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By Gordon R. Sima, John L. Bennett, Roger L. King

Electric shocks are a serious problem in the mining environment. Because of extremely wide ranging use of electrically powered equipment in the mining industry, the hazard to personnel due to electrical shock and related injuries are not restricted to any single area but cover the entire spectrum of mining activity. Electrical accidents, resulting in personal injury, due to im- proper or complete lack of grounding of electrically operated mining machines, form a significant percentage of the overall electrical accident picture. The object of this paper is to describe methods of detection of unsafe electrical conditions with respect to the grounding of electrically operated mining equipment. It also includes a discussion of prototype instruments which effectively monitor the condition of the grounding safety devices currently in use on mining equipment and warn of dangerous conditions as soon as they appear. The paper is based on work accomplished under USBM Contract Number 50357115. The contract was initiated under the Pittsburgh Mining and Safety Research Center Program. It was administered under the technical direction of PM and SRC with Mr. Roger L. King as the Technical Project Officer. Mr. Daniel B. Dawkins was the Contract Administrator for the Bureau of Mines.

By H. W. Kilau

The Bureau of Mines tested chromium-bearing waste slags from industrial stainless steel and other chrome alloy operations to determine their chromium leachability characteristics under acid precipitation conditions and to devise measures to prevent any pollution originating from this source. Two critical slag composition factors were found to control the chromium leachability: (1) CaO:Si02 ratio and (2) magnesium content. Above a 2.0 CaO:Si02 ratio, chromium exists in slag as CaO·Cr203, which can be vulnerable to leaching by acid precipitation especially if oxi-dized to CaCr04 when exposed to the environment over an extended period. Maximum chromium leachability from industrial slags occurred when the composition of the slag had about a 2.0 CaO:Si02 ratio. Between a 1.0 and 2.0 CaO:Si02 ratio, in the presence of sufficient magnesium, MgO ·Cr203 was formed, which is very resistant to oxidation and to dissolution by simulated acid precipitation. Addition of magnesium silicates to molten slag to fix the chromium in the MgO·Cr203 form was successful in preventing chromium leaching in simulated acid rain solutions. Experiments showed olivine and waste taconite tailings were suitable for this purpose. Olivine addition to a waste slag having a composition vulnerable to leaching (CaO:Si02 > 2) reduced the chromium leachability more than 80 pct.

Jan 1, 1984

By Lowell B. Moon

Concern over possible wartime shortages finally resulted in passage of the Strategic Materials Act in 1939. As authorized by one section of this legislation, the Bureau of Mines proceeded to investigate deposits of seven strategic minerals with the objective of developing tonnages of low-grade material that could be mined in an emergency. During the war, the size of the program and the number of strategic minerals were increased, and the objective was the more immediate one of aiding production. Since the war, the size of the program has been reduced, but the number of minerals on the strategic list continues to be large. The objective has returned to that of 1939. In the course of the program, more than 10,000 examinations were made and about 1,300 projects were run on deposits of 33 different commodities. A considerable contribution to war production was made in six of the commodities investigated, and a minor contribution was made in twelve others. Substantial reserves have been indicated in 19 minerals. Private interest is currently active in some of the deposits developed in 14 commodities.

Jan 1, 1950

By J. E. Spurr

"Zinc Industry in BelgiumBy March F. Chase, Consulting Metallurgist, Bureau of MinesBelgium for many years was the principal spelter producing country of the world. Gradually its production was surpassed by that of Germany, and Germany in turn lost first place by the production in the 77ti.tad States. For the ten years previous to 1914, 21.6 per cent of the world's spelter was produced in Belgium. Of this production approximately 40 per cent was exported. A large percentage of the balance was rolled and of the shoots thus produced a considerable quantity was also exported.From an economic standpoint even before the war, the Belgian industry was in a unique, if not praoarious, position. Dependent upon foreign countries for ore and foreign markets for sale of products, smeltor was at a distinct disadvantage when compared with some of those of other localities. These disadvantages were partly offset by cheap coal and labor and by whatever there is of value in experience and what we may term for want of a better expression smelting tradition. However intangible this latter may be, it did have and has today an influence on commercial operations.One must not overlook the effect it will have on the revival of the industry. It may not be the determining factor but the fact that for so many years this industry flourished in Belgium, and played such an important role in the industrial life of the country will decide many operators to attempt to re-establish their operations.In 1913 the Belgian spelter plants produced 204,220 long tons of spelter or approximately 20 per cent of the world's production. During this year 500,000 to of ore were treated. The actual value of all of the products derived from treating sine ore amounted to 225 million frames."

