Mine Openings Research Articles

Sources of Radon and its Measurement Techniques in Underground Uranium Mines – An Overview

Purpose This study aims to identify the potential sources of radon exhalation and its measurement in underground uranium mines to control the radiation levels within safe limits and protect miners from radiation hazards. Methods An extensive literature review on radon exhalation in underground uranium mines from various sources such as uranium ore, backfill tailings and mine water has been carried out. The influence of different important factors, viz. ore grade, porosity, grain size and moisture content on radon exhalation has been discussed in depth. Different methods for the measurement of radon exhalation from various sources in mines have also been presented in this paper. Results The review of literature revealed that the radon exhalation rate in porous uranium bearing rocks is less affected by the ore grade than in non-porous rocks. The exhalation of radon from backfill tailings is quantitatively more significant than from the uranium ore itself due to higher bulk porosity and enhanced surface area. Thus, porosity is the dominant factor that affects the rate of radon exhalation from rock surfaces into mine openings. Practical implications The knowledge of the sources of radon and quantitative estimation of radon from various sources will be very much useful in the planning and designing of ventilation systems in underground uranium mines. The accurate measurement of radon exhalation in underground uranium mines can be made by choosing the optimum size of accumulation chamber and a suitable radon build-up period in the chamber. Originality/value The study portrays the important sources of radon and its measurement techniques in underground uranium mines based on an extensive literature review. The methods of measurement of radon exhalation from the ore body and backfill tailings in underground uranium mines, used by the authors of this paper, comparatively give more accurate results than previously used methods. Furthermore, the methods are more effective in terms of portability, cost and time for measuring the average radon exhalation across a large.

Sources of Radon and its Measurement Techniques in Underground Uranium Mines – An Overview

Purpose This study aims to identify the potential sources of radon exhalation and its measurement in underground uranium mines to control the radiation levels within safe limits and protect miners from radiation hazards. Methods An extensive literature review on radon exhalation in underground uranium mines from various sources such as uranium ore, backfill tailings and mine water has been carried out. The influence of different important factors, viz. ore grade, porosity, grain size and moisture content on radon exhalation has been discussed in depth. Different methods for the measurement of radon exhalation from various sources in mines have also been presented in this paper. Results The review of literature revealed that the radon exhalation rate in porous uranium bearing rocks is less affected by the ore grade than in non-porous rocks. The exhalation of radon from backfill tailings is quantitatively more significant than from the uranium ore itself due to higher bulk porosity and enhanced surface area. Thus, porosity is the dominant factor that affects the rate of radon exhalation from rock surfaces into mine openings. Practical implications The knowledge of the sources of radon and quantitative estimation of radon from various sources will be very much useful in the planning and designing of ventilation systems in underground uranium mines. The accurate measurement of radon exhalation in underground uranium mines can be made by choosing the optimum size of accumulation chamber and a suitable radon build-up period in the chamber. Originality/value The study portrays the important sources of radon and its measurement techniques in underground uranium mines based on an extensive literature review. The methods of measurement of radon exhalation from the ore body and backfill tailings in underground uranium mines, used by the authors of this paper, comparatively give more accurate results than previously used methods. Furthermore, the methods are more effective in terms of portability, cost and time for measuring the average radon exhalation across a large.

Investigation of hydraulic fracture growth near a mine opening

The behavior of a hydraulic fracture near the mine opening in a plane-parallel formulation has been investigated. The case was considered, when the rock was under hydrostatic pressure, and the initiating crack was oriented in the direction of mine opening. It is found that the fracture path is greatly influenced by the ratio of hydrostatic pressure and critical tensile stress of rock. It is shown that when the hydrostatic pressure increases with respect to critical tensile stress, the fracture begins to deviate from the mine opening earlier and does not reach its surface. It is also shown that under various conditions, fractures cannot bypass the mine opening completely due to the occurrence of severe strains in the area between the opening and fracture.

