New insight into investigation of reduction of desulfurization ash by pyrite for clean generation SO2

Desulfurization ash (DA) has become one of the major industrial solid wastes and is a factor in multiple environmental problems. In order to effectively solve the problem of the reuse of DA, a new technology is proposed in this paper in which DA containing pyrite (compound DA) is added to fluidized bed furnaces to produce SO₂ gas. This gas can be used as the raw material for sulfuric acid production, which not only reduces the consumption of natural resources, but also brings economic and ecological benefits to solid waste management. Our study concerns the high temperature decomposition behavior of compound DA, which was studied using FactSage 6.1 software. The high temperature decomposition characteristics and gas release characteristics of compound DA were further studied using thermogravimetric mass spectrometry (TG-MS) experiments, and the kinetic characteristics of the resulting chemical reactions were calculated. Finally, the effects of reaction temperatures and ventilation rates on SO₂ concentration were analyzed by simulating industrial fluidized bed furnaces, and the feasibility of the proposed technology was verified. Our results show that the addition of FeS₂ causes DA to decompose ahead of time, and also increased the concentration of SO₂ significantly. The decomposition of compound DA has a smaller activation energy value, which is conducive to the reduction of energy consumption and reaction rates. When the average SO₂ content was increased from 1371.82 ppm to 2090.16 ppm, the ventilation volume increased from 1 L min⁻¹ to 5 L min⁻¹, and the average SO₂ content decreased from 1474.37 ppm to 1223.57 ppm. These results show that higher temperatures and lower ventilation can increase SO₂ concentration. Therefore, utilizing pyrite and DA to produce clean SO₂ gas is a promising and value-added waste management method.