Search Documents

By R. C. Ellman

Significant effects of in-the-mill drying on the pulverization of lignite have been demonstrated in an experimental impact-type pulverizer by tests in which the primary variable was temperature of the sweeping gas. Reduced power requirements and increased product fineness were observed as the extent of drying was increased. Pulverization with in-the-mill drying was studied in comparative tests made on lignites from five mine sources. All of the lignites responded in a similar manner; however, differences in the pulverizing characteristics of the individual lignites were significant. For one lignite, the electrical input to the pulverizer driving motor with minimum sweeping-gas temperature was 33.9 kw.-hr. per ton, decreasing to 14.0 kw.-hr. per ton with a sweeping-gas temperature of 658° F.; for another lignite, at comparable operating conditions, the electrical input decreased from 59.1 to 19.0 kw.-hr. per ton. In the first case, the product fineness increased with increasing temperature of sweeping gas from 65.2 to 79.2 percent through a 200-mesh sieve, and in the second case, from b2.7 to 86.9 percent through a 200-mesh sieve.

Jan 1, 1962

By A. J. Keast

This circular is one of a series dealing with the exploration, equipping, and development of mining properties, prepared and published by the United States Bureau of Mines in cooperation with various mining and exploration companies in the United States and Canada. This series of papers will supplement an earlier one which covered the methods and costs of mining and milling at a large number of producing mines. The present paper describes the exploration, equipping, and developing of a group of 18 claims remote from rail transportation, and the transport of equipment and heavy supplies for a distance of 120 miles by tractor over ice and winter roads, and of men and lighter supplies by airplane.

Jan 1, 1933

By Fred Leighton

The least squares method of rock noise source location presented is shown to be more accurate and reliable than standard direct solution methods. This method is particularly effective in improving solutions from rock noise locations outside of geophone array boundaries. A least squares solution for a medium .in which the seismic velocity is the same in all directions is also presented. In this special case, one can solve for both the source coordinates and the velocity.

Jan 1, 1972

By Donna lynne Anderson

This report documents the status of a laser-based underground guidance system for tracking and controlling the movements of underground mobile mining equipment. This research is part of a multiple project effort at the U.S. Bureau of Mines to increase mine safety and efficiency by developing technology for computer-assisted mining. Guidance systems, which can track and control the movements of underground mining equipment, are essential during computer-assisted mining operations. A continuous mining machine at the Bureau's surface test facility served as the test-bed for initial development and experimentation of this guidance system. Subsequently, a continuous mining machine in an underground mine served as the platform for in-mine experimentation. The first section of this report includes details of the laser sensors, communication network, and computer hardware. The next section includes experimental results, which show the system capable of accurately tracking and controlling the tram maneuvers of a continuous miner underground. The final section discusses conclusions and recommendations.

Jan 1, 2010

By J. H. Stears

This Bureau of Mines report presents information on the use of steel supports in U.S. coal mines, including accident statistics for a 3-yr period and a survey of present applications and problems. It also contains a summary of available steel arch configurations and a description of steel support design criteria for ground control applications.

Jan 1, 1984

Introduction The NIOSH Office of Mining and Construction Safety and Health Research has redesigned its Mining Safety and Health Web topic page. The updated page incorporates a significant amount of new safety and health information, plus an improved layout to better serve stakeholder needs. It also provides back-ground information about the NIOSH Mining Research Program, including research awards, core competencies, unique labs, community and educational outreach, and a brief discussion of how the research program is structured. The new Web topic page can be found at www.cdc.gov/niosh/mining. "Search" Feature The redesigned Web topic page features improved search capabilities. The "Search Mining" feature on each page lets you search only the NIOSH Mining Safety and Health Web topic page. The user can still search the entire NIOSH Web page by using the "Search NIOSH" option. New Safety and Health Topics Developers expanded the "Safety and Health Topics" and reorganized the site to make it easier to find information. Each topic link now has a significant amount of new and updated information, as well as links to related topics of interest. Safety and health topics include dusts, diesel exhaust, hearing loss, contact with electric current, fires, explosives, ventilation, emergency management, new and older workers, and education and training. All topics can be accessed from the home page (Figure 1). Publications Although the Web topic page highlights many of the most requested publications on the safety and health topic links, you can find a complete list of downloadable publications as well. More than 600 mine safety and health publications are now downloadable from the page. Short summaries let the user quickly identify publications of interest. Products The updated Web topic page offers more than 120 NIOSH mine safety and health products, including training exercises, toolbox talks, videos, computer software, guides, and checklists, many of which are downloadable. If not, instructions are given on how to obtain copies. Some of our products include: • Software to analyze horizontal stress, design pillars for longwall mines, and select roof bolts for ground control. • Educational software including the Hearing Loss Simulator, which simulates the effects of noise and aging; and Coal Country, which teaches children about coal formation, mining techniques, and everyday uses of coal. • Utility software including the HazCom Helper software to assist individuals in writing a HazCOM plan, as required by the Mine Safety and Health Administration (MSHA), to track hazardous chemicals at their mine sites. • Guides for troubleshooting roof support systems, under-ground workstation design, and seating design. • Training exercises and videos that can be used for safety training. Data and Statistics General mining statistics are used by a wide variety of stakeholders. The NIOSH Mining Web topic page offers statistical graphs, tables, maps, fact sheets, and other publications that document the mining population, injuries, fatalities, diseases, and occupational exposures for all mining commodities. If users prefer to analyze data themselves, downloadable files of MSHA data are available. These cover employment, production, injuries, fatalities, and accident data from 1983 to the present and are available in both SPSS® and dBASE® formats.

