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Date submitted2023-10-28
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Date accepted2024-11-07
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Date published2025-02-25
Radiation characteristics of coals at different stages of metamorphism
The formation of deposits and subsequent metamorphic processes that affect concentrations of radioactive elements in coal can indicate ongoing geological activities, therefore, analyzing trends in the radiation characteristics of coal throughout the metamorphic series is highly relevant. The aim of this work is to experimentally evaluate the radiation characteristics of different coal ranks (metamorphic stages) using thermoluminescent (TL) dosimetry and beta activity measurements, and to identify correlations between these radiation characteristics and data obtained from technical, elemental, and thermogravimetric analyses, as well as mass spectrometric and electron paramagnetic resonance spectroscopy (EPR) measurements. For dosimetric measurements that indirectly characterize the content of radionuclides in coal, a modified dosimetric complex and original soil-equivalent thermoluminescent detectors based on SiO2 were used. The analysis of the obtained results supports the use of TL studies to determine the ash content of coals at low and medium stages of metamorphism (coal rank B→G), while indicating that this method is not feasible for coals at higher stages of metamorphism. The correlation dependencies in the metamorphism series suggest abrupt change in the conditions of coal formation during the time range corresponding to transformation from high to low volatile bituminous coals (coal rank G→Zh→K). These abrupt changes in regional metamorphism conditions (time, temperature, pressure, oxidation-reduction conditions) are confined to the boundary of the Permian and Triassic periods (~250 million years ago), during which both the transformation of existing coal deposits and the formation of new deposits occurred.
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Date submitted2024-05-30
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Date accepted2024-10-14
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Date published2024-11-12
Thermodynamic modelling as a basis for forecasting phase states of hydrocarbon fluids at great and super-great depths
The possibility of discovering oil and gas occurrences at great (more than 5 km) and super-great (more than 6 km) depths is considered in two aspects. The first one is the preservation conditions of large hydrocarbon accumulations forming at depths to 4 km and caused by different geological and tectonic processes occurring at great and super-great depths with partial oil-to-gas transformation. It was ascertained that among the factors controlling preservation of liquid and gaseous hydrocarbons are the temperature, pressure, subsidence rate (rate of temperature and pressure increase), time spent under ultrahigh thermobaric conditions, and initial composition of organic matter. The possibility of existence of liquid components of oil at great and super-great depths is characteristic of sedimentary basins of China, the Gulf of Mexico, the Santos and Campos basins on the Brazilian shelf, and in the Russian Federation it is most probable for the Caspian Depression, some submontane troughs and zones of intense accumulation of young sediments. Determination of critical temperatures and pressures of phase transitions and the onset of cracking is possible using the approach considered in the article, based on estimation of organic matter transformation degree, kinetic and thermobaric models taking into account the composition of hydrocarbon fluid. The second aspect is the estimation of composition of hydrocarbons associated with rocks forming at great depths or rocks transformed under conditions of critical temperatures and pressures. This aspect of considerable science intensity can hardly be considered as practically significant. The study focuses on the investigation of the possibilities of thermodynamic modelling and the use of alternative methods for studying the transformation degree of liquid formation fluid into components of the associated gas through the example of two areas with identified oil, condensate and gas accumulations.
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Date submitted2024-10-29
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Date accepted2024-10-29
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Date published2024-11-12
Study of thermodynamic processes of the Earth from the position of the genesis of hydrocarbons at great depths
In the context of significant depletion of traditional proven oil reserves in the Russian Federation and the inevitability of searching for new directions of study and expansion of the raw material base of hydrocarbon raw materials in hard-to-reach regions and on the Arctic shelf, a scientific search is underway for accumulations in complex geological conditions and in manifestations that differ significantly from traditional ones, which include the processes of oil and gas formation and preservation of oil and gas in low-permeability “shale” strata and in heterogeneous reservoirs at great and super-great depths. Within the oil and gas provinces of the world, drilling of a number of deep and super-deep wells has revealed deposits at great depths, established connections between hydrocarbon deposits and “traces” of hydrocarbon migration left in the core of deep wells, which has made it possible to significantly re-evaluate theoretical ideas on the issue of oil and gas formation conditions and the search for technologies aimed at solving applied problems. Modern geochemical, chromatographic, bituminological, coal petrographic and pyrolytic methods of studying oil and bitumoids extracted from the host rocks of deep well cores give a hope for identifying correlations in the oil-source system, revealing processes that determine the possibility of hydrocarbon formation and accumulation, and defining predictive criteria for oil and gas potential at great depths.
