EFFECT OF TEMPERATURE AND CHARGE PREPARATION CONDITIONS ON THE CONVERSION DEGREE OF MOLYBDENUM MIDDLING DURING SODA ROASTING BASED ON CO₂ RELEASE

Аннотация

This study investigates the conversion degree of molybdenum middling during soda roasting based on the amount of CO₂ released. The initial molybdenum middling obtained from the Shatyrkul-Zhaysan cluster was characterized by chemical analysis, X-ray diffraction, mineralogical analysis, and SEM-EDS. The material contained 22.23% Mo, 7.52% Cu, 16.54% Fe, and 28.6% S, with molybdenite and chalcopyrite as the main mineral phases. SEM-EDS analysis confirmed the presence of Mo-, S-, Cu-, and Fe-bearing phases, as well as gangue and oxidized components. Soda roasting was carried out using a charge composed of molybdenum middling and sodium carbonate at a mass ratio of 1:1. The conversion degree was calculated from the integral volume of CO₂ released during roasting. The results showed that simple mechanical mixing of the charge provided a conversion degree of 16.9–39.7%, indicating limited interaction between solid reactants. When vibration was applied during roasting at 650 °C, the conversion degree increased to 49.33%. The highest conversion degree, 54.89%, was achieved when vibration during roasting was combined with preliminary moistening of the charge by adding 10% water. Chemical analysis of the roasted products showed that the lowest sodium content, 17.766%, corresponded to the maximum CO₂-based conversion degree, indicating more active participation of sodium carbonate in soda roasting reactions. The obtained results show that the efficiency of soda roasting depends not only on temperature but also on contact conditions between sodium carbonate and sulfide mineral particles.