Effect of Zinc on the Reactivity of Calcium Carbonate toward Sulfur Dioxide

Abstract

The effect of Zn on the reactivity of precipitated and heavy calciumcarbonate, which have different physical characteristics, was investigated usinga fixed bed. The calcination rate(%) of each calcium carbonate increased by the addition of 1 wt % of Zn within 5 min at temperatures from 800 to 1000 C. Those of heavy calcium carbonate increased exceedingly, particularly 20-25% in about 2min at 900 and 950 C. This effect was also confirmed by high-temperature X-ray diffractien. In the reaction of calcium carbonate with SO2 (15 vol % in air), the conversion rates of heavy calcium carbonate to calcium sulfate were greater than those of precipitated calcium carbonate to it in a few minutes at temperatures from 800 to 1000 C. The values of the latter were 10.1, 25.4 and 56.2% after 5min at 800, 900 and 1000 C, respectively, while those of the former were 62.7, 80.0 and 81.4%. By addition of 1 wt % of Zn, heavy calcium earbonate showed an increase of the conversion rate above boiling point of Zn.