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Pashkevich Mariya A., Bykova Marina V. Methodology for Thermal Desorption Treatment of Local Soil Pollution by Oil Products at the Facilities of the Mineral Resource Industry. Journal of Mining Institute. 2022. DOI: 10.31897/PMI.2022.6
Gorlanov E.S., Leontev L.I. Directions in the technological development of aluminium pots // Journal of Mining Institute. 2023. EDN PYSEVM
Пашкевич М.А., Быкова М.В. Методология термодесорбционной очистки локальных загрязнений почв от нефтепродуктов на объектах минерально-сырьевого комплекса. Записки Горного института. 2022. DOI: 10.31897/PMI.2022.6
The use of stage-wise schemes in the development of deep quarries is one of the ways to increase the economic efficiency of mining a deposit and determining the optimal stage parameters remains an urgent task. Such parameters are stage depth, bench height, block length, etc. However, there is a wide range of values for these parameters. Therefore, to select the optimal values and evaluate the effectiveness of design solutions, it is advisable to use the net present value, which is an international notion. As a result of the analysis of data on deposits, a large number of variable indicators can be identified that presumably affect the efficiency of mining. The article proposes to divide all parameters of the quarry mining into two types: mine engineering and economic. The importance of each of them is determined by the measure of influence on the net present value. Thus, to assess the measure of influence of mining indicators, the average values of each of them are taken, and as a result of the alternating change of one parameter under study, the measure of its influence on the discounted income received is estimated. The results of the analysis of relevant factors, their evaluation and comparative analysis are important indicators that significantly affect the design decisions made and the effectiveness of the investment project.
The climatic factor of warming, which is evidenced by a significant number of scientists and research teams in Russia and the world, has a significant impact on the cryogenic state of permafrost soil, the preservation of which is one of the most common principles of construction in the North. The influence of projected climatic changes in planning up to 2050 on the efficiency of seasonal cooling devices, the principle of operation of which is based on seasonal soil freezing, is considered. The conducted modeling has shown that in a situation of stable climate, the preservation of the cryogenic state of permafrost soil is realized without the use of additional measures. With warming with a trend of 0.1 °C per year, seasonal cooling devices do not ensure the preservation of the current level of the cryogenic state of the soil and additional measures are required to increase their efficiency in the summer. In the case of more extreme warming with a rate of 0.25 °C per year, the modeling results show that seasonal cooling devices do not significantly affect the rate of soil thawing and the solution to the problem should be its complete replacement with systems with year-round action.
The peculiarity of the geological structure of carbonate reservoirs is their complex permeability and porosity characteristics, reflecting the simultaneous presence of cavities variety (fractures, caverns, pores). Loss of circulation during penetration of fractured rock intervals significantly increases well construction time due to lack of efficient plugging isolation compositions. The main disadvantages of traditional compositions are high sensitivity to dilution in the process of their injection into the absorption zone, as well as insufficient structural strength to prevent the isolation composition from spreading during the induction period. For efficient isolation of catastrophic absorption zones in conditions of high opening of absorption channels a new cross-linking plugging isolation composition has been developed, which allows to exclude disadvantages of traditional isolation compositions. Application of the composition will allow to reduce the injection volume of the isolation composition and the time of isolation works due to its resistance to dilution and movement of formation water in the absorption interval.
The study presents the results of the research on geodynamic and geological conditions of the Enisei site (Krasnoyarsk Krai), chosen for the construction of an underground research laboratory. The laboratory is being built at a depth of 500 m to assess the suitability of the rock mass for burying high-level radioactive waste. The rocks consist of weakly fractured gneisses, granites, and dikes of metadolerites. Field observations were conducted on bedrock outcrops. They included the determination of rock mass quality indicators, measurement of rock fracturing, and a rating classification of stability using N.Barton's method. GNSS observations were also made to monitor surface deformations. These data were used to develop a three-dimensional structural model, including lithology, fault disruptions, intrusive bodies, elastic-strength properties of rocks, and the sizes of zones influenced by faulting. It will serve as a basis for boundary conditions and the construction of three-dimensional variational models of stress-strain states, identifying zones of concentration of hazardous stresses, and planning in situ geomechanical experiments in underground mines of the laboratory. The obtained values of the modified QR index for the main types of rocks allowed their classification as stable and moderately stable, corresponding to strong and very strong rocks on Barton's scale and the massif rating according to geomechanical classification.
