The paper summarizes the results of studies on the use of ozone for the extraction of non-ferrous, rare and noble metals from ores, beneficiation concentrates and technogenic raw materials identified from world scientific publications and in patent literature since the early 20th century. Ozone is a strong oxidizing agent with an oxidizing potential 1.5 times higher than the potential of chlorine in an acidic environment. Even refractory metals and minerals dissolve with ozone. Metal extraction from mineral raw materials using ozone does not contaminate processed products or generate any hazardous waste. The paper presents a significant number of studies on the use of ozone to dissolve gold and other noble metals in mineral acids showing an increase in the extraction of metals into the solution. The cyanide and thiourea leaching of gold from mineral raw materials with the replacement of oxygen with ozone was investigated. The paper provides the results of the vat and heap leaching of non-ferrous and noble metals using ozone obtained by air or oxygen irradiation with ultraviolet light, in particular with the use of photoelectrochemical treatment. These results were used as a basis for patenting new technologies. The effectiveness of ozone used in the flotation concentration of mineral raw materials, purification and detoxification of solutions and solid products of metallurgical processing, regeneration of other oxidants, metal extraction from process solutions was evaluated. The results of studies on using ozone for the vat leaching of metals from refractory sulfide ores and sulfide beneficiation concentrates in an acid solution, and the study of the ozone-assisted oxidation kinetics of copper, iron, zinc, and molybdenum sulfide minerals are summarized. The paper provides and analyzes the results of using ozone in a combination with other oxidants – hydrogen peroxide and iron (III) ions – for metal extraction from sulfide mineral raw materials in a sulfuric acid. According to the results of most of the studies carried out, it can be concluded that the use of ozone is effective for metal extraction from mineral raw materials as it improves process performance (metal extraction into the solution, selectivity of metal extraction from complex raw materials), and reduces processing time.

Studies of the extractive recovery of Ca(II), Mg(II) и B(III) impurities from nickel production solutions at JSC «Kola Mining and Smelting Company» were conducted. As extraction agents, we used di-(2-ethylhexyl)phosphoric acid (D2EHPA), di-(2,4,4-trime-thylpentyl)phosphinic acid (Cyanex 272), trialkylamine (TAA), tributyl phosphate (TBP), aliphatic alcohols: octanol-1, 2-ethylhexanol and a by-product of its production – heavy product of 2-ethylhexanol distillation (TPRD). In order to assess the effect of conditions used to extract impurities from solutions, laboratory studies on the effect of aqueous phase acidity, extraction agent concentration, composition of organic impurities on their extractability were conducted. According to the research results, it was found that the optimal concentration of individual extraction agents is 20 vol.% each in the Escaid 100 solvent, and the mixture composition is 15 vol.% D2EHPA + 5 vol.% Cyanex 272 at Ca(II) and Mg(II) extraction. Individual D2EHPA predominantly extracts calcium (II): extraction of 62 % Ca(II) and 15 % Mg(II). When using Cyanex 272, the extraction of magnesium (II) predominates: extraction of 59 % Mg(II) and 20 % Ca(II). It was found that the extraction mixture has higher performance than individual extraction agents for Ca(II) and Mg(II) extraction from nickel solutions in the pH range of 3.0÷3.5, at which Ni(II) coextraction is negligible. With increasing pH values, Ca(II) extraction decreases due to the increasing extraction of nickel and the displacement of calcium by it from the organic phase. It was established that a mixture of 40 % TAA + + 60 % 2-octanone and heavy product of 2-ethylhexanol distillation exhibits high extraction ability with respect to B(III): the degree of boron extraction is 60.7 and 74.5 %, respectively. The paper provides the results of the extraction purification of the nickel electrolyte from JSC «Kola Mining and Smelting Company» with an extraction mixture in the Ni-form to exclude pH adjustment at each stage of the process. Based on the results of the studies conducted, a flowchart is recommended for obtaining pure NiSO4 solutions with a residual total B(III), Ca(II), Mg(II) and Cl– content of £0.010 g/dm3 .

