Mine Design Research Articles

The modified Mathews–Potvin method in geotechnical substantiation of stope design with equivalent linear cross-sectional search

Mining technology design choices involve substantiation of safe geotechnical parameters including kinematic stability of exposed elements of mining systems, in particular, roofs and sidewalls of stopes. In Talnakh mines, extraction of impregnated ore follows high-grade ore mining, as a rule, which greatly affects the initial stress–strain behavior of rock mass. Impregnated ore is undermined, and the stoping area stability depends in many ways on the kinematic stability and block structure of rock mass rather than on its stress level. The kinematic stability undergoes influence of natural properties of rock mass in combination with geotechnical characteristics formed during mine design. The body of these factors defines the variety of combinations of input parameters, which needs a calculation approach in use to be partially automated. With this aim in view, the authors propose the calculation approach to the substantiation of stope designs in impregnated ore mining using the Mathews–Potvin stability assessment method and its modifications. The choice of this method is governed by its positive application in the global practice and by its scope encompassing all factors of influence on stability—the kinematics and structure. The method is usable as the discrete variant of stability estimation in the stability–transition state–failure system. The approach enables finding a balance between safety and efficiency in ore mining using stoping systems.

Investment Project Analysis Pit CACD Block 8 Using Discounted Cash Flow (DCF): A Case Study of Pt. Berau Coal

PT Berau Coal which is located in Berau Regency, East Kalimantan Province. Pit C2 Block 8 Binungan Mining Operation Area 2 PT Berau Coal is a coal mining operation area with multi-seam characteristics with a slope of coal seams at intervals of 40 – 60 degrees. The characteristics of coal deposits are one of the considerations in the formation of coal mining designs in collaboration with other disciplines, including geotechnical, hydrology, safety and environment, as well as other aspects. PT Berau Coal faces several challenges, risks and uncertainties such as fluctuations in coal prices, production capacity, mining costs and related legal aspects. Therefore, mining planning and strategy must be carried out carefully until PT Berau Coal's mining permit expires in 2025. Financial assessment must accommodate the risks and uncertainties that exist to overcome the weaknesses of the DCF method. The monte carlo symulation method serves as an alternative for creating dynamic quantitative models for mining projects. In this method, the discounted risk factor is applied directly to variables of uncertain sources, such as coal prices, to improve accuracy. Therefore, evaluating long-term mine planning at PT Berau Coal using scenario analysis and Monte Carlo simulation is useful for making better decisions in production, investment and resource allocation schemes. With the results of a financial evaluation of NPV DCF 38mio USD, NPV Monte Carlo 40mio USD, IRR 51%, PI 4.12, and PBP 2.28 years PT Berau Coal will consider and make a decision whether to continue the project considering several risks or cancel the investment and not continue mining in Pit CACD.

Numerical studies on heat extraction evaluation and multi-objective optimization of abandoned oil well patterns in intermittent operation mode

Geothermal is an important renewable energy source, but the high cost of drilling limits its popularization. The oilfield area is rich in geothermal resources and has a large number of high-temperature abandoned wells. It is an economic and effective method to transform the abandoned wells into geothermal wells. At present, the heat extraction research of abandoned wells mostly focuses on single-well closed systems, while the most common in oilfields is the well patterns open system, which involves the flow and heat extraction of oil-water multiphase. More, the main utilization mode of oilfield geothermal is heating, which is an intermittent operation, and the existence of the heat recovery period makes the solution process more complicated compared to continuous production. Therefore, the numerical simulation of oil-water two-phase and the scheme optimization under intermittent operation are the key problems in the current oilfields geothermal research, that is, it should be made clear what the effects of operation parameters are and how to get the optimization design for the intermittent mining of heat-oil cogeneration from abandoned wells. For this reason, the oil-water two-phase heat-flow coupling model and economic evaluation model are established. Then, database is established through parameter sensitivity analysis, and multi-objective optimization research is carried out on the lifetime and economic benefits using Non Sorting Genetic Algorithm II (NSGA-II). The results show that economic benefit and end-point temperature of the optimized scheme are enhanced by 6.75 million US dollars and 7.10 K after 15-year production, respectively. The heat-oil cogeneration performance is superior, so the influence of oil phase cannot be ignored in the heating process of the well patterns system for oilfield geothermal production.

