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By Ivan L. Nichols

Tailings dumps at Mercur, Utah, contain about $7 million worth of gold in 3.5 million tons of mill tailings assaying about 0.07 ounce of gold per ton. Commercial mining and milling at Mercur ceased in 1942. To determine whether improved technology was now available that might permit economic reprocessing of the Mercur dumps, the Bureau of Mines probed for a low-cost method that would be applicable to these tailings. A composite sample prepared for laboratory studies assayed 0.062 ounce gold per ton. About 10 percent of the gold occurred as a water-soluble cyanide. Conventional cyanide leaching dissolved 32 percent of the gold, and hot, strong cyanide solution dissolved 42 percent. Results were not improved by pretreatment with acids, bases, or oxidants. After expensive preroasting, gold recovery by cyanidation was increased to 65 percent. The simple procedures were ineffective, and more effective procedures were too costly for economical processing of Mercur tailings.

Jan 1, 1970

By G. T. Lineberry, W. J. Wiehagen

A Paradigm Shift As market economists, mine managers are interested in "staying in business" and even "prospering." Bottom-line results are the "order of the day." Concern for bottom-line results invokes questions such as: How much was produced? At what cost? And, was anyone injured? While these questions will always carry everyday emphasis at the mine, they are fundamentally lacking in that they often appear, especially to lower levels of management and to the production worker, as preeminent concerns. Driven by market economics, many organizations have decentralized, outsourced, downsized, restructured, and formed new coalitions. Investments in new technology and concentration on productivity have been part and parcel with these changes, contributing to improvements in both safety and efficiency. A reason for (and, perhaps a result of) these improvements has been the development of a highly experienced and flexible work force. These changes in mining present an interesting opportunity to modify a few paradigms about work life in general, and perhaps a few paradigms about how we invest in the miner, in particular. Studying these issues now might offer some interesting opportunities for the future, as the foundations for the next generation of mine workers are laid. With the average "experienced" U.S. miner five to fifteen years from retirement, perhaps a key determinant of future success in the world market might be how well we make the transition from today's work force to the work force of tomorrow. We can ill afford to wait a few more years to tap into the special knowledge residing within a veteran mining work force. The WCPM work Crew Performance Model, see pp. ) is one approach to defining, capturing, and transferring this expertise.

The purpose of the contract was to develop an improved coal mine dust sampler whose electrical-to-mechanical energy conversion efficiency would be superior to that of the presently available equipment. The electrical to (pressure) X (volume) conversion efficiency directly affects the size and weight of the air samplers. At least half of the mass of present equipment is composed of the rechargeable batteries. Any increase in efficiency will allow this mass to be reduced or the flow rote to be increased.

Jan 1, 1974

By Victor Erickson

ECONOMIC recovery, which began in 1958, carried through into 1959 but was somewhat retarded by the 116-day steel strike beginning in July 1959. Recovery and economic growth increased production and consumption of mineral fuels 3 percent above 1958. The increase was accomplished despite a drop of 26 percent in coal exports. Prices remained constant during the year so that the value of production and consumption also increased 3 percent over 1958. Stocks in the hands of producers at yearend were little changed from the supply at the beginning of the year. Employment in the field of mineral fuels decreased 6.4 percent from 1958. Average hourly earnings were up 7 percent, and average hours worked were up 5 percent, with the result that weekly earnings gained 11.8 percent. Internal freight rates were relatively constant, but ocean tanker rates declined both in 1958 and 1959 from the high rates charged during the Suez crisis. The index of major input expenses decreased for anthracite, held constant for bituminous coal, and increased for petroleum. The index of labor cost per dollar of product and per ton of product declined again in 1959 to a new low in anthracite and bituminous-coal mining industries.

