The paper considers research findings on sands from the high-clay alluvial compound complex deposit of the Fadeevsky ore-placer site characterized by high sand strength characteristics and by an elevated content of small fractions of valuable components. The paper describes an energy-dispersive microanalysis of rock samples. The samples contain trace elements of a wide range of noble (including gold, silver, and platinum), rare-earth and other elements. It was established that sands from the gold-bearing placer under study constituted a rather complex object for disintegration. Acoustic characteristics of sands under study in their original state and after water saturation were determined experimentally and analytically. They indicate a significant exceedance of the proportion of shear modulus maximum values. In order to solve the microdisintegration problem for the purpose of extracting small and fine gold by more environmentally and technologically efficient means, the paper proposes to use systems based on processes of cavitation-acoustic influence on the mineral component of the slurry.

For the purpose of improving the accuracy of obtained results, the paper compares two methods for studying wetting and spreading processes upon a solid substrate. The first method utilizes liquid droplets, and the second method utilizes bubbles. When spreading, the shape of droplets and bubbles changes, and this can be assessed quantitatively only by the Laplace equation, though the equation is applied only in the case of bubbles (the second method). For the first method, this excludes control over surface cleanliness of the spreading droplet. The effect of micropollution on the results is considered on the basis of precise calculations carried out for both methods. The paper calculates spreading curves for nanobubbles with initial diameters of 20 and 10 nm on substrates with different wettability, where the wettability is assessed not by the numerical value of the contact angle, but by easily realized samples of such  substrates Г, Ф and Нх corresponding to the contact angle, where х is the fraction of the surface under the bubble, covered with molecules of the ionogenic collector: 0,8; 0,6; 0,4, and 0,2. The spreading curves clearly illustrate the range of possible spreading of nanobubbles, from the limit spreading on the substrate Г to practically zero spreading on the substrate Ф, as well as energy sources of the spreading process and causes of their depletion. The informational value of spreading curves is preconditioned by the fact that more than ten parameters of the bubble and the substrate are used in their calculation. When using reagents, activation of the flotation process can spread to larger bubbles.

The paper presents results obtained in the analysis of thermodynamic properties and research findings on kinetic regularities of the leaching process of a new type of sulfated copper-zinc middlings formed when removing sulfide materials which cannot be effectively filtered out by flotation. Analysis of kinetic curves shows that for any acid concentration in the range of 0–20 g/dm³, the reaction rate at the start time (30 min) differs markedly from the subsequent period. At the start time the rate is controlled only by external diffusion, and after 30 minutes of the process time the kinetic hindrances begin to occur. The paper determines the order of cinder leaching reactions: 1,0±0,1 for copper, 0,87±0,1 for zinc, 0,56±0,1 for iron. The results of calculating the apparent leaching reaction rate constant showed its weak temperature dependence, which correlates well with thermodynamic analysis data.

The accumulation of arsenic in solid, liquid and gaseous waste of metallurgical production is an acute problem. Deposition of arsenic by sodium hydrosulfide is an effective and fast method of arsenic removal from solutions. The paper proposes a reactor design procedure for extraction of As (III) using the sulfide technology from washing solutions for wet gas scrubbing in sulfuric acid production. The paper takes into consideration the optimum parameters for removal of arsenic from solutions: the specific consumption of sulfide sulfur per1 kgof arsenic, the concentration of As (III) ions in the solution, the rate of sodium hydrosulfide feeding into the solution, and the hydrodynamic regime of the reactor. The obtained results are useful for design of experimental-industrial reactors used in dearsenication of solutions.

The paper describes the thermodynamic simulation of chemical and phase transformations in the Fe2O3–NiO–CoO–C system carried out using the Astra 4 multipurpose software package developed at the Bauman Moscow State Technical University, which was designed to simulate equilibrium states and processes in high-temperature systems with chemical and phase transformations. The study of chemical and phase transformation simulation in the system was carried out in temperature ranges of 573–1773 K and pressure ranges of 0,001–0,1 MPa. In the course of simulation it was found that iron mainly transited into Fe(k) and its transition degree (αFe) was from 28,9 % at Т = 1173 K to 99,05 % at Т = 1773 K; the value of αNi was 100 % at Т = 573÷1273 K and decreased to 99,99 % (when starting transition into the gaseous phase) when the temperature increased to 1773 K; the transition degree of cobalt (similar to nickel, it was distributed into Со(к)) was 100 % at Т = 573÷1273 K and decreased to 99,99 % (when starting transition into the gaseous phase) when the temperature increased to 1773 K.

The paper demonstrates the possibility of increasing the efficiency of gas scrubbing systems in aluminum production by improving technologies for trapping and treatment of liquid and solid waste. The paper proposes a non-waste process of «wet» gas scrubbing waste recycling, which makes it possible to obtain fluoroaluminates with a cryolite module of no greater than 1,8–2,0. During treatment of gas scrubbing solutions the optimum ratio of fluoroaluminium acid to sodium fluoride is 14 : 9 (g/kgН₂О), which ensures the most complete bonding of aluminum fluoride ions into regeneration products. The pH interval 5Al3F14 (admixed with AlF3), with structural transition from the chiolite to the cryolite Na3AlF6 occurring at pH = 4÷6. This cycle provides for the simultaneous production of aluminum sulfate and carbon concentrates, non-waste treatment of fluoride-alumina slurries, and the use of carbon dioxide in processes of neutralization and treatment of sewage. The paper calculates optimum parameters which ensure emission reduction and improve the balance of components when introducing the «dry» gas scrubbing into a combined (parallel and sequential) scheme of gas scrubbing and regeneration facilities.