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Date submitted2024-05-13
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Date accepted2024-09-05
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Date published2024-11-12
Potential trace element markers of naphthogenesis processes: modeling and experimentation
With the growing demand for hydrocarbon energy resources, there is a need to involve oil fields at deeper horizons in processing and increase the profitability of their development. Reduction of expenses on prospecting works is possible at revealing and substantiation of physicochemical markers of the naphthogenesis processes. One of the key markers is the transition metals content, which are both a measure of oil age and markers of potential associated processes in the migration and formation of hydrocarbons in the Earth's strata. The elemental composition of samples of oil and reservoir rocks of the Timan-Pechora field was studied. Based on the results of thermodynamic modeling, plausible processes of contact rock minerals transformation were proposed. Based on the results of molecular modeling the probable structure of vanadium and nickel host molecules in the heavy fraction of oils is proposed. The ratios of transition metal and sulfur contents were experimentally established, and assumptions about possible mechanisms of formation of deep hydrocarbon reservoirs were made. Analysis of the obtained ratios of transition metal contents in reservoir rocks and oil samples allowed to suggest possible processes of mantle fluids contact with the host rock and subsequent accumulation of hydrocarbons on sorption active rocks. According to the combined results of experimental and theoretical studies it was found that polymers of heavy fraction more selectively capture vanadium, which indicates the predominance of vanadium content in oil-bearing rocks in relation to the content of nickel. In this case, oil acts as a transport of transition metals, leaching them from the bedrock.
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Date submitted2022-09-05
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Date accepted2023-09-20
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Date published2024-04-25
Modeling the efficiency of seasonal cooling devices when changing the statistical distribution of weather conditions
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.
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Date submitted2023-03-30
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Date accepted2023-09-21
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Date published2023-10-27
Mineral composition and thermobarometry of metamorphic rocks of Western Ny Friesland, Svalbard
The results of the study of mineral composition and microstructure of representative metapelitic and calcic pelitic schist and amphibole-biotite gneiss, occurring in the northern part of the Western Ny Friesland anticlinorium, are reported. Mineral composition was analyzed with a JSM-6510LA scanning electron microscope with a JED-2200 (JEOL) energy dispersive spectrometer. Metamorphic conditions were assessed with various mineral geothermometers (garnet-biotite, Ti-in-biotite, Ti-in-muscovite, Ti-in-amphibole, garnet-amphibole, amphibole-plagioclase, and chlorite) and geothermobarometers (GASP, GBPQ, GRIPS, GBPQ, phengite, etc.). It has been shown that peak temperature and pressure for rocks of the Paleoproterozoic Atomfjella Series forming the western limb of the anticlinorium are consistent with those for the high-pressure part of the upper amphibolite facies (690-720 °С, 9-12 kbar), and the peak temperature and pressure for rocks of the Mossel Series occurring in the eastern limb and rest on the Atomfjella rock sequence, are consistent with the high-pressure part of the lower amphibolite facies (580-600 °С, 9-11 kbar). In addition to the high-temperature parageneses Ms-Bt-Grt-Pl (±Ky, St), Bt-Grt-Pl-Kfs-Cal (±Scp) and Bt-Hbl-Ep-Grt-Pl, the rocks of the both series display the low-temperature assemblage Ms-Chl-Ep-Ab-Prh-Ttn, which was formed upon transition from greenschist to prehnite-pumpellyite facies (260-370 °С).
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Date submitted2022-04-13
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Date accepted2023-02-15
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Date published2023-08-28
The impact of secondary mineral formation on Na-K-geothermometer readings: a case study for the Valley of Geysers hydrothermal system (Kronotsky State Nature Biosphere Reserve, Kamchatka)
The temperature in the Valley of Geysers (Kamchatka) geothermal reservoir calculated using the feldspar Na-K-geothermometer has been steadily increasing over the past 10 years on average from 165 to 235 °C, which is close to the temperature values of a hydrothermal explosion of the steam and water mixture. For the analysis of chemical geothermometers, TOUGHREACT-simulation was used, with the help of which the previously known Na-K feldspar geothermometer was reproduced on a single-element model and new formulas were obtained for three Na-K geothermometers: zeolite, smectite, and based on volcanic glass. Data of chemical analysis for the period 1968-2018, in which the chloride ion is considered as an inert tracer of geofiltration processes, indicates that after 2007 a significant inflow of infiltration water (its mass fraction is estimated from 5 to 15 %) into the Geyser reservoir. It is assumed that the Na-K increased values of the feldspar geothermometer are not the result of the temperature increase in the Geyser reservoir, but the effect of smectite water dilution.