Jan 1, 1960

By S. R. B. Cooke, F. D. DeVaney

"INTRODUCTION The potash mineral receiving the most attention in the newly discovered. New Mexico-Texas potash district near Carlsbad, N. M. is sylvite (potassium chloride). Sylvite contains more potassium than any other mineral. Merchantable high-grade deposits have been found, and those of lower grade may be enriched to a high degree of purity by refining methods. Deposits containing sylvite were the first to be developed and axe the only ones being mined.However, many other minerals that contain potash occur in the salt beds of the Carlsbad District. Of these the more important are polyhalite, carnallite, langbeinite, leonite, and kainite. The nature of the deposits and their mineralogy have been described in detail by members of the United States Geological Survey. 4/Langbeinite, although not so abundant in these deposits as carnallite and has particular interest because the potash is in the form of the sulphate and as such commands a premium in terms of K20 unit. This is explained by Fox and Turrentine 5/, who state:"

Feb 1, 1936

By A. R. T. Denues

Liquid oxygen explosives are ordinarily made from a carbonaceous absorbent and from liquid oxygen of high purity. These explosives have a limited but definite field of usefulness; their properties have been described in the literature, which includes several publications of the Bureau of Mines, the most recent dealing with fire-retardant treatments.3/ It seems generally conceded that the outstanding hazards in the use of these explosives are their high inflammability and their relative sensitivity to mechanical action. Each of these topics has been studied, and some interesting practical results have been obtained. Treatments have been described[7] that render liquid-oxygen explosives prepared from granular carbonaceous absorbents practically immune to the action of igniting agents representing or exceeding practical hazards in violence.

Jan 1, 1941

By A. R. T. Denues

[Liquid oxygen explosives are ordinarily made from a carbonaceous absorbent and from liquid oxygen of high purity. These explosives have a limited but definite field of usefulness; their properties have been described in the literature, which includes several publications of the Bureau of Mines, the most recent dealing with fire-retardant treatments.3/ It seems generally conceded that the outstanding hazards in the use of these explosives are their high inflammability and their relative sensitivity to mechanical action. Each of these topics has been studied, and some interesting practical results have been obtained. Treatments have been described that render liquid-oxygen explosives prepared from granular carbonaceous absorbents practically immune to the action of igniting agents representing or exceeding practical hazards in violence.]

Jan 1, 1941

Pillars with width to height ratios of less than 1.0 are frequently created in underground hard rock mines. The strength of slender pillars can be estimated using empirically developed equations. However, the equations can provide variable results when the width-to-height ratios approach 0.5. This paper investigates some of the issues affecting pillar strength at low width-to-height ratios in hard brittle rock. The investigation includes an evaluation of empirical pillar strength data presented in the literature and observations of pillar performance in underground limestone mines in the eastern United States, supplemented by numerical modeling in which failure processes and sensitivity of slender pillars to variations in rock mass properties are evaluated. The results showed that the strength of slender pillars is more variable than that of wider pillars. The numerical model results demonstrated the increasing role of brittle rock failure in slender pillar strength. The absence of confinement in slender pillars can result in a fully brittle failure process, while wider pillars fail in a combined brittle and shearing mode. The onset of spalling in slender pillars occurs at or near the ultimate strength, while this is not the case for wider pillars. Slender pillars are shown to be more sensitive to the presence of discontinuities than wider pillars, which can partly explain the increased variability of slender pillar strength. Two examples are presented, which illustrate failure initiation by brittle spalling and the sensitivity of slender pillars to the presence of discontinuities.

By Paul B. Harder

Round Mountain Gold (RMG) in cen­tral Nevada, reports that over a nine-year period and a million operating hours, its fleet of 150-ton and 190-ton haul trucks has averaged better than 93% availability, with some of the trucks approaching 70,000 operating hours. Repair costs have been far below industry averages. Mine operations manager Pete Kesl credits the high availability and low repair costs to a succession of Product Support Agreements between RMG and Caterpillar dealer Cashman Equipment. He adds that good equipment and a high level of trust and co­operation between all parties to these agreements have been essential to their success at Round Mountain.

