A dissertation submitted to the Faculty of Engineering,
University of Witwatersrand, Johannesburg, in fulfilment of
the requirements for the degree of Master of Science in
Engineering
Johannesburg, 1991 / The kinetics of reduction of the manganese ore from the
Mamatwan mine has been studied by thermogravimetric
(TGA) analysis, x-ray diffraction analysis (XRD),
optical microscopy, and energy dispersive analysis of
x-rays (EDAX) between 1100 and 1350 degree celcius with pure
graphite under argon atmosphere. It has been observed
that the rate and degree of reduction increased with
increasing temperature and decreasing particle size.
The effect of the different reaction atmosphere has
also been investigated by replacing argon atmosphere
with carbonmonoxide (CO) and carbondioxide (C02)' The
results clarified importance of some reactions in the
reduction mechanism of the ore.
In early stages of reduction, up to about 4 minutes of
reaction time, carbothermic reduction of higher oxides
of manqanase and iron (Mn203 and Fe2o3) to manganeous
oxide (MnO) and metallic iron respectively was observed
which was controlled by diffusional process across the
boundary layer between the solid phases. Apparent
activation energy is calculated as 61.03 kJ for this
stage which corresponds to about 30 percent reduction.
Metallization started as random nucleation of iron rich
carbides around Mno grains inside the particle. After
30 percent reduction the formation of a silicate phase
was observed. Up to 70 percent reduction at 1350oC,
reduction rate was controlled by chemical reaction
between oxide phase and gaseous phase with an apparent.
activation energy of 153 32 kJ. / MT2017
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/22033 |
| Date | January 1991 |
| Creators | Burucu, E |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (various pagings), application/pdf |
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