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By J. H. Welsh

This Bureau of Mines report presents guidelines to be considered in the design, installation, and operation of environmental mine monitoring systems in underground coal mines so as to enhance safety in the U.S. mining industry. A review of the current status of mine monitoring in the United States is also provided.

Jan 1, 1987

CSA mine, which is a deep level copper operation, located 12 km north of Cobar, NSW, currently uses a top down stoping method, utilising cemented hydraulic backfill (CHF) to fill and stabilise the stoping void thus assisting the extraction sequence. The stope sequence then requires development back through the CHF stope so that the necessary infrastructure for the subsequent stoping, such as raise bore pads can be sited. The primary and secondary support installed in the CHF consisted of 100 mm thick fibrecrete from floor to floor with 7 + 2.4 m long resin support tendons installed at 1.5 m ring spacing. This support system relied on the resin achieving a quality bond with the CHF, and also the fibrecrete developing early structural strength due to the use of an accelerator. In addition to the delays in the excavation turn around time, it was felt that a superior support system could be designed. Such a system was designed; risk assessed, tested underground, and trialled in selective CHF digouts, and eventually signed off as the chosen support method in CHF digouts. This paper discusses the change from a passive support system used in CHF digouts to an active support system using Swellex bolts and weld mesh, which has provided an active support system, that is superior, faster to install, reduced the excavation turn around time and is overall a cheaper support system.

Nov 25, 2010

By Rudy J. Matetic

The National Institute for Occupational Safety and Health (NIOSH) at the Pittsburgh Research Laboratory (PRL) is conducting research to reduce the noise exposures of roof bolting machine operators and to prevent additional cases of Noise Induced Hearing Loss (NIHL) thru the development of engineering noise controls. This paper describes and evaluates an engineering noise control for the roof bolting machine, namely the collapsible drill steel enclosure. The results of the evaluation demonstrated that using the collapsible drill steel enclosure provided a 7 dB(A) reduction in sound pressure level at the operator?s position of a roof bolting machine.

Jan 1, 2008

When overburden depth exceeds economical recovery in openpit coal mines, the use of highwall mining systems has increasingly come into play. However, stability in the highwalls is always a major safety concern during such mining. The U.S. Mine Safety and Health Administration requires that highwall mining operators follow ground control plans that specify the pillar sizes necessary to prevent collapse that would threaten highwall stability.

Jan 1, 2006

By Robert L. Lagace, Michael A. Grossman, Alfred G. Emslie

This supplement to the final report is a collection of interim and monthly reports and working memoranda prepared during the course of this program to document the progress, methods and results of the work. The supplement is divided into the self-contained sections briefly described below. I. SELECTED MONTHLY TECHNICAL LETTER REPORTS - This section is a collection of selected monthly technical letter reports that briefly summarizes the chronological development of the analyses and results, including the different concepts, theoretical approaches, and methods of data reduction and analysis explored, and the discoveries, insights and findings made along the way. More detailed treatments of the key developments and results are presented in the interim reports and working memoranda reproduced in subsequent sections of this supplementary report, and in the separately published final report. II. BACKGROUND THEORY FOR MEASUREMENT PROGRAM ON MEDIUM AND HIGH FREQUENCY RADIO TRANSMISSION IN COAL SEAMS - Working Memorandum - This working memorandum gives the initial background theory needed to guide the planned measurements and data analyses of this program to describe the propagation of radio waves-in coal seams for the frequency range of 50 to 5000 kHz. III. MODELLING AND DATA ANALYSIS OF IN-MINE ELECTROMAGNETIC WAVE PROPAGATION - Interim Report - This interim report presents detailed treatments of the data analysis and modelling techniques used, and the associated results obtained from conductor-free area propagation data measured by T. Cory in the first set of six coal mines. The mines were located in three highcoal seams; the Pittsburgh seam in northern West Virginia, the Pocahontas No. 3 seam in Virginia, and the Herrin No. 6 seam in Illinois. IV. ANALYSIS OF MF PROPAGATION DATA FROM MARGARET NO. 11, NANTY GLO, EHRENFELD, AND ADRIAN COAL MINES - Interim Report - This interim report presents detailed treatments of several improved data analysis and Modelling methods applied to, and results obtained from, conductor-free area propagation data measured by T. Cory in the second set of four coal mines. These mines were located in three low-coal seams; the Upper Freeport seam in Pennsylvania and West Virginia and the Lower Freeport and Lower Kittaning seams in Pennsylvania. In addition, this report contains a reprint of two papers presented at a Bureau of Mines sponsored EM Guided Waves in Mine Environments Workshop held in Boulder Colorado. One paper describes the three-layer theoretical model and its application to the conductor-free data from the first six mines, while the second paper describes the theory developed for the coupling of loop antennas to a cable in a mine tunnel in a coal seam, and the model's application to data in the vicinity of cables taken at the Margaret No. 11 mine. V. A METHOD FOR NONINTRUSIVE, IN-SITU MEASUREMENT OF COAL AND ROCK CONDUCTIVITIES IN A COAL MINE TUNNEL - Working Memorandum - This working memorandum briefly describes a possible direct method, and its potential advantages and shortcomings, for performing in-situ measurements of coal and rock conductivities. VI. MODELLING AND DATA ANALYSIS OF IN-MINE ELECTROMAGNETIC WAVE PROPAGATION FROM 50 to 5000 kHz - Interim Report - This interim report presents a summary comparison of theoretical and experimental results for conductor- free areas in eleven coal mines located in seven coal seams. It also summarizes the findings and their implications for intrinsically-safe, portable radio communications between roving miners.