Development and application of a borehole stress meter in rocks surrounding the roadway, based on optical-fiber sensing technology

Stress in rock masses is an important parameter in the design and construction of underground engineering, such as the design and maintenance of mine roadways and the design of mining working faces. It is also a fundamental force causing the deformation and failure of geotechnical engineering excavation. At present, the abutment-pressure monitoring technology of the surrounding rocks of the coal mine roadway in China is not intelligent and systematic and lacks some high-precision sensing instruments and multi-functional monitoring systems. The mechanical model of the rocks surrounding the borehole was constructed by theoretical analysis of problems in the stress monitoring technology for underground rock masses in coal mines. Additionally, the interaction between the surrounding rocks and the borehole stress meter was analyzed. The borehole stress meters for tubular-structure fiber Bragg grating (TS-FBG) and cystic-structure fiber Bragg grating (CS-FBG) were designed by combining the sensing principle and sensing characteristics of fiber Bragg grating, and the performance of the two kinds of fiber Bragg grating borehole stress meters was compared by laboratory test. The track roadway of the 14,301 tested working faces in the Shaqu Coal Mine was taken as an example, and the stress of the rocks surrounding the 14,301-track roadway was monitored in real time by CS-FBG borehole stress meter during the mining of the working face. The following conclusions are drawn from the field application. The rig-site utilization results revealed obvious stress growth and stress peak zones in the mining-stress change curves of each measuring point on the two sides of the 14,301-track roadway in the process of mining the tested working face. Additionally, there were four stages: rapid rise, uniform growth, rapid rise to the peak, and rapid decline. Maximum stress monitored by the second station was 18.5 MPa, and the influence range of stress was over 140 m. Maximum stress monitored by the first measuring station was 19 MPa, the influence range of stress was about 80 m, and the peak stress position was about 20 m in front of the coal wall. Rig-site utilization proved the design of the CS-FBG borehole stress meter to be reasonable. Performance was stable and reliable, and the successful operation of field monitoring achieved the expected effect.

Numerical study on spatial distribution of blast-induced damage zone in open-pit slope

The excavation damage zone in rock slopes after drill-and-blast operations is of great significance for assessing the slope stability and design of open pit mines. The traditional method simplifies, the spatial distribution of the damage zone in a slope following blasting is as a single radius distributed, which leads to an inaccurate evaluation of slope stability. Herein, a model coupling the tensile damage and the Drucker-Prager yield criteria is established to investigate the spatial distribution characteristics of blast-induced damage zone in the final wall of an open-pit. Explosive explosion is converted to an equivalent pressure time history acting on the blasthole wall and the extension of the damage observed in the field test is reproduced successfully by numerical simulation. The proposed model is verified on the basis of the site-monitored data from the Wushan Copper mine, a large-scale open-pit mine in Inner Mongolia, China. The results show that the damage decreases with increasing depth, exhibiting a nonlinear distribution behind the slope face. The maximum depth and scopes of horizontal and vertical damage occur at the slope crest. The proposed model is compared with five widely used damage models and proves to be more capable of representing the spatial distribution of the damage zone observed in the site test. Finally, the formation mechanism of the maximum damage depth along the crest is also revealed.

Large-scale storage of hydrogen in salt caverns for carbon footprint reduction

This article presents a geomechanical appraisal of green hydrogen (H2) storage in salt caverns opened by solution mining as a technical contribution to carbon footprint reduction. The location of the salt cavern is speculative, within possible limits to be found in the salt deposits in the Gulf of Mexico of the USA, as the aim is to demonstrate the technical feasibility of the concept. It presents the conceptual design of the wells used for the solution mining of the caverns and the operation cycle of injection and withdrawal of hydrogen. The contribution of the study presented stems from the methodology adopted in the simulation of the geomechanical structural behavior of the salt cavern and in its design for storing hydrogen, which has thermomechanical properties more complex than natural gas. The numerical simulation considers the nonlinear physical viscoelastic and elastoplastic phenomena, with different constitutive laws for representing the geomechanical behavior of geomaterials. The constitutive laws based on deformation mechanisms are used (multi-mechanisms of deformation – M.D.) to simulate the creep of the salt rock. The article also presents a protocol for sizing the caverns, considering more than 40 years of experience in the design of conventional and solution mining of rock salt. It presents the concept of admissible halite creep strain and safety factors necessary to establish a stress belt that avoids hydrogen leaks at all stages of cavern construction and hydrogen storage. Using this methodology, the authors found that the cavern studied (220 m in height and 95 m in diameter) can hold 11,968,000 kg of working hydrogen.

