Influence of Gangue Species on Hydrogen Reduction Rate of Liquid Wustite in Gas-conveyed Systems.

Abstract

A laboratory scale fine particles-gas conveyed system was utilized to measure the hydrogen reduction rates of liquid wustite containing gangue such as 14.5 mol%CaO, 18.2 mol%SiO2, or 5.15 mol%A2O3 at 1773 K. The N2-H2 mixture having various flow rates and compositions was flowed downward through a cylindrical reactor maintained isothermally and a batch of spherical wustite particles (mean dia.; 58 μm) was concurrently fed into the reactor at a small constant rate and reduced in a hot zone. The reduction process was found to proceed in such a manner that a single metallic iron sphere was formed in the center of a wustite droplet. Rate analysis was made according to one dimensional mass balance equations for particles and gas in an isothermal steady moving bed. Under relatively small reducing potentials, it was concluded that the major fraction of overall reaction resistance is attributable to chemical reaction. The obtained chemical reaction parameters were found to be two orders of magnitudes larger than those in previous CO reduction. CaO raised the parameter, SiO2 lowered it, and Al2O3 did not affect it, relative to gangue-free one. Under higher reducing potentials, the reduction process was estimated to include an appreciable diffusion resistance in the liquid particle.