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Improve safety at mineral operations that use cyanide leach solutions to recover precious metals from finely ground ores, Approach Provide an alternative, non-acidic means of cleaning processing systems such as the State-of-Maine filter system, thereby reducing the exposure of workers to toxic hydrogen cyanide gas (HCN), The Problem Many gold and silver mining operations use cyanide solutions to dissolve gold and silver from ores. The precious metals frequently are recovered from pregnant leach solutions by the Merrill-Crowe recovery process, whereby gold and silver is precipitated with zinc dust. When that method is used, suspended particles in the leach solution must be filtered out before zinc precipitation can occur. This filtering is accomplished with small packaged plants, such as the State-of-Maine (SOM) filtering system. Unfortunately, the filters become clogged with calcium carbonate scale after about 2 to 10 days of operation and must be cleaned before further precious metals recovery operations can continue, Cleaning the system is a hazardous task because the acid is not compatible with the alkaline cyanide leach solutions, and toxic hydrogen cyanide (HCN) gas may be produced when the acid and solution are mixed. That gas, if breathed or contacted with the skin, can cause cyanosis which may induce nausea and even asphyxia and death. To reduce this danger, the Bureau of Mines has devised a safer method of cleaning clogged filters,

Jan 1, 1986

By B. Dimitriades

Exploration of the photochemical reactivity of diesel-exhaust hydro-carbons is described. A smog chamber was built, and reactivities of diesel exhaust, gasoline exhaust, and propylene were measured at two chamber temperatures. Experimental data indicated the problems caused by instability of diesel-exhaust hydrocarbons. With reservations due to these problems, the results are interpreted to reflect comparable reactivities for diesel and gasoline exhaust.

Jan 1, 1971

Provide a means through which members of the mining community can easily and readily access information on human factors/ergonomics as it relates to mining. Approach As part of a research study aimed at reducing human error accidents in mining the Bureau of Mines developed a computerized information retrieval system which provides relevant human factors or ergonomics information on 19 mining-related special interest categories.

Jan 1, 1988

By J. W. Paul, A. C. Fieldner

"In cooperation with the New York and New Jersey State Bridge and Tunnel Commissions, the Bureau of Mines has just completed the construction of an experimental tunnel in the Bureau's experimental mine at Bruceton, Pa., near Pittsburgh, Pa. The purpose of this tunnel is to make a final study of the ventilation problems arising in the adequate ventilation of vehicular tunnels for automobiles and trucks, especially the 9000-foot tubes that are being designed. to handle the traffic between New York City and New Jersey under the Hudson River.Chief engineer, Clifford M. Holland, of the Tunnel Commissions has shown that there are three principal problems involved in planning the ventilation of this tunnel, namely - (1) The amount and composition of exhaust gases from motor vehicles; (2) The dilution necessary to render these exhaust gases harmless; (3) Determination of coefficients of airflow and horse-power required in ducts, bends and openings.Composition of automobile exhaust gases.The answer to the first problem was obtained by making road tests on 101 automobiles and trucks at the Pittsburgh experiment station. These machines were taken from service without any previous adjustment so that the composition and amount of the exhaust gas may be taken as representative of actual operating conditions prevailing in the tunnel. A report covering the results of these tests was submitted to the chief engineer of the Tunnel Commissions, on November 1, 1920, and 411 be published in the report of the commissions. Several papers a have also been published in the technical journals summarizing the important results as regards tunnel ventilation and also with reference to gasoline losses in present-day motor car operation due to the general use of unnecessarily rich mixtures"

Oct 1, 1921

By J. E. Matta

The Bureau of Mines has developed a tracer gas method for measuring leak-age through permanent mine stoppings. In this method, a temporary brattice is erected in the same entry as the leaking permanent stopping. Leakage was evaluated from concentration measurements of a tracer gas introduced into the space between the stopping and brattice. Stopping leakages ranging from 15 cfm to 265 cfm were simulated in an underground coal mine. Leakage values determined by the new method were within 10 pct of the known values.

