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By James C. Ault, Walter W. Kaufman

This Bureau of Mines manual for design of surface mine haulage roads covers such aspects of haulage road design as road alignment (both vertical and horizontal), construction materials, cross slope, and drainage provisions. Traffic control and design of proper lane widths to promote safe vehicle movement are included, as are suggested criteria for road and vehicle maintenance and for runaway vehicle safety provisions. The aim of this publication is to provide those involved with surface mine haulage road design with a complete manual of recommended practices that, if implemented, will promote safer, more efficient haulage routes.

Investigate the use and placement of lightweight concrete to improve ground control technology in deep mines where deformation occurs under heavy ground conditions and where there is danger of rock bursts. Approach Investigations of lightweight concrete properties and placement methods were conducted in the laboratory and in the field. Three test sections were completed: a monolithic, portal-type structure with integral walls and arch constructed aboveground; an underground test section constructed in a mine drift using plywood forms; and a test section constructed in a mine drift using an air-supported formwork. In the two underground test sections, the light-weight concrete was placed using a piston pump with concrete discharge line. A cooperating mine also used lightweight concrete, in the density range of 25 lb/ft3, to replace timber blocking in a raise preparation structure (the enlarged area across a vein where chutes and manway access arc placed). Other experiments included the use of precast lightweight concrete blocks in situations where ground support was needed, such as fur mine, ventilation doors, stoppings, and barricades.

Jan 1, 1990

By M. A. Trevits, S. W. Lambert

In this Bureau of Mines investigation, production was monitored for 1 year at over 30 coalbed gas-drainage boreholes located in Alabama, Pennsylvania, and West Virginia. Results indicate that the quality of data gathered from such wells can be improved greatly if potential problems are anticipated and prevented in the early stages of well production. Major water-monitoring problems include solids buildup, freezing, the presence of gas in surface waterlines, and improper pumping interval settings. Such problems may be avoided by incorporating in the original well design waterline filters, sand screens, separator tanks, and systems to automatically control pumping intervals. Problems related to measurement of coalbed gas flow include large quantities of water vapor contained in the gas, especially during winter months; freezing and subsequent obstruction of flow; sudden, uncontrolled release of gas pressure; and solids buildup in metering equipment. The installation of commercially available items, such as filters, separators, and insulation, and the thoughtful application of a basic knowledge of coalbed gas reservoir characteristics will prevent most production-monitoring problems.

Jan 1, 1978

The Bureau of Mines Minerals Information organization collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. This data collection activity was instituted by the 47th Congress in an appropriations act of August 7. 1882 (22 Stat. 329), to place the collection of mineral statistics on an annual basis. The most recent authority for the Bureau of Mines Minerals Information activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress), which strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1985

By Ruth A. Holmes

A Bureau of Mines method for recovering nickel, cobalt, and copper from low-grade domestic laterites is described, which includes the unit operations of solvent extraction and electrowinning. Previous Bureau work indicated that addition of Na2S04 (sodium sulfate) to the nickel electrolyte improved current efficiency in nickel electrowinning. The present study determines the compatibility of Na2S04 with nickel strip-ping in the solvent extraction operation of the Bureau method. The effect of adding 100 g/l Na2S04 on nickel stripping, phase disengagement, and pH was determined in comparative laboratory-scale tests. In continuous-circuit testing, Na2S04 reduced stripping efficiency to the extent that five, instead of four, strip stages were required for complete stripping of nickel from the loaded solvent. In tests made in a phase-disengagement cell that had a variable settler area, the addition of Na2S04 did not significantly affect phase separation characteristics. The pH of the nickel electrolyte in the temperature range of 20° to 65° C was also unaffected by the addition of Na2S04. An economic evaluation showed that the energy saved by adding Na2S04 to the electrolyte would more than offset the cost of adding another stripping stage.

Jan 1, 1983

By Launa G. Mallett, Kathleen M. Kowalski, Michael J. Brnich

The characteristics of leaders under the duress of an emergency are important in the development of emergency planning, training, and in the management of an actual emergency. Knowledge of human behavior is an important component in the formation of emergency strategies. The U.S. Bureau of Mines analyzed the leadership behavior in three underground mine fire escapes. The subjects described their escapes during open-ended interviews. Data were coded according to: (1) evidence of leadership behavior, (2) evidence of lack of leadership behavior, and (3) characteristics of the individual in each group who led the subjects out of the mines. This paper discusses the profile of six individual leadership characteristics which emerged from the data.