May 1, 1919

By H. F. Yancey

The development, manufacture, and sale of small coal stokers suitable for domestic use has provided a new industry in the United States at a time when badly needed. Sales of domestic stokers have doubled each year for the past 4 rears, until in 1936 probably more than 90,000 such units were put into use. According to reports of the Bureau of the Census 79,543 residential stokers were sold in the first 10 months of 1937 by 109 manufacturers. This rapid expansion has made itself felt in the coal-mining industry. The smaller sizes of coal, either in a sized or slack condition, are in greater demand; as a result, preparation practices at the mines have had to be revised so that, in many instances, lump coal is being crushed to meet the demand for stoker coal. This situation in turn has necessarily resulted in a realignment of price schedules for the different sizes. One of the first underfeed stokers small enough for domestic use was developed at Seattle, Wash., in 1912; in 1916, a small overfeed stoker was developed at Seattle. These two types are generally considered to represent the beginning of the present domestic stoker industry in the United States. A careful inquiry as to the number of domestic stokers now installed in the Seattle area, made by C. R. Pate, who was detailed to this duty by the Works Progress Administration, indicated that probably 7,000 domestic stokers are being used in this area for residential heating. Most of these stokers axe of the overfeed type, although in the past 2 years the underfeed type has made rapid gains.

Jan 1, 1938

By H. F. Yancey

The development, manufacture, and sale of small coal stokers suitable for domestic use has provided a new industry in the United States at a time when badly needed. Sales of domestic stokers have doubled each year for the past 4 years, until in 1936 probably more than 80,000 such units were put into use, According to reports of the Bureau of the Census 75,543 residential stokers mere sold in the first 10 months of 1937 by 108 manufacturers. This rapid expansion has made itself felt in the coal-mining, industry. The smaller sizes of coal, either in a sized or slack condition, are in greater demand; as a result, preparation practices at the mines have had to be revised so that, in many instances, lump coal is being crushed to meet the demand for stoker coal. This situation in turn has necessarily resulted in a realignment of price schedules for the different sizes. One of the first underfeed stokers small enough for domestic use was developed at Seattle, Wash., in 1912 in 1916, a small overfeed stoker was developed at Seattle. These two types are generally considered to represent the beginning of tie present domestic stoker industry in the United States. A careful inquiry as to the number of domestic stokers now installed in the Seattle area, made by C. R. Pate, who was detailed to this duty by the Works Progress Administration, indicated that probably 7,000 domestic stokers are being used in this area for residential heating. Most of these stokers axe of the overfeed type, although in the past 2 years the underfeed type has made rapid gains.

Jan 1, 1938

By Wilton Johnson

Native asphalt was produced in 1982 by five companies in two States, Texas and Utah. Bituminous limestone, used primarily as a paving material for street and road repair, was produced by White Uvalde Mines and by Azrock Industries, Inc., Uvalde County, Tex. Historically, gilsonite, a solidified hydrocarbon found only in Utah and Colorado, had been mined by American Gilsonite Co. and by Ziegler Chemical and Mineral Corp. from properties near Bonanza, Uintah County, Utah. During 1982, Hydrocarbon Mining Co., a subsidiary of the Oberon Oil Co., entered into a joint venture with Miocene Resources Inc. of Novato, Calif, to form Hydrocarbon Resources Co. for the purpose of mining gilsonite about 50 miles south of Vernal, Uintah County, Utah. Under the agreement, Hydrocarbon Mining contributed gilsonite-bearing properties held by lease or sublease as well as mining equipment to the venture. The property contained leases totaling 760 acres with probable reserves of 268,000 tons of gilsonite. Miocene Resources provided the partnership with a minimum of $200,000 to develop two of the leases and were to be responsible for management of the mining operations.2

Jan 1, 1983

By J. H. Holden, C. C. Shale, G. R. Strimbeck, W. S. Bowie

Electrical characteristics are presented for air in a 2 - inch pipe - type electrostatic precipitator operating under dynamic conditions at temperatures of 600 ° to 1,500 ° F and pressures of 0 to 80 psig using a negative discharge electrode . Results of this one - geometry study show that current - voltage relationships are a function of air pressure and temperature and indicate that precipitators can be used at any temperature through about 1,350 ° F over the full range of pressure . Corona starting voltage and sparkover voltage vary directly with pressure and inversely with temperature . At temperatures above 1,350 ° F use of precipitators may be limited to operations at pressures somewhat above atmospheric pressure . Theoretical derivations are presented that relate the effect of gas density on corona starting voltage and the effect of ion mobility on corona current . Deviation from the theory is noted at high current levels . Theoretical discussion is presented to explain the apparent electrical limitations for use of precipitators at high temperature , low gas density , and high corona currents , conditions at which calculated ionic velocities are extremely high . Experimental results are interpreted in terms of the theory presented . 1,500 ° F thermal ionization does not appear to be a critical factor .

