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By A. R. Taylor

The Bureau of Mines has determined the heat capacity and enthalpy values for beryllium sulfate (BeS04) throughout the temperature ranges of 10° to 300° K in an adiabatic calorimeter, and 350° to 860° K in a Bunsen-type ice calorimter, The heat-capacity data were extrapolated to 0° K, and smooth values of heat capacity, entropy, enthalpy function, and free-energy function were reported at 10-degree intervals between 0° and 300° K. The method of least squares was used to fit the enthalpy data with an algebraic equation. The equation also was used to calculate values of heat capacity, entropy, enthalpy function, and free-energy function at 50-degree intervals between 300° and 900° K.

Jan 1, 1963

By Ernesto Villaescusa, Andres Brzovic

Rock masses of the primary copper ore at the El Teniente Mine are very competent and massive. The rock mass contains almost no open discontinuities. Nevertheless, there is a high frequency network of small discontinuities coupled with widely spaced faults. A data collection campaign designed to characterize the rock structure was recently implemented. The results show that conventional analysis in terms of discontinuity frequency does not predict differences between two studied sectors. However, when an empirical definition of a weak discontinuity is applied, appreciable differences between the two sectors appear in terms of discontinuity frequency and predicted in situ block size distributions. These differences are in accordance with actual observations at the mine site. Due to the geological features of the primary copper ore, rock mass classification schemes cannot be readily applied to characterize these rock masses.

Jan 5, 2007

Identify specific sources and the relative levels of contribution of various components of longwall shearer operations to the total airborne respirable dust generated during mining. Approach A research investigation was conducted in two phases by the Bureau of Mines at five mine sites to identify specific dust sources and their relative importance during long-wall shearing operations. During phase I of the project the specific longwall mining elements identified for evaluation were: cutting, sumping, tramming, conveying, and moving roof supports. During phase II of the project, two dust sources were evaluated: clearance ring cutters cutting in six-inch web width increments, and loading operations. Investigation Results As a result of dust measurements, the gage cutters were determined to be the major dust-generating source on the shearer. These cutters, at 6-inch web depth, produce three times as much dust per unit volume as is produced at 30 inches full web depth. The following list of averaged values for the mines tested shows that shearer cutting generated averaged dust levels four times as high as those generated by conveying, and approximately five times as high as those generated in moving roof supports.

Jan 1, 1984

By Oleg Terichow

Electrophoretic mobility measurements were made by the Bureau of Mines on samples of a Florida phosphate slime to determine the optimum conditions of coagulation and settling in an aluminum sulfate solution. Addition of anthracite to promote mutual coagulation demonstrated the practicability of heterocoagulation by reduction of the repulsive effect of double layers. By proper selection of the electrolyte and its concentration, the reduction of the double layers to a net zero point of charge causes the predominance of Van der Waals' forces of attraction leading to the coagulation and rapid settling of both particle systems, as is predicted by the Derjaguin-Landau-Verwey-Overbeek theory of colloidal stability. Confirmation was found in the microfiltration tests where a modified Carman equation was applied to evaluate the specific filter bed resistance.

Jan 1, 1975

By W. S. Sanner

A High Splint coal was carbonized in a low-temperature, fluidized-bed sys-tem to study the effects of thermal cracking on the products of decomposition. The coal was fluidized in recycle gas at 485° to 600° C, and the products were cracked at 600°, 700°, and 800° C in a bed of fluidized coke. Yields of tar, pitch, paraffins, and olefins decreased as carbonization temperature increased. Thermal cracking of the tar vapors produced the highest tar yields at 600° C, and light oil yield increased at cracking temperatures up to 700° C. At an 800° C cracking temperature, the yield of light oil decreased.

