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By Su-Ping Peng

Three dimensional (3D) seismic exploration has been carried out since the 1980s in the mining district of China, where it has been playing an indispensable role in the high yield and efficiency of coal mining. Unlike oil exploration, this technique uses high density seismic acquisition technology. In recent years, it has focused on wide azimuth 3D seismic acquisition. Evaluation of geometry moved away from depending on folds, azimuth and offset, toward being based upon a focus-ray beam. Conventionally, coalfield 3D seismic interpretation focused on time domain and was based on kinematics information, which is only suitable for less complex geological conditions. To achieve high-resolution processing for the complex topography and structure in coalfields, data processing shifted from poststack to prestack. The means to improve the accuracy of interpretation for complex geological conditions are 1) integration of multiple attributes and multiple disciplines, 2) combination of seismic and geological data, and 3) comprehensive combination of time domain and depth domain data. With the demand for lithological exploration, high-resolution data processing must also take into account the requirements of preserving amplitude in seismic data. Seismic attributes technology, seismic inversion technology, and dynamic tracking interpretation are key techniques in 3D seismic exploration. They greatly improve interpretation accuracy, produce better results in the goaf space description of the coal-bearing strata and coal seam structure, and effectively reduce exploration costs under complicated geological conditions. Therefore, these techniques will be the primary means employed in the future to deal with coalfield complex structure and lithological exploration.

Aug 1, 2013

By Omkar N. S. Beruar

Extraction of sill pillars has always been problematic because of high risk of seismicity and rockburst. Depending on a number of factors, a sill pillar can undergo different failure modes and cause problems in the mine. Of these, sudden and uncontrolled failure of part(s) of the pillar leading to highenergy seismic events and rockbursts is a main concern because it is not possible to predict the location and time of a rockburst apart from its potential to cause extensive damage to the mine structures. To date, a comprehensive technique for sill pillar design and recovery does not exist. Conventional methods of pillar design, such as the pillar stability graph method, are utilized to design stiff sill pillars. In these design approaches, the post-peak response of the pillar-rock system is not considered. This is in part due to a lack of clear and comprehensive understanding of the post-peak behaviour and failure mechanism of sill pillars. In general, the strength of a rockmass is described using a failure criterion. When stresses reach the strength of the rockmass, the rockmass does not necessarily become unstable and knowledge of the loads alone is not enough to assess the instability conditions accurately. In fact, it is not possible to predict instability of rockmass based on the strength/stress ratio alone because instability depends not only on this ratio but also on the loading condition and loading system characteristics. The loading system can dictate whether the sill pillar will go through a stable or unstable failure process. This paper examines the influence of various parameters such as the pillar width to height ratio, the extraction rate, and placement of backfill on the Loading System Stiffness (LSS) and the Pillar Stiffness (PSS). The ultimate goal is to design yielding sill pillars that would yield in a stable manner and will reduce the risk of pillar rockburst. Plane strain finite element analysis is conducted using the generalized Hoek-Brown failure criterion with elastic-brittle-plastic parameters. Examples are given to demonstrate how to calculate these stiffness values and assess the stability condition of sill pillars. It is found that increasing the rate of extraction increases the likelihood of unstable yielding of the pillar as has been found in other studies. Placement of backfill in a timely fashion in the stopes above and below the sill pillars increases the stiffness of the loading system. This indicates that backfilling of stopes while creating the sill pillar increases the likelihood of stable yielding of the sill pillar.

Aug 1, 2013

By John R. Craynon

Science and Sustainable Development Each of the ?pillars? of sustainable development are directly impacted by mining. We need science to understand exactly how mining contributes to each. Overview of presentation ? History of mining and sustainable development ? Role of stakeholders in measuring/accepting contributions of mining to SD ? Identified ?shortfalls? in understanding mining and SD ? Science needs

Aug 1, 2013

By Lassaad Hazzar

The ultimate lateral resistance of piles in cohesive soil is studied using the well-known finite difference code, FLAC2D. The Modified Cam Clay (MCC) constitutive relation is adopted in the analyses to model the cohesive soil behavior, whereas the structural pile model with three degree of freedoms, available in FLAC2D library, is adopted to model the piles. The reliability of Broms's method, still used in the current design practice of piles under lateral loads, is verified. Comparisons between the ultimate lateral resistances of piles and those deduced from the graphs proposed by Broms (1964) are presented in graphs. Different factors thought to affect the lateral resistance of piles in cohesive soil, not adequately considered in Broms's method, such as clay stiffness, pile length, pile diameter and axial load are parametrically studied. A special concern is devoted to elucidate the effects of over-consolidation ratio (OCR) on the ultimate lateral resistance of piles in cohesive soil.

