Residues from single-stage dry de-dusting and desulphurization of sinter plant off-gas: enabling partial recirculation by classification.
C. Lanzerstorfer, R. Neuhold - Residues from single-stage dry de-dusting and desulphurization of sinter plant off-gas: enabling partial recirculation by classification. - INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY, Vol. 12, No. 9, 2015, pp. 2939-2946
In iron ore sinter plants the process off-gas is de-dusted by electrostatic precipitators which are installed upstream of the fan. For further reduction of emissions a second cleaning stage can be installed. This stage usually comprises a sorption process for removal of acid gases and polychlorinated dibenzo(p)dioxins and furans, followed by a fabric filter. The residue from the first de-dusting stage can be re-circulated to the sinter process. The residue from the second cleaning stage has to be disposed of in landfill sites. A new single-stage off-gas cleaning concept for sinter plants comprises an entrained flow sorption process and a fabric filter, installed upstream of the fan. In this way, the investment costs for the off-gas cleaning system can be reduced significantly. However, it would become necessary to dispose of most of the residue. In this work, air classification of a residue equivalent to that of a single-stage off-gas cleaning unit was investigated with the aim of producing a fraction of this residue with reduced sulphur and chloride concentrations which can then be recycled. The results confirm that classification is a suitable process. In case of chlorine limitation it was possible to increase the recycling rate for the dust from 42% to 66% assuming the chlorine limit at the current recycling rate of chlorine caused by the recycling of the electrostatic precipitator dust.