This paper presents the results of experimental and numerical studies of the casting process of 99.85% pure aluminum using investment-casting technologies with patterns produced by additive manufacturing. The influence of pouring temperature, mold-filling time, and gating-system design on porosity formation and casting quality was analyzed. It was established that increasing the pouring temperature within the range of 700-800 degrees C leads to increased porosity due to higher gas solubility and intensified turbulence of the melt flow. It was shown that the separating gating system ensures a minimum number of defects compared to top and bottom metal-feeding systems. In addition, thermal analysis of PLA and a glass-fiber-reinforced PLA composite was carried out. Pure PLA was found to burn out almost completely (residue about 2.4%), whereas the composite was characterized by a high residual content (similar to 43.6%), which may negatively affect mold quality. The simulation results obtained using the AutoCAST software package showed good agreement with the experimental data and confirmed the effectiveness of numerical modeling for optimization of casting processes. It was established that the optimal pouring-temperature range for aluminum is 720-760 degrees C. The obtained results confirm the potential of using PLA in investment casting technology and make it possible to improve the quality of aluminum castings under industrial production conditions.
Purification of lanthanum chloride from high-load zinc contaminants remains a major challenge in producing grade 5N lanthanum oxides. This study investigates the process of matrix-driven solvent extraction using tertiary amine N235 to treat a 1.41 M rare earth oxides (REO) industrial lanthanum chloride feed containing 3000 mg/L zinc. Thermodynamic modelling with Medusa Hydra and Langmuir isotherms revealed that the high chloride activity (> 4 M) of the matrix induced significant changes in coordination towards the extractable [ZnCl4](2-)complex. This transition has a spontaneous Gibbs free energy of-14.68 kJ/mol. While the two-stage countercurrent flow sheet meets the industry target of less than 50 mg/L zinc, the five-stage configuration achieves a four-log reduction to 0.23 mg/L, effectively achieving 99.999% purity. This reagent's lean approach, using water-induced stripping, offers a sustainable and mathematically validated framework for ultra rare earth finishes.
The article presents the results of a qualitative analysis of circuits of autonomous current and voltage inverters with cut-off valves. The influence of the charge on the switching capacitor in parallel and series equivalent circuits on the restoration of the switching properties of the thyristors in the inverter power circuit is studied. It is shown that, due to the energy periodically accumulated in the inductive elements of the load, the voltage across the switching capacitor in the cut-off state is higher than in a conventional parallel autonomous current inverter. This ensures increased switching stability of the inverter. Consequently, the circuit of an autonomous current inverter with cut-off valves remains operational in valve converters for variable-frequency electric drives and maintains performance during sudden load surges and short circuits, since the voltage on the switching capacitor does not depend on the load voltage. Thus, the charge on the switching capacitor is preserved even when the load voltage drops sharply between thyristor commutations.
Addressing corrosion and wear in assemblies, components, machine parts, and equipment operating in aggressive environments under severe wear conditions remains a pressing challenge and continues to draw focused scientific attention. This work aimed to investigate how the key magnetron sputtering parameters (working pressure, plasma current, and process-gas flow rates) affect the surface morphology, microstructure, and composition of TiN and CrN films deposited under different conditions. Microstructural analysis revealed that, across the investigated parameter window, the films exhibit a columnar cross-sectional architecture and a smooth surface morphology with no visible defects, showing no pronounced differences between the deposition regimes. After 30 min of deposition, the film thickness ranged from 0.17 to 0.46 mu m for TiN and from 0.59 to 3.46 mu m for CrN, depending on the sputtering conditions. The results demonstrate that plasma current and working pressure have a strong effect on film thickness and chemical composition, whereas variations in the working-gas flow rate exert a coupled influence on thickness, microstructure, and the stoichiometry of TiN and CrN layers. Elemental analysis further indicates that increasing the pressure to 0.65 Pa increases oxygen incorporation in the films. During chromium sputtering, raising the plasma current to 1.5 A leads to film delamination. For TiN, a balanced regime with a moderate N2 flow is preferable, providing a reasonable growth rate and a composition close to stoichiometric. For CrN, the range of stable operating conditions is substantially broader, and the process parameters have a more pronounced impact on its structure and composition. These findings can support the design of TiN/CrN wear-resistant multilayer coatings produced by magnetron sputtering for protecting machine parts and equipment against wear and corrosion.
