Effect of Mg2+, Al3+, and Fe3+ ions on crystallization of type α hemi-hydrated calcium sulfate under simulated conditions of hemi-hydrate process of phosphoric acid

Yang, Lin; Cao, Jian; Luo, Tong

doi:10.1016/j.jcrysgro.2018.01.014

Cited by 27 publications

(13 citation statements)

References 15 publications

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“…The peaks observed at 14.72°, 25.67°, and 29.69° were assigned as the specific peaks of CSH. This result was in accordance with the literature , . As demonstrated in Fig.…”

Section: Resultsmentioning

confidence: 99%

Ultrasonic Irradiation during the Calcium Sulfate Hemihydrate to Dihydrate Transformation Process

Polat

2019

Chem Eng & Technol

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The ultrasound-assisted transformation of calcium sulfate hemihydrate (CSH) to calcium sulfate dihydrate (CSD) was studied using three ultrasonic power settings. In addition to continuously measuring the variation in the conductivity value with time, the process was followed by X-ray diffraction and scanning electron microscopy (SEM) analysis. Thermogravimetric analysis, Fourier transform infrared, mass spectrometry, and filtration analyses helped to determine the physicochemical properties of the as-obtained crystals. The morphological changes in the surface morphology were observed by SEM. The experimental results indicate that ultrasonic irradiation and its intensity have a significant effect on the crystal size, morphology, adsorption, and filtration characteristics. Mandelic acid in combination with ultrasonic irradiation can be used as an accelerator for the transformation process from CSH to CSD.

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“…The peaks observed at 14.72°, 25.67°, and 29.69° were assigned as the specific peaks of CSH. This result was in accordance with the literature , . As demonstrated in Fig.…”

Section: Resultsmentioning

confidence: 99%

Ultrasonic Irradiation during the Calcium Sulfate Hemihydrate to Dihydrate Transformation Process

Polat

2019

Chem Eng & Technol

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“…This attraction reduces the collision probability of Ca 2+ and SO 4 2– ions and thus affects the crystal growth rate. 37 Meanwhile, the adsorption of ions is proved as another reason to lead to the inhibition of crystal growth. 38 With the increase of Al and Fe concentrations, the nucleation rate and agglomeration kernel first increased and then decreased.…”

Section: Results and Discussionmentioning

confidence: 99%

Effects of Impurities on CaSO₄ Crystallization in the Ca(H₂PO₄)₂–H₂SO₄–H₃PO₄–H₂O System

Zhu

Xu³

et al. 2019

ACS Omega

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Wet-process phosphoric acid is a fundamental process in the fertilizer industry. The influence of impurities on crystallization kinetics of CaSO 4 was investigated in the Ca(H 2 PO 4 ) 2 –H 2 SO 4 –H 3 PO 4 –H 2 O system using a mixed suspension mixed product removal crystallizer. Effects of Si, Al, Fe, Mg, K, and Na on crystal morphology and structure were examined in the highly acidic system through scanning electron microscopy and high-resolution transmission electron microscopy. Results show that the increase of Mg, K, and Na content facilitates crystal growth. Si, Al, and Fe are beneficial to CaSO 4 crystal growth at a certain concentration range. Impurities also affect the crystal morphology, and the addition of Si, Fe, and Na promotes the formation of needle-like crystals compared with other impurities. X-ray diffraction results show that the preferred crystal growth direction is (020), and the interplanar spacing of the crystals is affected by the element radius of the impurities.

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“…In the preparation of α-HH from phosphogypsum, the hemihydrate gypsum usually has a long columnar shape and incomplete crystals due to its growth characteristics, so it is necessary to add a crystal transfer agent to assist crystal growth during the conversion process to obtain more dense and regular crystals. Yang et al used Mg 2+ , Al 3+ , and Fe 2+ ions as transcrystallizing agents to study their effects on α-HH crystallization, and the results showed that transcrystallizing agents accelerated the crystallization rate of gypsum crystals, increased the crystal surface energy, critical nucleation radius, and transformed α-HH crystals from long columnar to short columnar crystals 33 . Therefore, using PG as raw material and adding transcrystallizer to assist crystallization to prepare α-HH not only realizes resource recycling, but also protects natural gypsum resources and realizes sustainable development of environment, economy and society.…”

Section: Introductionmentioning

confidence: 99%

The study on the effect of flotation purification on the performance of α-hemihydrate gypsum prepared from phosphogypsum

Wang

Dong

et al. 2022

Sci Rep

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Phosphogypsum (PG) is a massive industrial solid waste. In this paper, PG was purified by flotation method, and α-hemihydrate gypsum (α-HH) was prepared by the autoclaving method. The morphology of α-HH was adjusted by adding different doses of Maleic acid and Aluminium sulfate. The results showed that after flotation purification, the impurity content in PG was significantly reduced, the soluble phosphorus content decreased from 0.48 to 0.07%, the PG purity increased from 73.12 to 94.37%, and the PG whiteness risen from 19.4 to 40.5. Then the performance of α-HH prepared from PG before and after purification was compared. Fixing the amount of aluminium sulfate at 0.2 wt%, the reaction temperature at 140 °C, and the reaction time at 120 min, the average length/diameter ratio of α-HH crystals decreased from 7.2 to 0.6 as the amount of Maleic acid increased from 0 to 0.17 wt%. When the amount of Maleic acid was 0.13 wt%, the α-hemihydrate gypsum reached the best mechanical properties. The mechanical strength of high strength gypsum prepared from PG concentrate was significantly better than that of raw PG, indicating that flotation purification can effectively improve the performance of PG. In this study, a new method of PG purification and resource utilization was proposed.

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Effect of Mg2+, Al3+, and Fe3+ ions on crystallization of type α hemi-hydrated calcium sulfate under simulated conditions of hemi-hydrate process of phosphoric acid

Cited by 27 publications

References 15 publications

Ultrasonic Irradiation during the Calcium Sulfate Hemihydrate to Dihydrate Transformation Process

Ultrasonic Irradiation during the Calcium Sulfate Hemihydrate to Dihydrate Transformation Process

Effects of Impurities on CaSO₄ Crystallization in the Ca(H₂PO₄)₂–H₂SO₄–H₃PO₄–H₂O System

The study on the effect of flotation purification on the performance of α-hemihydrate gypsum prepared from phosphogypsum

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Effect of Mg2+, Al3+, and Fe3+ ions on crystallization of type α hemi-hydrated calcium sulfate under simulated conditions of hemi-hydrate process of phosphoric acid

Cited by 27 publications

References 15 publications

Ultrasonic Irradiation during the Calcium Sulfate Hemihydrate to Dihydrate Transformation Process

Ultrasonic Irradiation during the Calcium Sulfate Hemihydrate to Dihydrate Transformation Process

Effects of Impurities on CaSO4 Crystallization in the Ca(H2PO4)2–H2SO4–H3PO4–H2O System

The study on the effect of flotation purification on the performance of α-hemihydrate gypsum prepared from phosphogypsum

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Effects of Impurities on CaSO₄ Crystallization in the Ca(H₂PO₄)₂–H₂SO₄–H₃PO₄–H₂O System