Navigation system for heading machines in potash mines

Mining operations at potash mines are carried out by heading machines. Setting of a direction and control of the movement of the machines is carried out by the mine surveyor and by the machine operator in the manual mode. The lack of automation of this process during production leads to large labor costs of the mine surveying service, while the experience of the machine operator affects accuracy of maintenance of a specified course. Currently, there are no ready-made technical products for automating the process of setting the course and controlling the movement of heading machines. This paper deals with the implementation of the navigation system for heading machines in the underground mines of Uralkali company. At the mines of Uralkali, the requirements for the accuracy of such a system are dictated by the requirements for the accuracy of mine surveying support for underground mining operations in driving new roadways. Possible ways of constructing navigation systems and the problems of their application are considered. The analysis of the existing methods shows that the most promising option for navigation of heading machines in underground mine openings are the systems based on the principles of inertial navigation. To use such systems in underground mines and to ensure the required accuracy, the technical requirements for the systems are formulated. It is shown that modern strapdown inertial navigation systems satisfy the required accuracy. On their basis, a prototype of the heading machine navigation system was developed, and its ground tests were carried out. The achieved accuracy of the system makes it possible to proceed to testing of a real heading machine in a mine. The study was supported by the Russian Science Foundation, Project No. 19-77-30008.

Housing conditions and respiratory health in children in mining communities: An analysis of data from 27 countries in sub-Saharan Africa

BackgroundPoor housing conditions, such as poor building materials and weak structures as well as high levels of indoor air pollution, are important risk factors for a broad range of diseases, including acute respiratory infections (ARI). In mining areas, research on the determinants of respiratory health predominantly focuses on exposures to outdoor air pollutants deriving from mining operations. However, mining projects also influence the socioeconomic status of households, which, in turn, affect housing quality and individual behaviors and, thus, housing quality and levels of indoor air pollution. In this study, we aimed to determine how proximity to an industrial mining project impacts housing quality, sources of indoor air pollution, and prevalence of ARI. MethodsWe merged data from 131 Demographic and Health Surveys (DHS) with georeferenced data on mining projects in sub-Saharan Africa (SSA) to determine associations between housing quality, indoor air pollution sources, and child respiratory health. Spatial differences in selected indicators were explored using descriptive cross-sectional analyses. Furthermore, we applied a quasi-experimental difference-in-differences (DiD) approach using generalized linear mixed-effects models to compare temporal changes in household and child health indicators at different operational phases of mining projects and as a function of distance to mines. ResultsFor cross-sectional analyses, data of 183,466 households and 141,384 children from 27 countries in SSA were used, while 41,648 households and 34,406 children from 23 SSA countries were included in the DiD analyses. The increase in the share of houses being built from finished building materials after mine opening was more than 4-fold higher (odds ratio (OR): 4.32, 95% confidence interval (CI): 2.98–6.24) in close proximity to mining sites (i.e., ≤ 10 km) compared to areas further away (i.e., 10–50 km). However, these benefits were not equally distributed across socioeconomic strata, with considerably weaker effects observed among poorer households. Increases in indoor tobacco smoking rates in close proximity to operating mines were twice as high as in comparison areas (OR: 2.06, 95% CI: 1.15–3.68). The cross-sectional analyses revealed that traditional cooking fuels (e.g., charcoal, dung, and wood) were less frequently used (OR: 0.27, 95% CI: 0.23–0.31) in areas located in close proximity to mines than in comparison areas. Overall, no statistically significant association between mining operations and the prevalence of symptoms related to ARI in children under the age of 5 years was observed (OR: 0.78, 95% CI: 0.29–2.07). ConclusionsMines impact known risk factors for ARI through diverse pathways. The absence of significant changes in ARI symptoms among children is likely the result of counteracting effects between improvements in housing infrastructure and increased exposures to air pollutants from outdoor sources and tobacco smoking. For mining projects to unfold their full potential for community development, we recommend that impact assessments move beyond the mere appraisal of mining-related pollution emissions and try to include a more comprehensive set of pathways through which mines can affect ARI in exposed communities.

Mining Open Government Data for Business Intelligence Using Data Visualization: A Two-Industry Case Study

The business intelligence (BI) market has grown at a tremendous rate in the past decade due to technological advancements, big data and the availability of open source content. Despite this growth, the use of open government data (OGD) as a source of information is very limited among the private sector due to a lack of knowledge as to its benefits. Scant evidence on the use of OGD by private organizations suggests that it can lead to the creation of innovative ideas as well as assist in making better informed decisions. Given the benefits but lack of use of OGD to generate business intelligence, we extend research in this area by exploring how OGD can be used to generate business intelligence for the identification of market opportunities and strategy formulation; an area of research that is still in its infancy. Using a two-industry case study approach (footwear and lumber), we use latent Dirichlet allocation (LDA) topic modeling to extract emerging topics in these two industries from OGD, and a data visualization tool (pyLDAVis) to visualize the topics in order to interpret and transform the data into business intelligence. Additionally, we perform an environmental scanning of the environment for the two industries to validate the usability of the information obtained. The results provide evidence that OGD can be a valuable source of information for generating business intelligence and demonstrate how topic modeling and visualization tools can assist organizations in extracting and analyzing information for the identification of market opportunities.