Jan 1, 1969

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

Reduce or prevent acid mine drainage from coal refuse piles and surface mines by inhibiting the growth of acid-causing bacteria. Approach A dilute surfactant or deter? gent solution is applied directly to coal refuse piles or overburden using a hydro-seeder or road watering truck. The surfactant treatment can be used either as a preventive measure to avoid a potential acid drainage problem or to reduce water treatment costs by controlling acid drainage at its source. How It Works Acid drainage is prevented or reduced by inhibiting the growth of Thiobacillus ferrooxidans, a type of bacteria which obtains most of the energy it needs to survive by oxidizing ferrous iron in water. The oxidized iron in turn attacks pyrite, which forms an acid and additional ferrous iron for the bacteria to oxidize. T. ferrooxidans is protected by an outer membrane which enables it to survive in its acid environment. Anionic surfactants, or surfactants containing negatively charged ions, can be used to destroy this membrane, thus killing the bacteria and slowing down the oxidation of acid-forming pyrite. Of the anionic surfactants tested to date, sodium lauryl sulfate (SLS) appears to be the most effective as a bactericide. Alpha olefin sulfonate and alkyl benzene sulfonate are acceptable alternatives. These surfactants are major components of common household products, such as laundry detergent, shampoo and toothpaste. They are, therefore, readily available, inexpensive, biodegradable and present no environmental problems at low concentrations.

Jan 1, 1983

By Lewis C. Karrick

In studying the destructive distillation or pyrolysis of oil shales, the primary consideration is to determine the effects of heat on the organic components of the shale. The impracticability of separating these organic components, collectively known as "kerogen", from the mineral matter with which they are associated renders the problem extremely complex. The behavior of the kerogan in the shale while undergoing the heating process is probably different from that of the same kerogen if it could be isolated and treated under similar temperature conditions, and in fact the results of actual distillations have shown that the physical properties of the mineral matter in the shale may be the cause of much variation in the products of retorting. It must be remembered that the inorganic .material of the shale is a heterogeneous mixture of minerals solidified into a very close-grained compact mass. This mineral mass has a thermal conductivity different from that of the kerogen, thus complicating the problem of even distribution of heat. Furthermore, the temperatures of dehydration of gypsum end some; hydrous silicates are included within the temperature range of the shale distillation, These minerals are frequently present in the shales; and the evolution of water vapors from them will affect the partial pressures of the hydrocarbon vapors evolved from the kerogen, probably tending toward, the improvement of the quality of the oil distillates. Carbonates and sulphides which are also frequently present begin to decompose within this range of temperature, and the gases produced from them may alter the chemical constitution of the oils produced from the kerogen.

Jan 1, 1922

By A. W. Kbair, L. D. Gehl

"INTRODUCTION The rock-bit interaction during the cutting process in underground mines has been a matter of great concern to mining operators, researchers and manufacturers, particularly after the passage of strict environmental laws. Coal cutting bears directly on airborne coal dust generation and rock cutting generates frictional sparks which may cause face ignitions, jeopardizing the productivity, safety and economy of the industry. It is imperative to investigate into the factors which have influence on bit we.ar. Hurt and Evans (1981) concluded that the point attack bits have greater ignition potential than the conventional wedge shaped bits, and also worn bits were more responsible for ignition than the new bits. The results of a study (Khair et al., 1992) suggested that after 7% weight loss, the bit should be replaced. The polycrystalline compact diamond (PDC) tipped bits are reported to be cost effective in a study done by USBM (Twin Cities Research Center), and it was stated that the PDC tipped drill bits had 80 to 100 times longer life than the ordinary tungsten carbide (WC) tipped bits.This paper presents the results of the experiments which were conducted utilizing a coal cutting simulator at the laboratory of the Department of Mining Engineering, West Virginia University, USA. The description of the machine and the experimental set-up have been described elsewhere (Khair et al., 1989; Gehi & Khair, 1994), and therefore, will not be discussed here. The rock types which were used in experimen~ are Tennessee sandstone, Berea sandstone and Indiana limestone. The operating parameters include (1) drum speed, (2) water spray pressure and (3) bit type. Besides studying the wear characteristics influenced by the above mentioned variables, the effect of these parameters on the required cutting force, specific energy consumption, acoustic emissions rate and rise in temperature of the bit were also studied. A preliminary study was also done to compare we.ar characteristics of the WC bits with those of the poly-crystalline compact diamond tipped bits."