Jan 1, 1978

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 Michael J. Griffin

Science involves the study of the nature and behaviour of natural things and the knowledge we obtain about them. Scientific endeavour leads to the unfolding of new knowledge and adjustments to our understanding and our behavior. To indicate that we ‘know’ something may merely mean we do not feel able to, or that we do not wish to, disagree with others who claim to know; or it may mean we have either heard about it, or studied it, or understand part of it, or accept that it is true, or have seen evidence to be convinced of its veracity. What do we ‘know’ about the health effects of vibration? There are many unknowns in the field of human responses to vibration. Not all would agree on what is known and what is unknown. This paper seeks to summarize what we know that we know, what it is sometimes claimed that we know, and what we know that we do not know about the relation between exposures to vibration and our health. It also speculates on what we do not know that we do not know. Hand-transmitted vibration What we know we know We know that exposures to hand-transmitted vibration result in various disorders of the hand, including abnormal vascular and neurological function. Not all frequencies, or magnitudes, or durations, of hand-transmitted vibration cause the same effects. What we may claim to know To enable exposures to be reported and compared, they are ‘measured’ and ‘evaluated’ using defined (e.g. standardised) procedures. This involves identifying what is to be measured and specifying how it is expressed by one (or a few) numbers. Summarising a vibration exposure in a single value involves assuming the relative importance of components within the vibration (e.g. different magnitudes, frequencies, directions, and durations), so standards define ‘weightings’ for these variables. The importance of the weighted values may also be suggested, allowing ‘assessments’ according to a criterion (e.g. the probability of a specific severity of a specific disease). Standards for the measurement and evaluation of hand-transmitted vibration define a frequency weighting and time dependencies that allow the severity of vibration exposures to be assessed and the probability of finger blanching to be predicted 1. What we do not know We do not know that the frequency weighting in current standards reflects the relative importance of different frequencies and axes of vibration in producing any specific disorder. We do not know whether the energy-based daily time-dependency inherent in A(8) reflects the relative importance of vibration magnitude and daily exposure duration. Consequently, the relation between A(8) and the years of exposure to develop finger blanching, as in an appendix to ISO 5349-1 (2001), is not well-founded. We do not know, or at least there is no consensus on, the full extent of the disorders caused by hand-transmitted vibration (e.g. vascular, neurological, muscular, articular, central), or the pathogenesis of any specific disorder caused by hand-transmitted vibration, or the roles of other factors (e.g. ergonomic factors, environmental factors, or individual factors). We know that acute

Jan 6, 2006

To produce industrial-grade titanium castings by processes that are nonpolluting and lower cost than the currently used rammed-graphite process. Approach Foundry-grade zircon and olivine sands, bonded by waterglass or bentonite, are used to make shell or rammed molds which require relatively low-drying temperatures and do not generate noxious fumes during drying or casting. Procedures Three separate processes have been developed which meet the stated pollution and cost goals. These are: 1. Waterglass-bonded rammed zircon or olivine sand molds are dried at 480°F, zirconia washed, redried, and used in an inductoslag or skull-casting furnace. 2. Waterglass-bonded zircon or olivine sand shell molds are formed at 560°F, cured at 620°F, zirconia washed, dried at 480°F. and used in an inductoslag furnace. 3. Rammed zircon and olivine sand molds are bonded with western bentonite, zirconia washed, dried at 980°F, and used in an inductoslag or skull-casting furnace.

Jan 1, 1981

By N. S. Dalal, W. Irr, X. Shi, V. Vallyathan

"Inhalation of crystalline silica is associated with a biphasic biologic response of acute cell injury and chronic pulmonary fibrosis. Dust induced cell membrane injury leading to the release of lysosomal enzymes and cell death has been implicated as the initial important biologic event triggering the fibrosis. However, it ls also possible other biologic reactions could alternatively, or in addition to these enzyme related cytotoxicity reactions, alter the normal functioning of cells. It is well known that phagocytic activation results in the production of oxygen radicals which are highly cytotoxic to cells. In healthy - lung, protection against the toxic effects of the normal balanced ·biologic reactions are provided by a number of defen1e systems including antioxidants. In disease or condition of overproduction of oxygen radicals, biochemical protection may be overwhelmed with resultant cellular injury.Our recent observations have shown that reactive oxygen radicals (ROR) are generated during grinding of crystalline silica. We hypothesized that these newly generated RORs may cause cell injury, lipid peroxidation, or even damage to macromolecules such as DHA. Biochemical aberrations caused by the inhalation of crystalline silica with ROR at occupational settings might overwhelm cellular and antioxidant defense systems of the lung leading to injury and subsequent fibrosis.To test this hypothesis, we have investigated the generation and decay of ROR produced by crystalline silica using electron spin resonance (ESR) and investigated its toxicity with conventional biologic tests at various time intervals after grinding. We also studied the decay of these newly generated RORs in buffer and the effect of antioxidants and scavengers in the abolition of cellular damages."