Jan 1, 1963

By Yael Miron

The presence of pyrite (FeS2) in coal can cause or contribute to several problems for the coal mining industry. These problems, which include spontaneous combustion, roof falls, floor heave, and accidental explosions in coal surface mining when ammonium nitrate fuel oil (ANFO) explosives are used, result from pyrite oxidation. Pyrite oxidizes exothermically in the presence of air and moisture to form a large variety of products, including hydrated ferrous and ferric sulfates, and sulfuric acid. Some of the products are reactive chemicals and strong oxidants. The volume of many of these oxidation products exceeds the original volume of the pyrite; as a result, the adjacent coal disintegrates and its surface increases, rendering it more susceptible to oxidation. The heat from pyrite oxidation raises the temperature of the adjacent coal, accelerating the oxidation and self-heating rates of the coal. These combined chemical, physical, and thermal effects are the cause of the aforementioned problems. When ANFO is used in surface coal mines and contacts ferrous sulfate, a highly exothermic reaction ensiles. Additional hazards are fires or explosions caused by the frictional ignition of methane when the pyrite in the coal is struck by a cutting bit during mining.

Jan 1, 1994

By John J. Henn

An evaluation is presented of the Bureau of Mines process for the recovery of metal and mineral values from municipal incinerator residues. This process employs standard mineral beneficiation techniques and is operating on a pilot-plant scale of 1,000 pounds of incinerator residue feed per hour. Products from this separation process include ferrous, aluminum, and copper-zinc scrap, and colorless and colored glass. Cost estimates were prepared for four plant sizes. The estimated capital and operating costs For the four plants follow: [ ] It is assumed that the separation plant is located adjacent to a municipal incinerator. Provision is made, however, for part of the residue feed to be delivered by truck so that one large separation plant can be used for residue from more than one incinerator.

Jan 1, 1971

By J. D. Brown

The electron optics, vacuum system, and sample stage assembly for the Bureau of Mines? electron probe X-ray spectrograph were purchased. Four scanning curved-crystal spectrometers, two reflection- and two transmission-type, were designed and constructed by the authors. The reflection spectrometers are placed in a vacuum chamber for measurement of long-wave-length X-radiation. Detection, pulse-amplitude discrimination, and recording circuits are provided for the simultaneous measurement of four X-ray spectral lines. Minimum spot size is approximately 2 microns in diameter at 30 kilovolts and a sample-to-ground current of 5 x 10-8 ampere. At this voltage and current the limit of detection with reflection spectrometers is less than 0.05 weight-percent for most elements. The limit of detection for elements determined by transmission-type spectrometers, evaluated at 35 kilovolts and 5 x 10-8 ampere, is approximately 0.1 weight--percent for all elements having excitation voltages below 20 kilovolts. In general, reflection spectrometers exhibited satisfactory but poorer resolution than the transmission type, resolution of the spectrometers being limited primarily by crystal imperfections, with greater mosaic structure being introduced by the grinding process for the reflection crystals. Several applications of the electron probe X-ray spectrograph are described. Analysis of a uranium-steel is discussed in detail to illustrate calculation of composition from measured X-ray intensities.

Jan 1, 1962

By Mark P. Meyer

This U.S. Bureau of Mines publication presents salient information in abstract form on 247 coal deposits in Alaska. Coverage includes currently producing deposits and deposits that appear to have commercial production potential. Data arc taken from coal properties identified by the U.S. Bureau of Mines minerals availability program and by a literature search. Infrastructural and institutional factors affecting coal development in Alaska are also discussed.