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Date submitted2022-11-06
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Date accepted2022-11-29
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Date published2022-12-29
Technological sovereignty of the Russian Federation fuel and energy complex
- Authors:
- Oleg V. Zhdaneev
The review to achieve technological sovereignty of the Russian fuel and energy complex (FEC) in the ongoing geopolitical situation is presented in the article. The main scope has been to identify the key technology development priorities, restrictions and internal resources to overcome these utilizing the developed by the author the innovative methodology that consists of novel approaches to calculate level of local content, digitalization, business continuity andinteractions with military-industrial complex. Some organizational changes have been proposed to intensify the development of hi-tech products for the FEC and related industries, including establishment of the state committee for science and technology and the project office of lead engineers for the critical missing technologies. Two successful examples to utilize the described in the paper methodology is presented: the first domestic hydraulic fracturing fleet and polycrystalline diamond compact cutter bit inserts.
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Date submitted2021-03-31
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Date accepted2022-04-26
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Date published2022-11-03
Features of obtaining metallurgical products in the solid-state hydride synthesis conditions
- Authors:
- Andrey G. Syrkov
- Lyudmila A. Yachmenova
A scientific substantiation of solid-phase feedstock choice and preparation has been carried out, and the thermodynamic and kinetic aspects of solid-state hydride synthesis (SHS) of metal products have been analyzed using the nickel dichloride reduction as an example. The preliminary dehydration modes and methods for controlling the complete removal of crystalline water from chloride raw materials and Olenegorsk superconcentrate, which is natural oxide raw material, are described. Conditions, including initial solid chloride particle sizes, are established under which diffusion complications of reduction to metal in methyldichlorosilane vapor are minimized. Thermodynamic estimates of nickel chlorides and oxides reduction possibility, iron and copper with ammonia and methane at temperatures of 400-1000 K in equilibrium conditions have been carried out. It has been shown that the stoichiometric coefficients of the nickel dichloride in ammonia overall reduction reaction calculated by thermodynamic modeling are in agreement with experimental data. In contrast to the copper dichloride reduction, for nickel dichloride the formation of metal monochloride at the intermediate stage is uncharacteristic, which is associated with a higher thermal stability of nickel dichloride. The main kinetic regularities of the reduction of nickel, copper, and iron to metal under SHS conditions in ammonia, monosilane, and methane, as well as the nickel dichloride with methyldichlorosilane vapor and methane successive reduction, are considered. Approximation of experimental data by topochemical equations in a linear form showed that for reduction degrees a up to 0.7-0.8, these data are satisfactorily described by the Roginsky – Schultz equation. For a > 0,8 the “shrinking sphere” model works better, which confirms the localization of the solid-state reduction reaction at the interface, moves deep into the crystal with the formation of a of interlocked metal germs. The importance and prospects of the results obtained for the theory development of metallurgical processes, deep complex processing of natural iron oxide raw materials, metal products and new generation materials production, including superhydrophobic ones, are discussed. The relevance of the study from the point of view of applying the method of physical and chemical analysis to the study of complex heterogeneous metallurgical processes is noted.