Jan 2, 1980

By Jérôme Boutin, Rémy Oddo, Sylvain Ouellette, Paul-Émile Boileau, Gilles LeBlanc, Pierre Marcotte

ackleg rock drills are widely used in the mining industry and are known to generate high levels of hand-arm vibration which contribute to the development of the hand-arm vibration syndrome for exposed miners.1-3 To reduce the vibration levels, a prototype of an antivibration handle was developed as part of a previous study.4 To provide some bench marking for this handle prototype and to follow the evolution of its performance over time, a test bench was developed to characterize the vibration emission values of jackleg drills under controlled operating conditions. As the current ISO 8662 series of standards could not apply directly to this type of tool, there was a need to design and validate a test bench to evaluate the vibration emission values of jackleg drills, while taking into account the conditions specific to the operation of this type of tool. Methods A test bench including an energy absorber, was developed for testing jackleg drills based on the ISO 8662-3 standard 5. The energy absorber was bolted to a 3300 kg concrete block to ensure tool stability. A pictorial view of the device is given in Figure 1. For validation purposes, acceleration measurements at the handle of a conventional jackleg drill were taken simultaneously along the three axes (xh, yh and zh) in an underground rock drilling operation as well as on the test bench. The handle accelerations were measured for three different jackleg angles (13º, 28º and 43º) determined with respect to the floor. Moreover, each measurement was repeated at least three times to asses the data repeatability. [ ] Results As a preliminary validation of the test bench, Figure 2 provides a comparison of the frequency weighted rms acceleration spectrum measured along the zh-axis, for both underground drilling and operation on the test bench (28º jackleg angle in both cases). It is shown that the vibration measured on the handle of a jackleg drill operating on the test bench is representative of that recorded during typical rock drilling operations, despite the fact that some harmonics of the percussion frequencies are generated with a higher amplitude on the test bench. Table 1 provides

Jan 6, 2006

By J. Kern, M. Cain, T. Torries

Until recently, the generation of electricity was regulated in all states and the value of generation assets in a regulatory environment for ad valorem taxation were based largely on the book value of the plant plus the rate of return on capital allowed by the state regulatory agency. This method of appraising utility generation assets is inappropriate in a competitive environment because past capital expenditures are not relevant in a competitive environment. However, it is not clear what valuation methods are appropriate after restructuring. This paper identifies key problems and advantages of other appraisal methodologies and makes comments on various valuation and taxation methods.

Jan 1, 2001

This publication is provided on an "as is" basis without warranties of any kind, either expressed or implied including, but not limited to warranties of title or implied warranties of merchantability of fitness for a particular purpose. The information contained in this publication is for general information purposes only. It does not constitute professional, technical, financial or other advice to the user of this publication and must not be relied upon as such by any person whatsoever. The use of this publication is at the users own risk. The authors/creators of the information contained in this publication have tried to ensure that the information contained herein is correct, but errors or inaccuracies may exist or the information may be incomplete, unreliable or no longer up to date. Therefore, no warranties of any nature whatsoever are given and any liability to any person in respect of anything and in respect of the consequences of anything done or omitted to be done, wholly or partly in reliance upon the whole or any part hereof, are disclaimed, including and without limitation any contractual, dialectal, direct, consequential or financial damages or losses. On no account will Organisers and/or any of the contributors or any person or entity involved in creating, producing or distributing the information and or software available in this publication be liable for any such damages arising out of the use of or inability to use this publication. Copyright Reserved The South African Institute of Mining and Metallurgy P O Box 61127, Marshalltown 2107, South Africa www.saimm.co.za All rights reserved. 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 written permission of the copyright owner. Although the greatest care has been taken in the compilation of the entire contents, the editors and publishers do not accept responsibility for errors or omissions. First Edition Copyright February 2004 Proceedings ISBN: 0-9584663-5-1 (1 volume and CD-ROM)

