Investigation of accelerated carbonation for the stabilisation of MSW incinerator ashes and the sequestration of CO₂

Abstract

Accelerated carbonation has been used for the treatment of contaminated soils and hazardous wastes, giving reaction products that can cause rapid hardening and the production of granulated or monolithic materials. This technology provides a route to sustainable waste management and it generates a viable remedy to the problems of a decreasing number of landfill sites in the UK, global warming (due to greenhouse gas emissions) and the depletion of natural aggregate resources, such as sand and gravel. The application of accelerated carbonation (termed Accelerated Carbonation Technology or ACT) to sequester CO2 in fresh ashes from municipal solid waste (MSW) incinerator/combined heat and power plants is presented. The purpose of this paper is to evaluate the influence of fundamental parameters affecting the diffusivity and reactivity of CO2 (i.e. particle size, the reaction time and the water content) on the extent and quality of carbonation. In addition, the major physical and chemical changes in air pollution control (APC) residues and bottom ashes (BA) after carbonation are evaluated, as are the optimum reaction conditions, and the physical and chemical changes induced by accelerated carbonation are presented and discussed.