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Date submitted2021-10-15
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Date accepted2022-09-06
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Date published2022-11-10
Experimental research on the thermal method of drilling by melting the well in ice mass with simultaneous controlled expansion of its diameter
- Authors:
- Danil V. Serbin
- Andrey N. Dmitriev
During the seasonal work of the 64th Russian Antarctic Expedition in 2018-2019 at the “Vostok” drilling facility named after B.B.Kudryashov (“Vostok” station, Antarctic) specialists of Saint Petersburg Mining University conducted experimental investigations on the process of drilling by melting with simultaneous expansion of wells in the ice mass. A test bench and a full-scale model of a thermohydraulic reamer-drilling tool were developed, manufactured and tested for the research. The first bench tests of the full-scale model proved its efficiency and suitability for experimental drilling with simultaneous expansion of wells in ice mass; its operational capabilities were determined and the drawbacks that will be taken into account in future were found out. The article substantiates the choice of constructive elements for thermohydraulic reamer-drilling tool. It is determined that the technology of full diameter drilling with simultaneous expansion of the well in ice mass can be implemented by combining contact drilling by melting and convective expansion with creation of forced near-bottomhole annular circulation of the heated heat carrier. Dependencies of expansion rate on main technological parameters were determined: active heat power of heating elements in penetrator and circulation system, mechanical drilling rate, pump flow rate. According to the results of investigations, the experimental model of thermohydraulic reamer-drilling tool will be designed and manufactured for testing in conditions of well 5G.
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Date submitted2022-03-03
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Date accepted2022-04-27
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Date published2022-07-26
Peculiarities of rare-metal mineralization and genetic relationship of mineral associations in the eastern rim of Murzinsko-Aduysky anticlinorium (the Ural Emerald Belt)
- Authors:
- Mikhail P. Popov
The paper presents features of the location and composition, as well as a generalization of data on the age of rare-metal mineralization developed at the deposits and occurrences of rare metals and gemstones in the eastern rim of Murzinsko-Aduysky anticlinorium, within the Ural Emerald Belt, which is a classic ore and mineralogical object and has been studied for almost two hundred years. With a significant number and variety of prospecting, research and scientific works devoted mainly to emerald-bearing mica complexes and beryl mineralization, as well as rare-metal pegmatites, scientific literature has so far lacked generalizations on the formation of numerous mineral associations and ore formations that represents a uniform genetic process in this ore district. The aim of the work is a comprehensive geological-mineralogical analysis of mineral associations of the eastern rim of Murzinsko-Aduysky anticlinorium and studying their age, formation conditions and characteristic features to determine the possibility of expanding and using the mineral resource base of the Urals through developing new prognostic and prospecting criteria for rare-metal and gemstone ore formations and creating the new devices for promising objects prospecting
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Date submitted2022-04-14
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Date accepted2022-07-21
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Date published2022-07-13
Mullite production: phase transformations of kaolinite, thermodynamics of the process
The growing demand for mullite raw materials, which meet industrial requirements originates the search for new and alternative sources, as well as efficient technologies for obtaining the target products (nanocomposites). The article suggests a method for obtaining mullite from kaolinite experimentally (Vezhayu-Vorykvinsky deposit, Russia). Structural kaolinite transformations (Al-Si-O-Me system), mineral phases transformations, and thermodynamics of the process have been studied. Based on the estimation of the thermodynamics of the reactions, the preferable reaction of mullite formation was determined. The article shows, that formation of the target product, mullite nanocomposite, has several intermediate phases (metakaolinite, pseudomullite). The transformations of the initial kaolinite structure include the removal of structural water and separation of the silica-oxygen tetrahedral and alumina-oxygen octahedral layers, the decomposition into free oxides, breaking of bonds between the silica-oxygen tetrahedrons and the partial increase in the coordination number of aluminium ions, the formation of mullite and cristobalite from free oxides. The proposed approach controls the ratio of Al 2 O 3 and SiO 2 phases at certain stages, which will further improve the mechanical and other properties of the matrix of the obtained raw materials for the target prototypes of industrial products.
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Date submitted2021-11-30
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Date accepted2021-11-30
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Date published2021-12-27
Innovative ways to control dust and explosion safety of mine workings
Ensuring dust and explosion safety during underground coal mining is one of the most important tasks of industrial safety and labor protection departments. The main method of preventing explosions of coal dust settled in mine workings is to process them with stone dust (rock dusting). The traditional methods of quality control of rock dusting include radioisotope, optical and chemical methods. To implement them, the devices are equipped with environmentally harmful radioactive elements, expensive optical sensors, desiccants and replaceable flasks with chemical reagents, which increases the cost of analysis and its duration. The measurement error of these devices is 10 % or more. The main purpose of the study is to develop and substantiate a new method for monitoring the dust and explosion safety of mine workings, which will be devoid of the disadvantages of the methods mentioned above. It is proposed to evaluate the quality of rock-dust distribution by a fundamentally new way – thermogravimetric. The method was tested on the dust of coal mines in Kuzbass and the Vorkuta basin, including dust samples taken in mines with actual explosions. The article presents the results of experimental studies of the processes of thermal destruction of coal and stone dust mixtures. The non-overlapping intervals of the thermogravimetric reaction are identified: moisture yield (35-132 °С); volatile matter yield from coal (380-580 °С); thermal degradation of limestone with carbon dioxide yield (650-850 °С). Methods and mathematical dependencies for processing significant and qualitative identification characteristics of thermogravimetric curves in determining the content of non-combustible components in a sample of mine dust are considered.
