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By M. O. Serbousek

To further investigate the potential of precast concrete sets as a support medium for underground mines, the Bureau of Mines designed an eight-piece precast reinforced concrete drift set for a small opening. Twenty-two sets of three different member sizes were tested to destruction under two loading conditions. A discussion of the test results and typical failure patterns is presented.

Jan 1, 1969

By Fun-Den Wang

Rock bolting has become a major method of coal mine roof support because of its effectiveness, economy, and convenience. The polymeric-resin-bonded bolt has generally proved to be more effective than the mechanically anchored bolt, but the higher cost of the resin bolt limits it to applications where the increased support is essential. The low-cost high-early-strength cement grout developed during this project will encourage more widespread use of fully grouted roof bolts provided practical installation techniques can be developed. Laboratory tests of four types were performed on various rapid-set and accelerated cement products to find a material with properties suitable for replacing resins. A proprietary gypsum cement was ultimately used with good success. A field test of the cement grout was made in an operating coal mine. An intersection was bolted in the standard pattern with cement-grouted bolts and instrumented. A nearby resin-grouted intersection was also instrumented and observations were carried out in both intersections for 2 months. No substantial difference was found between the support provided by the cement and the resin.

Jan 1, 1976

By I. D. Schleicher, L. H. Rorden, F. B. Curry, T. C. Moore

The purpose of this program is to extend electromagnetic (EM) techniques for use in locating miners trapped in mines as deep as 1000 m. A previously developed EM system is considered adequate for use at mines less than 300 m deep where it has a probability of detection of 54%. A system for deep mines must keep underground equipment simple, and use extremely low frequencies (ELF), sensitive receivers, and noise cancellation. The proposed location method, developed by Develco for other applications, is based on vector field measurements from two or more static sensors and computation of source location by iterative techniques. During Phase II, very sensitive search coil sensors were built and used in a separate test to verify the feasibility of atmospheric noise cancellation. A "Breadboard" location system version without cancellation, which is a fieldable test bed to evaluate receiving and location functions, was tested and supplied. Very good results were achieved from the first in-mine test with the transmitter at a depth of 380 m. It is expected the results of this work, and additional evaluation tests in the future, will be used to define the requirements for a prototype operational system.

By Michael Schmitz, Eugene Ahrenholtz, William A. Heitbrink, Jeanne A. Zimmer, Andrew B. Cecala, Ernest S. Moyer, Earle H. Andrews, Chris C. Coppock, John A. Organiscak

Many different types of surface mining equipment use enclosed cabs to protect equipment operators from health and safety hazards. The overburden removal and mining process can be extremely dusty and can cause excessive dust exposure. To study this issue, a cooperative research effort was established between the National Institute for Occupational Safety and Health, U.S. Silica Co., Clean Air Filter Co., and Red Dot Corp. in an effort to lower respirable dust levels in an enclosed cab on an older surface drill at a silica sand operation. Throughout this research effort, a number of modifications were incorporated into the drill's filtration and pressurization system, as well as in other areas, to improve its design and performance. An average cab efficiency of 93.4% was determined with gravimetric sampling instruments when comparing the outside with the inside cab dust levels on the final design. Although this study considered just one operation, the goal was to identify cost-effective improvements that could be implemented on all types of enclosed cabs to lower respirable dust concentrations. Two critical components for an effective enclosed cab system are having a properly designed, installed, and maintained filtration and pressurization system, along with a method for maintaining structural cab integrity, which allows the cab to be positively pressurized. Another important component is maintaining cab cleanliness. Although this research was originally directed toward the mining industry, it is also applicable to agricultural or construction equipment.

By M. D. Balen

The U. S. Bureau of Mines has undertaken the development of mineral industry cost escalation factors to enable the estimation of mineral development and extraction costs for mineralized sites in Alaska throught the use of the Bureau's Cost Estimating System v2.0 (CES 2.0). For the purposes of this document, all calculations are based on, and reflect the economic environment in Alaska in July 1992. The greater cost of mining in Alaska as compared to the contiguous-48 States can be estimated for Alaskan mining operations through (1 ) the analysis of capital and operating costs for analogous mine and mill plants in operation in the contiguous-48 States; (2) the hypothetical relocation of mine and mill plants from their actual location(s) to Alaska by making engineering modifications to the mine and mill plant design as required by the Alaskan site characteristics; (3) calculation of the cost of the required engineering modifications and; (4) the escalation of all costs to a level representative of the economic environment in Alaska at some specific point in time.