Aug 1, 2013

By L. Li

To accommodate the large payloads and harsh operating conditions associated with heavy vehicles in the mining industry, off-the-road (OTR) tires are typically used with heavy mining vehicles. These tires have increased abrasion and wear resistance due to their thicker tread, sidewall and bead thicknesses. Given these features, OTR tires are much stiffer than conventional passenger vehicle tires and cannot be mounted to a single-piece rim without damaging the structural integrity of the tire during the mounting process. Therefore, multi-piece wheels are used with OTR tires to facilitate mounting. While these assemblies are necessary, several instances of their failure have been reported to result in injuries or fatalities within the mining workplace. Many of these failures were specifically reported to be caused by the disengagement of the wheel lock ring - a component used to securely engage the assembly during operation. In this study, a threaded-connection locking mechanism has been proposed in place of the traditional lock ring design. The performance of this threaded-connection was numerically evaluated in a pull-out test against a conventional five-piece wheel assembly. The pull-out test was devised as a means of quantifying the engagement ability of each wheel?s locking mechanism. A high degree of modelling accuracy was maintained throughout the analysis by validating the vertical and horizontal static loaddeflection behaviour of the rim model of the five-piece wheel assembly against experimental data. Through validation, the model data were found to be within 10.5 and 4.80 %, for vertical and lateral loaddeflection behaviour, respectively. Results from the pull-out analysis found that the threaded-connection demonstrated a 113 % increase in the force required for disengagement to occur relative to the conventional five-piece design - a force of 9,550 kN in total.

Aug 1, 2013

By Shugang Li

Coal and coal-bed methane are valuable energy resources. If they can be extracted simultaneously and safely, the triple purposes of mine safety production, new energy resource supply and environmental protection can be fulfilled. After mining, the mining induced fissure distribution feature and methane delivery behavior in overlying strata were closely related to the relieved methane degasification. Using physical simulation and numerical simulation, it was explained that the distribution feature of mining induced fissure was the Elliptic Paraboloid Zone (EPZ) in three-dimensional space. Based on the key stratum theory, the types, parameters, characteristics and dynamic evolution behavior of the mining induced fissure EPZ were analyzed. Applying environmental fluid mechanics and the mass transfer theory, the relieved methane floating-diffusion equation of the EPZ was established, and the corresponding transport process was analyzed. Using the field practice of relieved methane degasification in Tianchi Coal Mine, it explained that the mining induced fissure EPZ was the storage and delivery area of relieved methane. The degasification effect will thus be useful if the drainage system is laid in the EPZ. Such studies can provide the theoretical basis and technical support for the safe simultaneous extraction of coal and methane.

Aug 1, 2013

By D. D. Liu

This paper proposes a charge induction dust measurement method based on detrended fluctuation analysis (DFA) for use in coal mine environments, based upon electrostatic interference, dust properties, wind speed, particle size, moisture content and other factors. In this methods, sequence x(t) is first obtained through a dust concentration sensing probe, and then the cumulative deviation y(t) is calculated, and y(t) is divided into same lengths. Secondly, a first-order linear fit is used for data of each interval, and mean-square deviation filtered DFA was calculated for each interval. Finally, the dust mass concentration of the corresponding time is obtain by supplemented calibration coefficient and fitted the data point which is the mean and square root for all lengths of interval. Simulation and verification experiments showed that the charge induction dust measurement method based on DFA can reduce coal mine electrostatic interference effects with high accuracy. The design has been successfully applied to select areas.

