Search Documents

By W. A. Hustrulid

Introduction A problem that has faced mining engineers and mining geologists for many years is how to best explore a particular prospect so that the basic decision as to whether the material present is ore or only high-grade rock can be made with some confidence. It is obvious that one could not begin a large scale mining program on the basis of tests made on a few hand samples. On the other hand, one could not be 100 percent certain as to the average grade or tonnage before beginning development, as this would require the orebody to be mined out in the sampling process. The basic objectives of the exploration program can be stated as (1) to reduce mining risk; (2) to lessen the cost of development; and (3) to increase the profits of mining. The exploration program should be terminated when these objectives are no longer being met. The construction of tunnels is a specific mining operation. In the exploration program one should gather the data needed to determine (1) the type of excavation technique(s) to be used; and (2) the rate of advance that might be expected. As in the evaluation of an orebody, with the data collected it should be possible to estimate mining costs and project life. Unfortunately, at the present time, it is not possible to do this at least when dealing with medium to hard rock types. The reason for this, it is felt, is basically the inability to identify what specific rock mass properties are of use in tunnel design and to specify how these may be obtained in an exploration program. In short, the exploration program should be designed to give information regarding both the volume (length) and 'grade' (in

Jan 1, 1997

By Behdeen Oraee-Mirzamani

Tunnel stability has an important role in the production process of an underground coal mine. There are various methods for analysing tunnel stability, such as numerical methods and analytical methods. In this paper, numerical methods (Phase2 software) have been used to determine tunnel wall displacement in a mining tunnel of the Parvade underground coal mine. The Ground Reaction Curve has also been drawn using analytical methods to determine tunnel wall displacement. The comparison of results from the numerical method and the analytical method show a noteworthy difference in the tunnel wall displacement. The displacement calculated by the numerical method shows a lower value than that of the analytical method because the numerical method is more suited to modeling the various coal and rock layers, as well as the shape of the excavations found in coal mines. The methodology used in this paper together with the results obtained from both methods can serve as useful tools for the coal mine design engineer when determining the ground support requirements.

Jan 1, 2013

By Z. T. Bieniawski

Results of in situ investigations are discussed providing comparisons of rock mass deformability measurements by three methods: 'petite sismique' technique, the Goodman borehole jack and flat jacks. The tests were performed in exploratory tunnels constructed for site characterization purposes of an underground hydro-electric scheme. Due to the large number of data (41 petite sismique measurements, 45 Goodman jack tests and 19 flat jack measurements), it was possible to evaluate thoroughly the testing techniques employed. The purpose of this paper is to indicate the problems encountered in the interpretation of the results and to offer suggestions for selecting in situ tests. INTRODUCTION In situ tests are expensive and time consuming but they are an important aid in tunneling applications since they can provide deformability data of rock masses in contrast to rock material characteristics obtainable from small laboratory specimens. Some in situ tests are relatively easy to perform but their reliability may be in question unless a comparison of the data obtained by several different test methods is possible. Although many in situ techniques are available for determination of rock mass deformability (1), those more convenient to use are the Goodman jack, flat jacks and 'petite sismique. These methods are considered convenient because the Goodman jack is a borehole device; flat jacks can provide not only deformability data but also information about the stress field around excavations; while 'petite sismique' is based on seismic refraction surveys. Accordingly, these three methods have been selected for comparison.

Jan 1, 1979

By R. J. McLaughlin

Acid mine drainage (AMD) can occur as a natural phenomenon through oxidation of sulfide minerals. Oxidation by air and water can be exacerbated by mining. Because AMD can exhibit low pH, it is capable of extracting heavy metals from mineral deposits. The result is highly acidic drainage with elevated heavy metal concentrations -the combination of which can cause extensive environmental damage. Because of the importance of these factors, this paper is focused on sulfate based AMD. Due to widespread mining, the occurrence of AMD is ubiquitous. As a result, several approaches to treatment have been developed. Chemical treatment using alkali is most commonly employed to treat AMD. There are alternative methods of treatment, as well as alternative ways of handling treatment sludges or concentrates. Dewatering of sludge or concentrates is beyond the scope of this paper.

