The paper covers experimental and theoretical studies of technical solutions for copper liquid extraction by organic extractants from sulfuric acid solutions that neutralize the negative effect of hydrogen ions released as a result of copper cations interaction with oximes on the copper extraction into the organic phase, and increase the technical and economic parameters of the process. In order to reduce the volume of processed solutions, copper extraction by the extractant solution in a diluent from the previously obtained thickened copper precipitate by sodium carbonate addition was studied. Subsequent operations for copper organic phase purification from metal impurities and re-extraction were carried out by methods known in liquid extraction. It was experimentally found that the use of copper pre-concentration in the precipitate makes it possible to increase the copper content in the extractant by 3—4 times to 1 g per 1 % (abs.) of the oxime content in the organic phase. It is required to maintain a ratio of 2 moles of oxime to 1 mole of copper in the precipitate to ensure rapid delamination and full extraction of copper. Dependencies of parameters were calculated for the stages of copper extraction from the thickened solution precipitate and extract washing. It was shown that extraction system parameters can be increased by using copper from the extractant emulsion solution obtained by mixing the oxime solution in a diluent and the aqueous solution of sodium carbonate. Based on the results of experiments, extractant emulsion with sodium carbonate added into the first stage of the extraction process makes it possible to significantly increase the copper distribution coefficient and saturate the extractant in terms of copper as much as possible. Maximum copper extraction from the solution is achieved at a molar ratio of carbonate and oxime in the emulsion equal to 1 : 2. The proposed technical solutions increase distribution coefficients and maximize the extractant working capacity during copper extraction. The lower volume of phases involved in extraction results in a substantially reduced number of extraction equipment and costs of raffinate purification from extractant and diluent destruction products. The proposed extraction methods can be used to extract copper from natural and technological sulfuric acid solutions, for example from mine waters and solutions generated when processing mineral raw materials and man-made waste.

The effect that the main parameters of zinc electrolysis from an alkaline zincate solution have on current efficiency and power con­sumption was studied in laboratory conditions. Zinc concentration (initial and final), current density and temperature were chosen as variable parameters. The study used both model electrolytes (prepared using standard reagents) and real ones produced by leaching the calcined middling product obtained when processing zinc-bearing dusts of ferrous metallurgy. It was shown that the current efficiency of zinc can be quite high (more than 90 %) even at an initial zinc concentration in the alkaline electrolyte of 10 g/dm³. However, this requires low current loads (100—400 A/m²) that are impractical in industrial electrolysis used to produce powdered metal, since the actual current density decreases as the cathode deposit surface develops and may fall below the limiting diffusion current of complex ions. In this case, the growth of enlarged dendrites is expected with the formation of «short-circuited» sections in the interelectrode space, which as a whole will reduce the zinc current efficiency. Larger-scale laboratory studies focused on zinc electrolysis from a real zincate solution made it possible to determine the most energy-efficient (with the highest zinc current efficiency and the lowest power consumption) process parameters: current density — 1000—2000 A/m²; electrolyte temperature — 50—80 °С; initial zinc concentra­tion — 20—50 g/dm³; residual zinc concentration — not less than 15 g/dm³. These conditions will ensure high current efficiency (85 — 95 %) and electric power consumption (2,28—3,20 kW-h/kg_Zn). For the «depleted» zincate solution with a zinc content of 10 g/dm³, the highest current efficiency (more than 90 %) is achieved at a current density of 125 A/m², close to the diffusion current density j = = 95,7 A/m². With j > 500 A/m², the current efficiency is significantly lower due to the intensive hydrogen release. A qualitative evalu­ation of the resulting cathode deposit was made (by the visible dimensions of crystals) in studies on an enlarged electrolytic cell.

