Carbochlorination Reduction of Ilmenite (FeTiOa)
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Date
2008
Authors
Astrawinata, Rizal
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Abstract
Thermogravimetric analysis (TGA) has been proven to be an effective tool in the studies
of carbochlorination kinetics ofoxide minerals. Using this technique effects of the reaction
parameters, such as gas flow rate, temperature and partial pressure of the carbochlorinating
gas mixture on the rate of reaction have been examined by earlier investigators.
Experimental results indicated that the rate ofreaction, in some instances, increases as the
carbon mass fraction increases.
Particulad)' for v:.daes of metallic titanium, e.g., ilmenite (FeTi03) and rutile (Ti02), the
chlorination ofmetallic oxide in the presence of carbon (carbochlorination) has displayed
the potential to set off two or more'consecutive reaction stages as indicated by the different
activation energy values for each reaction stage.
In this research investigation, which was financed by the short-term grant,
unfortunately, the intended carbochlorination experimentation could not be carried out
because the limited budget was not enough to provide an experimental rig which abides the
safety & health regulation on the usage of toxic chlorine gas. Without the hazardous gas
monitoring and safety devices, however, the experimental rig can and has been utilized to
conduct thermogravimetric analysis (TGA) using non-toxic gases, such as : air, oxygen,
nitrogen, etc.
The objective of the investigation that has been carried out with the existing
experimental rig was to study the reaction mechanism of titanium aluminides in air and in
nitrogen gas environment at high temperatures. Although this alloy has superior hightemperature
mechanical properties, its high-temperature application is limited by its
relatively poor resistance against hot gases.
As the outcome of this study, the experimentally obtained activation energies of the
scale formation reaction on the surface ofTi-48AI-2Cr-2Nb alloy exposed in air and in
nitrogen gas are 277.5 kllmol and 224.8 kllmol, respectively. The obtained result is in
accord with the quantitative observation of scale thickness on the surface of the alloy which
is thicker in nitrogen gas than in air. At higher temperatures, the rate of growth and hence
the scale thickness will increase. The scale formation on the surface of the alloy may
eventually limit the alloy's service life-time.
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Materials and Mineral Resources Engineering