Search Documents

By A. G. Mayton, D. H. Ambrose, C. C. Jobes, N. K. Kittusamy

In a systematic study, the National Institute for Occupational Safety and Health (NIOSH) evaluated seat designs in low- and mid-seam shuttle cars during production operations at two underground coal mines in southern West Virginia. The purpose was to support, with additional data, earlier findings that NIOSH ergonomic seat designs (featuring viscoelastic foam padding and lower-back support) may help reduce health risks to operators of coal mine shuttle cars. Eight shuttle car operators evaluated seven seat designs (one already in use in each vehicle and five NIOSH designs) relative to perceived and measured whole-body vibration (WBV) exposure (including vehicle jarring/jolting) and discomfort. Operators’ perceptions using a visual analog scale (VAS) and questionnaire ratings were compared with International Standards Organization (ISO) 2631-1:1985 fatigue-decreased proficiency (FDP) limits and measured WBV levels on low- and mid-seam shuttle cars. Objective and subjective data results indicated that NIOSH seat designs (with added adjustability, lower-back support and improved seat padding) performed better to reduce vehicle jarring/jolting levels and that shuttle car operators favored them over existing seat designs. The NIOSH low- and mid-seam shuttle car seats showed 45 to 77 percent better performance in FDP and 9 to 60 percent better performance overall in operators’ ratings. Considering the VAS results for low- and mid-seam shuttle cars under no-load conditions, operators rated the level of jarring/jolting 18 to 89 percent lower with the NIOSH seats. Reductions in measured vehicle jarring/jolting were 19 to 46 percent for the three-directional vector sum accelerations relative to the existing seats on the low- and mid-seam shuttle cars. Questionnaire responses indicated that operators for both shuttle car models rated NIOSH seat designs as more comfortable overall. Vehicle operators most frequently suggested adding armrests to improve the seats on the mid-seam shuttle car. A suggested improvement for the low-seam shuttle car was to make the seat a better fit for the operator compartment, which would enhance clearance between the operator and vehicle controls and allow for better seat adjustment and operator visibility.

Jan 1, 2009

By M. Heger, V. Lund, P. Mongeon, D. Bogunovic, V. Kecojevic

The U.S. coal mining industry consumes a significant amount of energy, primarily diesel fuel and electricity. The continuous global increase in energy demand, high energy prices and environmental issues related to carbon dioxide emission represent a substantial challenge for the mining industry. This paper presents the result of research on development of an integrated data environment system for analysis of energy consumption in a surface coal mine. A case study on an operating surface coal mine is carried out to demonstrate the practical application of the developed system. The research work presented here may be used by mining professionals to help provide the answers to the crucial questions of when, where and how much energy is being used. This developed system represents a framework for efficient management of energy consumption.

Jan 1, 2009

By Bradford F. Townsend, Marc R. Kritzer, Michael F. Roach, Dennis Ofiara

All Rights Reserved. Printed in the United States of America. Information contained in this work has been obtained by SME, Inc. from sources believed to be reliable. However, neither SME nor its authors guarantee the accuracy or completeness of any information published herein, and neither SME nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that SME and its authors are supplying information but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Any statement or views presented here are those of the authors and are not necessarily those of SME. The mention of trade names for commercial products does not imply the approval or endorsement of SME.

Dec 1, 2008

To improve the level of hearing protection by providing workers with an inexpensive, easy-to-use device to check earplug fit. Background Approximately 30 million workers are exposed to hazardous noise on the job, placing them at risk of permanent hearing loss, tinnitus, and other disorders. Although the preferred solution is to eliminate noise through engineering controls or to reduce noise exposure through administrative controls, hearing protectors are critical when noise is unavoidable. Studies of hearing protector users have shown that average protection values in the real world are much lower than the labeled noise reduction ratings determined in laboratories with trained and motivated subjects. Even worse, many hearing pro­tector users get virtually no protection at all because of poor fit. The studies also show that users have a harder time achieving adequate protection levels with earplugs than with earmuffs. It?s difficult for users to tell if earplugs are working well just by looking at them. A more accurate approach is to check how much they block or ?attenuate? noise. Earplugs vary in their attenuation characteristics, with most providing a maximum of 20?35 decibels of noise reduction when worn correctly. Any earplug that?s suitable for use in noisy settings will attenuate noise by at least 15 decibels. Personal fit testing is an effective way to help hearing protector users improve the fit and protection levels of the devices. However, existing fit-testing systems are expensive and unsuitable for use at many industrial worksites.

