The paper provides the results of theoretical reactivity calculations for gold, molybdenum, stibnite, galena, chalcopyrite, arsenopyrite and pyrite in comparison with such experimental data as the floatability of monomineral fractions with butyl xanthate, wetting angle values, changes in the kinetics of the mineral electrode potential. The following calculation series in terms of reactivity and oxidizing ability were established by calculation: Au < Sb₂S₃ < MoS₂ < PbS < CuFeS₂ < FeAsS < FeS₂. During the Hallimond tube flotation, natural gold grains demonstrated the highest recovery (70 %) in the рН = 5÷7 range compared to all the studied sulfides. Molybdenite and stibnite are floated at the level of 50 % under the same conditions. As pH increases towards the alkaline region, a decrease in the floatability of all sulfides except for chalcopyrite is observed. It was established that the highest recovery is achieved when the required time of conditioning with the collector is the inverse of their reactivity. The measured wetting angle of a drop of water on an untreated surface has the highest value (78°) for a gold plate, and the lowest one (67°) for pyrite, but the latter features the greatest increase in the wetting angle (by 15°) after treatment with butyl xanthate at a concentration of 10–4 mol/l and pH = 6. For molybdenite, treatment with butyl xanthate has practically no effect on the measured wetting angle. The Sb_2S3 < PbS < CuFeS₂ < FeAsS < FeS₂ series is determined according to the electrode potential in the рН = 2.0÷5.6 range. Theoretical calculations and experimental data obtained when studying monofractions of sulfides and gold showed that experimental conditions (pH, conditioning time, collector concentration) significantly affect the floatability. The calculated reactivity of chemical sulfide compounds and gold in comparison with experimental results proved the importance of maintaining certain flotation conditions to create contrast in the floatability of minerals.

The paper presents the results of studies on the use of collecting agents in the form of an inverse microemulsion (IМE) of the «water in oil» type (i.e. suspended water droplets are in the oil phase) for the flotation extraction of lead and zinc minerals. Lead and zinc concentrates, lead-zinc ore were used as initial samples for flotation. The content of galena in the lead concentrate was 74.7 %, and the content of sphalerite in zinc was 78.7 %. Basic collecting agents in the IМE composition were potassium butyl xanthate (PBX) and kerosene. A nonionic surfactant (NSA) was used for IМE stabilization. Casein was used as additives to main reagents to remove the negative effect of osmotic pressure during the IМE preparation. Casein was transformed into the active soluble form using sodium sulfide. The particle size in the inverse microemulsion was 12.38 nm. In flotation tests, the following options for feeding reagents to the flotation pulp were studied: IМE, IМE + frother, potassium butyl xanthate + frother. The T-92 reagent was used as a frother. PBX consumption as part of IME and in the traditional feeding was 26 g/ton. The results of laboratory tests showed that the method of feeding flotation reagents in the form of IМE leads to both an increase in the flotation rate of lead and zinc sulfides and an increase in their recovery into a foam product. In addition to the increased flotation speed, tests with the use of IМE in the bulk lead-zinc ore flotation cycle showed an increase in extraction into the ultimate concentrate by 10.8 % for lead, by 38.5 % for zinc, in comparison with the traditional feeding of reagents (collector + frother). An increased selectivity of the IМE effect in relation to zinc sulfides, in comparison with lead sulfides, was noted. The flotation rate coefficient of sphalerite is 7.8 times greater than that of galena. An increase in extraction into the ultimate zinc concentrate is also higher and amounted to 16.78 %, while for the lead concentrate it is 1.9 % under the same conditions.

The effectiveness of using materials based on rare earth elements (REE) largely depends on their impurity composition, which affects their structure and properties. Before the analytical quality control of REE-based materials and initial substances for their production, it is necessary to determine both macrocomponents and impurity elements with high sensitivity and accuracy. A complex of atomic emission and mass spectral analytical methods is often used for the determination of impurities in REE-based materials in the range from 10–5 to 5.0 wt.%. However, the analysis of such materials, even using these modern high-sensitivity methods is a difficult task due to spectral and matrix interferences. Therefore, different preliminary separation/concentration procedures are needed to determine both rare earth and other impurities. This article reviews publications is devoted to preconcentration methods for spectral and mass spectral analysis of REEbased materials and, in part, a number of other analytical techniques. It was shown that the most common approaches are liquid extraction and chromatography. Sorption, cloud-point extraction and coprecipitation are also used. There is no universal method. Each of the methods discussed in this article has its own advantages and limitations. The analytical completion of the method confirms the effectiveness of the selected separation/concentration method in each specific case.

