Underground Mining Method Research Articles

Analysing the Role of Safety Level and Capital Investment in Selection of Underground Metal Mining Method

It is one of the important tasks to select a suitable mining method for economic and safely extraction of the specific ore deposit. The selection of individual mining methods depends on multiple factors like dip, shape, thickness, depth, grade distribution, RMR (rock mass rating) of ore and adjacent strata, and RSS (rock substance strength) of ore and adjacent strata. The present study aims to analyse the role of two extrinsic factors (safety and capital) in the selection of underground metal mining method. A fuzzy-AHP decision making model is developed to analyse the possible changes in the mining method with different levels of safety and capital. The study considers seven alternatives or mining methods (block caving, sublevel stoping, sublevel caving, room and pillar mining, shrinkage stoping, cut and fill stoping and square set stoping) in the model. The results revealed that the preference level or ranking of different mining method in a particular condition like low safety (SAL), medium safety (SAM), high safety (SAH), low capital (CL), medium capital (CM), and high capital (CH) remains same for different decision-making attitude and uncertainty level.

Study and evaluation of the stability of underground mining method used in shallow-dip vein deposits hosted in poor quality rock

Purpose.This article proposes to analyze and determine the mining design for shallow-dip deposits hosted in poor quality rock. Methods. We used the UBC tool to find the optimal exploitation method, the Rock mass rating (RMR) and Q-system (Q) to determine the optimal mining stope and the recommended rock support, the numerical modeling by RS2 software with a variety of geotechnical, geometrical, and technical conditions to analyze the evolution of the unstable zone width and the maximum total displacement around the stope after excavation. Findings. The optimum mining method designated by the UBC tool for this type of deposit is the cut and fill. By projecting the obtained RMR and Q-system values on the design graph, it is concluded that the operating stope is located in the stable zone with a height of 3 m, and bolting support is recommended. The simulation by RS2 software reveals that the optimal mining design that can be used to mine shallow-dip vein deposits hosted in poor quality rocks consists of a 3 m high stope and a 75° dip with cemented backfill. Originality.This work presents a study to choose the most suitable underground mining method and mine design for shallow-dip deposits hosted in poor quality rock. Practical implications.In the mining industry, the success of operating an underground mine is conditioned by the selection of the appropriate method, of the mining design and dimensioning of a rock support adapted to the nature of the rock, and excavation geometry according to the type and nature of the deposit.

Trends in Underground Mining

In this document, we will talk through information collected on all trends in mining in the underground environment as much as what happens in the world as or new machinery America provides the highest mining production in underground mining. We often discover opportunities for improvement in both productivity and costs. Of all these methods, braking is not only the most common, but also offers the largest share of overall production, nearly 50 percent. These underground mining methods are often determined by the deposits and the economics of mining and are therefore somewhat beyond the control of the operator(Trends in underground mining for gold and base metals | McKinsey, s. f.)

Mathematical Programming Application in Sublevel Caving Production Scheduling

Production scheduling determines the most beneficial mining sequence over the life of a mine. Developing a schedule that meets all mining aspects can substantially reduce mining costs and increase profitability. Among all underground mining methods, the sublevel caving method is a common method with moderate development requirements, a high production rate, and a high degree of mechanization and flexibility. None of the manual planning methods and heuristic algorithms used in commercial software will lead to a truly optimal schedule. Mathematical programming models, particularly mixed-integer programming (MIP), have been applied to provide an operationally feasible multi-time-period schedule in sublevel caving. However, confined blasting conditions, chaotic material flow, and frequent mixing of ore and waste while loading broken ore at the drawpoint make the sublevel caving method unique when producing a holistic plan. This paper reviews all mathematical programming models presented in sublevel caving production scheduling, highlights the inherent characteristics of the sublevel caving that affect production, and puts forward some promising ideas for future works.

The Unseen: A Case Study of Innovative Methods for Investigating Historic Mine Workings

Canadian mining operations have long been key contributors to economic vitality. This has resulted in Canada standing at the forefront of implementing best practices that relate to mine closure projects. In the case of closing historic mines this can be a particularly challenging task as often the level of information available is much less than active mines preparing to close. Closing historic mines provides an opportunity to apply new, and innovative methods to collect the data required to design and execute a successful mine closure plan. The site discussed in this study is in northern Canada and used interconnecting open pit and underground mining methods while in operation but has been closed for over half a century. Historic documents indicate that the mine was closed after a failure occurred at depth and some backfill material was lost. A pond currently exists where the open pit was located. This study is Rock Mechanics focused and discusses the methods used to assess the geometry and stability of the historic mine workings. The need for innovation stemmed from the limited historic plans and documentation that existed. Empirical methods suggested that the crown pillar at the site was unstable and should have failed, which did not align with on-site observations. Therefore, an alternative method of assessing the stability was required which involved undertaking bathymetric and three-dimensional sonar surveys to gain a better spatial understanding of the open pit and underground environment. The surveys confirmed that there were no visible signs of instability in the areas where the surveys were done. Advantages and limitations exist for the methods used to complete the survey and use the survey results during this investigation. These will be discussed in this paper.