Jan 1, 1996

By P Hagan, S Wang, D Li, B Loh

A study was undertaken to quantify the differences in performance between a full-length encapsulated cable bolt and a partially encapsulated cable bolt. Much research has been reported on the differences in cable bolt design and operational parameters such as borehole diameter and grout type with much of this based on the Laboratory Short Encapsulation Pull Test (LSEPT). However, there is a gap in knowledge surrounding the effect of anchorage length on load transfer and cable bolt performance particularly with respect to the role of the bulb in modified cable bolt designs. The objective of this study was to expand the existing knowledge base of cable bolt performance with the intent of developing a revised design criterion. Alongside a comprehensive review of current cable support theory, design and practice, a series of pull tests was undertaken to compare each anchorage method using a high capacity modified cable bolt. The results serve to confirm earlier work on fully encapsulated anchorage. Both the peak load capacity and stiffness of the fully encapsulated cable bolt were nearly double that of the partially anchored cable bolt. When the tests were repeated in an oversized borehole, while there tended to be more variation in performance, there was little significant difference in the mean results. In addition to anchorage length, there are other factors that contribute to cable bolt performance including in order of sensitivity: embedment length, water-to-cement ratio of the grout, type of grout and borehole diameter. CITATION:Loh, B, Hagan, P, Li, D and Wang, S, 2018. A comparison of the performance of fully versus partially encapsulated cable bolts based on laboratory-scale testing, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 291–302 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By L. Adler

A systematic, balanced and inclusive formulation of the vast input data for mine design is presented. Since the quality of this statement severely influences subsquent design it is extremely important to senior mining engineers and the profession-at-large. If unfocussed, chaos can result along with serious ommisions. The basic categories, each a traditional one are: 1) Natural Conditions (geology and geography), 2) Company Capabilities (monetary and managerial), 3) Public Domain (regulations, contracts, good will, etc.) and 4) State of Art (mining engineering professionalism). To further reduce the data additional organizing principles were used: the distinctions of mining (vs. civil) engineering, proceeding from the general to particular, the basic engineering dimensions, and separating dependent from independent variables. The results are a unique and unified corpus, which anticipates the mine design procedure.

Jan 1, 1987

By Pertti Koukkari, Nagendra Tripathi, Karri Penttilä, Justin Salminen

A computational fluid dynamic model for a novel flash ironmaking process based on the direct gaseous reduction of iron oxide concentrates is presented. The model solves the threedimensional governing equations including both gas-phase and gas-solid reaction kinetics. The turbulence-chemistry interaction in the gas-phase is modeled by the eddy dissipation concept incorporating chemical kinetics. The particle cloud model is used to track the particle phase in a Lagrangian framework. A nucleation and growth kinetics rate expression is adopted to calculate the reduction rate of magnetite concentrate particles. Benchmark experiments reported in the literature for a nonreacting swirling gas jet and a nonpremixed hydrogen jet flame were simulated for validation. The model predictions showed good agreement with measurements in terms of gas velocity, gas temperature and species concentrations. The relevance of the computational model for the analysis of a bench reactor operation and the design of an industrialpilot plant is discussed.

Jan 1, 2014

By Frank T. Wheby, Edward M. Cikanek

A computer performs all logic and computations customarily done by hand in preparation of engineers' estimates or contractors' bids on tunnel-shaft systems. The program described is based on construction methods, work forces and equipment selections corresponding to the current state-of-the-art of rock, soft ground and cut-and-cover tunneling. The program contains logic to permit estimates of cost of complicated tunnel-shaft systems; it is not necessary to input quantities, as the program calculates those from the tunnel design that is internally generated. In any estimate, the program bases its cost computation on user-input requirements and site conditions, such as tunnel shape and size, shaft depth, ground characteristics, construction methods, and other factors. To provide great flexibility, the user of the program is provided with options for accepting designs built into the program or overriding these designs by his own inputs. An illustrative example is presented.

Jan 1, 1974

By F. Calizaya

This paper explains and discusses a computer program developed to determine the ventilation design parameters for complex auxiliary ventilation systems such as those found in the construction of long excavations with multiple headings. The program is based on the principle of partitioning the system into segments of finite length, and formulating and solving the resulting networks recursively. The application of the program is illustrated by the detailed solution of an auxiliary ventilation system proposed for the Exploratory Studies Facility (ESF) at the Yucca Mountain project, Nevada.

