Vol 281 Iss. 2

Against the background of ongoing reform of preferential regimes in the Arctic Zone of the Russian Federation (AZRF) and the Far Eastern Federal District (FEFD), there is a growing need for institutional solutions that can simultaneously reduce the environmental risks associated with technogenic deposits (anthropogenic mineral accumulations, including secondary mineral resources contained in mine tailings) and maintain the investment attractiveness of projects for their development. The aim of this study is to develop a universal approach to regulating projects for processing technogenic deposits in the AZRF and FEFD macroregions that balances the standardization and differentiation of support measures while accounting for regional differences in the structure of the technogenic legacy and risk profiles. The theoretical framework combines the institutional approach, the concept of government and market failures in environmental regulation, the theory of complementary macroregional development, and the concept of economic incentive instruments. The methodological toolkit includes content analysis and comparison of the regulatory framework governing preferential regimes in the AZRF and FEFD, comparative analysis of the regional distribution of technogenic deposits and the regimes operating in those regions, synthesis of the findings and development of a model for harmonizing the regimes as applied to technogenic deposit development projects, testing of the model using hypothetical examples, and verification by comparison with existing instruments for stimulating the processing of technogenic resources and with the results of previous studies. The study uses statistical data from Rosstat and Rosnedra, as well as information from open scientific and government sources aggregated for the AZRF and FEFD regions. A two-component assessment system is proposed, based on the intersection of an index of project economic feasibility and an integral index of the priority of involving technogenic deposits in order to reduce environmental risk. The resulting matrix makes it possible to rank projects by implementation priority and by the level of government support required. The scientific novelty lies in integrating the structure of the technogenic legacy, environmental risks, and preferential-policy parameters within a single risk-oriented analytical framework; the practical significance lies in the possibility of using this framework to configure a unified preferential regime for the AZRF and FEFD.

An assessment is presented regarding the use of iron-magnesium production waste for the remediation of cadmium-contaminated soils. The waste contains, mg/kg: Mg 175,000, Fe 52,000, K 30,000, and traces of Cu, Zn, and Co, with no detectable Cd. Garden cress (Lepidium sativum L.) was grown for seven days on a substrate containing 10 mg/l Cd and treated with three doses of an iron-magnesium composite (IMC): 10, 60, and 120 g/m². FeSO₄, MgSO₄, and a combination thereof were used for comparison. Parameters evaluated included germination rate, root length, pH, redox potential, mineralization, moisture content, and metal concentrations in soil and plants (via atomic absorption spectrophotometry); root barrier coefficients (RBC) and translocation factor (TF) were calculated. The high IMC dose (T4, 120 g/m²) maximized Cd immobilization (reducing the mobile fraction by 38 % to 9.6 mg/kg), eliminated Mg deficiency, and stimulated root growth by 30.6 %, but caused soil salinization (TDS up to 740 mg/l) and the accumulation of Ni (up to 39.8 mg/kg) and Co (up to 5.2 mg/kg) in the soil. The low dose (T6, 10 g/m²) reduced Cd availability to 11 mg/kg and increased root growth by 10.4 % without significant salinization (TDS 270 mg/l). Ni and Co were effectively retained by the roots (RBC 1.96 for Ni, >3.0 for Co), and their transport to the shoots was minimal (TF 1.26 for Ni, 0.60 for Co). For short-term application, a dosage of 120 g/m² is justified, provided salinity is monitored. The optimal long-term solution is a dosageof 10 g/m².

The paper presents a scientific approach to developing and evaluating the efficiency of composite sorbents for remediation of oil‑contaminated soils along the Arctic coastlines. The authors use a chitin‑chitosan complex derived from crab processing waste as the sorption base. Activated sludge – a by-product of wastewater treatment facilities in the Murmansk Region – serves as a source of oil‑oxidizing microorganisms adapted to northern conditions. The study reports results of initial material characterization, including comparative spectral analysis of the chitin‑chitosan complex, analytical control of heavy metal content in the activated sludge, and its microbiological assessment. The composite sorbent formulation is developed via mathematical modelling using orthogonal central composite design. The va-riable factors are the component contents in the sorbent; the response function is the residual petroleum content in soil after remediation. Researchers run the experiments at 10±2 °C, matching the average daily temperature along the Kola Peninsula coastlines during summer. The resulting mathematical models describe how sorbent efficiency, assessed by residual petroleum content in soil, depends on component ratios; these models guide the selection of the optimal formulation. 3D models of oil pollution degradation are built to visualize and compare the performance of sorbents with different formulations. The correctness of the optimal sorbent formulation, selected based on the mathematical models, is additionally verified through phytotoxicity test. The paper also demonstrates the high remediation efficiency of the developed sorbent for oil‑contaminated soils compared to the commercial analogue. The study finds that the residual petroleum content stays 2-4 times lower with the composite sorbent throughout the entire research period. Based on the research conducted, the authors propose engineering principles for producing the composite sorbent from organic wastes and for its application in effective treatment of oil-contaminated coastlines under Arctic conditions.

