Management of FGD Residues
AUTHOR: Lee B. Clarke
DATE: October 1993
This report reviews the source and characteristics of residues from flue gas desulphurisation (FGD) systems and assesses current developments in the management of these materials. FGD processes improve the environmental performance of pulverised coal-fired plants by reducing emissions to the atmosphere. However, many FGD systems produce large quantities of solid residues. An integrated approach to pollution control requires that reductions in emissions do not result in an increase in pollution from solid wastes.
Under present regulations most FGD residues can be classified as non-hazardous wastes. Landfill is an established and simple way of disposing of most coal-use residues, but in future dumping may be unacceptable. In many countries regulations relating to disposal of materials are becoming more stringent and disposal costs are escalating. Some countries now favour, or even require, waste minimisation, such that disposal is only permitted where utilisation is not possible. By-products from FGD systems may be used in a variety of ways, including applications in agriculture, building and construction uses, and civil engineering. FGD gypsum can be produced to consistent, user defined specifications and has been used widely as a substitute f or natural gypsum. The variability of other FGD residues has discouraged commercial utilisation to date. As the quantities of residues increase, more varied and novel uses may become rnore important.