The hydration of calcium sulphate hemihydrate (CaSO 4 ·0.5H 2 O) leading to the crystallization of gypsum (calcium sulphate dihydrate – CaSO 4 ·2H 2 O) has been the subject of several investigations over a long period and a vast amount of data is widely distributed throughout in the literature. In this review article an overall picture of the …

What is gypsum? What is hemihydrate gypsum? Define gypsum plaster and gypsum plasterboard. Where do gypsum deposits are located? List the different …

Phosphogypsum (PG), as a waste by-product with high content and complicated impurities, is difficult to be utilised effectively. Herein, cleaner PG is prepared with "HCl H 2 SO 4 method", and thus is used to synthesise α-hemihydrate gypsum (α-HH) in CaCl 2 solution under atmospheric pressure. Morphology and mechanical …

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A sample of hemihydrate was prepared by heating 800 gm. of a washed natural gypsum for 5 hr. in a glass container filled to a depth of. 3 in. (oven temp. 170° C.). The sample was cooled and then ...

We use time-resolved cryogenic transmission electron microscopy (TR-cryo-TEM) on a supersaturated solution of calcium sulfate hemihydrate to examine the early stages of particle formation during the hydration of the hemihydrate. As hydration proceeds, we observe nanoscale amorphous clusters that evo …

It was apparent that the conversion of hemihydrate to gypsum was postponed and decreased at pH 11.08. The hydration degree was 2.03% after 2 h hydration and only came up to 41.28% after 1 d hydration, and decreased by 26.66% compared with the reference sample, which can be one of the reasons for the reduction in strength.

β- Hemihydrate (also known as plaster of Paris) is the most commonly used gypsum binder in construction. It is produced in an apparatus connected to air. Different …

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QXRD results show the transformation of gypsum into hemihydrate after a residence time of 8 h and 4 h. SEM images distinguish the α‐HH and β‐HH modifications. For fgd‐gypsum pellets, the ...

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 …

Hemihydrate gypsum (β-CaSO 4 •1/2H 2 O, purity>97.0%) was obtained from Acros Organics, Germany, and its particle size distribution and morphology are shown in Fig. 1.Its mean particle size (d50) was 9.803 µm, and the scanning electron microscopy (SEM) images showed that β-CaSO 4 •1/2H 2 O exhibited irregular particles with cracks …

Alpha hemihydrate is a form of calcium sulfate hemihydrate with a dense crystal structure known for its rapid setting time and high setting expansion in gypsum products. Beta hemihydrate, on the other hand, is a form of calcium sulfate hemihydrate with a more open crystal structure, often used in specialized applications.

Flue gas gypsum may be converted to α-hemihydrate by suspending the starting material in inorganic salt solutions of high concentration or in diluted sulfuric acid and maintaining the suspension at boiling, or near boiling temperature for a period of time. The crystal morphology of the produced α-hemihydrate gypsum and, thus, its quality ...

This study combined inorganic α-hemihydrate gypsum (α-HHG) with organic polyacrylamide (PAM) hydrogel to create a novel α-HHG/PAM composite material. Through this facile composite strategy, this fabricated material exhibited a significantly longer initial setting time and higher mechanical strength compared to α-HHG. The …

Then through the secondary gypsum crushing, such as impact crusher, cone crusher,etc. the mineral is crushed to less than 2cm. The end products will be transported to calcining kiln through bucket elevator. We can chanage the temperature of the calcining kiln to produce β-type hemihydrate gypsum, anhydrite and over gypsum. Services.

Spin-coated cellulose thin films have been used as model substrates to investigate the crystallization of calcium sulfate dihydrate (gypsum) under industrially relevant conditions using highly concentrated dispersions of calcium sulfate hemihydrate (bassanite).Pre-treatment of the films by regeneration in aqueous solutions of Ca 2+ promotes gypsum …

To produce plasters or wallboard, gypsum must be partially dehydrated or calcined to produce calcium sulfate hemihydrate (CaSO4 1⁄2H 2O), commonly called stucco. A …

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.

Hemihydrate occurs in two formations of α- and β-type. Among them β-hemihydrate is mainly used to produce gypsum plasterboard since the hydration product of the α …

study provides a concise and efficient approach to the modification research of hemihydrate gypsum. Keywords: gypsum–polymer composite; …

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 gypsum.To obtain α-CSH with the satisfactory performances, a facile hydrothermal-aging pretreatment process for FGD gypsum raw materials was proposed, where FGD …

Furthermore, a commercial α-hemihydrate gypsum (α-CHG) was included in this study for comparative analysis with the α-RHG prepared from WGP. Overall, this study aimed to achieve three primary objectives. ... In the powder sample preparation processes (Fig. 3 (a)–(c)), the WGP was ground using a crusher to achieve a particle size …

Gypsum-based binders are generally based on the reaction between calcium sulfate hemihydrate (HH) and water to form calcium sulfate dihydrate (DH). Often gypsum can be used as a raw material to obtain hemihydrate. In this study, the obtained alpha hemihydrate consists of large crystals that have more or less lattice defects according …

In this study, a high-value-added recycled α-hemihydrate gypsum (α-RHG) generated from WGP using the atmospheric pressure hydrothermal method (APHM) was utilized to manufacture a 3D printed material.

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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The controlled synthesis of α-hemihydrate (α-HH) gypsum using flue gas desulfurized gypsum is essential for the utilization of calcium and sulfur resources. An aspect ratio (AR) close to 1 is essential to improve the quality and performance of α-HH gypsum. To solve this problem, the morphological modification of α-HH gypsum by …

BKG Business Group. Established in 2000 under the patronage of NSP group, BKG is the Thailand's leading corporate who specializes in Gypsum, Calcium Sulfate, and Calcium Carbonate semi-raw materials and finish goods in the field of construction, agriculture, and chemical industries. With our focus on science and engineering innovation, we are ...

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 …