Aug 1, 2013

The goal of this presentation is to firstly, review mine effluent permits in a number of regulatory jurisdictions; and secondly, to develop a strategy for incorporating the regulatory requirements into the environmental assessment (EA) process for new mine proposals. The focus was on the province of British Columbia (BC) and their recent initiative on the One Project, One Process initiative. This task was approached by reviewing mine effluent permits for various regulatory jurisdictions and comparing them to BC mine effluent permits. This comparison revealed a variety of approaches for designing mine effluent permits, but there is a common scientific approach, which supports the conclusion that the permitting of mine site discharges can be designed based on a scientific approach. This approach is expected to: (a) achieve sound environmental protection, (b) demonstrate the application of Best Achievable Technology, (c) incorporate sound sustainability approaches, (d) incorporate regulatory objectives, and (e) create efficiencies for the regulator and mining industry. There is an essential precursor to developing a sciencebased effluent permit for which the proponent must provide: (1) the necessary technical assessment information to demonstrate the mine effluent permit application will result in an environmentally protective effluent discharge, to the satisfaction of the permitting agency; (2) the necessary level of detail for essential mitigation pollution control works to demonstrate how they will be operated to achieve the necessary treatment goals; (3) the necessary level of detail for non-treatment mitigation (passive treatment, or passive pollution control); and (4) the necessary level of detail to demonstrate how pollutants will be prevented from being mobilized (or being generated) from ore and waste materials, or, if the pollutant originates from an added milling reagent, how the reagent will be reduced. While (active) mitigation pollution control equipment is more definable in an effluent permit, non-treatment mitigation is more nebulous in terms of defining in a mine effluent permit; it is therefore recommended that appropriate management plans be developed for essential mitigation pollution control and non-treatment mitigation (passive treatment) and submitted with the proponent?s EA/effluent permit application packages. Major deficits in adequate active and passive pollution control will inevitably lead to regulatory impediments to developing a permit and allowing a mine to be developed, although EA processes strive to preclude major permit information gaps; the onus is on the proponent to provide complete information in this area. Hence the importance of EA processes ensuring that the major technical information requirements for effluent permit development are included in the EA phase. Recently, this aspect of the mine EA process has taken on a new role under the political efforts of One Project, One Review Process (Canadian) and One Project, One Process (in BC). These initiatives translate, in part, to ?synchronous permitting? (in BC): effluent permitting, for example, may be initiated shortly after the proponent submits the EA application to Ministry of Environment.

Aug 1, 2013

By Marketa D. Evans

The mining industry has a significant opportunity to capitalize on its past learnings in order to build better social relationships. The industry?s relationship with society is both critical and under pressure. Rising levels of public opposition and social conflict are already having material impacts on operations around the world. Industry has an opportunity to shape the future direction of this social engagement, build public trust and proactively respond to a material risk to operations, but first it needs to better understand the nature of the challenges and the urgency of addressing them.

Aug 1, 2013

By H. H. Wang

Construction safety documents regulate significant safety actions and requirements by which construction workers or employees should abide in order to secure them from occupational hazard events. Therefore, facilitating faster identification of applicable safety requirements from the documents has become an important topic in the construction safety domain. To address the need in this regard, tools and techniques have been developed and research efforts have been made. One of the research efforts is to utilize ontology, a knowledge representation and reasoning approach, as the methodology to achieve the goal of identifying applicable safety requirements. In such ontology-based researches, the development and construction of the safety concept ontology is an essential task as the concepts and the relationships between the concepts both representing key safety knowledge need to be carefully identified. In this paper, the author focuses on the safety documents without predefined concept structure and aims to address the concept and relationship identification difficulties. Specifically, the author leverages the Formal Concept Analysis (FCA) methodology, a theory of data analysis that identifies conceptual structures among data sets, to mine and analyze the documents in order to discover safety concept structure and to further assist the development of the concept ontology for the construction safety documents. The author expects the application of FCA to construction safety domain can eventually benefit the ontology-based approaches for identification of applicable safety requirements.

Aug 1, 2013

By Patrick Cloutier

Presentation objectives ? Introduce discrete-event 3D computer simulation as a tool to design, improve and optimize construction projects: ? Describe a real typical construction project planning issue. ? Present an applied use of simulation to solve this issue. ? Detail benefits of using simulation versus traditional planning methods.

