SOLUBILITY MODEL FOR THE PORE SOLUTION OF LEACHED CONCRETE CONTAININGSOLIDIFIED WASTE

The long term behaviour of leached blocks of solidified wastes must be modeled from the results of laboratory experiments in order to predic t the conditions of a long and safe storage. The solidification with P ortland cement of two wastes has been studied: air pollution control r esidues from municipal solid waste incineration (named REFIOM) and sla g from lead secondary smelting (named SCORIE). Both wastes are essenti ally composed of mineral salts and contain a high level of heavy metal s such as Pb. Long term laboratory leaching experiments (more than 1 y ear duration) allowed us to observe the release of the soluble species . The leaching experiments were performed by contacting the blocks wit h pure water. A very good fit of the experimental results with the sim ulated data has been obtained by using a 3 dimension diffusional model for the very soluble ions (Na). In contrast to this situation, the re lease of heavy metals (Pb) is controlled by the chemical interactions within the solid matrix and by the changes in the pore water compositi on. The simple diffusion model must be improved in order to include th ese phenomena.