A critical review on the research progress of multi-pollutant collaborative control technologies of sintering flue gas in the iron and steel industry

The emission of flue gas in the iron and steel industry is high and contains a series of pollutants which that vary widely, especially in sintering process. With the depth of pollution control in China and the increasingly stringent emission standards, the flue gas pollutants of the steel industry require urgent management. At present, the sintering flue gas is mainly treated in the desulfurization and dust removal stages. Moreover, the measures for the management of nitrogen oxides and other pollutants have not yet been fully implemented in China's steel industry. Almost all the air pollution control techniques in the industry are aimed at single pollutant purification, where only few are targeted for multi-pollutant purification. Currently, the single pollutant treatment techniques can be divided into wet, semi-dry, and dry. Among them, the semi-dry and dry methods have gradually attracted much attention because of their high purification efficiency, compactness, and cost-effectiveness. Thus, they have become the main single pollutant treatment technologies for the sintering flue gas emission in the iron and steel industry. The present commonly used multi-pollutant removal technology is a single pollutant purification technique in series. With the increasingly stringent environmental standards in the steel industry, the original pollution control technologies and concepts have shown obvious deficiencies. This has seriously affected the development of China's iron and steel enterprises and smog management process. In addition, the tandem technology of single pollutant removal processes has the disadvantages of large area and high energy consumption. However, the simultaneous purification of multi-pollutants involves a simple process, short process flow, and low operation cost, and thus, it has become a research hotspot. Based on China's iron and steel industry sintering flue gas emission standards, emission characteristics, and current pollutant control technology, the technical ideas, characteristics and existing problems of multi-pollutant-coordinated control technology were analyzed, such as activated carbon adsorption process, LJS-FGD synergy pollutant purification process, MEROS technology, and a new type of dense semi-dry flue gas comprehensive management technology. Finally, some reasonable suggestions were presented for the development of multi-pollutants co-purification technology in the iron and steel industry.