Jan 1, 2004

By A Bouazza, J Kodikara

In this study, 23 samples of leached ash (LA) were collected from an ash pond at Loy Yang Power Station and geotechnically characterised. The samples were collected at various depths and locations within the ash pond on two separate occasions in order to account for the full variability. The LA within the ash pond at Loy Yang Power Station (LYPS) was found to vary in texture from silt to sand, depending on the location from where the sample was collected. Samples collected near the ash pond inlet discharge point, for instance, contained more than 50 per cent sand sized particles and were subsequently classified under the Unified Soil Classification System (USCS) as silty sand (SM). Further downstream of the inlet discharge, the LA became progressively finer and was classified accordingly as elastic silt (MH) when the sand content became less than 50 per cent. Basic geotechnical testing revealed that the LA from Loy Yang Power Station was generally acceptable as a landfill cover material. The permeability of LA, however, was generally too high for prescriptive covers, (ie resistive covers that generally rely on the impervious nature of the material to control percolation). Alternative covers, generally rely on the store/release function of a capillary or monolithic barrier to prevent percolation into the landfill. Subsequently, a material that can maintain a high water storage capacity while at the same time, readily allow infiltration and evapotranspiration is required for an alternative cover. Sandy silt and silty sand are optimal soils for alternative covers, as they do not yield water to gravity forces, but do give up most of the water in their pores when subjected to high-matric suction (Kavazanjian, 2001). The effectiveness of alternative covers is ultimately assessed using computer models, such as UNSAT-H and HYDRUS-2D, to rigorously perform water balance calculations. Prior to using a computer model to determine the highest possible percolation in the worst climatic conditions, it is necessary to select the most appropriate materials. This paper suggests a method to screen available materials for use as an alternative cover material on the basis of the soil water characteristic curve (SWCC).

Jan 1, 2003

By T O&apos, Sullivan

Reconciliation of metal production from a sublevel cave (SLC) mining operation is a complicated process. SLC reconciliation is unlike reconciliation for open stope operations, where a tonnage of extracted ore can be assigned to an exact volume of in situ ore, and a direct comparison made between the estimation of contained metal and actual metal production. In SLC operations the ore extracted from a particular SLC drawpoint will be composed in part from the parcel of freshly blasted in situ material, in part from varying components of ore material (from cave stocks) flowing down from other previously mined areas vertically above the current draw position and in part from external dilution. This leads to difficulties in reconciling production grades against estimated grades. The problem is that we know how much metal we have produced but we can not precisely say where it has come from. Metal production reconciliation is fundamental in assessing ore reserve estimation accuracy and performance and in determining a draw management strategy for SLC mining. In terms of contained metal, differences in extracted metal compared to in situ metal represent changes to cave stocks. To generate local estimates of the cave stocks, differences in metal for each ring are treated as additions to or subtractions from a series of vertical columns of stocks extending throughout the height of the cave. The sum of metal differences (extracted versus in situ) for each vertical column results in a residual metal map at any particular mining level. The metal maps show areas where the metal production has been greater than or less than expected. The maps also highlight areas in the cave where residual metal is located, areas where targeted overdraw can reduce cave stocks.

Jan 1, 2006

By H. A. Taylor

Graphite is elemental carbon that crystallizes in the hexagonal system as six-sided platelets. It occurs naturally and is mined. And it can be made artificially from petroleum coke in the form of shapes (electrodes) and powders. The market for most kinds of graphite in most end-uses was good in 2004. The 2005 graphite market looks positive. The major graphite prices, as given in Industrial Minerals, remained unchanged throughout the year. The preliminary 2004 U.S. Geological Survey (USGS) prices for natural graphite showed almost no change for crystalline flake. They were $600/t ($544/st) in 2004 and$622/t ($564/st) in 2003. Mexican amorphous graphite was almost unchanged at $150/t ($136/st) in 2004 from$152/t ($138/st) in 2003.

Jan 1, 2005

By Phillip Martin Warren

Safety and productivity are critical factors in the performance of the Australian Mining Industry. In this sense, the paper point out that while the multiple dimensions of both training and productivity make it difficult to quantify the relationship, it is clear from this study that organizations that conduct training consider that there is a very positive link. Training is seen as a very important activity by the vast majority of organizations surveyed, and is an activity from which they consider they are gaining significant, and often very substantial productivity benefits. Therefore, it predicts well for productivity of Australian enterprises which invest in training.

