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By Robert L. Kranz

The U.S. Bureau of Mines (USBM) has been monitoring and studying seismic activity associated with mining in the Coeur d'Alene silver district of northern Idaho. New statistical methods of studying the stope-scale (1-to l00-m) seismicity at one Idaho silver mine are used in this report (part 1) and its companion (part 2). This report deals with methodology and its limitations. The recent concept of fractals and their seismological use is discussed and applied to mining-induced seismicity. Three types of fractal studies are addressed: spatial analyses (including temporal changes of spatial patterns), temporal analyses, and size analyses. Other statistical measures of mine seismicity are also addressed: event mean location, inter-event distance distribution skewness, temporal coefficient of variation, nearest neighbor and next event statistics, and event location planarity patterns. Each of the methodologies discussed (fractal and nonfractal) is presented using sample data from two stopes in the mine. It is shown that stope-scale, mining-associated microseismicity has a fractal nature. The usefulness of demonstrating fractality (scale invariance) for predictive or descriptive purposes depends on recognition of the factors affecting the calculation of fractal dimensions. Several methodological traps are illustrated that can lead to an incorrect conclusion.

Jan 1, 2010

Researchers, medical organizations, statisticians, and others often use data on the nature and rate of occurrence of occupational diseases in directing their efforts and plans. Very often this information is developed from the reports of the States which describe the nature of work¬men's compensation claims and awards and the frequency with which they are made. To be meaningful, the statis¬tical information must be viewed in the context of the State laws involved. There is considerable variation among the laws of the different States. The Bureau of Mines has responsibilities for protecting the health of persons employed in the mineral industries and for the development of useful mineral products. To assist the Bureau in the accomplishment of its objectives, this compilation has been undertaken. For the benefit of the mineral industries, and any others who may have a similar interest, this volume is made available. An earlier compilation of the Bureau of Mines on this subject was published in 1952.4 However, during the intervening years, sufficient changes have been made in State laws to warrant completely recompiling the information. This publication includes the laws of the States, the District of Columbia, Puerto Rico, and the Virgin Is¬lands through 1964. Only those portions of the workmen's compensation laws which apply to or as ' related to occupational diseases are presented, and in each case enacted additions to and deletions from the basic law have been incorporated into the text of the law, thus snak¬ing it unnecessary to search out the various amendments made each year.

Jan 1, 1967

By R. A. Isberg

This report describes the design and implementation of UHF radio and closed-circuit television systems in the Black River room and pillar limestone mine near Butler, Pendleton County, Kentucky. Prior to designing the radio system, measurements of signal attenuation on 812 and 466 mHz were made in the slope tunnel and in the straight and level crosscuts in the mine. Two distributed antenna systems fed by two sets of base stations provide approximately 75o coverage of the mine. Passive reflectors are used for extending signals into intersecting crosscuts and two-way signal boosters will be used to extend signals to the perimeter and obstructed areas of the mine. Fourteen mine vehicles were equipped with mobile radios equipped with digital identification, alarm and status encoders. Fifteen portable transceivers also were used. Six closed-circuit television cameras provide surveillance of critical transfer points of the belt conveyor system, and the loading dock at the base of the slope and an ash disposal area in the mine. Two-way radio communication and closed-circuit television have saved considerable man. hours, increased production, reduced maintenance costs and enhanced safety. Innovative developments were the use of passive reflectors and two-way signal boosters for extending signals into intersecting crosscuts, development of lightweight signal margin measuring equipment, modifications of mobile digital encoders to automatically send status information from mine vehicles such as numbers of loads of ore delivered, hot engine, etc., and the use of CATV technology for multiplexing audio, digital and video signals onto coaxial cables from the surface to the mine.

