To effectively solve the problem of reutilizing semi-dry sintering flue gas desulfurized ash (SSFGDA) from steel plants, a new technology is proposed in this paper in which ash is added to a boiling furnace to obtain SO2 during sulfuric acid production. Using thermodynamics and simulation calculations, the high-temperature characteristics of CaSO3 in the ash were preliminarily investigated. By using Kissinger method and the models of Achar and Coats-Redfer, the decomposition kinetics equation of CaSO3 in the ash were obtained. The decomposition characteristics of CaSO3 in the ash were further investigated by thermogravimetric analysis (TGA) and drop tube furnace (DTF) experiments. The results show that at temperatures below 400 degrees C, free water is lost and Ca(OH)(2) decomposes, whereas at approximately 460 degrees C, part of the CaSO3 is oxidized. Above 680 degrees C, CaCO3 begins to decompose, with the decomposition process terminating at 790 degrees C. The remaining CaSO3 continues to decompose at approximately 810 degrees C. The activation energy of CaSO3 decomposition is 261.45 +/- 77.93 kJ/mol; the pre-exponential factor is expressed as ln(A/s (1)) = 26.13 +/- 7.29, and the kinetics equation is d alpha/dt = 2.19 x 10(11) x exp (-3.11 x 10(4)/T). Pressure, temperature and oxygen content are the key factors affecting the decomposition of CaSO3 in the ash. A lower pressure and oxygen content and a higher temperature can facilitate the decomposition of CaSO3 and can be achieved in actual sulfuric acid processing plants. Therefore, in this study, the feasibility of preparing SO2 by adding desulfurized ash during the production of sulfuric acid using a boiling furnace was preliminarily examined and verified. (C) 2017 Elsevier B.V. All rights reserved.