MECHANISM OF IRON OXIDE REDUCTION WITH HYDROGEN/CARBON MONOXIDE MIXTURES.

Abstract

Pure iron oxide briquettes, differing in grain size and porosity and hardened at different temperatures, were reduced with H//2, CO, and mixtures of both gases at 800 to 1000 C. The reduction mechanism was found to depend mainly on the original structure of the briquette and the reducing gas composition. Reduction of dense briquettes with H//2 is controlled by chemical reaction; reduction with CO or CO/H//2 mixtures is controlled by both chemical reaction and gaseous diffusion. Reduction of porous briquettes is diffusion controlled for all gases. Rate minima for porous briquettes were detected at 975 degree C for CO reduction at 1,025 degree C for CO/H//2 mixtures. The overall reduction rate varied exponentially with gas composition.