Preparation of geopolymer for building by mechanical activation process
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摘要: 利用钒钛磁铁矿尾矿制备地聚合物，既减轻了尾矿的污染，又实现了尾矿的高效利用。以承德某钒钛磁铁矿尾矿为主要原料，采用机械活化工艺制备地聚合物，探讨活化时间对尾矿的粒度、结构与地聚合物制品抗压强度的影响。结果表明：延长活化时间减小了尾矿粒度，破坏了矿物的晶体结构，从而增大了尾矿中活性硅与活性铝的浸出浓度，赋予地聚合物较高的抗压强度。当尾矿活化3.0 h后，采用尾矿与高岭土的质量比为6：4，Ca(OH)2和Na2SiO3的掺量均为10%、胶砂比为1∶1.5、液固比为0. 20的工艺条件，可制备出28 d 抗压强度高达50 MPa的地聚合物。样品的重金属离子浸出浓度符合国家标准。无定型的铝硅酸盐凝胶相及少量的沸石结合紧密，赋予制品较高的强度。Abstract: Using vanadium-titanium magnetite tailings for preparation of geopolymer can not only reduce pollution of the tailings, but also realize the efficient utilization of the tailings. The geopolymer was prepared from vanadium-titanium magnetite tailings in Chengde by mechanical activation process. The effect of activation time on the particle size and microstructure of the tailings and the compressive strength of the geopolymer products were investigated. The results show that prolonging the activation time can reduce the particle size and destroy the crystal structure of the tailings, which can increase the leaching concentration of active silicon and aluminum in the tailings and improve the compressive strength of the geopolymer. At the activation time of 3 h, mass ratio of tailings to kaolin of 6∶4, Ca(OH)2 and Na2SiO3 addition respectively of 10%, ratio of mortar to sand of 1∶1.5 and liquid-solid ratio of 0.20, the geopolymer with the 28-day compressive strength up to 50 MPa can be obtained. The leaching concentration of heavy metal ions in the sample meets the national standard. The amorphous aluminosilicate gel phase is tightly bonded with a small amount of zeolites, endowing the products with a high compressive strength.
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图 1 经不同时间活化后尾矿的XRD谱
Figure 1. XRD patterns of tailings after activation for different time
图 3 尾矿中活性硅与活性铝的浸出浓度随活化时间的变化曲线
Figure 3. Variation of leaching concentration of active silicon and aluminum in tailings with activation time
图 4 地聚合物抗压强度随活化时间的变化曲线
Figure 4. Compressive strength curves of geopolymer with activation time
表 1 尾矿和偏高岭土的化学组成
Table 1. Chemical compositions of tailings and kaolin
% 原料 SiO2 Al2O3 Fe2O3 CaO MgO Na2O K2O TiO2 SO3 V2O5 LOI 尾矿 56.89 12.56 6.39 9.65 1.26 2.63 1.69 1.50 5.39 0.02 2.02 高岭土 40.29 46.98 0.62 0.09 0.29 0.33 0.96 0.52 0.12 — 9.80 
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表 2 经机械活化后尾矿的粒度分布及比表面积
Table 2. Particle size distribution and specific surface area of tailings after mechanical activation
活化时间/h −10 µm含量/% d50/µm d90/µm 比表面积/
（m2·g−1）0 40.26 19.55 78.12 0.30 0.5 50.96 16.34 60.58 0.43 1.0 58.38 12.69 45.23 0.52 1.5 64.22 9.64 35.12 0.86 2.0 70.69 6.97 27.92 0.95 2.5 75.16 4.47 22.64 1.13 3.0 80.22 2.95 17.31 1.20 3.5 83.69 1.94 15.55 1.22
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表 3 样品重金属浸出浓度与相关标准要求
Table 3. Leaching concentration of heavy metals of the sample and the related standard requirements
mg/L Cu Pb Cd Cr Zn 含量 2.33 3.69 0.67 11.06 19.28 标准限值 <3.00 <5.00 <1.00 <15.00 <100.00
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