The growing need for recycling, along with the depletion of high-grade ore concentrates, has led to the inclusion of previously accumulated technogenic materials — such as metallurgical slags, sludge from settling ponds of recirculating water systems, and similar waste – into the charge of primary smelting units. The share of such feedstock in the furnace charge now reaches approximately 25 %, which has resulted in serious technological disruptions to the stable operation of primary autogenous smelting units. In Vanyukov furnaces, this is manifested by the appearance – alongside the typical smelting products (matte and slag) – of a new atypical phase, the so-called intermediate layer. The formation of this layer leads to adverse effects, including the obstruction of flow paths from the furnace hearth to the slag and matte siphons, ultimately causing a complete shutdown of the unit. A sample of this abnormal product, collected from an industrial furnace during a period of process instability, was analyzed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). These methods allowed the determination of temperature ranges corresponding to phase transformations of the components comprising the intermediate layer. The results obtained can be used to define optimal parameters for stable smelting operation and to develop technical solutions that prevent conditions favorable for the formation of refractory accretions.

Infrared (IR) spectra were obtained for the surface layer of heterogeneous membranes — cation-exchange MK-40 and anionexchange MA-41P — widely used in electromembrane processes. Spectra were recorded for air-dry, statically water-saturated, and operational (dynamically water-saturated) membrane samples. Dynamic water saturation was achieved during the electrodeionization purification of a solution containing cobalt, copper, and cadmium ions. Water saturation was found to increase the intensity and bandwidth of the absorption band at ν = 3000÷3700 cm^–1, corresponding to the OH stretching vibration region. The appearance of an additional peak at ν ≈ 3287 cm^–1 was attributed to the formation of stronger hydrogen bonds in the membrane pore space. The absence of shifts in the absorption bands corresponding to the membrane matrix components under air-dry, statically, and dynamically saturated conditions indicates their chemical stability. In the MA-41P membrane, after use in electrodeionization, changes were observed in both the intensity and position of absorption peaks in the ν  1220÷1000 cm^–1 region, associated with the functional groups of the anion exchanger. The observed spectral changes were evaluated by calculating the normalized peak intensities of the absorption bands. It was shown that in the dynamically water-saturated state, both MK-40 and MA-41P membranes exhibit a reduction in the amount of weakly bound (“free”) water and the formation of stronger hydrogen bonds. The results of optical density calculations for characteristic polyethylene absorption bands — the main component of the membrane matrix — are presented. Changes in optical density upon water saturation indicate conformational rearrangements of polyethylene macromolecules. The amounts of chemically unbound solute components retained within the membrane volume were quantified; these species do not affect the membranes’ chemical stabiliy or operational performance.

This study continues the research presented in our previous article [1], which examined the process of gold adsorption from gold cyanide solutions onto activated carbon (AC) over a relatively short time interval – up to 40 h – during which adsorption occurred predominantly within the near-surface layer of the sorbent. The aim of the present work was to improve the previously developed mathematical model of gold adsorption onto activated carbon from gold cyanide solutions [1] by incorporating the intraparticle mass transfer stage into the model. This goal was achieved by adding an additional term to the adsorption kinetics equation that accounts for gold sorption driven by intraparticle mass transfer. This modification preserved the entire theoretical framework of adsorption described by the earlier kinetics equation, incorporating it as a special case within a more general sorption model based on the improved kinetics equation. An analytical solution to the modified equation was derived, from which a new-type adsorption isotherm was obtained in analytical form. The paper presents the derivation and analysis of this new-type isotherm equation and its identification based on experimental data.

This study focuses on investigating the possibility of selective separation of palladium (II) from solutions containing non-ferrous metals and iron by sorption onto chemically modified silica. The study used both individual (single-metal) and model multicomponent solutions. The sorbents included silicas functionalized with iminodiacetic acid (IDA-D), phosphonic acid (PA-D), and aminomethylphosphonic acid (AMPA-D) groups, as well as a well-known chemically modified silica bearing grafted γ-aminopropyltriethoxysilane (APTES) groups at a grafting density of 1.63 mmol/g. Under static conditions at room temperature, the time required to reach equilibrium sorption values for Cu(II), Ni(II), and Fe(III) ions – typically present in process solutions – was determined for the IDA-D, PA-D, and AMPA-D sorbents. Sorption dependencies on hydrochloric acid concentration were established for these metal ions. For IDA-D, the effect of halide ion concentration on sorption was also studied. It was shown that these ions are sorbed in weakly acidic media but not in 1–2 M HCl, and that sorption capacity decreases in the order: IDA-D > AMPA-D > PA-D. However, the conclusion that quantitative separation of Pd(II) from base metal ions could be achieved using these complexing sorbents (exemplified by IDA-D) under dynamic conditions was not confirmed. The sorption behavior of Pd(II), Cu(II), and Al(III) ions was also examined under static and dynamic conditions using the APTES-functionalized silica and chloride and chloride-bromide solutions, including model solutions simulating leach liquors generated from the treatment of spent catalysts for low-temperature carbon monoxide oxidation. These solutions contained 0.004–0.015 mol/L Pd, 0.014–0.049 mol/L Cu, and 0.015–0.060 mol/L Al. The results demonstrated the feasibility of selectively separating Pd(II) from leach solutions of spent catalysts using this sorbent. A processing scheme was proposed, comprising sorption from 0.1 M HCl, water rinsing of the loaded sorbent, and elution of Pd(II) with a 5 % thiourea solution in 0.1 M HCl. It was shown that separation of palladium from non-ferrous metals occurs already at the sorption and washing stages.

