CARBOTHERMIC REDUCTION BEHAVIOR OF WESSEL MANGANESE ORES

Characteristics of carbothermic reduction of manganese ores have been studied by classical thermogravimetric techniques in the temperature r ange 1100-degrees-C and 1350-degrees-C. Reaction products have been in vestigated by utilising X-ray diffraction, Scanning electron microscop y, Energy dispersive Analysis and Image Analysis. The effects of parti cle size and different gas atmospheres have also been studied. On the basis of the findings, a two stage mechanism has been proposed. First stage includes the reduction of higher oxides to their lower states by carbon and carbon monoxide. During this rapid initial stage the produ cts were porous to varying degrees. In this stage rate control appears to be mixed, both inward diffusion of carbon monoxide and outward dif fusion of carbon dioxide across the product layer and the reaction of carbon monoxide on the pore walls of oxide phase play important roles. During the second stage, the reaction is limited to the interface bet ween manganese oxide and a mixed carbide of iron and manganese. The ch emical reaction between the oxide and carbon appears to be the rate co ntrolling mechanism.