Search Documents

By Steven J. Page, William A. Heitbrink, Andrew B. Cecala, Edward D. Thimons, John A. Organiscak

Miners at noncoal surface mining operations are often exposed to high levels of respirable dust. In an effort to lower the respirable dust exposure of these surface miners, the National Institute for Occupational Safety and Health (NIOSH) has been conducting research to address this problem in a practical and economically viable manner. One successful effort deals with lowering the dust exposure of equipment operators in enclosed cabs. Many types of surface mining equipment utilize enclosed cabs to protect equipment operators from dust exposure. Normally when the equipment is new, the cabs are fairly airtight. These tightly sealed cabs, combined with good filtration systems, generally provide the operator with good dust protection. However, most mining equipment is older, and as aging occurs, many components of the enclosure deteriorate. The structural integrity of the cab diminishes and the effectiveness of the air filtration system fails. NIOSH has been successfully researching costs-effective methods to improve both filtration effectiveness and cab integrity of these older cabs in order to provide a healthier work environment for equipment operators. Dust sampling records indicate that drill operators and helpers have the highest dust exposure of all workers at surface mining operations. Since much of the overburden contains a high percentage of silica, the health hazard associated with this dust can be even more serious. NIOSH research is addressing techniques to lower respirable dust levels at surface drilling operations. INTRODUCTION NIOSH's mission is to assure a safe and healthy work environment for the working men and women of this nation. The primary emphasis of NIOSH's Pittsburgh Research Laboratory (PRL) is mining health and safety research. This report focuses on two areas of research

By J. B. Littlefield

This study is one of a number conducted to determine the concentration of dust in the air during the complete cycle of operation in wet drilling information as to various factors connected with drilling in mining operations is considered to be of definite value in the control and prevention of air dustiness, and it is particularly desirable to ascertain What features of present-day wet-drilling operations in mine work contribute to dust disease and to remedy deficiencies when they are found. ACKNOWLEDGMENTS A testing alit through rock strata is being developed by the Mining Division of the United States bureau of Mines at Mount Weather, Va., and the tests discussed in this report were conducted there. This experimental alit in rock, constitutes a typo of laboratory where mine conditions can be closely simulated and where many of the variables likely to occur in an actual mine can be eliminated or at least controlled with reasonable effort, thus affording maximum opportunities to secure fundamental data uncomplicated by extraneous conditions. The authors wish to acknowledge the valuable assistance and cooperation of several members of the Mining Division, particularly C. F. Jackson, chief engineer, McHenry Mosier, associate mining engineer, and G. E. McElroy, supervising engineer, mine ventilation.

Jan 1, 1938

By D. G. Kesterke

Research was conducted to determine the feasibility of extracting elemental oxygen from silicate-bearing melts by high-temperature electrolysis. The method was based on a modification of existing processes for electrowinning metals from their oxides dissolved in molten halide systems. Electrolyses were performed at temperatures ranging from 1,050° to 1,250° C in boron nitride cells that incorporated a silicon carbide cathode and an iridium anode. The electrolytes contained volcanic scoria as the oxygen source, plus mixtures of BaF2 and LiF as fluxing agents. Cell gases containing almost 14 volume-percent oxygen were obtained. The average anode current efficiency for several experiments of extended duration was calculated to be 55 percent. Cell design and operating conditions are described, and some of the problems associated with the process are discussed.

Jan 1, 1971

Identity the difficulties of establishing vegetation on mining-related wastes resulting from adverse chemical, physical, and biological properties; describe the ecological and soil factors affecting the relationship between mycorrhizal fungi (soil microorganisms) and plants; and evaluate the feasibility of establishing vegetation on mine waste by introducing mycorrhizae. Problems in Revegetation Successfully using vegetation to stabilize a situ disturbed by mining-related activities depends on knowing the chemical, physical, and biological characteristics of the site prior to, or at the time of, stabilization. The primary objectives of mine land reclamation are to minimize environmental degradation and to facilitate the re-establishment of a functional plant-soil system. Mining disturbances can significantly alter the physical, chem¬ical, and biological characteristic of a site, thus affecting plant establishment, survival, and growth. The physical disturbance caused by the removal and replacement of soil and overburden, together with the waste material from ore processing, affect the chemical, physical, and biological process within the disturbed soil or waste. Additionally, variability in soil properties results from differences in climate, topography, vegetation, and parent material of the site.

Jan 1, 1993

Reduce methane levels around the shearer machine during longwall mining by directing more of the available airflow along the face and over the shearer body. Approach To address the entire mining cycle, two techniques were combined to dilute and clear the methane liberated from the face by the shearer during cutting. The first is the modified shearer clearer system, which is used during the entire face pass. This is combined with the walkway curtain which is used only during the headgate cutout. How It Works Methane ignitions are one of the most potentially serious hazards facing longwall mine operators. The high rate of coal extraction on longwall sections can liberate a significant quantity of methane during a pass. The modified shearer clearer is used to dilute methane concentrations along the entire face for both cut directions. The shearer clearer system, originally designed as a dust control technique, uses a series of water sprays located on the shearer body to direct more airflow along the face and over the shearer. (See Technology News issues, #112, #118, and #221). The only change from the original shearer clearer design is the addition of three sprays to the return-side splitter-arm/ shearer interface. The additional sprays help to ventilate the area behind the shearer body.

