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Date submitted2023-07-31
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Date accepted2024-11-07
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Date published2025-02-25
Environmental assessment of biochar application for remediation of oil-contaminated soils under various economic uses
- Authors:
- Tatiana V. Minnikova
- Sergey I. Kolesnikov
Remediation is an important area of oil-contaminated soil restoration in Russia, since oil refining industry is the major one for Russia and neighbouring countries, and the issues of environmentally effective and economically profitable remediation of oil contamination have not yet been solved. Soils under various economic uses have different surface areas and degrees of soil particles envelopment with oil due to the presence or absence of cultivation, the amount of precipitation and plant litter. The introduction of various substances for remediation into oil-contaminated soils of steppes (arable land), forests, and semi-deserts, considering their differences, gives different results. Biochar is coal obtained by pyrolysis at high temperatures and in the absence of oxygen. The uniqueness of this coal lies in the combination of biostimulating and adsorbing properties. The purpose of the study is to conduct an environmental assessment of biochar application for remediation of oil-contaminated soils under various economic uses. The article compares the environmental assessments of biochar application in oil-contaminated soils with different particle size fraction. The following indicators of soil bioactivity were determined: enzymes, indicators of initial growth and development intensity of radish, microbiological indicators. We found that the most informative bioindicator correlating with residual oil content is the total bacteria count, and the most sensitive ones are the roots length (ordinary chernozem and brown forest soil) and the shoots length (brown semi-desert soil). The use of biochar on arable land and in forest soil (ordinary chernozem and brown forest soil) is less environmentally efficient than in semi-desert soil (brown semi-desert soil). The study results can serve to develop measures and managerial and technical solutions for remediation of oil-contaminated soils under various economic uses.
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Date submitted2024-04-24
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Date accepted2024-09-24
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Date published2024-11-12
Study and justification of the combination of beneficiation processes for obtaining flake graphite from technogenic carbon-containing dusts
The most important task of modern production development is to provide the mineral and raw materials sector of the economy with resources included in the list of strategic raw materials, including flake graphite. In addition to natural raw materials, the source of its obtaining can be metallurgical production wastes not involved in processing. Development of metallurgical dust beneficiation technology will solve the problem of obtaining high-purity flake graphite with a crystal structure close to ideal and in demand in the production of high-tech materials. It will allow creating a renewable raw material base of graphite and utilising metallurgical production wastes. The research included the study of dust beneficiation by coarseness, magnetic and flotation methods, the influence of dust disintegration processes on beneficiation indicators. Based on the established technological properties of the components of dusts, magnetic, flotation and gravity beneficiation methods can be applied for their separation in different sequence. It is shown that dusts from different sites have different enrichability by these methods, and it should be taken into account when developing a complex technology of their processing. The degree of beneficiation increases in a row of dusts from the blast furnace shop (BF) – electric steel smelting shop (ESS) – oxygen-converter shop (OCS). The method of grinding has a significant influence on the separation indicators – at dry grinding in a centrifugal-impact mill with subsequent pneumatic classification the quality of graphite concentrates increases by 22.7 % of carbon for BF dust and by 13.48 % of carbon for ESS dust. OCS dust beneficiation indicators are high at coarse grinding with steel medium – mass fraction of carbon 96.1 %.
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Date submitted2023-07-05
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Date accepted2024-06-03
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Date published2024-12-25
Complete extraction of conditioned ores from complex-structured blocks due to partial admixture of substandard ores
- Authors:
- Bayan R. Rakishev
The paper presents mining-technological substantiation of complete extraction of conditioned ores from complex-structured blocks of benches by mixing a layer of substandard ores of certain sizes. The relevance of the work consists in the development of innovative methods of establishing the parameters of the substandard layer of ores to be added to the conditioned ores. The main problem is to ensure complete extraction of useful components into concentrate from shipped ore with acceptable deviations from the required ones. A new typification of complex-structured ore blocks of the bench has been carried out. Analytical dependences of mining and geological characteristics of complex-structured ore blocks were obtained. Theoretical dependences for determining the main indicators of mineral processing are derived. Analytical dependences for determination of the content of useful component in shipped ore α' – mixture of conditioned ore with the content of useful component α and admixed layer of substandard ore with the content of useful component α'' are offered. For the first time in mining science, a new approach of complete extraction of conditioned ores from complex-structured blocks of benches by grabbing a certain part of substandard ores during excavation, increasing the volume of extracted ore and expanding the extraction of useful components in the concentrate has been substantiated. The increment of useful components can reach 10-15 % of the total volume of extraction, which allows predicting a significant increase in the completeness of mineral extraction from the Earth's interior.