Aug 1, 2013

By Andrew Bamber

The mining and beneficiation of minerals is the second largest end-use of electrical power on the planet, and comminution is by far the largest single contributor to this. Several jurisdictions, including British Columbia, have, in response to concerns about greenhouse gas emissions and climate change, adopted energy conservation legislation, including carbon taxes, carbon trading and conservation incentive schemes. Key to achieving conservation objectives is firstly an understanding of usage metrics across the various unit operations in the sector, and secondly an understanding of the conservation potential represented by available technologies and approaches in reducing end-use. This paper presents the results of a recent utility-funded study on energy use metrics and conservation potential at large open pit mines which are typical of the sector in BC.

Aug 1, 2013

By K. A. Mackinnon

The choice of fan type (axial flow, centrifugal or mixed flow) most suited for a mine ventilation application depends on a number of technical and economic factors. For each project, the relative importance of these factors will vary. It is worthwhile to carry out an assessment on a case by case basis. The paper, by discussing a number of technical and economic factors and their interactions, will provide the ventilation official a methodology to easily and methodically undertake such an assessment.

Aug 1, 2013

By J. G. Bennett

Coal consumption has increased globally by 57% over the last ten years. Underground mining typically provides coal of the highest calorific value and accounts for the greatest proportion of production. Despite a negative environmental image and indeed impact, this industry appears likely to thrive on the global scale for many years to come. Such mining consumes large amounts of electricity with implications for carbon dioxide emission at power plants and emits substantial quantities of the powerful greenhouse gas methane. In response to this significant carbon footprint, the European Union has funded research to examine the potential for a range of improvement technologies in a project entitled Low Carbon Mine Site Energy Initiatives (LOWCARB). Coal properties related to seams and mines, together with longwall characteristics, provide the basis for research into modelling optimally efficient methane drainage with a view to assisting mining as well as maximising electricity generation at surface and hence oxidation of the methane. Possible systems for the oxidation of very low concentration methane in ventilation air, which contributes the greatest greenhouse gas impact due to the volumes emitted, have been studied and modelled. Simulation and investigation of intelligent optimisation of electricity demand patterns provide the basis for reducing the demand peaks at mines and hence the cost and ultimately the carbon footprint of a mine, while specific investigations have been undertaken into ventilation efficiency at an unusually challenging mine and simulation of mine water pumping in order to develop an innovative method to monitor pumping systems efficiency. For post-mining use, the potential of disused shafts for compressed air energy storage to improve the operation of future electricity grids with high renewable energy penetration by reducing peak generation capacity requirements has been studied. While underground coal mining will always by definition be related to a significant carbon footprint, this paper provides an overview of a set of initiatives that can make a positive environmental impact while controlling costs across a huge global industry.

Aug 1, 2013

By Nicholas C. Williams

This paper presents the development of a demand reduction and responsive strategy capable of reducing the electrical power demand, particularly during peak conditions. The work presented includes a case study of a UK colliery. Areas explained are the equipment installation at the mine; the development of the demand reduction strategy including the load profile database and prediction optimisation model. Some live production data from the power meter installation at the mine is also presented.

Aug 1, 2013

By Mousa Mohammadi

Due to operational advantage of dragline in simultaneous excavation and back-filling, the equipment has gained vast importance in open-pit mining. Besides, absence of auxiliary haulage units and a myriad of other benefits are also credited in favor of excavation of muck piles by the draglines. However, the aspects of production, productivity and economics are of utmost significance in dragline operation and planning. In this light, the present paper is an endeavor to analyze availability and utilization of dragline operations. The paper presents a good amount of data for 4-draglines operating in one of the major opencast projects in India. The study reveals the trends of availability and utilization of these draglines during last 11-years. Furthermore, the study also highlights the salient reasons for loss of available hours and for idling of the draglines. Some startling information and facts have been illustrated in form of graphs and pie charts.

Aug 1, 2013

By I. A. Kovalevska

Considered problems: elaboration and implementation of resource-saving technologies, low-cost support systems improvement, openings security and support, based on wallrock condition control with supreme implication into the rock pressure occurrence counteraction work. Results of analytic and underground investigations using computer simulation of the finite elements in order to calculate stressstrain state of the multivariable geomechanical systems are presented. Solutions of concrete objectives are found using spatial geomechanical model of solid motion around openings, considering real geomechanical parameters formation of support forms with proper conditions of their contact and real mechanical characteristics. Ultimate solutions of resource-saving technologies implementation based on the analysis of multivariate vertical, horizontal, and reduced stresses components calculation and also near-contour rock, support bearing components and security constructions movements are found. Results of experimental investigations of combined supports and security constructions, which increase openings' stability in difficult conditions of flat coal seams are presented.

