Abstract
The effect of phosphorus vapor on the reduction process of iron oxide with CO-N2 or CO-CO2 gas mixtures was measured by thermobalance. It was found that the rate of reduction increased with increasing partial pressure of phosphorus vapor in reducing gas. However, the apparent reduction rate decreased above a partial pressure of phosphorus vapor of 10-3 atm. Then, by using the wustite pellet exposed in P-N2 atmosphere before reduction, the reduction rate was measured at 900°C. The reduction rate was observed to be accelerated by absorbed phosphorus.
On the other hand, it was found from the microstructural observation of reduced pellet that the size of pores and the number of large open pores in the reduced pellet increased with adding the phosphorus vapor to reducing gas or exposing the pellet in P-N2 gas. Accordingly, it was considered that the resistance for mass transfer in the gas phase through the pores in the reduced iron layer decreased with the addition of phosphorus vapor, resulting in the increase in the reduction rate of iron oxide pellet.