Dynamic optimization of open-pit coal mine production scheduling based on ARIMA and fuzzy structured element

A dynamic optimization method was created to address the production schedule issue in an open-pit coal mine while taking into account the characteristics of the fuzzy structured element. The fuzzy mining capacities of all “geologically optimal push-back bodies” were then examined using the moving cove method. One of the most crucial elements in the process of open-pit coal mine production scheduling optimization is coal pricing. As a result, this work also presents a dynamic optimization technique for production scheduling that incorporates the prediction of economic time series and the generation of dynamic economic indices. An appropriate time series model is created to forecast the future coal price based on previous data on coal prices. The prediction results are used in the calculation of optimal mining body generation to dynamically obtain the optimal production scheduling model. The Baorixile Open-pit Coal Mine in China’s Inner Mongolia Autonomous Region is using this method. The Autoregressive Integrated Moving Average Model ARIMA is constructed to anticipate the coal price in the future 23 years by evaluating and processing the coal price from 2009 to 2022, and the ideal production scheduling scheme of the mine economics is afterwards identified. The ideal fuzzy coal mining volume, the potential production life, and the fuzzy total net present value (NPV) of the annual production scheduling are all provided at the same time. The optimization findings can better give fundamental support for mine design and future production since the fuzzy problem is accurately expressed by correct formulations.

Modified Tributary Area and Pressure Arch Theories for Mine Pillar Stress Estimation in Mountainous Areas

This paper describes a parametric study using discrete element modeling (DEM) of partial mining in a mountain terrain with in situ pillars for overburden support. For room and pillar mining or strip pillar mining, the accurate estimation of pillar stress is essential to ensure pillar stability and mine safety. Classical mine design methods such as the tributary area theory (TAT) and the pressure arch theory (PAT) are commonly used to calculate the pillar stress for mines under a relatively flat terrain. However, mine sites with uneven terrains can result in nonuniform stress distributions in the mine system and the classical methods may underestimate the pillar stresses by several times. In this paper, 1200 DEM mine models with terrains that include either a single slope or a valley, have been constructed. Through rigorous numerical modeling, the effects of several design parameters are identified: The influence factors, influence range, and mechanism of the concentrated pillar stresses computed from the models indicate that the shape of an extended pressure arch (EPA) can dictate the accuracy of the TAT and PAT methods. Based on the EPA estimation, a pillar stress estimation method is proposed for the design of mines in mountainous terrains. This paper updated the method of terrain-induced pillar stress concentrations with an improved EPA theory, and the gap between PAT and TAT theories is addressed by further discussion on their relationship and applicability.

Study on Library Management System Based on Data Mining and Clustering Algorithm

In order to improve the information retrieval and resource sharing abilities of the library and establish an intelligent library information management system, alibrary management system based on data mining and clustering algorithm is proposed. The system development is divided into two modules: library mining algorithm design and information management system software development. Library data mining design and clustering algorithm of library management system development. System development is divided into two modules: library mining algorithm design and information management system software development. Big data fusion and feature clustering methods is used to design intelligent information retrieval algorithms in library information management to establish library management database. Realizing the development and design of library management system under embedded environment, and finally experimental test analysis is carried out. Results show that the use of the proposed method for library information management can improve the accuracy of book recommendation, which is 16.7% higher than traditional methods on average. It has good data mining, and has good performance indicators in data recall and precision. Therefore, this algorithm is not only a means of automated management of library systems, but also an effective means to realize library information modernization.