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Date submitted2021-10-27
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Date accepted2023-06-20
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Date published2023-12-25
Geomechanical analysis of the impact of the new tunnels construction in the vicinity of existing underground subway structures on the state of the soil massif
The specificity of the behavior of the soil massif near the tunnel under construction in difficult mining conditions is considered. It was revealed through the joint interpretation of the results of geophysical measurements in the tunnel and computer simulation. The results of field geophysical studies to identify areas of decompacted soil behind the lining in two existing tunnels during successive drilling of two new tunnels under them are described. A method to analyze the response of the lining to impact was used providing for the calculation of its energy. It has been established that the decompaction zones are mainly located in the lateral lower areas of the tunnel. To substantiate the mechanism of formation of cavities, computer simulations were carried out using the finite element method with the COMSOL Multiphysics software. The finite element model is built on the Drucker – Prager criterion in the variant of a two-dimensional problem statement. It is shown that at the initial position of two old tunnels, the areas of decompaction can develop mainly on the sides. The position of the zones changes significantly when excavating two new tunnels. Soil decompaction zones appear between the tunnels and there is a tendency for the areas to spread to the upper point of the tunnel. According to geophysical data time delays in the impact of new tunnels on the existing line are noted, as well as a decrease in the size of decompacted soil areas over time. There is a satisfactory agreement between the positions of the decompaction areas and voids obtained by the geophysical method and the results of numerical simulation.
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Date submitted2022-05-17
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Date accepted2023-04-03
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Date published2024-02-29
Improvement of concentrate quality in flotation of low-rank coal
- Authors:
- Sergei A. Kondratev
- Tatyana A. Khamzina
Percentage of high-rank coal with low content of ash, moisture, and sulfur in total coal production output is low. Most of the produced coal has a low quality (lignite, bituminous coal: long-flame and fiery). Under increasing requirements for ecological cleanness of coal, the efficient use of coal products is only possible after improvement of their processing properties. The authors discuss the enhancement of flotation efficiency of low-rank coal using the mechanism of physisorption of a collecting agent in particle – bubble attachment. It is explained why the yield of concentrate with low ash content increases as a result of combination of collectors having different physical properties. It is shown that the surface activity of a heteropolar agent relative to the gas – liquid interface and the adsorption density of the agent govern its collecting properties. Based on the recovery – surface activity relationship, the correlation is found between the collecting activity of a chemical compound and the structure of its molecules. The combination of the collectors with different surface activity enables adjusting collectability and selectivity of the blend. The physisorption mechanism of collectors can be a framework for developing recommendations on modification of concentrate yield and ash content, and on selection of optimized ratios of surface activities of miscible collectors relative to the gas – liquid interface.
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Date submitted2022-05-13
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Date accepted2022-09-24
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Date published2022-11-03
Rapid detection of coal ash based on machine learning and X-ray fluorescence
Real-time testing of coal ash plays a vital role in the chemical, power generation, metallurgical, and coal separation sectors. The rapid online testing of coal ash using radiation measurement as the mainstream technology has problems such as strict coal sample requirements, poor radiation safety, low accuracy, and complicated equipment replacement. In this study, an intelligent detection technique based on feed-forward neural networks and improved particle swarm optimization (IPSO-FNN) is proposed to predict coal quality ash content in a fast, accurate, safe，and convenient manner. The data set was obtained by testing the elemental content of 198 coal samples with X-ray fluorescence (XRF). The types of input elements for machine learning (Si, Al, Fe, K, Ca, Mg, Ti, Zn, Na, P) were determined by combining the X-ray photoelectron spectroscopy (XPS) data with the change in the physical phase of each element in the coal samples during combustion. The mean squared error and coefficient of determination were chosen as the performance measures for the model. The results show that the IPSO algorithm is useful in adjusting the optimal number of nodes in the hidden layer. The IPSO-FNN model has strong prediction ability and good accuracy in coal ash prediction. The effect of the input element content of the IPSO-FNN model on the ash content was investigated, and it was found that the potassium content was the most significant factor affecting the ash content. This study is essential for real-time online, accurate, and fast prediction of coal ash.
