Study On Reductive Characteristic And The Behavior Of Carbon During Producing Sponge Iron In Shaft Furnace

The sponge iron could replace scrap as the staple of the EAF,especially high-quality steel could be made by EAF.Due to lack of scrap,sponge iron becomes more and more important as it can replace scarp. In this text,it describes some results including reduction time as well as the behaviors of carbon,which provide a reference for the actual production.Iron content is a quality index for sponge iron,well reduction time has direct impact on productivity.At the base of studying conditions of different process,experiments have been carried out using the complete set of metallurgical capability test of sinter or pellets,which designed ourselves.The content of CO+H₂ is about 90% and the ratio of H₂/CO is different to change the conditions.Gas flow is 0.3 m3/h.Temperature is controlled in accordance with our wishes and pellets come from Chongqing Steel The experimental results indicate that as long as reduction time reaches 5.5 hours the iron content would come up to 92% no matter what proportion between H₂ and CO in the reducing gas we used.The reaction rate will be faster when the ratio of H₂ increases.When CO₂ is added to the gas reduction time has prolong to 6.5 hours if we want to get qualified sponge iron.Then we integrate theory with practice and establish mathematical model for reaction rate under certain conditions.In shaft furnace,CO—CO₂ has the character of carburization and the carbon granules have smalle size as well as high activity so they can come into firebrick lining and destroy it easily. Thus we need do some work on the behaviors of corbon to find efficiency ways which can control adverse effects.Through experimental results we find that there is more powder produced when temperature is around 500℃.As the reduction experiments completed,we weigh the mass of carbon granules and then we can find out the influences of the gas on the mass of carbon powder. In addition,we use Al₂O₃ balls instead of pellets carrying out the reduction experiments to study catalysis of iron for the reaction.The results indicate that iron has obviously catalysis for the reaction.On the other side, we test the content of C in metal pellets,and find that under the laboratory conditions,carbon condition in sponge iron is between 0.5%～1.1%.