Insolubility of Hazardous Heavy Metals in Wet Fly Ashes of MSW

在本研究中，将潮湿的飞灰放置并放置在泥土中，洗脱试验结果表明，铅、镉等有害重金属在一种我们称之为“飞灰自稳定”的过程中变得不可溶。对来自日本各地的48个不同样品进行的实验表明，这种稳定化与焚烧厂的类型或废气处理方法无关。在此稳定过程中，随着重金属的不可溶，30d后飞灰溶液的pH和碱度也有所下降，从pH依赖性测试结果可以看出，湿样品中重金属的释放量比原来的Dy样品低。因此，我们得出结论，重金属被捕获到了化学稳定的化合物中。空气中CO_2浓度越高(在0*CO_2*30%范围内)，重金属的不溶速度越快。实验结果表明，CO_2与其他化合物反应生成的碳酸盐对重金属有捕获作用。

In this research, moisturized fly ashes have been placed and left at loal tcmpeatures, and as the elution test results show, it was found that hazardous heavy metals such as Pb and Cd had become insoluble in a process we have called" Fly ashes self-stabilization". The experiments conducted with 48 diferent samples from all over Japan indicate that this stabilization dose not depend on the type of incineration plant or method of exhaust gas treatment. Under this stabilization process, as the heavy metals became insoluble, pH and alkalinity of the fly ashes solution also decreased After 30 days, from the results of the pH depended test, it was clear that the amount of released heavy metals in the wet samples was lower than the original dy samples. Therefore, we concluded that the heavy metals hal been trapped into chemical stable compounds. Also the higher the concentration of CO_2 in the air ( within a range 0*CO_2*30%), the faster the heavy metals became insoluble. As a conclusion, the expenment results suggest that the heavy metals were trapped in the carbonates formed by the reaction between CO_2 and other chemical compounds.