STUDY ON LEACHED CHARACTERISTICS AND STABILITY OF HEAVY METAL IN CEMENTED MIXED SLUDGE
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摘要: 以某受重金属污染河道淤泥为研究对象,以水泥为主胶凝材料,粉煤灰和矿粉工业废弃物为辅胶凝材料,AlCl3、石膏为外加剂,对重金属污染河泥进行固化,并对固化试件进行了淋溶试验。通过单掺试验、正交试验筛选出固化淤泥材料的最优配比,然后对最优固化剂固化的试件进行长龄期养护试验及冻融试验。研究发现:当AlCl3掺量为4%,养护1 d时,淤泥含水率明显降低;水泥掺量为12%、矿粉掺量为14%、粉煤灰掺量为6%、石膏掺量为0.4%时,淤泥中的Ni、Cd、Pb、Hg四种超标重金属浸出浓度分别降低了78.04%、85.78%、67.79%、90.00%;冻融循环200次试验时,淤泥中的Ni、Cd、Pb、Hg四种超标重金属浸出浓度分别降低74.26%、83.75%、62.27%、88.62%;混合土养护至第300天时,淤泥中的Ni、Cd、Pb、Hg四种超标重金属浸出浓度分别降低85.42%、90.29%、78.84%、92.83%,结果均表明混合土的重金属浸出浓度符合CJ/T 340—2016《绿化种植土壤》的限制要求,拥有良好的稳定重金属的性能。Abstract: Taking river sludge polluted by heavy metal as research objects, using cement as cementitious material, industrial waste fly ash and mineral powder as auxiliary cementitious materials, AlCl3, gypsum as the admixture, the polluted sludge was cemented and the leaching tests were conducted on cemented specimens. The optimum proportion for cemented specimens of the minimum leached concentration of heavy metals was selected by the single mixing experiment and orthogonal experiment. The specimens cemented prepared by the optimal proportion were performed long-age curing tests and freeze-thaw tests. The results showed that when the AlCl3 content was 4% and curing age was 1 d, the water content of specimens decreased obviously. When the content of cement, mineral powder, fly ash and gypsum in specimens was respectively 12%, 14%, 6% and 0.4%, the leached concentration of Ni, Cd, Pb and Hg from spcimens decreased by 78.04%, 85.78%, 67.79% and 90.00%. The leached concentrations of Ni, Cd, Pb and Hg from specimens respectively decreased by 74.26%, 83.75%, 62.27% and 88.62% after 200 freeze-thaw cycles. The leached concentrations of Ni, Cd, Pb and Hg from specimens decreased by 85.42%, 90.29%, 78.84% and 92.83% respectively, when specimens were cured for 300 d. The results showed that the leached concentrations of heavy metals from specimens met the requirements of Specifications Planting Soil for Greening(CJ/T 340-2016) and the cemented soil had a good performance of stabilizing heavy metals.
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Key words:
- cemented heavy metal /
- sludge /
- long-age /
- industrial waste /
- freeze-thaw cycle
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