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By Gerald T. Homce, Michael R. Yenchek, H. Kenneth Sacks, James C. Cawley

Accidents occur when least expected, from sources that we rarely anticipate and with outcomes that can vary greatly. Anyone who has ever been involved in an automobile accident knows, the transition from driving comfortably and safely down a highway to being involved in a potentially life-threatening situation can occur in a heartbeat. Accidents on the job are no different. The mining industry has a relatively small number of electrical injuries, compared to industries such as construction or agriculture, due to the small total employment in mining. Mining does, however, have one of the highest occupational electrocution rates of any U.S. industry, at 2.8 for every 100,000 workers per year. This is approximately four times the average for all industries. Data from the Mine Safety and Health Administration (MSHA) shows that 75 electrical fatalities occurred in the mining industry between 1990 and 1999. Of these, at least 17% involved high-reaching mobile equipment that contacted overhead power lines.

By Ronald S. Conti

This U.S. Bureau of Mines (USBM) report describes various fire-fighting resources available to the mining industry and examines the fire preparedness of four western coal mines. Information regarding fire-fighting equipment indicates that an inadequate maintenance program may cause component failure of fire extinguishers, damage to waterhoses is usually a result of improper care, and foam may be a convenient means of conveying water to the fire. Performance data relative to water nozzles (throw distance) and specific practices to improve the state of preparedness in many of these areas are discussed. Studies also indicated that a high-expansion foam plug, will travel down an entry, with a 1% rise in elevation, 207 m (680 ft) before a plywood stopping separating the generator and plug failed. The advance rate of the foam plug decreased when the entry is dry, requiring more foam concentrate and as the foam spread further down the entry. An examination of the mines showed state-of-the-art monitoring systems were common at the minesites. Fire safety was also stressed, including early detection and rapid response of the miners to evacuate the mine. However, the mines placed little emphasis on performance of water nozzles, or personal protective clothing for the underground firefighters.

Jan 1, 1994

By Frederick W. Lee

List of contributing editors of Geophysical Abstracts:

Sep 1, 1932

By C. H. Schack

Although viscosity is known to be important in processing and handling finely ground urea, its effect has never been fully quantified. This report describes the methods used and the results obtained in the initial phases of a broad investigation of the influence of viscosity of water suspensions of minerals in flotation, thickening, filtering, and other mineral-dressing unit operations. Several types of vis-cosimeters were tested before reliable and reproducible results could be obtained on mineral suspensions. After the viscosimeter used in the research was calibrated and standardized, tests were made on six pure minerals to study the relationship of pulp density, particle size, crystallinity, and cleavage on viscosity. An orifice-type viscosimeter equipped with a mechanical stirrer gave as good results as other types and was more flexible, faster, and simpler to operate. The orifice-type viscosimeter, when calibrated and standardized with glycerin and water mixtures, proved satisfactory over a wide range of viscosities. The accuracy and reproducibility were reasonably constant between 1 centipoise and 200 centipoises, the anticipated range in common mineral-dressing unit operations.

Jan 1, 1957

Real economic growth for the year will most likely exceed the Administration's estimate of 3.2%, up from 2.9% in 1986, unless consumers change their spending patterns more than expected as a result of the October stock market decline. The economy grew at a real annual rate of 3.7% in the first three quarters of the year, Analysts agree that the stock market decline will slow economic growth-- most have lowered their growth expectations for 1988 by about 1%; but few would argue that the economy will slow significantly in the fourth quarter of 1987. [ ] During this economic recovery, personal consumption expenditures provided the main impetus for growth and a deeping trade deficit, the main hindrance to growth. In 1987, however, personal consumption expenditures grew at a lower rate than the overall economy. Mush of the economic growth resulted from a reduced trade deficit and growing investment by business in equipment to improve productivity and to meet the domestic and foreign demand for products. The declining value of the dollar resulted in a better competitive position for U.S. goods but also contributed to a rising rate of inflation as imports rose in price. Inflation, as measured by the fixed-weighted index for gross national product, was still far below the rates in the early 1980k, however. More than 2 million jobs were created during the year, predominantly in the service sectors of the economy, and the monthly unemployment rate in September fell to the lowest level in a decade. Then, after 13 months of decline, the unemployment rate edged up 0.1 percentage point to 5.9% in October.

Jan 1, 1987

By Sarkis G. Ampian

Published optical microscopic and X- ray diffraction characteristics of the following compounds are critically evaluated and compared with Bureau of Mines data : Tricalcium aluminate , calcium monoa luminate , dodecacalcium heptaluminate , dicalcium silicate , tricalcium silicate , and sodium aluminate . A recommended set of definitive optical and X- ray diffraction characteristics is presented . These values are used to identify products of the lime soda sinter process for production of alumina . Polymorphism of gamma- , beta- , and alpha prime - dicalcium silicate is reexamined , and new data are presented on polymorphism of tricalcium silicate and sodium aluminate by high- temperature X- ray diffractometry . Polymorphism is not observed for tricalcium aluminate , calcium monoaluminate , and dodecacalcium heptaluminate . Bureau of Mines data indicating a stoichiometry of 12Ca0.7A10 for the phase 5Ca0.3A1 0₂ are discussed . A critical review of the literature concerning calcium dia luminate and sodium undecaluminate ( 8 -A10 ) is also included .

