Production of SO₂ Gas: New and Efficient Utilization of Flue Gas Desulfurization Gypsum and Pyrite Resources

Abstract

To effectively solve the problem of recovery and utilization of flue gas desulfurized gypsum (FGDG), a new method for preparing SO2 gas by adding a mixture of FGDG and pyrite into a boiling furnace and utilizing its high-temperature waste heat is proposed. Using the FactSage 6.1 Reaction module and the Equilib module, the pyrolysis behavior of FGDG with pyrite and the release characteristics of SO2 gas were studied. The effects of FeS2 addition, temperature, and ventilation flow rate on the decomposition of FGDG and the change in gas behavior were studied by thermogravimetric mass spectrometry and settling furnace (SF) experiments. In addition, the activation energies of the chemical reactions were determined by the Kissinger method, the Kissinger–Akahira–Sunose method, and the Flynn–Wall–Ozawa method. The results show that between 100 and 200 °C, mainly the loss process of CaSO4·2H2O crystal water from FGDG occurred. At 570 °C, FeS2 primarily undergoes self-decomposition. Between 820 and 1000 °C, the decomposition product of FeS2 reductively decomposes CaSO4. The average activation energy for the chemical reaction is 298.44 ± 8.83 kJ/mol. A lower pressure and ventilation and a higher FeS2 addition and temperature are beneficial for the reduction and decomposition of FGDG and for the increase in SO2 concentration. Therefore, in this study, the feasibility of adding FeS2 to reduce and decompose FGDG to prepare SO2 was preliminarily verified. The technology proposed in this article may shed some light on the recovery and high-value utilization of FGDG.

Simultaneous Removal of SO2 and Hg0 by Composite Oxidant NaClO/NaClO2 in a Packed Tower

“…The dry CaSO 4 sludge that came from the product of WFGD has been widely used in the field of building materials. 39 …”

“…Normally, the solid products formed by the dehydration of CaSO 4 sludge would not be considered as hazardous wastes in China. The dry CaSO 4 sludge that came from the product of WFGD has been widely used in the field of building materials …”

Phosphogypsum Resource Utilization Based on Thermodynamic Analysis

“…FactSage is widely used in the field of scientific research and production [11][12][13][14][15]. The main function of FactSage software is the simulation of thermodynamic parameters for various chemical reactions, determination of chemical reaction equilibrium, and plotting of phase diagrams [16][17][18][19]. For thermal decomposition of phosphogypsum, it is essential to evaluate its decomposition conditions and mechanisms of these processes [13,20].…”

“…For thermal decomposition of phosphogypsum, it is essential to evaluate its decomposition conditions and mechanisms of these processes [13,20]. The application of FactSage is very important in developing and analyzing the reaction conditions and mechanisms of these processes for phosphogypsum resource utilization [19].…”

Calcium Sulfite Solids Activated by Iron for Enhancing As(III) Oxidation in Water

“…The wet desulfurization process has significant advantages of fast reaction and high efficiency, and has been widely used in China. However, desulfurized gypsum (DG) cannot be fully utilized, and its disposal constitutes a waste of resources [ 1 , 2 ]. Currently, DG is mainly used as a soil conditioner [ 3 ], serving to improve certain properties of soil, such as its pH, water absorption, water retention, and so on.…”