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By John C. Edwards, Gene F. Friel, John J. Opferman, Robert A. Franks

A series of diesel fuel fire experiments were conducted in the Pittsburgh Research Center's Safety Research Coal Mine (SRCM) to determine products-of-combustion (POC) spread rates along a single entry under zero imposed airflow conditions. Six experiments with an average fire intensity of 330 kW and three experiments with an average fire intensity of 30 kW were conducted in a 1 80 m long entry which had an average 2 m height and 4 m width. POC spread rates were measured by the response time of diffusion type CO detectors, positioned at 30 m intervals, to CO concentrations 5 ppm above ambient. For the 330 kW fires, average POC spread rates of 0.22, 0.13, and 0.06 m/s were determined at 30.60, and 90 m distances from the fire. For the 30 kW fires these average spread rates were reduced to 0.08, 0.04, and 0.04 m/s. The measured maximum roof layer temperature 30 m from two of the 330 kW fire was 30 and 36"C, which is less than the 57°C alarm point of a typical mine thermal sensor. It was determined that smoke detectors can be more effective for mine fire detection than CO detectors. The experimentally determined POC spread rates can be used to provide guidance for specification of sensor spacing to improve early fire detection at zero or very low air flows.

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

3. Application of Proposed Revised Standards 57.11-50 to Mines Surveyed 3.1 Subparagraph (a) 1 "Each mine shall have at least two separate and properly maintained escapeways from each working place to the surface which are so positioned that physical or environmental damage to one will not lessen the effective¬ness of the other, and which meet the requirements of travelways and man hoisting standards These escape¬ways shall reach to within 1000 feet horizontally or 300 feet vertically of each working place " 3. 1. 1 Discussion This section will deal with the 1000 and 300 feet distance requirements, Section 3. 5 will deal with the "environmental damage" provisions. During the course of the mine surveys, it became obvious that one mine's 1000 foot distance was nowhere near equal to another' s --not in the actual distance but in the time required to traverse that distance. This -Ls true for the 300-foot requirement as well. The most obvious example is that one could traverse down a 300-foot raise much faster than climbing up the same distance. The temptation is strong to recommend that the distance requirement be changed to travel times instead. However, this approach would unfortunately lead to a lot of subjective evaluations. Having a time requirement for an entire mine evacuation (Subparagraph 6) is one thing, time requirements and the requisite inspection proce¬dures for each working place are quite another.

Jan 1, 1976

Provide d comprehensive source of up-to-date information about technology for revegetating coal mined lands. Approach A great deal of activity and research in the field of coal mine revegetation has been reported in technical literature, both before and after the passage of Public Law 95-87, the Surface Mining Control and Ruclamation Act of 1977 (SMCRA). This information is widely scattered throughout books, scientific journals, periodicals, Government reports, and other sources, and there has been a need to develop a method of accessing it quickly and efficiently. At the request of the Office of Surface Mining Reclamation and Enforcement which promulgates and enforces regulations implementing the act, the Bureau of Mines has prepared a document that identifies literature relevant to coal mine revegetation. Most of the literature available on this subject has been published during the past 15 years. To tap this reservoir of information, 14 data bases were accessed from DIALOG SDI (Selective Dissemination of Information) Service using three keyword combinations (surface mining and reclamation, strip mining and reclamation, and revegetation). This procedure generated over 7,000 listings. The U.S. Department of Energy's ENERGY data base was selected from the 14 DIALOG bases, both for its large number of listings and for its broad coverage of literature. This data base contains all the unclassified information that passes through the Technical Information Center of the Department of Energy, including reports, journal articles, conferences, patents, books, monographs, theses, and engineering materials relating to energy development.