Jan 1, 1981

By A. K. Majumder

In an effort to test the extent to which fundamental fluid mechanics can provide a prediction of particle separation, a study on a simple parallel-sided sluice has been carried out using glass bead and ilmenite mixtures at various particle concentrations and flow rates. Great care was taken to devise a flow splitter at the end of the sluice that permitted accurate measurement of the fluid flow profile and collection of slurry samples, allowing evaluation of the particle species concentration profiles. The actual particle separation taking place was compared to predictions made by first describing the fluid flow by a modified ?law of the wall? model. The hydrostatic pressure variation in the flow was taken into account and the eddy viscosity was calculated from a mixing length expression incorporating Van Driest?s damping function. Using an average density and viscosity provides an explicit expression for the velocity gradient that can be numerically integrated for the flow profile. The particle concentration distributions were then modelled with Hunt?s sediment transport model assuming the particle eddy diffusion coefficient to be the same as that for the water. Hindered settling velocities of the particles were calculated using Brauer and Thiele?s formula, which takes the particle size and density distributions and solids volumetric concentration into account. The resulting predictions of particle separation are shown to be a strong function of the settling velocities of the particles used. Keywords: flowing film concentrators, fluid velocity

Sep 1, 2012

By P. A. Cox

The purpose of the initial research performed under this contract was to determine the margins of safety in explosion-proof (XP) enclosures, which were designed and certified according to the current schedule (Schedule 2G). Results from this work provide baseline data on the current schedule, from which a new schedule can be formulated to give equal or greater levels of safety. Results and discoveries in the initial work led to an expansion of the contract to cover, additionally, weld quality in enclosure fabrication, reliability of enclosures with windows and lenses, and performance tests for enclosure qualification. Finite element calculations and hydrostatic tests revealed wide variations in the margins of safety in the enclosures studied; however, only one enclosure had a safety factor which was less than one. Results from a weld quality survey led to the recommendation of AWS Welding Standard D14.4 for the fabrication of XP enclosures. Based on other work, accelerated aging tests were recommended for qualifying plastics and adhesives that are used in some enclosures, and a Structural Performance Test was developed to test enclosure strength for a minimum static pressure of 150 psig.

Jan 1, 1982

By P. B. Leavenworth

Development in the Upper Texas Gulf Coast during 1945 resulted in the discovery of 23 new fields; one Miocene, eight Frio, three Cockfield-Yegua and eleven along the Wilcox trend. The Wilcox trend appears to he the most active at this time. Producing depths of the new Wilcox discoveries range from 2050 to 10,050 ft. Drilling along the Frio trend has been, for the greater part, projected to the deeper downdip sands. Eighteen of the new discoveries are classified as oil or condensate and five are gas discoveries.

Jan 1, 1946

By Robert J. Shank

This paper describes the Federal Government assistance available for northern mining development. The paper commences with a discussion of why the Federal Government should give assistance to northern mining development. It then uses a hypothetical case of a company which has a property it wants to develop to list the sectors within the . Federal Government that would have to be consulted in order to obtain federal financial assistance. The paper also outlines the type of information a company must be willing to provide the government in order to qualify for such assistance.

Jan 1, 1978

By R. L. Unger

Restricted fields of vision are a common problem with underground mining equipment. Also, when lighting systems are provided, they may be positioned where they cause glare. This restricts the visibility around the machines even further. To help address these problems, the U.S. Bureau of Mines has developed a PC based software package to aid in the analysis of certain human engineering aspects of mining equipment design. The software is available for use by equipment manufacturers and mining companies for design work on new machines, as well as for evaluating proposed modifications to existing machines.

Jan 1, 1994

By F. Mielli

Ranging between 20% and 40% of the typical mining operational costs, energy in mining operations is a growing concern for the industry. However, this concern is a complex, multi-faceted variable that involves government regulations, societal pressures, cost and competitiveness. A mining company successful in energy efficiency is becoming the standard of a successful company. The suggested energy strategy in mining and mineral processing operations has to follow a well structured approach that entails the following: ? Understanding where energy is being used and why, ? Recommending and implement energy conservation measures, ? Driving visibility to targets and results, ? Leveraging the energy spend across the enterprise, ? Developing a robust energy and sustainability strategy.