Jan 1, 1964

The papers contained herein summarize results of various recent Bureau of Mines investigations in the area of mine power distribution systems. They are based on information from Bureau personnel, contractors and grantees, and Mining Enforcement and Safety Administration. Conclusions drawn from a series of parameter measurements on mine power systems, taken over a 3-year span, are presented. Personnel and equipment hazards due to faults on isolated, solidly grounded, and resistance grounded three-phase systems are discussed. Two papers cover dc applications of circuit breakers, including a novel protection scheme for trolley lines. The methods of suppressing induced arcing currents and voltages in a-c machines are evaluated. An evaluation program for ground monitors is described. Acceptance test procedures and the importance of various paparameters for trailing cable splice are covered. A number of techniques for locating faults in trailing cables are described.

Jan 1, 1975

By Eugene H. Skinner

The 7-mile Flathead Tunnel, located in the central Salish Mountains of northwestern Montana, was constructed between 1966 and 1969, With the contract awarded April 19, 1966, drill and blast tunnel excavation began September 30, 1966, and was completed June 21, 1968, in 488 tunnel-driving days, Peak advance was 66 feet per day. On June 27, 1969, all tunnel concrete lining was completed. Average wall and arch concrete placing rates exceeded 1,700 cubic yards daily, with nearly half of the concrete placed during a severe winter season. Major cost savings in concrete tunnel lining were achieved through a value engineering clause in the contract. Achieving consistent results and high rates of placement in concrete lining ranked equal to ground control in overall tunnel problems. Ground control problems exceeded expectations and were of continual concern throughout excavation, One support collapse in the tunnel and one portal slide condition developed during construction. Critical surface geologic exposures were largely obscured; only a portion could be accurately projected underground, An instrumentation program to gather basic data on rock defamation near the heading face for support purposes was a pioneering effort. The Flathead Tunnel was placed in service on November 7, 1970.

Jan 1, 1974

A working understanding of present coal mine communications equipment and its usage is an essential prerequisite to the determination of future communications systems needs. As a means of gaining this understanding, a field survey program was planned and implemented. The plan formulated called for obtaining both qualitative and quantitative data from three main areas of interest: the types, physical condition, and performance characteristics of equipment presently used in the sample of mines to be visited; the relationship present communications has to safety and productivity; and the practical, future communications needs as derived through interviews with present mine management. In compliance with the original plan, the type and physical condition of equipment in use was found through at-mine interviews of personnel responsible for installation and maintenance. Further evaluation was made through the review of equipment instruction books and maintenance manuals and through in-mine inspection of communications equipment and signal distribution networks. The performance characteristics were determined through listening to conversations and noise levels and by talk-testing from randomly selected stations throughout each mine. System operation was evaluated by asking communication system users their opinions and by noting any difficulties personnel had using the systems.

Jan 1, 1974

By R. Hogg

"The basic population balance models for agglomeration processes are reviewed and procedures are described for extending their applicability to systems with size-dependent rate constants and to the formation and growth of porous agglomerates from rigid, solid-particles. Simplified procedures for the further extension of the models to include simultaneous agglomerate growth and breakage are also described.INTRODUCTION The association of small particles into clusters or agglomerates is a significant factor in many facets of particle processing. Agglomeration processes are widely used to facilitate handling, storage and utilization of fine powders. Processes such as coagulation or flocculation are used to aid solid-fluid separation in dispersed particulate systems. Agglomeration also occurs as an accompaniment, often unwanted, to other particulate processing operations such as fine grinding, mixing and blending, transport and flow.Reliable agglomeration models are needed for improved understanding of the processes in general and of the complex role of numerous, interacting variables as well as for direct application to the design and control of industrial processes such as flocculation, granulation and pelletization. Ideally, the models should account for the primary forces responsible for agglomerate formation and growth, the effects of external forces on process dynamics, the development of agglomerate structure and its role in the process itself, and the effects of concurrent processes such as structure modification (e.g. compaction) and agglomerate breakage or degradation."