Contribution to the geomechanical stability of marble underground openings using backfill

A stability analysis on the possibility of using room and pillar underground mining method, in a marble quarry in Alentejo (Portugal) with backfill, is presented. Given the data provided by the laboratory tests over marble samples and in situ tests as well as a thoroughly geology acknowledgment of the area, a new excavation design was presented for the underground phase, using Finite Element analysis, where global and local stability is assessed. Moreover, the innovative idea, for marble underground quarries, was to contribute to the circular economy and the current environmental policies by making a use of the quarry’s waste rock, as the principal aggregate for a backfill material, that not only reduces the impact of wastelands in the surface but also acts as support for the newly excavated area leading to residual pillars recovery. Given this, an overview of the stress displacement is presented, and the main potential instability zones are assessed. The results are a quantitative contribution to the characterization of the rock mass for alternative ways of ornamental marble production in this region.

Mining industry in Mozambique

At present time,Mozambiqueis called the “Rising Star of South Africa” mainly due to the rapid development of its mining industry. Mineral resources sector ofMozambiqueis one of the most dynamically developing sectors of the country’s economy.China,BrazilandIndiahave recently become the main partners forMozambique. Recently, a number of projects is being implemented in the country, for example, Auroch Minerals Manica Gold in gold production. Increasing coal production is connected with commissioning of the Moatize open pit, which is being developed by Brazilian Vale Company, as well as Benga mining company owned by Indian ICVL consortium. The analysis of the extraction of certain mineral types inMozambiquepresented in the paper demonstrates general picture of mining industry development in the country. The analysis findings allow identifying the causes of negative phenomena in the industry, manifesting themselves in decreasing production of certain types of minerals. For instance, the main reasons for the decline in coal production were dropping labor productivity, deterioration of mining conditions, and depletion of the most accessible coal reserves, extractable by open pit mining. In this regard, development of underground mining methods providing for opening of deep deposits by vertical shaft sets is highly relevant. The experience of the neighboringRepublicofSouth Africashows that, in the mining and geological conditions of the south of the African continent, highspeed shaft sinking methods accelerating deposit development can be successfully applied.

Geotechnological structure of a combined opencast and underground mining method in the condition of integrated development of coal deposits

A combined opencast-to-underground mining method is widely used for final extraction of border zone coal reserves and extracting areas with limited and non-technological reserves. The idea of the method is that coal is extracted by opencast method and continued by underground mining using highwall mining complex, mobile mining mechanical equipment, augers, mechanized complexes and water jetting facilities.

The checkerboard effect and mineral resource reporting of underground mineral resources

ABSTRACT The goal of a Mineral Resource statement is to estimate the in-situ tonnage and grade that might reasonably be expected to be extracted using the contemplated mining methods. Despite the transition by the mining industry to the use of computer-aided methods for preparing Mineral Resource estimates, the fundamental realities of complying with the CIM Definition Standards requirement of “Reasonable Prospects for Eventual Economic Extraction” (RPEEE) have not changed. Computer-aided block modeling can result in an irregular, patchwork of blocks above and below cutoff grade, termed the checkerboard effect. In such cases, for underground mining methods, strict application of a block cutoff grade does not consider the impact of any internal dilution blocks that may be present, while also potentially including blocks above cutoff grade that may not have sufficient spatial continuity. Considering the block dimensions relative to the selectivity of the potential underground mining method, this can result in material errors in Mineral Resource statements. The impact of the checkerboard effect varies from deposit to deposit. While several techniques are currently employed by Mineral Resource practitioners to ensure compliance with the RPEEE requirement of a Mineral Resource, practitioners are encouraged to develop additional methods and techniques that provide reasonable results.

Sensitivity analysis of fuzzy-analytic hierarchical process (FAHP) decision-making model in selection of underground metal mining method

This study aims to analyse the sensitivity in decision-making which results in the selection of the appropriate underground metal mining method using the fuzzy-analytical hierarchy process (FAHP) model. The proposed model considers sixteen criteria for the selection of the most appropriate mining method out of the seven. The model consists of three-layer viz. the first layer represents the criteria (factors which influence the mining method), the second layer represents the sub-criteria (categorisation of the factors) and the third layer represents the alternatives (mining methods). The priority of the different mining methods was determined based on global weights. The global weights of seven mining method were determined using a different fuzzification factor under different decision-making attitudes (optimistic, pessimistic and unbiased). The sensitivity of the decision-making results was analysed in order to understand the robustness of the model.

