Journal of Chemical Technology and Metallurgy

A NEW METHOD FOR CONVERSION WASTE BIOMASS INTO USEFUL PRODUCTS WITH WIDE APPLICATION POSSIBILITIES

2026-01-28T13:43:49+00:00

This study investigates a thermochemical method for the conversion of industrial biomass residues - specifically peach shells, walnut shells, and cherry stones - into high-value commodities. By employing flash pyrolysis across a range of temperature gradients, a waste-free processing cycle was established, yielding solid, liquid, and gaseous products.
The research focuses on identifying the optimal process parameters and characterizing the physicochemical properties of the resulting fractions. Results indicate that the yield and molecular composition of the products are highly dependent on the precursor’s botanical origin and the specific pyrolysis temperature.

EFFECT OF ULTRASONIC TREATMENT AND CALCINATION TEMPERATURE OF RICE HUSK ASH ON THE CHARACTERISTICS OF SILICA-CHITOSAN COMPOSITES

2026-02-05T08:10:31+00:00

This study investigates the effect of calcination temperature and ultrasonic treatment during the extraction of silica from rice husk ash and its implications for the characteristics of silica-chitosan composites. Rice husk ash was calcined at temperatures of 500, 600, and 700°C, followed by extraction using 2M NaOH solution with and without ultrasonic treatment. The extracted silica was subsequently combined with chitosan to form silica-chitosan composites. Characterization was carried out using X-ray fluorescence (XRF) to determine SiO₂ purity, Fourier-transform infrared spectroscopy (FT-IR) for functional group identification, and X-ray diffraction (XRD) for structural analysis. The results showed that increasing the calcination temperature from 500°C to 700°C generally enhanced the silica yield (79.6 - 90.8 %) and purity (92.3 - 97.4 %). Ultrasonic treatment further improved the yield by approximately 2 - 5 % and increased the purity by about 0.5 - 2 % at each calcination temperature. FT-IR and XRD analyses indicated that the obtained silica was predominantly in the amorphous phase with strong Si-O-Si bonds, while the silica-chitosan composites exhibited intermolecular interactions involving -OH, -NH2, and Si-OH functional groups. The combination of calcination temperatures of 600 - 700°C and ultrasonic treatment produced high-quality silica that has strong potential to enhance the performance of silica-chitosan composites for dye adsorption and heavy metal ion removal applications.

DETERMINATION OF OPTIMAL CINNAMON POWDER LEVEL IN BISCUITS USING MULTIVARIATE ANALYSIS AND EXPERIMENTAL VALIDATION

2026-05-22T10:45:49+00:00

The incorporation of plant - based functional ingredients into bakery products represents a promising approach to enhance their nutritional and technological properties. In this study, the optimal level of cinnamon powder in butter biscuits was determined using a combined experimental and data - driven approach. Biscuits containing 0 - 6 % cinnamon powder were produced and evaluated in terms of physicochemical composition, color characteristics, texture, electrochemical parameters (pH, EC, TDS, ORP), and sensory attributes. A multivariate analysis framework was applied, including Z - score normalization, correlation - based feature selection, regression modeling, and linear programming, to identify the most informative variables and determine the optimal formulation. The results showed that cinnamon addition significantly affected moisture, dietary fiber content, color parameters (L*, a*, b*), and electrochemical properties, as well as sensory acceptance. The proposed model identified an optimal cinnamon powder level of 3.12 %, representing a balance between improved nutritional value and acceptable sensory and technological characteristics. At this level, biscuits exhibited enhanced functional properties, moderate color change (ΔE), and high overall acceptability. The study demonstrates the applicability of data - driven methods for formulation optimization in bakery products and provides a basis for the development of functional foods enriched with cinnamon.