Jan 1, 1986

To facilitate compliance with title 30 CFR 75.1001-1(b), which requires testing and calibrating of trolley line automatic circuit interrupting devices at intervals not to exceed six months. Approach Calibration of a circuit breaker ideally implies the passage of the expected fault current through the sensing circuit, and observing a successful circuit interruption at the preset level within a specified time. On trolley lines, the required current may be a few thousand amperes, with maximum duration well exceeding one-tenth of a second. Any method of obtaining this calibration current Involving the trolley wire can contribute to wire sagging and other permanent damage to the haul-age system due to the high energy dissipated during the test. Also, control to assure that exactly the required level and duration of current flow is obtained implies the use of equipment which is simply not available In the ordinary mine. Under a Bureau of Mines contract, a circuit to achieve the necessary calibration pulse was conceived and built. How It Works Two prototype units were fabricated and have been field tested by MSHA technical support engineers in under-ground mines. The equipment consists of an electronics Package 20 x 24 x 8 inches and weighing 93 pounds, including a side-mounted circuit breaker, with a set of 8 foot long detachable, AWG #4/0 leads with plier-type clamps. The total lead assembly weighs 21 pounds.

Jan 1, 1981

By Thomas P. Holden, Todd M. Ruff

Problem: An average of three workers a year are killed in surface mining operations when a piece of haulage equipment collides with another smaller vehicle or a worker on foot. Another three workers are killed each year when haulage equipment backs over the edge of a dump point or stockpile. Devices to monitor the blind areas of mining equipment are needed to provide a warning to operators when a vehicle, person, or change in terrain is near the equipment. Method: A proximity warning system (PWS) based on the global positioning system (GPS) and peer-to-peer communication has been developed to prevent collisions between mining equipment, small vehicles, and stationary structures. Results: A final system was demonstrated using one off-highway haul truck, three smaller vehicles, and various stationary structures at a surface mining operation. The system successfully displayed the location of nearby vehicles and stationary structures and provided visual and audible warnings to the equipment operator when they were within a preset distance. Summary: Many surface mining operations already use GPS technology on their mobile equipment for tracking and dispatch. Our tests have shown that it is feasible to add proximity warning to these existing systems as a safety feature. Larger scale and long-term tests are needed to prove the technology adequately. Impact on Industry: A PWSs that incorporates a combination of technologies could significantly reduce accidents that involve collisions or driving over an edge at surface mining operations.

By R. B. Schluter

The Bureau of Mines investigated the flotation responses of two copper-nickel ore samples from the Duluth Complex with the objective of recovering bulk sulfide concentrates. One of the ores studied was taken from a test pit; the other was taken from a test shaft. The samples were quite similar except that the pit sample analyzed 0.35 pct Cu and 0.11 pct Ni and the shaft sample analyzed 0.69 pct Cu and 0.14 pct Ni. Flotation responses were studied in both laboratory and pilot plant tests. Pilot plant flotation responses were similar for both samples resulting in grades of 12.2 pct Cu and 2.5 pct Ni for the pit sample and 12.2 pct Cu and 2.1 pct Ni for the shaft sample. Weight recoveries were 2.5 pct for the pit sample and 5.2 pct for the shaft sample. Copper and nickel recoveries for the pit sample were 87 and 62 pct, respectively, and 92 and 73 pct for the shaft sample. Both concentrates contained small but significant values of cobalt and precious metals. Cobalt recoveries were low--less than 40 pct for both concentrates. Precious metals contents of the concentrates were 1.59 oz/ton for the pit sample and 0.99 oz/ton for the shaft sample. Silver was the predominant precious metal by weight, but platinum and palladium represented the highest values.

