不同胶结材料对重金属污染土壤的固化效果

利用不同胶结材料对广西某铅锌矿场重金属污染土壤〔w(Pb)，w(Cd)和w(Zn)分别为4 375，79.33和13 470 mg/kg)〕进行固化处理.采用TCLP浸提液对固化体进行浸提，根据固化体的浸出性能，评价不同固化剂及辅助剂组合对重金属污染土壤的固化效果.结果表明:m(水泥)∶m(粉煤灰)∶m(生石灰)为2∶1∶1和1∶1∶2的固化剂组合具有很好的固化效果.水泥用量占固化体总量的30%时，3种重金属的固化率均达到99%；水泥+粉煤灰+生石灰固化体系的固化效果仅次于水泥，在m(水泥)∶m(粉煤灰)∶m(生石灰)为1∶1∶2和2∶1∶1时，30%的固化剂用量使3种重金属浸出质量浓度均满足危险废物填埋入场标准；水泥+粉煤灰和粉煤灰+生石灰固化体系的固化性能相对较差，粉煤灰参与固化反应表现出明显的滞后性，当用生石灰作为辅助剂参与反应时，粉煤灰中所含有的活性SiO₂和Al₂O₃在碱性条件下得到激发，从而进一步强化了粉煤灰的固化性能. 

Immobilization of Heavy Metal Contaminated Soil by Different Cementation Materials

A range of cementation materials were used to immobilize heavy metal contaminated soils sampled from a zinc-lead mine in Guangxi Province with contamination levels of 4,375 mg Pb/kg,79.33 mg Cd/kg and 13,470 mg Zn/kg.The solidified concretes were leached by extract liquid of TCLP,and the solidification efficiencies of different binders and adjuvant were evaluated based on the leaching performance of solidified products.Results indicated that the binders with the m(OPC):m(PFA):m(CaO)=2:1:1 and 1:1:2 were effective.With the treatment of 30% (w/w) OPC,the solidification efficiencies of each heavy metal were up to 99%.The combinations of cement (OPC),pulverized fuel ash (PFA) and quicklime (CaO) also showed good solidification performance,just inferior to OPC.The leached concentrations of three metals met the requirement of standard for security landfill site for hazardous wastes when 30% (w/w) binders in the ratio of m(OPC):m(PFA):m(CaO)=1:1:2 or 2:1:1 were used.OPC+PFA and PFA+CaO had lower solidification efficiencies with respect to the solidification reactions.The addition of PFA could result in hysteresis in the reaction.The reaction can be prompted with increasing mass ratio of CaO because alumina and silica can be activated in alkaline condition,therefore further intensifying the solidification efficiency of PFA.