Search Documents

By Charles D. Martens

Raw non fuel minerals produced in the United States during 1981 had an estimated value of $25 billion, about the same as that of 1980. In terms of 1980 dollars. the value of minerals produced during 1981 was $23 billion.2 This chapter includes tables for 1980 that were not available for publication in the 1980 Minerals Yearbook, but does not include the corresponding tables for 1981. The underlying causes of the overall decline in U.S. nonfuel mine production during 1981 were varied, but the common factor was the worldwide recession. In some cases the decline was traced to foreign competition. For example, iron ore production was lower in part because of increased imports of steel products such as coiled steel sheet. Another problem experienced by the domestic mining industry was the continuing difficulty in attracting capital. This was due in part to the attractiveness of investments outside the mining industry, such as short-term, high-interest securities. Another reason was the importation of commodities from countries where overall costs were lower because of such factors as high ore grade, lower taxes, lower wages, government subsidies, and less stringent safety and environmental regulations.

Jan 1, 1982

Develop a means for analyzing seismic crosshole data to predict and monitor the Flow of leach solution during in situ mining. Background Improvements in predicting and monitoring in situ leach solution flow would aid in planning well field configurations. These improvements would also facilitate permit application by assuring regulatory agencies that leach solution would not escape from a well field undetected. Seismic tomography can detect fractured zones, which enables the prediction of probable flow paths, and it is a promising technique for monitoring leach solution injected above the water table. Tomographic analysis of crosshole seismic data provides a two-dimensional picture of the distribution of seismic velocities between the transmitter and receiver boreholes. The positions of fractured zones and of leach solution can then be inferred from the seismic velocities.

Jan 1, 1989

By Jerry E. Olson

In 1985 the U.S. Bureau of Mines conducted a mineral survey of 68,458 acres of the Clan Alpine Mountains Wilderness Study Area (NV-030-102) which covers 196,128 acres in Churchill County, NV. Most of the area studied is underlain by Tertiary volcanic rocks. In the northeast corner of the study area, an upthrown block of Triassic sedimentary rocks partially extends into the area. The study area is probably part of a large eroded caldera. No major mines or active claims are within the study area. Field investigations included examination of workings in Starr Canyon, historical and recent mining activity near the mouth of Florence Canyon, other mining claims, and anomalous zones delineated by data from Great Basin GEM Joint Venture studies. No mineral resources were identified, but sample results indicate one significant mineralized zone situated along a northwest trend between the head of Starr Canyon and the head of Cherry Creek may contain precious metal resources. Further investigation of this zone is warranted.

Jan 1, 1987

Provide an environmentally compatible means of producing lead from galena concentrates that replaces the current high-temperature pyrometallurgical primary lead smelting process and supplies pure lead metal within present and proposed Environmental Protection Agency (FPA) and Occupational Safety and Health Administration (OSHA) lead emission standards. Approach The U.S. Bureau of Mines developed an energy efficient and pollution-free leach-electrowinning method for use in recovering pure lead metal and byproducts from lead sulfide concentrates.

Jan 1, 1989

By Stephen A. Hare, O&apos

The melting, casting, and welding of the Raney nickel alloy (42 pct Ni-58 pct A1), a methanation catalyst useful in coal gasification, were investigated. Melting was done in graphite crucibles by heating aluminum and adding nickel using a cryolite slag cover. Casting conditions were found to be optimum when the melt temperature ranged from 1,125° to 1,200° C and the mold temperature ranged from ambient to 250° C. Suitable mold materials were found to be quartz, heat-resistant glassware, olivine, and zircon. Welding of the alloy can be accomplished using tungsten inert gas process. Tensile strength of the alloy, in the as-cast condition, was found to be 2,000 1b/sq in with an impact strength of less than 1 ft-1b. The coefficient of thermal expansion was determined to be 18.4 x 10-6/° C after heat treatment.

