SULFUR DIOXSIDE UTILIZATION BY THE TREATMENT OF PYRITE- CHALCOPYRITE SULFIDE CONSENTRATES, COMBINING MECHANICAL AND METALLOTHERMIC PROCESSES

Abstract

In the research a new non-conventional tec hnology for the treatment of local pyrite-chalcopyrite sulfide concentrates is suggested allowing to extract copper and iron from the concentrates by an energy-saving, efficient and ecologically friendly method. For this purpose the reactivity of pyrite-chalcopyrite sulfide concentrates was enhanced for further intensification of metallurgical processes and obtaining of the copper-iron ligatures by direct aluminothermic reduction of activated concentrates. With the object of increasing the chemical activity of pyrite-chalcopyrite concentrates, they were subjected to preliminary mechanochemical activation in the vibratory mill. Fine grinding was carried out in air, water and applying other combined methods. In all cases mechanochemically activated copper and iron sulfides underwent deep chemical transformations forming metal sulfates, hydrosulfates, and partly oxides. Thus, mechanical activation of sulfides led to the same effect that takes place during the low-temperature roasting in the furnace. Then the mechanochemically activated (MA) concentrate was reduced by aluminothermy. The combination of mechanochemistry with the metallothermy allowed to perform a unique reduction process with more efficiency, and to obtain modified copper-iron ligatures bypassing the roasting processes common for the traditional metallurgy that lead to formation of volatile sulfur oxides. The structure of the obtained ligature was also examined. Metallographic analysis shows that it depends on the duration of mechanochemical activation. It is characterized by the microheterogenous nature, is more dispersed and presents a mechanical mixture of iron and copper (47% Fe, 53% Cu).