Coal is one of the world's most important energy substances. China is rich in coal resources, accounting for more than 90 % of all ascertained fossil energy reserves. The consumption share of coal energy reaches 56.5 % in 2021. Due to the high moisture content of low-rank coal, it is easy to cause equipment blockage in the dry sorting process. This paper considers low-rank coal coming from Inner Mongolia (NM samples) and Yunnan (YN samples). The weight loss performance of the samples was analyzed using thermogravimetric experiments to determine the appropriate temperature for drying experiments. Thin-layer drying experiments were carried out at different temperature conditions. The drying characteristics of low-rank coal were that the higher the drying temperature, the shorter the drying completion time; the smaller the particle size, the shorter the drying completion time. The effective moisture diffusion coefficient was fitted using the Arrhenius equation. The effective water diffusion coefficient of NM samples was 5.07·10–11 - 9.58·10–11 m2/s. The effective water diffusion coefficients of the three different particle sizes of YN samples were 1.89·10–11 - 4.92·10–11 (–1 mm), 1.38·10–10 - 4.13·10–10 (1-3 mm), 5.26·10–10 - 1.49·10–9 (3-6 mm). The activation energy of Inner Mongolia lignite was 10.97 kJ/mol (–1 mm). The activation energies of Yunnan lignite with different particle sizes were 17.97 kJ/mol (–1 mm), 33.52 kJ/mol (1-3 mm), and 38.64 kJ/mol (3-6 mm). The drying process was simulated using empirical and semi-empirical formulas. The optimal model for Inner Mongolia samples was the Two-term diffusion model, and Yunnan samples were the Hii equation was used.
Five colored diamonds were investigated. According to the results of the study by FTIR, UV-Vis-NIR and Photolumines-cence spectroscopy, they are natural type Ia diamonds. The depth distribution of the color intensity was carried out by meas-uring the intensity of the PL peak at 741 nm (GR1 center) upon excitation by a laser with a wavelength of 633 nm of Raman Confocal microscope. To minimise the perturbation due to geometrical effects, defect distribution profiles were normalised with respect to diamond Raman peak intensity (691 nm) point by point. For two diamonds, the intensity of the GR1 peak (741 nm) sharply decreased to a depth of 10 µm, and then became equal to the background level, which is typical for irradia-tion with alpha particles from natural sources like uranium. In other diamonds, the profiles vary slightly with depth, and the color intensity is close to uniform, which is for irradiation with accelerated electrons or neutrons. The source of radiation has not been determined. However, long duration radioactivity measurements of the diamonds suggested that neutrons were not used for colour centers production in the diamonds studied.
Microstructural features of the main rock-forming minerals of host ultramafic rocks (olivine, orthopyroxene) and chrome spinel from ores of the Almaz-Zhemchuzhina deposit were studied using the electron backscatter diffraction method. For ultramafic rocks, statistical diagrams of the crystallographic orientation of olivine and orthopyroxene were obtained, indicating the formation of a mineral association in conditions of high-temperature subsolidus plastic flow in the upper mantle. The main mechanisms were translation gliding and syntectonic recrystallization. Olivine deformation occurred predominantly along the (010)[100] and (001)[100] systems. The textural and structural features of chromitites reflect plastic flow processes, most pronounced in lenticular-banded ores. Microstructure maps in inverse pole figure encoding show differences in the grain size composition of the ores: areas consisting of disseminated chromitites are characterized by a finer-grained structure compared to lens-shaped segregations of a massive structure. Analysis of microstructure maps shows that during the transition from disseminated to massive ores, there is a widespread development of recrystallization, adaptation of neighbouring grains to each other, resulting in homogenization of crystallographic orientation in aggregates. The data obtained develop ideas about the rheomorphic nature of chromitite segregations in ophiolite dunites. It is assumed that the coarsening of the structure of massive chromitites is critically associated with an increase in the concentration of ore grains during solid-phase segregation within a plastic flow, when individual chrome spinel grains, initially separated by silicate material, begin to come into direct contact with each other.
