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

This paper presents results of a study conducted on the pre-reduction of Assmang and Comilog ores with gases of CO+CO2 and CO+H-2 +CO2 up to 1 000 degrees 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%H-2/41%CO2 and gas mixtures of 70%CO/30%CO2, 41%CO/41%H-2/18%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.