Evaluation of the overall effectiveness (OEE) of autonomous transportation system (AHS) equipment and its impact on mine design. Open pit mine case study

In recent years, the increasing demand for autonomous vehicles in the mining industry has led to a greater focus on integrating these solutions with mine design. As technology advances, mining companies are looking to maximize the benefits of automation in terms of efficiency, productivity, and safety. The adoption of autonomous vehicles in mine design allows for the optimization of planning and operation of mining activities. Autonomous equipment can work continuously, reducing downtime and improving resource utilization. This has a direct impact on the overall equipment effectiveness (OEE), as availability and performance are significantly enhanced.In this research, the overall equipment effectiveness (OEE) of an Autonomous Haulage System (AHS) and its impact on the design of an open-pit mine were evaluated at the engineering level in Chile. Additionally, a representative month of operation (January 2034) was modeled using discrete event simulation technique with current operation and AHS philosophies. The results of this model, which were validated and calibrated based on historical information, meetings with different work groups, and understanding of the engineering level of the study, indicate that the OEE of manual operation is 14.4% lower than that of AHS operation, demonstrating an opportunity for the implementation of this technology.

Izrada geotehničkog i hidrogeološkog modela sektora br. 6 flotacijskog jalovišta "Valja Fundata" u Majdanpeku

Geotechnical and hydrogeological investigations were carried out at the location on the sector 6 of the "Valja Fundata" flotation tailing dump in Majdanpek. The goal of investigations was to define the geotechnical and hydrogeological structure of this part of the tailings dump, as a basis for determining the optimal conditions for overhanging and rehabilitation of the terrain, planned for the landfill expansion. The appropriate geotechnical and hydrogeological terrain models, which will be used as a starting point for further construction and mining design, were developed applying the multidisciplinary geological investigation models.

Probabilistic characterization of correlation between two rock properties: a data-driven approach

Rock parameters are required during the design and stability analysis of mining and geotechnical structures. There is a correlation between some rock properties, especially those obtained from the same experimental set-up, and the proper estimation of such correlation is important for reliable mining engineering analysis. However, a limited quantity of rock property data often available for most mining project sites makes it difficult to estimate a reliable correlation between two rock properties. To overcome this challenge, a data-driven approach that is based on Bayesian framework is presented in this study. The approach utilizes limited data pairs of rock parameters from a site and characterizes the site-specific joint probability distribution of two correlated rock properties, without the use of an empirical model. Real data of rock properties obtained from uniaxial compression tests on migmatites at the Sanandaj-Sirjan zone in Iran is used to illustrate the approach. The results from the approach show that the marginal statistics, marginal and joint probability distributions, and correlation coefficient from the proposed approach are consistent with those of the measured data from the adopted site. This indicates that the approach is effective for characterizing the correlation between correlated rock properties and can be used when there is a need for such characterization at a site with limited data.

Geotechnical assessment of rock masses in metallic mineral deposits, a view on the “hidden” issues in open-pit design

Defining rock mass geotechnical properties is a critical step in the process of open-pit slope design. Geotechnical engineers assess the frequently highly altered rocks of metallic mineral deposits by applying standardized geotechnical classifications primarily developed for underground mining operations or design of civil structures such as tunnels and cut slopes. In some cases, the projects do not consider additional aspects of the rock masses, such as: zoning according to rock mass alteration schemes, prediction of blasting disturbance and weathering depth, rock strength loss over time, swelling effects, etc. Unfortunately, in some mineral deposits, many of these aspects appear to overlap, leading to difficulties in the process of open-pit design. In the case of neglecting such complex issues, there can be serious consequences in regard to future safe mine operation or even failure of slope/s. The paper presents findings from Macedonian legislation and literature overview on these aspects, regulations from other countries where available, as well as personal experiences of the authors. Some suggestions on the scope of geotechnical investigation works are briefly presented. It is considered that a more serious approach is needed in order to achieve a better understanding of the “long term” geotechnical behaviour of rock masses in such high risk environments.

Future of Mining and Geology: Increase in the Use of Cave Mining Methods to Extract Ore Over the Next 30 Years