This study focuses on the solid phase extraction of biogenic amines (BAs) using a sol-gel adsorbent immobilized with a hydrazone ligand, named 2-hydroxy-5-nitrobenzaldehyde-2,4-dinitrophenylhydrazone. The hydrazone compound was synthesized and characterized through Fourier Transform Infrared Spectroscopy (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The efficiency of the sorbent material for extracting BAs was evaluated using the solid phase extraction (SPE) method. Key experimental parameters affecting BA extraction, including pH, equilibrium time, ligand concentration, and biogenic amine (BA) concentration, were systematically investigated. The results indicated a strong recovery of BAs from aqueous samples, demonstrating a significant affinity between the sol-gel matrix containing the hydrazone ligand and the target analytes. The findings demonstrate that incorporating the hydrazone ligand resulted in a marked enhancement of extraction efficiency at a concentation of 17 & times; 10(-3) M. Notably, the method exhibited high selectivity for aliphatic biogenic amines such as putrescine (PUT), cadaverine (CAD), and spermidine (SPD). This extraction method was successfully applied to food samples, yielding good recovery rates.
Through a comparative analysis, this study investigates the development, simulation, and application of mathematical models for integrated analysis of copper rod production in order to improve product quality, reduce costs, and minimize risks. The purpose of this article is achieved by creating mathematical descriptions of real processes, which are then used to conduct computer experiments. In contrast to the traditional molecular dynamic methods, this study used information technology to obtain the characteristics of the flow field in technological equipment. The novelty lies in: integration of thermomechanical modeling with an optimization algorithm; introduction of a criterion minimizing mechanical property variation; consideration of reduction and redistribution effects on roll wear; possibility of adaptive real-time control. An information analysis of the profiles of copper melt flow velocities in a wide range of temperatures in the Copper Rod Production Plant Kazkat is presented. Information Technology fulfils the need to address the problem of determining the optimal values of temperature, rolling speed, and other parameters to achieve the best quality and productivity of copper rod production processes. Based on these findings, this study proposes the optimization directions for the temperature field profile in the rolling rolls, which leads to a decrease in roll wear and an increase in the uniformity of the wire rod structure, focusing on improving microstructural properties.
In this scientific article, the material composition and microstructure of the sample obtained from the Shargun coal deposit were studied based on complex instrumental methods. Based on the conducted research, the elemental composition was determined using an AL-NP-5010A X-ray fluorescence spectrometer, and microscopic analyses were carried out with an increase of up to 1600 times. The spectrometric analysis showed that the high intensities of silicon and aluminum are due to the high proportions of kaolin and quartz, which are aluminosilicates. Also, the detection of iron, calcium, and sulfur indicated the presence of additional sulfides in the iron and carbonate phases. Based on the results of microscopic analyses, it was established that the coal sample has a heterogeneous and porous structure, and the mineral inclusions within the organic matrix are located in a dispersed and clustered state, characterized by micro porousness. At the same time, the proportion of the mineral phase area according to the morphometric assessment was 18-27%, and the micro-porousness coefficient was in the range of 0.12-0.20. It was observed that the angular shape of the particles and the polydisperse granulometric composition correspond to the Rosin distribution. From the integral analysis of the obtained results, it was established that the high content of aluminosilicates and iron oxides increases the susceptibility to ash formation and slagging processes. Also, the presence of porous microstructures and microcracks made it possible to increase the reactivity of the process of heat treatment and gasification.