By M. K. Larson, J. K. Whyatt, R. B. Langston, J. C. Johnson, H. Kirsten, T. M. Brady

An experiment is described in which hollow inclusion cells (HICells) were used to measure stress in a jointed rock mass during drift development at the Stillwater Mine, Nye, MT, USA. Two HICells were installed in the footwall approximately two drift widths ahead of the face. One HICell was over cored and then immediately tested in a biaxial chamber. The other HICell was left in place and monitored as the drift was excavated in three advances, each one-half the width of the drift. Strains were recorded hourly by a datalogger. Results show that there was little stress change during the first and second drift advances, but that a large stress change occurred after the third advance. The measurements also showed that the in situ principal stress directions lined up with regional geologic structures. Stress changes during face advance were likely caused by deformation along localized joint sets and inelastic deformation near the face.

By Karl R. Becker

Detonators representing a sampling of various domestic commercial delay detonators were fired at various direct-current (dc) firing levels. Results of firings using well-below-recommended firing levels showed marked increases in delay times above the nominal values. There was also a marked increase in variation, to the extent that out-of-sequence firings would be essentially assured in any typical blasting round at these low firing levels. Within the range of recommended levels the effects of current increases were not considered to be of great importance relative to other overriding effects, such as the significant difference noted in average values of detonators from different lots having the same nominal delay. This effect, when combined with the normal variation noted among members from the same lot, would cause out-of-sequence firings with detonators from a neighboring delay period. Where comparisons with results from another study were possible, it was found that both studies observed quite similar variations in delay times about the average values, and a lower probability of out-of-sequence firings for the shorter delay period groups. The criterion of the previous study for assessing the likelihood of observing out-of-sequence firings, when applied to the Bureau of Mines data, properly identified two neighboring delay period groups where out-of-sequence firings would occur.

Jan 1, 1981

By Richard O. Kneisley

Microseismic activity observed in both the laboratory and underground indicates that a quiet period, associated with the closure of existing fractures and strongly influenced by coal seam microstructure, occurs prior to coal bumps. Field studies conclude that coal mine bumps occur against a background of this so-called microseismic calm. This Bureau of Mines report summarizes microseismic activity associated with face bumps and floor bursts in a deep, western U.S. coal mine. Results conclude that while bumps are often accompanied by panel-wide increases in microseismic activity, bumps are not only preceded by a localized decrease in activity, but occur within these quiet zones. The results of this study concluded that microseismic activity may be applicable to the global detection of potential bump-prone zones, but that future studies are necessary to confirm these findings and to improve the techniques for evaluating stress control effectiveness.

Jan 1, 1989

By Oliver Bowles

"In a previous report of the Bureau of Mines (Serial No. 2080 reference was made to a fatal accident from falling rock in a quarry in Utah, and ways of avoiding such accidents were pointed out. A fatal accident similar to it in some respects recently occurred in a limestone quarry in Maryland. All operators of stone quarries are desirous of reducing accidents to a minimum, and almost without exception they welcome any suggestions having in view the establishment of safer quarry practice. It is believed, therefore, that a brief outline of the cir-cumstances surrounding this later accident may be of practical advantage to quarry-men, as it may serve as a guide to them in so conducting operations that such unfortunate occurrences may be reduced in number.The quarry where the accident occurred is in form a circular pit 500 to 600 feet across an 80 to 100 feet deep. The rock is a dense limestone with the beds dipping at an angle of 35 to 45 degrees from the horizontal. Numerous erosion cavities in the form of pockets or narrow spaces following joint planes are filled with red sand and clay. They are confined largely to the upper 20 or 30 feet of the deposit. Open bedding planes are 4 to 10 feet apart toward the surface, and are spaced at wider intervals toward the base of the quarry. The open bedding planes present smooth uniform rock surfaces that dip steeply into the pit at the northeast side of the quarry opening. These smooth surfaces constitute a source of danger, as they may permit loose material to slide into the pit.In this particular instance a blast had been discharged, throwing down a mass of rock for steam-shovel loading. Three men wore employed thereafter for a period of about two days in cleaning down all loose material that might be dangerous to workmen luring the loading process. A mass of red sand and clay in which several large bowlders were embedded was left on one of these slanting surfaces, for the material seemed to be sufficiently secure to be quite safe. The lower edge of the slanting surface was about 25 feet above the quarry floor. The quarry conditions are illustrated in fig. 1, where (a) represents the quarry floor, (b) the vertical quarry (c) the slanting joint plane surface, and (d) the rock and earth resting on the surface."