Jan 11, 2005

By K. E. Hjelmstad

During an underground mine fire, air can be rapidly depleted of oxygen and contaminated with smoke and toxic fire gases. Any delay in warning miners could have disastrous consequences. Unfortunately, present mine fire alarm systems, such as stench, audible or visual alarms, telephones, and messengers, are often slow, unreliable, and limited in mine area coverage. Recent research by the U.S. Bureau of Mines has demonstrated that ultra low frequency electromagnetic signaling can be used for an underground mine fire alarm. In field tests of prototype equipment at five mines, electromagnetic signals from 630 to 2,000 Hz were transmitted through mine rock for distances as great as 1,645 m to an intrinsically safe receiver. The prototype system uses off-the-shelf components and state-of-the-art technology to insure high reliability and low cost. When utilized, this. technology would enable simultaneous and instantaneous warning of all underground personnel, regardless of their location or work activity, thereby increasing the likelihood of their successfully escaping a mine disaster. This report presents the theoretical basis for through-the-rock ultra low frequency electromagnetic transmission, design of the prototype transmitter and receiver, and the results of in-mine tests of the prototype system.

Jan 1, 2010

Most laboratory sealant studies were carried out in 2.0 inch I.D. Plexiglas tubes of 9.0 inches height containing 4.0 to 4.5 inches reconstructed soil from an 0-8 or 8-16 inch soil horizon at the Lanse site. (When soil was used from the Kato site, the top soil horizon was approximately 0-4 inches. The 4-8 inch horizon was somewhat comparable to the Lanse 8-16 inch horizon.) A 20 mesh Saran or steel screen was placed over the rubber stopper with a bottom drain to a 100 ml measuring cylinder. In some earlier experiments a 1/2 inch bed of 1/4 inch pea-gravel was then added, but in later experiments this was eliminated as it showed no particular utility. Field soil samples collected by a shovel were stored in sealed containers and sieved through a 4 mesh screen just before use. (Moisture content was typically about 25% for A horizon soil and about 20% for B horizon soil.) The sieved soil minus roots was then added in increments of about 1 1/4 inches. Compaction was effected by dropping a weighted ramrod (1-7/8 inches O.D,) five times from a height of two inches. If about twenty tamps were used or if the soil columns were rapped vigorously while water-logged, compaction was high with no detectable percolation. Freezing such samples would then usually cause very slow percolation, e.g. 1-2 ml/day. Using this as a standard procedure, percolation flows were usually stablized after two to three days to rates of about 100 to 200 ml/hour. Percolate was recycled carefully to minimize disturbance of the soil surface. When percolation flows were about 100 to 200 ml/hour, various additives (sealants) were introduced to the moist column in two to three increments to maintain a slight head. Additive concentrations were usually 2-1/2% with some at 5% in earlier experiments. Typical use of 40 ml of 2-1/2% additive corresponds to 4400 lbs/acre. When no more additive was present as supernatent liquid, water washes of about 15 ml were then used several times followed by special additives as needed. More water washes were then used to maintain a head of about 1/2 inch. Percolate was collected in 100 ml cylinders to measure percolation rates in ml/hr. Turbid percolate was evaporated to determine amount of eluted latex. Percolate was sometimes checked for pH by Pan-pH Indicator Paper9,10 reading in 0.5 units. Surface tension measurements were sometimes made by a DuNouy tensiometer10 in experiments using a surfactant for pretreatment.