Jan 1, 2011

By Frank A. Peters

This evaluation of the sulfurous acid process for the production of metallurgical-grade alumina is the first of a series concerning various known methods of extracting alumina from low-grade aluminous materials and was undertaken to permit comparison with other processes. In the process with which this Bureau of Mines report is concerned, calcined clay is leached under pressure with 20 percent sulfurous acid and then filtered to remove a siliceous residue. The aluminum sulfite remaining in the filtrate is precipitated as a monobasic sulfite which, together with iron sulfite, is then decomposed under pressure to form a crude alumina hydrate and iron oxide. This intermediate product is purified in a modified Bayer process to yield alumina suitable for electrolytic reduction to aluminum. A study estimate (16)3 is used for these evaluations. The capital cost, not including land, is estimated at $95,701,600 on a Marshall and Stevens index basis of 240.0 for a plant producing 1,000 tons a day of alumina or 350,000 tons a year. The annual operating cost for this size plant is estimated at $22,831,100 or $65.23 per ton of alumina using clay at $1 per ton. Depreciation and local taxes are included in the estimate, but profit and Federal taxes are not considered.

Jan 1, 1962

By Robert L. Lagace

This final report documents the work done by Arthur D. Little, Inc. (ADL) on behalf of the U.S. Bureau of Mines, Pittsburgh Mining and Safety Research Center (PMSRC), on Contract R0122026 (which began in August of 1971). Under this contract ADI provided technical assistance to the Bureau on a task basis on virtually all aspects of the Bureau's programs related to present and planned emergency and operational communications and miner location systems for underground coal mines. The work consisted of independent investigations, analyses, experiments, breadboard and prototype hardware development, workshops and technology transfer seminars on mine communications, and on-going evaluations and guidance related to the Bureau's contracted programs on electromagnetic noise, mine communications systems, and trapped miner location. This final report documents the work in two volumes, Volume I, "Emergency and Operational Mine Communications," and Volume II, "Seismic Detection and Location of Isolated Miners." The Tables of Contents of both Volumes are included in each Volume. Phase I of the contract was devoted to performing an in-depth assessment of electromagnetic noise measurements taken by several contractors and other investigators, and then defining a new noise measurement program and instrumentation system tailored to obtain the necessary but missing noise data. These data are required for use in the design of new emergency and operational communication systems. This work, and the follow-on coordination and guidance activities of ADL on this noise measurement program in subsequent phases of the contract, are treated in Part One of Volume I.

Jan 1, 1974

By Robert P. Bruno

This report covers the study of the feasibility of using a hand-held infrared viewer as a methane indicator to observe methane gas at the face of an underground coal mine. The objective of this program was the development of a hand-held device to remotely detect the presence of concentrations of methane gas in underground coal mines. Convenient "mapping" of methane from a remote location would allow rapid and safe corrective procedures for working personnel. Modified commercially available equipment was evaluated both in the laboratory and in a working mine. Although readings were obtained and the general principle of operation demonstrated, the power levels necessary, and protective enclosures required, would raise the weight of the instrument beyond practical limits of portability. Based on currently available technology, it is the conclusion of the investigations that a practical, portable, hand-held visual methane indicator is beyond the state-of-the-art. The recommendation was, therefore, made that work be suspended, and the results and data compiled and presented in a final program report.

Jan 1, 1979

By Dennis E. Jensen

Field studies were performed during blasting operations for strip coal mining above the room and pillar workings at Jenny mine in eastern Kentucky. The study is part of the Bureau of Mines program to develop criteria for the proximity of surface blasting to underground mines. Measurements and observations were made to identify physical changes in the mine. No change in the frequency of roof falls or any other indication of apparent damage was noted. Recordings of blast induced vibrations were made using sensors on the roof and floor of the underground mine and at the ground surface. A maximum particle velocity of 17.5 in/sec was recorded on the mine roof. The vibration data were analyzed and comparisons were made between roof vibration levels and those recorded on the mine floor and at the ground surface. Results are compared with previous blast vibration studies. Recommendations are made for further study toward developing criteria.

