Phase Transformations and Tellurium Recovery from Technical Copper Telluride by Oxidative-Distillate Roasting at 0.67 kPa

Abstract

This paper presents the results of a study of phase transformations occurring in copper-telluride by-products during its processing of oxidation-distillate roasting at low pressure. The results show that copper telluride is oxidized through intermediate compounds to the most stable tellurate (Cu3TeO6) at low temperatures. The increase in the roasting temperature above 900 °C and the presence of an oxidizer favor the copper orthotellurate decomposition. Thus, the tellurium extraction rate is 90–93% at a temperature of 1000 °С, the oxidant flow rate is 2.2 × 10−2 m3/m2·s, and the roasting time is 60–90 min. One of the decomposition products is copper oxide alloy, which is the basis of the residue. The second product is tellurium in oxide form, which evaporates and then condenses in the cold zone of the condenser in crystalline form. The main constituent phase of the condensate is tellurium oxide (TeO2), which can be further processed during one operation to elemental chalcogen by thermal reduction or electrolytic method.

Distribution of Rare Elements in Distillation Processing of Polymetallic Matte

“…The equilibrium distribution of selenium and tellurium upon distillation from copper chalcogenide alloys was studied by us earlier [29]. During the distillation of volatiles at low pressure, as a rule, at temperatures of 1100-1250 • C, the dissociation pressure of low-volatile pure copper sulfide will range from 0.5 to 7 Pa, copper selenide from 28 to 230 Pa, and copper telluride from 1.5 to 9 Pa. Consequently, copper sulfide and telluride completely, and copper selenide-mainly, will be concentrated in the distillation residue.…”

“…The behavior and distribution of the main components of sulfides during the distillation processing of matte in a vacuum, including lead and zinc sulfides, are given and The number of technological studies, in addition to those given in [13], is limited to works [25][26][27][28]. In [25], the authors studied rare metals' behavior on samples weighing 100 g at a temperature of 1200 • C and pressure of 65 Pa.…”

“…The authors of works [27] studied the formation of the phases and tested a method for the sufficient extraction of tellurium from the intermediate product of copper production (copper telluride) in the process of oxidizing roasting in a vacuum at temperatures above 1000 • C and a pressure of 0.67 kPa. Tellurium was extracted in the form of a mixture of oxides of various compositions.…”