A Numerical Simulation of Bolt Grouting Reinforcement for Reducing the Optimum Dimensions of Jointed Hard Rock Pillars in Faryab Chromite Mine (Iran)

The maintaining needed for underground mining operations is satisfied by installing a support system or leaving an ore pillars. These pillars need to have enough stability to bearing the overburden loading. Designing a pillar with optimum dimensions is the most significant issues in room and pillars underground mining method. The purpose of this paper is to determine the optimum dimensions of rock pillars in Faryab mine and reducing their dimensions using grouting technology based on a numerical simulation. The modeling results, before grouting operation, show that in the area where the pillars height is 12 m, the pillars with a width of 8 m are stable and the pillars with a width of 7 m are unstable and are on the verge of destruction. So a pillar with a width of 7 m is considered in order to stabilization. 2D and 3D numerical modeling results show that using bolt grouting in jointed rocks, improved the strength properties and as a result increase the strength of pillars and make it completely stable. Accordingly, in the rock masses that can be injected, the grouting operation can reduce the pillars width and increase the extraction recovery.

Evaluation of Underground Mineable Reserve in Presence of Grade and Commodity Price Uncertainties

The uncertainty-based mine evaluation and optimization have been regarded as a critical issue. However, it has received less attention in the underground mines than in the open-pit mines due to the diversity of the underground mining methods, and the underground mining parameters' complexity. The grade and commodity price uncertainties play essential roles in mining projects. Mine planning by not incorporating these uncertainties is accompanied by risks. The evaluation and risk assessment of the mine plans is possible through evaluating the mineable reserve in the presence of such uncertainties. In the present work, we evaluate the effects of grade and commodity price uncertainties on the underground mining stope optimization and the resultant mineable reserve. In this regard, the stope boundary is studied both deterministically and stochastically in the presence of the grade and price uncertainties. For this purpose, in this work, we implement the conditional simulation in order to generate equally probable ore reserve models. Furthermore, we optimize the stope boundary using the floating-stope algorithm in each realization. Several decision support criteria including the 'mineable reserve,' 'metal-content,' 'profit,' and 'value-at-risk' are defined to assist the decision-maker in uncertain conditions. Finally, a procedure is defined in order to consider two types of uncertainty sources simultaneously in underground mining. It will guide the decision-maker toward the most appropriate stope boundary that best fits the mining company's requirements. The procedure is implemented in a bauxite mine, and the optimal stope boundary is determined concerning the different criteria.

Cost competitive analysis of large-scale gold mines in Ghana from 2007 to 2016

The gold mining industry is a major contributor to the economy of Ghana. However, this contribution has been declining over the past decade. This decline coupled with the importance of the industry to the country’s economy necessitated the need to analyse the performance of companies within the industry. Therefore, a cost performance analysis of Ghana’s major gold mines was done in this paper for the period 2007 to 2016 using industry cost curves. A correlation coefficient analysis was also done to identify the key cost drivers in Ghana. This paper further analysed the cost competitiveness of Ghana’s gold mining industry against other gold producing countries in the world. From the analysis, it was found that Newmont’s Ahafo and Akyem mines were consistent low unit cost producers. Both mines benefited from economies of scale and high metallurgical recovery rates. On the other hand, AngloGold Ashanti’s Obuasi and Golden Star’s Bogoso mines were found to be consistent high unit cost producers due to low-productive and labour-intensive underground mining methods used and very low metallurgical recovery rates, respectively. Finally, the study revealed that Ghana’s gold mining industry was not cost competitive when compared to other gold-producing countries over the analysis period.

Strategies for surface crown pillar design using numerical modelling – A case study

The extraction of shallow ore deposits using underground mining methods rather than open pit mining is not uncommon nowadays, especially with the increased environmental constraints. Such scenario results in the creation of a surface crown pillar - the rock cover consisting of ore rocks that separate the uppermost stopes from the overlying surface. Although the problem of surface crown pillar stability has been researched for more than 30 years, the design guidelines are still limited. This is largely because of the wide variety and complexity of site-specific conditions. Thus, empirical and analytical methods are only used for preliminary design and more comprehensive methods such as numerical modelling must be adopted for the final design. This paper investigates strategies for the design of a surface crown pillar at a gold mining operation having a shallow, steeply dipping orebody that extends underneath an existing tailings storage facility. The orebody is in the vicinity of two regional faults. In this study, numerical modelling approaches are developed using the finite difference code FLAC3D 7.0. Critical factors such as in-situ stress regime, major geological structures, mining sequences, slanted surface topography and surcharge are considered. A model parametric study is carried out to investigate the effect of fault properties and horizontal stress ratios on surface crown pillar stability. Mining-induced surface subsidence is then analyzed to shed light on the anticipated maximum differential settlement and distortion developed in the tailings dam foundation as a result of the mining activities. Predicted differential settlement results could serve as another criterion for crown pillar sizing from the perspective of overlying infrastructure stability. The reactivation of two nearby faults due to mining activities is also explored. It appears that larger shear displacements occur on the fault that is parallel to the orebody strike compared to the cross fault.