Dec 1, 1995

By J. A. Organiscak

Two types of airflow splitting methods for improving longwall dust control were investigated by NIOSH's Pittsburgh Research Laboratory. These methods included a translucent mesh barrier and a staged spray barrier system to confine the shearer-generated dust to the coal extraction side of the longwall face while maintaining a cleaner split of airflow on the opposing worker walkway side of the longwall face. The translucent mesh barrier was shown to provide notable dust control effectiveness up to 60 m downstream of the shearer in both the laboratory experiments and a longwall field evaluation, provided the mesh barrier remains relatively parallel to the airflow. The staged spray barrier system showed marginal dust control effectiveness in the laboratory and subsequently was not field tested.

Provide a means to (1) rapidly disconnect a multifunctioning signal channel from a multichannel data collection system, (2) protect electronic devices from damage while causing the minimum amount of data collection disruption, and (3) operate electronic devices under gassy mine conditions. Background Data collection system instrumentation and cables are often located in hazardous areas of underground coal mines. As a result, frequent damage to the instrumentation cables occurs from roof falls, heavy equipment, and the relocation of air, water, and power lines. A similar problem exists in surface areas where cables and instrumentation can be damaged by animals and by vehicle traffic. Without a circuit-breaking feature, the damaged cables could cause instrumentation to be ruined, cause power supply failure, and otherwise disrupt data collection in some situations the lack of a circuit-breaking feature might cause an ignition in a methane atmosphere.

Jan 1, 1990

By A. L. Engel

The sample of ore on which the work described in this paper was done came from Mina Oriente, Carrizal Bajo, Provincia de Atacama, Chile, South America, and was sent at the request of the Chil.ean Government through the Foreign Minerals Division of the Bureau of Mines. This ore had been tested locally for treatment by flotation and cyanidation without satisfactory results. An additional difficulty was the absence of water near the ore deposits, so that in any treatment method considered the water requirements would have to be very low. It was desired to develop a practical method of recovering the gold and, if possible, the copper in the area. No data of previous investigations were made available. The sample received was mostly quartz, highly brecciated, with limonite and hematite in the fractures. Copper occurred as malachite and azurite, also in the fracture s and to a slight extent as a stain in the quartz. Some fine-grained pyrite with a little arsenopyrite occurred within the quartz. An occasional grain of chalcopyrite was observed. No free gold was seen during examinations of the ore, but amalgamation indicated that some was present.

Jan 1, 1949

By G. R. Friggens

A nuclear method for continuously monitoring the coalbed and ash levels and void formation in commercial-scale, fixed-bed, pressurized gas producers is proposed. Measurement of gamma ray transmission through the coalbed is the basis of the method. The coalbed level is monitored by detecting the trans-mission of gamma rays from a 1 to 2 Ci Co-60 source positioned on the outside wall of the vessel. Coal bridging or, alternatively, ash level is monitored by a 10 Ci Co-60 source at the center of the coalbed. Source activities and geometries are calculated for a 12-foot-ID producer designed to operate at 350 psi. Source capsule and detector specifications and operational safety are also discussed.

Jan 1, 1973

By Fred N. Kissell

In this report the importance of diffusion in controlling the emission of methane in mines is examined. An in-situ diffusion parameter is defined and calculated for a hypothetical unfractured lump of coal in the Pittsburgh and Pocahontas No. 3 coalbeds. The values obtained are similar to those obtained with lump coal in laboratory experiments.

Jan 1, 1972

By H. H. Fukubayashi

This Bureau of Mines report describes the development of a pyrometallurgical process for the recovery of the zinc and lead contained in brass smelter flue dusts, which constitute a recycling or disposal problem. Tests on brass flue dust from several sources were made in a quartz tube, heated by an electric furnace to temperatures as high as 1,050° C. The dusts were mixed with carbon and heated in an oxygen-free atmosphere. It was demonstrated that 98 pct of the zinc and 12 to 25 pct of the lead, both in the metallic state, could readily be removed from the dusts. It was also found that 75 pct of the zinc could be recovered, with less than 0.1 pct of the lead, in the absence of chlorides. Pelletization techniques were investigated and 0.6 inch pellets were found to be optimal. Pelletizing results in a tenfold reduction in volume.

