Effect of inlet gas composition on dioxins emission in the iron ore sintering process

The various factors of solid in raw materials have been pointed out for dioxin emissions from iron ore sintering process. It has been reported that copper and its components are catalysts and that ammonia and nitrogen-bearing organic compounds are inhibitors for dioxins formation. And it has been also reported that coke, which is the major fuel in the iron ore sintering process, gives the higher emissions than other carbonaceous materials, e.g., anthracite, coal, activated coke and coal. In addition, fundamental studies have indicated that the dioxin is considered to form with oxidation reaction of residual carbon particles formed by the solid fuels in the sintering process. So, inlet gas composition affects the oxidation reaction and dioxins formation. The main result is that increasing H2O concentration by injecting steam into inlet gas results in decreasing dioxin emission. This result suggests that H2O has a role of inhibiting residual carbon particles formation by promoting CO oxidation reaction to CO2, The phenomenon of promoting CO oxidation reaction was confirmed by exhaust gas analysis. The other main result is that decreasing O-2 concentration to 17 vol% by injecting N-2 gas into inlet gas also results in decreasing dioxin emission. This results suggests decreasing O-2 concentration to 17 vol% is effective to inhibit the oxidation reaction of residual carbon particles without promoting residual carbon particles formation.