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氟石膏对高水充填材料性能的影响

The effect of fluorogypsum on the properties of high-water filling materials

  • 摘要: 充填开采是实现矿山绿色开发的重要途径,其中高水充填材料由于凝结时间短等优点,得到了广泛应用。该材料中40%的原料是天然硬石膏,主要组成是无水硫酸钙(CaSO4)。氟石膏是生产氢氟酸产生的工业固废,其主要组成是II型CaSO4,为探究氟石膏(F1,石灰掺量3%;F2,石灰掺量5%)对高水充填材料性能的影响,研究在不同试验水温下水胶比(质量比)为3∶1时,氟石膏掺量对高水充填材料凝结时间及1、7和28 d抗压强度的影响,同时通过XRD、SEM和TG-DTA研究其水化机理。结果表明在不同试验水温下,随着氟石膏掺量的增加,高水充填材料的凝结时间逐渐增加。随着F1掺量的增加,低掺量对高水充填材料不同龄期的抗压强度影响较小,其掺量高于20%时,高水充填材料1、7和28 d的抗压强度是逐渐减小的;随着F2掺量的增加,高水充填材料1、7和28 d的抗压强度是逐渐增加的,在不同龄期,与空白组相比,F2掺量80%,其抗压强度最大增长率为29.7%。微观分析得出高水充填材料的水化产物主要有AFt,Al(OH)3(gel)和CaSO4·2H2O,水化1 d后,F2组(F2掺量80%)的水化速率快、AFt生成量最大,空白组水化速率最小,AFt生成量最小;水化28 d后,3组的AFt生成量相当。同时,基于高水充填材料的水化动力学,分析了氟石膏对高水充填材料水化过程的影响,得出氟石膏可以取代高水充填材料体系中的天然硬石膏,应用于高水充填材料体系。

     

    Abstract: Filling mining is an important way to realize the green development of mines. High-water filling materials have been widely used because of their short setting time. In this material, 40% of the raw material is natural anhydrite, and the main component is anhydrous calcium sulfate (CaSO4). Fluorogypsum is an industrial solid waste produced in the production of hydrofluoric acid. Its main composition is type II CaSO4. In order to explore the influence of fluorogypsum (F1, lime content of 3%; F2, lime content of 5%) on the performance of high water filling materials, the influence of fluorogypsum content on the setting time and 1, 7 and 28 d compressive strength of high-water filling materials at different experimental water temperatures and water binder ratio of 3∶1 was studied. At the same time, the hydration mechanism was studied by XRD, SEM, and TG-DTA. The results show that the setting time of high-water filling material increases gradually with the increase of fluorogypsum content at different experimental water temperatures. With the increase of F1 content, the low content has little effect on the compressive strength of high-water filling materials at different ages. When its content is higher than 20%, the compressive strength of high-water filling materials at 1, 7, and 28 days decrease gradually; with the increase of F2 content, the compressive strength of the high water filling material increases gradually at 1, 7, and 28 d. At different ages, compared with the blank group, the F2 content is 80%, and the maximum growth rate of its compressive strength is 29.7%. Microscopic analysis shows that the hydration products of high-water filling materials mainly include AFt, Al (OH) 3 (gel), and CaSO4 · 2H2O. After hydration for 1 d, the hydration rate of the F2 group (80% of F2) is fast and the amount of AFt is the largest, while the hydration rate of the blank group is the smallest and the amount of AFt is the smallest; After 28 d of hydration, the amount of aft produced in the three groups was the same. At the same time, based on the hydration kinetics of high-water filling material, the influence of fluorogypsum on the hydration process of high-water filling material is analyzed. It is concluded that fluorogypsum can replace natural anhydrite in high-water filling material systems and be applied to high-water filling material systems.

     

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