Development of an Oxidizing-Distillation Technology for the Extraction of Tellurium from a Tellurium-Containing Middling

- In this paper, the results of studying aimed at tellurium extraction from its compound with copper in the form of oxides by the pyrometallurgical method are presented. Technical copper telluride of Kazakhmys Corporation LLP containing crystalline phases, %: Cu 7 Te 4 – 36.5; Cu 5 Te 3 – 28.5; Cu 2 Te – 12.9; Cu 2.5 SO 4 (OH) 3 ·2H 2 O – 16.2 and Cu 3 (SO 4 )(OH) 4 – 6.0 was used as an object of research. As a result of the physical and chemical research and technological experiments, the fundamental possibility of processing technical copper telluride by oxidative distillation roasting with the extraction of tellurium into a separate product has been shown. Air oxygen was used as an oxidant. It has been established that a pressure decrease at the same temperature entails an increase in the degree of tellurium extraction. However, from a technological point of view, the value of the degree of tellurium extraction (93.0–98.0 %) at all pressures (within 1 hour) is achieved at a temperature of 1100 °C. Increasing the exposure to 3 hours has a minor beneficial effect. The derived condensate is a free-flowing mixture of crystalline phases of tellurium dioxide and tellurium oxysulfate. This condensate is a middling product for further production of elemental tellurium.