Highly Active Absorbent for SO₂ Removal Prepared from Coal Ash (Part 2)

Abstract

This paper is a sequel of previous study (Part 1) on the preparation of highly active absorbents for SO₂ removal from coal ash and limestone. The prepared absorbent from coal fly ash was tested for its desulfurization activity at varying conditions using the experimental SO₂ absorption analyzer. Simulated flue gas moisture used was composed SO₂, NO, CO₂, O₂ and H₂O. The activity of the produced absorbent closely depends on the method of preparation taking into account the effect of time and temperature for curing and drying. The effects of particle size, surface area and % glass content were correlated with the SO₂ removal efficiency. The produced absorbent exhibited high efficiency not only SO₂ but also for NO removal at temperatures ranging from 100-165⁰C of the gas mixture. NO serves as catalyst in the oxidation of SO₂ to SO, forming ettringite [Ca₆A1₂ (SO₁)₃(OH)₁₂25H₂O or 6CaOA1₂O₃3SO₃31H₂O) and CaSO₄ in the spent absorbent.