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Learn about the properties, forms, and uses of calcium sulfate hemihydrate, also known as plaster of Paris, a material derived from gypsum. Find chapters and articles on its …
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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 MgSO4‐CaCl2‐H2O solution, which can transform into whitening short columnar α‐hemihydrate gypsum. The effects of aging …
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In the powder sample preparation processes (Fig. 3 (a)–(c)), the WGP was ground using a crusher to achieve a particle size comparable to that of α-CHG, ... In this study, recycled alpha-hemihydrate gypsum was manufactured from waste gypsum plasterboards based on the atmospheric pressure hydrothermal method. The univariate …
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In this study, phosphogypsum (PG) is simulated by doping fluorine and phosphorus ions in an analytically pure reagent of gypsum dihydrate. The influence of fluorine and phosphorus impurity and content on the dehydration reaction process of phosphogypsum and its crystalline micromorphology is assessed during the preparation …
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Study with Quizlet and memorize flashcards containing terms like Which of the following is true concerning the chemical properties of gypsum materials? a. Chemically, the mineral gypsum is a hemihydrate of calcium carbonate. b. To form the raw material into a powder, the manufacturer heats it and adds water. c. When the dihydrate is again mixed with …
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What is gypsum? What is hemihydrate gypsum? Define gypsum plaster and gypsum plasterboard. Where do gypsum deposits are located? List the different types of …
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The H 2 O released from gypsum altered one Ca position, which is the reason for the Ca located in two positions in the gypsum structure, although it maintains one position in the prepared HH-CSW structure. Download: Download high-res image (111KB) Download: Download full-size image; Fig. 10. HH-CSW atom-bond formation …
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hemihydrate gypsum, and the influence degree of different forms of soluble phosphorus is unclear. Therefore, the utilization of a-hemihydrate gypsum is greatly limited. In this study, the effect of soluble phosphorus on the setting time and mechanical properties of a-hemihydrate gypsum was investi-gated by adding different amounts of H 3PO 4 ...
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DOI: 10.1016/j.conbuildmat.2024.136656 Corpus ID: 269855858; Preparation of α-calcium sulfate hemihydrate with high mechanical strength from natural fibrous gypsum in KCl-mediated glycerol-water solution
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Grinding and calcining of gypsum with Pfeiffer grinding plants. 1 Two different modifi-cations of the hemihy-drate CaSO x 1⁄2. 4 H2O are produced. When gypsum is …
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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. Therefore, the dehydration process of gypsum and the rehydration of hemihydrate were investigated. This …
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Beta hemihydrate gypsum is suitable for construction applications where early high-strength development is necessary. Because alpha hemihydrate makes a denser, higher …
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1 Introduction . Calcium sulfate hemihydrate [CaCO 4 ∙ 0.5H 2 O(s)] can be found naturally in very dry climate regions in Egypt, Australia, Death valley and Kuwait as bassanite, but in the presence of water or humid atmosphere it can convert to dehydrate [1, 2]. Therefore, the production of hemihydrate industrially has been studied widely through the dehydration …
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Caopas is a gypsum mining company located in Baja California, México. Started operations in 1991, and is part of a mexican mining Group that also owns and operates Coal, Limestone, Manganese and Copper mines.
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For three experiments, gypsum fully converted to hemihydrate (Fig. 2c–h). Only the low-stress experiment at T = 129 °C retained ~1% of gypsum in the sample …
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In this study, the effect of sulphonated naphthalene formaldehyde condensate (SNF) and polycarboxylate (PC) superplasticizers on the performance of β-calcium sulphate hemihydrate plaster has been discussed. A considerable improvement in the properties of β-hemihydrate plaster was observed with an increase in …
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Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD) gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG-DSC), optical micrograph, X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometry …
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Download scientific diagram | Structures of a) gypsum, b) hemihydrate, and c) insoluble anhydrite with view in c-direction from publication: Crystallization and Phase Stability of CaSO4 and CaSO4 ...