The paper presents the results of studies into tellurium extraction from its compounds with copper in the form of oxides by the pyrometallurgical method. Commercial copper telluride of Kazakhmys Corporation LLP containing crystalline phases, wt.%: Cu₇Te₄ – 36.5; Cu₅Te₃ – 28.5; Cu₂Te – 12.9; Cu_2.5SO₄(OH)₃·2H₂O – 16.2 and Cu₃(SO₄)(OH)₄ – 6.0 was used as an object of research. The physical and chemical research and technology experiments showed the fundamental possibility of commercial copper telluride processing by oxidative distillation roasting with the extraction of tellurium into a separate product. Air oxygen was used as an oxidant. It was established that a pressure decrease in the range of 80–0.67 kPa at the same temperature entails an increase in the degree of tellurium extraction. However, the tellurium extraction degree (93.0–98.0 %) at all pressures (within 1 hour) acceptable from the technology point of view is achieved at 1100 °C. Increasing the exposure to 3 hours has a minor beneficial effect. Diffractometric studies of cinders from technology experiments showed a decrease in the content of copper oxides in the pressure range of 80–40 kPa and an increase in the Cu3TeO6 phase content. With a subsequent increase in rarefaction from 40 to 0.67 kPa, there is a noticeable decrease in the amount of cuprite and, as a consequence, a sharp increase in the amount of cuprous oxide. A slowdown in the increase of the copper tellurate volume was noted at pressures of 40–20 kPa, and a sharp drop in its content at pressures below 13.3 kPa. The derived condensate is a free-flowing mixture of crystalline phases of tellurium dioxide (67.7 %) and tellurium oxysulfate (32.3 %). This condensate is a middling product for further production of elemental tellurium.

Nowadays, aluminum alloys with silicon are the most widespread construction materials. To increase the mechanical properties of aluminum alloys, modifying by Sr, Ti, and B are used. However, in the foundries, when using scrap and secondary aluminum alloys, the modifying elements are accumulated in alloys in the form of intermetallic particles that decrease castability. This is because of the modifiers have a short time effect and are not activated when remelting. Hence it is necessary to add the modifiers without reference to intermetallic particles that are exactly presented in the melt. This work investigated the effect of Sr, Ti, and B additions on A356.2 aluminum alloy fluidity obtained by vacuum fluidity test. It was shown that when AlSr10 and AlTi5B1 commercial master alloys are used (up to 0.3 wt.% Sr and 0.5 wt.%Ti), no fluidity decrease is observed. However, adding the same quantity of Ti with the homemade AlTi4 master alloy leads to a considerable fluidity decrease. With the help of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), the microstructure and phase composition of master alloys and A356.2 alloy after the addition of mentioned master alloys were investigated. Additionally, Thermo- Calc software evaluated the influence of modifier additions on alloy phase composition and phase transition temperatures. It was established that the influence of the modifier additions on the fluidity of the A356.2 alloy is connected with the shape and size of crystals that contained modifier elements in the structure of the master alloy. When the coarse crystals of that phases are present, these crystals’ incomplete dissolution is possible, inhibiting the free melt flow.

The study covers the effect of welding arc current (47, 57, and 67 A) on the structure and properties of deposited samples obtained by robotic electric arc surfacing. Sv-AK5 (ER4043) welding wire of the Al-Si system was used as a filler material. Surfacing was carried out on a substrate in the form of a 6 mm thick plate made of AMg6 alloy (Al-Mg system). During surfacing, a typical two-phase structure of a hypoeutectic composition is formed in samples typical for Al–Si alloys with a silicon content of 5 %. Along the height of deposited layers, there is a tendency to structure enlargement in the direction from the substrate, which is associated with the accumulation of heat in layers deposited along the height. As welding arc current increases, α-Al-based dendrites and eutectic silicon crystals are refined with an increase in the density and a decrease in the microhardness of deposited samples. The increase in density is due to the reduced proportion and size of gas pores, as well as refined structural components. The decrease in microhardness is associated with the increased proportion of the soft phase (α-Al dendrites) and decreased quantity of hard eutectic silicon crystals. The average content of silicon in samples deposited in three modes is in the range of 5.46–5.91%, which corresponds to the chemical composition of Sv-AK5 (ER4043) welding wire. Higher welding arc current contributes to an increase in the tensile strength and a slight decrease in the offset yield strength and relative elongation. The features of changes in the mechanical properties of deposited samples are determined by of the specific cast structure of deposited layers formed under conditions of directional solidification in the direction from the substrate.

The study covers the effect of the reduction ratio during cold rolling (εh) and the final annealing temperature of sheets rolled with different reduction ratios on the microstructure and the complex of mechanical and processing properties of cold-rolled sheets made of the V-1579 aluminum alloy of the Al–Mg–Sc system. It was established that as εh increases, the nature of plastic anisotropy changes slightly, and an increase in tensile strength and yield strength with a decrease in relative elongation is observed. In this case, the ultimate strength and yield strength anisotropy is practically absent. As the reduction ratio increases to 30–40 %, the relative elongation anisotropy increases, and its value in the rolling direction decreases more rapidly. However, after rolling with εh > 50 %, the relative elongation anisotropy practically disappears. Regardless of the annealing temperature, samples rolled with a higher reduction ratio have better strength properties. It was found that as the annealing temperature increases, the ultimate strength and yield strength decrease, and the relative elongation increases. In this case, softening with an increase in the annealing temperature occurs more intensively for samples rolled with a lower reduction. After annealing, the distribution nature of anisotropy indices in the sheet plane does not decrease and corresponds to the deformation type of textures for all analyzed modes. Moreover, the value of the in-plane anisotropy coefficient decreases in comparison with a cold-rolled sample. At the same time, processing properties of samples rolled with a higher degree of deformation after annealing are higher than those of samples rolled with a lower reduction, regardless of the annealing temperature.