Primary application of the "In-Bed-deNOx" process using Ca-Fe oxides in iron ore sintering machines

To decrease NOx emission from iron ore sintering machines inexpensively, a new process removing NOx within the sintering bed, named "In-bed-deNOx", wa s studied. This process utilizes the effect of Ca-Fe oxides, named CF, on N Ox elimination reaction. This report describes the reaction behavior of NO on mainly the CF liquid surface and the application study of "In-bed-deNOx" to actual sintering process. The effect of CF on the NO elimination reaction was investigated in the cru cible experiments. Reaction gas containing about 400 ppm NO was blown onto the specimen in reaction tube. The NO concentration in outlet was measured in the range of 800 degrees C to 1 400 degrees C, and 0.2 to 10(-17) mole f raction of oxygen. The CF, including ferrous oxide, shows the higher NOx el imination ratio. The NOx elimination ratio increases with increasing temper ature and decreasing oxygen potential. To verify the "In-bed-deNOx" process, some pot tests and experimental opera tions in the Kakogawa sintering plant were carried out. Firstly, the sinter ing pot tests were carried out by means of charging the CF pellets prepared in advance. NOx emission decreases with the increasing CF pellets addition . Secondly a sintering pot test was carried out by means of using limestone powder. NOx emission from the case of using limestone powder is as little as the case of charging CF pellets. An actual plant test was made by means of using fine limestone. Decreased NOx emission was achieved during the tes t period.