TREATMENT OF MSW FLY ASHES IN PLASMA REACTOR: MONITORING OF CHLORINATED COMPOUNDS DESORPTION BY MASS SPECTROMETRY

In the present work, an RF low-pressure plasma reactor has been developed in order to study the desorption of chlorinated compounds from MSW fly ashes. Due to chemical complexity of a real MSW fly ashes, we have developed a model of fly ashes using a matrix of alumina, calcium oxide, silica and zeolites spiked with halogens and metals. Plasma/simulated fly ash interaction has been studied by on-line mass spectrometry.
Experiments have been performed with and without discharge, in order to point out the plasma chemical reactivity on chlorine desorption. Under plasma conditions, the main chlorinated compounds formed are Cl₂, HC1 and COCl₂. The composition of the chlorinated effluents depends on the nature of the plasma. The main results are the trapping of chlorine when hydrogen is added and the formation of phosgene when carbon and oxygen are added. The use of a fluidized bed of calcium oxide particles can reduce strongly toxic effluent emissions.