Pub Date : 2024-07-04DOI: 10.21285/1814-3520-2024-2-371-385
A. A. Ilin, I. A. Pikalova, N. N. Zobnin
We study the distribution of boron between silicon and slag of the CaO-SiO2, MgO-SiO2, CaO-MgO-SiO2, and CaO-Al2O3-SiO2 systems under reducing conditions with the purpose of determining the feasibility of using boroncontaining materials to eliminate slagging in the melting zone during industrial silicon smelting in ore smelting furnaces. To that end, we used model slags obtained by melting chemically pure oxides, as well as silicon-based alloys with an admixture of boron. High-purity 5N silicon produced by Kazakhstan Solar Silicon LLP was used. Boron alloys were manufactured independently by melting silicon with boron. The experiments included holding liquid slag and alloys in graphite crucibles at a temperature of 1600°C under poorly reducing conditions. The boron content in slag and silicon samples was analyzed by inductively coupled plasma mass spectrometry. The boron distribution coefficient in the above systems was established to range from 2 to 2.5 for the entire melt area of these systems at 1600°C. The boron distribution coefficient was demonstrated to decrease under an increase in the content of Al2O3 in the CaO-Al2O3-SiO2 triplet system, which agrees with the data obtained by other authors. The use of graphite crucibles in experiments creates reducing conditions, similar to those in the hearth of an ore smelting furnace. Therefore, this approach provides more adequate data in predicting the equilibrium boron content in silicon in comparison with the experiments conducted using alumina crucibles by other authors. It was also found that the boron distribution coefficient does not depend on the magnesium oxide content in double (MgO-SiO2) and triplet (CaO-MgO-SiO2) systems. In conclusion, our results lift restrictions on the content of boron in boron-containing fluxes during industrial silicon smelting.
{"title":"Study of boron distribution between silicon and slags of CaO-SiO2, MgO-SiO2, CaO-MgO-SiO2, and CaO-Al2O3-SiO2 systems under reducing conditions","authors":"A. A. Ilin, I. A. Pikalova, N. N. Zobnin","doi":"10.21285/1814-3520-2024-2-371-385","DOIUrl":"https://doi.org/10.21285/1814-3520-2024-2-371-385","url":null,"abstract":"We study the distribution of boron between silicon and slag of the CaO-SiO2, MgO-SiO2, CaO-MgO-SiO2, and CaO-Al2O3-SiO2 systems under reducing conditions with the purpose of determining the feasibility of using boroncontaining materials to eliminate slagging in the melting zone during industrial silicon smelting in ore smelting furnaces. To that end, we used model slags obtained by melting chemically pure oxides, as well as silicon-based alloys with an admixture of boron. High-purity 5N silicon produced by Kazakhstan Solar Silicon LLP was used. Boron alloys were manufactured independently by melting silicon with boron. The experiments included holding liquid slag and alloys in graphite crucibles at a temperature of 1600°C under poorly reducing conditions. The boron content in slag and silicon samples was analyzed by inductively coupled plasma mass spectrometry. The boron distribution coefficient in the above systems was established to range from 2 to 2.5 for the entire melt area of these systems at 1600°C. The boron distribution coefficient was demonstrated to decrease under an increase in the content of Al2O3 in the CaO-Al2O3-SiO2 triplet system, which agrees with the data obtained by other authors. The use of graphite crucibles in experiments creates reducing conditions, similar to those in the hearth of an ore smelting furnace. Therefore, this approach provides more adequate data in predicting the equilibrium boron content in silicon in comparison with the experiments conducted using alumina crucibles by other authors. It was also found that the boron distribution coefficient does not depend on the magnesium oxide content in double (MgO-SiO2) and triplet (CaO-MgO-SiO2) systems. In conclusion, our results lift restrictions on the content of boron in boron-containing fluxes during industrial silicon smelting.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":" 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141677810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.21285/1814-3520-2024-2-290-302
I. Donskoy
We determine the kinetic patterns of melting in a heat-generating cylindrical element under invariable supercritical conditions using numerical modelling. The study focuses on the melting process in a homogeneous sample that generates heat either through a chemical reaction or electromagnetic heating. The thermophysical properties of the sample were assumed to be constant in both solid and liquid phases. The main tool used in the study was a numerical model based on the nonstationary Stefan problem in a heat-generating body, which incorporates the descriptions of heat conduction and melting processes. The phase transition was described in terms of enthalpy. In order to select the parameters of the numerical model (grid steps), the accuracy of the difference scheme was investigated. The study presents calculated dependencies of the main melting characteristics (melting time and the maximum sample temperature at melting) on control parameters (heat generation intensity, the heat effect of melting and the ratio of thermal conductivity coefficients of the