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Date submitted2021-06-10
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Date accepted2021-07-27
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Date published2021-10-21
Defects of diamond crystal structure as an indicator of crystallogenesis
- Authors:
- Evgeny A. Vasilev
Based on the study of a representative collections of diamonds from diamondiferous formations of the Urals and deposits of the Arkhangelsk and Yakutian diamond provinces, we established patterns of zonal and sectoral distribution of crystal structure defects in crystals of different morphological types, identified the specifics of crystals formed at different stages of crystallogenesis and performed a comprehensive analysis of constitutional and population diversity of diamonds in different formations. We identified three stages in the crystallogenesis cycle, which correspond to normal and tangential mechanisms of growth and the stage of changing crystal habit shape. At the stage of changing crystal habit shape, insufficient carbon supersaturation obstructs normal growth mechanism, and the facets develop from existing surfaces. Due to the absent stage of growth layer nucleation, formation of new {111} surfaces occurs much faster compared to tangential growth mechanism. This effect allows to explain the absence of cuboids with highly transformed nitrogen defects at the A-B 1 stage: they have all been refaceted by a regenerative mechanism. Based on the revealed patterns, a model of diamond crystallogenesis was developed, which takes into account the regularities of growth evolution, thermal history and morphological diversity of the crystals. The model implies the possibility of a multiply repetitive crystallization cycle and the existence of an intermediate chamber; it allows to explain the sequence of changes in morphology and defect-impurity composition of crystals, as well as a combination of constitutional and population diversity of diamonds from different geological formations.
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Date submitted2021-01-20
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Date accepted2021-03-29
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Date published2021-09-20
Analysis of the causes of engineering structures deformations at gas industry facilities in the permafrost zone
Construction of oil and gas infrastructure facilities on permafrost soils is the most important task of increasing the raw material base of the entire fuel and energy industry in Russia. Permafrost soil is a complex, multicomponent system, state of which depends on many factors. Buildings and structures built under such conditions, on the one hand, have a complex thermal effect on permafrost soils, and on the other hand, they perceive the consequences of changes in the characteristics of such soils. This situation leads to the fact that buildings and structures on permafrost soil during their life cycle are subject to complex and poorly predictable deformations. Article presents the results of a study for various degradation processes of permafrost soils that can be implemented at construction sites of industrial facilities. Analysis of the deformations causes for engineering structures at the gas industry in the permafrost zone is carried out. Series of reasons causing such deformations have been investigated. Comprehensive criterion for assessing changes in permafrost-geological conditions of industrial sites is proposed. It is suggested to apply the method of calculating the individual characteristics for the temperature regime of the territory to monitor and assess the conditions of heat exchange and predict changes in the geocryological conditions of permafrost soil.
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Date submitted2020-06-11
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Date accepted2021-03-30
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Date published2021-06-24
Crystal morphology of spherical viruses
- Authors:
- Yury L. Voytekhovsky
The article discusses modern views on the structure of spherical virus capsids, which have the shape of icosahedrons (icosahedral viruses). Each face of icosahedron is composed of a single-layer closest packing of protein globules, which can have different orientation relative to the edges of icosahedron. If the lines of globules are parallel to the edges of icosahedron, then the capsid has a point symmetry group I h (with symmetry planes), if they are not parallel – the symmetry group I (without planes). From a mathematical point of view, in both symmetry groups there are series that unite equally (up to similarity) arranged capsids. They are connected pairwise by transitions to dual forms (homologous series). A hypothesis is formulated that the largest spherical viruses can have even more diverse and complex capsid structures. Along with icosahedron, their basic forms can be any simple shapes, allowed in I h and I symmetry groups (8 in total). A suggestion is made that transitions within similarity series and between homologous series have a phylogenetic significance. There are known spherical viruses of both symmetry groups. For example, the SARS-CoV-2 coronavirus has a symmetry group I h and belongs to a well-known series. The crystallographic approach allows to construct a strict morphological classification of spherical viruses. This is important for their early recognition and separate examination. The article demonstrates practical application of crystal morphology in the study of viral systems – an urgent problem of geoecology and life protection.