Experimental Investigation of the Mechanical Properties of Sandstone–Coal–Bolt Specimens with Different Angles under Conventional Triaxial Compression

The complex nonlinear mechanical behavior of the combined system of rock and coal surrounding mine openings is a major obstacle for excavation, stability, and support design in mining thin coal seams. In this paper, the triaxial compression failure characteristics and mechanical response of sandstone–coal (SC) specimens with different combination angles are determined. In addition, the influence of the anchor bolt on the mechanical properties of SC specimens is also considered. The results show that the mechanical parameters of the SC and sandstone–coal–bolt (SCB) specimens are different from those of other intact rocks and are substantially affected by the angle. The peak axial strain and triaxial compressive strength (TCS) of the specimens decreased with increasing angles. To comprehensively analyze the phase mechanical characteristics of the specimens and the differences between them, we also established the crack initiation stress index (CI) and crack damage stress index (CD) to evaluate the specimen fracture process. The established stress indices CI and CD can accurately describe the roles of the bolt and angle of the SC and SCB specimens. The bolt can enhance the mechanical properties of the SC specimen after reaching the peak load, restrain the development of cracks, and ensure that the specimen maintains integrity. It should be noted that this type of SCB system is in line with the long-term stability of roadway support engineering applications.

Prediction and Assessment of Rock Burst Using Various Meta-heuristic Approaches

One of the utmost severe mining catastrophes in underground hard rock mines is rock burst phenomena. It can lead to damage to mine openings and equipment as well as trigger accidents or even threat to life as well. Due to this, a number of researchers are forced to study some easy-to-use alternative methods to predict the rock burst occurrence. Nevertheless, due to the extremely multifaceted relation between mechanical, geological and geometric factors of the mines, the conventional prediction methods are not able to produce accurate results. With the expansion of machine learning methods, a revolution in the rock burst occurrence has become imaginable. In present study, three machine learning methods, namely XGBoost, decision tree and support vector machine, are utilized to predict the occurrence of rock burst in various underground projects. A total of 134 rock burst events were gathered together from various published literatures comprising maximum tangential stress (MTS), elastic energy index (EEI), uniaxial compressive strength and uniaxial tensile stress (UTS) that have been used to develop various machine learning models. The performance of machine learning methods is evaluated based on the accuracy, sensitivity and specificity of the rock burst prediction.

Bronze Metallurgy in Southeast Asia with Particular Reference to Northeast Thailand

The long-awaited definitive chronology for the period from the initial use of bronze metallurgy to the end of the Iron Age on the Khorat Plateau of Northeast Thailand has received near universal acceptance. In this review, we trace how bronze was deployed, and assess its social impact from the late Neolithic communities that first encountered metal to the civilization of Angkor. We identify eight phases that, for the prehistoric period, centred on the anchor site of Ban Non Wat, beginning in the eleventh century BC with imported copper axes and the opening of the first mines and associated smelting sites. This was followed in the second and third phases of the Bronze Age by a dramatic increase in mortuary wealth in the graves of social aggrandizers. After about eight generations, bronzes were locally cast in bivalve moulds. However, no further elite burials were found and bronze mortuary offerings were very rare. From about 400 BC, the opening of seaborne exchange networks, the establishment of dynastic China and climatic change then stimulated marked regionality. On the Khorat Plateau, many more bronzes were interred with the dead, but casting activity in the consumer sites declined. In the early centuries AD, increased aridity stimulated an agricultural revolution as sites were ringed by reservoirs and wet rice was grown in ploughed fields. This was accompanied by a surge in the range and number of bronzes with the new social elite that within a century led to the formation of early states. The new royalty now sponsored bronze statues, leading directly on to the dynastic foundries of Angkor, when massive bronzes reflected royal divinity.