phases). By using specified approximations (temperature averaging and quasi-stationary distribution), formulas were derived to estimate the melting time of the sample. The calculations showed that the variations in the thermal properties of the sample (thermal conductivity coefficients and heat effect) significantly influence the melting rate. It was demonstrated that although the relationship between the melting time and the intensity of heat generation and the thermal effect of the phase transition is consistent with the approximate models, there is a significant quantitative difference between them, in particular, for small deviations from the critical heat generation intensity. The calculations can be used to assess the thermomechanical stability of materials with internal heat generation. The developed numerical model allows melting processes to be investigated under a wide range of conditions, including varying boundary conditions.
{"title":"Stefan problem for a heat-generating cylindrical sample with boundary conditions of the third kind: calculation of melting time","authors":"I. Donskoy","doi":"10.21285/1814-3520-2024-2-290-302","DOIUrl":"https://doi.org/10.21285/1814-3520-2024-2-290-302","url":null,"abstract":"We determine the kinetic patterns of melting in a heat-generating cylindrical element under invariable supercritical conditions using numerical modelling. The study focuses on the melting process in a homogeneous sample that generates heat either through a chemical reaction or electromagnetic heating. The thermophysical properties of the sample were assumed to be constant in both solid and liquid phases. The main tool used in the study was a numerical model based on the nonstationary Stefan problem in a heat-generating body, which incorporates the descriptions of heat conduction and melting processes. The phase transition was described in terms of enthalpy. In order to select the parameters of the numerical model (grid steps), the accuracy of the difference scheme was investigated. The study presents calculated dependencies of the main melting characteristics (melting time and the maximum sample temperature at melting) on control parameters (heat generation intensity, the heat effect of melting and the ratio of thermal conductivity coefficients of the phases). By using specified approximations (temperature averaging and quasi-stationary distribution), formulas were derived to estimate the melting time of the sample. The calculations showed that the variations in the thermal properties of the sample (thermal conductivity coefficients and heat effect) significantly influence the melting rate. It was demonstrated that although the relationship between the melting time and the intensity of heat generation and the thermal effect of the phase transition is consistent with the approximate models, there is a significant quantitative difference between them, in particular, for small deviations from the critical heat generation intensity. The calculations can be used to assess the thermomechanical stability of materials with internal heat generation. The developed numerical model allows melting processes to be investigated under a wide range of conditions, including varying boundary conditions.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":" 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141678289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.21285/1814-3520-2024-2-247-260
O. N. Voitov, I. I. Golub, L. V. Semenova, E. V. Karpova, A. L. Buchinsky
We address the problem of improving the calculation accuracy of power flow in a medium-voltage distribution network based on the measurements of smart meters installed on the secondary side of 6(10)/0.4 kV transformers. In order to account for the effect of unbalanced loads in the low-voltage network on power flow in the medium-voltage network, three-phase three-wire lines were reduced to a single-line option. This enabled the use of symmetric mode calculation programs for the asymmetric mode. The loads in the medium-voltage network were determined by adding power losses in transformer windings and core to the loads measured on the secondary side of transformers. The calculation of winding power losses using the methods of phase coordinates and symmetrical components involves determination of currents in the windings of each phase according to 48 sections of load capacity and voltage module measurements, performed by the smart meter during the day. The correctness of expressions for calculating power losses in transformer windings is confirmed by the equality of total losses in phase coordinates and symmetrical components. The negative sequence power losses in transformer windings were found to be close to zero, while zero sequence losses are significantly lower than the positive sequence losses for almost all transformers with a double star-zero winding connection scheme, regardless of the load factor and rated power. The conducted studies confirmed the possibility and effectiveness of using smart meter measurements for determining loads and calculating power flow in the medium-voltage network. This conclusion was illustrated using an actual distribution network with 26 transformers. Future research should aim to clarify the mathematical models of transformers in the joint calculation of medium- and low-voltage distribution networks.