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Date submitted2020-10-22
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Date accepted2021-03-02
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Date published2021-04-26
Dynamic simulation of industrial-scale gibbsite crystallization circuit
- Authors:
- Vladimir O. Golubev
- Tatyana E. Litvinova
Population balance model is crucial for improving the method of aluminum hydroxide massive crystallization and enhancing the quality of control over industrial precipitation trains. This paper presents the updated population balance model, which can be used for simulation of industrial-scale precipitation. Processes of birth-and-spread and particle breakage are considered integral parts of the precipitation process along with secondary nucleation, growth and agglomeration of particles. The conceptual difference of the proposed system of equations is its ability to reproduce the oscillatory process that occurs in precipitation circuits as a result of cyclic changes in the quality of the seed surface. It is demonstrated that self-oscillations can occur in the system without any external influence. The updated model is adjusted and verified using historical industrial data. The simulation of seed-recycle precipitation circuit showed an exact correspondence between the calculated dynamic pattern of changes in particle size distribution of aluminum hydroxide and the actual data.
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Date submitted2020-06-10
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Date accepted2020-11-19
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Date published2021-04-26
Influence of jarosite precipitation on iron balance in heap bioleaching at Monywa copper mine
Ferric iron is an important oxidant in sulfide ore bioleaching. However, recirculating leach liquors leads to excess iron accumulation, which interferes with leaching kinetics and downstream metal recovery. We developed a method for controlling iron precipitation as jarosite to reduce excess iron in heap bioleaching at Monywa copper mine. Jarosite precipitation was first simulated and then confirmed using batch column tests. From the simulations, the minimum pH values for precipitation of potassium jarosite, hydronium jarosite, and natrojarosite at 25 °C are 1.4, 1.6, and 2.7, respectively; the minimum concentrations of potassium, sulfate, ferric, and sodium ions are 1 mM, 0.54, 1.1, and 3.2 M, respectively, at 25 °C and pH 1.23. Column tests indicate that potassium jarosite precipitation is preferential over natrojarosite. Moreover, decreased acidity (from 12 to 8 g/L), increased temperature (from 30 to 60 °C), and increased potassium ion concentration (from 0 to 5 g/L) increase jarosite precipitation efficiency by 10, 5, and 6 times, respectively. Jarosite precipitation is optimized by increasing the irrigating solution pH to 1.6. This approach is expected to reduce the operating cost of heap bioleaching by minimizing the chemicals needed for neutralization, avoiding the need for tailing pond construction, and increasing copper recovery.
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Date submitted2020-01-27
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Date accepted2020-05-22
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Date published2020-10-08
Sorption of rare earth coordination compounds
Rare earth elements (REEs) are valuable and strategically important in many high-technology areas, such as laser technology, pharmacy and metallurgy. The main methods of REE recovery are precipitation, extraction and sorption, in particular ion exchange using various sorbents, which allow to perform selective recovery and removal of associated components, as well as to separate rare earth metals with similar chemical properties. The paper examines recovery of ytterbium in the form of coordination compounds with Trilon B on weakly basic anion exchange resin D-403 from nitrate solutions. In order to estimate thermodynamic sorption parameters of ytterbium anionic complexes, ion exchange process was carried out from model solutions under constant ionic strength specified by NaNO 3 , optimal liquid to solid ratio, pH level, temperatures 298 and 343 K by variable concentrations method. Description of thermodynamic equilibrium was made using mass action law formulated for ion exchange equation and mathematically converted to linear form. Values of equilibrium constants, Gibbs free energy, enthalpy and entropy of the sorption process have been calculated. Basing on calculated values of Gibbs energy, a sorption series of complex REE ions with Trilon B was obtained over anion exchange resin D-403 from nitrate solutions at temperature 298 K. Sorption characteristics of anion exchange resin have been estimated: total capacity, limiting sorption of complex ions, total dynamic capacity and breakthrough dynamic capacity.
