The paper suggests a method for recovering contaminants from aluminum-production waste called sweepings to return them further to the electrolytic cell. It is proposed to use the grinding – sizing – reverse flotation – thickening scheme for material beneficiation. Flotigam 7266 (Clariant, Germany), a mixture of primary fatty alkylamines, was used as a flotation reagent in the study to completely remove silicon and iron oxides. The combination of pine oil mixed with kerosene was used to remove carbon particles. Flotation was conducted on the FML 0,3 flotation machine. The raw material, chamber product and tailings were analyzed for the content of carbon and aluminum, iron and silicon oxides using X-ray diffraction, X-ray phase and chemical analysis. It was found that processing the overall mass of the material does not provide a product with an acceptable content of silicon and iron oxides. Based on the X-ray phase analysis of various raw material fractions it was proposed to process material fractions containing minimum contaminants (carbon, silicon and iron oxides). Two fractions were chosen for flotation processing: –0,071 mm and +5,0 mm according to the X-ray diffraction analysis of various material fractions. Processing the first fraction allowed obtaining the chamber product of an acceptable quality. The coarse electrolyte-containing fraction (+5,0 mm) provided the product with the high content of alumina and fluorinated components and low content of carbon and iron oxide, but with a significant amount of silicon oxide. Further use of this product is possible to obtain silicon-aluminum alloys.

This paper studies the results of investigating oxidation kinetics of pellets from copper concentrate produced by Gaisky GOK under conditions of controlled convective heat and mass exchange at the minimum radiation component of heat transfer between heated (450–700 °С) gaseous oxidant (air) and pellets. It was found that as the air consumption increases, the initial oxidation decelerates though theoretically it was proved that the oxidant contact with pellet surface does not limit the process. The paper includes formulas deduced by the author for calculating the period of pellet heating up to temperature of initial oxidation and heated air. It was determined that the higher mechanical strength of pellets decreases the speed and completeness of pellet oxidation. The positive effect of increased oxidant (air) consumption on the oxidation speed due to the lack of external diffusion slow-down is explained by a shorter pellet heating period. Experimental activation energy (Е = 155,1÷337,1 kJ/mole) is typical for kinetic or transition mode at 450–500 °С and pellet strength 718,1 and 932,0 N, and for diffusion mode (E = 33,3÷57,4 kJ/mole) at 500–700 °С. The ratio of efficient diffusion in active layer pores was calculated for an isometric part of the kinetic curve at 600 °C. The indicated part shows Knudsen diffusion.

The paper provides the results of studying the influence of preliminary thermal treatment of crushed electronic waste at a temperature of 450 °C on the copper extraction degree during subsequent material leaching by nitric acid solutions. Electronic industry waste, in particular automobile microcircuits and computer printed circuit boards, was chosen as a research object. It was experimentally determined that the percentage of the organic phase in the research object composition varies within 20–25 % of the crushed raw material mass. The results of thermogravimetric analysis (TGA) and X-ray fluorescence analysis (XRF) show that the maximum degree of organic removal and formation of metal oxides are observed in a temperature range of 400–450 °C. A mathematical model of copper leaching from electronic waste by HNO3 solutions was obtained. The optimum parameters for the process were found – the temperature in the system is 75 °C; leaching duration is 150 min; acid concentration is 4 M with a maximum copper extraction to the solution of 98 %. A comparative analysis of leaching processes for two types of materials (after thermal treatment and without it) was carried out. It was experimentally confirmed that copper leaching from electronic waste by nitric acid solutions with lower concentrations is more complete for materials after preliminary thermal treatment as compared to raw material leaching without thermal treatment. It was proved that preliminary thermal treatment leads to phase changes in the composition of the research object, namely, the transition of metals to their oxide forms, which positively affects the degree of copper extraction from electronic waste at subsequent nitric acid leaching.

The paper provides the method developed by the authors to produce low-arsenic crude antimony from the antimony concentrate containing 47,77 of Sb and 0,17 % of As. The basis of the concentrate is sodium hexahydroxoantimonate or mopungite mineral. Concentrate reduction with coke according to the traditional technology produced crude antimony with a high arsenic content – 0,34 %. To reduce arsenic content in crude metal to 0,1 % and eliminate a separate stage of antimony refining from arsenic, reduction melting is proposed in the presence of sodium plumbite or lead oxide. This allows obtaining crude antimony with an arsenic content of 0,07–0,1 %. The process of antimony concentrate reduction melting on crude antimony was carried out in an oven with silicon carbide heaters in alundum crucibles with charge batches 100–150 g each. The content of base metal and impurities in crude antimony was determined by chemical and atomic absorption methods. The form of arsenic in the concentrate was determined by X-ray phase analysis using the DRON-3 automated diffractometer (CuKα radiation, β filter). Arsenic concentration in the slag phase in the form of Pb2As2O7 lead diarsenate is shown. Thermal gravimetric analysis was performed for reduction melting of charge consisting of antimony concentrate, lead oxide and coke and it was found that metal antimony formation occurs in a temperatures range of 445–950 °C.

Conscious management of metal crystallization processes in order to obtain a defined ingot microstructure is provided by using various physical fields. These fields affect the melt and change its internal state, and therefore its crystallization kinetics. The paper describes the thermodynamics and kinetics of aluminum crystallization when the melt is treated with magnetic field. A quite simple experimental setup is created to allow studying the magnetic field effect on molten aluminum or other metals and alloys. It consists of several main components: (1) electrical furnace; (2) water-cooled copper crucible combined with an electromagnetic coil; (3) mechanical device for rapid movement of the aluminum melt crucible; (4) system for melt temperature monitoring and control and (5) electronics for data recording and processing. It is experimentally proved that magnetic field changes the melt-crystal phase equilibrium temperature, latent heat of phase transition and temperature of melt supercooling at crystallization. It is shown that changes in these parameters reduce the radius of critical nuclei and increases the speed of their origin. Temperature-time relationship are obtained for the crystallization process. It is experimentally proved that aluminum melt treatment with magnetic field reduces the time of crystallization. The analysis of aluminum samples obtained under the influence of magnetic field has shown that their structure has more fine grains compared with untreated samples.

