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By J. N. Tomlinson

Trailing-cable splices are evaluated for moisture exclusion abilities after repeated travel over shuttle-car sheave wheels. Tests are conducted on cables with jackets made of neoprene, cholrosulphonated polyethylene (CSPE), and nitrile butadiene-polyvinyl chloride (NBR-PVC) to 50° C. The results show that some splice kits are effective as received, others are improved with minor but significant changes, and still others must be redesigned to be effective in underground applications. Laboratory results are compared with actual underground splice results. Recommendations for cable preparation prior to splicing are presented.

Jan 1, 1979

By Forrest T. Moyer

THIS CHAPTER of the Minerals Yearbook contains injury experience and related employment information for the coal-mining, coking, oil and gas, peat, and native asphalt industries in the United States for 1962. Injury experience is measured by the number of injuries sustained per million man-hours of exposure in each industry. No attempt has been made to combine these data and present rates reflecting the mineral-fuel industries because the hazards of the separate industries are not comparable. Tabulations showing the trend of injuries and employment for all mineral industries are presented in volume III of the Minerals Yearbook. COAL The injury-frequency rate for the coal-mining industry of the United States increased less than 2 percent, according to reports received by the Bureau of Mines. The number of fatal and nonfatal injuries per million man-hours in 1962 was 45.86, based on final data for anthracite mines and preliminary data for bituminous coal and lignite mines.

Jan 1, 1963

Reduce the dust levels to which jacksetters and helpers on auger mining sections are exposed by identifying viable, effective methods for control-ling respirable dust on these sections. Approach The Bureau of Mines con-ducted laboratory tests and respirable dust surveys to identify the factors that distinguish clean auger mining operations from dusty ones. Study Results Results of the Bureau's study revealed that ventilation is the most important element of auger mining dust control. The four must important venitilation parameters are airflow, curtain configuration, curtain setback, and curtain installation.

Jan 1, 1988

By Fred N. Kissell, J. E. Matta, J. C. LaScola

The Bureau of Mines made laboratory absorption measurements on oil shale samples, which showed that the amount of methane absorbed is proportional to pressure and oil yield, and can be much larger than would be predicted based solely on porosity. Oil shale cores collected in the field were also measured for their gas content using the Bureau of Mines direct method, Cores taken from deep locations and far from outcrops yielded more gas than cores from shallower locations or at outcrops, when taking into account variations in oil yield, and all data indicate that oil shale mines that are both deep and far from an out- crop will emit low levels of methane gas.

Jan 1, 1977

By Louis D. Dornetto

The effects of electric shocks on man are an important factor in the design of power systems and protective devices. The current levels just below let-go and just prior to the onset of ventricular fibrillation must be known and taken into consideration in the design of power systems and protective devices. Isolated (ungrounded) electrical distribution systems are compared with resistance and solidly grounded systems. The advantages and disadvantages of each are discussed and recommendations are made. Transients on coal mine power systems are a problem that, until recently, have been ignored. Transient voltage levels that can be expected on both the high and low side of the load center and the effects of transients on electronic equipment and personnel are covered.

Jan 1, 1975

By Peter L. Swanson

NIOSH has developed an automated PC-based seismic monitoring system for use in mine ground control studies. The distribution and coordination of data acquisition and processing functions across a local area network (LAN) is a central feature of the system. Design requirements include (1) the use of lowcost, off-the-shelf, data acquisition and computer hardware, (2) the capability of automatically merging waveform data sets from different types of monitoring systems, (3) delivery of raw and processed data underground and on the surface, as well as to remote sites, and (4) automated data collection and processing over long periods of time without the need for human intervention. Current mine-wide installations utilize multiple, autonomous seismic networks located both underground and on the surface and provide 20 to 40 stations within a radius of several kilometers. Event locations, magnitude estimates, and other processed data are distributed for display and analysis on network nodes both underground and in the offices of mine engineers and managers. This paper describes the system's hardware and software components, examples of installations in hard-rock and coal mines, and a few observations from western U.S. longwall coal mines.

By James J. Hanslovan

Stresses that damage coal mine trailing cables were investigated to obtain a quantified description of cable-stress locations, magnitudes, and frequency of occurrence. Stresses occurring in operating mining sections were measured and observed. Answers to questions that arose during the underground investigations were pursued under controlled conditions, both in the field and in the laboratory. Cable-handling suggestions that minimize or eliminate the stresses are summarized in the form of recommendations to mine operators.

