Modelling chemical interactions at a waste/waste interface

Abstract

The interfacial phenomena between an acidic and an alkaline fly ash were observed in small diffusion tubes using a slicing technique. pH profiles were determined by extracting each slice with water while a zinc profile was measured using a radioactive tracer. The alkaline fly ash slowly neutralized the acidic ash, resulting in precipitation of the zinc within the acidic ash, near the interface. A numerical model, based on transport by diffusion in the pore water and on instantaneous chemical reactions of neutralization and precipitation, was used to describe the observed phenomena.