In-Situ Study of Gaseous Reduction of Magnetite Doped with Alumina Using High-Temperature XRD Analysis

Abstract

The reduction of magnetite of technical grade and magnetite doped with 3 mass pct Al 2 O 3 was studied in situ using high-temperature XRD (HT-XRD) analysis. Magnetite was reduced by CO-CO 2 gas (80 vol pct CO) at 1023 K (750°C). Reduction of magnetite doped with alumina occurred from the Fe 3 O 4 -FeAl 2 O 4 solid solution which has a miscibility gap with critical temperature of 1133 K (860°C). The degree of reduction of magnetite was derived using Rietveld refinement of the HT-XRD spectra; the compositions of the Fe 3 O 4 -FeAl 2 O 4 solid solution and the concentrations of carbon in c-iron were determined from the lattice constants of the solutions. The reduction of magnetite progressed topochemically with the formation of a dense iron shell. The reduction of alumina-containing magnetite started along certain lattice planes with the formation of a network-like structure. Reduction of alumina-containing magnetite was faster than that of un-doped magnetite; this difference was attributed to the formation of the network-like structure. Hercynite content in the Fe 3 O 4 -FeAl 2 O 4 solid solution in the process of reduction of magnetite doped with 3 mass pct Al 2 O 3 increased from 5.11 to 20 mass pct, which is close to the miscibility gap at 1023 K (750°C). The concentration of carbon in c-Fe (0.76 mass pct) formed in the reduced sample of magnetite doped with 3 mass pct Al 2 O 3 was close to the equilibrium value with 80 vol pct CO to 20 vol pct CO 2 gas used in the HT-XRD experiments.

Phosphate removal using aluminum-doped magnetic nanoparticles

“…The lattice constant of the doped Fe 3 O 4 -FeAl 2 O 4 solid solution as a function of FeAl 2 O 4 concentration X (mol%) at room temperature was described by the following Vegard's equation [27]:…”

Pyro-Metallurgical Processing of Ilmenite Concentrate with Production of Iron and Titanium Oxides

“…The prereduction is carried not only during processing of iron [1][2][3], but also chromium [4][5][6][7], manganese [8][9], as well as titanomagnetite and ilmenite ores [10][11][12][13][14].…”

Pore morphology evolution and atom distribution of doped Fe2O3 foams developed by freeze-casting after redox cycling

“…At 750 ºC, Mss shows a solubility maximum of 12 wt.%. The use of up to 3 wt% Al2O3, enhances the reduction process of Fe3O4 due to the formation of a network-like structure of wüstite [23,24].…”