18 - Sintering emissions and their mitigation technologies

Abstract

Waste gases from iron ore fine preparations for blast furnace ironmaking, or sintering, contain minute quantities of acidic species, dust, and dioxin pollutants, but because of the very large quantities of iron ore processed and the large volume throughput of air involved, sintering is a major source of these emissions and also CO2 into the atmosphere. Sintering plants rank second in terms of toxic emissions after the incineration of municipal solid waste and contribute of the order of 10% of the total CO2 emissions generated during the production of iron and steel. As legislated limits become increasingly more stringent, sinter plants are under scrutiny by local authorities to further decrease emission levels. Extensive efforts have been made in mitigating CO2 and toxic emissions from sinter plants since 1980–1990 and a number of different technologies are now available. However, most of these technologies are secondary measures that take effect only after emissions are formed, adding to the complexity of the operations. To improve the understanding of changes in steelmaking operations in East Asia, CSIRO in conjunction with the Fortescue Metal Group Ltd has evaluated different technologies for the mitigation of pollutants from sinter plants. This chapter will first examine the emission characteristics of CO2 and various toxic species, including SOx, NOx, dioxins, and particulate matter and then discuss available technologies for preventing and reducing the formation of these toxic species from the sintering bed.