Jan 1, 1989

By George Quackenbos

The principal objective of this Program is the design, fabrication and testing of an Environmental System for operation in underground mines, to assess the effect of various mining systems on the contaminant levels near the mine face and within return airways. In order to determine the effect on airborne contamination in mines resulting from the development of new mining techniques, equipment and control systems, a Comprehensive Monitoring System is required to assess such contamination levels at critical and strategic locations and relate this information with ventilation parameters. The three variables to be sensed on a continuous basis are airborne dust concentration, methane concentration and ventilation air velocity. Each Monitoring Station will consist of a self-contained unit containing a power source and sensors to monitor the three above mentioned parameters. Ruggedness, reliability, ease 'of operation and intrinsic safety are important design objectives. Data gathered by each Monitoring Station will be fed to a Central Data Acquisition System by means of a portable transfer unit.

Jan 1, 1982

By M. R. Yenchek

The U.S. Bureau of Mines designed and constructed sensitive and coordination-free ground-fault relays (GFR's) for use on mine power systems. First, a list of GFR attributes for mine ac utilization applications was compiled. These practical guidelines specified design, construction, transient immunity, reliability, and operating criteria. The time-current characteristics of the ac and dc units, subsequently fabricated, were designed to be below the human electrocution threshold. The significant and highly variable capacitance of high-voltage distribution cables was found to preclude the sensing of ground currents in the milliampere range. However, the coordination-free system developed for high-voltage distribution should enhance safety by significantly decreasing response time to ground faults. Implementation of the sensitive GFR technology in the mining industry has the potential to eliminate the majority of injuries and nearly all the deaths resulting from contact with energized components.

Jan 1, 1990

When the Organic Act of 1910 established the Bureau of Mines within the Department of the Interior, the Bureau's programs involved only health and safety research and education, and fuels testing. As the Federal Government's primary agency for research in minerals, the Bureau has expanded its scientific and technological investigations to mining, processing minerals substances, eliminating occupational health and safety hazards in the mineral industries, economic development, and resource conservation. Today, Bureau activities cover a broad spectrum of programs for meeting the diverse (and sometimes conflicting) needs of mineral industries, government, and the public. In the 1960's, the Bureau initiated programs to resolve environmental problems associated with past mining and mineral processing. In the 1970's, the energy crisis raised the national consciousness concerning our limited supplies of domestic mineral and fuel resources. Dependence on foreign sources of raw materials critical to our national economy and competition from other countries for these world supplies stimulated the need to conserve and use with intelligence the Nation's minerals, metals, and fuels.

Jan 1, 1976

By Charles F. Jackson

Gold mining is a subject that not only appeals to the popular imagination but has vital importance to the world's economic structure. However, a discussion of the use of gold as a medium of exchange, and a basis for credit between nations and for monetary systems is not within the scope of this paper. The importance of gold in carrying on the commerce of the world, the present supply and rate of production, the probable trend of future production, the probable future requirements, and related subjects have recently received much attention from bankers and economists, and many articles on these subjects have been published. During slack periods of base-metal production due to falling prices, accompanied by scaling down of base-metal mining operations and often by the closing down of at least some mines, there usually result revival of interest in gold mining, search for previously undiscovered deposits, and reopening of some old gold mines.

Jan 1, 1932

By VAN. H. MANNING

Probably no year in the history of the United States showed greater progress in the mineral industries than 1916. Although this progress was undoubtedly stimulated by the war in Europe, which caused extremely high prices for some of the metals, yet the fact remains that mining is being regarded more as a business and less as a speculation, and the benefits of business methods are becoming evident. Practices that were almost universal a few years ago have been largely abolished, the mining public has been brought to recognize the folly of wasteful and dangerous methods, and there is a gratifying unanimity of opinion in regard to the conservation of life and health, as well as of our mineral resources. The people of the United States realize more fully than ever before the extent and value of the country's mineral resources and the possibilities that await intelligent and well-directed efforts at utilization. In the past, economic reasons caused deposits of valuable metals and industrial materials to lie idle; commercial reasons, many of them not truly economic, led to the waste of valuable constituents in many ores; the recovery of minerals from the ground was too often incomplete and accompanied by uncalculated loss; and the treatment of ores in mills and smelters saved altogether too Iowa proportion of the metals sought. Now better methods are being tried on every hand, and the unparalleled record of the year is largely due to the success of these efforts. According to the preliminary estimates of the United States Geological Survey the output of metals and minerals in this country in the calendar year 1916 had a total gross value of slightly more than $3,000,000,000. For many metals and minerals the figures broke all previous records, the new records of some products, as compared with 1915 figures, being as follows:

Jan 1, 1917

By K. K. Kelley

The first bulletin (269) 3 in this series, which appeared in 1932, compiled the entropy values then available for the elements and in-organic compounds, results being listed for some 150 substances. Elaborations and revisions followed in 1936 (272) and 1941 (280), when over 500 usable entropy values were tabulated. The present bulletin constitutes a further elaboration and revision. The accumulation of data since 1940 has been marked, and 800 entropy values now are available. The present bulletin also contains all the pertinent explanatory matter that appeared in its predecessors. Thus, it retains the same dual purpose of assembling the available values of the entropies at 298.16° K. of the elements and inorganic compounds and giving enough explanation of methods of calculating entropies to make the results comprehensible.

