposited from ocean brine, followed by anhydrite and halite.It also occurs in considerable quantity in saline lakes and salt pans and is an important constituent of cap rock, an anhydrite-gypsum …
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— Alabaster, a form of gypsum. Credit: Wikimedia Commons. Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate (CaSO4·2H2O). It is renowned for its wide use in the manufacturing ...
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Ground gypsum in and by itself will not get hard when mixed with water. Gypsum has to be converted to a "hemihydrate" by first cooking it. The process of cooking gypsum is called "calcination." As previously mentioned, two molecules of water are part of the gypsum (dihydrate) crystal.
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— Effects of citric acid on crystalline habit and crystal morphology of gypsum dihydrate were analyzed in great detail. The retarding mechanism of citric acid was also discussed from the standpoint ...
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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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Gypsum, a naturally occurring mineral with the chemical formula CaSO4·2H2O, exhibits several important chemical properties that contribute to its versatility and usefulness in various applications. Here are some key chemical properties of gypsum: 1. Hydrated Structure:Gypsum is a hydrated …
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— the volume shrinkage of the gypsum material occurs at the early stage of solidification. When the mixture of a model material is rigid, the expansion in all directions will affect the size of the model [11,12]. On the one hand, the gypsum material will form calcium sulfate dihydrate crystal during hydration with continuous growth and re ...
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— 1. Introduction1.1. General context. Gypsum plaster is an inorganic binder that is prepared in a two-step process. The first step is dehydration: heated to 100–200 °C, gypsum (CaSO 4 ·2H 2 O) releases water as vapor [1, 2] and, depending on temperature and water vapor partial pressure (p H2O) [3, 4] forms either hemihydrate (CaSO 4 •½H 2 …
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The crystal morphology of the created dihydrate is a mixture of dove-tailed twins (yellow circle) and more (blue circle) or less branched crystal needles; there are also crystal …
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— The axial development of calcium sulfate dihydrate (gypsum) scaling on selected reverse osmosis (RO) membrane surfaces was investigated experimentally in a plate-and-frame RO system. Scaling experiments with model solutions demonstrated progressive axial development of surface gypsum crystals along the membrane surface. …
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Most of the time, it's clear, white, silver, or brown. The crystal has a smooth feel, like satin or chalk. Flattened blades or prismatic shapes are the most recognizable shapes in Gypsum crystals. Crystal collectors like how delicate and complicated this material looks. Calcium sulfate dihydrate is found in Gypsum.
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Gypsum, common sulfate mineral of great commercial importance, composed of hydrated calcium sulfate. It occurs in extensive beds associated with other evaporite minerals, particularly in Permian and …
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— In addition, the negative effect of the high adsorption amount on the crystal precipitation of calcium sulfate dihydrate is considered to be an important reason for retarding effect. View Show ...
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— The results indicate that STPP changes the crystal growth habit of gypsum dihydrate, leading to large crystal size and transformation of the crystal shape from needle-like to short prismatic or ...
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Characteristics & Properties of Gypsum. Composition: Calcium sulfate dihydrate (CaSO₄·2H₂O). This means gypsum is a hydrated sulfate mineral, containing calcium, sulfur, and chemically bound water molecules. ...
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— The beta form denotes a specific crystal structure, distinguishing it from the alpha form of calcium sulfate hemihydrate. ... where it reacts with water to form calcium sulfate dihydrate, also known as gypsum, resulting in a hardened solid material. 2. What is the difference between calcium sulphate dihydrate and hemihydrate?
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— Since gypsum is dissolved in the water over a period of time, only on rare occasions it can be found in the form of sand, and hence mostly it is found in the crystal form. The gypsum crystal of more than 3 metres or of almost 10 feet in length, and of 0.4 metres or almost about 1.5 feet in diameter, was found in the Braden mine of Chile.
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Calcium sulphate dihydrate (CaSO4·2H2O or gypsum) is used widely as building material because of its excellent fire resistance, aesthetics, and low price. Hemihydrate occurs in …
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