Jan 1, 1979

Develop a new method for coal mint pillar stability evaluation and design based on pillar load measurements. Approach A novel approach to chain pillar stability evaluation and design for longwall coal mining panels has been developed by the Bureau of Mines. The evaluation approach uses an INTEGRITY FACTOR as the criterion for stability. Hydraulic borehole pressure cells developed by the Bureau are used to measure stresses in a pillar for stability evaluation. The results are used to improve the pillar design.

Jan 1, 1989

Provide a method of detecting and locating miners trapped underground following a mine disaster. Approach Develop a surface deployed system which senses the vibrations caused by a trapped miner pounding on the roof of the mine and effectively determines the miner's location. How It Works If trapped underground, a miner would strike the roof of the mine with any implement at his disposal. This pounding causes vibrations in the ground which are transmitted to the surface where they are sensed by receiving transducers called geophones. Multiple geophones are positioned together for noise cancellation purposes in a form called a subarray. Seven

Jan 1, 1981

By James C. Cawley

A summary is presented of existing leaky feeder communications systems currently in operation in North America. Background information pertaining to previous use of leaky feeder technology is discussed along with the survey methodology. A review of some pertinent facts concerning propagation in tunnels and specific reference to mine tunnel propagation is presented. A summary of the characteristics of each mine visited is presented in tabular form, and methods of procurement and maintenance are discussed. The role of user training in efficient system use is presented. Seven sites representing eight mines are included in the survey. Economic and technical topics are considered.

Provide a central source of subsidence reference in formation for industry, academia, and government agencies interested in improving subsidence prediction and analysis under U.S. mining conditions. Approach Develop a comprehensive bibliography about mining related surface subsidence and store this information in a computer file. Make specific references accessible through a key word retrieval program. Supplement these key word identifiers by entry of author's name, title of publication, subject of text, or sponsor of publication. How It Works Requests for subsidence in-formation are made by phone or mail to the Bureau of

Jan 1, 1982

By John D. Corrick

Three species of chemosynthetic iron- and sulfur-oxidizing autotrophic bacteria have been isolated from the leaching waters of copper mining areas. These species are: The sulfur-oxidizing Thiobacillus concretivorus, the iron-oxidizing Ferrobacillus ferrooxidans, and a sulfur- and iron-oxidizing bacterium closely resembling Thiobacillus ferrooxidans, INTRODUCTION Among several suggested new processes for treating marginal ores in the United States, none is more intriguing than the possibility of extracting metals from low-grade materials by the action of microorganisms One phase of a Federal Bureau of Mines investigation toward developing such a procedure was to isolate and identify specific chemosynthetic iron and sulfur. oxidizing autotrophic bacteria native to certain domestic copper deposits where leaching is practiced. The bacteria or microorganisms considered important to this investigation are those capable of producing solutions of ferric sulfate and sulfuric acid. Solutions of this type are excellent solvents for some copper minerals By establishing the presence of these bacteria at certain copper-leaching areas, strength would be given to a theory that microbial activity is partly responsible for the oxidation that takes place at these areas. Their presence also advances possibilities for controlled use of microbial action in metal extraction processes. Leathen4/ has demonstrated that one of the chemosynthetic iron-oxidizing bacteria, Ferrobacillus ferrooxidans, can oxidize 200 parts per million of ferrous iron to the ferric state in 3 days,

Jan 1, 1961

Provide a simple and effective means of measuring mining-induced pressure changes in coal mine roof and pillars. Approach Develop a reliable, easy to fabricate and install borehole instrument which measures mining-induced pressure changes in pillars and in the mine roof. Ground pressures are monitored through use of aluminum platens coupled with d copper flat jack. How It Works The Bureau's instrument measures mining-induced pressure changes by transmitting strata pressure through the aluminum platens to an oil-filled borehole platened flat jack (BPF). Pressure in the flat jack is displayed on a gage located outside of the borehole. The instrument is in-stalled in the borehole by inflating the flat jack using a hand-held hydraulic pump. In addition, the platens have been designed to allow up to three BPFs to be installed in a single borehole, thus permitting pressure change measurements in more than one direction from a single borehole. Installation pressure is calculated on the basis of the estimated pressure exerted by the overburden and the percent of recovery after intial mining has

Jan 1, 1986

To improve mining safety and efficiency by providing a practical way of detecting faults and channel sands that disturb coal seams. Approach A seismic system using a shallow blasthole has been developed and tested. How It Works A small shock is caused in a shallow hole, sending seismic waves through the ground. These waves are reflected from the top of the coal seam, acid are detected by a line of geophones on the earth's surface. Dampening of the seismic signals by channel sands and other discontinuities in the seam is detected and recorded. See Figure 1. The seismic shock wave can be produced by exploding small charges, dropping a weight, firing a gas gun, or actuating a vibrator. Depending on the soil cover, the shock is usually generated in shallow vertical holes about 10 feet deep. Hole depth depends on the soil mantle thickness because it is preferable that the seismic shock originate below that layer.