Abstract The mining industry faces a period of increasingly difficult challenges over the next 30 years. The increasing demand for traditional mineral resources will likely continue unabated as developing countries modernize and the transition from fossil fuels to renewable energy sources ramps up. Compounding the challenge will be more rigorous constraints on mining imposed by environmental, social, and corporate governance (ESG) standards and regulations, as well as the progression from open-pit and shallow underground deposits to large, deeper, potentially lower-grade deposits, where underground mass mining methods are the only viable option. The latter change will especially apply to metals that are critical to mass electrification, including the traditionally required metals such as Cu, Ni, Co, Mn, Zn, U, etc. The more expensive-to-produce critical metals, such as Li, rare earths, high-purity alumina, etc., are currently only used in smaller quantities, and thus open-pit mining of these may remain viable until their near-surface resources are depleted. The large-scale mining of Cu, Ni, and Mo in particular will increasingly rely on cave mining methods, as these are the only profitable underground methods capable of yielding the large tonnages necessary to meet global demands, such as raising living standards within developing countries and providing the foundation for mass electrification of modern society, and all at a time when shallow deposits mined by open pit are becoming scarce. The application of cave mining is thus expected to increase in the future for deep mineral deposits with characteristics that are suited to this mining method. However, poor cave mine performance and/or unpredicted rock-mass responses (e.g., mine-induced seismicity) during cave mining can threaten the viability of the mine and will reduce investor confidence in this method. Irrespective of whether mining is of a traditional metal on a very large (mass) scale, or of a presently critical metal that now has lower tonnage requirements, we predict that geology will need to be more comprehensively considered during mine planning and design—right from the early stages of mine study—because of the uncertainties that the host rocks (geology) present to mining. This will be especially important in complying with the ESG constraints that are being applied to mining companies, in addition to the concept of sustainability that they also seek to address. We review—and propose remediation research of—the various geology-related issues that are already causing concern during mass underground mining by caving of Cu ore; some of these issues are equally applicable to other types of mining, such as open-pit and narrow-width extraction.

Longwall top coal fall index from an integrated numerical and statistical analysis

Assessment of top coal fall potential is of great importance for sustainable longwall caving mining. However, available assessment tools/indices for the fall are applicable to roof rock only, and their use for top coal (whose geological structures may be different) can be inappropriate. This paper presents a new index for top coal fall in longwall mining where the fall is controlled by the cantilever effect. The index is developed from an integrated numerical and statistical analysis using the database from Ha Lam coal mine in Vietnam. The numerical analysis reveals that the strength and stiffness of in-seam discrete fractures and coal’s elastic modulus are inversely proportional to top coal fall. Meanwhile, the density of discrete fractures and seam depth are found to be directly proportional to the fall. A procedure for the development of assessment equation for top coal is established using single and multiple regressions and model transformation technique. A new assessment index for longwall top coal fall named Fall Index (FI) is proposed, taking coal elastic modulus, fracture density, fracture friction angle, fracture stiffness and seam depth as input parameters. The study also reveals that statistically seam depth has the most significant effect while fracture density and fracture strength show the least significant effect on top coal fall. At the same time, coal’s elastic modulus and fracture stiffness play similar roles in the fall. The results from this paper assist engineers in better assessing top coal fall potential and subsequently better controlling longwall stability for various geological conditions in mine design.

Determination of sublevel stoping layout using a network flow algorithm and the MRMR classification system

Reduced access to shallow mineral resources, increased demand for minerals, and advances in technology have led to the development of deep underground mines. The location of the stopes and, finally, the determination of the mine layout is one of the problems in the design of any underground mine. In this study, a network flow algorithm was used to optimize the underground mine layout where sublevel stoping was chosen as the mining method. Due to the geomechanical constraints, the empirical Mining Rock Mass Rating classification system was used to determine the maximum stable width of the mineable stopes in the mine layout of each mining level. The model was run on a copper deposit and optimized for one mining level. The results obtained from running the model showed that 40 mineable stopes with a total recovery of 97% could be achieved. For validity check, the results were compared with those obtained from the algorithm of maximum value neighborhood. Application of the proposed model into the example block model revealed approximately 7% more economic value for the network flow algorithm than the maximum value neighborhood algorithm.

Block Caving Mining Method: Transformation and Its Potency in Indonesia

The block caving mining method has become increasingly popular in the last two decades. Meanwhile, Indonesia has several potential ore bodies which have not yet determined suitable mining methods. The references to block caving mining projects worldwide and the potency of metal deposits in Indonesia were reviewed to determine the requirements of ore bodies suitable for mining using the transformed block caving method. This method can be applied on a blocky ore body with a thickness of 200–800 m, various rock mass strengths until 300 MPa, from low to high (from 0.3% Cu until more than 1.0% Cu), but of uniform grade and at a depth from 500 to 2200 m. The technical specifications for running block caving mines have been synthesized, including preparation methods, undercutting strategy, mine design, mining equipment and monitoring. Considering the requirements and the successful practice of the block caving project in the Grasberg Caving Complex as a role model, the Indonesian government should concentrate on the detailed exploration of porphyry deposits and feasibility studies on applying the method to the prospective ore bodies, i.e., Onto, Tambulilato, Tumpangpitu and Randu Kuning. In addition, the exploration method, cost, operation, environment, mining policy and social geology are important aspects worth noting.

