Enhancing SO2 removal efficiency by lime modified with sewage sludge in a novel integrated desulfurization process

In China, the sintering process annually emitted around 1.5 million t SO₂, representing 70% of SO₂ produced from the iron and steel industry. Lime based sorbent was modified with municipal sewage sludge (MSS) and the influence of the modification on the desulfurization efficiency was investigated in a laboratory-scale novel integrated desulfurization (NID) reactor. The properties of modified sorbent were characterized by the Brunauer–Emmett–Teller (BET) analyzer and X-ray fluorescence (XRD) analyzer. BET surface area was increased from 17.48 to 46.68 m²g^–1. when the MSS/lime ratio increased from 0 to 0.08. Ca₄Al₈Si₈O₃₂, Ca_1.5SiO_3.5, Na₂Si₂O₅ and CaSiO₃ found in the modified lime benefited for the increase of the BET surface area and pore volume. The effects of sewage sludge/CaO weight ratio, calcination temperature and hydration time on the desulfurization efficiency were also studied. SO₂ removal efficiency was increased from 88.7% to 97.3% after using the lime modified with sewage sludge.