Recycling utilization of phosphogypsum in eco excess-sulphate cement: Synergistic effects of metakaolin and slag additives on hydration, strength and microstructure

Wang, Ziyan; Shui, Zhonghe; Sun, Tao; Li, Xiaosheng; Zhang, Mingzhong

doi:10.1016/j.jclepro.2022.131901

Cited by 52 publications

(7 citation statements)

References 80 publications

(95 reference statements)

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“…FTIR spectroscopy can be used as a supplement to XRD to characterize the binding properties of the crystalline and amorphous phases of a substance. It was also used to determine the chemical concentration and gel polymerization through the strength and breadth of the absorption bands [ 30 ]. Figure 8 depicts the FTIR results of the three samples (RS-0, RS-25, and RS-60) after 28 days of curing.…”

Section: Resultsmentioning

confidence: 99%

“…The high-frequency (4000–1600 cm −1 ) spectral bands of PG were related to the asymmetric and symmetric stretching vibrations of the O-H bond in water [ 30 ]. The vibrational absorption bands of the S-O bond were observed at 1115 cm −1 , 668 cm −1 , and 601 cm −1 , and the 468 cm −1 bending vibrations of SiO 4 were associated with the quartz in PG [ 30 ]. In addition, the band at 839 cm −1 was associated with the eutectic phosphorus in PG [ 31 ].…”

Section: Methodsmentioning

confidence: 99%

“…In addition, the band at 839 cm −1 was associated with the eutectic phosphorus in PG [ 31 ]. For RS, the asymmetric stretching band of -Si-O-H was observed at 3424 cm −1 [ 30 ]. Furthermore, the Si-O stretching band at 1084 cm −1 was associated with feldspar, whereas the Si-O vibrational band at 1035 cm −1 was associated with quartz [ 5 ].…”

Section: Methodsmentioning

confidence: 99%

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Preparation and Micromechanics of Red Sandstone–Phosphogypsum–Cement Composite Cementitious Materials

Kong,

Zhou,

Guo

et al. 2023

Materials

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Based on the physical and chemical properties of red sandstone (RS), RS is used to produce composite cementitious materials. The flowability, mechanical strength, and micromechanics of a red sandstone–cement binary cementitious material (RS-OPC) were investigated as functions of the amount of RS replacing the cement (OPC). Additionally, the feasibility of producing red sandstone–phosphogypsum–cement composite materials (RS-PG-OPC) using the phosphogypsum (PG)- enhanced volcanic ash activity of RS was investigated. The products of hydration and microstructures of RS-OPC and RS-PG-OPC were analyzed by XRD, FTIR, TG-DTG, and SEM. RS enhanced the flowability of RS-OPC relative to the unmodified cement slurry but lowered its mechanical strength, according to the experiments. When the quantity of OPC replaced was greater than 25%, the compressive strength after 28 days was substantially reduced, with a maximum reduction of 78.8% (RS-60). The microscopic mechanism of RS-OPC suggested that the active SiO2 in the RS can react with Ca(OH)2 to produce C-S-H but can only utilize small quantities of Ca(OH)2, confirming the low volcanic ash activity of RS. RS was responsible for dilution and filling. The incorporation of 5% PG into RS-PG-OPC slowed the hydration process compared with RS-OPC without PG but also increased the flowability and aided in the later development of the mechanical strength. This was primarily because the addition of PG provided the system with sufficient Ca2+ and SO42− to react with [Al(OH)6]3− to form ettringite (AFt), therefore accelerating the dissolution of Al3+ in RS to generate more AFt and C-(A)-S-H gels. To some extent, this excites the volcanic ash of RS. Therefore, if there is an abundance of waste RS in the region and a lack of other auxiliary cementitious materials, a sufficient quantity of PG and a finely powdered waste RS component can be used to replace cementitious materials prepared with OPC to reduce the mining of raw OPC materials.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Preparation and Micromechanics of Red Sandstone–Phosphogypsum–Cement Composite Cementitious Materials

Kong,

Zhou,

Guo

et al. 2023

Materials

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“…A polycarboxylic ether-based superplasticizer (SP) was used to adjust the workability. The SP had a solid content of about 20% and a water-reducing rate of more than 30% [ 20 , 21 ].…”