Jan 1, 1987

By C. W. Owings, J. J. Forbes

"Although coal-mine explosions rank third among causes of underground fatalities, they receive more wide-spread attention than any other accidents in mines because frequently many persons lose their lives in a single disaster. Each bituminous coal-mine explosion endangers the lives of approximately 100 persons--the average number employed underground in a commercial mine. A critical analysis of coal-mine explosions in a restricted district gives a cross-section of relative existing explosion hazards, of common causes of ignitions of gas and dust, and of effective prevention measures. The Safety Division of the United States Bureau of Mines is collecting data on coal-mine explosions in the various States, and this circular is one of a series analyzing the causes and recommending methods for thy prevention of similar occurrences,The data on this circular are based on records of the United States Bureau of Mines and the West Virginia Department of Mines. Unfortunately practically all of the early records were destroyed by fire in the State House at Charleston, W. Va.; the remaining records were made available to the authors by N. P. Rhinehart, chief of the Department of Mines, and his cooperation is gratefully acknowledged.The earliest available reference to coal in West Virginia is that made by John Peter Lally who in 1742 found ""a great plenty of coals"" near a river later called Coal River. In 1809, Nicholas Roosevelt found coal along the Ohio River and used it on the New Orleans, said to have been the first steamboat west of the Allegheny Mountains. In 1810, Conrad Cotts opened a mine near Wheeling and sold coal for domestic purpose in 1812, a mine was opened on the Ohio River opposite Mason City and produced 1,200 bushels of coal that year. In 1840 the total West Virginia coal production was 298,691 tons; in 1863, the production had increased to 444,468 tons, and in 1883, to 2,335,833 tons. During this period apparently most of the coal was extracted from coal outcropping on the hillsides; little danger of gas ignition existed at that time, but explosions from blown-out shots occurred frequently. On February 22, 1383 the West Virginia legislature enacted legislation providing for a mine inspector to inspect the mines of that State, to prevent mine accidents, and to insure properly ventilated mines.In a special report to the Governor on December 31, 1884 the Inspector of Mines reported:We have 5 shafts, in 4 of which there is more or less gas; and in 1 of our drift mines there was an explosion on the 27th day of March 1880, whereby 2 men were killed and a boy badly burned.Table 1 lists 287 explosions in West Virginia coal mines. Several early explosions were listed in the annual reports of the West Virginia Department of Mines as ""blown-out shots"" or ""powder explosions"". The injuries usually were described; explosives accidents have been eliminated from these and other available data, and only those in which dust or gas were involved have been included in this paper as explosions."

Sep 1, 1934

By Thomas M. Barczak, Joe Bower, Jinsheng Chen

Pumpable roof supports provide an alternative longwall tailgate roof support and have grown in usage during the past few years. Heintzmann Corporation has been installing pumpable roof supports at the RAG Resources Emerald Mine in western PA since 1998, where they have provided effective roof control in their longwall tailgates. Despite the success of these supports in this application, questions remain regarding critical design issues for optimizing the use of this support technology. The support loading profile is characterized by a high initial stiffness with peak loading occurring at less than one inch of convergence, followed by significant load shedding with a post failure capacity comparable to that of wood cribbing. Therefore, the key to optimizing the support utilization is to provide sufficient load density to prevent convergence from occurring beyond the peak loading capacity. This requires an understanding of how the supports interact with the ground conditions, hence measurement of the ground reaction curve. In order to obtain this information, pumpable roof supports were instrumented to measure support loading. Roof deformation and roof-to-floor convergence measurements in the vicinity of the instrumented supports were also made. The experimental parameters for the installation were the support spacing and water-to-solids ratio of the grout, which controls the grout strength and ultimately the maximum capacity of the support. The study clearly shows that at this mine a 24-inch diameter support is fully capable of providing adequate ground control under depths of cover of 750 ft as only 50 pct of the available support capacity was utilized outby the longwall face. It was also shown that the 2.00 to 1 water-solids ratio, despite providing a slightly softer support response, is sufficient for maintaining the same degree of roof control provided by the traditional 1.75 to 1 grout mix. The 10-ft spacing of the supports did not cause any ground control problems outby the face. However, inby the face the performance of the support is degraded once the peak capacity of the supports is exceeded. It appears that the large load shedding behavior, which is characteristic of this support following peak loading, allows the immediate roof to separate. When this happens, the support is unable to regain control of the roof in time to prevent failure of the immediate roof beam.

By Peter Grandone

"INTRODUCTION The Bureau of Mines, recognizing the importance of knowing the evapor¬ation losses of aviation gasoline as larger quantities of this material must be stored, has made studies at a large refinery in the Texas Panhandle area during the past 13 months to determine the magnitude of the losses, by evaporation, under different storage conditions. Proper storage of aviation gasoline is very important, not only because large supplies are being stored for military use but because the specifications to which his fuel must conform are very rigid. Aviation gasolines that conform present-day specifications are blended from base-gasoline stocks (in some instances relatively pure hydrocarbons), each of which has different physical and chemical characteristics. Consequently, partial loss of any one of the more volatile components from the blended fuel results not only in material loss of the blended fuel but also may affect the characteristics or performance of the gasoline. One characteristic that has considerable influence or the vaporization tendency of gasoline is vapor pressure; and although the vapor pressure of aviation gasoline usually is lower than that of average commercial motor fuel, the quantity of certain components having relatively higher vapor pressure is greater in aviation gasoline, so that under prolonged storage the evaporation loss of these components may be appreciable."