The paper relevance is determined by the need to create an environmentally safe, high-performance and cost-efficient integrated vacuum distillation technology for the processing of lead-containing middling products and wastes, in particular, a Sb-Pb-Ag (SPA) alloy resulting from the recovery of silicate slag from copper anode slime melting to obtain sellable mono-element concentrates of an­timony, lead and silver. Laboratory studies were carried out on SPA alloy processing with the calculations of «T—x» temperature-com­position VLE (vapor liquid equilibrium) diagrams to analyze the behavior of Sb-Pb and Pb-Ag binary alloys during processing, select preliminary system temperature and pressure, and assess component separation efficiency in the following conditions: T = = 900+2100 K, P = 1+133 Pa, т = 8+16 hours. The aim of the study was to investigate the effect of temperature and pressure in the system, the duration of sublimation on the completeness of extraction and the degree of antimony, lead and silver separation from the SPA composition. Activity coefficients of binary alloy components when constructing VLE diagrams were calculated using the MI- VM (molecular interaction volume model). The information is obtained regarding the effect of temperature and vacuum level on the
degree of sublimation and separation of metals from Sb—Pb and Pb—Ag compositions of different contents. Saturated vapor pressures were calculated for Sb (p* = 273.664+ 67436.9 Pa), Pb (0.149+485.9), Ag (5.05440^-5-6.558) at T = 1073+1773 K. It was demonstrat­ed that the high values of the pSb /PPb = 1832.98+138.79, рр_ь /pA_g = 2948.16+74.09 ratio and lgPsb = 2.099+3.33 and lgPp_b = 1.813+ +3.944 separation factor create theoretical prerequisites for a selective isolation of these metals by vacuum distillation, when anti­mony and lead are successively enriched in the gas phase (Ps^ > 1, Pp_b > 1), and silver — in the liquid phase. The molar fraction of hard-to-sublimate lead/silver in the gaseous phase ур_Ь /уA_g = (1.55+982)T0^-3/(36+772)T0^-3 is increased with rising temperature 894+1601/1399+2099 K, pressure 1.33+133 Pa and metal content in the alloy x_Pb /x_Ag = 0.9+0.9999/0.9+0.99. The MIVM model was used to calculate the activity factors of antimony Ysb = 0.832+0.999, lead yp_b = 0.474+1.0, YA_g = 0.331+0.999 for Sb/Pb and Pb/Ag al­loys with the following composition 0.1+0.9/0.9+0.1 in the investigated temperature range. The found dependences of the amount and composition of polymetallic alloy sublimation products on the process parameters are important for practical application due to the development of a principal technology for SPA processing by vacuum distillation.

The paper presents an overview of methods for obtaining perovskite structure titanates and doping them with rare-earth elements. The results of scientific research conducted by authors from different countries related to the study of the effect of doping perovskite structure titanates with rare-earth elements on their electromagnetic properties are discussed. The paper also comprises information on the use of perovskite structure titanates in various industries. As exemplified by barium titanate (BaTiO3), a comparative analysis of some morphological properties (particle size, structure) and electromagnetic characteristics (dielectric constant, Curie temperature, modulus of longitudinal oscillations (d33)) of powders obtained (and doped) by different methods is carried out. Techniques for various BaTiO3 preparation methods such as solvothermic, hydrothermal, sol-gel, chemical deposition, and solid-phase sintering are described. The paper provides the results of studies on the effect of changes in process parameters (temperature, pH, composition of the initial mixture of materials and concentration of reagents) on the phase, morphology and BaTiO₃ particle formation rate in hydrothermal synthesis (using BaCl₂, TiCl₄ and NaOH as initial materials). In addition, experiments were conducted to study the effect of microwave radiation power in ВаСОз and ТЮ2 solid-phase sintering on the dielectric and ferroelectric properties of ВаТЮз ceramics. The analysis of methods for obtaining BaTiO3 and doping it with rare-earth elements found that at present the hydrothermal method and the method of solid-phase sintering (including with microwave radiation) can be regarded as advanced technologies for obtaining perovskite structure materials with predetermined properties.