Jan 1, 2012

By James F. Reynolds

Introduction There are 1.4 Gt (1.5 billion st) of recoverable coal under less than 914 m (3,000 ft) of cover in Colorado in pitching seams. Snowmass Coal Co., in cooperation with the US Department of Energy, introduced the longwall mining method in pitching seams to North America. This venture is a coal mining research program directed toward the profitable production of coal under difficult mining conditions as found in pitching seams of the western US. Snowmass Coal classifies pitching seams into the following categories for longwall on the strike in seams 3 m (10 ft) or less thick: • Flat = 0 to 10°: Normal continuous mines and shuttle cars work efficiently. • Slight = 10° to 22°: The maximum pitch that rubber tired equipment will function. • Moderate = 22° to 40°: The angle of repose of mined coal. • Steep = 40° to 60°: The limit of safe use of this roof support. • Vertical = over 60°. The longwall roof support covered here will work in all pitches except vertical. The shearer and conveyor will work in flat through moderate conditions. Longwalling across strike with this equipment in seam pitch over 60° could be accomplished with an inclined face. Development of the first longwall panel began in 1979 and was completed in 1981. The longwall equipment was installed and mining began on Aug. 11, 1981. Mine Planning and Development The original mine plan took advantage of old works abandoned in the 1960s. The gates were developed on a two-entry system with the entries rising 2° to the strike, allowing water to drain from the face. The mining method was by Alpine F6A road header continuous miners with bridge conveyor type coal transport into 5.4-t (6-st) bottom dump coal cars hauled on 1.1-m (42-in.) gauge track by 7.2-t (8-st) battery locomotives. The initial concept was to haul coal from the longwall by battery locomotive. Lack of discipline, however, was shown in the irregular direction of the gate entries, and local rolls in the coal seams severely limited the capacity of battery locomotives. Current mining law prohibits using an intake escapeway for belts or trolley locomotives. A two-entry system is the simplest method of panel development in a pitching seam. A continuous miner cannot be trammed from one entry to another because of steep "X" cuts. Thus, the development requires a continuous miner in each entry. The configuration of the old mine works resulted in a first panel longwall block of three 108 m x 1.6 km (355 ft x 5,400 ft). In panel development, the use of battery locomotives for coal hauling became evermore costly. When the panels were completed and the setup room finished, the lower gate entry was changed to a belt entry and battery locomotives were abandoned. A new slope was driven and the mine supply system was converted to rubber tire diesel supply. The latest generation of roadheader and standard high powered shuttle car-to-belt system is now used for development. Selection of Longwall Equipment Longwall mining across the strike on pitching seams is currently practiced in many nations. Equipment similar to that used by flat seam longwalls is available for pitching seam use in Great Britian and Germany. Face equipment includes a twin outboard armored face conveyor. It was selected to give maximum retention of coal on the conveyor due to flight rigidity and to prevent coal from sliding down the face and jamming the lower belt gate. Also selected was a 22-mm (0.9-in.) Dowty twin-outboard face conveyor for a 106-m (350-ft) face with a single 112-kw (150-hp) drive

Jan 12, 1983

By S. H. Ash

NINE-TENTHS of the total anthracite deposits of North America are in Pennsylvania. Corrosion of pumping equipment by acid mine waters has been experienced at tremendous cost by mining companies in the anthracite region of Pennsylvania, for many years in many ways. The design and specifications of the large centrifugal pumps as provided in the proposed mine-drainage system (7-35, 45, 46, 48, 54, 64, 70, 71)° make it imperative that a metal or alloy be recommended that has the highest corrosion resistance and, at the same time, acceptable properties suitable for general workability (welding and machining). This report presents data on the corrosive and erosive effects of acid mine waters in the anthracite region on metals and alloys for pumping equipment and drainage facilities necessary to remove or control this water.

Jan 1, 1955

By A. Monomakhoff

If a conductor traversed by an electric current is broken, a conduction forms in the air between the two broken ends of the wire. This conduction manifests itself in an initial phase by an electric spark and, in a second phase, by an arc if the the circuit continues to supply sufficient power. This arc goes out when the distance between the two ends of the conductor becomes sufficiently large. If the break occurs in an explosive atmosphere, the energy contributed by the arc can cause an explosion. To avoid such accidents, electric circuits that may be utilized in hazardous atmospheres can be made "intrinsically safe". The investigation which we conducted is part of a research project on the intrinsic safety of arcs of high intensity but short duration, in the case of resistive circuits. We developed an electronic system which makes it possible to limit the duration of an arc at the level of the break of a conductor traversed by a current with a possible maximum intensity of 80 amperes. This experimental device for monitoring and measuring the parameters of the arc has shown that arcs of high intensity but with a duration limited to a few microseconds do not ignite an explosive methane-air mixture.

