Utilization of phosphogypsum for the preparation of α‐calcium sulfate hemihydrate in chloride‐free solution under atmospheric pressure

Mi, Yang; Chen, Deyu; Wang, Shuzhou

doi:10.1002/jctb.5584

Cited by 23 publications

(17 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a cementitious material, the mechanical strength of α-HH is an important property of its market value, which depends on the crystal morphology [34]. Crystal modifier is a significant factor in controlling of α-HH crystals morphology.…”

Section: Effects Of Maleic Acid On the Morphology Of α-Hhmentioning

confidence: 99%

Facile preparation of high-strength α-CaSO4·0.5H2O regulated by maleic acid from phosphogypsum: experimental and molecular dynamics simulation studies

et al. 2020

View full text Add to dashboard Cite

Crystal modifier is a significant factor in preparation of α-hemihydrate gypsum (α-HH) from phosphogypsum (PG). The influence of maleic acid, reaction temperature, time, and solid-liquid ratio on the preparation of high-strength α-HH from PG was systematically studied herein. The optimum condition for α-HH prepared by hydrothermal autoclave method was pH of 4, temperature of 140 °C for 2.0 h with solid-liquid ratio of 4:5. Crystal modifier of maleic acid can effectively regulated the crystal morphology of α-HH. SEM-EDS and FTIR analysis suggested that maleic acid could preferentially absorbed on the top face of α-HH crystals that decreased the growth rate of α-HH along the c-axis, resulting in the morphology of α-HH crystals transformed to hexagonal prisms, and the regulatory mechanism was estimated by molecular dynamics (MD). When maleic acid (0.1%) was added, the obtained α-HH showed aspect ratio of 1.2, and the flexural and compressive strength of the hardened α-HH could reach to 14.79 and 46.24 MPa, respectively. All of these results will help to design long-term effectiveness of phosphogypsum recycling strategies.

show abstract

Section: Effects Of Maleic Acid On the Morphology Of α-Hhmentioning

confidence: 99%

Facile preparation of high-strength α-CaSO4·0.5H2O regulated by maleic acid from phosphogypsum: experimental and molecular dynamics simulation studies

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The equilibrium equation of gypsum solution can be described as:

. The solubility product constant can be expressed as:

, where a is activity, and n is equal to 0, 0.5, and 2, which represent anhydrite, hemihydrate and dihydrate, respectively [ 29 ]. The reaction of dihydrate to hemihydrate in supersaturated solution at high temperature is expressed as:

…”

Section: Resultsmentioning

confidence: 99%

Preparation of CSHW with Flue Gas Desulfurization Gypsum

Gao

et al. 2022

Materials

View full text Add to dashboard Cite

Calcium sulfate hemihydrate whiskers (CSHW), a multi-functional and high value-added building material, were prepared with flue gas desulfurization (FGD) gypsum by hydrothermal method, which could be a reasonable disposal of FGD gypsum. In order to obtain CSHW of a high aspect ratio, a series of manufacturing parameters such as reaction temperature, stirring speed, material–water ratio, and reaction time were investigated. The effect of stabilizing treatment and glycerol concentration on CSHW morphology were also studied by environmental scanning electron microscopy (ESEM) and statistical analysis. The results showed that the optimum preparing conditions of reaction temperature, stirring speed, water–material ratio, and reaction time were 160 °C, 200~300 rpm, 11:1 and 1 h, respectively. Furthermore, stabilizing treatment with octodecyl betaine was necessary for the preparation of CSHW. The final prepared whiskers had smooth surface, uniform morphology, a diameter of 260 nm, and a corresponding aspect ratio of 208.2. Moreover, the addition of glycerol reduced the activity of water, contributing to a lower reaction temperature and much smaller diameter.

show abstract

“…By adding an inorganic additive NaCl to the aqueous solution to make the solution supersaturated, DH dehydration yields α-HH. Then the organic additive succinic acid is added to transform it into short cylindrical α-HH with higher strength [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Crystallization Kinetics of α-Hemihydrate Gypsum Prepared by Hydrothermal Method in Atmospheric Salt Solution Medium

Wei

Zhang

2021

Crystals

View full text Add to dashboard Cite

α-Calcium sulfate hemihydrate (α-HH) is an important cementitious material, which can be prepared by hydrothermal method from calcium sulfate dihydrate (DH) in an electrolyte solution. Study of the conversion kinetics of DH to α-HH in NaCl solution is helpful for understanding the control process. In this paper, X-ray diffraction (XRD) patterns were applied to study the effect of temperature on the crystallization kinetics of α-HH to determine the kinetic parameters. The research results show that the sigmoidal shape of the α-HH crystallization curve follows the Avrami-Erofeev model, which describes the crystallization kinetics of α-HH formation. Applying Arrhenius law in experimental data and model calculations, an apparent activation energy of 124 kJ/mol for nucleation and an apparent activation energy of 810 kJ/mol for growth were obtained. By adjusting the temperature of the solution, the number of α-HH nucleation and growth steps increases, which can effectively increase the DH-α-HH conversion rate in the NaCI solution.

show abstract

Utilization of phosphogypsum for the preparation of α‐calcium sulfate hemihydrate in chloride‐free solution under atmospheric pressure

Cited by 23 publications

References 44 publications

Facile preparation of high-strength α-CaSO4·0.5H2O regulated by maleic acid from phosphogypsum: experimental and molecular dynamics simulation studies

Facile preparation of high-strength α-CaSO4·0.5H2O regulated by maleic acid from phosphogypsum: experimental and molecular dynamics simulation studies

Preparation of CSHW with Flue Gas Desulfurization Gypsum

Crystallization Kinetics of α-Hemihydrate Gypsum Prepared by Hydrothermal Method in Atmospheric Salt Solution Medium

Contact Info

Product

Resources

About