Jan 1, 1972

By F. P. Haver

A procedure is described for recovering both lead and sulfur from galena flotation concentrate, comprising the following steps: (1) Aqueous oxidation of the concentrate, using ferric sulfate to convert lead sulfide to sulfate and to give elemental sulfur; (2) regeneration of the ferric sulfate by electrolysis in a diaphragm cell; (3) treatment of the leach residue with ammonium carbonate solution to change the lead to an acid-soluble form and to produce ammonium sulfate as a byproduct; (4) solution of the lead carbonate in hydro-fluosilicic acid followed by electrolysis to recover the lead as metal and regenerate the acid; and (5) extraction of the elemental sulfur from the final residue with an organic solvent. About 90 percent of the lead can be recovered by the above method as 99.9-percent-pure metal, together with two-thirds of the sulfur--half in the elemental form and half as ammonium sulfate.

Jan 1, 1970

By Tobias W. Goodman, Joseph Cervik

This Bureau of Mines report investigates the horizontal trajectory of boreholes drilled in coalbeds using the rotary drilling technique. Test holes drilled in coalbeds showed that the path of a borehole in the horizontal plane depends on drilling assembly configuration, drill bit rotation, and coalbed geologic features. An assembly that contained an 18-ft (5.53) long drill collar and two centralizers had the best horizontal stability evidenced by trajectories that deviated less than 16 ft (4.9 m) from a target at 1,000 ft (305 m). Removal of one of the centralizers resulted in a loss of control of hole trajectory in the horizontal plane. Generally, holes tended to turn to the right, presumably because of right-hand rotation of the bit. Deviations from the original bearing line were as much as 200 ft (61 m) or more at a depth of 1,000 ft (305 m).

Jan 1, 1988

By John J. Sammarco

Computer-related accidents have caused injuries and fatalities in mining as well as other industries. Normal accident theory (NAT) explains that some accidents are inevitable because of system complexity. NAT is a classic argument in organizational sociology although it has been criticized as having imprecise definitions and lacking criteria for quantifying complexity. These limitations are addressed by a unique approach that recasts this organizational theory into an engineering-based methodology to quantify NAT complexities of computer-based systems. In this approach complexity is categorized as external or internal. External complexity is defined by the external behavior of a system, and is quantified by these dependent variables: system predictability, observability, and usability. Dependent variable data contain the perceptions of 32 subjects running simulations of a system. The system?s internal complexity is characterized by modeling system-level requirements with the software cost reduction (SCR) formal method. Model attributes are quantified using 15 graph-theoretical metrics?the independent variables. Five of 15 metrics are correlated with the dependent variables as evidenced by structure correlations exceeding 0.25, with standard errors <0.10 and a 95% confidence interval. The results also show that the system predictability, observability, and usability decreased as NAT complexities increased. This research takes a step forward in operationalizing NAT for computerized systems. The research benefits mining and other industries as well.

Jan 1, 2005

By W. J. Fene

It is often desired to obtain samples of air in places where collection by ordinary methods is not feasible, as in shafts amore means of descent or ascent are not provided, in sewer manholes, in gas or water wells, in empty oil tanks, and in sealed areas in mines. Heretofore, when such sampling was required, it was necessary to utilize the aspirating method, which was not always satisfactory; and to obtain samples of air in deep shafts, it was necessary to use long sections of rubber tubing, which was not always available. DESCRIPTION OF NEW DEVICE A new method or "device" employs a common snap-type mousetrap to break the neck of a vacuum tube at the place where it is desired to collect the sample (see fig. 1). A mousetrap is mounted on one end of a block of wood 11-3/4 by 3 by 3/4 inches in such camper that a lead weight attached to the trigger hall spring the trap when the device is given a sharp jerk. A vacuum tube is placed on the other end of the block and held in place by a strong rubber band. A strip of corrugated rubber is placed on each side of the grooved block to prevent the tube from clipping when the sample is taken. An adjustable shoulder, provided with a rubber cap, is pieced se that the neck of the vacuum tube will rest on it. The shoulder is made adjustable to accommodate various sizes of tubas and to keep the neck of the tube from breaking tee far back from the point. A metal handle is fastened to one end of the block, with a hole in the end through which the brass wire used for lowering the device is tied. The device is enclosed by a strong wire-gauge covering, hinged on one side and so arranged that it can be locked shut on the other side. This covering prevent: breaking of the tube while it is being lowered or raised in a shaft or other place. Brass wire of not less than 22 gage should be used for lowering the device. A detailed drawing of the device is shown in figure 2.

