Kompleksnoe Ispolzovanie Mineralnogo Syra = Complex use of mineral resources

Analysis of fragmentation results from limestone blasting activities at Semen Padang company

Fri, 27 Feb 2026 00:00:00 +0000

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%.

Thermodynamics of Evaporation of Liquid Magnesium - Tin Alloys

Wed, 28 Jan 2026 00:00:00 +0000

Based on the values of the partial pressures of magnesium above dimagnesium stannide and melts with tin, determined by the boiling point method (isobaric and isothermal variants, respectively) and tin, calculated by numerical integration of the Gibbs - Duhem equation in accordance with known expressions, the thermodynamic functions were determined: changes in entropy, enthalpy, and free energy of evaporation. Methods to determine the vapor pressure of isobaric and isothermal variants of the boiling point method and calculate thermodynamic values are described. The dependences of the values of partial vapor pressure of magnesium and tin were determined, based on which the energy functions were determined. The measurement error was 7.07%. Data on the change in evaporation entropies are presented graphically. An increase in the partial entropies of evaporation of magnesium and tin was noted with a decrease in their content in the alloy (each) to less than 20 at. %. Extremes are noted: a maximum for magnesium and a minimum for tin at a concentration corresponding to the stoichiometric composition of dimagnesium stannide (60 at. % Мg). The latter indicates the presence of a dissociating compound in the liquid phase that affects evaporation. The values of the change in enthalpy and Gibbs free energy of evaporation are tabulated. It was established that the values of partial and integral enthalpies and Gibbs free energy of vaporization monotonically increase from Mg to Sn in accordance with second-degree dependencies on the concentration of components in the alloy and linearly (Gibbs energy) with temperature. The very small change in the integral value of the free energy of evaporation of magnesium (0.03 ± 0.002 kJ/mol) at 1373 K (1100 °C) indicates a practical coincidence with the boiling point of magnesium. The energy functions of evaporation of magnesium-tin melts will supplement the thermodynamic database and can be used for thermal engineering calculations in the design of distillation processes and apparatus.

Deposition Methods of Multilayer Hard Coatings for Improving Tribological Performance: A Mini-Review

Thu, 29 Jan 2026 00:00:00 +0000

Multilayer hard coatings remain among the most effective engineering solutions for reducing friction and wear and for extending the service life of components operating under high contact loads. However, their practical performance is governed not by multilayering per se, but by the extent to which the selected deposition technology enables reproducible control over three key parameters: layer density and defectiveness, adhesion to the substrate and/or interlayers, and architectural tunability through interface quality. This mini-review systematizes deposition approaches relevant to tribological applications and proposes a generalized classification comprising chemical processes (sol–gel, chemical vapor deposition (CVD), atomic layer deposition (ALD), hydrothermal synthesis, electrodeposition, anodization, and electroless coatings), physical vacuum techniques of the PVD family (magnetron sputtering, cathodic arc deposition, hollow cathode discharge (HCD) ion plating, ion beam assisted deposition (IBAD), among others), as well as hybrid and functional solutions (PVD+CVD, composite, self-lubricating, and nanocomposite systems). It is demonstrated that the selection of a deposition process for multilayer architectures must be based on technological constraints that directly affect interface stability and coating durability, including the deposition temperature window and conformality, interfacial diffusion-induced boundary blurring, residual stresses, and critical defects such as porosity, macroparticles, and growth-related imperfections. Practical guidelines are formulated for correlating “architecture–deposition regime–microstructure–tribological behavior,” and key directions for future research are identified, including interface and defect engineering, targeted hybridization of deposition processes to compensate for intrinsic limitations (conformality, density, adhesion, and interface stability), and the use of predictive modeling validated by comparable tribological testing.

Investigation of synthesized carbon nanofilaments by reactive magnetron reactive sputtering methane decomposition

Mon, 23 Feb 2026 00:00:00 +0000

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 ~36 nm. The optical transmission spectrum showed transmittance of ~65% near 400 nm, ~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 ~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.

Device for automatic control of non-roundness and eccentricity of small rotating parts

A.K. Atalykova, Ye.O. Yeleukulov, A.P. Muslimov — Thu, 26 Feb 2026 00:00:00 +0000

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 μm, 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 μm at n_r=9000 rpm.