Identification and characterization of volatile species produced by plasma arc vitrification of mixed waste surrogates
- Mississippi State Univ., MS (United States); and others
Plasma arc vitrification testing was performed at Mississippi State University during Spring 1995 on mixed hazardous waste surrogates for the purpose of testing refractory materials. Because of the interest in partitioning of toxic and/or radioactive species between the melt and the gas phase, emission spectroscopy studies were performed to identify and characterize the volatile species present inside the primary thermal treatment chamber during plasma arc vitrification. The tests were conducted using a Plasma Energy Corporation PT-150 torch, operating in the transferred mode on air. The surrogate material was melted in a batch mode operation inside graphite crucibles. The torch was operated at an average power of 100 kW with an average air flow rate of 0.5 L/sec. The crucible was installed with four optical ports. One was used for a television camera to provide real-time images of the melt and two were used for emission spectroscopy as reported here and for two-color pyrometry. The last port was installed with a feed tube with a dual valve interlock system for dropping surrogate material into the crucible during testing. Results show that the plasma torch melted surrogate waste exhibits an emission spectra rich in gas phase atomic and diatomic species superimposed on a blackbody continuum. Rapid changes in intensities and spectral features alternated with relatively long periods of relatively stable spectra. Emission lines were positively identifies for Al, C, Ca, Ca+, Cu, Cr, Cs, Fe, K, Li, N, Na, O, Rb, and Si. Tentatively identified were Ni, Mn, and Ti. Intermittent spectral features have been tentatively identifies as N{sub 2}, Cd, and Pb. From this study it appears that emission spectroscopy would be of use in monitoring the gas phase emissions above a plasma torch melt process.
- OSTI ID:
- 210166
- Report Number(s):
- CONF-9509139--
- Country of Publication:
- United States
- Language:
- English
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