{"title":"Effects of unbalanced loads in a low-voltage network on flow distribution in a medium-voltage network","authors":"O. N. Voitov, I. I. Golub, L. V. Semenova, E. V. Karpova, A. L. Buchinsky","doi":"10.21285/1814-3520-2024-2-247-260","DOIUrl":"https://doi.org/10.21285/1814-3520-2024-2-247-260","url":null,"abstract":"We address the problem of improving the calculation accuracy of power flow in a medium-voltage distribution network based on the measurements of smart meters installed on the secondary side of 6(10)/0.4 kV transformers. In order to account for the effect of unbalanced loads in the low-voltage network on power flow in the medium-voltage network, three-phase three-wire lines were reduced to a single-line option. This enabled the use of symmetric mode calculation programs for the asymmetric mode. The loads in the medium-voltage network were determined by adding power losses in transformer windings and core to the loads measured on the secondary side of transformers. The calculation of winding power losses using the methods of phase coordinates and symmetrical components involves determination of currents in the windings of each phase according to 48 sections of load capacity and voltage module measurements, performed by the smart meter during the day. The correctness of expressions for calculating power losses in transformer windings is confirmed by the equality of total losses in phase coordinates and symmetrical components. The negative sequence power losses in transformer windings were found to be close to zero, while zero sequence losses are significantly lower than the positive sequence losses for almost all transformers with a double star-zero winding connection scheme, regardless of the load factor and rated power. The conducted studies confirmed the possibility and effectiveness of using smart meter measurements for determining loads and calculating power flow in the medium-voltage network. This conclusion was illustrated using an actual distribution network with 26 transformers. Future research should aim to clarify the mathematical models of transformers in the joint calculation of medium- and low-voltage distribution networks.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":" 24","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141679440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.21285/1814-3520-2024-2-273-289
Yu. E. Dobrynina, D. S. Krupenev
The study aims to analyze the unit commitment models and mechanisms that are used in the wholesale electricity and capacity market in Russia and other countries, as well as to consider the methods and criteria for taking into account the system security constraints in these models. The subject matter of the study includes energy systems: wholesale energy and capacity markets in Russia, the United Kingdom, EU countries, Australia, and the United States of America. In this work, various scientific information sources were collected and analytically reviewed. The study considers the performance framework of the wholesale electricity and capacity market in different countries and the main control mechanisms in solving the unit commitment problem, as well as studying and analyzing the legal and regulatory framework in solving optimization problems. It is shown that within the domestic model, the Russian Power System Operator conducts unit commitment according to the submitted price bids, taking into account the needs of the market and the energy system balance. The considered and analyzed unit commitment scheme adopted in the Russian electric power industry fails to take full account of system security, which prompts further study of this issue. The performed comparative analysis of principles underlying the performance of models and the specifics of solving unit commitment problems revealed the strengths and weaknesses in the approaches adopted in different countries both in terms of the legislation and models. The conducted analytical study helped to formulate the key points for each model that can be used to solve the unit commitment problem.