Dec 1, 1921

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

APPENDIX A - PNEUMATIC TRANSPORT OF FLY ASH 1. Introduction Two types of pneumatic transport of fly ash are critical to the success of (1) Transport of fly ash from the fly ash truck to the entrance to the borehole. Depending on the surface topography, this may be horizontal, decential and ascential. (2) Vertical downflow of fly ash through the borehole. All fly ash trucks have limited pressure with which they can pump the fly ash. Thus, the pressure drop in the fly ash hose will define the maximum length for pumping and consequently the maximum distance that the fly ash truck can be parked from the auxiliary blower. The same relationships describe the flow of the dilute fly ash-air mixture produced by mixing with the auxiliary air from the blower and thus define the selection of the pipe diameter. These are im¬portant considerations in the proper selection of the location of the passages to be sealed and the type of surface preparation required. The flow characteristics of fly ash down the borehole determine the selection of the minimum borehole diameter and the blower pressure. This appendix presents theoretical analyses of these flow regimes and summarizes the limited experimental data obtained during the field tests at Grant Town, described in Section 8.4. The analysis for the borehole flow is presented first as it is of greater interest to the program. This is followed by a discussion of the horizontal flow.

Jan 1, 1973

By Roy H. Grau

The National Institute for Occupational Safety and Health (NIOSH) has conducted research to improve the ventilation of large-opening mines whose entries are at least 93m2 (1,000 ft2). The ventilation of large-opening mines is unique compared to other types of mines because (1) it is challenging to keep airflow velocities high enough to effectively remove or dilute airborne contaminants because the entries are so large, (2) large air volumes can be moved through the mines with little static pressure drop, and (3) stoppings that are used to direct ventilation airflows are costly to construct and to maintain. The research results suggest that the ventilation of large-opening mines is improved significantly by incorporating ventilation planning into the mine planning process, using propeller fans to direct airflow, developing new stopping materials and construction methods, and using long pillars to eliminate crosscuts where possible.

Jan 1, 2009

Provide guidance on the selection of millisecond initiator delays between blastholes in surface mine blasting to provide a desired degree of rock fragmentation consistent with safety and vibration considerations. The Problem Blasting remains the primary means of fragmenting, rock for all kinds of mining, quarrying, construction, and excavation activities, and it is the only practical and economic method of breaking up and moving large amounts of material such as coal overburden and stone aggregate. Because of the large amount of blasting done, typically using 4 billion pounds of explosive to break about 8 billion tons of rock annually in the United States, a small improvement in blasting performance will have a significant productivity impact. Standard blasting practices involve the selection of time delays in a blast for at [cast three purposes: (1) to control energy flow to minimize adverse vibrations, (2) to provide sufficient time relief for good rock displacement, appropriate muck pile shape for digging, and the prevention of collar violence, misfires, and flyrock, and (3) to provide an appropriate amount of interhole stress wave and gas pressure action for a desired fragmentation size distribution. Timing guidelines that exist are based on subjective observations rather than measurements, even for the relatively new casting methods. Until this Bureau study, no definitive analysis had been done to quantify the fragmentation and productivity of full-scale blast rounds as functions of precision delay timing.

Jan 1, 1989

By T. L. Joseph

"In the January 3 issue of Iron Trade Review, Sweetser2, in referring to the problem of coke combustibility, points out that, ""Someone should formulate a rule for the rate of flow of coke through the zone of coke combustion that now appears to be confined to a comparatively restricted volume in front of the tuyeres,"" In formulating such a rule it is necessary to distinguish clearly between combustibility, a property of the fuel, and rate of combustion, which is determined by the rate at which air is supplied to the fuel bed. The rate of carbon gasified at the tuyeres of a blast furnace is independent of coke combusti-bility. A fast-burning coke will burn in a more restricted volume than a slow-burning coke, but both types of fuel will be consumed at rates determined by the supply of oxygen,A number of the definitions of combustibility that have appeared in technical literature relate more closely to rate of combustion than to combustibility. Perrott and Kinney) have correctly defined it as follows: ""Combustibility of coke from the standpoint of its use in, the blast furnace is inversely proportional to the mean rate of gasification per unit volume of the combustion zone, assuming other factors remain constant,"" Combustibility of coke refers therefore to those properties that determine the size or extent of the combustion zone. Relative differences in these properties can be measured by the depth of the fuel bed required to convert oxygen from the air into carbon monoxide."