The results of geochemical analysis of organic matter and oils of the Proterozoic (RF-V complex) and the Paleozoic (productive intervals D2, D3, C1-2) of the eastern part of the Volga-Urals oil and gas basin are considered. The data obtained are supported by the results of 2D basin modeling for four regional profiles, two of which are located in the Kama and two in the Belsk parts of the Kama-Belsk aulacogen. Previously obtained data on the degree of catagenetic transformation of the oil and gas source strata of the Riphean-Vendian oil and gas complex were corrected, and catagenetic maps were generated. New evidence is provided for the presence of Precambrian oils in productive Paleozoic complexes. The studied oils are mixed, they are formed due to the generation products of oil and gas source strata of the Riphean, Vendian and Paleozoic (Devonian and Early Carboniferous). Based on the modeling results, it was revealed that the main oil and gas source strata in the RF-V complex of the Kama part of the Kama-Belsky aulacogen are deposits of the Kaltasinskaya formation of the Lower Riphean and the Vereshchaginskaya formation of the Upper Vendian, in Belskaya part -- the strata of the Kaltasinskaya, Kabakovskaya, Olkhovskaya, Priyutovskaya, Shikhanskaya and Leuzinskaya formations of the Riphean and Staropetrovskie deposits in the Vendian. It has been established that the increase in the interval of the main zone of oil and gas formation occurs in the southeast direction. In both depressions of the Kama-Belsky aulacogen, a unified oil system is identified, functioning in deposits of the stratigraphic interval from the Riphean to the Lower Carboniferous. In its composition, the Riphean-Vendian strata are considered as the main oil and gas source strata, the reservoirs are confined to the Riphean carbonate complex, terrigenous deposits of the Upper Vendian and Middle Devonian, and the Upper Devonian-Tournaisian rocks serve as the seal.
The purpose of research is the study of stress-strain state of marginal rock mass around the stope and predictive assessment of ore dilution with regard for changes in ore body thickness in mining thin ore deposits on the example of the Zholymbet mine. Study of the specific features of the stress-strain state development was accomplished applying the methodology based on numerical research methods taking into account the geological strength index (GSI) which allows considering the structural features of rocks, fracturing, lithology, water content and other strength indicators, due to which there is a correct transition from the rock sample strength to the rock mass strength. The results of numerical analysis of the stress-strain state of the marginal part of the rock mass using the finite element method after the Hoek – Brown strength criterion made it possible to assess the geomechanical state in the marginal mass provided there are changes in ore body thickness and to predict the volume of ore dilution. It was ascertained that when mining thin ore deposits, the predicted value of ore dilution is influenced by the ore body thickness and the GSI. The dependence of changes in ore dilution values on the GSI was recorded taking into account changes in ore body thickness from 1 to 3 m. Analysis of the research results showed that the predicted dimensions of rock failure zone around the stopes are quite large, due to which the indicators of the estimated ore dilution are not attained. There is a need to reduce the seismic impact of the blasting force on the marginal rock mass and update the blasting chart.
Operation of vertical mine shafts in complex mining and geological conditions is associated with a number of features. One of them is a radial displacement of the concrete shaft lining, caused by the influence of mining pressure on the stress-strain state of the mine workings. A rigid reinforcing system with shaft buntons fixed in the concrete lining thus experiences elastoplastic deformations, their value increases with time. It results in deviation of conductors from design parameters, weakening of bolt connections, worsening of dynamic properties of geotechnical system “vehicle – reinforcing”, increase of wear rate of reinforcing system elements, increase of risks for creating an emergency situation. The article offers a comprehensive assessment of displacements of characteristic points of the bunton system based on approximate engineering relations, numerical modeling of the deformation process of the bunton system and laser measurements of the convergence of the inner surface of the concrete shaft lining. The method was tested on the example of the reinforcing system of the skip-cage shaft of the potash mine. Displacement of the characteristic points of the reinforcing system is determined by the value of radial displacements of the surface of the concrete shaft lining. Evaluation of the radial displacements was made using monitoring measurements and profiling data. The results obtained make it possible to justify the need and timing of repair works. It is shown that the deterioration of the reinforcing system at different levels occurs at different rates, defined, among other things, by mechanical properties of the rock mass layers located at a given depth.
The first results of mineralogical and geochemical studies of a unique xenolith of lithospheric mantle are presented illustrating the earlier non-described mineral association of quartz, Cr-pyrope and Cr-diopside. Structural and textural features of the sample suggest a joint formation of these minerals. The calculated P-T-parameters of the formation of Cr-diopside indicate the capture of xenolith from the depth interval ~ 95-105 km (31-35 kbar) corresponding to the stability field of coesite. This suggests that quartz in the studied xenolith can represent paramorphs after coesite. It was shown that quartz in this rock is not a product of postmagmatic processes. The transformation stage of the source lherzolite into garnet- and clinopyroxene-enriched rock/garnet pyroxenite as a result of exposure to a high-temperature silicate melt was reconstructed. Subsequent stages of the influence of metasomatic agents were identified by the presence of a negative Eu-anomaly in some garnet grains, which could result from the impact of subduction-related fluid and the enrichment of rock-forming minerals with light rare earth elements, Sr, Th, U, Nb and Ta as a consequence of fluid saturated with these incompatible elements. Several models for the formation of SiO2 phase (quartz/coesite) in association with high-chromium mantle minerals are considered including carbonatization of mantle peridotites/eclogites and melting of carbonate-containing eclogites at the stage of subduction and the impact of SiO2-enriched melt/fluid of subduction genesis with peridotites of the lithospheric mantle.