Today, processing low-grade raw materials draws widespread interest. This aligns with the federal project “Circular Economy”, which explores alternative raw material sources – overburden rocks and naturally occurring soils of similar composition – and practical processing technologies to replace traditional materials like crushed stone and sand. Based on the raw material characteristics, engineers develop soil-concrete formulations with a complex mineral binder to meet required physical-mechanical and water-physical properties. To study how the raw materials interact with binder components during composite synthesis, researchers apply a set of physicochemical analytical methods using high-precision equipment. They evaluate the raw material properties according to GOST 25100-2020 and test the synthesized composites per GOST R 70452-2022. Findings show that these procedures produce effective road-construction composites for road bases, achieving strength grades M40-M75 and frost resistance grades F10-F15. The proposed approaches support scaling the solution, including recycling mining waste – mainly clayey overburden rocks – into usable construction materials.

Given the growing societal demand for the development of enterprises that ensure minimal environmental impact, there is a need to develop waste-free technologies. The concept of realizing the potential of technogenic waste is an integral component of creating a circular economy. The aim of this study is to utilize technogenic waste in a safe, environmentally balanced, and economically efficient deposit mining technology within the framework of a circular economy. The necessity of transitioning from a conventional mining system to multi-stage extraction systems for the mining of potassium-magnesium (water-soluble) ores is substantiated. The possibility of completely replacing specially mined components of the backfill composite with technogenic waste, including potassium-magnesium ore beneficiation waste, granulated blast-furnace slag, and deactivated ZSM-5 zeolite, is confirmed. It is established that the use of ZSM-5 as an activator and fiberglass as an inhibitor makes it possible to form a backfill composite with improved strength characteristics. The optimal composition of the backfill material includes 60 % beneficiation tailings, 29.7 % granulated slag, 0.3 % fiberglass, and 10 % ZSM-5. It is demonstrated that the use of multi-stage extraction with backfilling of the mined-out space enhances the environmental and technological safety of mining potassium-magnesium (water-soluble) ores. It is established that technological safety is achieved by minimizing horizontal deformations of the undermined rock mass, thereby ensuring the preservation of the water-protective stratum and relieving inter-chamber pillars from increased stresses, which contributes to their greater stability over time. It is determined that environmental safety is achieved through the utilization of technogenic waste in the backfill composite, as well as through the reduction of horizontal deformations of the undermined rock mass, thereby minimizing disturbance of the ground surface.

Fly ash can be considered a promising secondary raw material for the production of high-strength porous mullite ceramics, since the absence of a need to grind the initial batch materials makes it possible to significantly reduce energy consumption. In this study, promising ceramic samples were produced using fly ash and aluminum ore, specifically low-iron bauxite, as an Al2O3-adjusting component. Thermogravimetric and X-ray diffraction phase analyses were used to determine the sequence and temperature ranges of phase transformations in the system “fly ash – bauxite” and to establish the optimal thermal treatment regime. Several exothermic peaks were observed in the 1200-1300 °C temperature range, reflecting a sequence of phase transformations. Mullite forms through a reaction between quartz and cristobalite, which pass into a transient liquid phase, and γ-Al2O3, formed by the decomposition of boehmite. The total mullite phase content reaches 83-84 %, which is significantly higher than the values reported by other researchers, including those who used various additives to accelerate mullite formation. Scanning electron microscopy was used to trace the evolution of the microstructure of the obtained samples as a function of synthesis temperature. As the treatment temperature increases to 1300 °C, sintering gradually intensifies, resulting in the formation of larger pores. Acicular mullite crystals form around flake-like γ-Al2O3 crystals, some of which subsequently transform into corundum. Laboratory tests of the finished ceramic samples confirmed that their technical characteristics – density, porosity, and compressive strength – meet the requirements for refractory, thermal insulation, and chemically resistant materials. The study presents the technological principles for developing high-strength and porous mullite-based ceramics intended for use in construction and thermal insulation applications.

