Volatilization and Separation Characteristics of Heavy Metals in Fly Ashes by Halogenation Reaction

Katsuya Nakayama*, Masahide Yamamoto**, Yoshinori Tanaka**
Shoji Ozawa** , Hitoki Matsuda** and Mitsuru Takada*,
* Environmental Division Research & Development Center, SHINTOKOGIO, LTD.
** Research Center for Advanced Waste and Emission Management, Nagoya University
+Correspondence should be addressed to Hitoki Matsuda:
(Furo-cho, Chikusa-ku, Nagoya-City, Aichi, 464-8603 Japan)

Abstract
The volatilization of such heavy metals as Pb, Zn, Cu and Fe in MSW (Municipal Solid Waste) molten fly ash was studied by applying HCl gas, converting these heavy metals into metal chlorides. As a result, volatilization of more than 98% of Pb and Zn was achieved for both MSW molten fly ash and MSW fly ash at 1173K. The volatilization of Fe was 85% and 100% for MSW molten fly ash and MSW fly ash at 1173K, respectively. The volatilization of Cu was lower than other metals in both fly ashes.
The effects of temperature and guantities of Na and K in the MSW molten fly ash on the volatilization of heavy metals were investigated, by employing model fly ash prepared under different treatment temperatures and mixing weights of Na and K. As a result, it was found that there was no significant difference in the volatilization of Pb, Zn, Cu and Fe for the treatment temperature of the model fly ash. Only Fe volatilization decreased with the increase of Na and K content. This result corresponded with the results of Fe volatilization for MSW fly ash and MSW molten fly ash.

Key words: heavy metal, volatilization, MSW molten fly ash, halogenations, hydrogen chloride