热活化铅锌尾矿基碱激发胶凝材料的制备及性能

摘要/Abstract

摘要： 以铅锌尾矿为主要原料,添加由矿渣、钢渣、氟石膏混合而成的辅助胶凝材料,以水玻璃和氢氧化钠为碱激发剂制备铅锌尾矿基碱激发胶凝材料。通过正交试验,探讨了水玻璃模数、水玻璃掺量及尾矿与辅助胶凝材料质量比对胶凝材料抗压强度的影响,并得出最佳原料配比。通过800 ℃、1 000 ℃、1 200 ℃的热处理,制备热活化铅锌尾矿基碱激发胶凝材料,并测试其性能。采用X射线衍射谱、傅里叶红外光谱和扫描电子显微镜对热活化前后尾矿和胶凝材料进行分析表征。结果表明,当水玻璃模数为1.8,水玻璃质量掺比为0.15,尾矿与辅助胶凝材料质量比为7 ∶3时,胶凝材料28 d抗压强度可达到20.68 MPa。胶凝材料内部形成大量水化硅酸钙(C-S-H)与硅铝多聚物构成三维网状结构,覆盖在尾矿晶体表面形成致密整体。当热活化温度为1 000 ℃时,胶凝材料28 d抗压强度达到28.05 MPa。热活化后的尾矿内部结构疏松,利于硅铝质在碱性条件下解聚,同时使得反应体系中生成了更多硅铝多聚体,取代了二聚体为主的C-S-H凝胶,为胶凝材料提供了更优良的抗压强度和早硬特性。此外胶凝材料对Pb、Zn重金属的固定作用极好,大幅降低了尾矿重金属Pb、Zn的毒性浸出浓度,有效解决了尾矿中重金属对周围环境的危害问题。

关键词: 铅锌尾矿, 碱激发胶凝材料, 热活化, 抗压强度, 硅铝多聚体, C-S-H, 重金属毒性浸出

Abstract: Alkali activated cementitious materials were prepared using lead-zinc tailings as the main materials and adding the supplementary cementitious materials which consist of slag, steel slag, and fluor gypsum. These raw materials were activated by an alkali activator composed of NaOH and sodium silicate.Through orthogonal test, the effects of the modulus of sodium silicate, the content of sodium silicate, and the mass ratio of tailings to supplementary cementitious materials on the mechanical strength of cementitious materials were discussed, and the optimal ratio of raw materials was obtained. Alkali activated cementitious materials based on thermally activated lead-zinc tailings were prepared using tailings that pretreated at 800 ℃, 1 000 ℃, and 1 200 ℃. X-ray diffraction analysis, Fourier infrared spectrometer analysis and scanning electron microscopic analysis were used to characterize tailings and cementitious materials before and after thermal activation. The results show that when the modulus of sodium silicate is 1.8, the mass ratio of sodium silicate is 0.15, and the mass ratio of tailings to supplementary cementitious is 7 ∶3, the compressive strength of the cementitious material is the highest. The compressive strength of 28 d reaches 20.68 MPa. Inside alkali activated cementitious material exists a generous three-dimensional network structure formed by C-S-H and silicon aluminum polymer which covers the surface of tailings crystal to form a dense matrix providing strength for cementitious materials. When the thermal activation temperature is 1 000 ℃, the compressive strength of cementitious material is enhanced to the greatest extent and the compressive strength of 28 d reaches 28.05 MPa. The internal structure of thermally activated tailings is looser which is conducive to depolymerization of aluminosilicate under alkaline conditions. Meanwhile, more silicon aluminum polymers instead of C-S-H gels were formed, which responsible for higher compressive strength and early hardening characteristics of cementitious materials. The cementitious materials can immobilize Pb and Zn in the internal structure and substantially reduce the leaching of Pb and Zn in tailings. The application of alkali activated cementitious materials may provide a solution to alleviate the harm of heavy metals in tailings to environment.

Key words: lead-zinc tailing, alkali activated cementitious material, thermal activation, compressive strength, silicon aluminum polymer, C-S-H, heavy metal toxicity leaching

中图分类号:

居辰轩, 王豪杰, 侯浩波, 周旻. 热活化铅锌尾矿基碱激发胶凝材料的制备及性能[J]. 硅酸盐通报, 2022, 41(6): 2071-2081.

JU Chenxuan, WANG Haojie, HOU Haobo, ZHOU Min. Preparation and Properties of Alkali Activated Cementitious Materials Based on Thermally Activated Lead-Zinc Tailings[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2022, 41(6): 2071-2081.

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