Desulfurization and denitration of sintering flue gas by blast furnace process

The technical feasibility of desulfurization, denitration and dioxin removal from sintering flue gas processed by blast furnace was discussed in theory. The reduction thermodynamics of sulfur dioxide and nitrogen oxides as well as the conditions for dioxin decomposition in a blast furnace were analyzed. The effects of blast with sintering flue gas instead of air on the theoretical flame temperature (TFT), blast volume, gas in hearth, top gas and sulfur content of hot metal were investigated. The results show that sulfur dioxide and nitrogen oxides can be reduced in the BF interior, and the lowest equilibrium volume fractions of sulfur dioxide, nitric oxide and nitrogen dioxide are 1.84×10-13%, 3.08×10-11% and 3.72×10-21%, respectively. Favorable thermodynamic conditions for dioxin decomposition are found in the blast furnace. Sulfur dioxide and carbon monoxide in sintering flue gas have little effect on the TFT, while nitrogen oxides can slightly increase the TFT. The TFT decreases by about 40.5% with a 1% increase in carbon dioxide volume fraction of sintering flue gas, but the thermal state of a hearth can be improved to the normal level by reducing the humidity and increasing the oxygen enrichment of blast. The blast volume, gas in hearth and top gas decrease with increasing carbon dioxide content of sintering flue gas. As the carbon dioxide content of sintering flue gas rises, the carbon monoxide and hydrogen contents of gas in hearth and the carbon monoxide, hydrogen, carbon dioxide and water contents of top gas increase, but the nitrogen contents of gas in hearth and top gas decrease. The sulfur quality content of hot metal is proportional to the sulfur dioxide content of flue gas and it is raised to 0.025% when the sulfur dioxide content increases to 2000 mg·m-3. The BF production can proceed smoothly with sintering flue gas blast instead of air through comprehensive operating measures, achieving the purpose of desulfurization, denitration and dioxin removal.