Jan 1, 1998

By Edward D. Thimons

The Bureau of Mines has developed a damage-resistant brattice, intended for use as a stopping in locations where blast damage to stoppings is a problem, the roof is relatively flat, and the differential pressure across the stopping is not high. Damage-resistant brattices consist of a series of vertically hung brattice panels joined to each other by Velcro connections that improve the airtightness of the brattice. When the brattice is subjected to strong blast forces, the Velcro connections peel apart, allowing the panels to open without incurring damage. The Velcro connections can then be resealed in a matter of minutes. A preliminary test in the Bureau's Safety Research Mine and subsequent long-term testing at the White Pine copper mine in Michigan and the Retsof salt mine in New York show that damage-resistant brattices withstand blasting better than conventional stoppings, while still performing as efficient air barriers when the Velcro connections are sealed.

Jan 1, 1978

By N. F. LeJeune, Earl C. Lane

This is the third of a series of reports on a survey of petroleum prod- ucts manufactured on the Pacific Coast from California crude oils. California crudes differ in many characteristics from the petroleum produced in the other parts of the United States, and the claim has been made that some of the present Federal Specifications for petroleum products tend to discriminate against Cali- fomia products. The purposes of the present survey are to determine what par- ticular specification requirements Califomia petroleum products characteristical ly fail to meet, how widely the products deviate from these requirements, and if possible to show whether the fault lies with the specifications or the products, or along what lines investigation to determine this question should proceed. The first report of the series gave the physical and chemical properties of the samples of gasoline and mineral spirits. A second report**, gave the physical and chemical properties of samples of lubricating oils. The present report deals entirely with burning and fuel oils. The refin ing companies have continued their very cordial and helpful cooperation. Seven samples of kerosene, four samples of Diesel fuel and eight samples of fuel oil were obtained. The methods of analysis used are those adopted by the Interdepartmental Petroleum Specifications Committee, published by the Bureau of Mines in Technical Paper No. 323. The specifications used for corparison are those officially adopted by the Federal Specifications Board for the use of the various Depart- ments and Independent Establishments of the Government, effective February 3, 1923, and published by the Bureau of Mines in Technical Paper No. 323, Part 1. Specific gravity, degrees A.P.I., viscosity and other special tests al- though not required by the specifications have been given for comparison. All temperatures are recorded in degrees Fahrenheit. Tables have been prepared giving data on physical and chemical propertios of the individual samples. Before each table the classification and specifica- tions for the particular class of oil considered in the table are given. Follow- ing each table, brief notes show wherein samples deviate from specification re- quirements.

Aug 1, 1923

By W. H. Schiffbauer

NIOSH has developed an active proximity warning system called HASARD (Hazardous Area Signaling and Ranging Device) for warning workers as they approach known dangerous areas around heavy mining equipment and other dangerous work zones. HASARD is composed of a transmitter and a receiver. The transmitter generates a 60-kHz magnetic field using one or more wire loop antennas. Each antenna is adjusted to establish a magnetic field pattern for each hazardous area. The receiver, worn by the worker, is a magnetic field strength meter. The received signal is compared against preset levels which are calibrated to identify levels of danger. The receiver outputs can include visual, audible, and vibratory indicators and it can also be made to disable machine functions. HASARD was field tested on a Joy 12 continuous miner, a Komatsu 210 M Haulpak, and on a highwall launch vehicle. Slight modifications were made for each application. HASARD provided warnings as designed and proved to be rugged enough to withstand the harshest of production environments.

By G. W. Jones

In a previous report results were given and a method outlined whereby from a knowledge of the composition of the natural gas and of the inflammability limits of the individual constituents composing the natural gas, the limits of inflammability of natural gas and air mixtures could be closely calculated. This method is based on the application of Le Chatelier's law as modified by Coward, Carpenter and Payman, to apply to a mixture of any number of combustible gases. This law must not be used indiscriminately, because many exceptions have been found. For example, when ethylene, acetylene, hydrogen sulphide, or chlorinated hydrocarbons are present the law may not hold. For a discussion of the rally exceptions which have been found, reference should be made to a report by Coward and Jones. Before this method can be used the inflammable limits of the individual constituents must be known. Also, the composition of the complex combustible mixture, and representative mixtures besides, must be tested both experimentally and by calculation to prove whether Le Chatelier's law may be applied.