Jan 1, 1977

Provide the mining industry with a method for determining the gas content of ore bodies and associated strata for use in mine planning, Approach Samples of various rock types are collected and tested to determine gas content in conjunction with sample size, the collection method (i.e. whether the sample was collected from a core sample or by hand) mine gas emission, and the geologic location from which the sample was taken, such as near a fault, outburst area, or other geologic anomaly. How It Works Two methods were developed by the Bureau of Mines to determine the gas contents of rock samples. The first method developed involved dissolving minerals to measure gas emission. This method, however, can only be used with soluble minerals. A second method, therefore, was developed for use with insoluble minerals. With this method, the sample is crushed in a ball mill. Although the dissolution method is faster and more accurate to use, the crushing method is also advantageous because its use can more closely approximate a mining situation; the sample is crushed as in mining and the amount of gas released relates to the amount of gas that would be released during a mining operation. The dissolution method is applied to soluble minerals, such as rock, salt, or trona, in a sealed chamber. Gases released during dissolution are collected for analysis by gas chromatography. One advantage in using the dissolution method is that the test apparatus is relatively inexpensive. In addition, test can be performed at any scale, from single crystal samples to a solution mining operation.

Jan 1, 1983

By E. P. Youngman

This paper is one of a series of digests of foreign mining legislation and court decisions that is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate-mines in various foreign countries. This interpretation of the mining laws of Greece was prepared from information furnished by Ralph B. Curren, American assistant commercial attache, Athens, in reply to a questionnaire of the United States Bureau of Mines, transmitted through the courtesy of the commercial laws division of the Bureau of Foreign and Domestic Commerce. INTRODUCTION In his report,3 Mr. Curren states that the source of his information was the Director of Mines of the Greek Ministry of National Economy and the Mining Code of Greece, which was, compiled from existing laws in 1929,4 and which has since been modified by several acts of Parliament.

Jan 1, 1932

By E. L. Rawlins

A previous report4 has explained that pipe lines for the transmission of natural gas should be buried to minimize temperature fluctuations because when excessive the latter decrease accuracy in measuring gas volume and increase leakage of gas due to expansion and contraction in the pipe joints. These effects are governed by the rapidity of the temperature fluctuations and by the total variation over a period of time. The temperature of gas flowing through a pipe line depends to a large extent, upon the temperature of the ground adjacent to the pipe; hence, fluctuation of the ground temperatures at various depths determines the economic depth at which pipe lines should be buried. Scope and Purpose of Report This report covers a record of the daily atmospheric temperature fluctuations at Bartlesville, Okla., for 12 months and a-similar concurrent record of the temperature variation 1, 2, 3, and 4 feet below the surface of the ground.

Jan 1, 1928

By Forrest T. Moyer

Injury experience in the mineral mining and processing industries during 1968 was slightly improved in the nonfatal-injury record but worse in the fatality record. The resulting frequency rate of all injuries was slightly better, whereas the injury-severity rate retrogressed appreciably from the figure for 1967. Overall operating activity, as measured by man-hours of worktime, was slightly higher in 1968. However, there were several major segments of the mineral industries in which activity was lower owing to reduced demand for mineral products and to several major work stoppages. These statistics comprise the injury and work experience of all personnel engaged in production, exploration, development, maintenance, repair, and force-account construction work, including supervisory and technical personnel, and working partners and owners at mineral-producing and mineral-processing establishments in the United States. Data concerning officeworkers are excluded except for the oil and gas industry for which such information is not separable. All injury rates and totals are calculated from data before rounding. The data for 1968 are preliminary except for the anthracite, coke, petroleum and natural gas, native asphalt, peat, and slag industries, which are final. The figures represent full coverage for all industries except oil and gas for which coverage is not complete, particularly with respect to small companies.

