Study of leaches obtained from the disposal of fly ash from PFBC and AFBC processes

Several works have been carried out in relation to the disposal of residues from conventional coal combustion processes [1,2]. However, these residues are different from those proceeding from fluidised bed combustion systems, mainly due to the sorbent (limestone or dolomite) used to the removal Of S O2 emissions. In this paper the environmental implications [3] of the disposal of residue s from fluidised bed combustion systems are studied. The procedures to eval uate the leaching behaviour of these residues have been done at three level s: shaking, column and lysimeter studies. Comparison between the three meth ods has been carried out, concluding that the results obtained with columns tests and lysimeter tests are very similar. So, to evaluate the environmen tal impact of fly ashes, it would not be necessary to do lysimeter tests (w hich are expensive and need a lot of time) in order to know the behaviour o f ashes once they are disposed of. (C) 2001 Elsevier Science B.V. All right s reserved.