A Novel Approach to Integrating Uncertainty into a Push Re-Label Network Flow Algorithm for Pit Optimization

The standard optimization of open-pit mine design and production scheduling, which is impacted by a variety of factors, is an essential part of mining activities. The metal uncertainty, which is connected to supply uncertainty, is a crucial component in optimization. To address uncertainties regarding the economic value of mining blocks and the general problem of mine design optimization, a minimum-cut network flow algorithm is employed to give the optimal ultimate pit limits and pushback designs under uncertainty. A structure that is computationally effective and can manage the joint presentation and treatment of the economic values of mining blocks under various circumstances is created by the push re-label minimum-cut technique. In this study, the algorithm is put to the test using a copper deposit and shows similarities to other stochastic optimizers for mine planning that have already been created. Higher possibilities of reaching predicted production targets are created by the algorithm’s earlier selection of more certain blocks with blocks of high value. Results show that, in comparison to a conventional approach using the same algorithm, the cumulative metal output is larger when the uncertainty in the metal content is taken into consideration. There is also an additional 10% gain in net present value.

Cross-Modal Contrastive Hashing Retrieval for Infrared Video and EEG.

It is essential to estimate the sleep quality and diagnose the clinical stages in time and at home, because they are closely related to and important causes of chronic diseases and daily life dysfunctions. However, the existing "gold-standard" sensing machine for diagnosis (Polysomnography (PSG) with Electroencephalogram (EEG) measurements) is almost infeasible to deploy at home in a "ubiquitous" manner. In addition, it is costly to train clinicians for the diagnosis of sleep conditions. In this paper, we proposed a novel technical and systematic attempt to tackle the previous barriers: first, we proposed to monitor and sense the sleep conditions using the infrared (IR) camera videos synchronized with the EEG signal; second, we proposed a novel cross-modal retrieval system termed as Cross-modal Contrastive Hashing Retrieval (CCHR) to build the relationship between EEG and IR videos, retrieving the most relevant EEG signal given an infrared video. Specifically, the CCHR is novel in the following two perspectives. Firstly, to eliminate the large cross-modal semantic gap between EEG and IR data, we designed a novel joint cross-modal representation learning strategy using a memory-enhanced hard-negative mining design under the framework of contrastive learning. Secondly, as the sleep monitoring data are large-scale (8 h long for each subject), a novel contrastive hashing module is proposed to transform the joint cross-modal features to the discriminative binary hash codes, enabling the efficient storage and inference. Extensive experiments on our collected cross-modal sleep condition dataset validated that the proposed CCHR achieves superior performances compared with existing cross-modal hashing methods.

An improved pillar design methodology

Empirical pillar design methods are commonly used in the mining industry. The parameters within which these methods are valid are frequently unknown to the user or ignored. In addition, empirical design may not consider essential parameters such as blasting effects, orebody dip and the presence of geological structures, which all adversely affect the stability of the pillars. This can result in potentially serious pillar design strength over-estimates. Although the commonly based tributary area method is generally conservative, as the spans are seldom that large relative to the depth, failing to consider other relevant parameters can result in errors. Problems associated with an under-designed pillar can range from a local pillar collapse to a catastrophic chain reaction collapse (or run). Over-designed pillars are generally safe but reduce the extraction of the orebody, thus adversely affecting the profitability of the mining operation. We used laboratory tests and numerical modelling to understand the effects of pillar orientation, blasting and the presence of discontinuities on pillar strength. Reduction factors were developed with these models to be implemented in conjunction with the existing empirical pillar design methods. For any pillar or mine design, once it is implemented, the actual performance of the system must be checked regularly by observation and monitoring and adjusted if needed. The pillar design approach outlined in this paper can better optimize the pillar mining method by considering other generally ignored but important parameters, thus improving safety, productivity, and economic aspects.