Analysis of Dynamic Leaching Test About Heavy Metals in Solidification Body of Municipal Solid Waste Incineration Fly Ash

摘要

A new method, Dynamic Leaching Test (DLT), was put forward to analyse the leaching behaviour and leaching mechanism of heavy metals in solidification body of municipal solid waste incineration (MSWI) fly Ash. In this study, two groups of solidification materials were used, one with ordinary Portland cement (C), and the other with slag-and-clinker (SC). In each solidification body, solidification material/ (solidification material + MSWI fly ash) weight ratio was 25% and water/solid weight ratio was 0.3. After a 60-day curing period, DLT was applied to analyse the leaching behaviours and leaching mechanisms of lead and chromium in solidification body with a mathematical model based on Fick's first law. The test results showed that most of lead and chromium were leached out during the initial stage (0～7d), and their leachability decreased greatly later. In the cement-based solidification body, the leaching behaviour of chromium is approximately consistent with Fick's first law. The leaching of lead is a combination of diffusion and acid erosion mechanisms. In the slag and clinker-based solidification body, the leaching of lead is approximately consistent with Fick's First law. The leaching of chromium is more complicated than simple diffusion or acid erosion, which indicated the need for further research.