{"title":"Consideration of system security criteria in the models of power system unit commitment","authors":"Yu. E. Dobrynina, D. S. Krupenev","doi":"10.21285/1814-3520-2024-2-273-289","DOIUrl":"https://doi.org/10.21285/1814-3520-2024-2-273-289","url":null,"abstract":"The study aims to analyze the unit commitment models and mechanisms that are used in the wholesale electricity and capacity market in Russia and other countries, as well as to consider the methods and criteria for taking into account the system security constraints in these models. The subject matter of the study includes energy systems: wholesale energy and capacity markets in Russia, the United Kingdom, EU countries, Australia, and the United States of America. In this work, various scientific information sources were collected and analytically reviewed. The study considers the performance framework of the wholesale electricity and capacity market in different countries and the main control mechanisms in solving the unit commitment problem, as well as studying and analyzing the legal and regulatory framework in solving optimization problems. It is shown that within the domestic model, the Russian Power System Operator conducts unit commitment according to the submitted price bids, taking into account the needs of the market and the energy system balance. The considered and analyzed unit commitment scheme adopted in the Russian electric power industry fails to take full account of system security, which prompts further study of this issue. The performed comparative analysis of principles underlying the performance of models and the specifics of solving unit commitment problems revealed the strengths and weaknesses in the approaches adopted in different countries both in terms of the legislation and models. The conducted analytical study helped to formulate the key points for each model that can be used to solve the unit commitment problem.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":" 41","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141679076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.21285/1814-3520-2024-2-224-237
V. Svinin, A. Shutenkov, B. B. Ponomarev
The aim is to develop and substantiate a complex of technical and economic requirements for the design of a self-feed drilling machine produced in the Russian Federation, which is particularly relevant in the context of import substitution. The study considers self-feed drilling machines produced by Atlas Copco, Desoutter and Recoules as references to match their performance and specifications. By analogy with these machines, the limiting weight and overall dimensions of the developed machine should be up to 6 kg and 320x110x450 mm, respectively. The selection of motors for spindle rotation and axial feed is carried out by drilling a hole with a diameter of 12 mm in a mixed 58 mm thick stack using a carbide drill. This stack includes steel sheets (30KhGSA grade), polymer composite materials (carbon fibre-based), titanium alloy (Vt6 grade) and aluminium alloy (1933 grade). The required power for the electric drives was determined using cutting conditions specified in reference manuals and by drilling tests of a mixed stack carried out using a DMC 635 V machine equipped with a Kistler 9123CQ05 plate dynamometer. Oscillograms of axial force and torque showed that the highest resistance occurs when drilling the titanium alloy. The following specifications were calculated and confirmed for the projected self-feed drilling machine: the required power for the electric drives is 1.5 kW for the feed drive and 2.8 kW for the spindle rotation drive. The maximum required rotation speed is 1940 rpm, and the maximum required feed rate is 4.5 mm/rev. In order to grind chips and suppress potential auto-oscillations of the drill, it is recommended that the modulations of the feed and spindle rotation speeds created by a computer numerical control system be used. Future research will involve the production and testing of a prototype self-feed drilling machine, designed in accordance with the provided recommendations.
{"title":"Main technical parameters for designing a new self-feed drilling machine","authors":"V. Svinin, A. Shutenkov, B. B. Ponomarev","doi":"10.21285/1814-3520-2024-2-224-237","DOIUrl":"https://doi.org/10.21285/1814-3520-2024-2-224-237","url":null,"abstract":"The aim is to develop and substantiate a complex of technical and economic requirements for the design of a self-feed drilling machine produced in the Russian Federation, which is particularly relevant in the context of import substitution. The study considers self-feed drilling machines produced by Atlas Copco, Desoutter and Recoules as references to match their performance and specifications. By analogy with these machines, the limiting weight and overall dimensions of the developed machine should be up to 6 kg and 320x110x450 mm, respectively. The selection of motors for spindle rotation and axial feed is carried out by drilling a hole with a diameter of 12 mm in a mixed 58 mm thick stack using a carbide drill. This stack includes steel sheets (30KhGSA grade), polymer composite materials (carbon fibre-based), titanium alloy (Vt6 grade) and aluminium alloy (1933 grade). The required power for the electric drives was determined using cutting conditions specified in reference manuals and by drilling tests of a mixed stack carried out using a DMC 635 V machine equipped with a Kistler 9123CQ05 plate dynamometer. Oscillograms of axial force and torque showed that the highest resistance occurs when drilling the titanium alloy. The following specifications were calculated and confirmed for the projected self-feed drilling machine: the required power for the electric drives is 1.5 kW for the feed drive and 2.8 kW for the spindle rotation drive. The maximum required rotation speed is 1940 rpm, and the maximum required feed rate is 4.5 mm/rev. In order to grind chips and suppress potential auto-oscillations of the drill, it is recommended that the modulations of the feed and spindle rotation speeds created by a computer numerical control system be used. Future research will involve the production and testing of a prototype self-feed drilling machine, designed in accordance with the provided recommendations.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":" 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141678278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-10DOI: 10.21285/1814-3520-2023-4-727-736