Trends in Underground Mining

In this document, we will talk through information collected on all trends in mining in the underground environment as much as what happens in the world as or new machinery America provides the highest mining production in underground mining. We often discover opportunities for improvement in both productivity and costs. Of all these methods, braking is not only the most common, but also offers the largest share of overall production, nearly 50 percent. These underground mining methods are often determined by the deposits and the economics of mining and are therefore somewhat beyond the control of the operator(Trends in underground mining for gold and base metals | McKinsey, s. f.)

Improvement of production control of coal mining enterprises with underground mining method

Production safety is one of the problems of competitiveness of underground mining enterprises, one manifestation of which is the reduction and minimization of the number of accidents and incidents of personal injury or even death. To solve this problem, it is necessary to improve the system of production control of coal mines in order to eliminate these factors. Relative indicators of accidents and injuries at underground coal mines of Russia in comparison with the average indicators are considered, and also importance of the human factor in the occurrence of dangerous production situations and the evaluation of their causes and effects are revealed. In addition, the article considers the most common violations of safety requirements for underground coal mining, analyzes the experience of foreign countries in improving the production control system, assesses the possibility of its application for improving production control at Russian coal mines, and determines main areas for implementing a risk-based approach at coal mining enterprises.

Determination of an Optimum Interface between Open-Pit and Underground Mining Activities in Mazinu Coal Mine of Tabas Power Plant

Due to the gradual deepening of the Mazinu coal seams from the ground surface, both the open-pit (OP) and underground (UG) mining methods can be applied for extracting them. Thus, it is a necessity to determine the interface of these mining methods optimally. The present paper aims to determine this interface by generating different scenarios using the OP phases and their relative underground stopes, and comparing them with each other. In this regard, an economic block model is created based on the calorific value of the coal portions involved by each block along with the required economic and technical parameters. Then using the Lerchs-Grossman algorithm, the OP phases are created. Proportional to each phase, the production scheduling of underground stopes is executed. Finally, in order to opt the best scenario, the net present value of the whole project (OP & UG) achieved from different scenarios are compared with each other. The results obtained indicate that the optimum interface of the OP and UG mining activities correspond to the ultimate OP limit with a maximum depth of 200 m from the ground surface.

Methodology for underground mining method selection

Methodology for underground mining method selection

Methodology for underground mining method selection

Methodology for underground mining method selection

Research and substantiation of rational parameters of drilling and blasting operations when using emulsional explosives in underground mining

Purpose. To determine and substantiate the rational parameters of drilling and blasting operations using emulsion explosives such as Ukrainit PP-2B and to develop a methodology for their determination for the effective development of mineral deposits underground mining method. Methodology. To achieve this goal, a set of modern research methods was used, including an analysis of literature sources, design documentation and the practice of mining iron ore deposits at great depths, theoretical generalization of laboratory and industrial experiments, methods and techniques of technical and economic, graphic-analytical, correlation analysis. Results. The regularities of the change in the value of least resistance line from the ultimate strength of the ore to uniaxial compression and the diameter of blast holes were established. The obtained regularities made it possible to develop a methodology for calculating the rational parameters of drilling and blasting operations using an emulsion explosive of the Ukrainit PP–2B type in the deep horizons of the Kryvbas mines. Dependences of the technical and economic indicators of the use of the emulsion explosive of the Ukrainit PP–2B type in ore breaking on mining-geological and mining-technical factors were established. On the basis of the established rational parameters of drilling and blasting operations, a variant of the technological scheme for breaking iron ores by using an emulsion explosive of the Ukrainit PP–2B type with loading of ascending fans of deep wells using a self-propelled charging module RTCh–23 was proposed and economically justified. Originality. Power-law dependences of the least resistance line on the ultimate strength of the ore for uniaxial compression and the diameter of blast holes were established when using an emulsion explosive of the Ukrainit PP-2B type. Practical value. The method is developed for calculating the parameters of drilling and blasting operations with using an emulsion explosive of the Ukrainit PP-2B type in the deep horizons of the Kryvbas mines. The economically justified version of the technological scheme for breaking off iron ores with using an emulsion explosive of the Ukrainit PP-2B type, which will make it possible to achieve an annual economic effect in the amount of UAH 11.9 million. Conclusions. It is established that the use of an emulsion explosive of the Ukrainit PP-2B type is a non-alternative direction in the further development of minerals at great depths, which will make it possible to reduce the cost of the technological process of breaking by 21% and reduce the harmful environmental impact on the world by 2,6–3,9 times.