The paper considers an approach to localizing the intervals of development of geomechanical processes in underground structures based on the classification and transformation of seismic data. The proposed approach will make it possible to identify the intervals of fracturing, rock decompression, water inflow and other geomechanical processes when interpreting the results of seismic surveys. The technique provides for the formation of matrices of longitudinal (Vp), transverse (Vs) velocities and velocity ratios (Vs/Vp) along the research profile to perform sequential filtration. The filtration results serve as the basis for the formation of a bank of informative materials for further classification. Based on the domestic KOSKAD 3D software, four approaches have been implemented for a combined digital model of the Vp, Vs and Vs/Vp parameters. One of the key elements in the classification process is to combine grids to increase the probability of detecting intervals with heterogeneous identification features. The result of the application of this methodical approach is the construction of a comprehensive interpretative model, on which potential zones of geomechanical risks development are clearly manifested.
The selection of efficient drilling and blasting technology to achieve the required particle size distribution of blasted rock mass and reduce ore dilution is directly related to the accurate definition of rock mass properties. The zoning of the rock massif by its hardness, drillability and blastability does not consider the variability of the geological structure of the block for blasting, resulting in an overestimated specific consumption of explosives. The decision of this task is particularly urgent for enterprises developing deposits with a high degree of variability of geological structure, for example, at alluvial deposits. Explosives overconsumption causes non-optimal granulometric composition of the blasted rock mass for the given conditions and mining technology. It is required to define physical and mechanical properties of rocks at deposits with complex geological structure at each block prepared for blasting. The correlation between the physical and mechanical properties of these rocks and drilling parameters should be used for calculation. The relation determined by the developed method was verified in industrial conditions, and the granulometric composition of the blasted rock mass was measured by an indirect method based on excavator productivity. The results demonstrated an increase in excavation productivity, thus indicating the accuracy of given approach to the task of identifying the rocks of the blasted block.
One of the biggest issues in the mining sector is due to acid mine drainage, especially in those abandoned mining operations and active ones that fail to adequately control the quality of their water discharge. The removal degree of copper, iron, lead, and zinc dissolved metals in acid mine drainage was investigated by applying different proportions of mixtures based on neutralizing reagent hydrated lime at 67 % calcium oxide (CaO), with adsorbent material – natural sodium bentonite, compared to the application of neutralizing reagent without mixing, commonly used in the neutralization of acid mining drainage. The obtained results show that the removal degree of dissolved metals in acid mine drainage when treated with a mixture of neutralizing reagent and adsorbent material in a certain proportion, reaches discharge quality, complying with the environmental standard (Maximum Permissible Limit), at a lower pH than when neutralizing material is applied without mixing, registering a net decrease in the consumption unit of neutralizing agent express on 1 kg/m3 of acid mine drainage. Furthermore, the sludge produced in the treatment with a mixture of the neutralizing reagent with adsorbent material has better characteristics than common sludge without bentonite, since it is more suitable for use as cover material, reducing the surface infiltration degree of water into the applied deposit.
The article presents the results of coupled palynological and geochemical studies of five various genesis lakes, located along the route of the expedition “In the footsteps of Alexander von Humboldt in Siberia, Altai and Eastern Kazakhstan”, dedicated to the double anniversary: the 190th anniversary of the expedition across Russia of the famous scientist and his 250th birthday. A geochemical analysis of water and bottom sediments of Ik Lake (Siberia), Lakes Kolyvanskoe and Beloe (Altai), Lake Bezymyannoe (Kazakhstan) and Nagornyi Pond (Altai) was carried out. Based on their results an assessment of studied lakes ecological state was given through single and integral criteria. A high level of pollution was noted for Nagornyi Pond and Lake Bezymyannoe, which is caused by a significant technogenic load from nearby mines. This is consistent with the data of palynological research. The aquatic ecosystems of Lakes Kolyvanskoe and Beloe are characterized by a satisfactory ecological situation, but they experience an increased recreational load. The results of spore-pollen analysis and analysis of non-pollen palynomorphs showed the low ability of these lakes to self-healing. The most favorable ecological state and high self-cleaning capacity were noted for Lake Ik, which is consistent with the data of palynological studies. It is being confirmed with the results of palynological studies. It was therefore concluded about the ability to make a quick assessment of the aquatic ecosystems’ ecological state by studying lakes using coupled palynological and geochemical analysis.
