As is well known, mercury is one of the most hazardous elements for human health and earth environment. The "Minamata Convention on Mercury," which regulates Hg emissions, was enacted in 2016 by the United Nations Environment Program (UNEP). In Japan, Hg released in the ironmaking process accounts for about 40 % of total Hg emissions, and it originates mostly from the Hg element present in coal and iron ore. It is thus important to examine the dynamic behavior of Hg release during coal carbonization and iron ore sintering and to develop a novel technology of controlling Hg release. The main objective of this study is therefore to investigate the behavior of Hg release in the heating process of coal and iron ore in detail. Four kinds of coals and five types of iron ores were used in this study, and all experiments were carried out with a fixed bed quartz reactor. In a carbonization run, the dried coal sample was heated at 10 K/min up to 423-773 K in He flow, whereas, in the iron ore sintering, each ore was heated at 10 K/min up to 1223 K in air. Mercury contents of coal, semicoke and iron ore were measured by the combustion flask method and acid treatment/atomic absorption method. The gaseous mercury released was determined with a mercury analyzer. In the results of this study, the Hg present in coal was mostly released at low temperatures of ≤ 673 K during carbonization, whereas that in iron ore was emitted in the forms of Hg<sup>0</sup> and Hg<sup>2+</sup> during sintering, and the peak temperatures observed in the release profiles of these Hg species depended strongly on the type of iron ore.

Dynamic behavior of mercury release during coal carbonization and iron ore sintering

2019 Spring National Meeting

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