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By David C. Oyler, Winton J. Gale, Jinsheng Chen, Christopher Mark

A collaborative project between RAG Emerald Mine, NIOSH, and SCT Operations was conducted to investigate ground behaviour, reinforcement performance, and stress redistribution in a coal mine entry subjected to a severe horizontal stress concentration. Field measurements indicated that the stresses applied to the study site nearly doubled during longwall mining, resulting in roof deformations extending to a height of 4.8 m (16 ft) above the entry. This paper focuses on the computer simulation that was undertaken to provide more insight into the roof behaviour and rock bolt interaction during mining. The model’s input rock properties were derived from extensive laboratory testing, and the model itself simulated a broad range of failure mechanisms. The effects of different bolt patterns on roadway behaviour were evaluated. Comparison between the model results and the field measurements indicated that that the model effectively simulated the critical elements of the actual roadway’s behaviour. With the confidence gained, the model was used as a baseline for additional simulations that evaluated the expected performance of alternative roof support systems. The study will also provide a benchmark data set for future applications of numerical modelling to U.S. coal underground mining.

By S. J. Hussey

A jig tailing with gold content ranging from 0.33 to 0.43 oz/ton was leached in weak cyanide solution with extractions of up to 97 pct in 24 hours. By countercurrent batch leaching studies and laboratory pilot plant operation, minus 10- plus 20-mesh and minus 6- plus 16-mesh coconut carbon were loaded to 700 oz/ton of Au. Minor silver in the ore reported in the carbon in amounts of up to 100 oz/ton. Gold adsorption rate data and an equilibrium adsorption curve for minus 10- plus 20-mesh carbon at ambient temperatures were developed and used in the successful application of a cascade design theory. The work was performed as a part of the overall Bureau of Mines research effort to help maintain an adequate domestic supply of metals by making improvements in mineral-processing technology.

Jan 1, 1979

By C. M. McCulloch

Examination of several coalbeds in Walker County, Ala., Cambria, Greene, and Fayette Counties, Pa., and Raleigh and Wyoming Counties, W. Va., indicates that cleat orientations are similar throughout a vertical sequence of strata. Studies of cleat orientation were carried out in underground mines that are operating in separate coalbeds vertically above one another. The data show that over a vertical separation of 100 to 400 feet, the average difference in coal cleat orientation between mines is 04° for the face and 08° for the butt cleat. Variations of coal cleat direction between coalbeds examined in strip-mined areas show similar values. Cleat orientations measured at outcrops agree well with the directions measured underground, suggesting that the amount of vertical separation between coalbeds has little effect on the resulting differences in cleat directions. The largest variation of cleat directions between adjacent coalbeds occurs where a large horizontal distance separates two sample locations. Cleat orientations for deeper coalbeds are most reliable where the data are taken from directly above.

Jan 1, 1976

By Suzann C. Ambrosio

The mineral industry in Burundi continued to be a minor contributor to the 1980 gross domestic product (GDP) estimated at $293 million in constant 1970 prices.2 Mineral export revenues, primarily from cassiterite, increased by a factor of 15 between 1979-80, reaching approximately $434,000 by yearend 1980. Gold, bastnasite, colombite-tantalite, and wolfremite continued to be exploited on a small scale, using manual and semimechanical methods. Despite a sharp decline in mining activities during 1979, attributed to a lack o? profitability and shortage of construction materials, the mining sector exhibited signs of recovery during 1980. The mineral exploration budget grew 32% over 1979 levels and was equivalent to approximately $42,000 in 1980. In addition, the Burundi Geographical Institute (IGE BU) was created in September 1980 and given responsibilities to collect cartographic, topographic, hydrogeologic, and other geomorphological data., SONIBUROM, the Burundian and Romanian Government joint mineral corporation, conducted mineral deposit inventories during 1979-80 and has been charged with exploiting some of these as yet unspecified resource areas. Another Burundian-Romanian effort, called Mabaya-Butahana, was initiated to search for gold deposits. Meanwhile on the Ruzizi plain, alluvial gold prospecting, with an estimated grade between 0.2 to 1.0 gram per ton, was carried out on a small scale.

Jan 1, 1982

By E. C. Lane

The motor gasoline that is being marketed in the United States this winter (1928-29) is slightly more volatile than that gold a year ago. This characteristic is shown by a slight lowering of the distillation temperatures, particularly at the average initial and 20 per cent boiling points. Daring the past mine and a half years the Bureau of Mines has made semi annual surreys of the gasoline marketed in the United States; the Survey just completed is the nineteenth in the series. The 12 cities in which samples have been collected were chosen as representative of the more important marketing territories, as it was obviously impracticable to obtain a sample of every gasoline sold in the entire country.