This article describes operations from the well construction cycle where the cement rock behind the casing is subjected to dynamic action (impacts of the drill stem during drilling and normalization of the cement sleeve, secondary drilling operations, hydraulic fracturing, etc.). The developed cement mortar compositions were tested following API 10B-2, API 10B-6, API STD-65-2, and GOST 28985-91 standards. The composition of the cement system without the use of imported components (CM-5) was developed, which improved elastic and strength properties compared to existing industry solutions. An improvement in the elastic and strength features and technological properties of cement rock when using epoxy resins was identified, the optimal composition of the cement-and-epoxy grout was determined, and the internal structure of the formed backfill rock, its permeability, and porosity were studied.
The article presents a study of the Earth’s crust and upper mantle in the Pechenga ore region, as well as areas adjacent to it in the northwestern part of the Kola region. Applying the receiver function technique to data acquired by three broadband seismic stations, we obtained one-dimensional seismic velocity distribution models to a depth of 300 km. The stations are located in the northern parts of Finland and Norway, as well as in the Pechenga region of the Russian Federation. Despite the stations being in relatively close proximity (within 100 km of each other), the velocity models turned out to be significantly different, which indicates structural discontinuity within the lithosphere. Thus, Finland station data set revealed a gradient crust-mantle transition, which is not present in the other two models. At depths of about 150 km, a low-velocity zone was discovered, associated with mid-lithospheric discontinuity, which was not found beneath the Pechenga ore region. Furthermore, the crustal structure of the Pechenga region has an anomalously high Vp/Vs ratio to a depth of about 20 km. Considering the fact that the Pechenga (Nikel) seismic station was installed in close proximity to major copper-nickel deposits, this anomaly can be interpreted as a relic of Proterozoic plume activity.
This study analyzes how key factors impact friction rock bolt capacity using standard pull-out tests, focusing on 39 mm diameter, 180 cm long split-tube bolts. We investigate bolt performance dependence on rock mass rating (RMR), time after installation, schistosity orientation, surface roughness, and installation quality. The aim is optimizing bolt design and implementation for enhanced underground stability and safety. Results show RMR strongly exponentially correlates with pull-out resistance; higher quality rock masses increase capacity. Anchorage capacity significantly rises over time, especially for RMR above 70. Increasing angle between bolt axis and rock foliation from 0 to 90° boosts pull-out response. Reducing borehole diameter below bolt diameter grows bolt-ground friction. Empirical models estimate load capacity based on RMR, time, orientation, diameter, roughness and installation quality. These reliably predict bolt performance from site conditions, significantly improving on basic RMR methods. Experiments provide practical friction bolt behavior insights for typical rock masses. The data-driven analysis ensures models are applicable to actual underground scenarios. This enables tailored optimization of bolting configurations and supports. Methodologies presented should improve safety, efficiency and cost-effectiveness of reinforced mining and tunneling. Overall, this study fundamentally furthers friction bolt performance understanding, enabling superior underground support design.
Increasing amount of apatite-nepheline ores with complex mineral composition involved in processing, growing content of the associated minerals in ore which are similar in their floatability to apatite lead to the necessity of using highly selective collectors. Non-frothing flotation method gave a comparative assessment of floatability of pure minerals and demonstrated a high selectivity of the action of phosphoric acid esters in relation to apatite. The effect of four reagent modes differing in the number of selective synthetic collectors was studied using the example of flotation of an apatite-nepheline ore sample containing 17.27 % apatite and 40.18 % nepheline. Mineralogical analysis of crushed ore showed that it contained two apatite varieties – coarse-grained free and finer poikilitic as inclusions in rock-forming minerals. Free apatite opens and occurs as open grains even in coarse-grained (+0.16 mm) grades. Poikilitic apatite occurs as intergrowths with different minerals, mainly with nepheline and its alteration products (natrolite, spreustein, sodalite, etc.), and pyroxene. Optical microscopy demonstrated that a growing share of reagent from the phosphoric acid oxyethylated esters class in the composition of the collector mixture allows improving the quality of the produced apatite concentrates by reducing the number of apatite intergrowths with nepheline and pyroxenes in the concentrates. In the concentrate obtained in the most selective reagent mode, the intergrowths are characterized by a 50/50 and higher ratio in favour of apatite. Concentrates of lower quality comprised intergrowths with lower apatite content, to 20/80 or less.
