Numerical modeling of open pit (OP) to underground (UG) transition in coal mining

Abstract The primary objective of the present paper is an attempt at evaluating the influence of sub-level caving operations on the slope stability of a still-functioning open pit coal mine in Vietnam. Initially, various methods of predicting the impact of underground mining on surface stability are discussed. Those theoretical considerations were later utilized in the process of constructing a Flac-2D-software-based numerical model for calculating the influence of underground operation on the deformation and possible loss of stability of an open pit slope. The numerical analysis proved that the values of open pit slope displacements were affected mainly by underground exploitation depth, direction of operation (i.e., from one slope to the other) and the distance from the slope plane. Real geomechanical strata parameters from the Vietnamese coal basin of Cam Pha were used in the modeling process. The paper is, therefore, a critical review of the hitherto proposed methods of predicting the impact of underground operation (UG) on open pit mining (OP), illustrated with selected examples of case studies on OP-UG interaction, followed by an original experiment based on numerical modeling method. This is first such study for the genuine conditions of the coal mining in Vietnam. The obtained results, however, should not be generalized due to a highly specific character of the analyzed phenomenon of mining-induced surface deformation. The practical implications of the study may occur extremely useful in the case of an UG-OP transition. Such a transition is often necessary for both technical and economical reasons, as in some coal basins open pit operations at greater depths occur unfeasible, which calls for a proper selection of parameters for a planned underground operation.

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Determination of the Ultimate Underground Mining Depth considering the Effect of Granular Rock and the Range of Surface Caving

Mathematical Problems in Engineering ◽

10.1155/2021/5576786 ◽

2021 ◽

Vol 2021 ◽

pp. 1-16

Author(s):

Rongxing He ◽

Jing Zhang ◽

Yang Liu ◽

Delin Song ◽

Fengyu Ren

Keyword(s):

Numerical Simulation ◽

Rock Mass ◽

Mechanical Model ◽

Surface Deformation ◽

Underground Mining ◽

Mining Area ◽

Open Pit ◽

Open Pit Mining ◽

Mining Depth

Continuous mining of metal deposits leads the overlying strata to move, deform, and collapse, which is particularly obvious when open-pit mining and underground mining are adjacent. Once the mining depth of the adjacent open-pit lags severely behind the underground, the ultimate underground mining depth needs to be studied before the surface deformation extends to the open-pit mining area. The numerical simulation and the mechanical model are applied to research the ultimate underground mining depth of the southeast mining area in the Gongchangling Iron mine. In the numerical simulation, the effect of granular rock is considered and the granular rock in the collapse pit is simplified as the degraded rock mass. The ultimate underground mining depth can be obtained by the values of the indicators of surface movement and deformation. In the mechanical model, the modified mechanical model for the progressive hanging wall caving is established based on Hoke’s conclusion, which considers the lateral pressure of the granular rock. Using the limiting equilibrium analysis, the relationship of the ultimate underground mining depth and the range of surface caving can be derived. The results show that the ultimate underground mining depth obtained by the numerical simulation is greater than the theoretical calculation of the modified mechanical model. The reason for this difference may be related to the assumption of the granular rock in the numerical simulation, which increases the resistance of granular rock to the deformation of rock mass. Therefore, the ultimate underground mining depth obtained by the theoretical calculation is suggested. Meanwhile, the surface displacement monitoring is implemented to verify the reasonability of the ultimate underground mining depth. Monitoring results show that the indicators of surface deformation are below the critical value of dangerous movement when the underground is mined to the ultimate mining depth. The practice proves that the determination of the ultimate underground mining depth in this work can ensure the safety of the open-pit and underground synergetic mining.

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Combined Method of Coal Mining in the Opening of Shallow Layers as a Direction of Innovative Development of Geotechnology

E3S Web of Conferences ◽

10.1051/e3sconf/202131501006 ◽

2021 ◽

Vol 315 ◽

pp. 01006

Author(s):

Tatiana Tyuleneva ◽

Roman Shishkov ◽

Elena Kucherova ◽

Marat Moldazhanov

Keyword(s):

Coal Mining ◽

Underground Mining ◽

Methodological Approach ◽

Production Capacity ◽

Open Pit ◽

Open Pit Mining ◽

Mining Operations ◽

Balanced Development ◽

Coal Reserves ◽

The Cost

In recent years, there has been a decline in the efficiency of coal mining by traditional methods. On the one hand, the volume of coal outside the contour of the cut, which is economically impractical for open-pit mining, is increasing. On the other hand, when using underground geotechnology, the cost of production exceeds the cost of performing mining operations using open geotechnology, this is due to differences in the factors of operation of the open pit and the mine. This circumstance determines the use of open-underground technology for mining coal reserves outside the contour of the open pit as an actual and promising direction. This article describes a methodological approach based on the use of technological schemes for the preparation and treatment of reserves of powerful shallow coal seams, the justification of the parameters of combined geotechnology with a coordinated and balanced development of open and open-underground mining operations with the distribution of reserves for open and open-underground mining of coal reserves beyond the limit contour of the open pit, the preparation of excavation sites directly from its workings and the coordination of production capacity and the speed of their development. Its application will increase the production capacity of the coal mining complex without additional environmental burden and will provide an increased return on investment.