Jan 1, 1985

By Ted C. Briggs

Equations for the elastic pressure distortion of the volumes of a Burnett compressibility apparatus are developed and presented in this report for volumes under internal and external applied pressures. An experimental method for the determination of the external pressure distortion coefficients is presented. Young?s modulus and the internal-pressure distortion coefficients are computed from the experimentally determined external-pressure distortion coefficients. The temperature dependence of the pressure distortion coefficients and of Young's modulus is evaluated for the temperature range 0° to 80° C.

Jan 1, 1968

By Gerald J. Joy, Paul J. Middendorf

This study examines the patterns and trends in noise exposure documented in data collected by Mine Safety and Health Administration inspectors at U.S. coal mines from 1987 through 2004. During this period, MSHA issued a new regulation on occupational noise exposure that changed the regulatory requirements and enforcement policies. The data were examined to identify potential impacts from these changes. The overall annual median noise dose declined 67% for surface coal mining and 24% for underground coal mining, and the reduction in each group accelerated after promulgation of the new noise rule. However, not all mining occupations experienced a decrease. The exposure reduction was accompanied by an increase of shift length as represented by dosimeter sample duration. For coal miners exposed above the permissible exposure level, use of hearing protection devices increased from 61% to 89% during this period. Participation of miners exposed at or above the action level in hearing conservation programs rapidly reached 86% following the effective date of the noise rule. Based on inspection data, the occupational noise regulation appears to be having a strong positive impact on hearing conservation by reducing exposures and increasing the use of hearing protection devices and medical surveillance. However the increase in shift duration and resulting reduction in recovery time may mitigate the gains somewhat.

By C. M. Frost

The hydrodesulfurization characteristics of a Venezuelan topped crude oil and a Venezuelan reduced crude oil were determined at temperatures from 740° to 850° F, pressures from 800 to 1,600 psig, and space velocities from 1.0 to 2.0 Vo/Vc/hr. Kinetic calculations showed that under these conditions the desulfurization reaction was first order with respect to sulfur and had an average activation energy of 32.5 kcal/mo1. Catalyst life tests made at 750° F, with pressures of 800, 1,200, and 1,600 psig and space velocities of 1.0 and 1.25 Vo/Ve/hr, showed that the decrease in the relative activity of the catalyst was a logarithmic function of time or volume of oil processed and the amount of vanadium deposited on the catalyst. Comparative tests made with residual fuels prepared from a Wilmington, Calif., crude oil and a Wyoming asphaltic crude oil showed that catalyst life may be extended by processing fuel oil with a low metal content, but it may be shortened by the presence of large amounts of asphalt in the feed.

Jan 1, 1971

By M. Howard Berliner

"INTRODUCTION During the last 4 months of 1943, the Bureau of Mines engaged in an investigation and exploratory drilling program in the area between the Coughlin and Galena Level mines near the town of Shullsburg, in Lafayette County, Wisconsin. The work was undertaken as part of a general Bureau of Mines investigation of the zinc-producing area of southwestern Wiscon¬sin at a time when an effort was being made to increase the production of metals important to the Nation's war program.The portion of the southwest Wisconsin zinc district in the immediate vicinity of Shullsburg and the Coughlin and Galena Level mines is well mineralized. The principal ore horizon is at shallow depth, and there is evidence that relatively extensive surface mining for lead was done over a period of many years. Underground mining' for lead and zinc has continued to the present time.The Bureau undertook an exploratory drilling program in the area immediately west and southwest of the Coughlin mine workings after thorough preliminary investigations and geologic studies indicated that such work would serve to guide operators in the development of new ore reserves needed for continuance of mining operations in that area."

Apr 1, 1947

By Martin Hertzberg

In this Bureau of Mines report, the optical detection of fires and explosions is considered fundamentally. The measured spectral radiances from methane-air ignitions are compared with the background irradiances from stray and ambient sources, and with the spectral sensitivites of various sensors. The comparison naturally suggests the optimum spectral ranges and signal processing logic that can uniquely characterize the ignition event. Both ultraviolet (UV) and infrared (IR) are considered. Several alternate sensing methods are proposed and discussed. The development and testing of an IR system designed for use in ignition suppression devices in mines is described.

Jan 1, 1975

By M. R. Geer

The washability examination of a coal establishes the quality of the product that could be prepared by mechanical cleaning, shows how much impurity would have to be eliminated to attain a particular quality of product, indicates what type of cleaning process would be suitable, and tells whether the coal could be cleaned efficiently, The coal-preparation laboratories of the Bureau of Mines make washability examinations of coal for a variety of purposes. Sometimes these examinations are made as an integral part of research conducted on coal-washing problems. Occasionally they are made on coals mined on Government-owned land or on coals destined for use in Government installations. Often they are made on coals from new fields or new beds in existing fields to help establish the characteristics of the Nation's coal reserves. Whatever the original reason for doing the work, the results often are useful later in evaluating deposits or in the design of cleaning plants. Publication of the results of such studies provides for the widest possible usefulness. This report brings together the results of washability examinations made on 1 coal each from Oregon and Idaho, 2 from Wyoming, 5 from Utah, and 11 from Washington. Material of this nature is inherently difficult to summarize. Some of the coals are so clean} despite full-scam mechanical mining, that they could not be improved materially by washing; others present some of the most difficult preparation problems found in the country.

