Study On The Reduction Mechanism Of The Pellets With Carbon Of Bayan Obo Iron Concentrate

The traditional blast furnace smelting process of Bayan Obo iron ore needs high energy consumption, carbon dioxide emissions are large, valuable elements can not be used effectively. In order to realize clean production and expand the use of natural gas, ecological gas (higher H2content) ratio, metallurgy workers dedicated to the development of direct reduction technology, such as the pre-reduction process of smelting reduction, the gas based sponge iron production processe, etc. But because the smelting temperature is lower, which makes the reduction rate of iron oxide is very slow. Therefore increasing the reduction rate of iron oxide is important for production.This paper mainly studied on the reduction mechanism of the pellets with carbon of Bayan Obo iron concentrate, inspecting the effects of catalyt(alkali metal carbonate K2CO3, Na2CO3, CaCO3)on the reduction process of the pellets with carbon.Using the method of weigheless process on Boudouard reduction, reduced Bayan Obo iron concentrate by CO gas and carbon in the experiment, then made use of ore phases、XRD、SEM analysis the mirostructure and phase composition of the sample which reducted.The results show that:the rate of gasification reaction and the reduction of iron concentrate were increased and the catalytic effect of K2CO3or Na2CO3is better than that of CaCO3after addition of the catalyst.The addition of the catalyst is helpful to improve the reactivity of carbon, then accelerates the Boudoeard reaction, thus promote the Bayan Obo iron concentrate of reduction reaction.Study the effects of carbon content (C/O) on the reduction process.Research shows that:under the same temperature, pellet reduction degree first increase then decrease as with carbon content (C/O is0.8-1.1) increase. Study the effects of coal and coke on the reduction process.Research shows that:at950℃, the C/O=0.9,adding the pellets containing carbon of the Liulin coal reduction degree is84.3%, the metallization was79.0%. Adding the pellets containing carbon of the coke reduction degree is73.1%, the metallization is63.95%, so it can be found under the same temperature and C/O, Liulin coal is much better than the reduction effect of coke.Study on the kinetics of carbon containing pellets of Bayan Obo iron concentrate by using TGA.By means of the C/O0.9,1.0,1.1at a temperature of1173K-1423K under the TG curve, then calculates the reaction fraction of carbon containing pellets, then according to the different expressions of velocity equation, calculated activation energy. Research results show that:(1) The interfacial reaction and the carbon gasification reaction is the speed limit link determined the activation energy is29.1-45KJ/mol.(2)Gas phase diffusion link is the speed limit links determined pellet containing carbon reduction activation energy is97.22KJ/mol, apparently carbon gasification reaction and interfacial’s activation energy is lower than that of the gas phase diffusion, thus reducing the speed of pellet containing carbon should be controlled by gas phase diffusion.