This paper deals with thermodynamic and thermokinetic properties of R404A refrigerant, which is one of the more commonly used in mine air compression refrigerators. Knowledge of these parameters is essential to analyze performance of such refrigeration equipment, to design it, or to estimate efficiency of air refrigerators using various refrigerants. These properties can be defined using 27 simple computational formulas, contained in 4 tables (Tables 2, 6, 10 and 12). The relationships determining thermodynamic and thermokinetic parameters of R404A occur in saturated liquid region, dry saturated vapor region, superheated vapor region and supercooled liquid region. The developed relationships were subjected to statistical verification. For this purpose, correlation coefficients, coefficients of determination, as well as absolute and relative deviations were determined by comparing results of the calculations with the corresponding results obtained by REFPROP 7 (Lemmon et al., 2002). Results of verification are contained in Tables 14 and 15.
本文研究了矿井空气压缩制冷机中常用的R404A制冷剂的热力学和热力学性质。了解这些参数对于分析此类制冷设备的性能、设计制冷设备或评估使用各种制冷剂的空气制冷机的效率至关重要。这些属性可以使用27个简单的计算公式来定义，这些公式包含在4个表中(表2、6、10和12)。决定R404A热力学和热力学参数的关系发生在饱和液体区、干燥饱和蒸汽区、过热蒸汽区和过冷液体区。发展的关系受到统计验证。为此，通过将计算结果与REFPROP 7得到的相应结果进行比较，确定相关系数、决定系数以及绝对和相对偏差(Lemmon et al.， 2002)。核查结果载于表14和表15。
{"title":"FUNCTIONAL DEPENDENCIES OF THERMODYNAMIC AND THERMOKINETIC PARAMETERS OF REFRIGERANTS USED IN MINE AIR REFRIGERATORS .PART 2 – REFRIGERANT R404A","authors":"B. Nowak, P. Życzkowski, R. Łuczak","doi":"10.24425/118883","DOIUrl":"https://doi.org/10.24425/118883","url":null,"abstract":"This paper deals with thermodynamic and thermokinetic properties of R404A refrigerant, which is one of the more commonly used in mine air compression refrigerators. Knowledge of these parameters is essential to analyze performance of such refrigeration equipment, to design it, or to estimate efficiency of air refrigerators using various refrigerants. These properties can be defined using 27 simple computational formulas, contained in 4 tables (Tables 2, 6, 10 and 12). The relationships determining thermodynamic and thermokinetic parameters of R404A occur in saturated liquid region, dry saturated vapor region, superheated vapor region and supercooled liquid region. The developed relationships were subjected to statistical verification. For this purpose, correlation coefficients, coefficients of determination, as well as absolute and relative deviations were determined by comparing results of the calculations with the corresponding results obtained by REFPROP 7 (Lemmon et al., 2002). Results of verification are contained in Tables 14 and 15.","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43472129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/ams.2021.136689
{"title":"Simulation of the Evacuation of People in a Road Tunnel in the Event of Fire – Case Study","authors":"","doi":"10.24425/ams.2021.136689","DOIUrl":"https://doi.org/10.24425/ams.2021.136689","url":null,"abstract":"","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43663978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/ams.2020.135184
Coal waste stockpiles – as artificial formations being a result of the exploitation of underground coal deposits – are constantly influenced by external factors, such as rock mass movements affecting the stability of the stockpile body and changing weather conditions, leading to a cycle of aerological phenomena which intensify the self-heating of the deposited material. Together with the occurrence of external factors, the stored material is also characterised by a set of internal features (also called genetic) that have a direct impact on the kinetics of the self-heating reaction. The paper focuses mainly on the issue of external factors such as the inclination angle of the stockpile, erosion of the slopes and thermal insulation of the layers of the stored material, which affect the phenomenon of self-heating of the material. Studies of impact of these factors on the thermal stability of coal waste stockpiles are important in the aspect of secondary exploitation of the stockpiles as well as during their reclamation or revitalisation. The numerical solutions presented in the paper should be treated as guidelines that define the directions of analysis for specific cases.
