The effect of petrographically determined parameters on carbonaceous reductant reactivity in the production of high-carbon ferromanganese
Date
2024
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Abstract
In pyrometallurgical processes, metal oxides are reduced from slag through carbothermic reduction. The carbonaceous reductant reactivity to slag is of industrial interest as it provides information such as the rate at which MnO dissolves in the slag, which ultimately influences the manganese yield in the alloy.
However, knowledge is limited on the effectiveness of organic composition of the reductants when heated and its contribution that gives rise to the differences of the reductant reactivities of the chosen reductants. This study compares the effect of organic composition of coal on the reductant reactivity to slag. The objectives of the study are
(1) To determine empirically reductant reactivity to slag
(2) To determine petrographically the intrinsic organic properties of the bituminous coal and anthracite as reductants
(3) To compare the fundamental properties and characteristics of bituminous coal and anthracite
The study examined two medium-rank C bituminous coals—labelled coal 1 and coal 2—and anthracite. It investigated the effect of petrographic characteristics on carbonaceous reductant reactivity to slag. The reductant reactivity towards slag tests were conducted in a gas-tight muffle furnace at 1500°C applicable to the chosen three carbonaceous materials. Analytical techniques, such as SEM-EDS, were applied to measure the extent of MnO reduction (and SiO2 to a lesser extent) from the slag. It was expected for MnO and SiO2 from slag to be partially reduced to form Mn and Si in the alloy phase. Other analytical techniques were applied, such as proximate analyses, which indicated the differences and similarities between the chosen carbonaceous reductants as the fundamental basis for evaluating coal for technological use. The maceral data revealed coal 2 consisted of a greater proportion of reactive macerals than coal 1 and anthracite. The anthracite sample, consisting of the highest inert maceral proportions, had the least mass loss.
Description
A research report submitted in partial fulfilment of the requirements for the degree Master of Science in Engineering to the Faculty of Engineering and the Built Environment, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, 2023