The article is devoted to the development of a methodology for microstructural and thermal verification of the quality of an industrial Ti-10V-2Fe-3Al triple vacuum arc remelted ingot produced by UK TMP JSC. It was established that all zones of the ingot demonstrate a two-stage thermal evolution characteristic of the beta-metastable Ti-10V-2Fe-3Al alloy: decomposition of the metastable beta phase (approximate to 520-570 degrees C) and an endothermic alpha ->beta phase transformation (approximate to 950-1120 degrees C). It was found that the enthalpy of the exothermic decomposition of the beta matrix increases by approximately 60-80% in the lower zone of the ingot. The width of the phase transition (Delta T) correlates with an increase in microsegregation. It was also determined that the enthalpy of the endothermic alpha ->beta transformation decreases from the bottom part of the ingot toward the steady-state crystallization zone (Middle-1), which correlates with a reduction in the microsegregation parameters obtained from SEM-EDS profiles (Delta C_max, sigma C, L-corr). Thus, thermal analysis confirms the absence of a pronounced vertical gradient of structural stability and can be used as a validating criterion for the integral electrode quality index. For the first time, a quantitative correlation between SEM-EDS profiles and DSC-DTG characteristics has been proposed. Thermal analysis is suggested as an independent validator of microsegregation. An approach to the quantitative evaluation of microsegregation based on SEM-EDS profiles using the parameters Delta C_max, sigma C, L-corr,L- and Delta CO(local) has been developed. Additionally, the use of an integral chemical index I(che)m, and a critical threshold I-chem(crit) is proposed for electrode quality control using thermal analysis results.
In this article, rhenium's distinct physicochemical characteristics, which make it essential for petrochemistry, electrical technology, rocket and aviation engineering, and the manufacturing of catalysts and high-precision tools, account for the metal's rising demand. The main source of rhenium at JSC "Almalyk MMC" is the off-gases produced when molybdenum concentrates are roasted, where rhenium is mostly found as Re2O7. High selectivity and overall efficiency are ensured by optimizing the process parameters at each of the multiple subsequent technical phases involved in rhenium recovery. Perrhenate sorption is less efficient when organic molecules and Mn(2+)and Cu2+ ions are present in the process fluids. Oxidative-precipitation techniques were used for the first purification: Mn ions were oxidized and precipitated using potassium permanganate, and Cu2+ ions were selectively precipitated using an ammonium sulfide solution (NH4)(2)S. ICP-OES was used to assess the composition of the solutions, while SEM and EDS were used to examine the roasting gas-dust products. Using contemporary analytical methods, a thorough investigation of the relevant phases of selective purification was conducted for the first time at JSC "Almalyk MMC." It was shown that treating the solutions with KMnO4 and (NH4)2S efficiently eliminates interfering elements without causing rhenium or molybdenum losses, thereby creating ideal conditions for the sorption of perrhenate ions later on. Manganese and copper concentrations dropped from 1.44 to 0.0039 and 2.68 to 0.0036 g/l, respectively, demonstrating the great purification process efficiency. Rhenium and molybdenum concentrations did not alter during these phases, suggesting that they were fully preserved.
This papershows the findings of a detailed investigation of the natural halite from the Bakhyt-Tany deposit. The mineral's composition is sodium chloride with the addition of calcium sulfate, magnesium salts, and some other matters, including a residue of less than 2% insoluble residue. Elemental assaying indicates the occurrence of elements like Ca, Mg, Al, Si, Fe, and Pb, which points to the occurrence of clay and some sulfate impurities. To understand how impurities are distributed in different sizes, a sample was classified using a sieve with a mesh of 0.2 mm. It was discovered that less than twenty per cent of the salt mass is a fine fraction (d < 0.2 mm), where up to 3.4% of insoluble impurities are found, and in the coarse fraction (d > 0.2 mm), this value is less than 1.8%. A mathematical model developed showed that the fine fraction and the total amount of the residue insoluble are directly related, which supports its use for estimating contamination and evaluating the effectiveness of the processes of desalination. Moreover, the generated 3D model revealed that temperature and humidity, in addition to raising the concentration of insoluble impurities, also increase the concentration of such impurities in the fine fraction even more. The results obtained also support the need for the pre-purification of halite before its use in food and other technological applications, and support the statement of the fractionation and desalination based purification process for halite.