Jan 1, 1994

By Richard D. Zigmond

In this paper, a computer program that has been developed for determining the capital and operating costs for coal preparation plants is described along with its applications. The logic of the computer program is based upon the results of a survey of existing preparation plants, operators, plant contractors, equipment manufacturers, and consulting firms. This survey provided information on plant performance, order-of-magnitude costs, and costing procedures. Additionally, an extensive cost data file for the major capital equipment in coal preparation plants has been developed. Using the washability data and the computer program outputs, the cleaning costs per million Btu can be calculated. Details about the program and its applications can be found in a report by the authors (Zigmond et al., 1979).

Jan 1, 1981

By Jan M. Mutmansky

Simulation is a general term which commonly appears in the technical literature and which can have different meanings to different people. One interesting definition (9)* applicable in an engineering context is the following: "Simulation is the use of a model to study a problem." In most cases, the model referred to in the above definition is a simulation model constructed in a computer language and implemented on a computer in order to solve the problem under consideration. The application of computer simulation models to the study of problems in materials handling and earthmoving has been successful in the past. Generally speaking, this method has been used where the system to be studied has many variables and where the ability to predict the outcome of the system under different sets of conditions is difficult. The prime reason for using such a model is to evaluate the numerous likely ways of operating any particular system without the necessity of actually conducting full-scale field tests. The simulation model presented here is such an application made to the process of tunneling and, in particular, to the process of tunneling with a boring-type tunneling device. At first glance, the process of tunneling may not appear to be particularly complex and susceptible to study by a computer model. However, a close analysis of the tunneling process will reveal that it is rather complicated as a result of limitations placed upon the system by restricted space in the tunnel, geologic variations along the tunnel

Jan 1, 1972

By D. Nardini

The need to move towards faster and safer mine development is a key priority in mining houses globally. In addition to this, South Africa faces an array of challenges introduced by labour-intensive operations; hence a study was conducted to look into improving development rates and labour productivity, specifically in the areas where trackbound flat-end development is required. The aim of the study was to propose a method to deliver fit-for-purpose tracked tunnels that advanced at a rate of one blast per end every single working day. A major part of the study was to optimize the selection of an appropriate trackless fleet and mitigate any constraints introduced with the mechanization. This was done by creating scenarios, based on a typical case study, looking into the aspects around safety, mine design, mine activity cycling, men and machine requirements, service installations, and trackless-trackbound interfaces. The case study was based on a deep-level gold mine developing twin headings with connectings; however, with the move to extend and deepen platinum operations it is foreseen that twin end development will become more prevalent due to ventilation, logistical, and other requirements. With the introduction of the trackless mechanized system suggested, development rates of 56 m of system advance are expected (189 m total development), with on an average of three headings and fixed blast times. Scenarios run with multi-blast conditions yield expectations of 75 m/month advance of the system, significantly higher than the conventional performance seen today.

Jan 1, 2012

By Charles D. Litton

This report describes a smoke particle detector which utilizes a novel three electrode configuration and 5.0 [] source of Americium 241. The detector operates on the principle of diffusional charging by a region of unipolar molecular ions. The detector is sensitive to particle concentrations in the range of 10 to 5 20 ug/m3. The detector is intended for use primarily as an early warning fire detector but has the potential for other applications of particulate monitoring. In particular, this report adresses the potential use of the detector for monitoring diesel particulate matter (DPM). To assess the viability of this application, particle size data obtained from in-mine sampling of both DPM and dust were used to derive detector sensitivity functions for DPM and dust as a function of their mass concentrations only. These sensitivity functions are dependent upon the average diameters and size distributions of the DPM and dust. Using the derived sensitivity function for DPM, experiments were conducted in a ventilated tunnel where the true DPM mass concentrations, measured using a Tapered Element Oscillating Microbalance (TEOM) were compared to the mass concentrations calculated using the detector sensitivity function. The agreement between the two measurements was good, indicating that with additional experiments, coupled with in-mine evaluation of the detector, refinement of the device for use as a continuous monitor for DPM appears feasible.