A unique Mn-, Cd-bearing sphalerite from quartz-calcite veins in the coal-bearing series (Visean C1v) marine sediments in a 50 km segment of the middle course of the Silova-Yakha River in the Arctic zone of the European part of Russia (Pai-Khoi Ridge) has been studied. The veins have a conformable and cross-cutting occurrence in two types of rocks: gray limestones and black siliceous-carbonaceous shales, the area is known as the Goniatite occurrence. The sulfide content in vein samples ranges from 0.1 to 2 vol.%. The chemical composition of 27 monomineral samples of Mn-, Cd-bearing sphalerites was studied, 82 points were analyzed. Correlations between typomorphic elements-impurities were revealed and correlation matrix was constructed. Cu, V, Ga, In, Sn, As, Sb, Bi, Pb, Tl, Se, Ag, Au, Ni are positively correlated with each other; Cd, Mn and Ge are negatively correlated with each other. The hydrothermal fluid involved in crystallization of sphalerite is characterized by low temperature (164-211 °С) and average salinity of 5-6 wt.% eq. NaCl. An updated “portrait” of typomorphic features (composition and properties) of sphalerite of the Pai-Khoi province was obtained. The features allowing to determine the type of impurity entering the sphalerite structure – in the form of isomorphic impurity or in the form of microinclusions of paragenetic association minerals – have been established. Submicron inclusions of sulvanite and colusite, invisible by other methods, were detected in sphalerite (by LA-ICP-MS method).The cathodoluminescence data of sphalerite from the Pai-Khoi province were typified. In contrast to other provinces, ZnS crystals here are characterized by almost complete absence of isomorphic iron. This allowed us to study pure isomorphism schemes of ZnS↔MnS, ZnS↔CdS, namely cathodoluminescence and other types of luminescence. The presence of a rare wurtzite-4H polytype in assemblage with sphalerite was revealed. High contents of strategic metals Cd, Ga, In, Ge in the ZnS matrix, as well as sulvanite (V, Cu) in a single paragenesis were found. A serious reassessment of the potential for industrial use of this mineralization will be required.
Well killing operation remains an important technological stage before well workover or servicing, during which filtrate penetrates the bottomhole area of the formation. The impact of process fluids and their filtrate on rock has a significant influence on permeability and porosity of carbonate reservoirs, which decrease due to fines migration. There are few known scientific studies of the interaction of killing fluid filtrate with carbonate rock and fines migration. In our experiments, an aqueous phase was used which is the basis for well killing in pure form, for the preparation of blocking agents and is used in reservoir pressure maintenance system. Core samples taken from the pay of the reservoir were used to simulate the well killing process with generation of reservoir thermobaric conditions. Killing fluid filtrate was kept for seven days, which characterizes the average workover time at flowing wells in the fields of the Perm Territory. Using micro-X-ray tomography and scanning electron microscope, images were obtained before and after the experiment, which allowed confirming a decrease in total number of voids due to fines migration and, as a consequence, a decreasing permeability of samples. Measurement of pH and fines concentration in the aqueous phase was performed before and after the experiment and pointed to mineral reactions occurring as a result of rock dissolution. The results of experiments made it possible to record a decrease in permeability of carbonate samples by an average of 50 % due to clogging of void space and migration of fines (clayey and non-clayey).
Landslides are one of the most frequent natural disasters that cause significant damage to property in Vietnam, which is characterized by mountainous terrain covering three-quarters of the territory. In 17 northern mountainous provinces of the country, over 500 communes are at a high to very high landslide hazard. The main goal of this study was to establish landslide hazard maps and conduct a comparative evaluation of the efficiency of the methods employed in Tinh Tuc town, Cao Bang province. The landslide hazard assessment was carried out in this study using the combined Fractal-frequency ratio (FFR) and the Frequency ratio (FR) methods. The FR method is based on the actualist principle, which assumes that future landslides may be caused by the same factors that contributed to slope failure in the past and present. The FFR method is based on the determination of the fractal dimension, which serves as a measure of the landslide filling density in the study area. Eight landslide-related factors were considered and presented in cartographic format: elevation, distance to roads, slope, geology, distance to faults, land use, slope aspect, and distance to drainage. Determining the area under the receiver operating characteristic curve (ROC-AUC) and verification index (LRclass) was performed to assess the performance of prediction models and the accuracy of the obtained maps. As a result, five zones were identified for the study area, characterized by very low, low, moderate, high, and very high landslide hazards. The analysis of the reliability of the obtained landslide hazard maps using the AUC and LRclass indices revealed that the FFR model has a higher degree of reliability (AUC = 86 %, LRclass = 86 %) compared to the FR model (AUC = 72 %, LRclass = 73 %); therefore, its use is more effective.