Jan 1, 1950

By C. A. Frenzel

Extensive spectroscopic data are needed in making reliable vibrational assignments for use in calculating thermodynamic functions of polyatomic molecules. The fundamental vibrations of organic molecules may be observed at any wavelength from 2.5 to 200 microns (micron = µ = 10-4 centimeters), but most often in the region from 3µ to 50µ. Raman spectra generally cover the range in which fundamental vibrations occur, but equally important infrared spectra usually are not measured at wavelengths longer than 25µ. This limitation results because most infrared spectra are determined for analytical purposes, which seldom require information outside the region 2µ to 25µ. Measurements of infrared spectra in the range 15µ to 35µ recently were begun by the Bureau of Mines to obtain data needed in making vibrational assignments. This report presents the spectra of the following thirteen compounds: Tetrahydrofuran, 1-methylpyrrole, piperidine, 2-methylpyridine, 3-miuthylpyridine, 2-propanethiol, cyclopentanethiol, 2-methyl-2-butanethiol, 3,3-dimethyl-2-thiabutane, cyclohexanethiol, cyclopentyl-l-thiaethane, 2,4-dimethyl-3-thiapentane, and hexamethyldisiloxane.

Jan 1, 1960

By Robert M. Becker

This investigation (in five parts) extends the theory of sample reliability from a sample consisting of a fixed number of items to a sample consisting of a fixed amount of items. Examples of a fixed amount of items per sample are samples consisting of a fixed weight or a fixed volume of unequal size particles. The extension of the theory is confirmed by experimental laboratory sampling using standard procedures. The probability distribution functions (the binomial, hypergeometric, multinomial, generalized hypergeometric, and those here called the compound binomial and compound multimomial functions) are developed from fundamentals. Their distributions are generalized to include some measured characteristic of the items. Infinite population moments are derived from moment-generating functions, and finite population moments are developed from corresponding infinite population moments using a newly defined mathematical operation. The first three experimental moments in laboratory sampling to given weights of particles are compared with the theoretical moments of their corresponding compound mult.inomial distributions. The agreement is striking. The study is divided into five parts. Part 1 deals with probability or random sampling to n items and with all sampling to n items per sample from some one probability distribution. This is the area of sampling covered by well-known theory. Accordingly, the procedures may be different but many of the results are well known.

Dec 1, 1964

By R. Hogg

"The basic population balance models for agglomeration processes are reviewed and procedures are described for extending their applicability to systems with size-dependent rate constants and to the formation and growth of porous agglomerates from rigid, solid particles. Simplified procedures for the further extension of the models to include simultaneous agglomerate growth and breakage arc also described. IntroductionThe association of small particles into clusters or agglomerates is a significant factor in many facets of particle processing. Agglomeration processes are widely used to facilitate handling, storage and utilization of fine powders. Processes such as coagulation or flocculation are used to aid solid-fluid separation in dispersed particulate systems. Agglomeration also occurs as an accompaniment, often unwanted, to other particulate processing operations such as fine grinding, mixing and blending, transport and flow.Reliable agglomeration models are needed for improved understanding of the processes in general and of the complex role of numerous, interacting variables as well as for direct application to the design and control of industrial processes such as flocculation, granulation and pelletization. Ideally, the models should account for the primary forces responsible for agglomerate ·formation and growth, the effects of external forces on process dynamics, the development of agglomerate structure and its role in the process itself, and the effects of concurrent processes such as structure modification (e.g. compaction) and agglomerate breakage or degradation.In its most general form, the process of agglomeration involves taking discrete, independent particles, bringing them into contact with one another, promoting (or allowing) interparticle adhesion to occur and then causing structure rearrangement, usually under the action of external forces. The relative importance of these steps varies with the nature of the particulate system being agglomerated and with the kinds of agglomerates being produced. Coagulation or flocculation of particles dispersed in fluids is generally dominated by the contact and adhesion steps. In the granulation of powders, on the other hand, particles are already in contact so that structure rearrangement is the principal step."

Mar 1, 1992

By R. Barany

This paper reports determinations of heats of formation (from the oxides and elements) of crystalline cadmium metasilicate and crystalline lead meta-silicate by hydrofluoric acid solution calorimetry. The results, in conjunction with known entropy values, yield free energies of formation. There are no earlier data of this type for cadmium metasilicate. The results of this investigation for lead metasilicate deviate from the literature values (which are less reliable) in the direction of increased thermodynamic stability. Both cadmium and lead metasilicate are much less thermodynamically stable with respect to their constituent oxides than are the corresponding compounds of the alkaline earth metals.

Jan 1, 1959