Jan 1, 1979

By C. Özgen Karacan

Gob gas ventholes (GGV) are used to control methane inflows into a longwall operation by capturing it within the overlying fractured strata before it enters the work environment. Thus, it is important to understand the effects of various factors, such as drilling parameters, location of borehole, applied vacuum by exhausters and mining/panel parameters in order to be able to evaluate the performance of GGVs and to predict their effectiveness in controlling methane emissions. However, a practical model for this purpose currently does not exist. In this paper, we analyzed the total gas flow rates and methane percentages from 10 GGVs located on three adjacent panels operated in Pittsburgh coalbed in Southwestern Pennsylvania section of Northern Appalachian basin. The ventholes were drilled from different surface elevations and were located at varying distances from the start-up ends of the panels and from the tailgate entries. Exhauster pressures, casing diameters, location of longwall face and mining rates and production data were also recorded. These data were incorporated into a multilayer-perceptron (MLP) type artificial neural network (ANN) to model venthole production. The results showed that the two-hidden layer model predicted total production and the methane content of the GGVs with more than 90% accuracy. The ANN model was further used to conduct sensitivity analyses about the mean of the input variables to determine the effect of each input variable on the predicted production performance of GGVs.

Jan 1, 2009

By W. C. Blanchard

Time Domain Reflectometry (TDR) is a remote sensing technique using active backscatter. This technique is applicable to the testing for faults and multiple partial faults on cable. The battery operated hardware developed on this con¬tract has tailored this technique for testing of mining equipment trailing electrical cables. The processing of-t-he back-scatter is accomplished using a microprocessor. The visual output from the hardware to the operator is; the type, magnitude and distance to the cable fault in a numerical format. This greatly simplifys the use of this techniques for the operator.

Jan 1, 1980

By Choon Kooi Quan

Water availability is essential for mining and minerals processing. To provide government and industry with recent data for water use planning and management, the Bureau of Mines canvassed a number of U.S. producers of nonfuel minerals to determine their water use in 1984. Data were analyzed and compared with previously published data in order to examine historical trends in water utilization in the nonfuel minerals industry and to estimate water requirements in the year 2000. Total water use in the domestic nonfuel minerals industry during 1984 was estimated at 2,267 billion gal, of which 571 billion gal was new water and 1,696 billion gal recirculated water. The largest users of water were the phosphate rock, iron ore, copper, sand and gravel, and crushed stone industries, together accounting for almost 90% of total used. More than one-half of all water was used in Florida, Michigan, and Minnesota. In the year 2000, total water use will amount to an estimated 2,679 billion gal, of which 810 billion gal will be new water and 1,869 billion gal recirculated water. Most of this water would be used in producing the foregoing suite of minerals,

Jan 1, 1988

By C. B. Kenahan

The Bureau of Mines is developing methods for reclaiming the metal and mineral values contained in municipal incinerator residues. This report describes the first phase of the research, in which reliable methods for sampling and analyzing municipal residues were established and the composition and characteristics of the residues were determined. Samples were obtained from a variety of grate-type furnaces and also from a rotary kiln furnace. The samples were processed on a batch basis and separated into their natural categories by a variety of methods including screening, magnetic separation, air separation techniques, and handpicking. The main components of the residues were determined to be metal and metal oxides, glass, and ash.

Jan 1, 1968

By G. Ahnell

Throughout portions of four (4) heavily mined Appalachian states subdivided by the Mine Safety and Health Administration (MSHA) as: District 3 -Northern West Virginia and Maryland; District'" -Southern West Virginia; District 5 -Virginia; and District 6 -Eastern Kentucky, active coal mine waste embankments associated with mechanical and/or chemical coal processing facilities of various levels of coal preparation were inventoried. For each site plant specifications, disposal techniques, embankments' characteristics, and coal source data were accumulated. Mapping at 1: 24, 000 and 1: 250,000 scale and Disposal Site Characterization forms were developed to present the findings. Associated abandoned surface and underground openings near each site were also indicated as well as locational data for each site and the areas environmental conditions - temperature, precipitation and vegetation types. A state-of-the-art review of coal preparation, waste disposal, and alternative uses of coal waste is also included.

Jan 1, 1982

By C. A. Hesse

The Quartz Hill Molybdenum Project, In Southeast Alaska, was the first mining project to attempt the permitting of a submarine tailings disposal system in the United States, since the passage of the National Environmental Policy Act of 1969 and the Clean Water Act of 1977. Over $20 million was spent by the project developer in baseline data gathering and In funding the preparation of the four Environmental Impact Statements and other environmental documents required at various stages of the project between 1977 and 1988. Because of the timing and a unique set of environmental, legal and regulatory requirements which applied to this project, innovative approaches were developed. This report describes those requirements and the developments, and gives a full historical account of the campaign for permitting submarine tailings disposal at Quartz Hill, until denial of the NPDES permit application by EPA in September 1 990. The extensive studies done for Quartz Hill suggested that under certain conditions the selection of submarine tailings disposal can be the overall environmentally preferred alternative for a mining project. The Quartz Hill story illustrates the complexity of the existing permitting structure and paints out the desirability of rationalization to achieve a more effective system.