Aug 1, 2013

By R. Argane

In this work we assessed the geochemical behavior of concentrator tailings deposited at the abandoned mines of Zeida and Mibladen (Upper Moulouya, Morocco), using physico-chemical analyses, mineralogical characterization, acid base accounting and weathering cell tests. The aim of the study was to evaluate mine drainage quality and to assess metal mobility from these concentrator tailings. Chemical analyses show that the Upper-Moulouya abandoned tailings contain relatively high quantities of lead (0.261 to 0.594 % wt). Mineralogical analyses reveal the abundance of neutralizing minerals (calcite, dolomite, ankerite, and aluminosilicates) which influence mine drainage and metal mobility in mine tailings. Leachate analyses from weathering cell tests show alkaline conditions, small conductivity values, and low solubility of Pb-mineral phases. According to these results, abandoned mine tailings in the Upper-Moulouya district have very low potential for generation of contaminated mine drainage and for leaching of heavy metals. However, the inhalation of tailings exposed to winds generate dust problem facing the local population and may cause health consequences.

Aug 1, 2013

By J. Kalejta

Ever increasing depth of mineral extraction presents a challenging environment for hard rock underground mines. High in-situ stresses and associated seismicity with potential rockburst hazards are the major decisive factors contributing to the choice of a ground support regime. Conventional ground support systems, designed primarily for static loads, are not always capable of providing safe working conditions for underground personnel in seismically active mines. Systems specifically developed to resist dynamic loading and allowing for larger deformations are therefore preferred alternatives. High-tensile chain-link mesh has a proven record of successful use in open cut operations in various rockfall barrier installations due to its high energy absorption capacity. It has also been used in underground operations in various parts of the world. This paper describes a method of mechanized installation of a chain-link mesh evaluated at the Kiruna mine in Sweden and South Deep Mine in South Africa. A purpose-built mechanized roll mesh handler was used in this evaluation. The handler is compatible with all standard multi-boom underground drill rigs and is operated utilizing the hydraulic circuit normally used for the feed arrangement. A number of key performance indicators have been identified as success criteria: ??A 30-50% faster installation compared to the conventional methodology ??The mesh should sustain any blast damage when applied to the blasting face ??No unraveling of the mesh when cut ??No failure of mesh under normal conditions Although the energy-absorbing mesh combined with yielding rock bolts is a ground support system of choice for rockburst prone conditions, the operational upsides recognized during the evaluation imply that this product can also be competitively used in less demanding ground conditions where customarily weld mesh or shotcrete are used as a primary surface support. The main conclusion: a fast, safe and fully mechanized installation.

Aug 1, 2013

By H. Nejati

Experimentally, the Semi-Circular Bending Moment (SCB) fracture toughness test results of Basalt Specimens Under Illumination (BSUI) have shown reduction in fracture toughness and failure force as a result of micro-cracking. The fractographic investigation of BSUI confirms initiation and extension of micro-cracks. Determination of a relation between strength reduction (herein fracture toughness reduction) and density, location and orientation of thermo-mechanical induced cracks due to microwave radiation is critically important. Numerical modeling can bridge strength reduction and the density of thermal microcracks generated due to microwave radiation. Discrete Element Modeling (DEM) is a power tool for simulation of micro-crack initiation, coalescence into macroscopic fractures and failure mechanisms in brittle rock specimens under different stress regimes (herein combination of pure tensile stress due to SCB testing, and thermal stress due to microwave radiation). For this purpose, a DEM modeling of SCB testing of basalt using EDEM (i.e., a DEM based software). DEM models are calibrated according to results of experimental SCB testing as reported in previous papers. This paper first reviews some background data on SCB fracture toughness, and experimental results of fracture toughness of microwave treated SCBs. Then it proposes a new methodology for simulation and validation of rock samples exposed to microwave illumination with regard to experimental results, and discusses the correlation between fracture toughness of BSUIs and density of micro-cracks, which is attributed to applied microwave power and duration of illumination.

Aug 1, 2013