Geology and Mining: Narrow-Width (Vein) Mining and the Geologist

SEG Discovery ◽  
2021 ◽  
pp. 25-36
Author(s):  
Adrian Pratt
Keyword(s):  
Rock Mass ◽  
Value Chain ◽  
Underground Mining ◽  
Mineral Exploration ◽  
Surrounding Rock ◽  
Early Career ◽  
Open Pit ◽  
Team Members ◽  
Narrow Width ◽  
Mine Development

Editor’s note: The Geology and Mining series, edited by Dan Wood and Jeffrey Hedenquist, is designed to introduce early-career professionals and students to a variety of topics in mineral exploration, development, and mining, in order to provide insight into the many ways in which geoscientists contribute to the mineral industry. Abstract Mining narrow deposits presents a discrete set of additional challenges to those common to most mining. Some challenges arise from the deposit’s width, its geometry—dip and planar continuity—and its interaction with the surrounding rock mass. The geology of the surrounding rock mass and associated physical properties of its geologic units and structures influence the application of mining method and mine design for both surface (open-pit) and underground mining. Successful mine development is the product of teamwork and depends on the collaboration, coordination, collective experience, and confidence of the team. Above all, it relies on relationships shared by the team members along the value chain. These relationships are extremely important, since miscommunication, misunderstandings, missing data, etc., can result either in lost opportunities to develop a better mine, or will load the project with unnecessary risk. This article is focused on underground mining of narrow-width deposits (veins) and the role of economic geologists in the definition and development of these deposits. The crucial importance of recognizing potential for value creation early in the life of a narrow-width mine project is highlighted, when an economic geologist is often a project’s key proponent. This role as the key proponent may change as a project progresses toward development, but early geologic contributions provide the foundation for narrow-width mine development.

Importance of Geology in Cave Mining

SEG Discovery ◽  
2019 ◽  
pp. 1-21
Author(s):  
Gideon Chitombo
Keyword(s):  
Underground Mining ◽  
Mineral Exploration ◽  
Low Cost ◽  
Early Career ◽  
Open Pit ◽  
Infrastructure Development ◽  
Mine Design ◽  
Discontinuous Surface ◽  
High Productivity ◽  
Heterogeneous Rock

Editor’s note: The Geology and Mining series, edited by Dan Wood and Jeffrey Hedenquist, is designed to introduce early-career professionals and students to a variety of topics in mineral exploration, development, and mining, in order to provide insight into the many ways in which geoscientists contribute to the mineral industry. Abstract Cave mining methods (generically referred to as block caving) are becoming the preferred mass underground mining options for large, regularly shaped mineral deposits that are too deep to mine by open pit. The depth at which caving is initiated has increased over the past few decades, and operational difficulties experienced in these new mines have indicated the need for a much improved geologic and geotechnical understanding of the rock mass, if the low-cost and high-productivity objectives of the method are to be maintained and the mines operated safely. Undercuts (the caving initiation level immediately above the ore extraction level) are now being developed at depths of >1,000 m below surface, with the objective of progressively deepening to 2,000 and, eventually, 3,000 m. Many of the deeper deposits now being mined by caving have lower average metal grades than previously caved at shallower depths and comprise harder and more heterogeneous rock masses, and some are located in higher-stress and higher-temperature environments. As a result, larger caving block heights are required for engineering reasons; mining costs (capital and operating) are also escalating. In these deeper cave mining environments, numerous hazards must be mitigated if safety, productivity, and profitability are not to be adversely affected. Fortunately, potential hazards can be indicated and evaluated during exploration, discovery, and deposit assessment, prior to mine design and planning. Major hazards include rock bursts, air blasts, discontinuous surface subsidence, and inrushes of fines. These hazards are present during all stages of the caving process, from cave establishment (tunnel and underground infrastructure development, drawbell opening, and undercutting) through cave propagation and cave breakthrough to surface, up to and including steady-state production. Improved geologic input into mine design and planning will facilitate recognition and management of these risks, mitigating their consequences.