Jan 1, 1970

By Thomas M. Barczak

Longwall operators are again pushing the envelope in terms of life expectancy for longwall shields. State-of-the-art shields are now expected to last more than 60,000 loading cycles, twice the life expectancy compared with those of a decade ago. A review of trends in shield design shows that shields continue to increase in both size and capacity. Some state-of-the-art shields now weigh over 30 tons and provide up to 1,200 tons of support capacity. Although life expectancy has increased and modern shields are structurally more reliable, premature failures do still occur. This paper provides an engineering and operational assessment of shield design and provides key points to observe in what causes premature shield failures. Design practices to improve structural margins of safety that will prevent premature failures from occurring are also examined. A survey of recent shield failures is provided, as well as trends in shield design and how they might impact the performance and longevity of a shield. Hydraulic failures are more common than structural failures. Although hydraulic failures occur on all aging longwall shields, they often go undetected for long periods, resulting in degraded support capacity that can lead to serious ground control problems. The fundamentals of shield hydraulics are described in order to evaluate hydraulic failures that plague all shields at some point in their service life, and practical methods to detect hydraulic failures are examined. The paper concludes with recommendations for inspecting damaged shields and safety precautions regarding their continued use.

Jan 10, 2000

By Maria I. De Rosa

This report analyzes mine fires for all U.S. underground and surface metal/nonmetal mining categories during 1990–2001 by state and six successive 2-year time periods. Injury risk rates are derived, and ignition source, methods of detection and suppression, and other variables are examined. Fires involving contractors are also included in the analysis. The data were derived from Mine Safety and Health Administration (MSHA)mine fire accident publications and verbal communications with mine personnel. The analysis will provide the National Institute for Occupational Safety and Health, MSHA, and the mining industry with a better understanding of the causes and hazards associated with mine fires and an increased awareness aimed at preventing and reducing fire hazards. It will also form a basis for future fire research programs.

Jan 11, 2004

By Fred N. Kissell

Methane-flow and pressure data taken from a mine in the Pocahontas No. 3 coalbed are compared with flow rates from lump coal obtained in laboratory experiments. From this, it is concluded that the main source of gas is the intact coalbed rather than a "crushed zone" near the working face. The permeability and sorption capacity of the intact coalbed are calculated and gas emission rates are theoretically accounted for.

Jan 1, 1972

By Larry P. Jackson

As part of the current research effort in shale-oil chemistry conducted by the Federal Bureau of Mines, reduced chlorophyllins were prepared and pyrolyzed in an effort to identify the role of plant pigments and their decomposition products in the nitrogenous compounds found in the product of oil-shale pyrolysis. The properties of the chlorophyllin pyrolysates were related to the composition of the reduced chlorophyllins with particular emphasis on the amount and types of nitrogen compounds formed. A comparison based on the types of nitrogen compounds present was made betvJeen shale oil and the chlorophyll in pyrolsates. In order to make this comparison, a sample of shale-oil light distillate was separated into polar and nonpolar fractions, and a careful examination of the polar fraction was conducted to obtain an accurate picture of the types of nitrogen compounds present. The information gathered from these studies was used to evaluate reduced chlorophyllin as a model of oil-shale kerogen insofar as the production of nitrogen compounds was concerned. The results indicate that the reduced chlorophyllin does yield nitrogen products which are directly related to the nitrogenous compounds in shale oil, and it therefore represents a good model of shale-oil kerogen.

Jan 1, 1975

By J. J. Forbes

The investigation of major and minor coal-mine disasters has been a routine function of the Bureau of Mines since its inception in 1910, and the facts obtained during such investigations have been used as a basis for determining the precautions that the managements and employees of many mines are observing to forestall similar occurrences. The Bureau has conducted research on roof-control and other mine problems, but a comprehensive study of other fatal accidents was not attempted until February 10, 1950, when the policy of investigating all coal-mine fatalities in the United States was approved by Bureau of Mines Director James Boyd. The investigations are being conducted by Federal coal mine inspectors functioning under the provisions of the Coal Mine Inspection and Investigation Act of May, 1941, Public Law 49; and reports covering the investigations are distributed to management, the State mine-inspection agency, and representatives of the mine workers' organization have jurisdiction at the mine.

