Highly Active Absorbent for SO₂ Removal Prepared from Coal Ash (Part 1)

Abstract

Coal ash samples from Batangas Coal-Fired Thermal Power Plant and limestone from a cement plant in Bulacan were used as raw materials for the preparation of highly active SO₂ absorbent. The prepared SO₂ absorbents were characterized to determine the effects of mineralogical composition, morphological structure and the type of coal ash used, on SO₂ removal efficiency/ The desulfurization activity of the SO₂ absorbents were determined by varying the curing conditions and CaO content.

Among the coal ashes, fly ash exhibited the highest SO₂ removal efficiency and longest effective absorption period. The SO₂ removal efficiency is closely dependent on the basic conditions during the preparation process of the SO₂ absorbents. The SO₂ absorptions activity increased with the reaction temperature and reached a maximum at 120⁰C for fly ash and 130⁰C for both bottom ash and slag. Maximum SO₂ removal efficiency was also attained by fly ash at 10 hour curing period. Bottom ash and slag had high activity at 15-20 hours of curing time. CaO content in the range of 20 ~30% will give a high SO₂ absorption activity.