Jan 1, 1929

By D. E. Hirsch

A systematic procedure for separation, characterization, and semiquantitative analysis of high-boiling petroleum distillates was developed by the Bureau of Mines and applied to a 370° to 535° C distillate of Wilmington, Calif., crude oil. Separation procedures employed were isothermal and molecular distillation, chemical treatment, silica-alumina adsorption, and gel permeation chromatography. Characterization and analysis were accomplished by gel permeation chromatography correlations and mass and nuclear magnetic resonance spectrometry. These data should be useful in improving petroleum processing and utilization and in achieving the energy conservation inherent therein.

Jan 1, 1974

By David S. Yantek, Paul Jurovcik, Eric R. Bauer

Workers in coal preparation plants, where vibrating screens are significant noise sources, are often exposed to sound levels exceeding 90 dB(A). The National Institute for Occupational Safety and Health, a major coal company, and a vibrating screen manufacturer conducted a cooperative study of vibrating screen noise. Rubber isolators reduced sound levels by 1 dB. Urethane screen panels did not reduce sound levels in this case. Drive noise was determined to be the dominant noise source on the screen. Damped side plates reduced vibration levels on the screen sides by 1 to 7 dB(A). Detailed results of the study are presented.

By Vijia K. Karra, John J. Sammarco, Robert Paddock, Edward F. Fries

Workers in hazardous environments such as mining are constantly exposed to the health and safety hazards of dynamic and unpredictable conditions. One approach to enable them to manage these hazards is to provide them with situational awareness: real-time data (environ-mental, physiological, and physical location data) obtained from wireless, wearable, smart sensor technologies deployed at the work area. The scope of this approach is limited to managing the hazards of the immediate work area for prevention purposes; it does not include technologies needed after a disaster. Three critical technologies emerge and converge to support this technical approach: smart-wearable sensors, wireless sensor networks, and low-power embedded computing. The major focus of this report is on smart sensors and wireless sensor networks. Wireless networks form the infrastructure to support the realization of situational awareness; therefore, there is a significant focus on wireless networks. Lastly, the “Future Research” section pulls together the three critical technologies by proposing applications that are relevant to mining. The applications are injured miner (person-down) detection; a wireless, wearable remote viewer; and an ultrawide band smart environment that enables localization and tracking of humans and resources. The smart environment could provide location data, physiological data, and communications (video, photos, graphical images, audio, and text messages).

Jan 4, 2007

By A. L. Murray

"Welfare endeavor in connection with both the metal and the coal mines of Utah has shown gratifying progress during recent years, and in most mining towns of the state, both the operators and their employees deserve much credit for the efforts put forth to better the living, working, educational and recreational conditions. Progress has been and is being made, but there are still a few important towns where purer water and better sewage disposal are pressing needs.In the older metal-mining towns that are incorporated and are independent of the mining properties operating in the vicinity, less opportunity is presented for the companies to exercise efforts looking toward improved welfare conditions than in company towns controlled by the mine operators.However, even in such towns the companies can do much to better welfare conditions, as shown by the progress in Bingham Canyon during the past several years. The Utah Copper Company has spent $800,000 since 1920, in the erection of modern brick cottages, apartment houses and the Germnell Memorial Club. The cottages and apartment houses have every convenience to be found in up-to-date city homes. The Gemmell Memorial Club erected and equipped at a cost of $175,000 was provided by the company for the benefit of the Utah Copper employees living in the canyon and has been made the recreational center for the camp. Another improvement is the $100,000 fireproof hotel built by the United States Mine of the United States Mining, Smelting and Refining; Co. in the Copperfield section of Bingham Canyon. This hotel will accommodate 105 men exclusive of hotel help and has all the conveniences of a city hotel."

Sep 1, 1925

By Ted C. Briggs

Equations for the elastic pressure distortion of the volumes of a Burnett compressibility apparatus are developed and presented in this report for volumes under internal and external applied pressures. An experimental method for the determination of the external pressure distortion coefficients is presented. Young?s modulus and the internal-pressure distortion coefficients are computed from the experimentally determined external-pressure distortion coefficients. The temperature dependence of the pressure distortion coefficients and of Young's modulus is evaluated for the temperature range 0° to 80° C.