Jan 1, 1951

By Theodore Christos

The Bureau of Mines sponsored an investigation of the thermal oxidative degradation characteristics of certain solvents and hydraulic fluids used in underground mining operations. The following halogenated solvents were studied in view of their usefulness and their flame retardant property: tetrachloroethylene, C12C = CC12; 1, 1, 2-trichloroethane, CIH2CCHC12: and trichloroethylene, C12C = CHC1. The hydraulic fluids studied were representative of five groups approved by the Mine Safety and Health Administration for underground operation, namely: glycol-water solutions, mineral oil-water emulsions, synthetics other than phosphate esters, synthetic phosphate esters, and mixtures of phosphate esters with mineral oils and other ingredients. It was observed that the partially halogenated solvents present a greater potential toxic hazard than the fully halogenated materials, due not only to the easy production of hydrogen chloride but also to their ease of oxidation leading to the formation of phosgene and carbon monoxide. The pure phosphate esters exhibited the best thermal oxidative stability of the five groups of hydraulic fluids tested. A fluid containing phosphate esters mixed with mineral oils and other unidentified ingredients appeared to be the most hazardous On the basis that it produced very toxic acrolein and phosphine.

Jan 1, 1980

By I. L. Nichols

Laboratory characterization studies have investigated the processing variability of carbonaceous uranium-bearing materials found in-sandstone deposits. This work was conducted by the Federal Bureau of Mines in support of its goal to maintain an adequate supply of minerals to meet national economic and strategic needs. Conventional processing produces only partial uranium recovery from these ore materials. Ore samples from New Mexico, Texas, and Wyoming were examined, and each responded differently. Using direct acid leaching techniques, some of the ores required acid additions of only 50 pounds per ton, while others required 300 pounds per ton of material. Maximum extractions ranged from 83 to 94 percent in the six ores tested. Roasting those ores prior to leaching improved extraction of the uranium to the 90 to 99 percent range. An oxidative autoclave treatment used with five of these ores resulted in extraction of 78 to 97 percent of the uranium. The experimental studies also showed that some carbonaceous materials can be concentrated by froth flotation. The flotation tailings were amenable to acid leaching, and up to 98 percent of the uranium was extracted from this type of material.

Jan 1, 1979

By Doris M. Hyde

The economy of Belize continued to be relatively unaffected by activity in the minerals sector. Mining production consisted of limestone, marl, and sand and gravel. All production was used for domestic construction projects. By the end of 1979 the major oil companies had, temporarily at least, ceased active exploration efforts. Esso Ventures, Inc., after drilling three dry holes in southern Belize, planned to reappraise its activities. The Reef Exploration, Ltd., concession was acquired by Anschutz Oil Co. (81.25%). with minority interests held by Anglo Oil Co. and Carolina Oil Co. The Anschutz group drilled offshore in the Gulf of Honduras and in Belize Harbor. Echo Exploration has a con-cession along the Mexican border and Spar-tan Petroleum Corp. obtained seven exploration licenses covering 768,000 acres in northern Belize. Spartan's concessions included about 130,000 acres offshore, with the remainder along the southeastern rim of the Yucatan Peninsula. Placid Oil Co. took an interest in the Spartan acreage and became operator. Seismic exploration was underway in 1979. A Mexican company, Pan American Oil and Gas, S.A., was awarded two exploration concessions, one in southern Belize and one near the Mexican border.