STUDY OF THE SOLUBILITY OF THE CALCIUM CHLORATE - TRIETHANOLAMMONIUM MONOCHLOROACETATE - WATER SYSTEM

2026-03-05T12:42:04+00:00

The objective of this study was to investigate the physicochemical interactions between calcium chlorate and triethanolammonium monochloroacetate in aqueous systems and to determine their phase behaviour. The ternary system Ca(ClO₃)₂ - (C₂H₄OH)₃N·ClCH₂COOH - H₂O was studied using the visual-polythermal method combined with physicochemical analytical techniques. A polythermal solubility diagram of the system was constructed over the temperature range from -52°C to 47°C. The analysis revealed the crystallization fields of ice, Ca(ClO₃)₃ hydrates (Ca(ClO₃)₂·6H₂O, Ca(ClO₃)₂·4H₂O and Ca(ClO₃)₂·2H₂O), triethanolammonium monochloroacetate, and a newly formed crystalline compound with the composition ClCH₂COOH·Ca(ClO₃)₂·(C₂H₄OH)₃N. The formation and individuality of the new compound were confirmed by chemical analysis, IR spectroscopy and scanning electron microscopy. The obtained results provide a physicochemical basis for improving chlorate-based defoliant formulations and optimizing their production technologies.

LONG-TERM PLANT MICROBIAL FUEL CELL USING ELEOCHARIS PALUSTRIS

2026-04-10T07:06:02+00:00

Plant microbial fuel cells (PMFCs) have attracted increasing interest as alternative bio electrochemical systems due to their sustainability and environmental compatibility. This technology is based on the symbiosis between living plants and soil microorganisms. The rhizosphere-associated microbial community catalyses the degradation of plant root exudates, resulting in sustainable bioelectricity generation. The system performance is strongly influenced by several factors, including the plant species used and the sediment characteristics. Although many plant species have been tested in PMFCs, Eleocharis palustris has rarely been investigated for this application. This study evaluates the long-term performance of a PMFC utilizing Eleocharis palustris as a primary macrophyte, with sediment collected from Lake Mandrensko (Burgas, Bulgaria) serving as a microbial and electrochemical substrate. Sediment analysis showed elevated levels of organic matter and nutrients (COD - 3.6 g kg⁻¹, phosphate - 2.8 g kg⁻1, and manganese -
1.3 g kg⁻¹), supporting the metabolic activity of electrogenic bacteria and indicating the suitability of the sediment as a substrate for sustainable PMFC operation. The system was configured as a single-chamber bio-electrochemical reactor, featuring an anode embedded in the sediment and a cathode exposed to atmospheric oxygen. During the 80-day operational period, the system exhibited three distinct voltage phases: an initial adaptation phase (60 - 80 mV), a fluctuation phase (150 - 230 mV), and a final phase characterized by declining voltage and substrate depletion. A clear correlation between COD concentration and voltage output was observed, with the highest substrate level of 10.53 g COD dm⁻3 corresponding to a power density peak of 2339.34 mW m⁻³.

KINETIC MODELLING OF BORONIZING KINETICS OF THE SVERKER 3 STEEL WITH THE TAYLOR EXPANSION MODEL AND DIMENSIONAL ANALYSIS

2026-04-19T08:47:51+00:00

This study aims to model the boronizing kinetics of Sverker 3 steel in the temperature range 1173 - 1273 K for treatment times between 1 and 7 h. The first used approach is the Taylor expansion (TE) model. It considers the diffusion of boron atoms under transient regime through the surface of the treated Sverker 3 steel. Whereas the second one is the dimensional analysis (DA) model based on the Buckingham’s Pi - theorem. It enables the reduction of the number of variables involved in complex physical phenomena. In formulating this second model, dimensionless groups were derived to simulate the thicknesses of the FeB and Fe₂B layers. The predicted values were found to be in good agreement with the experimentally measured layers’ thicknesses. Furthermore, the boron activation energies determined for the FeB and Fe₂B layers were 214.92 kJ mol^-1 and 203.20 kJ mol^-1, respectively, using Taylor Expansion (TE) model and were finally compared with values reported in the literature.