This study focuses on developing a method for utilizing phosphogypsum, a large-tonnage waste product from phosphate raw material processing, whose disposal sites are sources of complex negative impacts on the environment. As a promising approach to the utilization of gypsum-containing waste, the study considers the interaction of phosphogypsum with a sodium carbonate solution (carbonate conversion), which yields calcium carbonate, a marketable product referred to as phosphochalk. Existing technologies typically produce a fine-grained material, which hinders filtration and restricts the potential applications of phosphochalk. This study aims to determine the carbonate conversion parameters that enable the production of phosphochalk with tailored particle size characteristics while maintaining a high degree of feedstock conversion. A series of single-factor experiments was carried out to evaluate the influence of reaction conditions – temperature, Na₂CO₃ concentration in the carbonate solution, liquid-to-solid (L:S) ratio, and phase contact time – on the conversion of CaSO₄·2H₂O. The results showed that raising the conversion temperature to 90-100 °C and increasing the L:S ratio to 10 promote intensive nucleation of CaCO₃ crystals and the formation of large agglomerates. A Na₂CO₃ concentration of 250 g/dm³ and a phase contact time of up to 3 h together yield phosphochalk with a particle size of D90 = 45 μm at a conversion degree of 98.8 %. In terms of its characteristics, the resulting product is suitable for use in the metallurgical industry as a raw material for flux production, which demonstrates its competitiveness in the secondary raw materials market. The recommendations developed in this work enable the design of a low-waste technology for processing technogenic raw materials, consistent with the principles of sustainable development and helping to reduce the environmental burden.

The disposal of drilling sludge is a pressing issue in the oil and gas industry. The present study investigates the effect of three sludge cleaning methods for the Urengoy oil and gas condensate field (washing with water, washing with gasoline, and calcination at 400 °C) on the physicochemical characteristics and mechanical properties of model proppant samples. The scientific novelty of the present study lies in the description of a direct quantitative correlation between the phase composition of the model samples and their ultimate compressive strength. This correlation had not previously been demonstrated for drilling sludge from the Achimov Formation. The initial sludge was characterized using a combination of methods, including X-ray phase analysis, Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and X-ray fluorescence analysis. It was shown that it contains 2.2 wt.% residual hydrocarbons and is a polymineral raw material. It has been established that washing with gasoline most effectively removes hydrocarbons (cleaning degree up to 97 %), while washing with water effectively removes chlorides (reduction to 0.05 %). Calcination at 400 °C does not ensure complete removal of hydrocarbons due to the coking of heavy fractions and leads to the amorphization of clay minerals. Using quantitative X-ray phase analysis of model proppant samples, a relationship between the mullite content and the ultimate compressive strength was established. The maximum strength (125.38 MPa) was achieved for the sample obtained from water-washed sludge, which is due to its high mullite content (23.5 wt.%) and minimal amount of amorphous phase. The lowest strength (74.79 MPa) was obtained for the model proppant sample made from calcined sludge, due to the destruction of clay minerals. The results of this work substantiate the choice of water washing as the optimal method for preparing drilling sludge for the synthesis of strong propping agents.

The accumulation of petroleum sludge in port facilities constitutes a significant environmental liability due to its high viscosity and complex management. This study evaluates the technical feasibility of using this waste as the main binder in the formulation of a cold asphalt concrete, combining it with endogenous aggregates (serpentinites from nickel industry rejects and vitric tuffs) for road maintenance in Moa, Cuba. A physical-chemical characterization of the materials was carried out, and asphalt mixtures with sludge contents of 8.0; 8.5, and 9.0 % were designed. Twenty-four specimens were fabricated using Marshall compaction, and their properties (density, stability, and deformation) were evaluated according to Cuban standards. After applying statistical quality control (rejection of specimens with > 10 % deviation), the experimental results demonstrated that curing time is a determining factor. After 45 days of curing at room temperature, the optimal mixture (8.5 % sludge) developed a Marshall stability of 7.32±0.21 kN and a deformation of 3.38±0.15 mm, satisfactorily complying with the quality indices of Cuban standard NC 54-18:1985 for dense mixtures. Environmental leaching tests confirmed the encapsulation of contaminants. This approach offers a sustainable technical solution for road infrastructure and contributes to the circular economy through the valorisation of industrial waste.