Prediction of the Ground Vibration Rate during Large-scale Explosions in the Underground Conditions

2021 ◽  
pp. 41-45
Author(s):  
V.N. Tyupin ◽  
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Underground Mining ◽  
Calculated Data ◽  
Ground Vibration ◽  
Open Pit ◽  
Vibration Velocity ◽  
Earth Surface ◽  
Seismic Safety ◽  
The Earth

At present, to ensure seismic safety in massive explosions, the analytical dependence of the determination of the vibration velocity of M.A. Sadovsky rock mass is mainly used. This dependence is widely used in the creation of seismic-safe technologies for mineral deposits open-pit and underground mining. However, scientific research and production experience showed that the rate of oscillation depends on the energy parameters of the explosive, the diameter and length of its charges, the number of simultaneously exploded charges, the number of deceleration stages, the deceleration interval, etc. The purpose of this article is to predict the speed fluctuations of the massif on the earth surface when conducting the underground explosions depending on the parameters of large-scale explosions and physical-technical properties of the rock masses in the areas of explosion of the protected object. The formulas for calculating the velocity of rock mass on the earth surface during large-scale explosions in the underground conditions are substantiated and presented. The formulas were used for calculating the vibration velocities of the rock mass on the earth surface in accordance with the parameters of drilling and blasting operations during large-scale explosions in the mines of GK VostGOK. Comparison of theoretical (calculated) data and the results of actual measurements indicates their convergence. By changing the controlled parameters in the calculation formulas, it is possible to quantitatively reduce the seismic effect of a large-scale explosions on the protected objects. Further research will be aimed at studying the influence of tectonic faults, artificial contour crevices, filling massif or mined-out space on the rate of seismic-explosive vibrations during blasting operations in the mines. The research results can be used in the preparation of rules for conducting large-scale explosions at the underground mining.

Rock Mass Deformation Characteristics in High-Steep Slopes Influenced by Open-Pit to Underground Mining

2016 ◽  
Vol 34 (3) ◽  
pp. 847-866 ◽  
Author(s):  
Chuanbo Zhou ◽  
Shiwei Lu ◽  
Nan Jiang ◽  
Dingbang Zhang ◽  
Zhihua Zhang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Open Pit ◽  
Deformation Characteristics ◽  
Rock Mass Deformation ◽  
Steep Slopes ◽  
Mass Deformation

Study of the Rock Mass Failure Process and Mechanisms During the Transformation from Open-Pit to Underground Mining Based on Microseismic Monitoring

2018 ◽  
Vol 51 (5) ◽  
pp. 1473-1493 ◽  
Author(s):  
Yong Zhao ◽  
Tianhong Yang ◽  
Marco Bohnhoff ◽  
Penghai Zhang ◽  
Qinglei Yu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Failure Process ◽  
Microseismic Monitoring ◽  
Open Pit ◽  
Mass Failure ◽  
Rock Mass Failure

scholarly journals Two-Dimensional Modeling of the Influence of Underground Mining Direction on Slope Stability in Coordinated Open-Pit and Underground Mining

2021 ◽  
Author(s):  
Bowen Liu ◽  
Zhenwei Wang ◽  
Xinpin Ding ◽  
Zhitao Wang ◽  
Bin Li
Keyword(s):  
Rock Mass ◽  
Slope Stability ◽  
Underground Mining ◽  
Mining Area ◽  
Two Dimensions ◽  
Open Pit ◽  
Engineering Practice ◽  
Inverse Slope ◽  
Coal Wall ◽  
Mining Face

Abstract Under a background of coordinated open-pit and underground mining engineering practice in the Pingshuo mining area, a combination of numerical simulations and similar-model experiments was used to study the influence of the underground mining direction on slope deformation in two dimensions. The results show that the disturbance caused by inverse-slope mining is more obvious than that caused by along-slope mining. Underground mining presents an asymmetric influence on the open-pit slope; the slope rock mass on the open-off cut side is disturbed more than that on the coal-wall side. Compared with the slope in front of the advancing direction of the underground mining face, the degree of rock-mass damage and stress concentration of the slope of the open-off cut side are more serious. As such, in coordinated open-pit and underground mining practice, an along-slope mining direction is recommended to reduce adverse effects on slope stability and improve the recovery rate of coal resources.

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

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.

Geotechnical Engineering for Mass Mining

SEG Discovery ◽  
2020 ◽  
pp. 22-31
Author(s):  
Andre van As
Keyword(s):  
Rock Mass ◽  
Data Collection ◽  
Mineral Exploration ◽  
Early Career ◽  
Significant Shift ◽  
Mass Behavior ◽  
Geotechnical Monitoring ◽  
Increasing Demand ◽  
The Many ◽  
Geotechnical Model