Dec 1, 2008

By Michel Aubertin

Using mine wastes as backfilling material for underground stopes has been a common practice for more than 60 years. Waste rock and tailings are used as filling materials because they are available at a reasonable cost to support the rock walls. Backfilling is also very advantageous because it reduces the amount of mine waste disposal on the surface. In underground mines, the backfill must first ensure stability of the opening, while increasing recovery of ore and minimising dilution. It is thus critical to accurately evaluate the pressures exerted on the walls and on the barricades placed near the base of the stope. In this presentation, existing solutions for evaluating the stresses on stope walls and barricades are briefly reviewed. The authors then present recently developed analytical solutions that take into account the stress transfer from the backfill to the walls in the stope and access drift. The stress state solution, which is based on arching theory, considers the influence of the stope geometry and barricade position within the drift. The method gives the pressure generated by partly or fully submerged backfill. The solutions apply shortly after backfill deposition, when the effect of pore water pressure cannot be neglected, and also for long term conditions under a fully drained state. Experimental testing and numerical modelling results are used to validate the proposed equations. Both numerical and analytical results show that the total pressure on barricades can be significantly increased by water pressure, while the effective stress is decreased (compared to dry or drained conditions). A discussion follows on the implications of the results for backfill applications.

Nov 1, 2008

By Pascal Lesagel

Life Cycle Assessment (LCA) is a holistic environmental assessment tool that allows the compilation and evaluation of the inputs, outputs, and potential environmental impacts of a product or service throughout its life cycle, from cradle to grave (i.e., from resource extraction and transformation to final disposal, including production and use stages). The relevance of LCA for the mining industry is twofold. First, the mining industry has a role in providing the LCA community the data that allows subsequent evaluations of the life cycle environmental impacts of primary materials such as metals, as well as the environmental comparison of the downstream products of the mining industry with other competing materials for specific uses. Second, the mining industry can use LCA in order to evaluate the environmental impacts of its activities, identify their environmental hotspots and compare the impacts of available technical options. For example, the environmental impacts of different extractive and processing technology can be compared through the use of LCA. This latter use of LCA by the mining industry is less common. This paper discusses the use of LCA to compare sulphidic tailings management options. The paper also presents some of the LCA research challenges that still have to be addressed to increase the relevance of LCA results for the specific context of mining activities.

Nov 1, 2008

By John A. Organiscak

Enclosed cabs are a primary means of reducing equipment operators? silica dust exposure at surface mines. The National Institute for Occupational Safety and Health experimentally investigated various factor effects on cab air filtration system performance. The factors investi­gated were intake filter efficiency, intake air leakage, intake filter loading (filter flow resistance), recirculation filter use, and wind effects on cab particulate penetration. Adding an intake pressurizer fan to the filtration system was also investigated. Results indicate that intake filter efficiency and recirculation filter use were the two most influential factors on cab penetration performance. Use of the recirculation filter reduced cab penetration by usually an order of magnitude over the intake air filter alone because of the multi­plicative filtration of the cab interior air. Intake air leakage and filter loading affected the cab penetration to a lesser extent, while wind had the least impact on cab penetration between the calm and 10-mph wind velocities tested. Adding an intake pressurizer fan notably increased intake airflow and cab pressure with only minor changes to cab penetration. A mathematical model was developed that describes cab penetration in terms of intake filter efficiency, intake air quantity, intake air leakage, recirculation filter efficiency, recirculation filter quantity, and wind penetration.

Nov 1, 2008

To reduce operator exposure to drilling noise from roof bolting machines. Background Noise-induced hearing loss (NIHL) is a prevalent occupational illness in the United States. Studies indicate that 70%?90% of miners have NIHL significant enough to be classified as a hearing disability. Mine Safety and Health Administration studies indicated that roof bolting machine operators are among those overexposed to noise. Field studies support the premise that, on average, drilling is the loudest noise source to which a roof bolting machine operator is typically exposed and contributes greatly to the operator?s noise exposure. The National Institute for Occupational Safety and Health (NIOSH) has further determined that the drill steel and chuck radiate a significant amount of noise during drilling. To address this noise hazard, NIOSH developed a collapsible drill steel enclosure (CDSE) to encapsulate the drill steel during the drilling portion of the roof bolting machine duty cycle. In addition, NIOSH is collaborating with J. H. Fletcher & Co. in the continued development of a CDSE.

Sep 1, 2008

To minimize the equipment operator?s respirable dust exposure in enclosed cabs of mobile equipment by install-ing cab filtration and pressurization systems and by keep-ing doors and windows closed. Background Enclosed cabs are used on mobile equipment to protect operators from health and safety hazards. The primary health concern is overexposure to respirable dust. Examples of such equipment in mining include drills, dozers, haul trucks, and other equipment. When equipment is new, the operator?s dust exposure is normally at acceptable levels. As the equipment ages and gaskets and seals deteriorate, the air quality inside an enclosed cab can reach a point where it is no longer at acceptable levels for the equipment operators. In an effort to improve the air quality in enclosed cabs of older mining equipment, NIOSH has been performing research to retrofit cabs with new filtration and pressurization systems. Over the past few years, this research has shown that retrofit systems can substantially improve the cab?s air quality back to safe and acceptable levels. How-ever, this is only possible when a positive cab pressure is achieved and maintained. Thus, when a cab door or window is opened, the cab pressure drops to zero and the cab filtration and pressurization system is rendered ineffective. During a recent field study, the magnitude of this impact was noted when a drill operator repeatedly opened the cab door throughout the course of the drill cycle. Upon closer examination, it was determined that the cab door was being opened to manually guide the next drill steel into place each time an additional section of steel was needed to drill deeper holes.