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Date submitted2021-02-24
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Date accepted2021-10-18
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Date published2021-12-16
A probabilistic approach to the dynamic cut-off grade assessment
Cut-off grade is an important conditioning parameter that determines the quantity and quality of recoverable reserves and development efficiency. Today, Russian mining companies operate with certified quality requirements. By setting permanent quality requirements, the government seeks to prevent depletion of reserves, reduced production during periods of falling prices, and decreased budget revenues, expressing the interests of all members of society. But to what extent do the permanent quality requirements protect the interests of the state? The answer to this question is ambiguous and does not lie on the surface. The State Commission for Reserves and domestic researchers are working to find a rational solution to the problem of quality requirements. One solution is dynamic quality requirements. The effectiveness of their application has been proven for individual mining companies, but it is incorrect to transfer these conclusions to the entire mineral resource base of the country. This article presents a new approach to determining the dynamic cut-off grade, which varies depending on the price of minerals. The dynamic cut-off grade is proposed to be determined based on the indicators of constant requirements to the quality of exploration work, using the maximum allowable costs in the region. The approach allows to calculate the effect of the introduction of dynamic cut-off grade in the practice of subsurface use for the state (in the form of the amount of taxes received) and for subsoil users (in the form of the amount of income). For a group of gold-bearing deposits with open-pit mining method, it was established that the development of reserves using dynamic values of the cut-off grade in periods of price changes ensures compliance with the interests of the state and subsoil users.
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Date submitted2018-05-24
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Date accepted2018-07-20
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Date published2018-10-24
Moisture content of natural gas in bottom hole zone
- Authors:
- E. A. Bondarev
- I. I. Rozhin
- K. K. Argunova
For the traditional problem of gas flow to a well in the center of circular reservoir, the influence of initial reservoir conditions on dynamics of gas moisture content distribution has been determined. Investigations have been performed in the framework of mathematical model of non-isothermal real gas flow through porous media where heat conductivity was considered to be negligible in comparison with convective heat transfer. It is closed by empirical correlation of compressibility coefficient with pressure and temperature, checked in previous publications. Functional dependence of moisture content in gas on pressure and temperature is based on empirical modification of Bukacek relation. Numerical experiment was performed in the following way. At first step, axisymmetric problem of non-isothermal flow of real gas in porous media was solved for a given value of pressure at the borehole bottom, which gives the values of pressure and temperature as functions of time and radial coordinate. Conditions at the outer boundary of the reservoir correspond to water drive regime of gas production. At the second step, the calculated functions of time and coordinate were used to find the analogous function for moisture content. The results of experiment show that if reservoir temperature essentially exceeds gas – hydrate equilibrium temperature than moisture content in gas distribution is practically reflects the one of gas temperature. In the opposite case, gas will contain water vapor only near bottom hole and at the rest of reservoir it will be almost zero. In both cases, pressure manifests its role through the rate of gas production, which in turn influences convective heat transfer and gas cooling due to throttle effect.
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Date submitted2009-08-23
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Date accepted2009-10-17
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Date published2010-02-01
Reseach of cutoff grade influence on economic performances of mining
- Authors:
- M. D. Morozov
Research of cutoff grade influence on economic performances of mine as well as parameters and configuration of ore deposits with the help of the advanced geoinformation system were carried out. Computer modeling of an ore chute was made; the results of calculation were presented, involvement is given.
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Date submitted2009-08-13
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Date accepted2009-10-29
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Date published2010-02-01
Analysis of statistical data of lecture of the alloyed steels
- Authors:
- R. V. Kurtenkov
Influence of a chemical compound on the carbon contents in a steel is analysed, in the course of processing of month basic data the mathematical model is received, it is offered optimum significances of source parametres at the carbon contents in a steel.
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Date submitted2008-11-25
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Date accepted2009-01-17
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Date published2009-12-11
The basis of minimal industrial maintenance of useful component for deposits of complex mineral raw material
- Authors:
- V. V. Ternovoy
- A. I. Samoilenko
- O. I. Tsarakov
The problems of the calculation of the minimal industrial maintenance for complex ores of nonferrous metals are considered. Then the calculation of the minimal industrial maintenance of nickel according to different formulas for the technical-economic basis of exploratory conditions of concrete ore deposits and the analysis of results were carried out.