May 1, 1924

By Todd M. Ruff

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are studying methods to prevent workers from being entangled in machinery used at mining operations. An analysis of mining accidents in the United States that resulted in a fatality or permanent disability from 2000 through 2005 showed 438 severe incidents that involved contact with machinery or equipment, an average of 73 per year. Researchers determined that the most common machinery involved in these severe accidents was conveyors. Also, a significant portion of the accidents occurred during machine maintenance and repair. Researchers are focusing on improved methods to prevent unintentional machine startup during maintenance activity and methods to detect workers near moving machine components. One new technology that shows promise for this application is intelligent video. Popular in the surveillance and security industries, these systems use cameras and computerized video analysis techniques to automatically detect the presence of people in preset zones within the camera?s field of view. A preliminary study has been initiated to determine if this technology could reliably detect the presence of workers in hazardous locations near machinery. Possible advantages of the use of this technology include improved detection zone demarcation and improved ability to distinguish between hazardous and non-hazardous proximity, compared to conventional proximity sensor techniques. Initial tests to detect a person near a conveyor system in daylight conditions showed promising results. A description of the technology, test procedures and results, implementation challenges, and future research needs are discussed.

Jan 1, 2008

Decrease dust concentra¬tions of longwall face workers by keeping them up¬wind of the headgate stage loader and crusher. Approach Direct the face airflow from tailgate-to-headgate, the direction of coal transport. How It Works Ventilation is the primary method of dust control on longwall faces, and the most effective ventilation control is to put workers upwind of dust sources. Recent ad¬vances in longwall dust sampling by the Bureau have shown that on some faces, the headgate crusher and transfer points are signifi¬cant sources of dust -some¬times making up more than half of the total dust to which the face workers are exposed. Also, when the air is coursed from head-to-tail, the relative velocity between the air and moving coal on the face conveyor can cause dust entrainment from the conveyor, particularly if the coal is dry. On the faces where these dust sources are a signifi¬cant problem, they may be eliminated by coursing the air from tailgate-to-headgate, provided that the mine roof is stable enough to permit the necessary intake of the tailgate along with an aux¬iliary intake at the headgate.

Jan 1, 1982

By Philip A. Holland

The Bureau of Mines has developed a method for determining helium in water for use in sampling and analyzing surface and subsurface waters for geochemical survey work. The accuracy of the analytical method is within ±10 percent for samples containing above 20 x 10-8 cm3 He (STP)/cm3 H20. The minimum detectable helium-in-water concentration is calculated to be 2 x 10-8 cm3 He (STP)/cm3 water. Water samples are collected in 500-cm3 stainless steel cylinders. The dissolved gases are extracted into a cylinder of equal volume containing a known quantity of neon. The resulting gas mixture is subsequently analyzed for helium and neon-21 by mass spectrometry. The volume of helium in the sample is calculated from the mass spectrometric determination of the helium-to-neon-21 ratio, the known quantity of neon used, and the extraction efficiency of helium.

Jan 1, 1981

By S. C. Tadolini, T. M. Barczark

Mines in the western United States have had limited choices for standing support. Wood cribs were often too soft and unstable. The introduction of the Can support in the earl v 1990s provided an effective alternative, (lilt/ it remains the dominant form of tail¬gate support. Water-filled prestressing cells are now used to cap the Can and preload it to provide an active roof load. The Cluster Prop, consisting of three timber wedge props bundled to¬gether; provides more capacity than (m equivalent sized Call support and improves transport efficiency. However the Cluster Prop is less stable and does not maintain a consistent load throughout its loading profile. Pumpable roof supports are another alternative support, but the \' have not been proven in high deformation en¬vironments. This paper compares the performance characteristics o f these various support systems.

By Robert P. Vinson

A sequential sampler, based on the Archimedes screw, has been developed by the Bureau of Mines. Its initial purpose was to collect air samples during tracer gas studies in underground mines. However, the basic concept can be applied to other sampling needs, including sampling of liquids. A prototype was built and successfully tested in the Bureau's Experimental Mine at Bruceton, Pa. The simple design makes the sampler inherently durable and low in cost.

Jan 1, 1976

By R. F. Waters

The Bureau of Mines developed laboratory-scale processes to recover sodium phosphates and metal values from waste sludges generated by the phosphate treatment of automobile and appliance components. After treatment of the sludge with NaOH, followed by coke or hydrogen reduction and sintering, zinc and lead were recovered as fume; the sinter was separated by leaching into a metallic product, chiefly iron and nickel, and high-purity disodium or trisodium phosphate.

Jan 1, 1971