Jan 1, 1940

By T. E. Gray, A. W. Deurbrouck

This report describes the preparation characteristics of significant coalbeds in Kanawha County , W. Va . It is one in a series of Federal Bureau of Mines reports planned to determine coals suitable for producing metallurgical coke , either as mined or after beneficiation . Almost 9.4 million tons of coal was produced in Kanawha County , W. Va . , in 1959 , of which about 67 percent was cleaned mechanically in 10 cleaning plants . It has been estimated that more than 5,505 million tons remain in the county . Samples were collected from Pittsburgh , Stockton - Lewiston , Winifrede , Cedar Grove , Peerless , Upper Kittanning , Coalburg , Powellton , Eagle A , No. 2 Gas , and the Lower Kittanning beds . These beds were selected by the Bureau based on current production rates and estimated minable reserves . Float - and - sink tests of the samples collected from Eagle A , Peerless , Cedar Grove , Winifrede , and No. 2 Gas beds show that these coals at one location each are suitable for metallurgical use without washing . Lower Kittanning bed at four locations ; Pittsburgh , Stockton - Lewiston , and No. 2 Gas beds at two locations each ; and Coalburg , Powellton , Winifrede , Peerless , Upper Kittanning , and Cedar Grove beds at one location each can be upgraded to metallurgical quality by mechanical cleaning . Crushing the samples to 3/ 8- inch top size increased yields substantially at 1.30 specific gravity of Pittsburgh ( 17.5 percentage points ) and Upper Kittanning ( 13.0 percentage points ) beds and increased yield for the other beds sampled to a lesser amount . At this specific gravity , finer crushing caused In the 1.58 specific gravity float a general decrease in ash and sulfur . fractions of the other samples tested , most of the yields , and ash and sulfur contents , were lowered slightly by finer crushing .

Jan 1, 1963

By Irving Hartmann

Modern mechanized mining with high-speed machines, multiple-entry systems, multiple blasting, high-velocity air currents, and rapid haulage has brought many economic benefits and has on the whole enhanced safety in the coal-mining industry. It has, however, also introduced some added hazards, the control of which requires concerted effort and ingenuity. Mechanized mining has greatly increased the production and dissemination of fine coal seam or in mine entries. Use of high-speed machines has increased the probability of formation of incendive sparks, which are produced by frictional contact between moving metals and certain mineral substances in the coal seam or in the adjoining rock strata. In gassy seams rapid extraction of coal has increased the rate of gas evolution. These facts have made more urgent the need of preventing the ignition of coal dust and the development of widespread mine explosions. The ignition hazard can be controlled best by eliminating all potential igniting sources and by careful attention to ventilation designed to prevent accumulation of gas capable of triggering a coal-dust explosion. Frictional spark ignition by mining machines and suggested safeguards are discussed in a recent publication. Extensive research and long experience have shown conclusively that the propagation of coal-dust flames can be arrested and the development of widespread explosions prevented by properly applied, generalized rock dusting.

Jan 1, 1956

By M. G. Zabetakis

This publication presents a simplified graphic method for determining the explosibility of mine atmospheres under mine-fire conditions from mine- atmosphere composition data. Sometimes it is necessary to seal part of a mine during a fire to exclude air and thus extinguish the fire. Unfortunately, liberation of methane and formation of hydrogen and carbon monoxide in the sealed area may create an ex- plosive or flammable atmosphere if enough oxygen is present to support combustion. On the other hand, the oxygen concentration may be reduced through combustion processes and the concentration of inert gases (nitrogen and carbon dioxide) increased enough to render the atmosphere within the sealed area non-explosive. Before an area is unsealed, it is extremely important to know if the sealed atmosphere contains Flammable gases in proportions that might form explosive mixtures when air is introduced. If an explosive mixture forms and the fire is rekindled, a gas explosion will result. Various experimental methods may be used to determine the explosibility of a particular mine atmosphere; however, these methods usually are impracticable in the field.

Jan 1, 1959

By W. C. McBee

A family of modified-sulfur cements has been developed by the Bureau of Mines for the preparation of construction materials with improved properties. Various types of sulfur cements were prepared by reacting sulfur with mixtures of dicyclopentadiene (DCPD) and oligomers of cyclopentadiene (CPD). Durable cements were prepared with structural characteristics ranging from rigid to flexible. These cements were used to prepare corrosion-resistant materials for use in a wide variety of industrial applications where resistance to acidic and salt conditions is needed. These materials were prepared as rigid concretes, flexible pavings, spray coatings, and grouts. Production of modified-sulfur cements in a commercial-size plant was demonstrated.

