Suppressing SO 3 formation in copper smelting flue gas by ejecting pyrite into flue
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RESEARCH ARTICLE
Suppressing SO3 formation in copper smelting flue gas by ejecting pyrite into flue Qin Zhang 1,2 & Jiacheng Chen 2 & Yanan Wu 2 & Haipeng Liu 2 & Bin Gu 2 & Shen Hu 2 & Hongying Yang 1,2 Received: 7 November 2019 / Accepted: 9 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract SO3 in the copper smelting flue gas not only causes serious corrosion in heat exchange and dust collection equipment but also increases the amount of sewage acid (waste acid or polluted acid from copper smelting). In this study, we attempted to reduce the damage by ejecting pyrite into the flue to suppress SO3 formation in the flue. First, the Gibbs free energy for the chemical reactions between the substances was obtained after ejecting pyrite. Subsequently, the thermodynamic study of SO2–O2–H2O– N2–CO2–CO system was performed. Then, a kinetic study on the decomposition and oxidation behaviour of pyrite in the flue system was performed through thermogravimetric experiments. Results show that pyrite decomposition and oxidation in the flue system have a very strong oxygen consumption capacity. The SO3 formation in the copper smelting flue gas is suppressed by the consumption of oxygen in the flue to control the reaction direction of 2SO2 + O2 ⇋ 2SO3 and the partial pressure of SO3. Keywords Pyrite . Copper smelting . Flue gas . SO3 . SO2
Introduction Copper smelting flue gas contains many solid particles, SOx gas (SO, SO2, SO3 and other oxide forms of sulphur), arsenic, mercury, lead and other toxic components (Wu et al. 2019), which are main sources of air pollution. As environmental standards continue to rise, factories must treat copper smelting flue gas more stringently. The treatment process for copper smelting flue gas usually involves initial flue gas → waste heat recovery → dust collection → purification → SO2 conversion → sulphuric acid production → tail gas emission. The SOx in the initial flue gas is predominantly SO2, with a certain amount of SO3. The SO3 in the copper smelter flue gas Responsible editor: Philippe Garrigues * Qin Zhang [email protected] * Hongying Yang [email protected] 1
Key Laboratory for Ecological Metallurgy of Multi-metallic Mineral School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China
2
School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China
combines with water vapour to form sulphuric acid mist. When the flue gas temperature is lower than the acid dew point (ADP) (Xiang et al. 2016), the sulphuric acid condensed in waste heat boilers and dust collection systems causes severe corrosion of the equipment and increases the amount of waste acid generated in the purification process while reducing the work efficiency (Bahadori et al. 2011; Okkes 1987; Larson et al. 2000; Yan et al. 2010). The higher the SO3 concentration in the flue gas, the higher the ADP and the greater the damage caused. The SO3 formation sites in the copper smelting flue gas are scattered and the formation mechanism is complex. P
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