Experimental research on the novel process of iron ore direct reduction by coal gas

摘要

In this paper, the direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and Hyl III process, the influence of gas composition and temperature on reduction was studied. Results show that the proportion of H_2 increasing is helpful to improve the reduction rate, while when H_2/CO>1.6, changes of H_2 content will have very little influence on it. Appropriate reduction temperature is about 950°C, higher temperature(1000°C) may unfavorably slowed the reduction rate. From the kinetics analysis at 950°C and 1000°C, when H_2/CO=0.4 the prophase of reduction course (～90%) is likely controlled by interfacial chemical reaction mechanism and in the later controlled by gaseous diffusion mechanisms. However, when H_2/CO>0.4 the whole reduction course is likely controlled by interfacial chemical reaction mechanism. The reaction rate constant (k) and effective diffusion coefficient (De) at 950°C are both better than those at 1000°C. Research also shows that the coal-water slurry gasification based on Texaco furnace is more suitable for iron ore direct reduction than other coal gasification processes.