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Assessment of reserves of innovative development of a coal-mining production association and the impact of organizational and economic relations on their use

News of the Ural State Mining University ◽

10.21440/2307-2091-2020-1-208-217 ◽

2020 ◽

Vol 1 (1) ◽

pp. 208-217

Author(s):

Andrey Sergeevich KOSTAREV ◽

Keyword(s):

Statistical Analysis ◽

Coal Mining ◽

Production Association ◽

Open Pit ◽

Open Pit Mining ◽

Innovative Development ◽

Production Potential ◽

Technological Support ◽

Economic Relations ◽

The Impact

Relevance. Within a market economy, some factors are constantly changing that affect prices, demand, supply, and the competitive environment, which greatly complicates the assessment and forecasting of development opportunities. At the same time, when formulating a strategy for innovative development and implementing the goals of an enterprise, it is impossible to do without reserves determination that can become a source of resource allocation for increasing the social attractiveness and competitiveness of an enterprise. Purpose of the study: to assess the reserves of innovative development of the coal-mining production association and to identify the impact of organizational and economic relations on their use. Methods of the study. In the course of the study, systemic and process approaches were used. To assess the reserves of innovative development, methods of comparison, timing observations, benchmarking, and statistical analysis were used. The dependence of the efficiency of using the production potential of a coal-mining production association on organizational and economic relations was formed using expert estimates, mathematical modeling, and statistical analysis. Results and practical relevance of the research. A system of indicators is proposed for assessing the reserves of innovative development of a coal-mining production association, including the coefficient of adaptation reserves (reflecting the possibility of increasing the efficiency of using the production potential of the association) and the progressiveness of technical and technological support (reflecting the growth reserves due to changes in technical and technological support). The application of the proposed indicators made it possible to establish that the efficiency of using the existing potential can be increased 1.39–1.52 times for various processes at the SUEK open-pit mining enterprises. Growth reserves, due to the possibilities of new technical and technological support of transportation excavation processes, amounted to 1.85 times relative to the achieved level. Conclusions. Organizational and economic relations are a relevant factor in the efficiency of using the production potential of a coal-mining production association, and their influence is described by a power-law increasing function. The revealed dependence makes it possible to increase the validity of choosing the most beneficial strategy for innovative development of a coal-mining production association from the perspective of stakeholders for realizing significant reserves and achieving the required efficiency of using its potential.

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INSAR COLLABORATIVE MONITORING MODE AND MULTI-MODE COMPUTING SERVICES FOR GEOHAZARDS IDENTIFICATION IN OPEN-PIT MINING AREA

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xliii-b1-2021-241-2021 ◽

2021 ◽

Vol XLIII-B1-2021 ◽

pp. 241-247

Author(s):

J. Zhang

Keyword(s):

Time Series ◽

Surface Deformation ◽

Underground Mining ◽

Mining Area ◽

Deformation Monitoring ◽

High Density ◽

Open Pit ◽

Open Pit Mining ◽

Mining Areas ◽

Wide Range

Abstract. InSAR has developed a variety of methods, such as D-InSAR, PS-InSAR, MBAS, CT, SqueeSAR, POT, etc., which have been widely used in land subsidence monitoring. For open pit mining areas, there are usually mining activity, complex terrain features, low coherence, and local large deformation gradients, which makes it difficult for time series InSAR technology to obtain high-density surface deformation information in open pit mining areas. Traditional methods usually only monitor the linear deformation of the surface caused by the mining of a few working zone above the underground mining area, and the temporal and spatial resolution is lower. How to obtain high-precision, high-density, and time-sensitive deformation information is the main difficulty of InSAR monitoring in open pit mining areas. Make full use of the geosensor network monitoring system, optimize monitoring mode of collaborated satellite-to-ground based InSAR, further realize whole calculation and geographic information services, to achieve early identification and discovery of abnormal in large-area macro-monitoring, and accurate monitoring of local areas in real-time early warning, which is the development direction of ground deformation monitoring of mining areas. The study area is Pingshuo open pit mining area. we fully study the application mode and services of InSAR monitoring for geohazards in open-pit mining area, through the establishment of satellite InSAR technology system for large-scale macro-monitoring and forecasting, and GBSAR and GSN for local precision monitoring. The effective mode of InSAR monitoring of geohazard in open-pit mines is summarized. A combination of D-InSAR, POT (Pixel offset tracking), Time Series-InSAR and GB-SAR is used in a wide range, and high-resolution optical images are used to identify localized changes in subsidence areas and open-pit mining areas.