{"title":"Aerological Factors Favouring the Occurrence of Endogenous Fires on Coal Waste Stockpiles","authors":"","doi":"10.24425/ams.2020.135184","DOIUrl":"https://doi.org/10.24425/ams.2020.135184","url":null,"abstract":"Coal waste stockpiles – as artificial formations being a result of the exploitation of underground coal deposits – are constantly influenced by external factors, such as rock mass movements affecting the stability of the stockpile body and changing weather conditions, leading to a cycle of aerological phenomena which intensify the self-heating of the deposited material. Together with the occurrence of external factors, the stored material is also characterised by a set of internal features (also called genetic) that have a direct impact on the kinetics of the self-heating reaction. The paper focuses mainly on the issue of external factors such as the inclination angle of the stockpile, erosion of the slopes and thermal insulation of the layers of the stored material, which affect the phenomenon of self-heating of the material. Studies of impact of these factors on the thermal stability of coal waste stockpiles are important in the aspect of secondary exploitation of the stockpiles as well as during their reclamation or revitalisation. The numerical solutions presented in the paper should be treated as guidelines that define the directions of analysis for specific cases.","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44083168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/ams.2019.129375
Beifang Wang, Keming Sun, B. Liang, Weiji Sun
{"title":"Development and Application of an Experimental Device for Measuring Storage Coefficient in a Coal Mine Underground Reservoir","authors":"Beifang Wang, Keming Sun, B. Liang, Weiji Sun","doi":"10.24425/ams.2019.129375","DOIUrl":"https://doi.org/10.24425/ams.2019.129375","url":null,"abstract":"","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46739520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/AMS.2020.133194
H. Guo, M. Ji, Weisheng Zhao
Through in-situ stress measurements, stress data were obtained from an auxiliary transportation ro- adway in a coal mine in Shanxi Province, China. Based on the principles of elastic mechanics and using a generalized plane strain model, the mechanical effects of the in-situ stresses on an idealized roadway were calculated and the distributions of stresses, displacements, and plastic zones determined. Building on this model, the vulnerable zones in the roadway cross section were identified. Ground support specifica- tions were developed and during specification design, comprehensive consideration was given to factors affecting the stability of the rock surrounding the roadway. A scientific and reasonable support scheme was put forward. Practical experience in the coal mine shows the normal forces of anchor bolt and cable, the minimal convergence of roof to floor, and a generally good support in the auxiliary transportation roadway. The support should ensure safe production during its service life. This study provides a new method for designing roadway support systems that can be particularly valuable for high-stress roadways.
{"title":"Roadway Support Design Based on In-situ Stress and Its Asymmetrical Distributions in a Coal Mine","authors":"H. Guo, M. Ji, Weisheng Zhao","doi":"10.24425/AMS.2020.133194","DOIUrl":"https://doi.org/10.24425/AMS.2020.133194","url":null,"abstract":"Through in-situ stress measurements, stress data were obtained from an auxiliary transportation ro- adway in a coal mine in Shanxi Province, China. Based on the principles of elastic mechanics and using a generalized plane strain model, the mechanical effects of the in-situ stresses on an idealized roadway were calculated and the distributions of stresses, displacements, and plastic zones determined. Building on this model, the vulnerable zones in the roadway cross section were identified. Ground support specifica- tions were developed and during specification design, comprehensive consideration was given to factors affecting the stability of the rock surrounding the roadway. A scientific and reasonable support scheme was put forward. Practical experience in the coal mine shows the normal forces of anchor bolt and cable, the minimal convergence of roof to floor, and a generally good support in the auxiliary transportation roadway. The support should ensure safe production during its service life. This study provides a new method for designing roadway support systems that can be particularly valuable for high-stress roadways.","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45862464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/ams.2020.134131
T. Janoszek
The use of computer techniques at the design stage of industrial facilities is essential in modern times. The ability to shorten the time required to develop a project and assess the safety of the use of assumptions, often enables the reduction of the costs incurred in the future. The possibility to skip expensive prototype tests by using 3D prototyping is why it is currently the prevailing model in the design of industrial facilities, including in the mining industry. In the case of a longwall working, its stability requires the maintenance of the geometric continuity of floor rocks in cooperation with a powered roof support. The paper investigates the problem of longwall working stability under the influence of roof properties, coal properties, shield loading and the roof-floor interaction. The longwall working stability is represented by an index, factor of safety (FOS), and is correlated with a previously proposed roof capacity index ‘g‘. The topic of the paper does address an issue of potential interest. The assessment of the stability of the roof in longwalls was based on the numerical analysis of the factor of safety (FOS), using the Mohr-Coulomb stress criterion. The Mohr-Coulomb stress criterion enables the prediction of the occurrence of failures when the connection of the maximum tensile principal stress σ1 and the minimum compressive principal stress σ3 exceed relevant stress limits. The criterion is used for materials which indicates distinct tensile and compressive characteristics. The numerical method presented in the paper can be utilized in evaluating the mining natural hazards through predicting the parameters, which determine the roof maintenance in the longwall working. One of the purposes of the numerical analysis was to draw attention to the possibilities that are currently created by specialized software as an important element accompanying the modern design process, which forms part of intelligent underground mining 4.0.