INFLUENCE OF SOLUTION pH ON SLAKE DURABILITY AND CHEMICAL WEATHERING OF GRANITE: AN ASSESSMENT USING CIA AND PIA INDICES

2026-04-09T12:40:12+00:00

The durability of rock materials under environmental conditions is governed by a combination of mechanical disintegration and chemical weathering processes. This study investigates the influence of solution pH on the slake durability behaviour of granite collected from the Bundelkhand region of central India. Repeated wetting-drying cycles were performed following ISRM standards using slaking media with pH values of 3, 5, 7, 9, and 11. The chemical composition of the rock samples and molar proportions of key oxides were computed to evaluate chemical weathering trends. Two widely accepted geochemical indices - Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) - were used to quantify the degree of alteration during successive slaking cycles. The results indicate that CaO exhibits the highest mobility, particularly under acidic conditions, signifying preferential leaching of Ca bearing minerals, while Al₂O₃ remains relatively immobile and becomes residually enriched. CIA values ranging from approximately 72 to 90 indicate moderate to intense weathering, with increasing trends in later cycles reflecting progressive alteration. Consistently high PIA values ( > 85) highlight dominant plagioclase weathering and the transformation of feldspar minerals into clay-rich phases. Mildly acidic conditions (pH = 5) were found to promote sustained and systematic chemical weathering, whereas extreme pH environments accelerated reactions but resulted in higher variability.

STUDY OF THE CHARACTERISTICS OF MICROSILICA DUST GENERATED DURING FERROSILICON PRODUCTION

2026-03-25T06:59:45+00:00

Microsilica dust generated during ferrosilicon production accumulates in substantial quantities, creating significant environmental concerns. However, its compositional and structural features enable its consideration as a valuable secondary raw material. In this study, technogenic microsilica obtained from ferrosilicon production waste in Uzbekistan was comprehensively characterized for the first-time using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and transmission electron microscopy coupled with energy-dispersive spectroscopy (TEM/EDS). Its potential application as a functional filler was also evaluated. According to XRF analysis, silicon was identified as the dominant component, accounting for 50.6 wt. %. XRD results revealed a broad diffuse maximum within the 2θ range of 15-30°, indicating that the material predominantly exhibits an amorphous structure. FT-IR spectra demonstrated intense absorption bands characteristic of Si-O-Si bonds. TEM images showed that the particles possess a spherical morphology with sizes ranging from 50 to 200 nm and exhibit a pronounced tendency toward aggregation. EDS analysis confirmed that Si and O are the prevailing elements in the composition. The spherical morphology and nanoscale structure of the particles indicate that microsilica is formed in the vapor phase during ferrosilicon smelting and subsequently undergoes rapid condensation. The results demonstrate a clear relationship between the chemical composition of microsilica and its amorphous structural state, highlighting distinctive features of technogenic microsilica generated under the conditions of ferrosilicon production
in Uzbekistan compared to conventional silica fume samples.

INFLUENCE OF GRAPHENE OXIDE ON THE PROPERTIES OF POLYPROPYLENE NANOCOMPOSITES

2026-04-30T13:58:48+00:00

In this work, the influence of small concentrations of graphene oxide on the physicomechanical properties of nanocomposites based on polypropylene and polyester oil was studied. A nano dispersed filler was added to the polypropylene matrix in amounts of 0.01 %, 0.05 % and 0.1 %. A rotary mixer with adjustable speed was used to homogenize the mixtures. To determine the characteristics of the new nanocomposite, test specimens were manufactured in accordance with EN 527 - 2 using the injection molding method. From the studies conducted, it was found that the introduction of graphene oxide nanoparticles into the polyolefin matrix in amounts of 0.01 %, 0.05 % and 0.1 % did not significantly affect the temperature-phase transitions. The addition of 0.1 % filler increased the hydrophobicity
of polypropylene by 8 %, the tensile strength at break increased by 14 %. There is a tendency towards an increase in the fluidity of the composite materials, but in general it can be concluded that the filler in these quantities does not significantly change the rheology of the polymer material. The filler has an impact on the thermal conductivity properties of the compound, since the graphene particles serve as nuclei for crystal formation.