Sep 1, 2008

By Sean Gallagher

This report was written in an effort to provide better control measures for low back pain (LBP) and low back disability in the mining industry. There are numerous factors associated with development of LBP, many of which can be effectively controlled while some cannot. Better job design is promoted as the best method of reducing cases of LBP and can also reduce the disability (i.e., lost time from work) associated with LBP when it happens. The report draws attention to what is currently known about LBP, what the causes are thought to be, and discusses recent back injury trends in the mining industry. Research describing unique physical demands in mining, such as the capabilities and limitations of working in awkward postures, is also presented. Methods that can be used to prevent initial LBP episodes are provided, including facilities design and layout for materials and supplies, use of mechanical-assist devices, improved design of lifting tasks, and better seat design. Methods of reducing the disability associated with LBP (including workplace design, proactive return-to-work efforts, communication, and management commitment) are also discussed. The report concludes that control of LBP and disability in mining requires a comprehensive approach to limit the repetitive loading that can occur on the low back due to manual materials-handling tasks and exposure to whole-body vibration (WBV). Specific recommendations include the following: ? Successful LBP prevention efforts require a proactive program that has strong management commitment and incorporates employee involvement. ? More efficient supply handling systems and use of mechanical-assist devices can greatly reduce exposure to hazardous lifting tasks. ? Lifting tasks should be designed to minimize low back stress. Tools to evaluate and redesign lifting tasks are presented. ? Improved seat design can reduce exposure to WBV and improve posture, leading to reduced LBP risk. ? The disability associated with LBP can be reduced. Getting the worker back on the job as quickly as possible is in the interest of everyone involved.

Sep 1, 2008

To develop effective noise controls for continuous min-ing machines (CMMs) to reduce worker noise exposure. Background Noise-induced hearing loss (NIHL) is an occupational illness caused by chronic exposure to excessive sound levels. For underground coal mine workers, NIHL continues to be a serious health issue. Analysis of hearing loss data suggests that by retirement age, 70%?90% of U.S. coal mine workers will have a hearing impairment. Operated in the confined spaces of underground mines, large industrial mining equipment often produces sound levels that can be harmful to workers. Of all equipment used in underground coal mining operations, CMMs account for the most noise overexposures. To reduce the occurrence of noise over-exposures, engineering noise controls must be developed for the CMM.

Sep 1, 2008

By R. Karl Zipf

This report presents nearly all structural data available from explosion tests of 20-psi mine ventilation seals and concrete-block ventilation stoppings that were conducted by the National Institute for Occupational Safety and Health during 1997?2008. Although the seals tested were designed to meet the former federal 20-psi pressure design standard, the structural information contained herein on these seal tests will facilitate the analysis and design of coal mine seals that meet the new explosion pressure design criteria of 50 and 120 psi as set forth in the Mine Safety and Health Administration (MSHA)?s final rule on ?Sealing of Abandoned Areas.? The seal testing data are organized into six broad categories of seal structures based on the materials used and the construction method for those 20-psi seals: 1. Concretelike materials with steel reinforcement and reinforcement bar anchorage to rock 2. Pumpable cementitious materials of varying compressive strengths with no steel reinforcement and no hitching 3. Articulated structures such as solid-concrete-block seals and ventilation stoppings made of solid and hollow-core concrete blocks 4. Polymer and aggregate materials without hitching 5. Wood-crib-block seals with or without hitching 6. Articulated structures such as lightweight blocks with or without hitching This summary contains data on 52 different structures in the above categories?44 seals and 8 ventilation stoppings. The structural data sets include the applied loading on the tested seal represented by a pressure-time curve and, when available, the measured seal response represented by a displacement-time curve. The structural data sets enable the calibration and verification of numerical models of seal behavior at the 20-psi level, which may then facilitate future structural analyses of seal designs for the new 50- and 120-psi explosion pressure design criteria.

Aug 1, 2008

Objective: To enable mine operators and mine inspectors to make quick and accurate measurements of the explosible nature of coal and rock dust mixtures.

