The partial pressures of saturated vapor of the components in the Se–Te system are determined and presented in the form of temperature–concentration dependences from which the boundaries of the melt–gas phase transition are calculated at atmospheric pressure and vacuums of 2000 and 100 Pa. The existence of azeotropic mixtures is revealed. It is found that the points of inseparably boiling melts correspond to 7.5 at % of Se and 995°C at 101325 Pa, 10.9 at % at 673°C and 19.5 at % at 522°C in vacuums of 2000 and 100 Pa, respectively. A complete state diagram is constructed, including the fields of gas-liquid equilibria at atmospheric and low pressures, the boundaries of which allow us to assess the behavior of selenium and tellurium upon distillation fractionation.

The values of partial pressure of saturated vapor of the constituents of the Те–S system are determined from boiling points. The boundaries of the melt–vapor phase transition at atmospheric pressure...

The heterogeneity and local distribution of elements are established as a result of the study of nonferrous metals distribution and the composition of domestic wastes processing concentrate containing 20–40% copper, 40–50% brass, 20–28% zinc and up to 1% aluminium. Metals are mainly concentrated in granules of three types: zinc-based, copper-based and copper–zinc alloy, i.e., brass. The phase composition of these granule types and their structure are determined. Zinc granules are covered with a refractory oxide shell. A distillation processing method for such raw materials based on full state diagrams, including the phase transition of melting pairs of double systems of copper and tin with zinc and lead, is offered. The possibility of a rather complete zinc distillation (over 90%) with the accumulation of other metals in the copper-based alloy, containing more than 96 wt. % of the basic element, has been demonstrated by electric crucible melting in a highly reducing atmosphere. Copper-based alloys, after adjustment for the content of some metals (tin), can be realized as pressure-treated tin bronzes. Copper with the content of impurities corresponding to the standard for blister copper can be electrolytically processed (after dissolution in sulphuric acid) in copper production. Equipment for the implementation of the electro-thermal processing process that provides metal recycling of the metal concentrate is proposed.

A short review of well known and currently used in production sector methods of selenium-containing slurries processing of copper and nickel productions are provided in this paper. The process flow scheme of copper anode slime processing at the Balkhash copper-smelting plant of Kazakhmys Smelting LLP is provided. The copper anode slime obtained after copper electrolysis is processed in the Kaldo furnace at the refining section of the precious metal shop where the metal roasting, smelting and converting are combined. The main product of the Kaldo furnace is the Dore alloy to refine gold and silver. Raw selenium containing ~ 80% of the main component, copper telluride and bag filter fines containing precious metals except for selenium are obtained as a by-product. While Kaldo furnace operation, the exhaust service gases pass through the gas trapping and treatment system. The current gas treatment system consists of three in series connected devices, such as a gas scrubber cooler (a quenching tower or a cooling tower), a Venturi scrubber and a cyclone separator. When gas trapping process the fines is deposited, selenium dioxide and arsenic trioxide are dissolved, and some metal chlorides are absorbed in the circulation solution. The 15 m3 of pulp with 40-50 g/dm3 of solid substance, and 20-50 g/dm3 of selenium in the solution, 2-5 g/dm3 of chlorine, the pH value is from 0 to 1 is formed after all stages of service gases trapping and treatment in the circulation tanks. After the metal hydroxides are deposited, the pulp is going through filter and sent to the selenium sedimentation stage. The precipitate after filtration (Venturi slurry) is a recycled product and is processed in a Kaldo furnace. Selenium precipitation is performed at a 70 °C temperature with sulfur oxide (IV) within 6-10 hours. Selenium obtained under this scheme was segregated in the smelting furnace and then vacuum distillated. As a result of these a brand metal with main component content of more than 99.5 % corresponding to the ST1 brand under GOST 10298-79 intended for export was obtained.

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 °C, 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.

Due to the lack of data on the double film Nb-Cd system thermal stability, the effect of thermo-vacuum treatment of cadmium solid solutions in niobium, in intermetallic compound NbCd2 and in cadmium-based alloys on the structure of materials was studied. A step-by-step isochronous annealing at a temperature of 300 and 500°C and a pressure of 1·10-3 Pa was used as the research method followed by tracking changes in the composition and structure by comparing the diffractometric data before and after heat treatment. The amount of cadmium in the coating, the sublimation (evaporation) rate of cadmium from film coatings was determined based on the previously established dependence of the lattice parameter of the body-centered cubic lattice of solid solutions on the composition. As a result, the heating of film coatings (49.0 - 64.5 at % Cd) represented by solid solutions in high vacuum up to 300°C was founded to be accompanied by the onset of intense degradation of the crystalline niobium-cadmium system due to the diffusion of cadmium atoms to the solid phase-vapor interface and its subsequent sublimation. Coatings from the NbCd2 intermetallic compound which is a degenerate semiconductor and cadmium-based solid solutions (72.5 and 76.8 at % Cd) including the amorphized phase of the intermetallic compound, after exposure at this temperature are degraded due to the complete transfer of cadmium to the vapor phase by evaporation. Upon thermal exposure to a temperature of 200°C, the structure of solid solutions of cadmium in niobium and the NbCd2 intermetallic compound was stable.