Jan 1, 1989

To rapidly and dependably locate shorts and opens in mining equipment power cables. Approach: The approximate locations of faults are found using a sound pulse echo, then the faults are exactly located with one of two probes. How It Works: To approximately locate u fault in shielded or unshielded cable, the cable is disconnected from the mine power center, and connected to the sound pulse generator. The generator is also connected to the ground conductor of the cable. When the generator is energized, electrical pulses are transmitted, and each moves along the conductor until it reaches a fault. When a pulse reaches the fault an echo returns to the instrument, either a positive pulse if the fault is an open, or a negative pulse if the fault is a short. See Figure 1. The further along the cable the first fault is from the instrument, the longer it takes for the echo to return. The instrument automatically measures the time and calculates the distance. The distance in feet is shown on an illuminated digital display.

Jan 1, 1976

To minimize support costs and to improve ground control by improving wood-crib design and utilization through the development of engineering methods that will match the placement and performance of the wood cribs to the load conditions imposed by the mine environment. Background While wood cribs are used extensively to stabilize mine openings, their utilization is often based on historical practice or trial-and-error rather than on engineering design. This has led to conservative crib utilization where more capacity than is necessary is employed or inadequate capacity is provided when mine conditions worsen. Critical design parameters, such as the stiffness of the support structure, are often ignored. Optimum crib design and employment is becoming increasingly important as the utilization of wood cribs increase due to the growth of longwall mining, and as the cost of wood continues to rise. A single longwall operation will spend as much as a million dollars per year on the support of the gate roads.

Jan 1, 1994

Increase the safety of underground mine workers by minimizing hazards associated with rerailing mine cars after derailment. Background and Approach A serious operational problem in underground mines is the task of rerailing mine cars. Current rerailing practices are not only hazardous but are inefficient as well. Most methods involve pulling the derailed car back onto the track with a locomotive. This causes damage to the road bed and is not effective on curves or in situations where the car's wheels are too far from the rails. Jacks, wooden props, and pry bars are also used to raise or lower cars back onto their tracks but methods involving these tools require much strenous manual effort by mine workers, thus posing possible serious injuries. The problem is further compounded by the cramped, narrow confines of the underground mine environment which allows no space to permit use of cranes or other surface railroad rerailing techniques. The Bureau of Mines, aware of these problems, investigated improvements in current underground rerailing methods. Through a cooperative effort with Hoesch MFD, a system was designed and modified that can be easily carried into the mine by workers and quickly assembled at the derailment site. The system is hydraulically and pneumatically powered rather than reliant upon manual operation.

Jan 1, 1986

By Lynn L. Rethi, Barbara Fotta

Recent employment figures (taken from the Mine Safety and Health Administration's database) indicate that the number of independent contractor' employees working in the coal mining industry has doubled over the past ten years. As their numbers increase, they become a more visible segment of the industry. [ ] Increased exposure to mining hazards has also brought an increase in the number of fatalities involving independent contractor workers. One gauge that is traditionally used to evaluate the overall safety of an entity is the "number of fatalities." Over the five-year period from 1985-89, 27 independent contractor employees were fatally injured while working on coal mine property. This number increased to 45 fatalities during the subsequent five-year period from 1990-94. Nearly half of these fatalities (47%) were due to accidents involving powered haulage (See Table); 13% were electrical accidents; and 9% were machinery accidents. Combined, these three accident classifications accounted for 69% of all coal nine independent contractor fatalities. Information taken from fatality data is an important piece of the safety puzzle; however, other variables need to he examined in order to better define contributing factors associated with accidents. More specifically, information on trends in fatal and nonfatal accident and injury data is necessary before deciding what approach should be used to improve safety. In order to implement appropriate safety strategies, it is important for safety practitioners to examine all available lost time accident and injury information. The following coal industry data sites specific and present trends of independent contractor employees working in underground locations at coal mines, surface areas of underground coal mines, surface coal mines, and preparation plants. The data compares employment and accidents for time periods at the beginning and the end of a ten-year span from 1985 to 1994. Because the number of incidents involving independent contractors in certain accident categories during any one year may be small, three-year totals are used; the first three years (1985-87) of the ten-year period are compared with the last three years (1992-94). [ ]