Jan 1, 1981

By Dean H. Ambrose

A computer model was created that generates contact data by means of simulation while altering several variables associated with the machine and its operator. These variables include work environment, the operator's anthropometry, work posture, choice of risky work behavior, and the machine's appendage velocity. In the model, a contact means two or more objects intersecting or touching each other, e.g., the appendage colliding with the operator's hand, arm, head, or leg. This report documents the code development of special features of the computer model, random virtual human motions and behaviors, which made it possible for researchers to study hazardous interactions, such as contacts between the operator and machine. The original idea for random virtual human motions began with the need for a model that, when simulated, would experimentally mimic machine and human actions that could cause actual injuries or fatalities in the workplace. Injury incident investigation reports do not usually contain enough information to aid in studying this problem, and lab experiments with human subjects are also not feasible because of safety issues and ethical issues. Early investigation that evaluated the feasibility of random motions resulted in a primary programming structure and building blocks for code expansion. Basic motions and standard derivation data provided random parameters for the operator's movement in the random motion code. Experimenting with basic motions in preliminary models helped researchers devise a random motion technique that worked with xyz motion parameter values from basic motion parameters. Both values were the building blocks used in motion commands that comprised the core of the random motion code. When the code is executed in a three-dimensional computer model, it generates realistic starting positions for the operator's (virtual human) body and body parts and realistic motions mimicking a work sequence with a valid range of variation in movements. Researchers developed several rules for the random motion technique that, when applied, will maintain directional integrity of a virtual human's basic motions. From previous research, researchers formulated the algorithm that determines the behavior during machine operation. The decision algorithm was needed by the random motion code to randomly select what behavior to use for a simulation execution for a realistic representation of the operator's motions and risky behaviors during work tasks. The operator's chance of avoiding the moving appendage was also a concern to ensure that data reflecting a near-miss would not be considered a contact. Therefore, to filter a database obtained from simulations for actual contacts, it was necessary to track the operator's field of view and determine from this information when the appendage is in and out of the operator's view. NIOSH researchers successfully applied random motions and risky behaviors to examine the speed range of a roof bolter machine appendage for different workplace scenarios and compare statistically which is most likely to cause contacts (and possible injuries) to miners. Researchers in this study believe that the use of such simulations, treated with advanced statistical procedures, are extremely useful tools to evaluate the hazards of tasks where it is not possible to perform experiments with human subjects.

Jan 3, 2004

By Clarence O. Babcock

This report describes the results of Bureau of Mines laboratory and preliminary field tests on a rock bolt of helical shape. The flexible construction allows the bolt to maintain a more stable load level than is possible with a straight bolt. Bolt load changes resulting from anchor slippage, blasting shock, or changes in mine geometry with mining advance are minimized. Preliminary field tests were performed at the Kaiser Steel York Canyon mine where the load changes of straight and helical bolts were measured using a vibrating-wire load gage. The field tests were performed to establish the viability of the concept of a helical bolt. The practical usefulness in terms of performance and economics remains to be shown. The change in bolt load for the flexible bolts was one-third that for the straight bolts. There were no malfunctions of the gage, and the bolts maintained a more uniform load than the straight bolts used as controls.

Jan 1, 1978

By R. A. Keaens, L. C. IlsLey

For the purpose of this paper a junction box is defined as " a fused switch, inclosed in an explosion-proof compartment, provided with a ready means of connecting or disconnecting a trailing cable without exterior arcing." Junction boxes are intended for use 'at the end of trailing cables and are usually placed outby the last open break through in a coal mine. Where it is not safe to supply current through nips or a trolley, junction boxes suitably spaced along an entry permit tramming and movement of machines with safety, although not with any considerable speed. Junction boxes serve a threefold purpose: (1) They prevent dangerous arcing at the outby end of trailing cables; (2) they afford a safe, practical means of fusing or otherwise protecting the trailing cable; and (3) they provide an efficient means of transmitting power from the power circuit to the trailing cable. The first purpose is the most important from a safety standpoint. Dangerous arcing-that is, arcing capable of igniting gas-frequently takes place where trailing cab1c.s are attached to the power circuit. At either 250 or 500 volts only a very small arc is required to ignite mine gas. The usual method of connecting the trailing cable to the power circuit by cable nips or trolley taps does not make a good electrical connection; hence arcing may be expected at any time. Furthermore, junction boxes eliminate the personal hazard attendant upon the use of trolley taps by removing the possibility of accidental contact with trolley hooks or wire and the liability to injury due to manipulation of the device. In the general scheme of mine ventilation it is assumed that gas will not accumulate where junction boxes are placed, an assumption based on the normal operation of the ventilating system. In many

Jan 1, 1929