Transcript Cadogan_Iron ore processing.ppt

Quantitative analysis of
iron ore processing
J.M. Cadogan
Department of Physics and Astronomy
University of Manitoba
Winnipeg, Manitoba, R3T 2N2
Canada
E-mail: [email protected]
Direct Reduction
There are a number of promising emerging technologies in the World’s
steel production industry. Their advantages over traditional blast-furnace
production are:
• Lower overall investment and production costs
• The avoidance of certain processing steps
• Iron ore ‘fines’ can be used
• Reducing environmental impact
• One such alternative is Direct Reduction whereby iron ore is reduced to
metallic iron below the melting temperatures of the constituent materials.
(DR was actually known in ancient times !)
• We have studied the Direct Reduction of Australian iron ore by heating the
ore in hydrogen at either 600 oC or 800 oC.
•
57Fe
Mössbauer Spectroscopy allows one to follow the evolution of the Febearing phases as a function of such parameters as reduction time.
Starting material
(mainly Haematite
Fe2O3 with traces
of non-magnetic
Wüstite Fe~0.95O)
Finished product
(mainly a-Fe with
a trace of
Magnetite Fe3O4)
All 57Fe Mössbauer spectra shown here were obtained at RT
Transformation of iron ore to iron at 600 oC:
Processing time
57Fe
Mössbauer spectroscopy allows us to follow the
kinetics of the transformation from iron ore (Haematite
[Fe2O3], Magnetite [Fe3O4] and non-magnetic Wüstite
([Fe~0.95O]) to iron (α-Fe).
• Mössbauer spectroscopy is ideally suited to monitoring the transformation of
iron ore to iron
• Quantitative analysis of the various Fe-bearing phases present can be obtained,
although assumptions with regard to parameters such as the f-factors of the
various phases involved may be needed.
• Reduction of Fe2O3 is quite rapid compared to that of Fe3O4 and FeO (Fe2O3
has virtually disappeared from the iron ore sample reduced in hydrogen at 800
oC for 30 seconds !)
• The extrapolation of the a-Fe content to zero wt% does not pass through the
origin (t = 0). This may reflect an activation time for the full transformation of
Fe2O3 into Fe3O4 and FeO, prior to the gradual final transformation to a-Fe.
References
A. Zhou, M.Sc. Thesis, University of NSW, Sydney, Australia (1998)
V. Sahajwalla, J.M. Cadogan and A. Zhou, AusIMM Annual Conf. (1996) pp 267-272
A. Zhou, K. Suzuki, V. Sahajwalla and J.M. Cadogan, Scand. J. Metallurgy 28, 65-9 (1999)