Pre-reduction Behaviour of Manganese Ores in H₂ and CO Containing Gases

Abstract

This paper presents results of a study conducted on the pre-reduction of Assmang and Comilog ores with gases of CO+CO₂ and CO+H₂+CO₂ up to 1000°C. Non-isothermal experiments were carried out in a vertical thermogravimetric tube furnace. Four different gas mixtures were considered. That is, gas mixtures of 50%CO/50%CO₂, 41%CO/18%H₂/41%CO₂ and gas mixtures of 70%CO/30%CO₂, 41%CO/41%H₂/18%CO₂ whose CO/CO₂ ratio is respectively of 1/1 and 2.3/1. The ore and reduced samples were characterized by X-ray fluorescence technique followed by a scanning electron microscopy analysis. The extent of reduction was considered based on the recorded weight loss together with the chemical analyses done on the processed samples. It was found that for the same oxygen pressure, the highest reduction rate was achieved when hydrogen was present in the gas mixture. Results also showed that when the oxygen pressure of the gas mixture was lower, the reduction rate was the highest as expected.