Jan 1, 1975

By L. D. Tracy

Many bituminous coal-mining companies have inaugurated extensive safety programs, but the failure to have approved or permissible equipment or safe practice in only one part of a mine has resulted in disaster. The necessity of using only equipment bearing the U. S. Bureau of Mines approval plate is emphasized by the fact that many accidents are the direct result of carelessness on the part of trusted employees using non-permissible equipment. A concrete example is found in the case of an explosion on October 26, 1926, in a mine in the Pittsburgh district, Pennsylvania. Story of the Explosion At about 10 o'clock on the night of the explosion an examination was made in No. 2 butt left and parallel off No. 14 north, and was found to be clear of dangerous accumulations of gas. (See figure). Several hours later a crew of two men brought a self-propelling rock-dusting machine within 50 feet of the face of No. 2 butt parallel before they examined for gas. The machine operator found an accumulation of explosive gas about 13 inches from the roof. He began to wave his arms thoroughly mixing the gas and air. Undoubtedly a highly explosive mixture was created, and as the men attempted to run the machine back to fresh air as explosion occurred.

Jan 1, 1927

By K. E. Stanfield

This report presents the results of analytical studies made on two series of oil-shale samples from the Mahogany ledge of the Green River mine the character of the various grades of oil shale that are being mined and processed into shale oil and refined products at the Bureau of Mines Oil-Shale Demonstration Plant at Rifle, Colo. The analytical work was part of a synthetic liquid fuels program being conducted at the Petroleum and Oil-Shale Experiment Station, Laramie, Wyo. The 16 oil shales ranG6d in color from a gray brown ( or a sample that assayed 10.5 gallons of oil per ton to a very dark brown for a sample that assayed 75.0 gallons of oil per ton. In general, the samples were similar as to the types of organic and inorganic matter that they contained but varied widely in the amounts or these constituents. The principal constituents were calcite, dolomite, illite, and yellow organic material, while the minor constituents were quartz, feldspar and plagioclase feldspar, pyrite, marcasite, analcite, opal, black organic material, and small woody fragments. Some micro-fossils, spores and pollen grains were found also.

Jan 1, 1951

By J. A. Cox

The Ashanti mine is located within the Lower Proterozoic Birimian of Ghana, and covers a concession of 474 square kilometres at its Obuasi operations which comprise large scale underground, surface and tailings treatment facilities. The mine had operated for a century at the end of 1997 and had produced nearly 25 million ounces of gold, a significant proportion of which came from the underground operations. This paper covers the strategy under which exploration for both surface and underground mineral resources was instrumental in enabling the expansion programme to go ahead together with the methodologies and results that have developed in the exploration area over the last five years. Within capital expenditure constraints, the objective on surface is to replace oxide depletion with a secondary objective of discovering new sulphides in areas other than the main trend. In the underground, the exploration strategy is directed at replacement of both underground and surface sulphide depletion, minimising finding costs and assisting the development of long lead time infrastructure. The exploration application describes the methodologies in use for both surface and underground exploration that have been developed in recent years in conjunction with a description of a major review conducted in 1995/96 of the exploration database using an integrated approach, geochemistry, geophysics, remote sensing and structural geology. A revisit of soil geochemical data in particular, and modification of exploration methodology led to the success in finding relatively significant new oxides in 1997.

Jan 1, 1999

By Raja V. Ramani

Discussion in this section of the Handbook is limited to the working environment of miners, the mine workers themselves, and the machines used in mining (Fig. 11.0.1). The contents emphasize personnel health and safety aspects and engineering design and control practices to ensure a productive health and safety environment. Reference is to the health and safety of the individual miners as well as to the safety of the working environment. This Handbook also contains references to health and safety regulations in Chapter 3.2 and environmental protection in Chapters 3.4 and 7.3.

