Abstract: This study investigates the effects of water-washing process（such as water to ash weight ratio, contact time, temperature, and number of extraction steps）of fly ash on the removal of the soluble chloride salts, and the effect of sintering on heavy metal stabilization. The results indicate that more than 93% of Cl is found to be leached at L/S=4. The ratio of liquid to solid is thought to be mostly responsible for the extraction of chlorine, and the extractible amount of chlorine have a good linear relationship with logarithm of L/S. Simultaneously, the reduction of chloride salt and the formation of relatively low-melting point calcium-containing aluminosilicates are identified by X-ray diffraction (XRD) techniques. Compared with the original fly ash, the washed fly ash has a lower leaching concentrations of heavy metals (Pb、Cd、Ni) after sintering. The heavy metal leaching toxicity of the washed fly ash can evidently meet demand of the regulation after sintering at 800℃. The technology combining the water-washing process with sintering has a good promising for the incinerator fly ash to reduce the leaching toxicity of heavy metals.

Key words: fly ash, water-washing process, chloride salt, sintering, heavy metals

摘要： 本试验以去离子水作为洗脱剂，考察了水洗前处理工艺（包括水灰比、水洗时间、水洗温度以及水洗次数）对飞灰中可溶性氯盐的洗脱效果。在此基础上对比研究了水洗工艺对飞灰烧结过程中重金属的稳定化促进效果。结果表明：在液固比为4时，水洗过程中约有93％的氯离子被洗脱而进入水相；水灰比是影响氯离子洗脱效果的最主要因素，氯离子洗脱量与水灰比的对数值呈现很好的线性关系；XRD结果证明了水洗过程中大量氯盐的洗脱以及低熔点含钙铝硅化合物的形成；同原始飞灰相比，水洗飞灰经烧结后其中的Pb、Cd、Ni的浸出浓度明显降低。800 ℃下烧结水洗飞灰可以使其中的重金属稳定化，浸出浓度均低于相应的标准限值。水洗工艺与烧结稳定化技术相结合明显降低了重金属的浸出毒性。

关键词: 飞灰, 水洗, 氯盐, 烧结, 重金属