Utilization of Simulated Coal Gases for Reducing Iron Oxide Pellets

摘要

The Bureau of Mines is investigating the use of complex gas mixtures, such as would be produced by coal gasification, for reducing iron oxide pellets. A semiempirical model was developed to predict a priori the reduction rate of an iron oxide pellet in a laboratory tube furnace with simulated coal gases at a total pressure of 1 atm. The model uses partial pressures of H2, CO, CO2, CH4 (methane), water vapor, and a temperature-dependent term to predict the rate of reaction. The reduction rate (weight loss per unit of time) was determined with a thermogravimetric apparatus (TGA) in the temperature range of 800 to 1,100 C. The ranking of the reductants, in order of decreasing reducing potential, is H2, CO, and CH4 at temperatures between 800 and 1,000 C; however, CH4 became a better reductant than CO at 1,100 C. Water vapor did not decrease the reduction rate as much as did CO2. Carbon deposition was observed at temperatures below 1,000 C with gas mixtures with high CO and low H2 concentrations.