Research On Reducing Iron Ore By Coke Oven Gas Auto-reforming

With the proportion of electric furnace steelmaking on the steel production increasing, the demand for direct reduced iron increases accordingly. It can not only reduce harmful impurities from scrap steel, but also imrove the quality of smelting steel by using direct reduced iron as raw materials. The proportion of gas based direct reduced accounting for direct reduced iron achieved 80%. It has become the important topic of the direct reduction technology research. As outgrowth of coking industry, the composition of coke oven gas contains hydrogen from 45% to 55% and methane from 20% to 24%. A large number of coke oven gas has not got rational utilization with the development of coke industry. It can occur auto-reforming reduction reaction making the methane reforming for carbon monoxide and hydrogen and reducing the iron ore effectively by pumping into the shaft furnace.It was concluded that the influence of temperature, pressure, ferrous oxide and gas composition of coke oven gas on each composition after reduction and got the feasibility analysis of coke oven gas reducing iron ore by utilizing chemical reaction balance and material balance equation. The coke oven gas auto-reforming effect and proposed reaction pathway on the metal iron was calculated by the bond order conservation theory combing the experimental research on metal surface reaction mechanism. The auto-reforming reaction rate and water vapour and carbon dioxide reforming activation energy was calculated under different coke oven gas compositions by using dynamic calculation method. It was concluded that the characteristics of coke oven gas auto-reforming reducing iron ore analyzing the change regularity of various components, the reaction rate and temperature into the shaft furnace height direction by the three interface reactor model combining with the mass conservation equation. The results show that:(1) More hydrogen reacted with carbon dioxide to produce water and carbon monoxide with temperature rising; The impact ofreaction pressure on the auto-reforming was little; Carburization quantity was less than 3%while coke oven gas auto- reforming reducediron ore.(2) It generated CHO and CO by CO2 reacting with CH under the reforming process. Carbon generated CH from iron surface reacting with OH or H2 O. CHx could crack independently or react in the form of CHx O.(3) The reorganization rate reached 24% while the temperature was 1273 K by charging coke oven gas auto-reformingon the sponge iron catalyst; Reorganization rate reached 73% at the same temperature from middle-lower partcoke oven gas reforming as the furnace gas continued to rise;Reorganization rate reached 75% from upper partcoke oven gas auto-reformingwhile the temperature was 1273 K.(4) The reaction rate equation of coke oven gas auto-reforming inthesponge iron catalyst is:(5) The content of methane and hydrogen reduced gradually with water and carbon monoxide and carbon dioxide increasing.The gas comprehensive utilization rate achieved 43.12%. The metallization rate of iron ore in the shaft furnace reached 92.31%.