Oxidation modification of semi-dry desulfurization ash from sintering flue gas

The semi-dry desulfurization ash obtained from sintering flue gas contains a large amount of CaSO₃, which has an important stabilizing influence on desulfurization ash, and thereby restricts its disposal and comprehensive utilization. In order to solve this problem, low-temperature static oxidation and high-temperature dynamic roasting were adopted for studying desulfurization ash oxidation modification in the presence and absence of catalyst, respectively. Besides, the high-temperature dynamic oxidation of CaSO₃ in semi-dry desulfurization ash was studied using thermogravimetry (TG). The results showed that the catalytic effect decreased in the order MnO₂>Fe₂O₃> catalyst-free>V₂O₅ in the oxidation modification experiments performed for 2 h at reaction temperatures of 45, 75, and 90℃; the oxidation rates of CaSO₃ under all these conditions were less than 2.2%. When the roast temperature was maintained above 350℃ without catalyst for 30 min to 60 min, the oxidation rate of CaSO₃ could exceed 85%. Besides, the TG results showed that the appropriate roasting temperature and roasting time played an important role in improving the oxidation rate of CaSO₃ in semi-dry desulfurization ash.