Jan 1, 1993

By James P. Rider, Charles D. Taylor, Edward D. Thimons

Research was conducted to investigate how ventilation of a mining face is affected when scrubber flow is greater or less than intake flow. Tests were conducted in a full-scale surface test gallery built to simulate a mining entry with a continuous mining ma- chine at the face. Methane gas was released at constant flow at the mining face. Gas measurements taken at six locations near the face were used to evaluate how well the face was being ventilated. Increasing scrubber flow resulted in lower methane levels even when scrubber flow was much greater than intake flow.

This chapter summarizes data on crude mineral production for the United States, its island possessions, and the Common- wealth of Puerto Rico. Included also are tables that show the principal mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables 'were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is normally termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the production of auxiliary processing at or near the mines.

Jan 1, 1978

By Sean Gallagher

The human body is remarkably adaptable and capable of performance in a wide variety of environments and circumstances. It cannot be said, however, that the body is capable of performing equally well under all conditions. In fact, when faced with certain types of tasks or environmental demands, the body may have to adapt using methods that result in substantial performance limitations. Such a phenomenon is evident when workers must adopt unusual or restricted postures during performance of physically demanding work tasks. For the purposes of this discussion, the term "unusual posture" will be considered as any working posture other than typical standing or sitting positions. The term "restricted posture" designates postures that are forced upon workers due to restrictions in workspace. The vast majority of ergonomics research has focused on establishing design criteria for work involving standing (e.g., Snook and Ciriello, 1991; Waters et al., 1993) or seated postures (e.g., Grandjean, 1988), and understandably so. However, it must be recognized that there are numerous jobs (e.g., underground miners, aircraft baggage handlers, plumbers, agricultural workers, mechanics, etc.) where workers must perform in less desirable postures such as kneeling, stooping, squatting, and lying down (Haselgrave et al., 1997). Unfortunately, experience has shown that many ergonomics techniques used to analyze or design standing or sitting workstations often do not adapt well to situations where a restricted

By F. W. Wood

The use of consumable.-electrode arc melting as a production technology is growing. One advantageous feature of this process is that it avoids ingot contamination by soluble crucible materials by employing a chilled metal crucible. Because the thermal balance under these conditions is rather delicate and does not necessarily provide a favorable environment for solidification, catastrophic imbalances can occur. The effectiveness and mechanistic roles of various factors are mostly unknown, and more intelligent insight regarding the distribution of temperature and heat is needed. Experience has provided several pertinent observations, some of which are quite superficial. The most meaningful data have resulted from studies of molten pool shapes and sizes and from measurements of heat flow through crucible walls. Overall experience, intuitively interpreted and supplemented, is sufficient nevertheless as a basis for a boundary-value treatment of the problem. A mathematical analysis based on a separation of variables, using conventional differential equation methods, provides a useful solution. For a cylindrical ingot, the temperature varies as a Bessel function of an argument proportional to the radius and as an exponential function of longitudinal position. Trial calculations using the problem solution seem to verify the general correctness of the result as compared with experience. The role and nature of solution parameters are also clarified, though not entirely resolved. It is revealed that the barrier to heat flow at the ingot-crucible surface has a prominent influence. Utility of the model embodied in the problem solution is readily demonstrated by considering a variety of contemporary questions about arc melting, and it is hoped that utility can be enhanced by improvement of the model.

Jan 1, 1968

By Thomas J. Peters

A mineral survey of the Sill Hill RARE II area (No. 5304), covering 5,200 acres (2,100 ha) of the Cleveland National Forest, San Diego County, California, was conducted by the U.S. Bureau of Mines and the U.S. Geological Survey. This survey was in conformance with the Resource Planning Act (RPA) of 1974, as amended by the National Forest Management Act of 1976, to provide mineral resource information for study area classification. Bureau of Mines personnel made an economic appraisal of mineral deposits by searching pertinent geological and mining publications as well as U.S. Bureau of Land Management, U.S. Forest Service, and U.S. Bureau of Mines files and records. Known mines, prospects, and mineralized localities were examined during 1981, and sampling and mapping were done where warranted. The Geological Survey 'did geologic mapping, geochemical sampling, and geophysical surveys to aid this study.

Jan 1, 1983