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Date submitted2019-03-31
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Date accepted2019-08-25
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Date published2020-02-25
Cascade frequency converters control features
The structures of systems with high-voltage cascade frequency converters containing multi-winding transformers and low-voltage low-power converters connected in series at each output phase of the load are considered. Low-voltage blocks contain three-phase diode or active rectifiers, DC capacitor filters, single-phase stand-alone voltage inverters and block disconnecting devices in partial modes (in case of failure when part of the blocks are disconnected). The possibilities of operation of cascade converters are determined, equations for correcting tasks to units in partial modes are given, tables of correction of tasks with estimates of achievable load characteristics are proposed. The results of experiments on the model of a powerful installation with a cascade frequency converter are presented, confirming the possibility of ensuring the symmetry of the load currents when disconnecting part of the blocks and the asymmetry of the circuit.
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Date submitted2019-05-02
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Date accepted2019-07-09
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Date published2019-10-23
Effect of Temperature on Solid-state Hydride Metal Synthesis According to Thermodynamic Modeling
Thermodynamic modeling of the reduction of copper dichloride in the media of various gaseous hydrides (ammonia, monosilane, methane) in the temperature range 273-1000 K was carried out. Calculations show that in narrower temperature ranges corresponding to the reactions of solid-state hydride synthesis (SHS) of metal sub- stances metal formation is usually supported by theoretical propositions. As a result of thermodynamic modeling, a principal result was obtained on the suppression of competing processes of nitriding, siliconizing and carbonization of metal under SHS conditions, which is important for metallurgical production. This additionally substantiates the correctness of previous experimental studies of SHS metals with modified surface and improved properties. By mod- eling, it was found that the reduction of solid copper dichloride to metal in ammonia or methane occurs stepwise (se- quentially, according to the Baykov rule) through the intermediate stages of the formation of a compound of low- valent copper – copper (I)chloride.
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Date submitted2019-03-05
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Date accepted2019-05-03
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Date published2019-08-23
Efficiency Estimation of the Single- and Multicomponent Anti-hydrate Reagents
- Authors:
- N. A. Shostak
- E. P. Zaporozhets
Different types of technological and technical problems in the oil, gas and chemical industries are connected with the hydrate formation process and with the using of anti-hydrate chemicals. That is why, it is necessary to estimate thermobaric ranges within which reagents does not let hydrate to grow or is their dissociation. Also, to estimate anti-hydrate influence we need to determine the chemicals’ anti-hydrate efficiency and chose the best one. They make the reagents consisting of several chemical components depending on the purpose of their application – for prevention of formation and (or) elimination of hydrates. It demands calculations of the optimum concentration and expenses and also the intensity (speed) of hydrates dissociation causing with the reagents. The analytical method of the anti-hydrate chemical reagents efficiency determination containing one or several components from different classes of chemical compounds – alcohols, salts, acids, compounds of nitrogen and oxygen – is presented in this paper. With its help it is possible to define decrease in temperature of hydrate formation from reagents influence, to count key parameters of reagents anti-hydrate efficiency depending on component compositions of hydrate gas and a phase condition of a hydrate-gas system, to select types of chemical components and their quantity in multicomponent reagents, i.e., to make new compounds. The method can be used for express assessment of anti-hydrate chemical reagents efficiency on criteria sign for practical application in oil, gas and processing industry.