Jan 1, 1989

By L Nienaber

Mines, after becoming operational, often retain the same support and reinforcement designs developed in the feasibility study. These designs are conceived from limited drilling data and regional experience, thus having an empirical flavour. Empirical designs are perceived to be conservative, catering for a variety of failure mechanisms, which are not always present in mine development drives.This begs the question: If you were to invest in the necessary resources to obtain sufficient data and complete the required analyses for the different development drives in the mine, to engineer a support and reinforcement scheme with the capacity to match the demand of the rock mass, what is the difference in cost when comparing an empirical design to an engineered design?To answer this question, mine tunnels with different geometries and orientations, where detailed structural data was available, were selected for a comparative design exercise. Material cost, development cost, cycle time and professional fees for engineered and empirical designs were estimated. The outcome is summarised in the following paper that discusses the process followed and the results of the design comparison.

Mar 8, 2011

By M. Z. Emad, A. Hassan, M. A. Raza, M. U. Khan, S. A. Saki

Digital modelling of a surface is crucial for Earth science and mining applications for many reasons. These days, high-tech digital representations are used to produce a high-fidelity topographic surface in the form of a digital terrain model (DTM). DTMs are created from 2D data-points collected by a variety of techniques such as traditional ground surveying, image processing, LiDAR, radar, and global positioning systems. At the points for which data is not available, the heights need to be interpolated or extrapolated from the points with measured elevations. There are several interpolation/extrapolation techniques available, which may be categorized based on criteria such as area size, accuracy or exactness of the surface, smoothness, continuity, and preciseness. In this paper we examine these DTM production methods and highlight their distinctive characteristics. Real data from a mine site is used, as a case study, to create DTMs using various interpolation techniques in Surfer® software. The significant variation in the resulting DTMs demonstrates that developing a DTM is not straightforward and it is important to choose the method carefully because the outcomes depend on the interpolation techniques used. In mining instances, where volume estimations are based on the produced DTM, this can have a significant impact. For our data-set, the natural neighbour interpolation method made the best predictions (R2 = 0.969, β = 0.98, P < 0.0001).

Feb 6, 2023

By Nicole Peter

When introducing digital training technology a practical approach helps address cultural concerns.  Solutions to help create acceptance are discussed.  Resistance to change may be deeply rooted in traditional mine training personnel.  Traditional training staff members may consider themselves less digitally-savvy and resist technological methods available to them. A transitional approach intended to help mitigate or resolve resistance is presented as a continuous improvement pathway toward full adoption.  This presentation contends every mine should welcome the benefit of a digitally connected critical enabler.  The adoption of a digitally savvy learning centre is often viewed a disrupter to existing practice.  Given a commitment-driven learning centre model, technology offers the opportunity to transition from a compliance-based training model to one of competence.  Learning and Development practitioners should welcome the latest advances in neuroscience, Bloom’s taxonomy of learning model, and principles which guide mine safety training as outlined by the Lowell Institute for Mineral Resources at the University of Arizona. By employing digital applications to include animation, game-based simulations and immersive Virtual Reality (VR) these technologies create a viable digitally-savvy learning centre. We will outline the ingredients of a digitally enabled, or VR, Learning Centre to offer some observed benefits, successes, and potential short-comings. Much excitement in the industry surrounds implementation of simulation and/or VR headset training.  Given fair consideration of these as a ‘fit-for-purpose’ solution we examine the paradigm shift required to create real results for on-the-job learning.  Interim steps may be needed to meet the cultural transformation.   Simpler forms of VR, in the form of 3D models and VR environments as displayed on a large interactive touch screen, can serve to bridge this challenge and address a group learning environment. Features of the interactive 3D technology and ease of adoption are presented.  Usage of the touch screen is similar to that of a smart phone. It may be implemented as an obvious transitional tool.  To help describe merits of the interactive touch screen the presentation points out these sample underground and surface mine training applications. There are 3-D simulations such as ventilation, emergency response, support installation, and mine cycle and activity scheduling programs. These applications offer the ability to conduct entry examinations, complete digital pre-use checklists, and perform planned task observations in the virtual world of work. The tool may be used to teach the flow of hydraulics and do fault-finding on machinery such as loaders and dump trucks. Learners may navigate in a virtual mining environment to identify hazards, detect and assess abnormal ground conditions, address poor design features, and alleviate traffic constraints. It is possible to use connected physical controls to navigate machinery in the virtual environment. We conclude the presentation with a “compare and contrast” approach to cite potential cultural benefits by adopting a transitional method. 