Jan 1, 1933

By D. R. Mathews

The Bureau of Mines investigated the effects of tungsten and chromium, separately and combined, on improving the mechanical properties and oxidation resistance of vanadium. Binary and ternary vanadium-base alloys were prepared and tested for oxidation resistance and tensile strength. Softening occurred with less than 1 weight-percent of either tungsten or chromium, followed by strengthening with higher alloying contents. Vanadium alloys containing up to 9.8 weight-percent chromium or 14.1 weight-percent tungsten were more resistant to oxidation in air at 600° C than unalloyed vanadium. For the alloys with 12.20 weight-percent chromium or 14.56 weight-percent: tungsten, the maximum concentrations used, the lower yield strengths were about twice that of 38,600 psi for the unalloyed vanadium. Recrystallization temperatures for these alloys were 100 and 150° C higher, respectively. Alloys containing both chromium and tungsten had properties similar to those of the vanadium-tungsten alloys.

Jan 1, 1967

By Stephen A. Swan

Bureau of Mines research has not included analyses of mining dredge safety since 1948. Because of the increasing use of dredges, 63 fatal accidents and several hundred nonfatal injury accidents involving dredges were examined. Also, 31 working dredges and 3 dredge manufacturers were visited to acquire qualitative information. Drowning accidents represented 59 pct of the fatalities and are delineated in detail. Also, countermeasures against other hazards are discussed.

Jan 1, 1985

By G. W. Jones

"INTRODUCTION In a previous reports results were given of a manhole investigation carried out over a period from June,- 1929, to July, 1930, in cooperation with the Edison Electric Illuminating Co. of Boston, Mass., to determine the general hazards of combustible gases and vapors in manholes and other underground openings owned by this company. Considerable time was spent in this initial investigation in developing a suitable detector for determining the range of explosibility of the gases found in manholes. About 17,000 tests have been made with the detector since the investigation was started and its utility has been verified and its accuracy checked, by having complete analyses made of such samples that showed combustibles present equal to or above 25 per cent of the lower explosive limit, and those found deficient in oxygen.The initial investigation made in 1929 and 1930 demonstrated that the detection, control, and elimination of combustible hazards in manholes can best be obtained by a close cooperation of the interested parties through a systematic and continuous inspection of manholes, under proper supervision.COOPERATIVE INVESTIGATI0N DURING 1931The investigation carried out during the year 1931 has been along lines similar to that conducted during 1929 and 1930. In the present investigation the Edison Electric Illuminating Cc. of Boston and the Boston Consolidated Gas Co., have cooperated with the Bureau of lanes. The Boston Consolidated Gas Co. serves a major part of the territory under discussion with gas, but the tests covered the Edison territory irrespective of the gam company furnishing manufactured gas. A test crew consisting of two men, one an employee of the Consolidated Gas Co. and one an employee of the Edison Electric Illuminating Co., has been continuously employed during the year in the testing of games in manholes served by the Edison system. The test crew was under the direct supervision of John Campbell, superintendent of the special service department of the Edison Electric Illuminating Co., and F. M. Goodwin vice president of the Consolidated Gas Co.As in the previous investigation, all manhole tests were given test numbers. The test data sheets on which the information regarding the tests were recorded were prepared in triplicate, one copy going to the Edison Company, one going to the Gas company, and the third to the Bureau of Mines at Pittsburgh. These test data sheets were then filed (1) according to the town, (2) the street location, and (3) the manhole number; in this way a complete record pf each manhole tested was immediately available. A specimen test sheet is given below."

