Abstract
This study investigates phase transformations in copper-tellurium-containing middlings during vacuum-thermal processing at pressures of 0.066 and 13.3 kPa. It was found that at 0.066 kPa, industrial copper telluride undergoes oxidation through intermediate compounds to Cu3TeO6, which decomposes at 900°C via CuTeO3 into CuO and TeO2. At 13.3 kPa, the formation of CuTeO3 through the Cu3TeO6 was not observed. Technological tests showed the feasibility of tellurium recovery by the vacuum-thermal method in an inert atmosphere without additional reagents. It was found that reduced pressure and elevated temperature positively influenced the degree of tellurium transfer into the condensate. The highest recovery rates were achieved at 1100°C: 98.70% at 0.066 kPa and 96.79% at 0.133 kPa. The residual Te content in residues amounted to 0.72% and 1.62%, respectively. The findings expand scientific understanding of the thermal behavior of industrial copper telluride under vacuum conditions and provide a foundation for developing a new environmentally friendly method of processing tellurium-containing middlings. The creation of new technologies enhances the extraction efficiency of tellurium while reducing ecological risks.