Effect of maleic acid and pH on the preparation of α-calcium sulfate hemihydrate from phosphogypsum in Mg(NO3)2 solution

Li, Zirui; Liu, Yong; Xing, Dongxian; Hua, Quanxian; Wang, Baoming; Liu, Li; Tang, Jianwei

doi:10.1007/s10163-021-01304-6

Cited by 9 publications

(10 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This indicates that MA inhibits the dehydration process. This inhibitory effect was also observed by Li et al [14], who concluded that MA ionizes the carboxyl group in water which then forms a coordination compound with Ca 2+ that adsorbs on α-HH surface.…”

Section: Effect Of Maleic Acidsupporting

confidence: 75%

α‐calcium sulfate hemihydrate formation using natural anhydrite as raw material

Eicheler,

Heisig,

Hilbig

et al. 2023

ce papers

View full text Add to dashboard Cite

This study investigates the potential of α‐HH formation from gypsum originating from activated and hydrated natural anhydrite. For this, gypsum was prepared from natural anhydrite and treated in an autoclave process under hydrothermal conditions (150 mbar and 130 °C). For comparison, fgd‐gypsum was treated accordingly. Succinic acid, maleic acid and additional α‐HH seeds were used as crystallization aids. 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 β‐HH modification predominates. Gypsum from natural anhydrite shows α‐HH crystals with succinic acid and without crystallization aid. When maleic acid is present, crystals appear as intermediates between α‐HH and β‐HH. To isolate the effect of the crystallization aids, α‐HH and succinic acid were used separately and simultaneously. SEM images indicate the formation of α‐HH from β‐HH. The shapes of the original β‐HH conglomerates are still visible, yet acicular crystals with smooth surfaces (α‐HH) are visible at a high magnification. Longest crystals appear when α‐HH and succinic acid are used simultaneously indicating a synergetic effect of both crystallization aids.

show abstract

Section: Effect Of Maleic Acidsupporting

confidence: 75%

α‐calcium sulfate hemihydrate formation using natural anhydrite as raw material

Eicheler,

Heisig,

Hilbig

et al. 2023

ce papers

View full text Add to dashboard Cite

show abstract

“…The soluble P 2 O 5 impurities in phosphogypsum mainly come from residual phosphoric acid (H 3 PO 4 ), which mainly exists in the form of H 3 PO 4 , H 2 PO 4 − and HPO 4 2− [23,24]. The greatest harm of soluble P 2 O 5 impurities is that it can cause the pH of the reaction liquid system to change when phosphogypsum is used to prepare α-HH, which will inevitably affect the crystallization habit of α-HH and ultimately affect the physical and mechanical properties of the product [25,26]. To avoid the harm of impurities, most current practices include the pre-purification of phosphogypsum before it is used in the production of α-HH, which significantly increases the utilization cost of phosphogypsum and is not conducive to its high-value utilization.…”

Section: Introductionmentioning

confidence: 99%

Effect of Phosphoric Acid on the Preparation of α-Hemihydrate Gypsum Using Hydrothermal Method

Zhang,

Wang,

Hou

et al. 2023

Materials

View full text Add to dashboard Cite

The effects of phosphoric acid (H3PO4) in pressurized aqueous solution on the dehydration of CaSO4·2H2O to form α-hemihydrate gypsum (α-HH) phase and the regulation of crystal shape were studied in this paper in order to provide guidance for the low-cost and high-value utilization of phosphogypsum. The results showed that H3PO4 can significantly accelerate the formation rate of the α-HH phase and that it did not participate in the formation of the α-HH phase in the form of eutectic phosphorus during crystalline phase transformation. In terms of crystal shape regulation, H3PO4 can impact the effect of a citric acid crystal regulator on α-HH crystal shape regulation. The more H3PO4 added, the greater the aspect ratio of α-HH. Accordingly, the water consumption and 2 h dry compressive strength of α-HH products were gradually increased and decreased with an increase in H3PO4 content, respectively. Despite this, the compressive strength of α-HH can still meet the requirements of the α20 grade in JC/T 2038-2010 “α High Strength Gypsum” in China when the H3PO4 content was limited to less than 0.4%.

show abstract

“…The dihydrate phosphogypsum formed during the hydration process should be larger and uniform for a higher filtration strength. ,− The phosphogypsum produced in wet process phosphoric acid is usually needle-like with a large aspect ratio, − which is not conducive to the filtering process for that the phosphogypsum with a lower aspect ratio benefits the filtration process …”

Section: Introductionmentioning

confidence: 99%

Revealing Mechanism of Hemihydrate–Dihydrate Phosphogypsum Transformation and Minimizing Phosphorus Loss in Wet Process Phosphoric Acid

Huo,

Guo,

Liu

et al. 2023

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Effect of maleic acid and pH on the preparation of α-calcium sulfate hemihydrate from phosphogypsum in Mg(NO3)2 solution

Cited by 9 publications

References 48 publications

α‐calcium sulfate hemihydrate formation using natural anhydrite as raw material

α‐calcium sulfate hemihydrate formation using natural anhydrite as raw material

Effect of Phosphoric Acid on the Preparation of α-Hemihydrate Gypsum Using Hydrothermal Method

Revealing Mechanism of Hemihydrate–Dihydrate Phosphogypsum Transformation and Minimizing Phosphorus Loss in Wet Process Phosphoric Acid

Contact Info

Product

Resources

About