Editor’s note: The Geology and Mining series, edited by Dan Wood and Jeffrey Hedenquist, is designed to introduce early-career professionals and students to a variety of topics in mineral exploration, development, and mining, in order to provide insight into the many ways in which geoscientists contribute to the mineral industry. Abstract The rock mass response to mining is governed by the rock mass characteristics and the mining-induced changes that drive its behavior. To be able to study and accurately predict the response of the rock mass to mining, it is imperative that both the orebody and the enclosing country rocks are well characterized through the collection and analysis of large quantities of good-quality, representative geologic, structural, geotechnical, and hydrogeological data. These are the fundamental constituents of a good geotechnical model whose reliability improves as the mining project matures and moves from exploration and study phases, passes the decision to develop, and proceeds into construction and then operations. Each phase provides greater exposure to the rock mass, reduces uncertainty, and increases reliability in the geotechnical model and in an understanding of the rock mass behavior. The quest of the geotechnical engineer is to understand the rock mass behavior and is no different from that of the geologist who defines the mineral resource, and it warrants (at the very least) the same level of rigor in data collection, analysis, and reporting. Just as the geologist continues to improve the orebody model through grade reconciliation during mining, so the geotechnical engineer must continually revisit and calibrate the geotechnical model during the operational phase of mining through geotechnical monitoring. The increasing demand by investors and stakeholders that the performance of a mine does not deviate from plan due to unforeseen geotechnical surprises warrants a significant shift in the level of geotechnical data collection, analyses, and rock mass monitoring through all stages of study and operations. This demand warrants supporting budgets and assurance processes that are commensurate with the complexity and extent of the geotechnical uncertainties.

scholarly journals A Model of Anisotropic Property of Seepage and Stress for Jointed Rock Mass

2013 ◽  
Vol 2013 ◽  
pp. 1-19 ◽  
Author(s):  
Pei-tao Wang ◽  
Tian-hong Yang ◽  
Tao Xu ◽  
Qing-lei Yu ◽  
Hong-lei Liu
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Underground Mining ◽  
Principal Direction ◽  
Water Pressure ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Metal Mine ◽  
Roadway Stability

Joints often have important effects on seepage and elastic properties of jointed rock mass and therefore on the rock slope stability. In the present paper, a model for discrete jointed network is established using contact-free measurement technique and geometrical statistic method. A coupled mathematical model for characterizing anisotropic permeability tensor and stress tensor was presented and finally introduced to a finite element model. A case study of roadway stability at the Heishan Metal Mine in Hebei Province, China, was performed to investigate the influence of joints orientation on the anisotropic properties of seepage and elasticity of the surrounding rock mass around roadways in underground mining. In this work, the influence of the principal direction of the mechanical properties of the rock mass on associated stress field, seepage field, and damage zone of the surrounding rock mass was numerically studied. The numerical simulations indicate that flow velocity, water pressure, and stress field are greatly dependent on the principal direction of joint planes. It is found that the principal direction of joints is the most important factor controlling the failure mode of the surrounding rock mass around roadways.

scholarly journals Macro-Micro Response Characteristics of Surrounding Rock and Overlying Strata towards the Transition from Open-Pit to Underground Mining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Xiaoshuang Li ◽  
Shun Yang ◽  
Yunmin Wang ◽  
Wen Nie ◽  
Zhifang Liu
Keyword(s):  
Stress Reduction ◽  
Underground Mining ◽  
Local Deformation ◽  
Linear Increase ◽  
Surrounding Rock ◽  
Open Pit ◽  
Measurement Technology ◽  
Pressure Relief ◽  
Important Relationship ◽  
Overlying Strata

The macro-micro mining response of the surrounding rock and overlying strata towards the transformation from open-pit to underground mining is examined in the present study, based on the engineering background of the Jinning phosphate mine (Yunnan Phosphate Chemical Group Co., Ltd.) via simulations involving similar materials, digital photographic measurement technology, and numerical simulation. The mining deformation of the surrounding rock underground, and of the overlying strata, is shown to develop in three stages, namely: (1) small and local deformation, (2) continuous linear increase, and (3) the violent nonlinear collapse of the entire system. The internal distribution of stress in the surrounding rock and adjacent overlying strata of the inclined mined-out area is complicated. The degrees of pressure increase and pressure relief have an important relationship with the size of the mining space. The pressure relief is more complete close to the mined area, and the stress reduction decreases with increasing distance. The cracks propagate in arc shapes and have a tendency to penetrate into the upper and lower ends of the stope. The size of the excavation space plays a key role in the generation, propagation, and penetration of the cracks. Due to the disturbance of the first mining level and the increase in excavation depth, the rate of damage to the surrounding and overlying rock increases in the second mining level. This process generates more cracks, which accelerate the instability of the surrounding rock and overlying strata.

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