Jan 1, 1981

By B. K. Cantrell, K. L. Rubow

"Quantifying exposure to diesel exhaust aerosol in an underground coal mine depends on the ability to measure this component of respirable mine aerosol separately from coal dust. Such measurement is complicated by the carbonaceous nature of both the diesel and coal dust particulate that make up the respirable aerosol. Hence, special sampling and analytical techniques must be used to distinguish between these two aerosol components.As part of a continuing study of diesel exhaust aerosol characteristics, the U.S. Bureau of Mines has applied size selective sampling together with gravimetric analysis to separate and measure respirable diesel exhaust and coal dust aerosol concentrations in diesel-equipped underground coal mines. This technique is based on the premise that the diesel portion of the aerosol is predominantly submicrometer and the mineral dust portion is mostly greater than 1 µm in size. In the study, chemical mass balance (CMB) modeling, based on the distribution of chemical elements in aerosol and aerosol source material samples, is used to referee the analysis of diesel exhaust and mineral dust aerosol concentrations from the size selective sampling results.Based on the results of the study, the Bureau, in cooperation with the University of Minnesota and the U.S. Mine Safety and Health Administration (MSHA), have developed a prototype personal diesel exhaust aerosol sampler for underground coal mines. The sampler has three stages: a preclassifier stage to select for respirable aerosol, an inertial impaction stage with an aerodynamic diameter(d) size cut at 0.8 µm to separate diesel aerosol from mineral dust and collect the mineral dust, and a final filtration stage to collect the diesel fraction of the sample. The sampler has been evaluated in both laboratory and field experiments conducted by the Bureau, MSHA, and the Generic Minerals Technology Center for Respirable Dust (GMTC-RD)."

Mar 1, 1992

By John Gross

"Introduction.Southern Illinois and Kentucky are credited with approximately 90% of the fluorspar production of the United States. A small amount of high-grade acid, spar is obtained from the ore by band sorting; the greater part, however, is recovered by jigs and tables as gravel spar containing approximately 85% calcium fluoride. In the jigging and tabling operations, galena is recovered, and enough silica and calcite are removed to raise the calcium fluoride content of the gravel spar to 85%. However, the removal of silica and calcite results in a large loss of spar. With increasing depth in the mines, zinc sulphide, sphalerite, is encountered in increasing quantity and the removal of this has become a serious problem. While the sphalerite can be fairly well removed from the spar by present milling methods, a marketable zinc concentrate can not be made. The experiments described below were made on fluorspar ore from Southern Illinois, by the mining experiment station of the U. S. Bureau of Mines, at Rolla, Mo., in cooperation with the Missouri School of Mines and Metallurgy.The ore tested contained. 7.3% lead, 27.9% zinc, 35.7% calcium fluoride, 9.5% silica and 4.7%. calcite.Tests and Results. In some preliminary tests it was noticed that a portion of the finely crushed ore adhered strongly to the sample pans, and upon investigation it was found that the adhering material was practically clean spar. By utilizing this property of adhesion 46.8% of the spar was recovered as a product containing 98.3% calcium fluoride. This suggested the possibility of using electrostatic separation."

Jul 1, 1921

By Donelson A. Robertson

Literature was searched and cases of alleged water well damage were investigated. Occurrence of ground water in Appalachia is primarily in low yield, fractured, water table aquifers. Four test sites were chosen based on geographic and geologic diversity. Test wells were drilled at each site and base line data on water quality, static water level, and drawdown characteristics were obtained before surface mining commenced. Blast induced ground vibrations were measured at the surface by the wells at levels up to 5.44 inches per second maximum resultant particle velocity. Measurements made at the bottom wells indicated that vibrations were considerably attenuated at depths of 140 to 160 feet. No direct evidence of change in water quality or well performance was produced by blast vibrations, but removal of downslope support by excavation does cause lateral stress relief which permits the water-bearing fractures to become more open. This additional storage capacity causes the static water level to drop and for well-bore permeability to improve. Static water level recovers if sufficient recharge is available and well performance is improved.

Jan 1, 1980

By William H. Pomroy

Fires in underground metal and nonmetal mines pose a threat to the safety of underground miners and to the productive capacity of this Nation&apos;s mines. Contaminated air (smoke, carbon monoxide, and other products of combustion) is the primary life safety hazard created by a mine fire. The most reliable defense against the hazard posed by the rapid spread of contaminated air underground is early warning fire detection and rapid evacuation. This Bureau of Mines report describes the design and operation of four prototype early warning fire detection systems, for underground noncoal mines, presently undergoing prolonged in-mine testing by the Bureau. The systems are described within the context of the underground mine environment.

Jan 1, 1985