This study evaluates the effectiveness of bioremediation of oil-contaminated terrestrial ecosystems using a composition of organomineral ameliorants. The aim of the study is to establish the influence of ameliorants on reducing the phytotoxicity of oil-contaminated organogenic soils and to track the dynamics of the decline in oil concentration in the soil under their influence. The study is directed at developing an ecologically safe and sustainable method for cleaning soils from oil contamination, which minimizes the negative impact on the environment and contributes to the restoration of soil fertility. As a result, the optimal ratio of components of the peat-diatomite ameliorant (PDA) for activating bioremediation processes in oil-contaminated soils was experimentally substantiated. The following component ratio of PDA was recognized as the most effective for the bioremediation of oil-contaminated soils: peat 51.5-53.5 %; sapropel 31.0-33.5 %; diatomite 15.0-15.5 % (by mass of air-dry matter). A direct dependence of the efficiency of oil destruction in oil-contaminated ecosystems on the application of PDA in the recommended composition was established. The results of the research confirm the effectiveness of the developed PDA.

During mining and mineral processing, technogenically disturbed lands are generated and require reclamation. This paper considers the feasibility of producing an effective ameliorant for reclaiming disturbed lands at mining facilities using complex organomineral ameliorants derived from chemical industry waste containing cellulose nitrates. An approach to producing such complex organomineral ameliorants is substantiated. The resulting ameliorants are shown to meet the chemical-composition requirements of GOST R 54534-2011 for use in the technical and bio-logical stages of reclamation and to possess additional beneficial agrochemical properties. In a pot experiment with oat (Avena sativa) and meadow bluegrass (Poa pratensis), the application of complex organomineral ameliorants produced pronounced positive increases in above-ground plant biomass relative to background models with sand alone: 58.8-104.9 % for oat and 245.5-1721.8 % for meadow bluegrass. Compared with the background model using livestock waste (cattle manure), biomass increases were 5.2-11.6 % for oat and 290.9-413.8 % for meadow bluegrass. A positive effect on the root systems of both species was also observed. The proposed ameliorants based on the waste in question are shown to be suitable for reclamation of mining facilities, and the utilization technology offers a positive economic effect.

Flotation tailings of copper-nickel ores that contain Ca-, Mg- and Fe-silicates are of interest as a potential feedstock for the mineral carbonation of CO₂. The aim of this study was to assess the potential of the stored tailings of the Talnakh Concentrator (MMC Norilsk Nickel PJSC) for sequestering carbon dioxide as carbonate phases and to identify the factors that control the efficiency of this process. The study combined a suite of mineralogical and geochemical methods (scanning electron microscopy, X-ray diffraction, IR spectroscopy, ICP-MS, inorganic carbon determination), a laboratory CO₂-saturation experiment at 25 °C and 1 bar for 7 days, and thermodynamic equilibrium modeling by Gibbs free energy minimization (HCh software package). The tailings were found to contain, alongside abundant sulfides, primarily pyrrhotite Fe_nS_{n + 1}, pyroxenes including diopside CaMgSi₂O₆, plagioclases of the NaAlSi₃O₈–CaAl₂Si₂O₈ series, serpentine Mg₃Si₂O₅(OH)₄, and amphiboles, i.e. Ca-, Mg- and Fe-silicates capable of participating in carbonation reactions. In the experiment, the total carbonate phase increased by 1.92 wt.%, mainly as dolomite, without any additional activation of the material. In the model calculations, the CO₂ partial pressure had the strongest effect on carbonate yield, whereas raising the temperature within 25-100 °C reduced the carbonate content owing to the redistribution of Ca and Mg into silicate minerals. Secondary silicate formation is shown to compete with carbonate formation for divalent cations, limiting the actual potential of the process. The tailings can be regarded as a secondary mineral resource for CO₂ sequestration; however, practical implementation requires further assessment of kinetic constraints and the long-term stability of the newly formed mineral phases.