Ya. I. Krupeneva, E. Boloev, I. I. Golub
The goal is to determine methods for calculating power losses in a three-phase four-wire low voltage distribution network using measurements of a balance smart meter and consumer smart meters, and to establish the factors influencing the power losses and their allocation among individual network wires, loads, and consumers. The study involved examining three methods for determining power losses for current measurement snapshot. The first method suggests calculating losses as the difference between the power supplied to the network and the total power consumed. The second method calculates power losses using the contribution method. The third method, which in addition to measurement information requires knowledge of the topology and parameters of the network components, determines power losses based on the results of the state estimation method. The research proposes an algorithm for transition from a four-wire distribution network modeling to a three-wire one. The algorithm allocates power losses of the neutral wire among the phase wires. The findings indicate that the negative losses in the network with unbalanced phase loads are caused by the presence at the nodes of the least loaded phase of higher voltage than the voltage at the power supply node. The reason for higher losses in phases with minimal load is the uneven allocation of loads in the phases. In addition, the study reveals that the power loss values obtained by the contribution method, i.e. directly from the measurements of smart meters, are closer to the losses determined from the readings of the balance meter and consumer meters, compared to the losses found from the state estimation results. The considered methods for calculation and allocation of power losses are illustrated by an example of a real-world distribution network equipped with smart meters. The paper demonstrates the examples of allocating total power losses between phase wires and a neutral wire, among phase wires only, and between total loads at phase nodes and individual consumers in phases.
{"title":"Allocation of power losses and energy in the distribution network","authors":"Ya. I. Krupeneva, E. Boloev, I. I. Golub","doi":"10.21285/1814-3520-2023-4-727-736","DOIUrl":"https://doi.org/10.21285/1814-3520-2023-4-727-736","url":null,"abstract":"The goal is to determine methods for calculating power losses in a three-phase four-wire low voltage distribution network using measurements of a balance smart meter and consumer smart meters, and to establish the factors influencing the power losses and their allocation among individual network wires, loads, and consumers. The study involved examining three methods for determining power losses for current measurement snapshot. The first method suggests calculating losses as the difference between the power supplied to the network and the total power consumed. The second method calculates power losses using the contribution method. The third method, which in addition to measurement information requires knowledge of the topology and parameters of the network components, determines power losses based on the results of the state estimation method. The research proposes an algorithm for transition from a four-wire distribution network modeling to a three-wire one. The algorithm allocates power losses of the neutral wire among the phase wires. The findings indicate that the negative losses in the network with unbalanced phase loads are caused by the presence at the nodes of the least loaded phase of higher voltage than the voltage at the power supply node. The reason for higher losses in phases with minimal load is the uneven allocation of loads in the phases. In addition, the study reveals that the power loss values obtained by the contribution method, i.e. directly from the measurements of smart meters, are closer to the losses determined from the readings of the balance meter and consumer meters, compared to the losses found from the state estimation results. The considered methods for calculation and allocation of power losses are illustrated by an example of a real-world distribution network equipped with smart meters. The paper demonstrates the examples of allocating total power losses between phase wires and a neutral wire, among phase wires only, and between total loads at phase nodes and individual consumers in phases.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":"5 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139534714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-10DOI: 10.21285/1814-3520-2023-4-809-820
G. V. Petrov, D. V. Gordeev, V. R. Bekirova
The study aims to investigate the most efficient method for significant minimization of the impact of organic carbon on gold recovery from double refractory raw materials. We tested three double refractory gold-sulfide concentrates from different deposits with the content of gold from 23.5 to 40.9 g/t and total carbon from 1.2 to 9.5 wt %. Thermal treatment was carried out in a tubular rotary furnace that provided permanent temperature setting and rotation speed in the reactor. The initial concentrate was grinded as pulp in a Fritsch planetary mono mill Pulverisette 6. Autoclave oxidation was performed in Premex and Büchi titanium autoclaves. The technology of autoclave oxidation with the addition of a secondary oxidizer was found to be the most efficient, since it can increase gold recovery up to 97%. Another technology – hightemperature autoclave oxidation – also proved high performance; however, a significant increase in the residence time of the material in the autoclave (up to 120 min) at elevated temperatures is required to achieve this performance. According to the results, thermal treatment in general can provide a small increase in gold recovery (up to 4%). Due to this, it can be used as an additional processing with other methods analyzed in this article rather than as a self-sufficient technological solution. The studies revealed that the preliminary thermal treatment of concentrates entering autoclave oxidation shows a positive effect; high-temperature autoclave oxidation of concentrates with different carbon content provides high gold recovery for high-carbon concentrates; the use of a secondary oxidizer (in the form of nitric acid) also benefits the gold recovery. The high efficiency of the technology for concentrates with different carbon content allows us to recommend it for further research.
