IS THE GLASS PHASE DISSOLUTION RATE ALWAYS A LIMITING FACTOR IN THE LEACHING PROCESSES OF COMBUSTION RESIDUES

The kinetic characteristics of waste glass phases in some coal fly ash es are simulated by the hydration free energy approach of multiple-com ponent glass. A geochemical model is used to calculate the dissolution processes of waste glass in a low flow-through system for coal fly as hes. The contribution of waste glass dissolution for the leaching of s olid waste is discussed on the basis of dissolution mechanisms and kin etics of glass phases, reaction time and disposal condition. It has be en found that the dissolution rate of a glass phase is not always a li miting factor in the leaching processes of coal fly ashes. Additional retention mechanisms may retard the release of toxic elements but only under some limited conditions. The disposal environment together with kinetic properties of waste glass phases need to be accounted, for th e dissolution of the glass phase. Glass dissolution under some, not im probable, circumstances may considerably contribute to the long-term r elease of toxic metals.