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Date submitted2019-03-17
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Date accepted2019-05-13
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Date published2019-08-23
Manifestations of Acoustic Emission in Frozen Soils with Simultaneous Influence of Variable Mechanical and Thermal Effects on Them
- Authors:
- E. A. Novikov
- V. I. Shkuratnik
- M. G. Zaytsev
The subject of the research is to establish the fundamental laws of acoustic emission in frozen soils, which allow to create ways to control (monitor) their stability under the influence of variable temperature fields and quasistatic mechanical stress from engineering objects located on these grounds for various purposes. The applied importance of such methods is to increase the speed and reduce the complexity of engineering geological surveys in the northern regions of Russia, carried out with the aim of predicting the loss of stability of the bases of buildings and structures to ensure their safe operation. The study was performed on the original instrumental complex. Its description and characteristics are given. With the use of this complex, thermoacoustic emission effects arising from the repeated alternation of freezing and thawing cycles of the soil during the development of its deformed state, starting from the normal compaction phase and up to the final stage of destruction (the bulging phase), have been studied. It is shown that on the basis of such informative parameters as thermally stimulated activity and duration of acoustic emission pulses, an indicator can be obtained that quantitatively characterizes the stages of the stress-strain state of soils. An experimental dependence of the field of values of this indicator as a function of the mechanical stress and the fractional composition of the test soil is given. The qualitative convergence of this dependence with the classical soil deformation diagram obtained by N.M.Hersevanov is shown, where the stages of compaction, loss of stability (shifts) and destruction are highlighted. Possible physical mechanisms and features of the formation of an acoustic emission response at each of these stages are considered and substantiated. It is noted that the approaches to receiving, processing and interpreting acoustic emission measurement information, which are grounded within the framework of the study, allow to control and monitoring of the carrying capacity and stress-strain state of soils directly in the field.
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Date submitted2019-01-13
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Date accepted2019-03-04
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Date published2019-06-25
Thermodynamic model of ion-exchange process as exemplified by cerium sorption from multisalt solutions
A complex heterogeneous process of ion exchange can be defined with an isotherm-isobar equation of the chemical reaction, which describes differential affinity between the process and its effect – the law of mass action. Ion exchange includes processes accompanied by changes in the charge of ions and functional groups caused by the passing of ionic bond into covalent one. Hence isotherm equations of ion exchange for such processes must differ from conventional stoichiometric equations, but they can be obtained by classical study approaches to ion exchange equilibrium. The paper describes a new thermodynamic model, based on linearization of mass action law, modified for the ion exchange equation. The application of this model allows to define stoichiometry of ion exchange and the shape of ions adsorbed by the solid phase of ion-exchange resins, as well as to estimate equilibrium constant and Gibbs free energy of the process. Comparative analysis has been carried out for the thermodynamic model of cerium sorption in the form of anionic complex with Trilon B from a multisalt solution with ionic strength of 1 mol/kg (NaNO 3 ) under рН = 3 and temperature 298 K on a test sample of weak-base anion-exchange resin Cybber EV009. Experimental isotherm of the sorption has been obtained. Calculations of thermodynamic parameters have been performed using Langmuir, Freundlich, Dubinin – Radushkevich, Temkin and Flory – Huggins models, as well as thermodynamic model of linearized mass action law, proposed by the authors. Calculated values of the equilibrium constant and Gibbs energy – K = 9.0±0.5 and ΔrG 0 298 = –5.54±0.27 kJ/mol – characterize the sorption of EDTA cerate ions by ion-exchange resin. The shape of adsorbed ions has been defined in Stern-Helmholtz layer of CeTr, and total capacity of anion resin EV009 for EDTA cerate ions has been estimated as q ∞ = 2.0±0.1 mol/kg.
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Date submitted2018-09-04
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Date accepted2018-11-18
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Date published2019-02-22
Operation experience of centrifugal single-stage pumps in «ALROSA» Joint Stock Company
- Authors:
- N. P. Ovchinnikov
When mining diamond-bearing raw materials and further extracting diamonds from it in the joint-stock company ALROSA, which is a city-forming enterprise in the north-east of the Russian Federation, various pumping equipment is used, in particular, centrifugal single-stage pumps. In the present work, it is noted that the least reliable in terms of absence of failures of centrifugal single-stage pumps used in the joint-stock company ALROSA are the impellers, seals and bearing assemblies. Using linear correlation and regression analysis, it was found that the durability of the seals and bearing assemblies of the investigated pumps largely depends on the durability of their impellers. In the course of research, it was found that unbalancing the pump rotor due to excessive hydroabrasive wear of the impeller also leads to deformation and fracture of the shaft. In general, residual deformations and destructions are characteristic of the shafts of domestic pulp pumps of GrAT, GrT and Gr types. The most loaded sections of shafts of centrifugal single-stage pumps are installed. The most effective from the point of view of application among the pulp (ground, slurry and sand) pumps are pulp pumps of the Finnish company «Metso». When working on highly mineralized water (brines), the «X» type pumps have proven to be the best among centrifugal single-stage pumps.