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By V. B. Achanti, A. W. Khair

Laboratory studies were carried out at West Virginia University to investigate the rock fragmentation mechanism by continuous miners using an automated rotary cutting simulator. The primary factors influencing the fragmentation process were found to be: bit spacing, bit geometry, depth of cut and cutting drum rotational speed. This paper presents the influence of these parameters in achieving optimum energy consumption and minimizing dust generation during rock fragmentation process. Tree bits were used simultaneously on Indiana limestone while the bit tip angle was varied from 60° to 900. Bit spacing was varied from 2.54 cm (1 in.) to 5.08 cm (2 in.) while the cutting process was assessed for varying cutting depths. Restorable dust generated during the course of the experiments was analyzed utilizing cascade impactors. Assessment of these parameters has led to a better understanding of the cutting mechanism by continuous miners in terms of energy consumption and dust generation.

Feb 24, 1997

By Franco Oboni, Iain G. Bruce

The design of tailings containment structures relies on well-understood engineering methods being applied consistently. Unfortunately, not all facilities are designed or managed to the same level of competency. To standardize procedures, the Mining Association of Canada (MAC, 1998) prepared a “Guide to Tailings Management.” It recommended review of designs and an assessment of the risks associated with tailings impoundments be implemented during all phases of amine life. This paper describes how the quantitative risk assessment (QRA) process can be used to define risks associated with the design, construction and operation of a tailings management facility. And it discusses how, once the risk tolerability curves (RTC) are defined for a project, they can assist the risk management (RM) process.

Jan 1, 2002

By CLARENCE WM. POY

THE most common difficulty faced by an engineer or mine operator when opening a new property in a new field is the lack of roads and of cheap transportation. This one item often swings the balance of success or failure in starting a project. In Alaska, as elsewhere, such problems are more or less serious. In the boom days around the Valdez district, as well as in other parts of this territory, freighting was accom¬plished by dog teams or horses, or even by men that were willing to put their shoulders into harness, because there were virtually no roads. More important, there was only one time when supplies could be transported, and that was when there was suffi¬cient snow on the ground following a heavy wind. Then, and only then, could one depend on the snow to support horses and sleighs, and be sure that the gulleys, streams, and crevices in the glaciers were filled with snow to avoid pitfalls. These methods were used when one had no roads, no streams in the summer to float a barge, or even a trail for a pack train. If the snow was deep and soft, trans

Jan 1, 1935

By Craig Hartley

? A helper stands beside a continuous miner as the operator is at the controls. The operator means to push the stop button but hits the drum rotation start button by mistake. The drum begins to turn and the bits catch the helper's clothing. He is thrown violently to the ground and suffers multiple contusions. ? A farmer's wife helplessly watches her husband drawn into the claws of farm machinery while she frantically and unsucessfully searches for the control to stop the machine. ? A mechanic on the night shift replaces plugs in the lubrication systems of all three engines of an airliner following routine maintenance. In doing so', he fails to notice that "0" ring seals have not been mounted on the plugs. A few hours later, as the fully loaded airliner is cruising high over the ocean, oil pressure on one engine drops precipitously. The pilots quickly shut down the engine and turn for home. Almost immediately, the two remaining engines lose their oil and fail.

Jan 1, 1983

By H. Copur

Experimental studies for quantification of force and brittleness indices relevant to rock cutting performance are presented. A simple interpretation method is developed, which quantifies the force-penetration response obtained from indentation tests. Basic parameters of the quantification are force increment and decrementrates, force increment and decrement periods, and number of increment and decrement data points. Blocks of eleven different rock samples were collected from different operating mines in Turkey and subjected to indentation tests to calculate the indices. The samples included harzburgite, serpentinite, trona, limestone, claystone, two different sandstone samples, siltstone and three different chromite ore samples. The concept was validated by a set of full-scale linear cutting tests using a conical cutter for measuring the cutting performance in relieved and unrelieved conditions, i.e. cutter forces, specific energy, size distribution of rock cuttings. The rock cuttings were sieved to determine coarseness index, indicates coarse chip generation characteristics, and size distribution. The force index is moderately correlated with the cutting performance and mechanical properties of the rocks, and poorly correlated with the coarseness index and size distribution of cuttings. A general and moderate trend is observed between the brittleness index and the coarseness index, cutting performance for unrelieved cutting conditions and mechanical properties of the rocks. However, additional data is required to fill the data gaps and to potentially establish relationship between the brittleness index and all other parameters.