Jan 1, 1980

By Ronald D. Hill, Elmore C. Grim

Sediment is one of America's greatest pollutants. More than a billion tons of sediment reach the major streams of the United States annually(l). Damages are reflected in the reduced carrying capacity of streams, clogged reservoirs, destroyed habitat for fish and other aquatic life, filled navigation channels, increased flood crests, degraded facilities for water-based recreation, increased industrial and domestic water treatment costs, premature aging of lakes by enrichment of the water with silt-carried fertilizer that promotes algae growth, destroy crops, and reduce productivity of flood plain soils. Erosion and sedimentation are natural processes that are usually gentle actions releasing controlled amounts of silt from watersheds to receiving streams. Surface mining activities accelerate these natural processes and short duration, high intensity storms can become a violent force moving thousands of tons of soil in a brief period of time. Cover is a very important factor. With the removal of ground cover, water moves across the denuded area on its own terms picking up soil particles as it flows and leaving gullies behind. The susceptibility of strip-mined land to erosion depends on: 1.Physical characteristics of the overburden 2. Degree of slope 3. Length of slope 4. Climate 5. Amount and rate of rainfall 6. Type and percent of vegetative ground cover. By development of erosion and sedimentation control plans before disturbance of the area, many of the detrimental effects of strip mining can be prevented.

Jan 1, 1974

By Nicholas Kyriazi

Significant portions of the present Federal regulations for certification of closed-circuit breathing apparatus (42 CFR 84) are not quantitative. The human-subject testing portion of the regulations specifies activities rather than metabolic work rates; however, heavy human subjects have higher oxygen consumption, CO2 production, and ventilation rates than lighter human subjects performing the same activities. This means that apparatus certified using different human subjects have effectively passed different tests. In addition, apparatus performance is monitored only during selected intervals of testing, and always during rest, rather than during the entire performance period. Further, testing is arbitrarily terminated at specific rated durations, leaving unknown the performance during the remaining duration. Duration itself is misleading to users who believe that the apparatus will last a certain time no matter how much they weigh or how hard they work. The actual duration obtained from an apparatus, however, is highly variable, being inversely proportional to the work rate at which it is used. In this report, recommendations are made to (1) replace the present regulations for certification of closed-circuit breathing apparatus with quantitative tests specifying metabolic work rate rather than activity,(2) continuously monitor relevant physiological stressors, (3) continue testing until exhaustion of the oxygen source, and (4) classify closed-circuit breathing apparatus by quantity of usable oxygen, i.e., capacity, rather than by duration. Physiology-based stressor levels are suggested as well.

Jan 1, 1999

By Paul S. Lewis

The Bureau of Mines hydrogenated coals of different rank that had been irradiated with either x-rays or gamma rays. Lignite, high-volatile A and C bituminous, and low-volatile bituminous coals were exposed to l billion roent¬gens of gamma-ray radiation; specimens of high-volatile A and C bituminous coals from other sources received 6 million roentgens of X-ray radiation. Irradiated and unirradiated control specimens of those coals were hydrogenated in autoclave experiments at (6,000-p.s.i. final pressure and 400° C. with retention times of 15, 30, or 60 minutes depending on the coal rank and catalytic treatment. Comparison of results from irradiated specimens with those from the control experiments showed that the radiation had no beneficial effect on the coal. High-volatile C bituminous coal may have been affected by radiation more than the other coals. One billion roentgens appeared to reduce the amount of coal converted to liquids and gases by about 10 pct., and 6 million roentgens reduced it by about 6 pct. then catalyzed with tin. In all other cases, the conversion of irradiated coal was either reduced by as much as 4 pct. or was essentially the sank as that obtained with unirradiated coal. Irradiation during hydrogenation nay be effective for increasing the reactivity of coal and should be investigated; further work with coals irradiated prier to hydrogenation is not recommended.

Jan 1, 1962

By Charles G. Patmon

This paper describing the methods of dredging and treatment of gold-bearing gravels at the Lancha Plana Gold Dredging Co.'s dredge is one of a series of similar papers being prepared by the Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The dredge is located near the Mokelumne River, 12 miles west of San Adreas, Calif.; it is accessible by an improved dirt road from Jackson, which is about 20 miles distant.

Jan 1, 1932

By John W. Chandler

The property of the lava Cap Gold: Mining Corporation is in the Nevada City-Grass Valley mining district about 5 miles east of Crass Valley, Calif. At present (July 1940) the plant is mining end milling about 390 tons of gold-silver ore a day; about 310 men are employed. This paper describes the mining methods used and presents mining costs for 1939, when 60,704 tons were mined by cut-and-fill stoping and 55,676 tons by square-setting.