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Productivity Analysis of Raisebore RB-50X for Raise Slot Drilling at Extraction level GBC PT. Freeport Indonesia

Journal of Earth and Marine Technology (JEMT) ◽

10.31284/j.jemt.2021.v2i1.2169 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

R J Kakisina ◽

Yudho Dwi Galih Cahyono

Keyword(s):

Underground Mining ◽

Open Pit ◽

Open Pit Mining ◽

Drilling Process ◽

Productivity Analysis ◽

Free Face ◽

Development Cycle ◽

Secondary Support ◽

Main Support ◽

The Impact

PT Freeport Indonesia is the largest gold and copper mine in Indonesia, located in Mimika Regency, Papua Province. In its operation, PT. Freeport Indonesia applies two mining systems, namely open pit mining and underground mining. Underground Mine at PT. Freeport Indonesia consists of DOZ, Big Gosan, DMLZ, Kucing Liar, and GBC, with one of the methods applied by PT. Freeport Indonesia is a block caving method. The Grasberg Block Cave mine has entered the production stage since September 2018, but in its operation the GBC Mine is still developing its operational area to meet production targets (development). The development cycle (cycle development), which is the main operation carried out, namely drilling and blasting, loading & transporting (mucking & hauling), primary support, and secondary support. To support the main operations, it is necessary to have main support consisting of access and area, ventilation, water and water, electricity, pull of tests, surveys, and dewatering. In the blasting process at the drawbell, one free face is needed which functions as the direction of rock collapsing in the blasting process on the drawbell. Making free face or commonly known as slot raise using a rasiebore machine from PT. Redpath for slot raise drilling. Meanwhile, in the drilling stage, the slot raise has a problem that has resulted in delays in the drilling process for the RB-50X raisebore tool. The impact of the delay in making the slot raise resulted in not achieving the production target due to a delay in the blasting process, where the blasting process in the drawbell area functions to break the rock so that it falls and can be transported to the crusher to enter the rock sizing process.

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Development Status of Coal Mining in China

10.21203/rs.3.rs-154477/v1 ◽

2021 ◽

Author(s):

liu xinjie ◽

Li Lianghui ◽

Yang yingming

Keyword(s):

Coal Mining ◽

Underground Mining ◽

Coal Mines ◽

Production Capacity ◽

Coal Industry ◽

Open Pit ◽

Open Pit Mining ◽

Development Status ◽

Average Production ◽

Speed Up

Abstract As a controllable active resource in China, coal mining is facing the transition from output to quality. Base d on the total mining production and average capacity, the current situation and level of coal mining at three scales of mine, city and province is analyzed , data support for the layout of sustainable mining development and the optimization of output is provided. The results show that China's coal is mainly mined by underground mining, accounting for 87%, with an average production capacity of 0.93 million tons. Open pit mining accounts for 13%, with an average production capacity of 5.73 million ton s. S o t he average production capacity of open pit and underground workers is 1.045 million tons, with 1,181 coal mines capacity lower than 0.3 million tons, accounting for 35% of the total coal mines, contributing only 4% to their output. They are distributed in about 48 cities in 6 provinces, seriously restricting the green coal mining. The coal industry should speed up the reduction of small coal mines in key provinces and cities, eliminate outdated product ion capacity in the central region, increase the speed and proportion of coal resources moving westward, and promote high quality development of coal mining.

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Managing and Reforesting Degraded Post-Mining Landscape in Indonesia: A Review

Land ◽

10.3390/land10060658 ◽

2021 ◽

Vol 10 (6) ◽

pp. 658

Author(s):

Pratiwi ◽

Budi H. Narendra ◽

Chairil A. Siregar ◽

Maman Turjaman ◽

Asep Hidayat ◽

...

Keyword(s):

Acid Mine Drainage ◽

Success Rate ◽

Coal Mining ◽

Best Management Practices ◽

Mine Drainage ◽

Forest Area ◽

Tree Planting ◽

Open Pit ◽

Open Pit Mining ◽

Acid Mine

Tropical forests are among the most diverse ecosystems in the world, completed by huge biodiversity. An expansion in natural resource extraction through open-pit mining activities leads to increasing land and tropical forest degradation. Proper science-based practices are needed as an effort to reclaim their function. This paper summarizes the existing practice of coal mining, covering the regulatory aspects and their reclamation obligations, the practices of coal mining from various sites with different land characteristics, and the reclamation efforts of the post-mining landscapes in Indonesia. The regulations issued accommodate the difference between mining land inside the forest area and outside the forest area, especially in the aspect of the permit authority and in evaluating the success rate of reclamation. In coal-mining practices, this paper describes starting from land clearing activities and followed by storing soil layers and overburden materials. In this step, proper handling of potentially acid-forming materials is crucial to prevent acid mine drainage. At the reclamation stage, this paper sequentially presents research results and the field applications in rearranging the overburden and soil materials, controlling acid mine drainage and erosion, and managing the drainage system, settling ponds, and pit lakes. Many efforts to reclaim post-coal-mining lands and their success rate have been reported and highlighted. Several success stories describe that post-coal-mining lands can be returned to forests that provide ecosystem services and goods. A set of science-based best management practices for post-coal-mine reforestation is needed to develop to promote the success of forest reclamation and restoration in post-coal-mining lands through the planting of high-value hardwood trees, increasing trees’ survival rates and growth, and accelerating the establishment of forest habitat through the application of proper tree planting technique. The monitoring and evaluation aspect is also crucial, as corrective action may be taken considering the different success rates for different site characteristics.

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