In this study, using mathematical modeling, the change in Al2O3 content as a function of acid concentration during hydrochloric acid activation of alkaline-earth bentonite from the Navbahor deposit is investigated. During the experiment, the HCl concentration varied from 5% to 20%, and the change in Al2O3 content was nonlinear. To describe the experimental data obtained during hydrochloric acid activation of alkaline-earth bentonite from the Navbahor deposit, an exponential decay model was proposed, and its parameters were estimated by regression analysis. The accuracy of this approach is supported by the coefficient of determination (R2 = 0.964) and the root mean square error (RMSE = 0.231%), indicating high accuracy and stability. The results obtained show that the decrease in Al2O3 content under acid activation conditions exhibits a nonlinear dependence on hydrochloric acid concentration rather than on time, and they enable formulation of a mathematical expression for the quantitative description of the process and for evaluating the effect of concentration.
The study presents an investigation of the consequences of explosive impacts during blasting operations at the Zhairem deposit using numerical modeling in the Ansys LS-DYNA software package. Based on literature data and the physico-mechanical properties of rock materials, two modeling scenarios were implemented: the explosion of a single blast hole and a group of blast holes. Dependencies of internal and kinetic energies, displacements, velocities, and accelerations of the rock mass, as well as the distribution of stresses and pressures within the rock, were obtained. It was shown that the maximum equivalent stress during the explosion of a single hole reaches 923.73 MPa, corresponding to the zone of intensive rock mass destruction. For a group of blast holes, energy release increases by several orders of magnitude, reaching 1.2 & times;109 J. Characteristic phases of energy transformation and blast wave dynamics were identified, allowing the assessment of hazardous zones and potential consequences of unauthorized explosions. The results of the study can be used to improve the safety of blasting operations and to predict the impact of air-blast overpressure on buildings and structures.
The article presents the results of geopolymer technology development and a study of the performance of lightweight concrete based on a porous aggregate. The purpose of the study is to identify the transformations in composition and structure during the formation and operational testing of porous geopolymer concrete. The porous aggregate and binder are synthesized from molding mixtures of related composition containing sodium liquid glass and finely dispersed from thermal power plants' waste (fly ash and aluminosilicate microsphere). A thermal curing mode for concrete is proposed to ensure the formation of a porous structure with satisfactory resistance to mechanical stress and water. Phase transformations are studied during thermal synthesis of geopolymer material, with prolonged exposure of concrete to water and solutions of magnesium sulfate and sodium. Preliminary economic calculations are performed, indicating the advantages of porous geopolymer concrete compared to cement concrete based on expanded clay. The porous concrete based on geopolymer binder is intended for the production of energy-efficient wall products.
Humus-containing organic and organo-mineral fertilizers play a key role in increasing soil fertility due to their high water-holding capacity, improved water permeability, and ability to reduce phosphorus fixation by calcium and magnesium ions in calcareous soils and by sesquioxides in acidic soils. Organic matter from livestock waste, peat, and brown coal can enrich fertilizers with humus. However, plant residues such as aspen bark, agricultural husks, and licorice root meal are among the most effective additives to produce organic fertilizers. The present study evaluates the synthesis of phosphorus-humus fertilizers in grain form using indicator phosphate rocks discovered in the Kyzylkum deposit, Turkmenistan, and oxidized licorice paste, treated with hydrogen peroxide and acetic acid. The methodology lab experiment consisted of three steps. In the first step, the oxidation behavior of finely ground licorice meal (particle size < 0.1 mm) was investigated using an aqueous hydrogen peroxide solution and acetic acid at mass ratios relative to the organic fraction of the licorice meal in the range of H(2)O2: CH3COOH = 100 : (10-20) : (0.1-1). In the second step, the phosphate rock was decomposed by 92% sulfuric acid, requiring 30-80% equivalent amounts for monocalcium phosphate. In the third step, the resulting products were mixed with the oxidized licorice paste at a ratio of 100:10:1. This paper evaluates the optimal conditions for processing the phosphorus-humus fertilizer, also producing flowcharts for processing, such as phosphate, provided by each resource. The efficiency of this new technology is presented. The results suggest that low rock phosphate and waste licorice root are environmentally friendly and can be recommended as an alternate tool to reduce the use of high-consumption chemical fertilizers or time consuming conventional composting process.
