Iron Ore Reduction and Iron Carburisation by H_2-CH_4-Ar Gas Mixtures

摘要

Iron carbide process occurs in two consecutive steps of iron ore reduction and carburisation. Iron ore is mainly reduced by hydrogen. The reduction rate increases with increasing temperature and increasing hydrogen contents in the gas phase. However when hydrogen content is more than 55 vol%, this increase is not significant. Methane has a slight effect on the reduction process. The critical gas flowrate for independent gas flow regime was found to be 1000 cm~3/min under experimental conditions employed in this work. The rate of reduction increases with decreasing ore size from 1-2mm to 0.212-0.355mm, and decreases further with decrease in size. Iron carburisation rate also increases with increasing temperature. However high temperature causes methane cracking and carbon deposition. The optimal temperature for cementite formation is 750℃ and cementite is the most stable at this temperature. Methane and hydrogen content in the gas phase should be above 35 vol% each. The rate of cementite decomposition increases with increasing temperature from 500 to 600℃, decreases with increase in temperature from 600℃ to about 750℃ and increases with increasing temperature above 750℃.