筛选出多种无机药剂和有机药剂对江苏某地生活垃圾焚烧飞灰进行稳定化处理,在考察不同药剂对飞灰中重金属固定效果的同时,重点关注了药剂处理后飞灰体系的矿物学特性,分析了飞灰中 Pb、Cr、Cd 等重金属在矿物相和非矿物相的分布特性.结果表明:无机药剂中磷酸可显著降低Pb浸出浓度,从97.55mg/L降到2.16mg/L;有机药剂中聚二硫代氨基甲酸盐等3种药剂在2%~3%的药剂添加量下,Pb、Zn等重金属浸出浓度显著降低.原灰中Pb和Cd主要分布在矿物相中,Cu、Cr和Zn主要分布在非矿物相中.无机药剂和有机药剂的添加会造成飞灰基体的溶解,可溶性离子移动和二次矿物的生成.螯合处理后,飞灰中非矿相含量从14.41%增加至21.52%,非矿物相中的Cr含量降低可能由于在螯合反应过程中转移至铬酸盐矿物相中,矿物中Cd含量显著增加可能由于螯合处理生成了含Cd沉淀矿物.螯合处理前后重金属在矿物中分布行为相似,Cr、Zn和Pb主要赋存于方解石中,Cr、Cu主要赋存于赤铁矿中.%Several effective inorganic and organic chemicals were screened to stabilize MSWI fly ash from a MSWI plant of Jiangsu province. The aim is not only to investigate the stabilization effect of heavy metals, but characterize the mineralogy of MSWI fly ash under different chemical treatments to determine the heavy metal (Pb, Cr, Cd, et al.) fractions in mineral and non-mineral phases. The results indicated that phosphoric acid was the best inorganic chemical to reduce the lead leaching from 97.55mg/L to 2.16mg/L in this experiment, while such three single organic chemicals (polydithiocarbamate) with the addition of 2%~3% can markedly decrease the heavy metal leaching. In the original MSWI fly ash, the distribution of lead and cadmium were in the mineral phases, whereas the copper, chromium and zinc in non-mineral phases. The inorganic and organic chemicals resulted in matrix materials dissolution, soluble ions diffusion and secondary mineral transformation. After chelating treatment, the non-mineral fraction raised from 14.41% to 21.52%. Meanwhile the chromium in the non-mineral fraction was transformed to chromates. The cadmium in the mineral fraction increased due to the precipitate formation. The distributions of heavy metals in mineral phases were analogical behaviours that the chromium, zinc and lead were presented in calcite and chromium and copper in hematite.
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