Jan 1, 2003

By Albert H. Fay

The first data compiled by the Bureau of Mines relating to coal- mine accidents in the United States were published in Bulletin 69," in which the total fatalities by years and States were tabulated from 1896 to 1912. Since the publication of Bulletin 69, further research has been conducted, with the result that the bureau is now able to publish for the first time all of the fatal accidents described in the State inspectors' reports by States, causes, and calendar years, from the beginning of inspection service to date. For the anthracite mines of Pennsylvania, there is a continuous record since 1870; the records of the Pennsylvania bituminous mines are continuous from 1877, and, with the exception of one year, the Ohio records are complete from 1874 to date. In fact, the records of all of the States, with few exceptions, are complete; and incomplete data for any year may generally be attributed to the fact that no report was published during that year. The magnitude of the coal-mining industry in the United States is such that too much stress can not be placed on the need of safeguard- ing the three-quarters of a million men employed. Although the figures given herein show an appalling record for past years, they are not published for the purpose of proclaiming the high fatality rate of the past. They are a record of experience covering a period of 45 years, showing causes and results of many accidents in the coal mines of the United States. They represent a diagnosis of the hazard of the mining industry, pointing out the principal physical causes of accidents, and make available a body of uniform facts that will serve as a basis of preventive measures for use in future operations. It is with these great purposes in view that the Bureau of Mines presents the classified data in this report. Classification and study of mine accidents on the basis of number of persons killed is common and very old, but fails to throw enough light upon the problem involved. Many serious accidents in mines have no fatal results, hence in a tabulation of fatalities they are overlooked and the real hazard of the industry is not made clear. An accident does not necessarily include an injury that may result therefrom. Such accidents as the breaking of a hoisting cable, an explosion of powder, gas, or dust, a runaway car or motor are all serious. Although no loss of life results, they should be recorded, investigated, and studied to prevent their repetition. No accurate data for the United States are available showing how far the personal element as related to the miner and his co-worker, the mine foreman, or to the superintendent and others in authority, contributes to accidents. Many accidents are due to inexperience on the part of the miner, his failure to heed orders, a misunderstanding of instructions and last, but not least, carelessness of himself or his fellow worker. A foreman or superintendent may fail to give proper warning regarding the conditions of certain parts of the mine; he may not have inspected certain rooms or entries on the day of a mine accident; the mine may not be properly equipped, or the operator may neglect to comply with the inspector's recommendations. There is, therefore, a personal element on the part of both the operator and the miner that must be considered. Legislation and the enactment of compensation laws will make the operator realize the seriousness of the mine-accident situation, when fatalities and injuries are to be paid for in legal tender of the realm. The miner must be educated and made to realize the dangers he encounters; he must learn that self-preservation and the safety of his fellow workmen should receive his first attention; he should cooperate with his employer, his asso- ciates, and the State mine inspector to the end that the mine hazard may be reduced to a minimum. "Cooperation for safety" should be the watchwords of the operator, miner, State inspectors, and all others in any way interested in the mining industry.

Jan 1, 1916

By Janet Torma-Krajewski

Research has shown that an ergonomics process that identifies risk factors, devises solutions to reduce musculoskeletal disorders (MSDs), and evaluates the effectiveness of the solutions can lower worker exposure to risk factors and MSDs and improve productivity. A review of the Mine Safety and Health Administration (MSHA) injury/illness database indicated that 46% of illnesses in 2004 were associated with repetitive trauma and 35% of nonfatal lost days involved material handling during 2001? 2004. Even though these statistics show that MSDs significantly contribute to occupational illnesses and injuries in the U.S. mining industry, few mining companies have implemented an ergonomics process. Despite the many unique challenges in the mining environment, three mining companies partnered with the MSD Prevention Team at the National Institute for Occupational Safety and Health?s Pittsburgh Research Laboratory to demonstrate that an ergonomics process could be systematically implemented and effectively integrated with existing safety and health programs. Because these three mining companies were very different in organization, culture, and size, the ergonomics processes had to be modified to meet the needs of each company. A description of how these three companies applied ergonomics and the tools and training used to implement their processes is given. Prior to discussing the case studies, general information on the elements of an ergonomics process is provided.

Feb 1, 2009

By Victor Romero, Steve Redmond

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. 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 individual authors and are not necessarily those of the SME. The mention of trade names for commercial products does not imply the approval or endorsement of SME.