May 1, 1943

Volume 2 presents the results of studies of Phelps Dodge Corporation's tailings embankments numbers 1West and 2 West, at Morenci, Ariz. The work involved compilation and description of pertinent factors relating to the physical features and operational characteristics of the facility, including information on embankment construction practices; investigation and research of the general geologic and seismicity characteristics of the site and vicinity; limited field exploration and materials sampling and testing at the site; installation and limited monitoring of piezometers, surface movement markers, and slope indicator casing; limited laboratory testing of materials to evaluate the basic index and engineering properties of the embankment and tailings materials; selected engineering analyses of the embankment for various types of potential "failure" conditions; and includes appendices.

Jan 1, 1974

By Robert E. Hershey

1. Estimates of reserves were made for three coal beds in Hamilton County the - Lantana, Sewanee, and Richland. Nine coal beds have been mined at one time or another in the county, but not enough information was available to estimate reserves in any beds other than the three given. 2. Known measured and indicated reserves for all beds, based on a minimum thickness of 14 inches and on 1,800 short tons per acre-foot of coal in place, are estimated to be 53 million tons as of January 1, 1954. Of this total 35 million tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics were insufficient for making an estimate conforming with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove re-serves in these areas, such reserves should be added to the total estimated reserves determined by this investigation.

Jan 1, 1956

By Paul M. Tyler

Hafnium appears to be among the more abundant of the newly discovered elements . Though quite widely distributed in nature , its compounds chemically so resembled those of zirconium , its sister element , that it escaped detection until 1923 , when Coster and Hevesy announced the discovery of the element , to which they gave the name of " hafnium " , from Hafniae , the Latin name for Copenhagen , where their research work was performed . Hafnium has so far been found only as a minor constituent of zirconium minerals . Zirconium as an element was discovered more than 140 years ago , but only a few unimportant uses were found for the metal or its compounds until some 18 years ago ; it is still classed among the rarer commercial metals . It is not surprising , therefore , that hafnium has not yet found a definite place for itself in industry . Nevertheless it has commanded a considerable interest among scientists ; and in 1930 some 70 grams of perfectly pure oxide of hafnium were prepared in Europe . A commercial future for hafnium is already glimpsed in the radio industry , and its high melting point and electronic emissivity have already led to the taking out of patents for its use in radio tubes and incandescent electric lamp filaments and for the cathode surfaces of devices such as X- ray tubes and rectifiers .

Apr 1, 1931

By P. B. Altringer

Searles Lake, CA, contains the largest known domestic tungsten resource. The brines in this near-dry lake bed, located in the Mojave Desert 130 mi northeast of Los Angeles, contain an estimated 135 MMlb of tungsten. However, the low concentration of tungsten (0.080 g/L W03) in the supersaturated brine makes selective tungsten extraction very difficult. Although many brine chemicals are extracted from the lake, tungsten recovery was an elusive goal prior to Bureau of Mines development of an ion-exchange technique. This publication describes the Bureau process. The following subjects are ad-dressed: ? The Searles Lake tungsten resource. ? General problems associated with tungsten recovery. ? Bureau research objectives. ? Synthesis of ion-exchange resins. ? Development of a two-stage ion-exchange tungsten extraction and concentration procedure. ? Product recovery and purification. ? Economic evaluation. Flowsheets for recovering three products (calcium tungstate, sodium tungstate, and tungstic oxide) are presented and evaluated, as well as a summary of the research effort and potential applications.

Jan 1, 1985

By John C. Machisak

INJURY experience and employment data for the nonmetal mining industry in the United States are presented for the calendar year 1958. Statistical tables 6 to 12 give detailed information on injuries and employment at nonmetal mines. Data for nonmetal mines are presented separately from those for nonmetal mills, tables 23 29. The Bureau is authorized to send questionnaires to the nonmetal industry for their voluntary submission on of injury and employment experience at their operations. As this information contributes to the promotion of safety in the nonmetal mining industry, every effort has been made to make these questionnaires as complete as possible.

Jan 1, 1962