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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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When gypsum is heated at about 150–160 °C, it loses approximately three-quarters of its water in a partial dehydration process and becomes hemihydrate gypsum (CaSO 4 •½H 2 O) or calcined gypsum; it is also known as beta gypsum (alpha gypsum is made by processing batches of gypsum under elevated pressure). Calcined gypsum or …
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Keywords: α-calcium sulfate hemihydrate, industrial by-product gypsum, FGD gypsum, phosphogypsum, preparation method 1. Introduction 1.1. α-calcium sulfate hemihydrate Calcium sulfate hemihydrate generally exists in two forms, i.e., α- and β-forms. As an important building material, the industrial production and application of β-form began ...
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DOI: 10.1016/j.jcrysgro.2021.126360 Corpus ID: 241731164; Preparation of hemihydrate gypsum with controllable morphology in Glycerol-NaCl-Water solutions with maleic acid @article{Chen2021PreparationOH, title={Preparation of hemihydrate gypsum with controllable morphology in Glycerol-NaCl-Water solutions with maleic acid}, …
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A readily monitored and controllable hydrothermal system for the facile, cost-effective transformation of FGD gypsum to calcium sulfate hemihydrate whiskers. Particuology (2021) H. Fu et al. Role and fate of the lead during the conversion of calcium sulfate dihydrate to α-hemihydrate whiskers in ethylene glycol-water solutions.
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Most modern gypsum processing is performed in machinery that combines the pulverization and calcining steps in the transformation of gypsum to hemihydrate. Equipment manufacturers such as Pfeiffer and Claudius-Peters specialize in this technology, known as "flash calcining."
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Here we report a facile and cost-effective wet-chemical approach to the synthesis of calcium sulfate hemihydrate nanowires (HH NWs, CaSO4·0.5H2O), and their robust performance in immobilizing water molecules to the crystal lattice of CaSO4 and then separating them from a surfactant-stabilized water-in-oil emulsion (mean droplet size of …
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In this work, α-hemihydrate gypsum (α-HH) microrods were synthesized in large scale using flue gas desulfurization (FGD) gypsum as the raw materials in alcohol-salt system under normal pressure. The … Expand. 4. Save. Crystallization Kinetics of α-Hemihydrate Gypsum Prepared by Hydrothermal Method in Atmospheric Salt Solution …
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The production of gypsum typically involves several steps, including mining, crushing, grinding, calcination, and drying. Here are the five steps in gypsum production: 1.
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Calcium sulfate occurs in nature in form of three different minerals distinguished by the degree of hydration: gypsum (CaSO4·2H2O), hemihydrate (CaSO4·0.5H2O) and anhydrite (CaSO4).
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thermal analysis in a sample of hemihydrate prepared by calcining gypsum under conditions simulating the manufacture of gypsum plaster in a kettle. By means of differential thermal analysis it is ...
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Learn how gypsum, hemihydrate and anhydrite react with water and change their crystal structure and solubility. See thermal analysis, dilatometry and …
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Alcohol–water solution-mediated transformation of gypsum into α-hemihydrate (α-HH) whiskers provides a green alternative for the high-value-added recycling of flue gas desulfurization (FGD) gypsum. … Expand. 5. PDF. Save. Effect of Soluble P2O5 Form on the Hydration and Hardening of Hemihydrate Phosphogypsum.
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Hemihydrate is a form of gypsum that is used as a binder in construction materials. Learn about the production methods, properties and applications of hemihydrate and its …
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Alpha high‐strength hemihydrate gypsum (CaSO 4 ·0.5H 2 O, α‐HH) with a large‐size columnar crystal (average size: 135.31 µm, maximum size: 500 µm) is successfully prepared via a NaCl ...
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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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Natural fibrous gypsum is a kind of high-quality gypsum resources, whose high-value added utilization pathway is to be transformed to α-calcium sulfate hemihydrate (α-HH), a cementitious material that can react with water to form pastes with mechanical strength.In this work, α-HH was prepared from natural fibrous gypsum in KCl mediated …
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