Effect of Concentration and Suspension Agent (HPMC) on Properties of Coal Gangue and Fly Ash Cemented Filling Material

Cemented coal gangue-fly ash backfill (CGFB) mixtures are utilized as the filling materials for backfilling the underground openings in coal mines. The freshly prepared CGFB slurries are commonly transported into the gobs through a pipeline. The mixture ratio of slurry concentration and suspending agent (HPMC) plays an essential role in transporting the slurry to goaf smoothly and efficiently. In this paper, the influence of slurry concentration and HPMC on the performance of coal gangue-fly ash cemented filling material was studied based on the response surface method. The prediction model of CGFB slurry slump flow, segregation rate, and bleeding rate was constructed. It is concluded that the segregation rate and slump flow of slurry are more sensitive to the variation of concentration. On the other hand, the bleeding rate of slurry is more sensitive to the change of HPMC content. Based on the established model, the reasonable mix proportion range of slurry concentration and suspending agent (HPMC) was obtained. In addition, three new CGFB mixtures have been tested, and the experimental results are in good agreement with the predicted values.

Investigating the outcome for South African coal supply to the domestic market when faced with declining demand for exported coal

This paper investigates the implications for coal supply security for the domestic South African market when faced with weaker export demand. It expands on a previously introduced model of domestic coal trade, DOTRAMOD, by accounting for mining profit, the opening of new mines and the closing of loss-making mines. The results indicate that declining demand for exported coal would result in declining profits for multi-product mines. This would lead to the closure of some mines and reduced coal supply to domestic power producers. These results highlight the importance of the mine investment problem in commodity market studies.

Urbane prilike u centralnim i južnim delovima Srbije u doba kralja Milutina

The era of the reign of the King of Milutin represents an important turning point in the history of the medieval Serbia. It cannot be said he was the initiator of either economic or urban development, but it can be noticed in his era there was a considerable step in this direction. The King Milutin himself showed an enviable energy thanks to it he enlarged his state and introduced numerous changes. By annexation of the areas in the south, the part of Serbian state became a territory which inherited the urban culture being inherited from the antique and renewed during the Byzantine rule. By the adoption on Byzantine patterns of behaviour, the urban culture was being adopted as well. The second important step toward the process of urbanization was the opening of mines and appearance of market places in their vicinity. In the era of the King Milutin in documents for the first time appears seven mining market places: Rudnik, Trepča, Rogozno, Gračanica (Janjevo), Novo Brdo, Lipnik and Trešnjica.Their characteristic was that they represented centres in which in initial period lived Saxons, but by the time local inhabitants will have been moved, which will be dealing with mining industry, craft, commerce and services provision. As the Saxon's community was restricted and without additional influx, by the time it will have been had assimilated into the Serbian one for those settlements as well. Close to Saxons, at least as per religion, were merchants coming from the Coast, and which were called by domestic population Latins. The King Milutin had issued several charts and letters to citizens of Dubrovnik by which he confirmed privileges and security to them. In that sense, it is important the chart issued in 1302 in Vrhlab. Besides the citizens of Dubrovnik, citizens of other coast towns dwelled in mining market places including some Italian communes due to which they represented multicultural milieu. In the era of the King Milutin these settlements were in their infancy, and the lack of sources did not allow their significant consideration. Nevertheless, those settlements represent a solid fundament and initiator for further urban development which will follow in subsequent decades.

Toxic elements in the с1 coal seam of the Blahodatna mine of Pavlohrad-Petropavlivka geological and industrial area of Donbas

