Reuse of phosphogypsum pretreated with water washing as aggregate for cemented backfill

Zhou, Yanan; Li, Xibing; Shi, Ying; Zhu, Quanqi; Du, Jing

doi:10.1038/s41598-022-20318-0

Cited by 11 publications

(2 citation statements)

References 38 publications

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“…Without the addition of IT (PBS), the phosphate concentration in the slurry decreased gradually. This was because the hydration reaction of the binder produced a large amount of Ca 2+ , which combined with the phosphate to form precipitates such as calcium phosphate salt [ 39 , 40 ]. In comparison, with the help of ITs, the rate of decrease in the phosphate concentration was more remarkable.…”

Section: Resultsmentioning

confidence: 99%

Using Iron Tailings for Phosphate Removal in Cemented Phosphogypsum (PG) Backfill

et al. 2022

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Compared with the post-treatment of pollutants, such as the removal of phosphate from wastewater, it is more important to develop effective emission control strategies to reduce phosphate pollution. Phosphogypsum (PG) is a typical solid waste byproduct of phosphate production and contains high amounts of residual phosphate. In order to control the phosphate emissions during the recycling of PG aggregates for cemented backfill, another solid waste product—iron tailings (ITs)—was added during the preparation of backfill slurry. The results showed that the ITs effectively accelerated the phosphate removal in cemented PG backfill, enabling the quick reduction in the phosphate concentration to the discharge standard (<0.5 mg/L) within 15 min. This means that the emissions of phosphate to bleeding water were effectively controlled. The adsorption experiment showed that phosphate was adsorbed by the ITs, and the adsorption data fitted well with the Langmuir adsorption model (R2 = 0.98) and pseudo-second-order kinetic model (R2 = 0.99), indicating that the phosphate adsorption of ITs was a monolayer chemical adsorption. Furthermore, an unconfined compressive strength (UCS) test was performed on the backfill with the addition of ITs. Compared to the control group (without ITs), the UCS of backfill with 20% ITs increased from 1.08 MPa to 1.33 MPa, indicating that the addition of solid waste could be beneficial to the strength development of the backfill by mitigating the interference of phosphate with the hydration process. The backfill cured for 28 d was selected for the toxic leaching test, and the phosphate concentration in the leachates was always below 0.02 mg/L, indicating that ITs can effectively immobilize phosphate in backfill for a long time.

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Section: Resultsmentioning

confidence: 99%

Using Iron Tailings for Phosphate Removal in Cemented Phosphogypsum (PG) Backfill

et al. 2022

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“…At present, the commonly used pretreatment methods mainly include water washing, lime neutralization, calcination, ball milling, etc. [ 23 , 24 ]. In addition, the evaluation of radioactive elements ( 238 U, 226 Ra, 228 Ra, 210 Pb, 232 Th, and 40 K, etc.)…”

Section: Introductionmentioning

confidence: 99%

Effects of Pretreated Phosphogypsum and Granulated Blast-Furnace Slag on the Rheological Properties of the Paste Excited by NaOH

Dong

Chen

et al. 2023

Molecules

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The main component of phosphogypsum (PG) is CaSO4·2H2O. PG contains a few impurities, heavy metals, and radioisotopes, which limit the use of PG and pose a danger to the environment. In this study, under the excitation of a sodium hydroxide solution, the rheological properties of a paste with granulated blast-furnace slag (GGBS) and PG treated with ultrasonic water washing were investigated. Experimental results showed that the ratio of GGBS to PG and the amount of sodium hydroxide solution significantly affect the density and viscosity of the paste, but the effect patterns of both are different. The maximum viscosity was 498 mPa·s when the ratio of GGBS to PG was 4:1. When the ratio changed from 3:2 to 1:4, the viscosity of the paste gradually decreased by 15.5%, 32.1%, 36.1%, and 46.8%, respectively. In contrast, the ratio of GGBS to PG had a greater effect on the viscosity than the amount of sodium hydroxide solution in terms of the standard consistency water consumption, viscosity, and water release ratio. The larger the PG ratio, the smaller the density, viscosity, and water release ratio of the paste. The variation in the ratio of GGBS to PG had a significant effect on the water film thickness of the paste, demonstrating that the larger the PG mixture, the larger the water film thickness of the paste, which reached 1.122 μm, 2.31 times the minimum water film thickness of the paste. At the same time, the water film thickness of the paste was negatively correlated with the water consumption of the standard consistency, viscosity, and water release ratio, and was positively correlated with the fluidity.

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Cemented backfill using Ca(OH)2-pretreated phosphogypsum as aggregate: Hydration characteristics, structural features and strength development

Min,

Shi,

et al. 2023

Construction and Building Materials

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Reuse of phosphogypsum pretreated with water washing as aggregate for cemented backfill

Cited by 11 publications

References 38 publications

Using Iron Tailings for Phosphate Removal in Cemented Phosphogypsum (PG) Backfill

Using Iron Tailings for Phosphate Removal in Cemented Phosphogypsum (PG) Backfill

Effects of Pretreated Phosphogypsum and Granulated Blast-Furnace Slag on the Rheological Properties of the Paste Excited by NaOH

Cemented backfill using Ca(OH)2-pretreated phosphogypsum as aggregate: Hydration characteristics, structural features and strength development

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