钢渣作为钾盐矿充填料胶结剂的固化机理

Hydration mechanism of using steel slag as binder for backfill materials in potash mines

以有效解决钾盐矿尾盐和尾液导致的环境污染、资源浪费、安全隐患等问题为出发点,以改善钾盐矿充填料流动度和强度为目的,利用钢渣水化反应缓慢持久的特点,制备了以钢渣为胶结剂的钾盐矿充填料,初步证明钢渣细度和养护温度对充填料的性能有较大影响.所制备的充填料8 h内流动度保持在200 mm以上,28 d抗压强度可达2 MPa,满足充填料的性能要求.本文着重从微观角度分析了其固化机理,X射线衍射技术、扫描电子显微镜、热重分析、红外分析等分析结果表明：钢渣粉与钾盐矿尾液水化反应的产物主要为C-S-H凝胶、水铝钙石（或称费里德尔盐）、类水滑石等,在水化反应过程中水化产物之间相互穿插包裹使体系结构的致密度和强度不断增长.在微观结构呈层状的水铝钙石和类水滑石中出现类质同象代替现象,Ca2＋、Mg2＋、Fe2＋,Fe3＋、Al3＋和Si4＋都可相互取代而使得OH-和Cl-参与其中,这对体系中的杂质离子起到固定作用,对充填料的稳定性有利.该研究结果初步表明钢渣具有充当钾盐矿充填料胶结剂的潜力.

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 CS-H gels,hydrocalumite（or Friedel＇s salt）,and brucite. They are interspersed with each other so that the density and strength im-prove. 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 H2 O 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.