The features of the distribution of toxic elements in the c1 coal seam of «Blahodatna» mine field are considered. The research aims to establish regularities in the distribution of toxic elements in the coal seam c1 of Blahodatna mine of Pavlohrad-Petropavlivka geological and industrial area of Donbas. Samples were taken from mine opening (reservoir samples, selected by the trench method and from duplicates of drill core personally). Content of toxic elements was determined by quantitative emissive spectrum analysis. The values of the main descriptive statistical indicators were calculated. With the aim of identify the composition of the geochemical associations, correlation coefficients (r) were calculated between the content of the toxic elements. In a single geochemical association united elements in which the relationship between the content is described by the correlation coefficient that exceeds 0,5, with a significance level of at least 95%. As a result of the performed studies, maps of the isoconcentrate of toxic elements and maps of the regional constituent of their contents by the area of the mine field were constructed. Linear regression equations are calculated between the concentrations of toxic elements and the main technological parameters of coal. Analyzing the result of statistical processing of geochemical information and geological and structural characteristics of the coal seam c1 of «Blahodatna» mine field allowed us to establish, that the formation of the association of cobalt, nickel, vanadium, lead, chrome and manganese is associated with the enrichment of contact zones of the coal seam by these elements and is genetically is due to influence of adsorption and reductive-oxidative barriers on the migration of matter during the diagenesis and catagenesis of coal-bearing series. The main scientific importance of the results of the performed studies is the establishment of genetic causes that have a significant effect on the distribution of toxic elements in coal seam of c1.

Ranking of potential coal deposits in order to make investment decisions to open new mines in Serbia

For investments in the field of coal exploitation in the Republic of Serbia, in the future investment analyzes show significant results, although the "Green Agenda" aims to reduce until the end of this process in 2050. New ore and mineral deposits are also emerging, which will also require the opening of new mines in the future, and the choice of investment variant by ranking potential deposits directly depends on the amount of reserves but also on high environmental standards.

Estimation of Antileakage Grouting Influence on Waterproof Stratum Integrity

In case of significant deformation of salt rocks around mine openings traditional methods of preventing potash mines from flooding, such as backfilling, sometimes can’t guarantee the preservation of waterproof stratum (WPS) integrity. One of the possible methods to prevent water inflow into mine workings is injection of grouting material in order to create antileakage screen ensuring waterproofing of fault zone in WPS. Methodical approaches to estimation of pressure from grouting contribution into alteration of WPS stress-strain state are discussed and main problem statements are introduced in the paper. The use of suggested approaches is illustrated for the case of hazardous situation at south-east part of BKRU-4 mine (Berezniki, Russia). Mathematical modelling of different scenarios of grouting material injection and rock mass response in the concerned area were held out and maximum safe pressure of grout pumping were found.

Всплывание пустот в приповерхностном углепородном массиве Донбасса

Long-term research has proved the connection between old mine workings preserved at the outcrops of coal seams and land subsidence, and sinkhole collapse. Now the causes and types of such disturbances are determined, the most dangerous of which are caves, over various types of the abandoned mine workings. In addition to it, a method has been developed and improved for assessing the hazard rate of any abandoned working (cavity) with relation to sinkholes for mining and geological conditions of the Donets Basin. At the same time, a number of cases are known when cavities wiped out due to the failure of the overlying rocks reappeared on the upper levels, threatening to generate surface depression. Thus, the former, but already liquidated cavity seemed to pop in the overlying rocks. The understudied process of cavities moving in the subsurface coal-bearing strata from the places of their original location towards the surface in the Donets Basin is described. The computation of stage-by-stage popping of relatively undestroyed mine opening (cavity) in coalbearing strata of different strength is made. The conditions and factors contributing to the popping of the remaining cavities towards the overlying levels are determined. An assumption (hypothesis) on the inevitability of popping of any abandoned working or cavity preserved on the upper levels, with a favorable combination of the affecting factors is made. The necessity for this process to be taken into account in assessing the hazard rate of the surface areas undermined by the abandoned mine workings at shallow depths due to their potential capability of making sinkholes is demonstrated. The effective reference documents regulating the procedure for assessing the hazard rate of abandoned mine workings (cavities) at shallow depths do not take into account popping of cavities that hurts correctness of the results obtained for them.

Evaluation of load transfer mechanism under axial loads in a novel coupler of dual height rock bolts

The effective reinforcement of two or more overlying layers of mine openings in a single installation is usually done by coupling of two standard rock bolts mainly during the extraction of medium-thick coal seams. However, field observations show that the couplers of multiple bolts often degrade or break mostly at their connections. These types of failures can be avoided by strengthening the couplers of such multi-bolts assemblies. To achieve this, a novel threaded coupler system with an expansion shell was suggested in this paper. The newly designed coupler consists of a threaded tapered-plug-cum-connector with an expansion shell for connecting and tightening two standard rock bolts. An analytical model for evaluating the load distribution along the coupler subject to axial load was derived. Numerical analysis was performed to analyse the load transfer, deformation, and strains across the coupler including the factor of safety for the bolt-coupler-resin and bolt-coupler-expansion shell. The results validated the analytical model of the proposed coupler design, which provides better anchorage near the interface of the host rock mass. Thus, the developed coupler design would reduce the failures of the proposed coupler and stabilize laminated roof strata above the medium-thick coal seams in underground mines.