 In Russia, most aluminum smelters are equipped with cells with self-baking anodes featuring an urgent problem of lowering the anode paste consumption, since the share of anode materials in the cost of aluminum varies from 8 to 20 %. To solve this problem, it is necessary to determine the anode paste demand. The method for calculating the specific anode paste consumption used at aluminum smelters has a poor accuracy. The paper discusses the main errors of this method, shows the stages of anode paste consumption calculation, assesses the adequacy of calculations and gives recommendations for method improvement. It is shown that in general the considered method adequately reflects carbon consumption processes, but the final result of calculations may differ significantly from the actual one. The values taken constant to simplify the calculation, in fact, may vary during the electrolysis, which leads to a significant change in the final result of calculations. For example, an increase in the CO2 fraction from 0.45 to 0.5 leads to a decrease in the anode paste consumption by 15.3 kg/tonAl. At the same time, it is known that the composition of anode gases changes sharply as the anode effect occurs: the CO2 fraction decreases, and the CO fraction increases. In summer, at high ambient temperatures, the proportion of both vaporized pitch and anodes with an increased surface temperature rise. As the latter changes to 0.25, the consumption increases by 6.6 kg/tonAl. The same applies to air oxidation. The number of depressurized cells may increase with the subsequent increase in the carbon consumption. It is necessary to pay attention to factors affecting the anode quality. Incorrectly selected particle size distribution or worn equipment may significantly degrade the anode quality and lead to an increase in carbon consumption. It is necessary to make adjustments to the calculation in order to consider the peculiarities of carbon monoxide formation properly.

Rotational viscometry with the FRS 1600 (Anton Paar, Austria) high-temperature rheometer was used to obtain temperature dependences of the dynamic viscosity of molten lithium and beryllium fluoride salts considered as candidate fuel and coolant compositions for the molten salt reactor (MSR) for burning long-lived actinides from the spent nuclear fuel of the PWR 1000/1200 pressurized water reactor. 0.66LiF–0.34BeF2 and (0.73LiF–0.27BeF2)+UF4 molten salt mixtures containing 1 and 2 mol.% UF4 were investigated with regard to the MSR intermediate and fuel circuits. Salt mixtures were prepared by the direct melting of components and certified using X-ray phase and elemental analysis. The «shear rate» parameter was selected according to the viscosity curves obtained in the studied melts at 700 °C. It was found that the viscosity does not depend on the shear rate in the range of γ = 6÷20 s–1. When measuring the temperature dependence of viscosity, the shear rate was 11 s–1. Viscosity values of LiF–BeF2–UF4 melts obtained from experiments in the temperature range from liquidus to 800 °C are described by the linear equation logη = a + b/t, but their temperature coefficients differ evidently, which indicates a significant dependence of the viscosity of these melts on composition and temperature. Viscosity values obtained for the 0.66LiF–0.34BeF2 melt agree with the available literature data within 7–10 % in the temperature range of 650–750 °C. With an increase in the LiF content, melt viscosity decreases: it is lower by 20 % in the 0.73LiF–0.27BeF2 melt at t = 650 °C. However, when 2 mol.% UF4 is added, the 0.73LiF–0.27BeF2+UF4 fuel salt viscosity increases by 10 % at the same temperature.

