| Mercury pollution is a current concern of global environmental issues. Nonferrous metal smelting is not only the dominant mercury emission source, but also the key control source in the Minamata Convention on Mercury. However, the mercury emission characteristics as well as the emission inventory are subject to high uncertainty. Therefore, the study of the mercury emission characteristics and the update of the mercury emission inventory of China’s nonferrous metal smelting industry are of vast importance for China’s mercury pollution control and for the implement of the international mercury treaty.This study has sampled nonferrous metal concentrates nationwide and analyzed mercury concentration in the concentrates. Combining the literature research, a database of mercury concentration in China’s nonferrous ore concentrates is established. Field experiments on mercury emission characteristics during both the metal production and waste disposal processes of the nonferrous metal smelting industries have been carried out, so as to analyze the mercury input, the mercury transformation in the flue gas and the mercury emission characteristics to the environment. On this basis, a material–technology–based mercury emission model was constructed to calculate the mercury emission of China’s nonferrous metal smelting industries. Further, the reduction potential of mercury emission of nonferrous metal smelting industries was predicted by using scenario analysis method and the control strategies were put forward.The results indicated that the best estimated concentration of China’s consumed zinc, lead and copper concentrates were 77.5, 31.4 and 5.8 μg/g, respectively. Approximately 98.3–99.4% of mercury in the concentrates was released into the roasting/smelting flue gas. Most mercury in the flue gas was captured by the air pollution control devices. The atmospheric mercury emission from metal production process only accounted for 0.1–11.6% of the total mercury input. The mean mercury removal efficiency of the dust collectors(WHB+CYC+ESP), flue gas purification system(FGS+ESD), acid plants with single contact and single absorption towers(APS), acid plants with double contact and double absorption towers(APD), and wet flue gas desulfurization system(WFGD) was 17.0, 82.5, 55.4, 82.1, and 52.0%, respectively. Hg2+ was the dominant species after APD. During the waste disposal process, mercury in the waste acid was accumulated in the sludge. Mercury in the sulfuric acid for fertilizer production was mainly released to the fertilizer and phosphogypsum. Mercury in the leaching slag and extraction slag was mainly emitted to air as Hg0. The mercury emission to air, water and soil was 158.3, 45.1 and 12.3 t, respectively, in 2012. The percentage of Hg2+, Hg0 and Hgp in the exhaust gas was 36.2, 62.1 and 1.7%, respectively. Compared to the emission in 2012, mercury emission to air, water and soil could be reduced by as large as 130.0, 38.3 and 9.6 t, respectively, in 2030. In the future, the atmospheric mercury emissions of nonferrous metal smelting industry could be reduced by readjusting industrial structure, strengthening acid making and flue gas desulfurization, and installing specific mercury removal devices. |
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