机械活化−碱激发制备钒尾矿基地聚物

Preparation of vanadium tailings based geopolymer by Mechano −alkali activation

  • 摘要: 利用钒尾矿制备地聚物不仅可以减少尾矿资源浪费,还可以保护环境。以钒尾矿为主体,辅以铝硅酸盐、偏高岭土为铝质校正料,标准砂为骨料,氢氧化钠、硅酸钠为碱激发剂制备地聚物,考察了机械活化、钒尾矿掺入量,碱激发对钒尾矿基地聚物性能的影响。结果表明,在钒尾矿机械活化时长为120 min、钒尾矿掺入量为45%、铝酸盐水泥40%、偏高岭土15%、水固比(质量比)为0.36、胶砂比(质量比)为5且采用NaOH(3%)+Na2SiO3(3%)复合钠碱激发剂时,所制成的地聚物抗折强度、抗压强度达到最高为4.98 MPa、32.1 MPa。对所制成的地聚物样品进行XRD、SEM等微观表征,发现样品中形成了无定形相N−A−S−H胶凝物质,表明钒尾矿可以成功用于制备地聚物,并且制备的地聚物具有良好的性能,为钒尾矿的综合利用提供了一种新的途径。

     

    Abstract: In response to the increasing output and low utilization rate of stone−coal vanadium tailings, this experiment focused on vanadium tailings as the main material, activated the vanadium tailings first, and then mixed the activated tailings, metakaolin, and aluminate cement evenly according to the specific ratios, added a certain amount of alkali activator, stirred and mixed the mixed samples thoroughly, and then added standard sand to form mortar. The mortar was injected into a mold with dimensions of Φ40 mm × 40 mm × 160 mm, formed under curing conditions of 101.325 kPa air pressure, and then placed in an environment of 60 °C and 95% humidity for accelerated curing until the specified ages (3 days, 7 days, 28 days). In this experiment, the effects of mechanical activation, vanadium tailings incorporation and alkali excitation on the properties of vanadium tailings base polymers were investigated under the condition of fixing the amount of aluminum corrector (40% aluminate cement and 15% metakaolin) and the water−solid ratio (mass ratio)of 0.36. The study investigated the effects of mechanical activation, the proportion of vanadium tailings, and alkali activation on the properties of geopolymers derived from vanadium tailings. The results showed that the highest flexural and compressive strengths of 4.98 MPa and 32.1 MPa were obtained when the vanadium tailings were mechanically activated for 120 minutes, with a proportion of 45% vanadium tailings, 40% alumina cement, 15% metakaolin, a water−to−solid ratio (mass ratio) of 0.36, a cement−to−sand ratio (mass ratio) of 5, and an alkali activator consisting of NaOH (3%) and Na2SiO3 (3%). Microscopic characterization of the prepared geopolymer samples, such as XRD and SEM, revealed the formation of amorphous phase N−A−S−H gellable substance, indicating that vanadium tailings can be successfully used to prepare geopolymers with good properties, providing a new approach for the comprehensive utilization of vanadium tailings.

     

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