Mannesmann piercing of ingots, which were made of aluminum alloy by casting, was done using plugs of different shape: entire plug, plug with cavity and hollow plug. Plugs had same diameter of calibrating segment. Piercing was carried out at 400 °C ofbillets. Influence of plugs’ shape on variation of hollow shells’ diameter, wall thickness and density along their length was estimated. Hollow shells were cut into 15 equal rings to measure density using hydrostatic (Archimedean) weighing. Experimental operations were simulated using FEM computer software. Casting was simulated using ProCAST, piercing — using QForm. Variation of hollow shells’ diameter, wall thickness and density along their length was estimated after simulation had been done. Experimental and simulation data were compared to check FEM simulation accuracy. Difference between experiment and simulation for density was not more than 2 %, for hollow shells’ dimensions — 20 %. Conducted investigation allowed estimation of how plug’s shape affects hollow shells’ dimensions accuracy and density. It was established that hollow plug or plug with cavity, in terms of dimensions accuracy and density variation, are preferable for piercing. Each of plugs being used, provides manufacturing of hollow shells with maximum density for all volume except close to hollow shell’s edges domains, where density is 1 % less than maximum value.

The analysis of scientific and technical literature and practical data made it possible to found that changes in casting parameters for ingots using different mold designs allows varying the degree of ingot grain structure refinement in a sufficiently wide range, which should be reflected in the conditions of aluminum alloy profile extrusion as well as physical and mechanical properties of these profiles. Therefore, the purpose of the research was to assess the influence of the degree of grain structure refinement for Alloy 6063 ingots on extrusion deformation and speed parameters and mechanical properties of profiles produced. The study used several batches of Alloy 6063 ingots 178 mm in diameter cast under industrial conditions, as well as profiles obtained by direct extrusion on a 18 MN horizontal hydraulic press subjected to quenching and aging. The grain size in homogenized ingots was estimated by light microscopy using the Olimpus optical microscope, and mechanical properties tests were carried out using the Inspect 20 kN-1 universal test machine. It was found that the initial grain size in the ingot structure exerts a significant influence both on ingot plasticity during extrusion, and on the final structure and mechanical properties of profile products made of aluminum alloys. Having analyzed the results obtained, we can conclude that the increase in strength characteristics of products extruded from ingots with a more refined structure is due to the fact that fine grains are retained in the structure of metal after its deformation, and cast metal plasticity increases with the degree of grain structure refinement in the ingot. This leads to the higher efficiency of profile product hardening and metal outflow rate during extrusion.

The studies of fractional, chemical and phase compositions of aluminum-containing slags of different origin found that slags are multi-component systems consisting of metal and non-metal parts. The non-metal part contains water-soluble and water-insoluble
components. A practical scheme for recycling aluminum-containing slags was proposed in order to isolate the water-insoluble component to be further used a secondary refractory dusting material. It was found that the secondary refractory dusting material has a positive effect on the quality of refractory ceramic molds in investment casting and the surface finish of experimental aluminum castings. This material improves the strength of refractory ceramic molds by 9 times in comparison with silica sand molds and increases gas permeability by 15 % to 33 % in comparison with fused alumina and silica sand molds, respectively. The study covers the processes used to produce refractory ceramic molds based on the secondary refractory dusting material. The mechanism of interaction between dusting material particles and suspension is theoretically justified in terms of colloid chemistry. Negatively charged aluminum
hydroxide micelles appear when ceramic mold layers are formed using the secondary refractory dusting material. Interaction between differently charged Al(OH)3 and SiO2 micelles makes secondary refractory dusting material particles come in close contact with each other. The theoretically justified processes of ceramic mold layer formation with the secondary refractory dusting material make it possible to explain the reduction in the surface roughness of castings made of AK9ch aluminum casting alloy using investment casting by 3.7 times compared with standard production processes.

The possibility of the increase of the properties of ceramics in the TaSi2–SiC system via the reinforcement by the SiC nanofibers formed in situ in the combustion wave has been studied. For the formation of nanofibers as well as for increase of the exothermicity of the reaction mixtures, energetic additive PTFE (C2F4) was used. Using the method of self-propagating high-temperature synthesis of the mechanically activated mixtures, 70%TaSi2+30%SiC ceramic was produced, with SiC present as the round-shaped grains and as nanofibers. Ceramic specimens sintered by hot pressing were characterized by relative density up to 98 %, hardness 19,0–19,2 GPa and fracture toughness 7,5–7,8 MPa·m1/2, which is noticeably above the fracture toughness of the ceramic with similar composition produced without the PTFE additions.