Sep 13, 2001

1. A total of 14,413 mining operations reported employment to the Mine Safety and Health Administration (MSHA). Nearly half (48.9%) were sand and gravel operations, followed by stone (28.5%), coal (14.7%), nonmetal (5.7%), and metal mines (2.1%). 2. Mine operators reported 240,000 full-time equivalent workers1 (down 3.9% from 1999). Independent contractors reported 42,000 full-time equivalent workers working on mine property (up 8.6% from 1999). Coal operators accounted for 26.8% of reported employee hours, followed by stone operators (25.9%) and sand and gravel operators (12.1%). 3. Eighty-four (84) work-related mine fatalities occurred in 2000 compared to 90 the year before. •The mine fatality rate was 29.8 per 100,000 full-time equivalent workers compared to a fatality rate of4.6 per 100,000 employees for all private industry. •Thirty-one percent (31%) of the fatalities occurred in underground work areas, which account for only17% of total employment. •Although the largest number of fatalities (28) occurred among miners who work for coal operators, coal contractor employees had the highest fatality rate (61.1 per 100,000 full-time equivalent workers). 4.There were 10,839 nonfatal lost-time injuries reported to MSHA, occurring at a rate of 3.8 injuries per 100full-time equivalent workers, and resulting in a total of 417,918 lost workdays.2 •Among all employees,3 the highest injury rate occurred among coal operator employees (5.6 nonfatal injuries per 100 full-time equivalent workers). •The highest percentage (34.7%) of nonfatal lost-time injuries were due to handling materials (e.g., over-exertion in lifting, pulling, or pushing objects), which also accounted for the greatest percentage of lost workdays (29.3%). •Among the most frequently occurring injuries, the most severe (as measured by the median number of days lost) were associated with accidents involving falls of ground, the use of powered haulage, and slips or falls. •The most frequently reported part of the body injured was the back (22.9% of all injuries). Back injuries accounted for the highest percentage of lost workdays (21.6%). 5.Seven hundred sixty-seven (767) cases of occupational illness were reported to MSHA. •The most frequently reported illness was repetitive trauma, resulting in joint, tendon, or muscle inflammation or irritation (37.3%). •There were 155 (20.2%) illnesses reported as hearing loss. The majority (68.4%) of hearing loss cases occurred among surface workers. •Coal workers' pneumoconiosis accounted for 14.5% of reported illnesses.

May 15, 2002

By D P. Blair

There are two major aspects to wall control blasting – the potential for any blasthole to cause wall damage and the potential for a delayed sequence of blastholes to cause damage. The damage potential of individual blastholes is governed by standoff distance and charge weight. However, for locations sufficiently close to a highwall, dynamic finite element models and field measurements show that there is also a critical nature to those blastholes very close to the wall, over and above standoff distance. At many mine sites, the charge weight/standoff-distance is set by trial and error. Thus, a significant aspect of the present work is the determination of dynamic stress radiating from a blasthole. Unfortunately, the modelling and measurement of this dynamic stress is still faced with many difficulties. Typical models have questionable aspects, which casts serious doubt over their predictions, and it is shown that the Hustrulid Bar experimental technique does not correctly account for stress wave attenuation in extended media. In an attempt to solve the dynamic stress problem, the present work describes a model based on an exact solution under the assumption of viscoelastic material. The model takes full account of the rock mass elastic/viscoelastic properties, the explosive type, geometry and primer location and predicts a dynamic stress for direct comparison with the unconfined compressive strength of the local rock mass. This model predicts the standoff distance required to avoid damage due to a single blasthole. The behaviour of a delayed sequence of blastholes is analysed using an upgraded waveform superposition model, covering a range of initiation delay combinations, which predicts the peak particle motion (PPM) induced in the wall for each combination. This approach shows that there is no need to fire dedicated trim shots close to walls; all that is required is a carefully modified production shot. The mechanism of vibration screening is discussed, and its use in a superposition model highlights the potential of reverse firing (shield blasting) to reduce wall PPM. A conceptual model is also introduced to give a further insight to vibration screening and damage (via ground heave). This model predicts that a centre-lift blast will have a central heave profile and that a reverse-fired shot will produce a smaller power trough than that produced by a standard shot. It is demonstrated that the mechanism of presplit formation is not well understood; nevertheless, experimental evidence shows that presplits can be an effective method for reducing wall vibrations.CITATION:Blair, D P, 2015. Wall control blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 13–26 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By B Vorster

