C. Rhee, C. S. Kim, K. Li
Aug 1, 1973
Environmental science & technology
Pneumatolytic transport is a promising process for conserving natural resources by recovering valuable metallic iron as a product from iron ore flotation tailings presently disposed of as a solid waste. As the first step this finely divided material was reduced by carbon monoxide in a fluidized bed. The particles were not observed to react topochemically. The reduction data a t pressures up to 4.4 atm and temperatures from 593-704°C were interpreted by means of a simple two-step model which postulates that the overall rate of reaction is controlled by both chemical reaction of the homogeneous type and mass transfer between the gas and solid phases with a decreasing effective transfer area due to sticking and defluidization. During reduction, carbon deposition occurred at an approximately constant rate after an initial delay. The total carbon and combined carbon were found to increase approximately linearly with the overall reduction a t a given temperature. It is believed that the combined carbon, mainly cementite, is formed by the reaction between metallic iron and carbon monoxide and that the reaction does not play a direct role in reducing oxides.