Jan 1, 1968

As part of the U.S. Bureau of Mines (USBM) program to characterize subsidence this combination of software and hardware has been used to remotely monitor overburden response to longwall mining. Background The principle of time domain reflectometry (TDR) is being used by the USBM to monitor strata displacements induced by mining. This capability has been enhanced by the availability of cable testers with serial communication modules that allow users to get TDR records in digital form. Actual field installations involve coaxial cables that arc hundreds of meters long, and the many records obtained when monitoring such long cables on a daily basis motivated development of software to view interactively and compare waveforms and to analyze signature changes. Time domain reflectometry (TDR) was developed in the 1960's as a method to locate discontinuities in coaxial transmission cables. The concept has been extended to measurement of properties of materials into which probes are embedded, such as water content of soil, and evaluation of coaxial cable dielectric behavior. This technique was adapted by the USBM in 1975 for use in checking the movement of rock during underground mining. Coaxial cables are grouted into a rock mass that is expected to cave, and progressive rock movement causes the cable to deform. Consequently, there is a progressive change in cable electrical properties that produces changes in TDR pulse reflection signatures. TDR technology has been advanced by Northwestern University to the point where it is now possible to distinguish shear deformation from tensile deformation, and to quantify rock mass displacements, by analyzing these changes in TDR signatures.

Jan 1, 1993

By Michael S. Wieland

The work-principle from thermodynamics was used to formulate a model for predicting toxic fumes from mining explosives in underground chamber tests, where rapid turbulent combustion within the surrounding air noticeably changes the resulting concentrations. Two model constants were required to help characterize the reaction zone undergoing rapid chemical transformations in conjunction with heat transfer and work output: a stoichiometry mixing fraction and a reaction-quenching temperature. Rudimentary theory with an unsteady uniform concentration gradient was taken to characterize the combustion zone, yielding 75% for the mixing fraction. Four quenching temperature trends were resolved and compared to test results of ammonium nitrate compositions with different fuel-oil percentages (ANFO). The quenching temperature 2345 K was the optimum choice for fitting the two major components of fume toxicity: carbon monoxide (CO) and total nitrogen oxides (NOx). The resulting two-constant model was used to generate comparisons for test results of ANFO compositions with additives. Though respectable fits were usually found, charge formulations which reacted weakly could not be resolved numerically. The work-principle model yields toxic concentrations for a range of charge formulations, making it a useful tool for investigating the potential hazard of released fumes and reducing the risk of unwanted incidents. Keywords: Toxicity; Fumes; Explosives

CESIUM metal production increased sharply in 1963. Domestic Production.--Cesium metal was produced by The Dow Chemical Co., Midland, Mich., MSA. Research Corp., Callery, Pa., and by Penn Rare Metals, Inc., Revere, Pa. American Potash & Chemical Corp., Trona, Calif., produced some combined cesium and rubidium. This company, Penn Rare Metals, Inc., and Rocky Mountain Research, Inc., Denver, Colo., produced various cesium compounds. Complete production data on cesium and rubidium and their compounds were not available for publication. Consumption and Uses.-Substantially more pollucite was consumed to produce cesium metal and compounds in 1963 than in 1962 but the overall consumption of pollucite continued to be small.

Jan 1, 1964

By Gerald J. Joy, Paul J. Middendorf

This study examines the patterns and trends in noise exposure documented in data collected by Mine Safety and Health Administration inspectors at U.S. coal mines from 1987 through 2004. During this period, MSHA issued a new regulation on occupational noise exposure that changed the regulatory requirements and enforcement policies. The data were examined to identify potential impacts from these changes. The overall annual median noise dose declined 67% for surface coal mining and 24% for underground coal mining, and the reduction in each group accelerated after promulgation of the new noise rule. However, not all mining occupations experienced a decrease. The exposure reduction was accompanied by an increase of shift length as represented by dosimeter sample duration. For coal miners exposed above the permissible exposure level, use of hearing protection devices increased from 61% to 89% during this period. Participation of miners exposed at or above the action level in hearing conservation programs rapidly reached 86% following the effective date of the noise rule. Based on inspection data, the occupational noise regulation appears to be having a strong positive impact on hearing conservation by reducing exposures and increasing the use of hearing protection devices and medical surveillance. However the increase in shift duration and resulting reduction in recovery time may mitigate the gains somewhat.

By E. J. White

Data from oil well logs and core analyses were used to quantitatively evaluate formation porosity and water saturation of heterogeneous carbonates and to study the pore geometry and performance characteristics of cores from these formations. Logs and cores from the Madison limestone from 233 wells in three fields in the Williston basin were used in the investigation. A comparison of log and core analyses shows that log porosities are consistently larger than core porosities, and the differences are correlatable with core porosity ranges. Water saturations from logs are usually smaller than the corresponding core saturations by summation of fluids, but the difference is attributable to mud filtrate invasion into the cores during drilling. Petrophysical studies show that the low permeabilities and high residual water saturations in these reservoir rocks are due to their fine crystalline texture and complex pore geometry (heterogeneity). It is concluded that both log and core analyses must be used for reliable evaluation of these carbonate formations.