In the field of mechanical engineering, one of the key tasks is quality control of manufactured products. Particular attention should be paid to quality control of small parts used in precision devices, metalworking machines, and equipment for the metallurgical and defense industries that operate at high rotational speeds. The aim of this study is to develop a device for controlling the out-of-roundness and eccentricity of rollers weighing up to 10 g. The paper proposes a device using a new method of free rotation of cylindrical products with a radius of r = 4 mm on support rollers rotating at a speed of up to 15000 rpm. The advantage of this work is that the geometric and kinematic parameters of the device were determined depending on the mass-geometric characteristics of the controlled products in the absence of radial displacement of the center of mass: e=0. Five products with a conditional displacement of the center of mass e=4; 6; 8; 12; 15 mu m, artificially created by removing a certain amount of material from the average outer surface. The mass of the product before and after removal was determined on analytical scales. The number of measurements of one product at each roller rotation speed was n=12. Based on the data obtained, the average angle of product breakage from the rollers was calculated, which can be used to judge the quality of the controlled products: as the eccentricity increases, the angle at which the product breaks from the rollers decreases. The measurement accuracy of the device was evaluated for the case when measurements were taken for a product with e=8 mu m at nr=9000 rpm.
Below is a scientific article explaining the results of a comprehensive study on the desorption of fluoride from mineralized waste (MM) of the Central Kyzylkum phosphate deposits in an acidic environment, studied by experiments and mathematical modeling. The interaction between fluorapatite present in MM and acidic wastewater (AWW) was studied in detail. Acidic components in AWW, mainly free fatty acids, promote the decomposition of fluoride in MM through ion exchange mechanisms. Experiments were performed at 333 K with 30 minutes of mixing for different AWW: MM mass ratios from 100:10 to 100:40. The initial pH of the MM samples was close to neutral, while the pH of the AWW was 2.2; therefore, the pH in the mixtures was acidic. Values of q(e) (fluoride adsorbed per unit mass) and C-e (equilibrium fluoride concentration) were calculated for each mixture. Using these data, a regression graph was plotted according to the Langmuir adsorption model. A linear equation obtained from the graph gave qmax = 7.48 mg/g and K-L= 0.027 L/mg. An R-2 value of 0.93484 obtained from the Langmuir equation showed that the model and experimental results are in good correlation. Fluoride ions in AWW can be converted into HF gas by strong acids and released into the atmosphere. The identification of reaction products allowed them to propose a mechanism of decomposition. Two different streams of industrial wastes, MM and AWW, were combined in the current work, and this combination allowed the development of new technological solutions.
This work presents the synthesis of carbon nanofilaments obtained through the decomposition of graphite in methane plasma with argon admixture. The resulting nanostructures exhibit an amorphous configuration and remain transparent across the visible spectrum, making them attractive candidates for optical and optoelectronic applications. Atomic force microscopy revealed that the filaments form a compact, vertically oriented network on the substrate surface, while Raman spectroscopy provided information on their local bonding environment. Morphologically, the carbon filaments display flattened, ribbon-like forms, and their densely packed columnar structures reach an average length of similar to 36 nm. The optical transmission spectrum showed transmittance of similar to 65% near 400 nm, similar to 75% within the visible region, and nearly 80% in the near-infrared range, gradually increasing toward longer wavelengths. This degree of transparency in the visible spectrum is sufficient for practical device applications. When the incident light wavelength is comparable to or smaller than the inter-filament spacing (100-500 nm), light propagation occurs through reflections from the filament walls. The optical band gap of the structures was determined to be similar to 2.85 eV. Overall, the analysis of structural and optical properties confirms the successful fabrication of amorphous carbon nanofilaments, highlighting their strong potential for integration into advanced optoelectronic systems.
