The carbothermic reduction of Australian Groote Eylandt manganese ore and TEMCO ferro-manganese slag was studied thermogravimetrically. Samples were prepared by intimately mixing calcined manganese ore or slag and graphite. Experiments were performed using graphite crucibles at temperatures ranging from 1000 deg C to 1550 deg C under Ar-CO gas atmospheres. In a number of experiments, concentratiosn of CO and CO_2 in the off-gas were monitored using infra-red analysis. Samples reduced to different extents were examined using a FESEM, electron microprobe and optical microscopy. Data on the rate of reduction and phase composition were used to elucidate the reduction mechanisms. Rate and extent of the manganese ore reduction increase with increasing temperature. Silica has a strong retarding effect on the rate of manganese reduction. Addition of CO to the argon atmosphere markedly decreases the rate of ferromanganese slag reduction, but has a less retarding effect on the rate of manganese ore reduction.
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