基于碱渣的重金属污染土固化机理与应用研究

It is difficult for the high concentration of heavy metal contaminated soils to be efficiently solidified/stabilized using cement. Soda residue is an industrial waste residue. Disposal of soda residue not only takes up a lot of land, but also causes serious environmental pollution. Soda residue has a strong adsorption ability for heavy metal ions, and has a certain degree of cementation performance. This project investigates the efficiency utilization of soda residue for heavy metal contaminated soil solidification/stabilization. Firstly, the engineering properties of soda residue reinforced heavy metal contaminated soil are studied, the adsorption characteristics of soda residue for heavy metal ions and its mainly influencing factors are discussed, the interaction mechanism between soda residue and heavy metal contaminated soil is revealed using soil electrical resistivity measurement. Secondly, the method to solidification/stabilization of heavy metal contaminated soil with soda residue and cement is investigated, the influence of temperature, humidity and pH value of environmental conditions on the stabilization effect is discussed, a reasonable proportion of soda residue-cement mixture additives is recommended. Thirdly, based on the analysis of physical-chemical reaction, microstructure of stabilized contaminated soil during curing,the physical and chemical process and the changes in stabilized soil microstructure is studied, the mechanism of solidification/stabilization of heavy metal contaminated soil with soda residue and cement additives is revealed. Lastly, the long-term stability of soda residue stabilized contaminated soil suffering from cyclic wetting and drying effect, acid ,alkaline and sulfate solution penetration are studied, the mechanism of the changes in engineering properties and microstructure characteristics of solidified/stabilized contaminated soil is revealed, the proportion of soda residue-cement additives is optimized, a reasonable quality assurance and quality control (QA/QC) techniques is put forward. The project study not only has important theoretical significance and academic value, but also promotes waste recycling and improves the environment, has a broad application prospect.

针对高浓度重金属污染土难以有效固化的难题，考虑到工业废渣-碱渣对重金属离子的良好吸附作用，着重研究利用碱渣固化重金属污染土的方法。首先，研究碱渣加固重金属污染土的工程性质，掌握碱渣吸附金属离子的特性及影响因素，通过电阻率测试，揭示碱渣-污染土相互作用机理；其次，研究基于碱渣与水泥的固化重金属污染土方法，分析固化效果，探讨不同温度、湿度和pH值环境条件对固化效果的影响,获得固化剂合理配比初步方案；第三，通过对不同养护龄期下固化土的物化分析、微结构以及电阻率测试，掌握碱渣固化污染土的物化反应过程、微结构变化规律，揭示碱渣固化污染土的微观机制；第四，试验模拟在干湿循环及酸、碱和硫酸盐二次污染作用下，碱渣固化污染土的稳定性特征，掌握其工程性质及微结构变化规律，揭示其微观作用机制，优化碱渣固化技术。本项目研究不仅具有很好的理论意义和学术价值，而且可实现废物再生利用、改善环境，有着广阔的应用前景。

针对高浓度重金属污染土难以有效固化的难题，考虑到工业废渣-碱渣对重金属离子的良好吸附作用以及碱渣具有一定的硬凝作用，本项目着重研究利用碱渣固化/稳定重金属污染土的方法。.（1）通过试验研究了碱渣加固重金属污染土的工程性质，掌握了碱渣吸附金属离子的特性及影响因素；通过电阻率测试、XRD、SEM等微观测试分析，揭示了碱渣-污染土相互作用机理。.（2）重点研究基于碱渣与水泥的固化重金属污染土方法。分析碱渣-水泥固化重金属污染土的工程性质与固化效果，探讨了不同温度、湿度和pH值环境条件对固化效果的影响,获得了固化剂合理配比初步方案。.（3）通过对不同养护龄期下固化土的物化分析、微结构以及电阻率测试，掌握了碱渣固化污染土的物化反应过程、微结构变化规律，揭示了碱渣固化污染土的微观机制。.（4）通过试验模拟在干湿循环及酸、碱和硫酸盐二次污染作用下，碱渣固化污染土的稳定性特征，掌握了其工程性质及微结构变化规律，初步揭示了其微观作用机制，优化了碱渣固化技术。.本项目研究不仅具有很好的理论意义和学术价值，而且可实现废物再生利用、改善环境，有着广阔的应用前景。