Dec 1, 2011

By Claudio Asioli

"The project’s goal was to construct the Al Ghazala Intercontinental, a multi-use development in the bay area of Tripoli overlooking the Mediterranean Sea. The site of the project is located approximately 500 ft (150 m) from the Mediterranean coast, near the Al Ghazala roundabout in the town center of Tripoli, Libya. The investor of the project was Magna Properties Group, Ltd. – Libya, the main contractor was Man Enterprise S.A.L., and the design and construction management was performed by Dar Al-Handasah Engineering. Trevi S.p.A. was contracted to perform the design and construction of the anchored diaphragm walls and dewatering systems for the excavation of a two-level basement car park, which extends across the full footprint of the site.The site was approximately 640 ft by 230 ft (195 m by 70 m) in plan and nearly flat. The groundwater level typically varies from about 11 ft to 23 ft (3.4 m to 7.0 m) above mean sea level. To construct the required raft foundation, it was necessary to excavate the area down to El. -15.7 ft to -26.3 ft (-4.8 m to -8.0 m), which resulted in an excavation depth ranging from about 27 ft to 39 ft (8.3 m to 12.0 m) below the existing ground surface.Subsurface ConditionsThe subsurface site investigation was performed in three phases by Al-Tamier Engineering Consulting Bureau. During Phase 1, a preliminary investigation was undertaken during the early stages of the project to obtain information about the general stratigraphy and groundwater level at the site. Phase 2 was performed to obtain subsurface information and design parameters, and Phase 3 was performed as a supplementary ground investigation to investigate unexpected ground conditions identified during Phase 2. In total, 14 boreholes were drilled to depths ranging from about 80 ft to 180 ft (24 to 55 m). The generalized subsurface profile is quite heterogeneous, and is predominantly composed of sand with silt and gravel that is underlain by limestone, calcarenite and claystone"

Jan 1, 2017

By Claudio Asioli

"The project’s goal was to construct the Al Ghazala Intercontinental, a multi-use development in the bay area of Tripoli overlooking the Mediterranean Sea. The site of the project is located approximately 500 ft (150 m) from the Mediterranean coast, near the Al Ghazala roundabout in the town center of Tripoli, Libya. The investor of the project was Magna Properties Group, Ltd. – Libya, the main contractor was Man Enterprise S.A.L., and the design and construction management was performed by Dar Al-Handasah Engineering. Trevi S.p.A. was contracted to perform the design and construction of the anchored diaphragm walls and dewatering systems for the excavation of a two-level basement car park, which extends across the full footprint of the site.The site was approximately 640 ft by 230 ft (195 m by 70 m) in plan and nearly flat. The groundwater level typically varies from about 11 ft to 23 ft (3.4 m to 7.0 m) above mean sea level. To construct the required raft foundation, it was necessary to excavate the area down to El. -15.7 ft to -26.3 ft (-4.8 m to -8.0 m), which resulted in an excavation depth ranging from about 27 ft to 39 ft (8.3 m to 12.0 m) below the existing ground surface. Subsurface ConditionsThe subsurface site investigation was performed in three phases by Al-Tamier Engineering Consulting Bureau. During Phase 1, a preliminary investigation was undertaken during the early stages of the project to obtain information about the general stratigraphy and groundwater level at the site. Phase 2 was performed to obtain subsurface information and design parameters, and Phase 3 was performed as a supplementary ground investigation to investigate unexpected ground conditions identified during Phase 2. In total, 14 boreholes were drilled to depths ranging from about 80 ft to 180 ft (24 to 55 m). The generalized subsurface profile is quite heterogeneous, and is predominantly composed of sand with silt and gravel that is underlain by limestone, calcarenite and claystone."

Jan 1, 2017

By Euclid P. Worden

INTRODUCTION Today, conventional raise boring is an accepted method of development in underground mines and on major construction projects. Over the years that this technique, and its associated machines and tools, have been under development, many articles have been written on the subject. To a great extent, these papers have reported operating results of one or more specific projects or have been generalized reviews of state-of-the-art machines and tools. This paper is intended as a review of the technique from an operational standpoint. Conventional raise boring, as opposed to the related variants box hole drilling and underground blast hole drilling, is a two step process consisting of the pilot hole drilling and reaming cycles. This author has covered the subject of pilot hole drilling in another article (1) . A good review of the current machines and equipment has been presented by Monroe (2) and an overall review of this entire technology was published by E&MJ (3) and Mining Journal, April, 1983 (4) . The subject of the reaming cycle is presented here together with some of the technical aspects of how the drilling tools are intended to be used. OPERATIONS Bit Change After the pilot bit has broken through at the end of the pilot hole cycle, a changeover takes place at both the machine and