Directions for the technical and technological development of aluminium industry, existing and promising projects to reduce the energy consumption and the environmental impact are analyzed. The active participation of the state in the organization of financial instruments for the ecological reconstruction of obsolete production facilities is discussed. In spite of the fact that the technology of aluminium pots is developed towards the increase of a single capacity, but with limited potential of reducing energy consumption and greenhouse gases emission, the possibilities for the increase of specific output are practically non-existent. Therefore, such projects like pots, equipped with inert anodes and drained cathodes arise and are under development, the successful completion of which is unlikely after multi-year researches and pilot tests. To continue the works related to inert anodes the decisive answer about the industrial safety of local sources of the massive oxygen emissions to atmosphere is required from competent entities. The drained cathode project, after discussing the existing problems, seems unfeasible. As opposed to the existing technology the development of the pots with vertical electrodes offers great opportunities to the designs of inert anodes and drained cathodes. Positive results of using shaped electrodes, homogenizing their surface and developing the methods for the synthesis of composite cathodes directly during the electrolytic process were obtained in laboratory conditions. It is expected that the combination of these trends and the successive dimensional scaling shall allow using the vertical electrodes at the next level for the fold increase of specific pot capacity and for the decrease of energy consumption and greenhouse gas emissions.
Long-term activity of mining enterprises causes the necessity to substantiate the strategies of management of the mining and technical system functioning in terms of improvement of ore quality control, which is determined by its change in the course of field development due to the priority development of the main reserves and, as a consequence, forced transition to the mining of complex structural rock blocks with a decrease in the recovery percentage, which is typical in case the ore component meets the requirements of the feasibility study in terms of grade at substandard capacity. In this case, it is possible to identify the recovery percentage and the potential for its increase by analyzing the long-term activity of the mining and industrial enterprise, namely, by analyzing the data of mining complex structural rock blocks with the subsequent establishment of the relationship between the primary data on mining and geological conditions and information on the quality of the mineral obtained from the technological equipment. Therefore, the purpose of the research was to substantiate the necessity of improving the management strategy of the mining-technical system functioning, which consists in the fact that on the basis of analyzing the mining data of complex structural rock blocks it is possible to determine the ore mass losses and their quantity and to lay the basis for the development of decisions on its extraction. For this purpose, the collected data on the mining of complex structural rock blocks, accounting the geological and industrial type of extracted ores, were considered in modeling the conditions and studying the parameters of technological processes, the implementation of which provides additional products. It was revealed that the ore mass from substandard thickness layers is delivered to the dumps, and ore mass losses have been estimated at 25-40 % per year. It is proved that determination of ore mass losses based on the analysis of data on mining of complex structural rock blocks, as well as timely solution of this issue can significantly increase the production efficiency of mining and technical system. Taking into account for the results obtained, the options for optimizing the production of the mining and engineering system were proposed.
In oil and gas reservoirs with significant hydrocarbon columns the dependency of the initial hydrocarbon composition on depth – the compositional gradient – is an important factor in assessing the initial amounts of components in place, the position of the gas-oil contact, and variations of fluid properties throughout the reservoir volume. Known models of the compositional gradient are based on thermodynamic relations assuming a quasi-equilibrium state of a multi-component hydrodynamically connected hydrocarbon system in the gravity field, taking into account the influence of the natural geothermal gradient. The corresponding algorithms allow for calculation of changes in pressure and hydrocarbon fluid composition with depth, including determination of the gas-oil contact (GOC) position. Above and below the GOC, the fluid state is considered single-phase. Many oil-gas-condensate reservoirs typically have a small initial fraction of the liquid hydrocarbon phase (LHC) – scattered oil – within the gas-saturated part of the reservoir. To account for this phenomenon, a special modification of the thermodynamic model has been proposed, and an algorithm for calculating the compositional gradient in a gas condensate reservoir with the presence of LHC has been implemented. Simulation cases modelling the characteristic compositions and conditions of three real oil-gas-condensate fields are considered. The results of the calculations using the proposed algorithm show peculiarities of variations of the LHC content and its impact on the distribution of gas condensate mixture composition with depth. The presence of LHC leads to an increase in the level and possible change in the type of the fluid contact. The character of the LHC fraction dependency on depth can be different and is governed by the dissolution of light components in the saturated liquid phase. The composition of the LHC in the gas condensate part of the reservoir changes with depth differently than in the oil zone, where the liquid phase is undersaturated with light hydrocarbons. The results of the study are significant for assessing initial amounts of hydrocarbon components and potential efficiency of their recovery in gas condensate and oil-gas-condensate reservoirs with large hydrocarbon columns.