Jan 1, 1971

By John J. Sammarco

As part of a project to automate coal extraction, computer control of a continuous mining machine test bed has been developed and tested by the Bureau of Mines. A computer system and control software were developed for accurate positioning of the conveyor elevation and swing, stabilizer jack, gathering head, and shear elevation. Tramming actions are also controlled by the computer. The computer system was designed to access data from sensors installed on a continuous miner and to interface with the existing control circuits of the miner. Testing in free space was used to characterize the operation of the machine. From this information, control algorithms were written and stored in the computer. The ability to control each function of the continuous miner with a high degree of accuracy and stability was successfully demonstrated in a series of tests in free space and in mining a block of simulated coal. In the mining of simulated coal, the cutting drum was instructed to position the shearer at the top of the block and shear down to the bottom under closed loop control. The cutting drum came within 0.27 in of the top and within 0.49 in of the bottom of the block for this shearing test.

Jan 1, 1988

By Edward F. Courtney

Loss of life, loss of sight, crippling injuries, and property damage nearly always result from accidents involving explosives. The severity of such accidents has prompted lawmaking bodies to pass laws concerning the transportation, handling, and use of explosives; manufacturers of explosives publish manuals 'describing explosives and practical methods of handling then; and mining companies and others who use large quantities of explosives publish rules based on actual experience for the guidance of their employees. Careless storage of explosives by thoughtless or incompetent persons, particularly if they are left where children or saboteurs have access 'to them, has led to many serious accidents. Many contractors and mining operators who use explosives are extremely careless about storing them. It is the purpose of this paper to discuss the explosive-handling practices of a large western mining company, which are considered better than most.

Jan 1, 1946

By Terry J. Close

In 1992, as part of the U.S. Bureau of Mines Idaho Land Assessment Program, the Western Field Operations Center investigated the mineral resources of the 30,300-hectare Elk Summit study area. The area is in the Clearwater National Forest, adjoining the Selway-Bitterroot Wilderness in Idaho County. Idaho. The study area is underlain by granitic and metasedimentary rocks. Associated with these rocks are road metal (stone) resources, black sand mineral placer resources, and thermal water resources. Also present are abundant sand and gravel. Two of the five sites examined during the Bureau study have road metal (stone) resources, one has black sand mineral resources, one has thermal water resources. The fifth site is a black sand mineral placer occurrence. There is no evidence of petroleum or coal resources. Idaho County records indicate that 38 mining claims, mostly black-sand placer, have been located in the study area, Twenty-three of the claims are current. Workings consist of a few pits and trenches at the placer, and two borrow pits. The only mineral commodity produced from the area was about 1,500 tonnes of stone excavated from the Savage Pass and Swamp Creek borrow pits along the Elk Summit road, north of Hoodoo Lake. The stone was used to surface the road; these stone resources will continue to be used as needed.

Jan 1, 1993

By Philip B. Lorenz

A Bureau of Mines feasibility study on the use of tracer pulses to assess the degree of fracturing in an underground formation consisted of three phases: 1. A laboratory study on sand packs and open tubes, which developed a correlation between dispersion of the pulse and size of the flow channels. 2. A test on a retort, 11 feet in diameter and 45 feet high, packed with shale rubble. Void volume was measured, but evaluation of channel size was not possible because of interference from the space unoccupied by the matrix. 3. A field test on an explosively fractured shale formation. Pressure, flow, and transit time led to qualitative estimates of fracture pattern, but quantitative detection of dispersion in the formation was overwhelmed by dispersion effects in the well.

Jan 1, 1973

By C. L. Karr

The U.S. Bureau of Mines is optimizing the design of an air-sparged hydrocyclone. This report summarizes the initial stage of the project-the prediction of collision efficiencies for use in a comprehensive air-sparged hydrocyclone model. The equations of motion are presented in nondimensional form and solved numerically for a small spherical particle passing around a larger bubble in an infinite fluid under the influence of a strong force field. Collision efficiencies are determined from the calculated particle trajectories for values of Stokes' number, K, between 0.01 and 100 and for values of the nondimensional force, W, between 0.0 and 100. These large values of K and Ware needed to model high-performance flotation devices like the air-sparged hydrocyclone; solutions for the required K and W values have not appeared in the literature prior to this study. Effects of changes in particle-to-bubble radius ratio are considered for both viscous and potential flows. The results help predict the improved recovery of fine particles when flotation is performed in a strong force field.

Jan 1, 1990