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Project: 9141 #G890

The disposal and utilization of ashes from high temperature processes that use Ca-based sorbents for sulphur capture can be problematic. Such ashes often have various undesirable properties such as a highly exothermic reaction with water, the production of high pH leachate and destructive expansion, both in the landfill and when used in cementitious application. This report looks at the use of the CERCHAR and ash water dense suspensions (AWDS) process with CFBC and LIFAC ash residues. It also provides the first significant LIFAC ash for geotechnical appliations.

CERCHAR is a process which quantitatively converts the free lime in residues to slaked lime at elevated temperatures and pressures. In this way, formation of compounds such as ettringite are suppressed, leaving them potentially available for cemenntious appliations. The AWDS process was originally developed for use with conventional coal ash residues, and produces pumpable dense ash slurries which can subsequently set up to a "soft" rocklike consistency. These have been used both for surface disposal, and applications such as mine backfill.