Jan 1, 1941

By Vern L. Kegler

This paper is one off a series dealing with mining methods and costs, sponsored and published by the United States bureau of Mines. ACKNOWLEDGMENTS The author acknowledges the, constructive and helpful suggestions and criticism of W. F. Lamoreaux, vice-president, and general manager of the Ducktown Chemical & Iron Co. United States Geological Survey Professional Paper- 139, by W. H. Emmons and F. B. Laney, has been drawn upon for some of the information contained in the paragraphs or history and geology.

Jan 1, 1931

By J. E. Tress

The Bureau of Mines has developed a process to utilize waste heat from electric arc steelmaking furnace gases to preheat the ferrous material charged to the furnace. Four heat exchangers were designed, tested, and operated successfully on 1-ton electric arc furnaces. Briquets and pellets were charged continuously, both countercurrent to the hot furnace offgasses and at ambient temperatures. A comparison of the electrical energy consumed in each situation showed that preheating can lower energy requirements as much as 15.6 percent.

Jan 1, 1975

By H. S. Auvil

[The shrinkage of coke after formation is one of the variables that effects the net expansion of the change in both industrial and test ovens. Various test results5/ have been interpreted as indicating that cokes from certain coals shrink to a marked extent and that other cokes show very little shrinkage; but no comprehensive experimental study of the shrinkage of coke after its formation and of the factors influencing this shrinkage has come to the attention of the authors.]

Jan 1, 1940

By C. J. Chindgren

A refractory-lined, garage-type automobile incinerator with a natural gas afterburner for air pollution control was cooperatively constructed and tested by the Bureau of Mines and the Wasatch Metal & Salvage Co. in Salt Lake City, Utah. The incinerator is capable of relatively smokeless burning of 32 to 60 cars per day, dependent on the degree to which the cars are stripped prior to incineration. Preliminary burning campaigns indicate the cost of incineration to be approximately $2.75 per car.

Jan 1, 1970

By Graham W. Marks, RALPH MILLS, FRANK COSSEY

To determine the focal length of lenses or the performance of lens systems before mounting them permanently , it is desirable to have a device in which one or more lenses can be mounted easily and their positions relative to a light source and screen changed readily . We have designed and constructed such an optical bench and lens holder . The bench is similar to that of Houstoun5/ but has been modified , whereas the lens holder is , we believe , a new design .

Jan 1, 1948

"Requests are frequently received by the Information Service of the Bureau of Mines for published information on the coals of different foreign countries, as compared with coals mined in the United States. The analyses of various coals from several countries on the Pacific, which were submitted to the Fuels Division for certain tests between the years 1913 and 1916, may be of interest, and are shown below: Results of Analyses of Various Coals from China, New Zealand, Japan and Australia."

Sep 1, 1925

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

By Neil B. Young

Analytical results for nahcolite, dawsonite, total extractable alumina, and oil yield are presented for samples representing Green River Formation oil shales in the saline section of two cores from Colorado's Piceance Creek basin. Analyses are also reported for samples extending the analyzed section of Colorado corehole No. 3 beyond that reported previously. These data permit evaluation of the deposit for possible production of three coproducts--shale oil, alumina, and sodium carbonates--from the saline section of the formation at these sampled points.

Jan 1, 1970

By Dean E. Bluman

The Bureau of Mines investigated the convective heat transfer coefficients for recirculated suspensions of 30-micron glass beads in inert gas. Coefficients for the suspensions were not significantly higher than coefficients for the pure gas. Reynolds numbers of the suspensions were 20,000 to 35,000; solids loadings ranged from 0.0 to 0.7 pound per pound of gas. Comparison of the results with published data showed the direction of heat flow to have no effect at the test conditions.

Jan 1, 1967