Jan 1, 1985

De acuerdo a los últimos trabajos realizados sobre la exploración en la mina Cercapuquio, se realizó un muestreo de la veta 53 donde se observó que en la caliza, más allá del ala norte, como en el lugar llamado Chaupirange, existe grandes depósitos de carbonado estático con siderita y limonita, en bolsa de erosión de la caliza normal. Asimismo, se describe otros métodos utilizados para la exploración geofísicadel subsuelo como los electromagnéticos e inducción. En ese sentido, se trata de crear un campo (primario) a través de una corriente eléctrica alterna (primaría) en un circuito. A este campo, es concadenada una corriente (secundaria) que circula en el cuerpo conductor mismo ( en general desfasada respecto de la primaria), que genera a su vez, un campo secundario. Este último se compone con el campo primario para formar un campo total, que está relacionado con la posición y naturaleza del cuerpo conductor que funciona de circuito secundario.

Jan 1, 1956

By R. V. Higgins

The Bureau of Mines investigated the use of electronic computers for obtaining more information about relative permeabilities of reservoir rock to oil and water. It was found that there are many possible combinations of relative permeability curves that will result in virtually the same recovery versus injection) but they require different times and rates to recover the oil even with different mobility ratios. Permeability curves obtained by the use of non-viscous oil and employed for calculating the waterfloods of viscous oils can lead to serious inaccuracies. For viscous oils) the wettability characteristics in the middle portion of the permeability curve affect recovery nearly as much as other portions of the curve; this) however) is not true for non-viscous oils in water-wet reservoir rock.

Jan 1, 1967

By Lawrence H. Van Vlack, Alfred S. Keh

The distribution of sulfur in iron was found to be dependent upon the time and temperature of the treatment as well as the chemical composition of the sulfide. With higher temperatures, the sulfide phase spreads more extensively between the iron grains. A complete network, however, does not form until approximately 1300°C (2372°F), ot which temperature the dihedral angle approaches zero. Silicon has little effect on this change. Aluminum, oxygen, and manganese all modify the temperature of sulfide network formation to a higher value. The microstructures which result and have significance in relation to hot-shortness are discussed. SULFIDE inclusions in steel were recognized by metallurgists before the turn of the century. Considerable attention has been paid to them, and numerous studies have been made on the working properties of steel as affected by them. It has been suggested that ho t-shortness of steel is due to the presence of an enveloping liquid sulfide film at the grain boundaries of the steel in the range of the hot-working temperatures. However, several facts have been observed in commercial steels which do not seem to be completely consistent with this explanation: 1) the frequent absence of continuous films of sulfide as observed under the microscope, 2) the absence of hot-shortness in some high sulfur and resulfurized steels, and 3) the limitation of hot-shortness to a definite temperature range. The role that manganese plays in steel to eliminate hot-shortness is well known, but the theory behind it is still under question. Moreover, the effect of de-oxidizers such as aluminum and silicon, and the effect of oxygen are still not clearly known. In this study, the effect of heat treatments and of additions of manganese, aluminum, silicon, and oxygen upon the distribution of sulfide inclusions in iron was investigated. Both the as-cast and the heat treated structures were studied, using microscopic and autoradiographic techniques. Part of the results were interpreted in terms of Smith's' concept of microstructure. Review of Literature Metallurgists used to consider sulfide inclusions as suspended particles. It was Wohrman' who first pointed out that sulfide inclusions are soluble in liquid iron. Many observed facts may be understood on the basis of this concept of solubility. Wohrman found that small castings contain small inclusions. and larger castings contain larger ones. Also, inclusion sizes are smaller near the chilled surface. For the same size ingot, the average inclusion size in a given heat of steel depends upon the rate of solidification. That is, with slow solidification, enough time for precipitation and agglomeration of these

Jan 1, 1957

By Ryan L. Veenstra

This paper presents a modelling study of a cemented paste backfill in an underground stope. The model was developed to help provide a better understanding of what is happening in the stope during the filling stage of the stope. In order to do this, the model incorporates the paste rise rate, stope geometry, and time-dependent input parameters. This paper looks at the effect of geometry in two parts. The first part compares a series of simple rectangular stope models. These models differ in size both in two and three dimensions. The second part compares the results of four 2D models together and then to the field instrumentation data. Part of this section introduces the geometry and instrumentation within the test stope.