Section: Methodsmentioning

confidence: 99%

Effect of Vibration Procedure on Particle Distribution of Cement Paste

et al. 2023

Self Cite

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Vibration procedures significantly affect the performances of cement-based materials. However, studies on the distribution of certain particles within cement-based materials are limited due to the complexity and difficulty of identifying each specific particle. This paper presents a new method for simulating and quantifying the movements of particles within cement paste through the use of “tagged materials”. By separating the tagged particles from the cement paste after vibration, the distribution of the particles in the cement paste can be calculated statistically. The effect of the vibration time and frequency, fresh behavior, and powder characteristics of cement paste on particle motions are investigated. The results demonstrate that when the vibration exceeds 1800 s, it induces a significant uneven dispersion of microparticles. This effect is more pronounced at low viscosities (<1 Pa·s) of cement paste or high vibration frequencies (>200 Hz). Larger and denser particles exhibit greater dispersion. This method provides a valuable tool for investigating the theory of particle motion in cement paste, which is crucial for understanding the influence of vibration on the properties of cement-based materials.

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“…The biggest challenge in the sulfuric acid process is the generation of phosphogypsum . Phosphogypsum consists of CaSO 4 , impurities (iron, aluminum, and magnesium), phosphate precipitation, acid-insoluble matter, soluble phosphorus, and so on. − These impurities are mixed with CaSO 4 , limiting the utilization of phosphogypsum. − Generally, to produce 1 ton of phosphoric acid, approximately 4–5 tons of phosphogypsum are produced in the traditional sulfuric acid process . The annual output of phosphogypsum is approximately 2.8 × 10 8 tons in the world. , Large amounts of phosphogypsum cause a serious waste of resources and environmental pollution. , Ca 5 F false( PO 4 false) 3 + 5 H 2 SO 4 + n H 2 O → 3 H 3 PO 4 + 5 CaS O 4 · n H 2 O ↓ + HF …”

Section: Introductionmentioning

confidence: 99%

Study on Controlling the Dissolution of Calcium Dihydrogen Phosphate Using Ternary Phase Diagrams to Improve the Production Process of Phosphoric Acid

Chen

Zheng

Tang

et al. 2022

Ind. Eng. Chem. Res.

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Phosphogypsum is a solid byproduct in the production of phosphoric acid in the traditional sulfuric acid process, and its output has caused a huge economic and environmental burden. In order to avoid the production of phosphogypsum and efficiently produce phosphoric acid, a novel study on the decomposition of phosphate ore by phosphoric acid was carried out. The influence of parameters on the decomposition efficiency of phosphate ore were explored systemically using response surface methodology (RSM). The concentration of phosphoric acid was the most important factor affecting the decomposition efficiency of phosphate ore in the phosphoric acid process, followed by reaction temperature and reaction time. The dissolution behavior of Ca(H 2 PO 4 ) 2 was studied using phase diagrams of ternary systems of P 2 O 5 −CaO−H 2 O. When the ratio of the practical doses of phosphoric acid to the theoretical/ stoichiometric doses of phosphoric acid (Ratio P/T ) was 3.3 and the phosphoric acid concentration (calculated as P 2 O 5 ) was 35%, the decomposition efficiency of phosphate ore reached 98.34%, and the proportion of Ca(H 2 PO 4 ) 2 dissolved in the leach liquor reached 98.54%. A high proportion of dissolved Ca(H 2 PO 4 ) 2 reduced the loss of phosphorus, and the generation of clean gypsum was obtained under these experimental conditions. Clean gypsum produced by the phosphoric acid process is regular long columnar crystal and has few impurities. This study provides an efficient strategy for the production of phosphoric acid by controlling the dissolution of Ca(H 2 PO 4 ) 2 , while avoiding the generation of phosphogypsum.

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Recycling utilization of phosphogypsum in eco excess-sulphate cement: Synergistic effects of metakaolin and slag additives on hydration, strength and microstructure

Cited by 52 publications

References 80 publications

Preparation and Micromechanics of Red Sandstone–Phosphogypsum–Cement Composite Cementitious Materials

Preparation and Micromechanics of Red Sandstone–Phosphogypsum–Cement Composite Cementitious Materials

Effect of Vibration Procedure on Particle Distribution of Cement Paste

Study on Controlling the Dissolution of Calcium Dihydrogen Phosphate Using Ternary Phase Diagrams to Improve the Production Process of Phosphoric Acid

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