Hydration mechanism of using steel slag as binder for backfill materials in potash mines
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摘要: 以有效解決鉀鹽礦尾鹽和尾液導致的環境污染、資源浪費、安全隱患等問題為出發點,以改善鉀鹽礦充填料流動度和強度為目的,利用鋼渣水化反應緩慢持久的特點,制備了以鋼渣為膠結劑的鉀鹽礦充填料,初步證明鋼渣細度和養護溫度對充填料的性能有較大影響.所制備的充填料8 h內流動度保持在200 mm以上,28 d抗壓強度可達2 MPa,滿足充填料的性能要求.本文著重從微觀角度分析了其固化機理,X射線衍射技術、掃描電子顯微鏡、熱重分析、紅外分析等分析結果表明:鋼渣粉與鉀鹽礦尾液水化反應的產物主要為C-S-H凝膠、水鋁鈣石(或稱費里德爾鹽)、類水滑石等,在水化反應過程中水化產物之間相互穿插包裹使體系結構的致密度和強度不斷增長.在微觀結構呈層狀的水鋁鈣石和類水滑石中出現類質同象代替現象,Ca2+、Mg2+、Fe2+,Fe3+、Al3+和Si4+都可相互取代而使得OH-和Cl-參與其中,這對體系中的雜質離子起到固定作用,對充填料的穩定性有利.該研究結果初步表明鋼渣具有充當鉀鹽礦充填料膠結劑的潛力.Abstract: The depth and scale of potash mines is currently increasing. Backfill materials with higher homogeneity and greater fluidity property are required to prevent blocking and ensure that filling materials are transported safely to the underground mines. The production of low-cost backfill materials that meet both strength and transportability requirements is therefore extremely important. A potash filling material with steel slag as a cementing agent was prepared to solve the problems caused by potash tailings and brine water in potash mines, such as environmental pollution, resources waste, and potential safety issues. This was also done with the aim of improving the flow and strength properties of potash filling materials by using steel slag as binder because its hydration reaction is slow and durable. The results indicated that the fluidity and late strength met requirements. It was also initially proved that the steel slag fineness and curing temperature had a significant influence on the performance of the filling material. The fluidity of the filler was greater than 200 mm in 8 h and the compressive strength reached 2 MPa in 28 days, which satisfied the performance requirements for the filler. This article mainly focuses on the analysis of the curing mechanism from a microscopic point of view. The results of X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectrometer (SEM-EDS), thermogravimetry/differential thermal analysis (TG/DTA), and Fourier-transform infrared spectroscopy (FTIR) show that the products of the hydration reactions are primarily C-S-H gels, hydrocalumite (or Friedel's salt), and brucite. They are interspersed with each other so that the density and strength improve. The results show that isomorphous substitution occurs in the microscopic structure of the layered hydrocalumite and hydrotalcite. The Ca2+, Mg2+, Fe2+, Fe3+, Al3+, and Si4+ can replace each other and enable OH-, Cl-, and H2O molecules to be easily absorbed into the interlayer. In this way, impurity ions can be stabilized and stability of the filling material can be improved. The results of this study provide preliminary evidence that steel slag powder can be used as a binder in potash backfill material.
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Key words:
- steel slag powder /
- brine water /
- C-S-H gel /
- Friedel's salt /
- hydrocalumite /
- backfill material /
- isomorphism
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參考文獻
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