Provide reasonably priced, reliable fire protection for blasthole drills. Approach An automatic fire sensing and suppression system using both dry and gaseous chemicals was developed, and is more shock and vibration resistant than similar industrial fire protection systems. How It Works Temperature sensors mounted in the drill's machinery house, hydraulic room, operator cab, and transformer area detect the heat from a fire, and trigger a sequence of actions. The same fire fighting sequence can be initiated from manual alarm boxes in the cab, hydraulic room, or machinery house. Electrical power to the drill Is immediately cut off, and a horn sounds to warn the drilling crew. After a 40-second, built-in, delay to allow time for drill's ventilating fan to stop, gaseous and dry chemical fire extinguishing agents are piped to and released in various rooms of the drill. The gaseous extinguishing agent (Halon 1301) is released in the machinery house, hydraulic room, and operator cab where dry chemical clean-up from electrical panels and machinery would be difficult and costly. Dry chemical is piped to the transformer room at the rear of the machine. Location of the principal components of the system are shown in the drawing.

Jan 1, 1979

By Richard E. Hucko

The bureau of Mines conducted a laboratory scale investigation of the process of selective flocculation with the objective of developing a method to effect separations on suspensions consisting predominately of ultra-fine-size (minus 400-mesh) particles of coal and refuse. Selective flocculation of coal from coal-refuse slurries could be achieved with a wide variety of reagents. Typically as much as 15 to 20 weight-percent of high-ash solids (70 to 80 percent ash) could be retained in suspension. The flocculated sediment remained a high-ash product, however, and would require further treatment to be regarded as clean coal. No combination of reagents and conditions led to selective flocculation of the refuse component. The dispersing agent was found to be the critical factor; dosages of 3 to 8 lb/ton2 were necessary to stabilize the suspension for subsequent selective flocculation. In addition, most of the dispersants that worked were most effective at substantially elevated pH (11 or so). It was concluded that this process would be prohibitively expensive and, because of yield and quality constraints, it would be of questionable utility in today's coal preparation industry.

Jan 1, 1977

Mine closing methods should be carefully considered. If not properly sealed, an abandoned mine may continue to produce acid water. Since 60 to 90 percent of the total acid discharged from all coal mines is from abandoned mines,(58) some states require that provisions for sealing be contained in the mining permit application. Closing an operation to prevent harmful mine drainage into nearby runs and streams is a subject of much concern to states as a result of continuing problems from long abandoned mines which were improperly closed.

Jan 1, 1970

By A. D. Mah

Thermodynamic data on compounds of arsenic and sulfur were critically evaluated by the Bureau of Mines. Changes of standard enthalpy and Gibbs energy, and logarithms of the equilibrium constants were tabulated as a function of temperature for reactions involving these compounds.

Jan 1, 1982

By George J. Conroy

Techniques for locating trailing-cable faults are discussed, particularly those techniques suitable for use in underground coal mines, which have been the subjects of Bureau of Mines research. The discussion concerns precautions and suggestions for locating faults, rather than detailed descriptions of apparatus.

Jan 1, 1979

By John C. Edwards, Fred N. Kissell

Experimental work by the Bureau of Mines indicates that when a coalbed is degassed by boreholes, the flow of methane may actually increase with time. This phenomenon appears to be the result of a relative-permeability effect; that is, the coalbed permeability to the gas increases sharply with decreasing water saturation. This report reviews the background of experimental evidence indicating a relative-permeability effect, and presents the results of a computer simulation of two-phase flow in coal.

Jan 1, 1975

By W. K. Overbey

Knowledge of fracture systems in oil or gas reservoirs is essential to the efficiency of both primary and secondary production operations. A relationship was established between structural features of the surface and both natural and induced fractures in oil and gas reservoirs, thus providing a method of predicting the direction of rock fracture prior to field development and well completion. Correlations between the surface features and under-ground fractures resulted from analysis of joint strike measurements, bottom-hole impression packer surveys, photographs of hydraulically fractured wells, fracture data from oriented cores, in situ strain measurements from formation outcrops, and lineament analyses from aerial photographs. The mean orientation of surface fractures, lineaments, and stress field directions ranged from N 53° E to N 73° E, compared with an average orientation of N 63° E for the hydraulically induced fractures. Tectonic stress field was shown to influence the direction of hydraulically induced fractures. This report presents the details and application of techniques to obtain the orientation of the principal horizontal compressive stress field component and thus the direction of induced fractures.

Jan 1, 1971