炉渣-粉煤灰地聚合物固化铜污染土的试验研究

利用低钙粉煤灰、炉渣为原料制备的炉渣-粉煤灰地质聚合物（BA-FAG）作为固化剂，开展铜污染土的固化试验研究。通过无侧限抗压强度试验和毒性浸出试验，探讨了养护龄期、固化剂掺量及初始铜离子浓度对BA-FAG固化铜污染土效果的影响，并利用X射线衍射（XRD）分析、扫描电镜（SEM）测试及X射线光电子能谱（XPS）分析等手段进行了表征。结果表明，增大固化剂掺量及养护龄期，可以提高BA-FAG固化铜污染土的无侧限抗压强度（UCS），以及减少铜离子浸出，而污染土中初始铜离子浓度与固化土的强度负相关，并与毒性浸出浓度正相关；掺入20%和30%的BA-FAG可分别固化浓度不超过6000mg/kg与10000mg/kg的铜污染土，固化土28d的UCS值分别不低于0.358MPa和0.457MPa，且在酸性和中性淋滤下毒性浸出浓度均低于100mg/L；重金属铜在被BA-FAG物理封存过程中主要以Cu2+离子和Cu(OH)2沉淀的形式存在。

Experimental study on solidification of copper contaminated soil by fly ash based geopolymer with bottom ash

A laboratory investigation of solidification of copper contaminated soil by fly ash based geopolymer with bottom ash (BA-FAG) was carried out. The effects of curing time, binder content and initial copper content on the solidification of copper contaminated soil were studied by unconfined compressive strength (UCS) test, toxic leaching test, X-ray diffraction (XRD) test, scanning electron microscopy (SEM) test and X-ray photoelectron spectroscopy (XPS) test. The results show that the UCS value of BA-FAG solidified soil can be increased together with decrease of leaching concentration of copper ion by increasing binder content and curing time. The initial concentration of copper ion in contaminated soil is negatively correlated with the strength of solidified soil, and positively correlated with leaching concentration. The copper contaminated soil with initial concentration of no more than 6000mg/kg and 10000mg/kg can be solidified by 20% and 30% binder contents, respectively. Meanwhile, the UCS values of solidified soil at 28 days of curing are no less than 0.358MPa and 0.457MPa, respectively, and the leaching concentration is lower than 100mg/L at the conditions of both acidic and neutral leaching. The copper in the contaminated soil mainly exists in the form of Cu2+ and Cu(OH)2 precipitation during the physical encapsulation by BA-FAG.