May 4, 2025

By Sina Z. Yekta, Zhangwei Ning, Pierre Frappin

This paper describes a DC (direct current) electrical resistivity method, which uses the contrasts in resistivity measurements to estimate the diameter of jet grouted columns as soon as they have been completed, with varying depth and water table, and without excavation. The measurement procedure is illustrated by several examples of application sites, including the Grand Paris tunneling works during the last 3 years where the method was systematically recommended in quality control for jet grouting works.

Sep 8, 2021

By B P. Banerjee, D Patra, S Raval

Roof bolts are an essential component of roof support systems in underground mines. They are used to provide structural support to the roof of the mine and prevent it from collapsing. Therefore, it is imperative to perform regular assessments of these roof bolts to avert any hazards. Manual investigations of roof bolts are done by surveyors in underground mines, which is extremely timeconsuming and challenging due to the low-light conditions in underground mines accompanied by stringent mine access rules. To this end, automated recognition of roof bolts in 3D point cloud data obtained through laser scanning in underground mines serves as a potential solution to aid roof bolt monitoring. With the continuous advancements in laser scanning-based 3D data acquisition systems, the feasibility of making such surface estimations from 3D point cloud data has increased severalfold.

Sep 1, 2024

By E Villaescusa, C Drover

The stability of access tunnels is one of the main engineering challenges in deep underground mine construction. Many underground hard rock mining operations are now reaching depths where the induced stresses are such that sudden and violent failure of the excavations can occur very soon after construction. The loading conditions on the installed ground support schemes are often underestimated by conventional engineering design methods. Therefore, the actual loading conditions often exceed the installed ground support capacity. This can result in failure of the excavations and, in extreme cases, potentially closure of mining operations amounting to hundreds of millions of dollars in lost production. More frequently, violent excavation instability at great depth causes operational delays, costly and unplanned rehabilitation, as well as risks to worker safety. In order to address this challenge, this paper briefly summarises a modern, innovative approach to the design and construction of mine development at great depth. The process follows seven main steps. The first step is to characterise the rock mass strength, structure and stress. The second step is a stability assessment, which identifies the plausible modes of excavation failure, based on the rock mass characterisation. The third step is the definition of an excavation geometry which is harmonic to the high stress conditions. The fourth step is to prepare a site-specific face destressing drill and blast design which will reduce the potential for rock mass instability during the development construction cycle. The fifth step is to accurately quantify the expected loading conditions on the installed ground support. The method of doing so is uniquely analytical and probabilistic. It is based on the natural mechanical relationships between rock strength, structure, induced stress and the physical characteristics of the instability, including its mass and ejection velocity. The sixth step of the design process is to specify a ground support scheme arrangement with sufficient strength and displacement capacity to exceed the rock mass demand by a safe margin. The final stage is to install the complete ground support scheme using mechanised technologies which minimise the exposure of the equipment operators to unsupported ground at the tunnel face.

Nov 29, 2022

By Yesil MM, Bozdag T

The swelling process is an impor- tant problem causing damages to the structures in or on swelling rocks, both during construction and operating life. To understand swelling problem, a number of testing methods have been developed by many researchers. In these studies, the swelling parameters, in most cases, are derived from oedometer tests. The swelling parameters determined from oedometer type tests represent one-dimensional behaviour (one-dimensional swelling law) therefore, it is quite difficult to extrapolate the oedometer type test results to the three-dimensional in-situ conditions. To overcome these problems, a three-dimensional approach is suggested for clay bearing rocks. Results of triaxial swelling tests conducted on marl from Dodurga Lignite Coal Mine are presented. Triaxial swelling characteristics of the marl are presented and design approach for tunnels is described.

Jan 1, 1992