Jan 1, 1976

Provide an environmentally compatible means of producing lead from galena concentrates that replaces the current high-temperature pyrometallurgical primary lead smelting process and supplies pure lead metal within present and proposed Environmental Protection Agency (FPA) and Occupational Safety and Health Administration (OSHA) lead emission standards. Approach The U.S. Bureau of Mines developed an energy efficient and pollution-free leach-electrowinning method for use in recovering pure lead metal and byproducts from lead sulfide concentrates.

Jan 1, 1989

By G. E. McElroy

[During the period July, 1923, to April, 1924, we made a large number of careful determinations of the resistance to the passage of air in selected sections of airways in the metal mines of Butte, Mont. The experiments were conducted with the cooperation of the Anaconda Copper Mining Co., Frank D. Cannon, mining engineer of that company, and Fred P. Gaethke, mining engineer of the bureau, assisted in carrying out this work. This paper summarizes the, main group of data obtained in the form of a table, of friction factors, or coefficients of friction that is, values of K in the generally accented formula or air flow of [P = KSV or H = KSV2 ] where, in units customary to mining practice;]

Jan 1, 1925

By E. G. Valdez

The Federal Bureau of Mines, in cooperation with Ford Motor Co., investigated the recovery of polyurethane foam and other assorted plastics from the nonmagnetic reject of automobile shredders. Preliminary studies were con-ducted on a 1957 hulk augmented with additional foam and assorted plastics. The proposed flowsheet developed by the Bureau from the preliminary studies consists of a combination of screening, water classification, and gravity separation. The process was then tested on reject from two shredded 1972 cars. All of the foam and between 52 and 70 pct of the assorted plastics were recovered. The composition of the reclaimed foam concentrates ranged from 46 to 66 pct foam; the concentrates were hydrolyzed in laboratory tests by Ford Motor Co. to produce a reusable liquid mixture of polyether glycol monomers and toluene diamine.

Jan 1, 1975

To improve a miner's chance of survival during an emergency by providing immediately avail-able breathable air and protection from toxic gases until a longer-duration breathing apparatus, stored nearby, can be reached. Approach: A belt-carried apparatus which can provide a closed-circuit atmosphere for ten minutes breathing has been developed under a Bureau of Mines contract. How It Works: Water vapor and carbon dioxide in the user's exhaled breath are removed, and oxygen is supplied, by chemical reactions. When the user exhales into the mouthpiece, water vapor in his breath reacts with potassium superoxide (KO2) stored In the canister to produce oxygen. The other product of this reaction (KOH) reacts with carbon dioxide and removes it from the air. The oxygen-enriched air then flows from the canister into two breathing bags. When user inhales through the mouth, that air is drawn out of the bags, makes a second pass through the chemical-containing canister, and flows into the mouthpiece tube. A nose clip is worn to seal off the nasal passages.

Jan 1, 1975

To reduce the possibility of injury to operators and damage to equipment caused by collision of mining vehicles during coal loading. Approach An energy-absorbing bumper was developed and tested underground on a continuous miner. How It Works The bumper, a long box-like weldment backed by five energy absorbers, is attached to a continuous mining machine by a hinge behind the cab. See Figure 1. When a shuttle car collides with the bumper, or when it is otherwise struck, the energy absorbers are compressed. This absorbs and dissipates part of the kinetic energy of the colliding vehicle, thereby reducing or eliminating its destructive effects. Each energy absorber consists of two chambers separated by a freely-moving piston. One chamber (Figure 2) contains hydraulic fluid. The second chamber contains a gas. When a collision causes the absorber to compress, the hydraulic fluid in the first chamber is forced past a metering pin and through an orifice. The hydraulic fluid then pushes against the piston, compressing the gas in the second chamber.

Jan 1, 1978

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