THE INFLUENCE OF STEEL SLAG AND NANOCLAY ADDITIVES ON THE MECHANICAL AND DURABILITY PERFORMANCE OF UNSATURATED POLYESTER GYPSUM BASED COMPOSITES

2026-03-07T06:53:43+00:00

The current investigation examines the development and characterization of gypsum-based hybrids incorporating industrial steel slag, organo-modified nanoclay (Nanofil-15), and an unsaturated polyester (UP) resin. The formulations were designed to compare a conventional water-resistant system with UP-bound system. The fabricated samples were evaluated in terms of specific impact strength (Si), flexural performance, water absorption, and direct flame resistance. Microstructural analysis by scanning electron microscopy (SEM) was correlated with porosity (Vv) to clarify the relationship between packing efficiency and interfacial voids. The UP-bound gypsum (UPG) composite exhibited a substantial increase in impact resistance compared to the water-bound system primarily due to coordination interaction between the UP-carbonyl groups and the surface Ca²⁺ and Al³⁺ cations, which strengthen the interface
between the amorphous slag and crystalline gypsum phases. Incorporation nanoclay and stearic acid-modified slag (LS) further improved mechanical performance by promoting crack-deflection and interfacial micro-lubrication. The UP resin drastically reduced water absorption (< 1.0 %) by forming a hydrophobic shield around the mineral. Furthermore, slag additions which is rich in Fe₂O₃ and Al₂O₃ reduced the mass loss rate (MLR) by acting as an inorganic heat sink. These findings highlight the synergistic potential of polymer-mediated coordination to convert waste material into a durable, high-strength construction material.

CANTILEVER BENDING AND COMPRESSION PERFORMANCE OF HYBRID COMPOSITE LOAD - BEARING ARMS FOR UNMANNED AERIAL VEHICLES

2026-05-30T06:19:20+00:00

Lightweight load - bearing arms for unmanned aerial vehicles require high bending capacity, sufficient stiffness and stable local compression response at minimum structural mass. This work evaluates ten hybrid composite arm prototypes combining aluminium tubes, aluminium flat bars, aluminium angles or wooden rods with foam core, flax reinforcement and internal ribs. Cantilever bending tests were carried out at 10.0 mm min^-1 and 22.0°C, while short composite tube specimens were additionally tested in compression at room temperature. The maximum bending moment ranged from 260 Nm to 587 Nm. The highest bending moment was obtained for the five - aluminium - flat
configuration with foam and flax reinforcement, whereas the highest bending stiffness, 63.5 N mm^-1, was obtained when the same reinforcement concept also included internal ribs. The compressive strength of the S1 - S10 tube specimens ranged from 14.7 kN to 27.5 kN. The results show that flax/foam hybridisation strongly improves bending load capacity, while ribs mainly improve stiffness and shape stability but must be designed to avoid local stress concentration. The data provide an experimental basis for selecting practical reinforced hybrid composite arms for small UAV airframes.