Jan 1, 2008

By George A. Miller

THE outstanding characteristic of the American business man is that he likes to run his own business his own way, without any interference from his wife, his friends, his bankers, and least of all from his government. The oil man, like the miner, is an American business man in which this special characteristic is even more pronounced. It may be because he has been an explorer and is more nearly like those pioneering Americans who explored, developed, and built these United States.

Jan 1, 1944

By Lenin Salazar Dulanto

La baja de precios en algunos minerales ha obiligado que las empresas mejoren su proceso productivo a través del uso de equipos de última tecnología en los procesos de mecánica, hidráulica, electricidad y electrónica, así como en la eficiencia en el corte y taladrado, extracción y transporte. Sin embargo, tanto el desatado y sostenimiento manual desarrollaron un estréss y desgaste de energía en el trabajador. En este sentido, el presente trabajo señala una nueva forma de realizar tales operaciones en el ciclo de minado de la empresa Milpo a fin de garantizar la seguridad física de los trabajadores y equipos.

Jul 31, 2003

By A. S. Bayne

THIS paper will present a review of the mining operations of one of Canada's most lately established gold mining districts (1). The history of the Little Long Lac and Sturgeon River areas is interesting in view of the fact that, although they have long been the scene of a certain amount of mining activity, they remained little more than an uninhabited wilderness until 1933, since which time ten producing gold mines and mills have been established in permanent operation, eight of these having entered production since the beginning of 1937. As complete a background as possible will be given concerning the major influences having a bearing upon living and economic conditions in the mining communities. The object, here, is to show the diversity of problems which demand the attention of the operator starting up and operating a new mine in present times, and to indicate the ways in which these problems are successfully met in this district. A description of the power facilities and plant equipment will be followed by a summary of the problems encountered and methods applied in exploration and development. This is to aid in forming a background showing the circumstances which influence the mining methods and costs of the various operations. The paper will conclude with a description of the mining methods used and the costs of the operations, including summarized analyses of the stoping methods and mining conditions. The various phases of operation will be dealt with separately, in so far as this is possible, in order to present clearly the salient features. It is necessary, however, that the reader bear completely and constantly in mind the fact that in actual operations these phases arc, to a large extent, intimately related and greatly affect each other, as well as being, in turn, affected by other circumstances beyond the control of the operator. A few of these circumstances are: capital available during the development period and early stages of productive operation; strength of rock comprising the ore and its boundary walls; grade, size, shape, and location of ore-bodies; and many other natural items which must be carefully weighed in relation to the details of operation.

Jan 1, 1940

By Bradley Stoughton

(Cleveland Meeting, October, 1912.) [SECRETARY'S NOTE.-To avoid repetition of foot-notes, references to authorities are made in this paper by means of figures, referring to a numbered list in the appendix.-J. S.] INTRODUCTION. THIS paper gives the results : first, of a research into the somewhat extensive literature of titanium; and second, of a series of original tests upon the effect of titanium on iron castings. New investigations have also been made upon the effect of titanium on steel, but I hope to treat this subject in an independent paper at some later date, and, therefore, will not discuss the experiments in detail here. The combined results of this study, which extended over a period of more than two years, can be briefly summarized as follows: 1. Steel or cast-iron, in which the titanium is properly proportioned, and which has been properly treated, is improved in strength, toughness, and durability against wear, such as, for example, the wear of railroad-rails, of steel and chilled-iron .rolls, car-wheels, etc. 2. These improvements seem to be caused, not so much by the direct effect of titanium on the metal, as by its cleansing influence in removing harmful impurities, such as oxygen and oxides, nitrogen, occluded slags, and perhaps also sulphur. It appears also to reduce segregation, which would contribute to the same end. 3. In order that its effects may be fully realized, the treatment of steel or iron with titanium must be correctly performed. There are a few simple, but essential, details to be observed; if they are neglected, the best results cannot be expected. To illustrate by an example : A series of tests on cast iron

Nov 1, 1912