Division Applicability of the SCR process under BAT II.ii

SCR can be applied within a high dust system, a low dust system and as a clean gas system. Until now, only clean gas systems (after dedusting and desulphurisation) have been applied at sinter plants. It is essential that the gas is low in dust (< 40 mg dust/Nm³) and heavy metals, because they can make the surface of the catalyst ineffective. Additionally, desulphurisation prior to the catalyst might be required. Another prerequisite is a minimum off-gas temperature of about 300 °C. This requires an energy input.

The high investment and operational costs, the need for catalyst revitalisation, NH₃ consumption and slip, the accumulation of explosive ammonium nitrate (NH₄NO₃), the formation of corrosive SO₃ and the additional energy required for reheating which can reduce the possibilities for recovery of sensible heat from the sinter process, all may constrain the applicability. This technique might be an option where environmental quality standards are unlikely to be met through the application of other techniques.