Jan 1, 1974

By T. F. Tomb

This paper describes field and laboratory investigations conducted on a dust-collection system recently designed for integral use with a continuous mining machine. The results of the field study showed that the average respirable dust concentration measured at the machine operator's position was reduced by about 60 percent (from 8.7 to 3.5 milligrams per cubic meter), and total and respirable dust concentrations in the return air were reduced by approximately 70 percent. The data indicated that approximately 20 percent of the dust generated at the face was not passed through the scrubber. The lab-oratory results showed that the overall efficiency (by particle count) was approximately 80 percent for total dust concentrations (minus 20 micrometers in size) typical of those encountered underground. Calculations based on total dust concentrations measured during the underground study indicated that the respirable mass concentrations of the effluent from the scrubber would still exceed acceptable levels even if scrubbing of all the air at the face were possible.

Jan 1, 1973

By Fred N. Kissell

Methane flows and pressures were measured in mines in the Pittsburgh, Hartshorne, and Pocahontas No. 3 coalbeds. From the data, the permeability of each of these coalbeds was computed. It was found to depend strongly on the type of coal and on the amount of water in the coalbed, and it was found to increase with time. All of the coalbeds had a high-permeability zone adjacent to the face or rib, and the Pittsburgh bed exhibited directional anisotropy. Surprisingly, little or no overburden effect was observed.

Jan 1, 1972

Develop design and support guidelines for coal mine entry intersections based upon results of integrated field and numerical modeling analyses of structural parameters for improving ground stability. Background Underground coal mines contain a large number of entry intersections. Dome-shaped zones over the intersections are unstable and are often associated with roof falls. These roof falls may occur during mine development, trapping equipment and endangering miners. These high-risk areas of the mine account for 10 pct of the total number of ground-failure-caused fatalities. The falls, ranging from heights of 1 to 20 ft, cause high dilution and slow the advance rates. Stability at intersections is influenced by four structurally interrelated parameters: in situ stress, geological discontinuities and physical properties, intersection geometry, and roof span. Because of the complex interaction of these parameters, the actual mechanism of roof failure may vary considerably, depending upon the roof lithology, rock strength, and stress conditions.

Jan 1, 1990

By L. C. IlsLey

The first thing to consider in prevention of electric shock is the voltage of the circuit. No person can be sure that he will not be killed, even from a 110-volt circuit, if he makes proper contact with the circuit so as to cause the maximum current to pass through his body. As the voltage is increased to 250 volts, 500 volts, or 2,300 volts the danger from contact with the electric circuit is increased, Alternating current of the same nominal voltage is possibly more dangerous than direct current. Experience has taught us that both will cause death, and that if the fatalities from this source are to be kept low, certain precautions in the guarding of circuits must be observed.

Feb 1, 1929

By G. G. Morgis, J. J. Forbes

"INTRODUCTION The greatly diversified and increased uses of beryllium and its con& pounds in recent years have focused attention on the health hazards incident thereto. The Bureau of Mines has a fundamental interest in safety and the elimination or reduction of health hazards in the mineral and allied industries, and it recognizes that serious hazards are inherent in the production and use of beryllium and its compounds. This circular presents a review of the literature pertaining to such health hazards but does not describe original research by Bureau personnel. Most of the bibliography has boon either quoted in part or abstracted in an effort to present information in a comprehensive and readable form.In reviewing the literature, differences of opinions wore recognized in the writings of the respective authors, but no attempt was made to evaluate such differences. This presentation was devoted strictly to reporting without editorial comment.SUMMARYAlthough beryllium was known to industry for about 150 years, its toxicity did not present any serious problems in the United States until the advent of World War II, when the increased use of this element and its compounds brought to light several toxicologic reactions occurring primarily in the lungs and skin of workers handling it. The pulmonary effects, characterized as acute pnoumonitis and chronic pulmonary granulomatosis in beryllium workers, are far more serious than the dermatological manifestations.The addition of beryllium to the list of toxic industrial metals has boon so recent that there is still some confusion in the clinical picture. Data on magnitudes of exposure likely to be responsible for the production of disease are not yet adequate. There appears to be no relation between the severity of exposure and the development of cases some of those having had severe exposure have not developed a reaction, whereas those having a slight exposure in some instances have developed a response."

Jul 1, 1950