ЛАБОРАТОРНІ ВИПРОБОВУВАННЯ КОМБІНОВАНИХ ПОДОВЖЕННИХ СТРУКТУРНИХ ЕЛЕМЕНТІВ ДЛЯ КОНСТРУКЦІЙ КРІПЛЕННЯ ГІРНИЧОЇ ВИРОБКИ

The stress-strain state of test specimens of the new combined structure of support of a mine opening under loads is studied. The test specimens are compound modular elements of the designed earlier combined structure of support. Every single modular element is the triangular prism, consisting of a reinforced concrete slab and a steel grid made of tube web members. The slab and web members are grouped in a complete element while concreting the slab. The tension sensor’s method of experimental investigation is applied to the testing specimens. Tests of specimens are carried out under the load forced with cargoes. Loads are set in the ways that to simulate service conditions, counting the most adverse. Design features of the support and test specimens are shown. Particulars of the support and its elements, production technology, assemblies as well as the sizes are briefly described. The methodology of testing specimens, as well as the analysis of the outcomes, are presente.

Geological exploration and industrial development of the Bilozerskyi iron ore region

The latest information on geological and structural position and geological structure of deposits of rich iron ores of the Belozerskyi iron ore district is summarized, and the state of their industrial development is characterized. During the exploitation of the Pivdenno-Bilozirske and Pereverzivske deposits, due to geological study, mining exploration and additional exploration of deep horizons, specialized and feasibility study a significant amount of new geological data has been received. This data allowed to clarify the position, morphology and internal structure of ore bodies, qualitative, physical and mechanical properties of ores and enclosing rocks, hydrogeological, geological, engineering and mining conditions. The article presents the results of the analysis and interpretation of the latest geological information and actual data on the mine development of deposits – modern views on the geological structure of objects, the characteristics of the basic natural conditions and parameters that affect the efficiency of industrial mining of rich iron ores.
 The state of geological prospecting in the region is very uneven. The most studied are the Pivdenno-Bilozirska and Pereverzivska fields, which are currently being developed.
 The rich iron ores of these deposits are classified as high quality in both Ukraine and Europe. These ores do not require beneficiation and are suitable for agglomeration and open-hearth process. This circumstance helps to reduce the cost of mining and increase the commercial efficiency. For the mine development of both deposits, a common infrastructure is used – permanent mine openings, mine shafts, support facilities and services. Joint development of the deposits will ensure the long-term stable operation of the plant without reducing the production of rich iron ores.
 The deposits are characterized by difficult mining and technical operating conditions. The ore deposits are covered by a cover up to 250–350 meters of loose water-saturated sedimentary deposits. The iron ore strata and the host rocks have heterogeneous physical and mechanical properties.
 Iron ores are mined using a productive level-room system. Empty rooms are filled consolidating stowing. The advanced drainage and continuous groundwater withdrawal from mines are used in the mining process.
 The progressive system of iron ores mining ensures: preservation of the productivity and quality of aquifers, which are used for municipal water supply; preservation of the earth’s surface from avalanches and landslides in the mining area; stable environmental conditions at the plant area and in the surrounding area; efficiency and completeness of extraction of iron ores from the bowels; the optimal level of economic indicators of the enterprise.

Ventilation design, construction, and commissioning to meet production expansion requirements in a potash mine

ABSTRACT The Rocanville mine has recently increased its site production nameplate capacity from 3.0 to 6.51 million tonnes of potassium oxide per annum. The production expansion consisted of doubling its processing capacity by building a second mill facility, increasing the ore hoisting capacity by converting the existing service shaft into a production shaft, and increasing mine production capacity by nearly tripling the production mining machine fleet and opening new ore reserves. A new remote shaft was also constructed to act as a service shaft. This article presents the design of the mine ventilation system that meets the post-expansion production requirements, the construction of the ventilation facilities, and the commissioning that was implemented in phases to permit a controlled ramp-up to full ventilation capacity with minimal disruption to mine operations.