Semen Padang is a company engaged in the mining of limestone and silica rock as the main raw materials for cement production. The mining system used is open-pit mining. This study discusses the effect of geometry on rock fragmentation. The purpose of this study is to determine the blasting geometry and identify the causes of limestone block formation at the PT. Semen Padang site. The research focuses on fragmentation because fragmentation is a determining factor in the success of blasting activities. Fragmentation plays an important role in improving the company's targets, and the distribution of fragmentation must be optimal. To control fragmentation, blasting geometry is required as a parameter. Based on the results of the researcher's observations in the field, the size of rock chunks in the company that are larger than 80 cm is around 25%, so it is necessary to re-evaluate the blasting geometry. The purpose of this study is to determine the geometric design that produces the desired fragmentation, which is below 15% on an 80 cm sieve, so that production can be increased and a comparison can be made between the R.L Ash, C.J Konya, and ICI Explosive methods. The method used for the ideal blasting geometry design is the R.L Ash method with supporting theory using the Kuz-Ram theory. After data processing, the ideal geometry was obtained with a load value of 4.32 m, a distance of 5.18 m, stemming of 4.32 m, a blasting hole depth of 12.1 m, a filling column length of 7.78 m, and a blasting hole diameter of 5 inches, with a lump fragmentation percentage of around 15%.
High-purity NaCl is required for chemical processes. Halite from the South Kazakhstan Bakhyt Tany deposit contains CaSO4 and Ca-2(+)/Mg-2(+) that degrade quality and operability. The article presents statistical processing and modeling of impurity deposition with phosphate ions using an automated calculation process. A stoichiometric amount of Na3PO4 was added to the NaCl 315 mol/dm3brine, stirred for 25-30 minutes, precipitated for 30 minutes,and filtered.Sulfate was quantified by barium-sulfate turbidimetry; residual Ca-2(+)/Mg-2(+) in the filtrate wasmeasured titrimetrically. The Excel 2000workbook performs coefficient estimation, significance testing, model adequacy testing, and error analysis. Response optimisation is also carried out through protected input fields. The resulting second-order models are adequate within the studied range of factors, reflect significant main effects and interactions, and predict optimal process modes, which have been confirmedexperimentally. Under optimized conditions, removal reached 99.9% for Ca(2)(+)and 99.8% for Mg-2(+). Sulfate ions remained at trace levels in the NaCl product. The framework enables reproducible parameter selection and provides a basis for integrating near-zero-waste handling of co-products in subsequent process design.
In this study, the acid activation process of the bentonite clay, which was conducted for producing a bleaching sorbent for the oil and fat industry, was mathematically analyzed. Increase in SiO2 content under different concentrations of HCl was analyzed using the different mathematical models. During acid activation, increasing the acid concentration from 5% to 20% resulted in an increase in the SiO2 content from 61.94% to 65.12%. During the activation process, a moderate increase in HCl concentration caused the improvement of the sorption properties of the clay by dissolving some components and restructuring the active sites. An excessive increase in the concentration of HCl leads to degradation of the mineral structure and partial breakdown of the silica framework, which negatively influences sorption performance. Analysis of the obtained results using the different mathematical approaches showed that an increase in SiO2 content during activation corresponds fully to a linear model. According to this, a linear model was described by the equation y = 60.785 + 0.2088X. Accuracy of the results obtained from the linear equation was confirmed by a coefficient of determination, R2 = 0.9845, indicating a high accordance with the experimental data. This model mathematically predicts the increase in SiO2 content and proves that the activation process proceeds as a linear function. A mathematical approach to the activation process enables one to calculate in advance the properties of sorption of the clay, to reduce the consumption of acid and water, and to calculate the eventual demands of other reagents.