{"title":"Comparison of methods for enhancing gold recovery from double refractory concentrates using the technology of autoclave oxidation","authors":"G. V. Petrov, D. V. Gordeev, V. R. Bekirova","doi":"10.21285/1814-3520-2023-4-809-820","DOIUrl":"https://doi.org/10.21285/1814-3520-2023-4-809-820","url":null,"abstract":"The study aims to investigate the most efficient method for significant minimization of the impact of organic carbon on gold recovery from double refractory raw materials. We tested three double refractory gold-sulfide concentrates from different deposits with the content of gold from 23.5 to 40.9 g/t and total carbon from 1.2 to 9.5 wt %. Thermal treatment was carried out in a tubular rotary furnace that provided permanent temperature setting and rotation speed in the reactor. The initial concentrate was grinded as pulp in a Fritsch planetary mono mill Pulverisette 6. Autoclave oxidation was performed in Premex and Büchi titanium autoclaves. The technology of autoclave oxidation with the addition of a secondary oxidizer was found to be the most efficient, since it can increase gold recovery up to 97%. Another technology – hightemperature autoclave oxidation – also proved high performance; however, a significant increase in the residence time of the material in the autoclave (up to 120 min) at elevated temperatures is required to achieve this performance. According to the results, thermal treatment in general can provide a small increase in gold recovery (up to 4%). Due to this, it can be used as an additional processing with other methods analyzed in this article rather than as a self-sufficient technological solution. The studies revealed that the preliminary thermal treatment of concentrates entering autoclave oxidation shows a positive effect; high-temperature autoclave oxidation of concentrates with different carbon content provides high gold recovery for high-carbon concentrates; the use of a secondary oxidizer (in the form of nitric acid) also benefits the gold recovery. The high efficiency of the technology for concentrates with different carbon content allows us to recommend it for further research.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":"55 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139534954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-10DOI: 10.21285/1814-3520-2023-4-737-748
S. Mitrofanov, D. K. Baykasenov
The paper evaluates the generation of electrical energy by a solar power plant equipped with a solar tracking system using the ASHRAE clear-sky method for calculating solar insolation. The mathematical algorithm uses the MathCad system with data export and analysis in Microsoft Excel. Collected over a month and the operation period in 2022–2023, data on electricity generation by solar stations characterised by an optimal constant angle of inclination of the solar panel and equipped with a solar tracking system were used. By taking into account the varying ambient temperature, dust content, and solar transmission by the solar panel coating, the given algorithm allowed electricity generation by a solar panel to be forecasted with an average absolute error ranging from 0.22 to 9.8. To determine solar insolation for a specific day and the geographical coordinates of the intended construction site of a solar power plant, a mathematical model was developed using MathCad software. The experimental and computational studies carried out on selected clear days, accounting for varying weather conditions, demonstrated the adequacy of this method and its applicability for forecasting electricity generation with different inclination angles of a solar panel. It was established that a solar power plant with a solar tracking system generated 37% more electricity per year than that with fixed solar panels. The ASHRAE Clear-Sky method for calculating solar insolation allows the amount of electricity generated for a specific region to be estimated with minimal input data. Further research will focus on defining and improving methods for forecasting electricity generation by a solar power plant on overcast days.