The paper studies sorption of aluminum and gallium in the form of hydroxocomplexes on the AN-31 weak-basic anion-exchange resin at a temperature of 298 K from standardized test solutions. On the basis of experimental data the paper determines forms of ions sorbed by the solid phase of the anion-exchange resin. Sorption of pentahydroxoaluminate and pentahydroxogallate ions occurs in the Stern-Helmholtz layer. The paper calculates values of apparent constants and Gibbs energies of ion-exchange equilibrium. The obtained values for the full exchange capacity of gallate ions equal to 55–58 g/kg under static conditions cause the use of the AN-31 anion-exchange resin in the concentration of gallium ions from alkaline aluminate solutions.

Lost foam casting (LFC) is currently one of the most effective and promising methods to produce high-quality thin-walled castings that exhibit a desired dimensional accuracy, the required surface roughness, and other properties. This technology is widely used in the manufacture of aluminum alloys products. In order to ensure cost minimization in the manufacture of products and the production of quality castings, it is advisable to use an increased amount of recycled material in the charge, paying attention to the overheating temperature and the melt holding time. The paper presents research findings on temperature regimes of melting and casting of aluminum alloys during LFC. Under the concerned industrial conditions, the following regimes were most effective to ensure the best quality indicators of leak-tight castings with respect to dimensional accuracy and surface roughness: melt overheating temperature – 880÷890 °С, pouring temperature – 820÷830 °С. The paper studies the effect of different temperature parameter options for melting and casting of the AK7 melt composition during LFC on the content of nonmetallic inclusions in the as-cast state. It was found that the minimum content of γ-Al₂O₃ in the finished alloy was provided by the melt overheating temperature up to 880÷890 or 940÷950 °С, and the pouring temperature of 820÷830 °С.

An increase in the sum of alloying elements in industrial silumins causes excess intermetallic phases to form in their structure. When the amount of modifiers introduced into such alloys exceeds a certain amount, structural components coarsen due to overmodification, which may cause deterioration of mechanical properties of cast alloys. As the amount of alloying elements in alloys increases from 7,35 % (АК7ch) to 14,3 % (АК10М2N), the optimum consumption of the modifying microcrystalline remelt decreases from 0,6 to 0,3 wt.%. The optimum amount of introduced titanium is reduced from 0,05 to 0,01 % when using the AlTi5 master alloy and from 0,02 to 0,01 % when using the AlTi5B1 master alloy. With an increase in the silicon content, the modifying effect of the AlSr10 master alloy is enhanced, while the amounts of strontium introduced into alloys are smaller. The paper demonstrates that metallic modifier consumption depends on its modifying property, as well as on the sum of alloying elements in the modified silumin.

The paper considers pressing methods for prismatic and screw-shaped metal sections. An example of cold pressing of a M4 copper billet to produce a solid square section making is provided. The paper compares traditional pressing (extrusion) and extrusion with subsequent pressing and torsion (extrusion and screw pressing) with regard to mechanical characteristics, energy intensity and fracture pattern of copper samples. At the same time, extrusion and screw pressing of a billet was carried out in one device within one process operation. Bulk copper billets ∅11,7×60 mm were subjected to prismatic and screw-shaped section pressing in one pass at the room temperature. A hydraulic press was used for billet pressing with a punch. Solid copper prismatic and screw-shaped sections with a square section of 8×8 mm were obtained following the deformation processing. The paper presents findings on mechanical properties, deformation regularities, and the fracture mechanism during monoaxial stretching of M4 commercial copper samples in the as-delivered and as-hardened states. Mechanical tests for monoaxial stretching of samples with working dimensions of ∅3×15 mm was made using the UTS-20k testing machine at a constant loading rate of 3,33·10^–5 m·s^–1. A certain strength improvement of copper extruded in one pass at a room temperature was found. Screw pressing after extrusion ensures a higher ductility as compared to the original state and extrusion. The paper describes a fractographic investigation of fractures in samples using the Hitachi TM 3030 scanning electron microscope in the secondary electron mode. The paper demonstrates that the fracture mechanism of copper samples in the as-delivered state, as well as following the extrusion and extrusion and screw pressing, is qualitatively the same. Fracturing of M4 copper samples both in the original state and following deformation processing under the indicated regimes occurred by a mechanism of ductile fracture. It was found that copper subjected to extrusion and screw pressing featured greater energy intensity due to higher ductility. The fracture in the fibrous area of the sample subjected to extrusion and screw pressing is notable for the tiered arrangement of pit blocks. Large pits and micropits in all copper states are present both in the fibrous area and in the peripheral area of the cut.