DEVELOPMENT OF SPARK PLASMA SINTERED ALUMINIUM-NICKEL-COPPER (I) OXIDE METAL MATRIX COMPOSITE

2026-02-07T11:31:08+00:00

Effects of varied contents of copper (I) oxide (Cu₂O) and heat treatment on the phases and properties of spark plasma sintered Al-Ni-Cu₂O metal matrix composite was studied. The raw materials used were aluminium (Al) powder, nickel (Ni) powder and copper (I) oxide Cu₂O powder. Samples were made by blending pre-calculated amounts of raw materials in tubular mixer at a speed of 72 revolutions min^-1. The homogenous mixture was sintered at 550°C at a sintering pressure of 40 MPa, heating rate of 50°C min^-1 and holding time of 10 min in a graphite die of 20 mm. The phases in the sintered samples were characterized using X-ray diffractometry analysis (XRD). Addition of Cu₂O to the samples progressively improved on densification of the samples with increased Cu₂O contents. Hardness of the sintered samples was also investigated using Brinell hardness tester. It was observed that the phases which evolved in the sample were influenced by Cu₂O content. The presence of 12 % Cu₂O in sample C aided development of intermetallic phases within the sample. Presence of 16 % Cu₂O in the binary alloy led to development of more intermetallic phases in the sample. Additionally, the hardness and tensile strength notably improved, reaching approximately 107 HB for hardness and 369 MPa for tensile strength particularly with a 12 % copper addition after heat treatment at 260°C. It was concluded that the formation of intermetallic phases within the composite matrix is responsible for the improved hardness and tensile property of the samples.

EXAMPLES OF IMPLEMENTATION OF ENERGY-CONSERVATION APPROACHES IN OIL AND GAS PROCESSING

2026-03-16T05:17:22+00:00

The work is devoted to solving topical issues of energy and resource conservation (ERC) and increasing energy efficiency for hydrocarbon processing enterprises, considering the high energy intensity of industry process facilities, which is due to both objective reasons and irrational use of fuel and energy resources and direct heat losses. The goals and objectives of this work are to generalize and classify ERC approaches, proposals, methodologies and methods as applied to the hydrocarbon processing industry with an analysis of cases of their implementation, considering the “bottlenecks” of typical process facilities in the industry. The paper analyses the proposed areas and approaches to solving ERC problems in oil and gas processing, in particular, the implementation of a systemic
approach, decomposition principles, thermal integration methods, including between different-level objects, the use of pinch analysis to assess the potential for heat recovery and optimize heat exchange systems, the use of digitalization methods and computer modeling technologies, etc. As an example of energy and resource conservation, a rectification unit of a gas fractionation unit with a heat pump in its composition instead of the traditional approach to creating a temperature regime in the column is considered. It has been shown that this will reduce energy costs due to heat loss to the atmosphere, the use of its own flow as a coolant with savings in water vapor resources and the cost of cooling the product in air coolers. Together, this will lead to a more rational use of the process facility’s own resources.

ASSESSMENT OF PROSPECTS FOR IMPROVING BLAST FURNACE TECHNOLOGY FOR CO2 EMISSIONS

2026-01-24T10:18:40+00:00

The blast furnace route remains the dominant technology for primary ironmaking; therefore, improving its environmental performance is a key challenge for the steel industry. This study presents a comprehensive assessment of technological measures aimed at reducing carbon dioxide emissions from blast furnace operation using an original total energy and exergy balance model developed at the Iron and Steel Institute of the National Academy of Sciences of Ukraine. The influence of pulverized coal injection, hydrogen, natural gas, coke oven gas, metallic additives, hot blast temperature, heat losses and gas utilization efficiency on furnace performance and carbon footprint was investigated over a wide range of operating conditions. Attention was paid to the combined effects of hydrogen-
containing fuels and pulverized coal, as well as to operational constraints associated with raceway adiabatic flame temperature, oxygen enrichment requirements, top-gas temperature and the degree of direct reduction. The calculations demonstrate that different decarbonization measures provide significantly different environmental and economic effects. Among the investigated options, hydrogen injection and metallic burden additives exhibit the highest potential for reducing specific CO2 emissions, while improvements in gas utilization and thermal efficiency provide additional opportunities for lowering fuel consumption. The obtained results establish practical operating ranges for implementing low-carbon blast furnace technologies and may serve as a basis for evaluating decarbonization strategies in existing ironmaking plants.