Jun 1, 2012

By Matthew Preedy, Brett Campbell, Jim Rush, Alan Howard, Derek Penrice

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, 2018

By J. Durkin

The Bureau of Mines has conducted field studies in coal mines throughout the United States to determine the effectiveness of electromagnetic techniques in locating miners trapped underground following a mine accident. Data from these tests have been used to generate models of expected signal and noise distributions as found above these mines. These distributions have aided in placing the expected performance of a through-the-earth electromagnetic communications technique into a probabilistic framework. Results show that at a 10% false-alarm rate, the expected probability o detecting a miner's signal" from a depth of 1000 ft is 54% at 500 ft it is 95%. These depths exceed the actual depths of 90 and 50%, respectively, of United States coal mines. Sensitivity studies have shown that at depth of 1000 ft, the probability of detection will improve approximately 2% for each dB of increase in signal-to-noise (SNR) ratio.

By George S. Rice

The major purpose of this bulletin, as indicated in the preface by Dr. John W. Finch, Director of the Bureau of Mines, is to give a critical review of the coal-mining methods used in the principal producing countries of Europe, to describe the reasons underlying the adoption of these methods, and to contrast them with coal-mining methods employed in the United States. The report includes discussions of various subjects intimately related to coal mining, such as geology of the principal coal fields; production and resources of the several countries; mine safety and health research; Government mining regulations; mine inspection and rescue procedure; safety lamps; fixed lighting methods under-ground; testing electric motors, mining machines, and mining explosives for permissibility; and special mining hazards, such as explosions of gas and coal dust, mine fires, instantaneous gas outbursts, ground movement and surface subsidence, and bumps. Commercial, economic, and labor problems of European coal mining, including miners' output, wages, and social-insurance schemes, as well as cost of mining, prices of coal, etc., are briefly described. It will be noted that data on most subjects are not given for Russia, which has become an important coal-producing country, owing to the lack of reliable published information concerning Russian coal mining.

Jan 1, 1939

By R. W. Raymond

WISH to call the attention of the Institute to a curious subject, brought to my notice last summer by Mr. Begger, the accomplished metallurgist of the smelting-works of the Boston and Colorado Company at Black Hawk, near Central City, Colorado. At these works, the richest auriferous sulphhrets of Colorado (particularly copper pyrites) are smelted in reverberatories, together with roasted tailings (iron pyrites), and the gold and silver are concentrated into a new, artificial sulphide, or copper matte, containing $1500 and upwards of the precious metals per ton, and this is shipped to Swansea. I will say in passing, that this shipment of an unrefined product, like the similar shipments from Utah and Nevada to San Francisco, Chi¬cago, St. Louis, Newark, New York, and Europe, of crude argentiferous lead or "base bullion," is not a sign of incomplete metallurgy here, but has a sound business reason. The separation of the precious metals in the West would be more expensive, to begin with ; and then it would necessitate the movement of these metals by express, at high rates and risk, to commercial centres or coining mints, while the base metals having no home market, must be shipped and sold at little or no profit. At present, the gold and silver, safely packed, as it were, in the base metals, are transported with safety as ordinary freight; and the base metals probably more than pay cost of shipment and separation. To return to the Black Hawk reverberatories. On a recent occa-

Jan 1, 1873

By R. W. Raymond

I wish to call the attention of the Institute to a curious subject, brought to my notice last summer by Mr. Begger, the accomplished metallurgist of the smelting-works of the Boston and Colorado Company at Black Hawk, near Central City, Colorado. At these works, the richest auriferous sulphurets of Colorado (particularly copper pyrites) are smelted in reverberatories, together with roasted tailings (iron pyrites), and the gold and silver are concentrated into a new, artificial sulphide, or copper matte, containing $1500 and upwards of the precious metals per ton, and this is shipped to Swansea. I will say in passing, that this shipment of an unrefined product, like the similar shipments from Utah and Nevada to San Francisco, Chicago, St. Louis, Newark, New York, and Europe, of crnde argentiferous lead or "base bullion," is not a sign of incomplete metallurgy here, but has a sound business reason. The separation of the precious metals in the West would be more expensive, to begin with ; and then it would necessitate the movement of these metals by express, . - at high rates and risk, to commercial centres or coining mints, while the base metals having no home market, must be shipped and sold at little or no profit. At present, the gold and silver, safely packed, as it were, in the base metals, are transported with safety as ordinary freight; and the base metals probably more than pay cost of shipment and separation. To return to the Black Hawk reverberatories. On a recent occa-