{"title":"The Assessment of Longwall Working Stability Based on the Mohr-Coulomb Stress Criterion – Numerical Analysis","authors":"T. Janoszek","doi":"10.24425/ams.2020.134131","DOIUrl":"https://doi.org/10.24425/ams.2020.134131","url":null,"abstract":"The use of computer techniques at the design stage of industrial facilities is essential in modern times. The ability to shorten the time required to develop a project and assess the safety of the use of assumptions, often enables the reduction of the costs incurred in the future. The possibility to skip expensive prototype tests by using 3D prototyping is why it is currently the prevailing model in the design of industrial facilities, including in the mining industry. In the case of a longwall working, its stability requires the maintenance of the geometric continuity of floor rocks in cooperation with a powered roof support. The paper investigates the problem of longwall working stability under the influence of roof properties, coal properties, shield loading and the roof-floor interaction. The longwall working stability is represented by an index, factor of safety (FOS), and is correlated with a previously proposed roof capacity index ‘g‘. The topic of the paper does address an issue of potential interest. The assessment of the stability of the roof in longwalls was based on the numerical analysis of the factor of safety (FOS), using the Mohr-Coulomb stress criterion. The Mohr-Coulomb stress criterion enables the prediction of the occurrence of failures when the connection of the maximum tensile principal stress σ1 and the minimum compressive principal stress σ3 exceed relevant stress limits. The criterion is used for materials which indicates distinct tensile and compressive characteristics. The numerical method presented in the paper can be utilized in evaluating the mining natural hazards through predicting the parameters, which determine the roof maintenance in the longwall working. One of the purposes of the numerical analysis was to draw attention to the possibilities that are currently created by specialized software as an important element accompanying the modern design process, which forms part of intelligent underground mining 4.0.","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47967281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/ams.2019.131069
Bing-xiang Huang, Xinglong Zhao, T. Sun
Influenced by the dynamic pressure of the front abutment pressure and the lateral abutment pressure, large deformation of surrounding rock occurs advancing working face in the entry heading adjacent to the active longwall mining face. Based on the cause analysis of entry large deformation, a new technology was put forward to solve the problem, and the designing method of drilling hole parameters for directional hydraulic fracturing was formed. Holes are drilled in the entry or in the high drainage entry to a certain rock layer over the adjacent working face, hydraulic cutting or slotting at the bottom of a borehole were also applied in advance to guide the hydraulic fractures extend in expected direction, through which the hard roof above the coal pillar can be cut off directionally. As a result, the stress concentration around the entry was transferred, and the entry was located in a destressing area. The field test at Majialiang coal mine indicates that the propagation length of cracks in single borehole is more than 15 m. After hydraulic fracturing, the large deformation range of the entry is reduced by 45 m, the average floor heave is reduced by 70%, and the average convergence of the entry’s two sides is reduced by 65%. Directional hydraulic fracturing has a better performance to control the large deformation of the dynamic pressure of the entry heading adjacent to the advancing coal face. Besides, it can improve the performance of the safety production.