{"title":"Operation of a solar power plant with dual-axis solar tracker","authors":"S. Mitrofanov, D. K. Baykasenov","doi":"10.21285/1814-3520-2023-4-737-748","DOIUrl":"https://doi.org/10.21285/1814-3520-2023-4-737-748","url":null,"abstract":"The paper evaluates the generation of electrical energy by a solar power plant equipped with a solar tracking system using the ASHRAE clear-sky method for calculating solar insolation. The mathematical algorithm uses the MathCad system with data export and analysis in Microsoft Excel. Collected over a month and the operation period in 2022–2023, data on electricity generation by solar stations characterised by an optimal constant angle of inclination of the solar panel and equipped with a solar tracking system were used. By taking into account the varying ambient temperature, dust content, and solar transmission by the solar panel coating, the given algorithm allowed electricity generation by a solar panel to be forecasted with an average absolute error ranging from 0.22 to 9.8. To determine solar insolation for a specific day and the geographical coordinates of the intended construction site of a solar power plant, a mathematical model was developed using MathCad software. The experimental and computational studies carried out on selected clear days, accounting for varying weather conditions, demonstrated the adequacy of this method and its applicability for forecasting electricity generation with different inclination angles of a solar panel. It was established that a solar power plant with a solar tracking system generated 37% more electricity per year than that with fixed solar panels. The ASHRAE Clear-Sky method for calculating solar insolation allows the amount of electricity generated for a specific region to be estimated with minimal input data. Further research will focus on defining and improving methods for forecasting electricity generation by a solar power plant on overcast days.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":" 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139627510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-10DOI: 10.21285/1814-3520-2023-4-682-693
P. A. Polyakov
The aim is to develop a method for ensuring the stability and efficiency of the braking process by differentiating the friction linings of brake pads of pad-type disc braking mechanisms. The research applied differentiation of the interaction time of friction pairs and their area, which provides the highest stability indicators of braking mechanisms. The non-standardized bench equipment developed by the author, as well as segmental braking mechanisms providing differentiation of friction pairs by area were used in the study. A method of designing the resultant braking torque was developed using the relationship between the transverse movement of the pads and the developed braking torque of the friction unit. As a result of bench tests, the stability and fluctuation coefficients of the braking torque of the developed pad-type disc brake mechanisms with six pressing elements increased by 12.2 and 34.9%. These values were obtained as compared to serial brake mechanisms equipped with a monopressing mechanism with a single brake pad. The discrepancies between the simulated and obtained data during the bench test on the stability criteria averaged 5.1 and 6.7% for the stability coefficients and braking torque fluctuations for the three brake mechanism variants under consideration, respectively. Differentiation of pressing elements and segmentation of brake pads has the effect of increasing the stability criteria and braking efficiency for pad-type disc brakes. With the analysis of the dependence of the transverse displacement and the developed braking torque, a guaranteed result on the stability criterion and braking torque fluctuations of pad-type disc brakes was modeled. Based on the conducted bench tests, the model developed for obtaining the resultant braking torque for the braking mechanism with segmental pads can be used for designing friction pairs with the set parameters.