Jul 1, 2008

By A. Dave Mackintosh

The Current demand for potash has pushed world prices to record levels and allowed Saskatchewan producers to operate at maximum capacity. Several years of strong demand has resulted in a permitting rush not seen since the 1960?s. Even though Saskatchewan has a huge potash resource, mining and processing constraints will limit the areas of economic development. Introduction In 1969 M. E. Holter prepared a report ?The Middle Devonian Prairie Evaporite of Saskatchewan?, published by the then Dept. of Mineral Resources. Holter?s report has remained the bible of geologists working in potash ever since. It is astounding that a report written before there was really much potash mining history in the province, is as valid today as when it was first published. This paper re-iterates much of Holter?s report and adds a little mining experience to essentially confirm the importance of his work.

May 1, 2008

By Chris Brothen

The introduction of new technology in mine operations has provided real opportunities for increased efficiencies and production gains which translate into enhanced profits. Computing and network technology usage has become integrated into surface mining operations and on average these investments in technology have proven beneficial for efficiency and productivity improvements. Embracing new technologies however, does not guarantee positive results. The expectations or improvements derived through the technology must be confirmed and clarified well before implementation. Tire Pressure and Temperature Monitoring Systems are an excellent example of an existing technology that can provide full time automated performance measurements of tires operating under harsh conditions and environments. Prompt warnings or alarms signaling when a tire has exceeded operating capacities will provide savings through lowered maintenance costs and increased productivity. To truly quantify the projected savings in tire life, fuel consumption, and increased levels of production, all costs associated with the technology, both direct and indirect must be considered. Apart from the initial cost of the system implementation, ongoing maintenance and support costs must be considered as well as the costs of system integration into existing mine operations

May 1, 2008

By Dianne M. Lapierre

Mining firms in Canada are increasingly incorporating the social and environmental interests of their stakeholders into their projects in an effort to become more sustainable. Such initiatives have included negotiating Impact and Benefit Agreements (IBAs) directly with would-be impacted, often aboriginal, communities near resource developments in the Canadian north. Why does a mining firm take on this extra time-and cost-intensive initiative when governments and regulatory measures are in place to address social and environmental issues? Past research has paid little attention to the corporate rationales for IBAs. Based on document review and interviews with mining executives, this study investigates the rationales of mining firms that ?over-comply? with legislative requirements by negotiating IBAs or similar types of agreements with communities. The results indicate that mining firms increasingly recognize IBAs as an intrinsic part of the permitting process. When queried, executives regularly identified the negotiation of agreements as ?the right thing to do?. While this response could be read in ethical terms, a commercial rationale is also clearly present. By building strong relationships with nearby communities, addressing community concerns, and directing benefits to local people, all of which are explicitly achieved with an IBA, mining firms are maintaining their long-term financial viability, thus their sustainability, within an evolving industry.

May 1, 2008

By Jessica Barber

Problem ? Mining operations consistently need equipment that is available, and able to perform to its maximum potential ? The most difficult part of a Maintenance Manager?s job is often a lack of knowledge on how long their equipment has to last ? The short term view can lead to interim fixes that accumulate into larger problems ? It is always difficult to justify major overhauls and upgrades when there is pressure to meet mine plan production targets

May 1, 2008

By Gerardo Noriega

Aeromagnetic compensation plays an important role in most airborne geophysical exploration programs, dealing with the modelling and elimination of interference effects generated by the aircraft flying in the Earth’s magnetic field. This work discusses broadly recent developments on adaptive compensation (which allows continuous optimization of the solution through a recursive algorithm), real-time compensation of on-board electronic systems (whose effects are not captured by the conventional model), attitude-reference sensors, compensation of UAV platforms, and various modelling issues.

May 1, 2008

By Robert J. McCarthy

There are two things on everyone's lips when mining folks gather these days - one is the exciting business opportunities that now exist for mine development and expansion, and the other is the dire shortage of human resources needed to design, manage, and even operate the mines. Years of stagnant industry growth, limited employment opportunities, and unwarranted perceptions of remote and harsh working conditions have caused mining to be a less than desirable career choice. Attrition and reduced entry to the workforce has resulted in shortages for not only mining professionals, but also skilled trades people and operators. Consequently, to survive, let alone grow, mining companies, suppliers, and educators are all pursuing innovative solutions with technology, inter-industry recruiting, centralized services, and strategic partnerships. This paper describes some of these initiatives and proposes others, now that the people are gone!

May 1, 2008

By Rildo Rodríguez, Dante Soberon

En el presente estudio se ha tomado en consideración diferentes aspectos geológicos que ayudan a determinar importantes controles estructurales que estuvieron activos en diferentes etapas de la evolución andina. El reflejo de la actividad de estas fallas se manifiesta por la presencia de controles estratigráficos, cambio brusco en la dirección de los ejes de pliegues y emplazamiento de pequeños cuerpos magmáticos, así mismo se encuentran relacionado al emplazamiento de mineralización de estaño, oro, uranio y tierras raras.

May 1, 2008