{"title":"Field Experiment of Destress Hydraulic Fracturing for Controlling the Large Deformation of the Dynamic Pressure Entry Heading Adjacent to the Advancing Longwall Face","authors":"Bing-xiang Huang, Xinglong Zhao, T. Sun","doi":"10.24425/ams.2019.131069","DOIUrl":"https://doi.org/10.24425/ams.2019.131069","url":null,"abstract":"Influenced by the dynamic pressure of the front abutment pressure and the lateral abutment pressure, large deformation of surrounding rock occurs advancing working face in the entry heading adjacent to the active longwall mining face. Based on the cause analysis of entry large deformation, a new technology was put forward to solve the problem, and the designing method of drilling hole parameters for directional hydraulic fracturing was formed. Holes are drilled in the entry or in the high drainage entry to a certain rock layer over the adjacent working face, hydraulic cutting or slotting at the bottom of a borehole were also applied in advance to guide the hydraulic fractures extend in expected direction, through which the hard roof above the coal pillar can be cut off directionally. As a result, the stress concentration around the entry was transferred, and the entry was located in a destressing area. The field test at Majialiang coal mine indicates that the propagation length of cracks in single borehole is more than 15 m. After hydraulic fracturing, the large deformation range of the entry is reduced by 45 m, the average floor heave is reduced by 70%, and the average convergence of the entry’s two sides is reduced by 65%. Directional hydraulic fracturing has a better performance to control the large deformation of the dynamic pressure of the entry heading adjacent to the advancing coal face. Besides, it can improve the performance of the safety production.","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44067953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/AMS.2019.129364
Robert Czarnota, E. Knapik, P. Wojnarowski, Damian Janiga, J. Stopa
{"title":"Carbon Dioxide Separation Technologies","authors":"Robert Czarnota, E. Knapik, P. Wojnarowski, Damian Janiga, J. Stopa","doi":"10.24425/AMS.2019.129364","DOIUrl":"https://doi.org/10.24425/AMS.2019.129364","url":null,"abstract":"","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49307204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/ams.2022.142409
Shafi Muhammad Pathan, A. Pathan, F. I. Siddiqui, M. Memon, Mairaj Hyder Alias Aamir Soomro
Slope Stability Analysis is one of the main aspects of open-pit mine planning because the calculations regarding the stability of slopes are necessary to assess the stability of the open pit slopes together with the financial feasibility of the mining operations. this study was conducted to analyse the effect of groundwater on the shear strength properties of soft rock formations and determine the optimum overall slope angle for an open pit coal mine at thar Coalfield, Pakistan. Computer modelling and analysis of the slope models were performed using Slide (v. 5.0) and Phase2 (v. 6.0) software. integrated use of limit Equilibrium based Probabilistic (lE-P) analysis and finite Element Method (fEM) based shear strength reduction analysis was performed to determine the safe overall slope angle against circular failure. Several pit slope models were developed at different overall slope angles and pore-water pressure ratio (ru) coefficients. Each model was initially analysed under dry conditions and then by incorporating the effect of pore-water pressure coefficients of ru = 0.1, 0.2, and 0.3 (partially saturated); finally, the strata were considered to be fully saturated. it was concluded that at an overall slope angle of 29 degrees, the overall slope will remain stable under dry and saturated conditions for a critical safety factor of 1.3.
{"title":"Open Pit Slope Stability Analysis in Soft Rock Formations at Thar Coalfield Pakistan","authors":"Shafi Muhammad Pathan, A. Pathan, F. I. Siddiqui, M. Memon, Mairaj Hyder Alias Aamir Soomro","doi":"10.24425/ams.2022.142409","DOIUrl":"https://doi.org/10.24425/ams.2022.142409","url":null,"abstract":"Slope Stability Analysis is one of the main aspects of open-pit mine planning because the calculations regarding the stability of slopes are necessary to assess the stability of the open pit slopes together with the financial feasibility of the mining operations. this study was conducted to analyse the effect of groundwater on the shear strength properties of soft rock formations and determine the optimum overall slope angle for an open pit coal mine at thar Coalfield, Pakistan. Computer modelling and analysis of the slope models were performed using Slide (v. 5.0) and Phase2 (v. 6.0) software. integrated use of limit Equilibrium based Probabilistic (lE-P) analysis and finite Element Method (fEM) based shear strength reduction analysis was performed to determine the safe overall slope angle against circular failure. Several pit slope models were developed at different overall slope angles and pore-water pressure ratio (ru) coefficients. Each model was initially analysed under dry conditions and then by incorporating the effect of pore-water pressure coefficients of ru = 0.1, 0.2, and 0.3 (partially saturated); finally, the strata were considered to be fully saturated. it was concluded that at an overall slope angle of 29 degrees, the overall slope will remain stable under dry and saturated conditions for a critical safety factor of 1.3.","PeriodicalId":55468,"journal":{"name":"Archives of Mining Sciences","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49337303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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