DTA/TG study of CuO and MoO3 co-reduction by combined Mg/C reducers

The mechanism of copper (II) oxide and molybdenum (VI) oxide co-reduction by Mg + C mixture was investigated at non-isothermal conditions by carrying out simultaneous differential thermal (DTA) and thermogravimetric (TG) analyses combined with X-ray diffraction (XRD) analysis of intermediate and final products. The whole process was found to involve several phenomena: interaction between oxides with CuMoO 4 salt formation, high-exothermic reactions occurring directly between metal oxides and magnesium, as well as low-exothermic carbothermal reactions. In order to better understand the complex nature of calorimetric and TG curves, the behaviour of each single reagent as well as that of binary, ternary and quaternary mixtures was studied at linear heating. It was revealed that the simultaneous reduction of Cu and Mo oxides proceeds more easily by carbon than by magnesium. Only due to the decisive role of carbon on the reaction pathway, the combined and complete reduction of oxides by Mg/C reducing mixture becomes possible at relatively low temperatures. The sequence of chemical reactions possibly occurring during the heating process on the basis of DTA/TG curves and XRD analyses results of quenched reaction products has been proposed.