New technology for the abatement of SO{sub}2 in non-ferrous pyrometallurgical processes by a dry limestone scrubber

摘要

The neutralization process of SO{sub}2 from coal burning plants is a well-defined technology using limestone to form CaSO{sub}4 according to the following reaction: CaCO{sub}3 + SO{sub}2(g) + (1/2)O{sub}2(g) = CaSO{sub}4 This paper presents the results of a study carried out to validate the option of capturing SO{sub}2 using gases from a non-ferrous smelter; SO{sub}2 content was up to 12% using a three-stage fluidized bed reactor. The difference in SO{sub}2 content affects equilibrium conditions and kinetics, rendering a direct extrapolation of the high efficiency achieved for low SO{sub}2 content impossible. The R&D program consisted of a laboratory study using a semi-pilot operation of a one-stage fluidized bed reactor and the construction and operation of a three-step reactor prototype. Results show that the reaction proceeds according to the unreacted core model that imposes a compromise between CaCO{sub}3 conversion and SO{sub}2 capture. For high SO{sub}2 capture, the calcine from the reactor contained CaSO{sub}4 and CaO. A complete capture of SO{sub}2 from gases with 8 vol.% can be achieved with a mean reaction time of two hours at 800℃.