The Norilsk deposits, unique both in their geological structure and reserves of nickel and platinum, have attracted the attention of researchers for several decades. Several hypotheses have been proposed to explain their formation. Two of them are the most widely accepted: the model of ore formation in an intermediate chamber from picritic melt enriched in sulphides and the formation of sulphides in situ through the assimilation of sulphate-bearing sediments by tholeiitic magma as it rises to the surface. The main questions regarding the genesis of these deposits are: the composition of the parental magmas that formed the ore-bearing massifs; the relationship between intrusions and effusive rocks; and the extent and role of assimilation of host rocks by magmas. These issues are discussed in the article using a large amount of analytical data obtained by the author during the study of the magmatic rocks and geological structures in the Norilsk area. Based on these data, it was concluded that none of the proposed models could fully explain all observed geological features of the deposits as well as the appearance of the unique sulphide ores. In order to solve the problem of the genesis of the Norilsk deposits, it is necessary to analyse the evolution of P3-T1 magmatism over time in the Siberian large igneous province, especially in its eastern part, and to determine its association with ore-forming processes; and its investigating it is a priority task for understanding sulphide ore formation. Solving this task should be based not only on geophysical data but also on studies of the geochemistry of igneous rocks within the province.
The article describes the methodology for laboratory studies of reservoir rock exposure to hydrogen. The stages of sample research and the instruments used in the experiments are considered. A comparative analysis of the results of studies on porosity and permeability of core samples was performed. It was shown that after exposure to hydrogen, the porosity decreased by 4.6 %, and the permeability by 7.9 %. The analysis of correlation dependencies demonstrated a typical change in the relationship of these characteristics: after the samples exposure to hydrogen the scatter of the values increased and the correlation coefficient decreased, which indicates a change in the structure of the void space. Based on the research results, it was concluded that the decrease in porosity and permeability of the core samples occurred due to their minor compaction under the action of effective stresses. The chemical analysis of the rock showed no major difference in the composition of the basic oxides before and after exposure to hydrogen, which points to the chemical resistance of the studied formation to hydrogen. The experimental results showed that the horizon under consideration can be a storage of the hydrogen-methane mixture.
The low-quality petcoke does not find qualified application and is stockpiled at refineries or used as solid fuel. One of the promising ways to use low-quality petroleum coke is its physical or chemical activation in order to obtain a highly porous carbon material that can be used as a catalyst carrier, adsorbent, base for electrodes, etc. The possibility of using petroleum coke to produce sorbent for organic compounds was studied. The activated petroleum cake was obtained by chemical activation with KOH, a specific surface area is 1218 m2/g. Sorption of ethyl alcohol was studied at temperatures 285, 293 and 300 K. It is a physical process proceeding mainly in pores of activated petroleum coke, also sorption can be described as a reversible exothermic process. The effective Gibbs energy at a temperature of 293 K is –12.74 kJ/mol, the heat of sorption is –26.07 kJ/mol. The obtained data confirm that porous carbon material obtained from petroleum coke can be used as sorbent for ethanol at room temperature. For example, for adsorption of bioethanol from the effluent of the fermentation process or for purification of wastewater from organic compounds.
Based on the isotopic-geochemical analyses of zircons from granites of the Belokurikhinsky massif in the Gorny Altai using the U-Pb method, the ages of three intrusion phases have been determined for the first time: the age of the first phase refers to the time interval of 255-250 Ma, the second and the third phases have similar ages of about 250 Ma. The formation time of the Belokurikhinsky massif is estimated as not exceeding 5-8 Ma. The δ18O values for zircons from granites of the second and the third intrusion phases average around 11.5-12.0 ‰, indicating a significant contribution of a crustal component in the formation of the parent melts for granites of these phases. The crystallization temperature values of the zircons by the Ti-in-zircon thermometer for three phases range from 820 to 800 °C. The P-T crystallization parameters of titanite from the first phase, determined using a titanite thermobarometer, average around 770 °C and 2.7 kbar. The zircons from the first phase mostly exhibits geochemical characteristics of typical magmatic zircons. The zircons from the second and the third intrusion phases either may be unaltered magmatic zircons or enriched in incompatible elements (LREE, Th, U, Ti, Ca, etc.) due to fluid influence, resembling hydrothermal-metasomatic type zircons in terms of their geochemical characteristics. A number of zircon grains from the second and the third phases of granites demonstrate anomalous geochemical characteristics – the REE distribution spectra atypical for zircons (including “bird's wing” type spectra with oppositely tilted of light and heavy REE distribution profiles), as well as significantly higher contents of certain trace elements compared to other varieties. Such an enriched zircon composition and wide variations in the incompatible element content are due to non-equilibrium conditions of zircon crystallization and evolution of the fluid-saturated melt composition during the final stages of the massif formation.