GERMANY’S INDUSTRIAL TRANSFORMATION: ADVANCING THE CIRCULAR ECONOMY

2026-05-26T13:43:35+00:00

The industrial circular economy has become a key strategy for achieving sustainable development by reducing waste, extending product life cycles and improving resource efficiency. Germany is recognized as one of the leading countries in implementing circular economy principles through advanced recycling systems, industrial innovation and environmental legislation. However, the practice of planned obsolescence remains a significant examines the relationship between the circular economy and planned obsolescence in Germany. It analyses German industrial policies, examples of product durability issues and growing “right to repair” movement. This study highlights both the achievements and limitations of Germany’s sustainability transition. The findings demonstrate that although
considerable progress has been made in waste management and industrial recycling in Germany, stronger regulations and repair-oriented product designs are necessary to fully support a circular economic model.

BEHAVIOUR OF THE AlCoCr0.5NiY0.1 MULTI-PRINCIPAL ELEMENT ALLOY AT 1100°C

2025-11-07T13:29:33+00:00

The microstructure and phase composition of cast AlCoCr0.5NiY0.1 multi-principal element alloy (MPEA) have been determined. High-temperature oxidation of the alloy under study was carried out at 1100°C for 100 h in an atmospheric atmosphere. The high resistance of this MPEA to high-temperature gas corrosion is shown, the parabolic oxidation rate constant was k_p = 9.48 × 10^-13 g² cm^-4 s^-1. It has been established that the introduction of yttrium is an effective way to increase the heat resistance of multi-principal element alloys.

COMPUTER SIMULATION OF THE COMBINED ROLLING-EXTRUSION PROCESS FOR OBTAINING RODS FROM ALUMINIUM ALLOY 7075

2026-01-27T08:39:56+00:00

This article presents the results of numerical modelling of the combined rolling-extrusion process for producing rods of various diameters from alloy 7075. A 7075 ingot with a cross section of 14×14 mm and a length of 200 mm was used as the initial billet. The processing temperature was 450°C, and the diameters of the resulting rods were 5 and 9 mm. The geometric parameters of the tool, as well as the choice of roll rotation speed (4 and 8 rpm), are analysed. An analysis of the temperature conditions of the process, deformation conditions, and trajectory-velocity conditions is performed. It was found that with an increase in the drawing ratio from 4.0 to 12.9, the temperature of the rod at the exit from the die increases by an average of 80 - 100°C. Also, with an increase in the roll rotation speed in the deformation zone, the temperature increases by an average of 60°C. The maximum flow rate for a drawing ratio of 4 was 125 mm s^-1, while for a drawing ratio of 12.9, the maximum flow rate was 399 mm s^-1. When using rolls with different rolling diameters and low drawing ratios, incomplete filling of the groove will occur. At drawing ratios greater than 10, the groove is filled.

STUDY OF WEAR RESISTANCE OF METAL ALLOY 100Cr6 AS A RESULT OF VARIOUS HEAT TREATMENT MODES

2026-04-09T12:59:36+00:00

This study investigates the abrasive wear resistance of 100Cr6 (AISI 52100) bearing steel under three distinct heat treatment conditions: spheroidising annealing (as-delivered), normalising at 880°C, and oil quenching from 840°C followed by low-temperature tempering at 160°C. Cylindrical specimens were subjected to abrasive wear testing using a silicon carbide disc (P80 grit) under a constant load of 450 g over test durations of 25 and 60 min. Wear resistance was evaluated by the mass loss method, and microstructural characterisation was performed by optical metallography at 800x magnification. The results demonstrate that the as-delivered condition, characterised by a ferritic matrix with globular carbides and a hardness of 10 HRC, exhibits the highest mass loss and lowest wear resistance (E = 7417 m g^-1). Normalising produces a ferrite-pearlite matrix with a hardness of 18 HRC and improves wear resistance approximately four-fold (E = 29499 m g^-1). The quenched and tempered condition yields a tempered martensite matrix with finely dispersed carbides (< 0.5 μm) and a hardness of 61, 63 HRC, achieving the highest wear resistance (E = 67568 m g^-1) - approximately nine times greater than the as-delivered state. The findings confirm that optimised heat treatment is decisive in maximising the tribological performance of 100Cr6 steel for bearing applications.