Emission characteristics of PM, heavy metals, and dioxins in flue gases from sintering machines with wet and semi-dry fl
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ENVIRONMENTAL CONCERNS AND POLLUTION CONTROL IN THE CONTEXT OF DEVELOPING COUNTRIES
Emission characteristics of PM, heavy metals, and dioxins in flue gases from sintering machines with wet and semi-dry flue gas desulfurization systems Hui Wang 1,2,3 & Pu Zhang 1,2,3 Received: 4 August 2020 / Accepted: 2 November 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In iron and steel industry, sintering process releases large amount and different kinds of pollutants. Most sintering plants had applied the dust removal system and the flue gas desulfurization (FGD) system for exhaust treatment in China. Previous studies of FGD systems were focused on the removal of air pollutants from coal-fired boiler, rather than in the iron ore sintering process. In this study, PM, heavy metals, and dioxins were sampled at a China typical sintering plant with both wet and semi-dry FGDs. The results showed that the PM removal efficiencies of the wet and semi-dry FGDs were 29.44% and 22.28%, respectively. The size distributions of PM were at the range of 0.7~4.7 μm in the inlet flue gases of both FGDs. The overall removal efficiencies of heavy metals were above 65%. In both outlet flue gases, Pb as the most elements accounted for 93.33% of total at the wet FGD, while Pb, Cr, and Zn accounted for 76.34% at the semi-dry FGD. The proportions of gaseous heavy metals in the inlets of both FGDs were improved than those in the outlets. Furthermore, the total emission amounts of dioxins in both inlets and outlets of the flue gases were 0.0385 ng-TEQ/m3 and 0.0248 ng-TEQ/m3 at the wet FGD and 0.0078 ng-TEQ/m3 and 0.0050 ng-TEQ/m3 at the semi-dry FGD, respectively. The overall removal efficiencies of dioxins were all above 35%. The polychlorinated dibenzofurans (PCDFs) ratio in the dioxins lightly increased from 84.46 to 88.80% through wet FGD, while it decreased from 80.83 to 44.35% in semi-dry FGD. Keywords Sintering flue gas . FGD . PM . Heavy metal . Dioxin
Introduction The sintering process is to make mineral powder block. Mineral powder, which is made of limestone, lime, crushed coke, anthracite, and other raw materials, is burnt in 1300~1500 °C from top to bottom under negative pressure in sintering machine. This process releases amount of flue gases which contains amount of pollutants such as PM, SO2, NOX, Responsible Editor: Philippe Garrigues * Hui Wang [email protected] 1
Central Research Institute of Building and Construction Co., Ltd, MCC Group, Beijing 100088, China
2
State Key Laboratory of Iron and Steel Industry Environmental Protection, Beijing 100088, China
3
Energy Conservation and Environment Protection Co., Ltd, MCC Group, Beijing 100088, China
heavy metals and dioxins, etc. These pollutants produced by the sintering process are harmful and complex (Annamalai et al. 2016; Yu et al. 2017; Zhong et al. 2017). China has the most iron and steel production all over the world from 1996 (Wang et al. 2007). The emission of PM, SO2, NOX, and dioxins in sintering flue gas accounted for about 20%, 60%, 5
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