The paper demonstrates the urgency of studies focused on creating new Al-Mg alloys doped with scandium and featuring by an advantageous combination of operational and mechanical properties such as weldability, corrosion resistance and sufficient strength. In production conditions, 560×1360×4520 mm flat ingots were obtained from an experimental scandium-containing alloy. They were cut into billets with a maximum thickness of 40 mm and then heat treatment and sheet rolling modes were developed for them and tested. The DUO 330 mill with smooth rolls having an initial diameter of 330 mm and a barrel width of 540 mm was used as rolling equipment. Experimental studies consisting in blank preparation for rolling (homogenization annealing and face milling), hot rolling at 450 °C, cold rolling to a thickness of 3 mm and annealing of cold-deformed semi-finished products at 350 °C for 3 hours allowed making deformed semi-finished products by various drafting patterns at rolling that were subjected to heat treatment. The maximum total degree of deformation during billet rolling to the 3 mm thickness was 92,5 %, and the draw ratio per pass changed from 1,04 to 1,2. The LFM400 400 kN universal test machine as per GOST 1497-84 was used to determine mechanical properties of deformed and annealed semi-finished products of various thicknesses made of an experimental alloy and identify regularities of their changes depending on the total degree of deformation during rolling. It was found that when rolling strips of an experimental scandiumcontaining aluminum alloy the ultimate tensile strength and yield strength of the metal grow, and the percentage elongation decreases with an increase in the total degree of deformation. This corresponds to the general ideas of metal forming theory. The mechanical analysis of semi-finished products showed that the level of strength and plastic properties is quite high, wherein the ultimate tensile strength reaches 453–481 MPa, yield strength – 429–457 MPa, and percentage elongation – 3,8-5,0 % for cold-deformed samples. Annealing made it possible to increase percentage elongation values to 14–16 % at sufficiently high yield strength (up to 277 MPa). The results of the conducted studies were used to develop casting, rolling and annealing modes for making semi-finished products of the Al–Mg alloy sparingly doped with scandium within 0,10–0,14 % that will be used when mastering machining technologies in production.

Calculation methods and Thermo-Calc software were used to analyze isothermal sections of the Al–Fe–Si–Zr alloy diagram at 450 °C and 600 °C, and polythermal sections at the concentrations of silicon up to 2 wt.% and zirconium up to 1 wt.%. It has been shown that a favorable phase composition consisting of an aluminum solid solution (Al) and an Al8Fe2Si phase with zirconium contained in a solid solution (Al) can be achieved under equilibrium conditions when making a cast section at silicon concentrations of 0,27–0,47 wt.%. In order to implement the process under non-equilibrium conditions of the abovementioned structural components and to ensure Zr inclusion in the (Al) composition, test ingots were made at an increased cooling rate (over 10 K/s). The metallographic analysis of the sample cast structure revealed the desired structure at 0,25 wt.% of Si and 0,3 wt.% of Zr in the alloy. The Al–1%Fe–0,3%Zr–0,5%Si alloy microstructure also contains the (Al) + Al8Fe2Si eutectic, but it is observed that the Al8Fe2Si phase is partially transformed into Al3Fe in step annealing at 600 °C. The structure of the alloy with 0,25 wt.% of silicon in the T600 state contains fragmented particles of the (Al) + Al8Fe2Si degenerate eutectic along the boundaries of dendritic cells. It has been found that the Si : Fe = 1 : 2 ratio in the alloy has a positive effect on its mechanical properties, especially hardness, without any significant conductivity reduction in the annealing process. This effect is explained by compact morphology formation in the structure of Al8Fe2Si phase particles. Moreover, silicon accelerates solid solution decomposition in terms of zirconium, as shown by the experimental graphs of hardness and resistivity dependence on the annealing step. Using the optimization function for the given hardness and resistivity parameters, the Al–1%Fe– 0,3%Zr–0,25%Si alloy demonstrated the best set of properties in the T450 state.

Calcium is one of the most common and, therefore, cheap metals on earth. It has long been used for the modification and alloying of heavy metal alloys, in particular lead and copper. As a modifier, it is used in cast irons and steels. More recently calcium started to be used in light alloys based on aluminum and magnesium. This review covers the applications of metallic calcium, its effect on the structure and properties of various alloys. Over the past few years, systematic studies of aluminum-calcium-eutectic alloys have been carried out and it has been found that their casting properties are no worse than that of silumins, and they can be subjected to hot and cold rolling with a high degree of deformation. Threefold and more complex phase diagrams of systems including calcium were constructed, and multicomponent alloys based on them were investigated. All this allowed us to distinguish several groups of new promising calcium-containing aluminum alloys: (1) alloys hardened without quenching due to nanosized Al3Zr, Al3Sc and Al3(Zr,Sc) phase particles precipitated during annealing; (2) high-strength alloys doped with traditional hardening elements of aluminum solid solution, zinc and magnesium; (3) composite-type alloys containing more than 20% of eutectic intermetallics in their structure. These alloys have a reduced density, an improved set of performance properties, increased corrosion resistance and high manufacturability when making cast and deformed semi-finished products.