Study on the Stability of Heavy Metals in Ceramsite Prepared Using Contaminated Soil

The disposal and remediation of heavy metal (HM)-contaminated soil has become a difficult problem, and the high-temperature roasting process of ceramsite preparation was proposed to be an effective method to solve the problem. Ceramsite can be used as a multifunctional material in different scenarios. However, there are few research reports on the potential environmental risks of residual HMs in ceramsite produced from contaminated soil. In this study, two types of soil were calcined at temperatures of 200-1100 degrees C to prepare ceramsite. Special attention was paid to evaluating the stability of HMs in ceramsite. The results of the SPLP, TCLP, and DTPA tests showed that the HM leaching concentrations in ceramsite were more than 99% lower than those before roasting, which indicates that the environmental risk of HMs in ceramsite was significantly reduced. The HMs were solidified by high-temperature calcination, and this can be confirmed by chemical morphology, mineral morphology, and microscopic structure analysis. Long-term acid rain extraction experiments showed that the peak release of HMs in ceramsite occurs in the first three years and then decreases to an ideal level. This study is of great significance to assess the stability of HMs in ceramsite prepared using contaminated soil.