Falls of Ground is one of the highest causes of incidents, accidents and fatal injuries in our mines today. These falls of ground may occur as soon as the face is exposed after blasting or after machine cutting. The falls of ground can also occur after support has been installed. There are many reasons why these falls occur before and after supporting of the face. It is therefore important to support the exposed face as soon as possible to prevent the falls of ground. It is also very important to support the face with the correct support products and to support the face as designed and required by the mining engineers. The possible reasons for falls of ground, possible support methods and the products available will be discussed in this presentation. In typical conventional narrow vein stoping operations, the use of conventional temporary support components to offer some support to workers, whilst the permanent and generally more elaborate support system gets installed or constructed, still results in injuries to people. The author wishes to discuss the following items in this paper:- ? Introduction ? Basic face behaviour after exposure ? Controllable Parameters ? Mining Engineers support designs ? Primary and Secondary Support ? Products available for prevention of falls of ground

Jan 1, 2008

By Alfred Bodenlos

"El presente texto señala los acontecimientos geológicos en la Cordillera Negra y la deposición de travertino por las fuentes termales todavía activas al oeste de la población de Ticapampa. Los minerales fueron depositados principalmente como rellenos de fisuras, siendo cavernosos y en partes bandeados y sus temperaturas conocidas de formación varían desde baja hasta moderada, lo cual, además de su textura porosa, sugiere que están comprendidos entre las clases epitermal y mesotermal, según sistema propuesto por Lindgren. "

Sep 1, 1957

By Dean S. Rogers

The conventional role of exploration, development and grade control is examined in this paper within the context of the many and varied types of gold occurrences which are found at the Dome Nine. The account endeavours to trace the development of the total ore evaluation process, from diamond drilling through the exploration and drifting stage, to the stope development and planning phase of the operation, with an emphasis on sampling techniques and assaying procedure. The concept of ore reserve calculations is developed and the practice of grade control is described. In summary, the role of the geological, the engineering and the mining department is presented in relation to the contribution each has to make in the evaluation and exploitation of ore from one of the world's classic Archean gold deposits.

Jan 1, 1984

By G W. Clamp

The most traum atic event within the lUK coal industry during the last 30 years was its privatisation. Who were the relatively unknown people from RJB: white knights or robber barons? This paper highlights the strong safety and progressive engineering cultures th at existed and continues within the company. A long-term view of the business coupled with proven professionalism is amply developed. Quite dearly, to revert to private ownership is not a return to Victorian values but ‘back to the future’.

Jan 8, 1997

By William I. Nissen, Richard Havens

Continuous flotation studies were made at a 50 - lb - per - hr feed rate to confirm the effectiveness of a batch - scale procedure for concentrating phenacite and bertrandite minerals from Mount Wheeler ores that contained , in percent , 0.47 , 0.78 , and 4.7 BeO . The procedure for selective froth flotation of the beryllium minerals from a gangue composed chiefly of calcite , fluorite , and mica comprised closely controlled preconditioning with sodium fluoride and sodium hexametaphosphate in a series of small mechanically agitated tanks and use of a mixture of oleic acid with kerosine , fuel oil , or turpentine as a collector . It was difficult to adapt the laboratory flotation procedure to continuous operation . The principal problem of achieving adequate conditioning to depress calcite and fluorite ultimately was resolved by conditioning in series . Thereafter , three ore samples of different grades treated on a continuous basis yielded concentrates containing from 12 to 25 percent Beo from these relatively complex and difficult ores . Recoveries , on a BeO basis , ranged from 75 to 88 percent . Losses , which primarily were due to incomplete liberation , probably could be lowered in a commercial operation .

Jan 1, 1964

By Thales Lima Da Silva

As cerâmicas avançadas estão em diversas aplicações técnicas devido à possibilidade de melhoria na tenacidade, ao desgaste e corrosão em altas temperaturas. Neste trabalho avaliou-se o aditivo de sinterização Nb2O5 em teores de 0,2%, 0,4% e 0,6%vol. no compósito 98,5% Al2O3 com dispersão de 1,5% de ZrO2 nanométrica. Os pós foram misturados em moinhos de bola e as amostras foram conformadas por prensagem uniaxial. Utilizou-se a sinterização convencional a 1450ºC, 1500ºC e 1550ºC por 1 hora, caracterizando-se a densidade aparente pelo método de Arquimedes e a microestrutura final por microscopia eletrônica de varredura, procurando-se avaliar o efeito inibidor de crescimento de grão da zircônia frente a possibilidade de formação de fase líquida pela adição de nióbia.

Oct 30, 2017