This review focuses on the known theoretical and experimental results in the field of obtaining metal matrix composite materials by processing the melts using physical methods in the conditions of casting and metallurgical processes. The possibilities, advantages and disadvantages of various physical impact methods are considered from the standpoint of their effect on the structural and morphological characteristics, physicomechanical and operational properties of cast composite materials based on aluminum and its alloys. The paper provides a classification and a detailed description of physical methods used for melt processing when obtaining metal matrix composites depending on the melt state during processing (melting, pouring and crystallization) and according to the physical principle of the effects applied (thermal, electromagnetic, cavitation, mechanical, etc). The paper describes a contemporary view of the laws and mechanisms of the effect exerted by melt processing using physical methods on the structure and phase formation processes of as-cast metal matrix composites. The currently known effects of the impact on their structure are described from a qualitative and quantitative point of view, in particular, effects associated with a change in the wettability of particles, their distribution, dispersion and morphology, as well as with a change in the structural state of the matrix material. The paper systematizes the data on the properties of metal matrix composites obtained using physical impacts on the melt during melting and crystallization. The research shows the prospects for the development and practical application of physical impact methods for melts in the production of metal matrix composites based on various matrix materials and reinforcement systems including endogenously, exogenously and integrally reinforced composite materials. Priority areas of theoretical research and experimental development are discussed highlighting discussion areas and issues in the field of obtaining metal matrix composites using physical impacts on melts during melting and crystallization. Areas for future research in this field are proposed based on the systematic analysis of key problems limiting the widespread industrial use of physical methods for melt processing.

The study covers the quality of a metal powder composition (MPC) made of a heat-resistant EP648 alloy (Ni–Cr–W–Mo system) used to produce parts by direct metal deposition (DMD). It was established that the MPC meets the TU 136-225-2019 specification in terms of basic requirements (chemical composition and grain size distribution, purity, bulk density, fluidity, moisture content). The effect of direct metal deposition parameters (laser radiation power, surfacing speed) on the structure and microhardness of test samples was studied. The largest number of defects (looseness, pores and lack of fusion) is formed in the sample obtained at a laser radiation power (RP) of 1000 W and a surfacing speed of 40 mm/s. At the same time, the defects have maximum dimensions. The smallest number of such defects is observed in samples obtained at a RP power of 1400 and 1600 W and a surfacing speed of 45 and 38 mm/s. In this case, the most homogeneous structure of laser surfacing zones is formed due to the complete melting of powder particles and the melt spreading. Nevertheless, the sample obtained at a RP of 1600 W and a surfacing speed of 38 mm/s has a structure with cracks located along the faces of subgrains in the center of surfacing tracks. Crack formation is caused by material overheating due to the increased laser radiation power and accumulated high internal stresses from the previous deposited layers. The microhardness of samples obtained at all direct metal deposition modes varies slightly and amounts to 270– 310 HV. According to the research results, it was found that the most optimal structure is formed in the sample obtained at a RP of 1400 W and a surfacing speed of 45 mm/s.

The article describes the development and pilot-scale testing of the technology for producing bars of the D16(T) aluminum alloy by radial-shear rolling from continuously cast billets with a diameter of 72 mm in several passes. The actual dimensions of rolled bars were within the ±0.16 mm tolerance for all bar diameters, which significantly surpasses the GOST 21488-97 requirements. According to the results of tensile tests, the values of ultimate strength, conventional yield strength, relative elongation and relative reduction were determined. Ultimate strength and relative elongation requirements specified by regulatory documents for the D16(T) alloy were met with a total elongation ratio of more than 4.2. In terms of plastic properties, the obtained bars surpass the GOST requirements by 2.1–2.5 times in the entire range of elongation ratios investigated starting from 2.07. At the same time, there is an increase in the relative elongation by 5.7–6.8 times in comparison with the initial cast state. The microstructure and morphology analysis conducted for secondary phases showed that with a decrease in the bar diameter (with an increase in the total elongation ratio), the average particle size of the α(AlFeMnSi) phase insoluble in the aluminum matrix decreases, which is a consequence of deformation processes developed during rolling. Additional grinding of inclusions during deformation processing can significantly reduce the possible negative effect of the insoluble phase on the mechanical properties of resulting bars, in particular on the plasticity properties. The microstructure analysis showed that bars after rolling and heat treatment are free from cracks, looseness, delamination, and other defects and meet the requirements of GOST 21488-97.