The paper considers the research results of structural-phase state and tribological characteristics of detonation coatings based on Ti–Si–C, obtained at different filling volumes of the explosive gas mixture barrel of a detonation gun. The results analysis indicates that the phase composition and properties of detonation coatings strongly depend on the technological parameters of spraying. With an increase of the explosive mixture in the filling volume of the detonation barrel up to 70% of the coatings consist mainly of the TiC phase, because high temperature leads to a strong decomposition of Ti₃SiC₂ powders. Thus, the XRD results confirm that at 70% of the explosive gas mixture’s filling volume, partial decomposition and disintegration of the powders occurs after detonation spraying. We established that detonation coatings based on titanium carbosilicide obtained at the explosive gas mixture’s filling volume at 60% are characterized by high wear resistance and adhesive strength. Thermal annealing was performed after spraying in the temperature range of 700–900 °C for 1 h to reduce microstructural defects and improve the Ti–Si–C coating characteristics. As a result of the heat treatment in the Ti–Si–C system at 800 °C, we observed that an increase in the volume fraction of the Ti₃SiC₂ and TiO₂ phases led to a 2-fold increase in microhardness. This means that the after-heat-treatment can provide a sufficient reaction time for the incomplete reaction of the Ti–Si–C (TSC) coating during the detonation gun spraying. Thus, annealing can provide an equal distribution of elements in the coatings.

This paper presents the results of a metallographic and tribological study of 86WC-10Co-4Cr coatings obtained by the HVOF method on the Termika-3 unit at varying spraying distances. The influence of spraying distance on the coating microstructure, phase composition, as well as mechanical and tribological properties, was studied. According to the results of the study, it was found that the optimum spraying distance for 86WC-10Co-4Cr coatings with improved wear resistance and hardness characteristics and low porosity is 300 mm.

Electrolytic plasma thermocyclic surface hardening is an attractive solution for both chemical and heat treatment used to improve the properties of the steel surface by structural and phase transformation. Structural and phase transformations occurring during the process of electrolytic plasma thermocyclic hardening are performed repeatedly at varying heating–cooling temperatures, which radically improve the quality of the part and give them properties unattainable by means of one-time processing. The impact of electrolytic plasma thermocyclic hardening modes on the structure and mechanical and tribological properties of 30CrMnSiA steel is investigated. The structural and phase components were examined using optical and scanning electron microscopy, as well as X-ray phase analysis. It is established that the structure of the cross-section is characterized by the following zonality: zone 1—a near-surface hardened zone, which is composed of hardened martensite; zone 2—thermal influence; and zone 3—a matrix consisting of pearlite and ferrite. The microhardness and wear resistance of the hardened surface were evaluated by nanoindentation and “ball on disk” methods, respectively. Nanoindentation analysis demonstrated that the indentation hardening process provides a maximum increase in hardness by three times and an increase in stiffness with a decrease in the elastic modulus by 38% compared to the original steel. The results of tribological studies show that electrolytic plasma thermocyclic hardening increases the resistance of steel to friction by increasing the surface hardness and reduces the area of actual contact during friction. It is established that the microhardness of the cross-section decreases proportionally from the surface to the depth of the layer, which is associated with a decrease in the volume content of martensite.

In this work, the influence of spray parameters on the formation of the microstructure, phase composition, and the tribological properties of detonation flame sprayed coatings was studied. It was determined that the chemical composition of Cr₃C₂-NiCr coatings during detonation spraying depends on the degree of filling the barrel with an explosive gas mixture. The degree of filling the barrel with an explosive gas mixture at 73 leads to a decrease in the content of carbide phases, and at 57 filling of the barrel, an increase in carbide phases is observed. It is established that the decrease of the filling degree leads to the increase of hardness and wear resistance of the Cr₃C₂-NiCr coatings since the hardness and wear resistance of the coating material deposited at 57 is higher than at 65 and 73; this is due to the increase in the carbide phase Cr₃C₂. Detonation flame sprayed Cr3C2-NiCr gradient coatings have been developed in this study, which is carried out by varying the spray parameters. It was found that in the gradient coating, Cr₃C₂-NiCr carbide phases gradually increase from the depth to the surface. The obtained gradient coating closer to the substrate consists of the CrNi₃ phase, while the coating surface consists of CrNi₃ and Cr₃C₂ phases.

The technology for obtaining hydrofluoric acid and the peculiarities of its production were studied, and the physical and chemical properties of the waste were examined. Activators that accelerated the hardening of the anhydrite binder were selected. The process of recycling fluorine hydrite waste from the production of hydrofluoric acid at Ulba Metallurgical Plant JSC was studied, and anhydrite unburnt binder with a setting time of 30 min was obtained. On the basis of the obtained data, a technological scheme of anhydrite binder production was developed. The effectiveness of the technological scheme was confirmed experimentally. This work aimed to study the possibility of the integrated use of secondary and anthropogenic raw materials from Ulba Metallurgical Plant, which represents an important means of not only increasing production efficiency and economic benefits and reducing the irrational alienation of land resources, but also protecting against the pollution of water and air basins, as the environmental policy of UMP JSC is nowadays of great importance.

This article presents a study on the precipitation of copper from the cyanide leaching solutions used for gold–copper ores, both with and without the addition of a sulphidizer (Na₂S). Mathematical models were developed to summarize the effects of the pH, initial copper concentration, and Na₂S stoichiometric ratio on the precipitation process, using an experimental design based on a probabilistic–deterministic method. Varying the stoichiometric ratio of Na₂S has a minimal impact on the precipitation process. However, the presence of a sulphidizer is significant, as the precipitation process occurs at pH levels of 5 and below. The initial concentration of copper in the solution was identified as the most significant factor. At copper concentrations of 0.34% and 1.55% (pH = 3), the precipitation rates were 51.48% and 47.6%, respectively. This study also determined that the most effective method across the entire range of copper concentrations in the solution was the precipitation of copper in the form of copper cyanide hydrate (CuCN∙nH₂O) without the addition of Na₂S. At copper concentrations of 0.34% and 1.55% (pH = 3), the precipitation rates were 86.47% and 85%, respectively. The pH level was the most significant factor influencing this process, as copper deposition without Na₂S did not occur at a pH of 5. The obtained models allow us to accurately predict the influence of factors on the deposition process. Aided by the mathematical model of precipitation (without Na₂S), we selected the conditions for an enlarged experiment using 20 L of solution (Cu = 0.34%, pH = 3.2), which showed the high efficiency of the method. The calculated recovery amounted to 86%, where practical recovery was 87.2%, and divergence was ≥1.2%.