Sep 1, 1932

By John J. Sammarco

The U.S. Bureau of Mines has developed a regulated, intrinsically safe, rechargeable power supply for portable electronic equipment for underground use. The regulated output is ideal for microprocessor power requirements and is suited for operation in hazardous environments. Two rechargeable, sealed batteries are contained within the power supply. Provisions are made to use an external source of power if these batteries fail. Provisions are also made to charge these internal batteries when needed. The circuit is composed of three main circuits: the main regulator circuit, the input protection circuit, and the output protection circuit. The main regulator circuit provides remote voltage sensing, current sensing, fault monitoring, and internal thermal protection. The input protection circuit checks for excessive input current and low battery conditions. The output protection circuit contains two overvoltage detection devices. Schematics, a parts list, and a calibration procedure are provided in this report to enable readers to fabricate the power supply.

Jan 1, 1989

By Wilton Johnson

The Bureau of Mines study indicates that land utilized by the mining industry for mineral extraction and processing from 1930 through 1980 amounted to 5.7 million acres, or 0.25 percent of the land mass in the United States. Land reclaimed by the industry during the same period was 2.7 million acres, or 47 percent of the land utilized. Land use by the mining industry includes surface land used for excavation or mining, for waste from underground mining, and for wastes from milling or processing operations. Data on land use for disposal of overburden waste from surface coal mines and on areas affected by subsidence associated with underground mining are included for the period 1930-71 only. The 10 leading States in total land used for mining over the 51-year period were, in decreasing order, Pennsylvania, Kentucky, Ohio, Illinois, West Virginia, Florida, Indiana, California, Alabama, and Missouri. Seven mineral commodities accounting for 92 percent of land use are, in decreasing order, bituminous coal, sand and gravel, stone, phosphate rock, clay, copper, and iron ore, all predominately surface mined. Bituminous coal production was responsible for nearly half of the total area utilized. Reclamation of mined lands and waste disposal sites over the reporting period was largely on lands utilized in mining bituminous coal; 75 percent of the land used for bituminous coal production was reclaimed.

Jan 1, 1981

By F. Garcia, J. Cervik

The cross-measure borehole technique has been shown by the Bureau of Mines to be an effective method of controlling methane liberated by fracturing the roof strata in longwall gobs where overburden is less than 750 ft (229 m). Boreholes are drilled into roof strata before mining operations affect the roof strata. Longwall mining fractures the roof strata and releases methane from source beds. Surface exhausters or vacuum pumps are used to draw the gas to the surface through an underground pipeline and vertical exhaust hole. The captured methane is thus prevented from entering the mine's ventilation system. About 71 pct of the methane produced by longwall mining in the Lower Kittanning Coalbed was captured by the cross-measure boreholes. Borehole spacing is an important factor affecting the performance of the technique. Interference tests and measurements of methane flows in return air indicate borehole spacing in the Lower Kittanning Coalbed should be limited to about 200 ft (61 m) except on the first 600 ft (183 m) of the longwall, where spacing should be reduced to about 100 ft (30 m) to capture the large quantities of methane released when the first large roof fall occurs. Comparisons between measured and calculated gas pressure differentials on boreholes indicate borehole length can be reduced from 280 to 140 ft (85 to 43 m), which reduces drilling costs significantly. Additional experimentation is necessary to verify the calculations.

Jan 1, 1985

By M. A. Trevits, J. E. Urosek, A. C. Smith, M. P. Valoski

The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), is conducting research to test, evaluate, improve or modify coal mine fire-fighting strategies and methodologies through large-scale tests. Since wood is the second most abundant fuel available during a coal mine fire, it was decided that series of large-scale wood crib fire tests were needed to measure the products of combustion and to observe the capability of commonly available direct application fire suppression equipment, namely, fire extinguishers, water and gas-enhanced foam. This paper discusses the wood crib fire tests, provides insight into the products of combustion and describes observations made during the application of the fire suppression agents.