Influence of a Prior Oxidation on the Reduction Behavior of Magnetite Iron Ore Ultra-Fines Using Hydrogen

Abstract The reduction behavior of raw and prior-oxidized magnetite iron ore ultra-fines with hydrogen was investigated. Reduction tests were conducted a thermogravimetric analyzer in temperature range from 873 K to 1098 at 1.1 bar absolute, using as reducing gas. experimental results show that prior oxidation the has positive effect on because changing morphology. apparent activation energies turnaround negative values, depending degree reduction. A multi-step kinetic analysis based model developed by Johnson–Mehl–Avrami used reveal limiting mechanism during At 948 K, initial stage is controlled nucleation chemical reaction final only, for both pre-oxidized magnetites. higher temperatures, 1023 mainly diffusion. This changes mixed stage. Processing hydrogen-based direct technology, lower temperatures are recommended, whereby high not necessary.