{"title":"Developing the method ensuring stable braking via advanced design of braking devices","authors":"P. A. Polyakov","doi":"10.21285/1814-3520-2023-4-682-693","DOIUrl":"https://doi.org/10.21285/1814-3520-2023-4-682-693","url":null,"abstract":"The aim is to develop a method for ensuring the stability and efficiency of the braking process by differentiating the friction linings of brake pads of pad-type disc braking mechanisms. The research applied differentiation of the interaction time of friction pairs and their area, which provides the highest stability indicators of braking mechanisms. The non-standardized bench equipment developed by the author, as well as segmental braking mechanisms providing differentiation of friction pairs by area were used in the study. A method of designing the resultant braking torque was developed using the relationship between the transverse movement of the pads and the developed braking torque of the friction unit. As a result of bench tests, the stability and fluctuation coefficients of the braking torque of the developed pad-type disc brake mechanisms with six pressing elements increased by 12.2 and 34.9%. These values were obtained as compared to serial brake mechanisms equipped with a monopressing mechanism with a single brake pad. The discrepancies between the simulated and obtained data during the bench test on the stability criteria averaged 5.1 and 6.7% for the stability coefficients and braking torque fluctuations for the three brake mechanism variants under consideration, respectively. Differentiation of pressing elements and segmentation of brake pads has the effect of increasing the stability criteria and braking efficiency for pad-type disc brakes. With the analysis of the dependence of the transverse displacement and the developed braking torque, a guaranteed result on the stability criterion and braking torque fluctuations of pad-type disc brakes was modeled. Based on the conducted bench tests, the model developed for obtaining the resultant braking torque for the braking mechanism with segmental pads can be used for designing friction pairs with the set parameters.","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":" 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139627444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-10DOI: 10.21285/1814-3520-2023-4-749-759
N. L. Mikhalchuk
The article focuses on the development of an effective design and algorithms for automatic control of singlephase DC electric locomotives according to the laws of constant traction force and power without switching electrical devices within power electric circuits. Methods of mathematical modelling for electromagnetic, electromechanical, and mechanical processes by MatLab, Simulink, and SimPowerSystems software were used to address this problem. The nonlinearities of the magnetisation curve were taken into account, along with the influence of eddy currents from the coils of the main and additional poles in traction motors. Structural and parametric synthesis of a power electrical circuit and control algorithms by controlled bridge IGBT converters were used in the simulation. The object of the research was an electrotechnical complex, including a 9840 kW three-stack electric locomotive 3ES5K “Ermak”. On the basis of the research results, it is recommended to use a power electrical circuit with two reversible converters for each of the three sections on the electric locomotive. These converters provide power to four 820 kW traction motors and a group power supply for controlled bridge IGBT converters shunting the field coils for axial traction control. The calculations confirmed the applicability of a scheme for individual control of traction electric motors and excitation currents, ensuring a smooth increase in the traction force of an electric locomotive. The developed algorithm of axial traction control ensures a smooth increase in this force and creates the optimal conditions for coupling the wheels of an electric locomotive with rails. These solutions can be used in the manufacture and modernisation of new and existing electric locomotives
{"title":"Selection of power supply scheme for controlled excitation converters in traction electric motors of single-phase DC electric locomotives","authors":"N. L. Mikhalchuk","doi":"10.21285/1814-3520-2023-4-749-759","DOIUrl":"https://doi.org/10.21285/1814-3520-2023-4-749-759","url":null,"abstract":"The article focuses on the development of an effective design and algorithms for automatic control of singlephase DC electric locomotives according to the laws of constant traction force and power without switching electrical devices within power electric circuits. Methods of mathematical modelling for electromagnetic, electromechanical, and mechanical processes by MatLab, Simulink, and SimPowerSystems software were used to address this problem. The nonlinearities of the magnetisation curve were taken into account, along with the influence of eddy currents from the coils of the main and additional poles in traction motors. Structural and parametric synthesis of a power electrical circuit and control algorithms by controlled bridge IGBT converters were used in the simulation. The object of the research was an electrotechnical complex, including a 9840 kW three-stack electric locomotive 3ES5K “Ermak”. On the basis of the research results, it is recommended to use a power electrical circuit with two reversible converters for each of the three sections on the electric locomotive. These converters provide power to four 820 kW traction motors and a group power supply for controlled bridge IGBT converters shunting the field coils for axial traction control. The calculations confirmed the applicability of a scheme for individual control of traction electric motors and excitation currents, ensuring a smooth increase in the traction force of an electric locomotive. The developed algorithm of axial traction control ensures a smooth increase in this force and creates the optimal conditions for coupling the wheels of an electric locomotive with rails. These solutions can be used in the manufacture and modernisation of new and existing electric locomotives","PeriodicalId":488940,"journal":{"name":"iPolytech Journal","volume":" 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139627827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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