Heavy Metals Behavior During Thermal Plasma Vitrification Of Incineration Residues
- Laboratoire d'Analyse Spectroscopique et d'Energetique des Plasmas UPRES-EA 3269, Faculte des Sciences, Site de Bourges, Universite d'Orleans, Rue Gaston Berger, BP 4043, 18028 BOURGES Cedex (France)
- Laboratoire de Chimie des Plasmas, Universite de Limoges, 123 Avenue Albert Thomas, 87060 Limoges (France)
Incineration of wastes, widely and increasingly used nowadays, produces residues, mainly bottom ash and filter fly ash. Fly ash is especially problematic because of its high content in heavy metals easily drawn out. Thermal processes, based mainly on electrical arc processes, are used to melt the residues at high temperature and convert them into a relatively inert glass. Consequently, to improve the process and get a glass satisfying regulation, control of heavy metals (lead, zinc, cadmium and chromium...) volatility during plasma fly ash melting and vitrification is needed and basic data concerning vaporization of these metals are required. According to the volatility of these compounds observed during vitrification of fly ash, a predictive model has been used to simulate the elimination of Pb, Zn and S from the melt as a function of time and temperature for a system including chlorides, oxides and sulfates. The objective of this work was the experimental study of heavy metals volatility using optical emission spectroscopy. A twin torch plasma system, mounted above a cold crucible with Ar (or Ar + O2) as plasma gas, has been used. The crucible was filled with synthetic glass in which known amounts of metallic salts were added to obtain the same chemical composition as used in the model. From spectral lines intensities of Ar, the plasma temperature profiles along the observation direction has been first established, before using ratios of spectral lines of Ar and metallic (Pb, Zn) or Cl vapors to reach the evolution of the elements concentrations above the melt. Off-gases have been analyzed by mass spectrometry. The influence of the atmosphere (Ar or Ar + O2) above the crucible has been studied and differences in elements behaviors have been pointed out. The results of the spectroscopic measurements have been compared to the ones issued of modeling, in order to validate our model of vaporization.
- OSTI ID:
- 20797881
- Journal Information:
- AIP Conference Proceedings, Vol. 812, Issue 1; Conference: PLASMA 2005: International conference on research and applications of plasmas; 3. German-Polish conference on plasma diagnostics for fusion and applications; 5. French-Polish seminar on thermal plasma in space and laboratory, Opole-Turawa (Poland), 6-9 Sep 2005; Other Information: DOI: 10.1063/1.2168806; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature
Formation, composition and particle size distribution of fly-ashes from biomass combustion plants