The study addresses the problem of predicting the grain structure in large-scale castings made of the VZhL14N-VI nickel-base superalloy, which are bodies of revolution with very thin walls. To this end, the ProCast casting simulation software was used, including its CAFE module for grain structure prediction. Cooling rates in various areas of the casting were determined by computer simulation. Grain size measurements were then performed on real samples produced under industrial conditions at PJSC UEC Kuznetsov (Samara, Russia), and the correlation between grain size and cooling rate was established. It was found that grain size is affected not only by the cooling rate, but also by the geometric features of the casting, particularly its thermal modulus (according to Chvorinov’s rule). The results show that ProCast can be effectively used to predict casting defects in large-scale castings made of nickel-base superalloys. A comparison of the temperature-dependent density, specific heat capacity, and thermal conductivity of the VZhL14N-VI alloy – obtained through both direct measurements and ProCast thermodynamic database calculations – showed that the computed data are sufficiently accurate for use in casting process simulations. The CAFE module was found to be applicable for predicting grain structure in castings; however, accurate simulation requires the specification of key parameters, primarily the degree of undercooling during solidification and the number of grain nuclei in the alloy. Since these parameters cannot be measured directly, further research is required to determine them.

Antifriction tin bronzes are used in the aerospace industry to manufacture components that operate in friction assemblies at elevated temperatures. This is due to the alloy’s favorable combination of antifriction, mechanical, and corrosion properties. In particular, tin bronze C92900 (alloy Cu–10Sn–3Ni–2Pb (wt. %)) is widely used in such applications. It is employed in the production of braking system components and plunger pump parts. Currently, these parts are manufactured by machining ingots produced through casting with directional solidification. However, this method has a low material utilization rate, typically between 5 % and 15 %. The most promising method for producing C92900 ingots is upward continuous casting technology, which allows the ingot dimensions to closely match those of the finished part. This significantly reduces machining effort and increases metal utilization to 95 %. This study presents the results of process development for the upward continuous casting technology of 15 mm diameter C92900 ingots. The structure and properties of the castings were also investigated. It was shown that as the casting speed increased from 90 to 360 mm/min, the volume fraction of the γ-Cu₃Sn intermetallic phase increased, while the amount of tin-based solid solution remained nearly unchanged. At the same time, the phase distribution became more refined. The macrostructure consisted of columnar and equiaxed grains. As the casting speed increased, the columnar grains became more tilted relative to the direction of heat removal. The hardness increased from 127 ± 2.73 to 136 ± 4.25 HB, and the tensile strength and elongation slightly increased up to 250 mm/min, then decreased at 360 mm/min, which was associated with the macrostructure approaching a transcrystalline form. The study also examined shrinkage cavities and segregation defects in ingots cast at 150 mm/min and analyzed their causes. Finally, the paper provides recommendations for optimal casting parameters for 15 mm diameter ingots produced by upward continuous casting technology

This study investigates non-ferrous metallurgy waste – specifically, the clay fraction of zircon-ilmenite ore gravity separation tailings (ZIGT) – with the aim of using it as both a clay component and a non-plastic additive (chamotte derived from ZIGT) in the production of acidresistant ceramic tiles. It was found that samples made solely from ZIGT (without any additives), fired at temperatures of 1250–1300 °C, do not meet regulatory requirements for acid resistance. Introducing 40 wt. % chamotte into the ceramic body was found to be optimal for producing acid-resistant tiles at 1300 °C that comply with all requirements of GOST 961-89 Acid-Resistant and Thermo-Acid-Resistant Ceramic Tiles, grade KSh (chamotte-based acid-resistant tiles). Increasing the chamotte content beyond 40 wt.% reduces the clay binder fraction, which in turn lowers the plasticity index (to below 11), causing cracks to form in the samples during shaping. The phase composition of four tile samples with varying ZIGT and chamotte contents was analyzed. X-ray diffraction patterns of the samples fired at 1300 °C revealed prominent peaks corresponding to mullite, cristobalite, quartz, and hematite, which were also confirmed by IR spectroscopy. The formation of mullite is crucial in the production of acid-resistant ceramics, as mullite is the primary phase determining the operational properties of the material. As a result, new ceramic compositions were developed and acid-resistant tiles were obtained from non-ferrous metallurgy waste without the use of conventional natural raw materials.