Jan 1, 1961

By Wing G. Agnew, John A. Johnson, McHenry Mosier

"INTRODUCTION AND CONCLUSIONSThe first three reports of investigations 5/ in this series, pertaining to the investigation of stemming at the Mount Weather Testing Adit dealt with the dust produced by blasting, the effect of stemming on gases generated by blasting, and the relative advantages and disadvantages of different types of stemming and no stemming when used with 60-percent ammonia gelatin dynamite.This report covers an investigation of the length of stemming material through which a primer will fire and detonate a charge of dynamite, such as a missed hole.The practice of drilling a new hole a foot from a missed hole to blast out the missed hole should be prohibited. It is dangerous, as is evidenced by the number of miners killed through drilling into missed holes. It is even more hazardous in a mine on a multiple-shift basis, in which the same miners do not drill succeeding rounds."

May 1, 1942

By Robert L. Lagace

The attention of this group was focussed on four through-the-earth communication systems that are presently of high interest to the U.S. Bureau of Mines; four systems for providing operational/emergency communications on the working sections of coal mines, indeed up to the very face of the section. The systems are: uplink-data, downlink-voice, sidelink-call alert coded page, sidelink-roof bolt voice page. Each of these systems makes use of the mine overburden as the signal transmission medium, as opposed to the guiding wires, cables, and tunnels treated by the operational communications working group. Each of these systems satisfies one or more of the Bureau's objectives for mine communications systems; namely • reliable links for monitoring the mine environment under both operational and emergency conditions. • reliable links for communicating with miners during emergencies. • special links for increasing the efficiency of day-to-day operations of the mine. Each of these systems has been successfully demonstrated on a limited experimental basis, and prototypes of all these systems are installed and operating in the USBM experimental mine in Bruceton, Pa. Each of these systems must now be optimized regarding its performance, and engineered for practical routine application to the working sections of actual operating coal mines, particularly those of the room and pillar type. This optimization and engineering must take place subject to the principal constraints listed by Howard E. Parkinson in his Workshop paper entitled, "Objectives and Constraints of Through-the-Earth Electromagnetic Communications Systems'' and enumerated below. • Depth of Mine Overburden • Overburden Conductivity • Electromagnetic Noise In and Above Mines • Limited In-Mine Electrical Energy (Stationary or Man Carried) During an Emergency • Intrinsic Safety for In-Mine Equipment • Practical and Rugged Equipment for Use Under Both operational/Emergency conditions • Severe Weight Limitations for Man Carried Equipment • Reasonably Low Costs Especially for Man Carried Equipment Part II of this paper provides a brief description of each system, while Part III summarizes the present status of developments related to these systems and some recommendations for future work needed to advance these systems to the practical application stage.

Jan 1, 1973

By N. F. Le Jeuns

For a number of years the Bureau of Mines has conducted semi-annual surveys to determine the changes in motor gasoline being sold in the United States. It was pointed out in the previous survey that there was an apparent tendency toward greater uniformity in the character of gasoline marketed in the United States. This practically uniform tendency which continued from April, 1917 to January, 1923, has been interrupted in the, present survey, as shown by an examination of the column marked "Difference," as given in Table 1. The figures in this table were obtained by averaging the end points of the least volatile and most volatile samples of gasoline. For example, of 850 samples analyzed in 1919, the 10% ,(85 samples) having the highest end points and the 10% having the lowest end points mere grouped, and the end points of each group averaged. These averages are represented in the table as the "Maximum 10%" and the ?Minimum 10%? respectively. The same process was used on the other surveys.

Jan 1, 1923

By D. W. Frommer

Laboratory mineral-dressing investigations were conducted on talc-bearing samples from Arkansas and Texas under the Bureau of Mines program of examinations and surveys, which is concerned, in part, with the improvement of conservation and utilization of domestic mineral resources. Two of the soapstones in question were successfully upgraded by flotation, utilizing stage additions of a frother and an amine to promote their talc content. The process could enable the producers to meet more rigid specifications of higher priced talc commodities. INTRODUCTION Talc is an industrial mineral with distinctive properties, such as softness, smoothness, large surface area in relation to mass, chemical inertness, and good retention as a filler, that make it particularly valuable to a number of industries. Sales to 6 industries -ceramics, paint, insecticide, rubber, roofing, and paper -consumed 84 percent of the domestic production of talc, pyrophyllite, and ground soapstone in 1952. Mine production in that year totaled 600,908 tons. Sales of crude and ground material were 593,147 tons valued at $11,347,317.2/

Jan 1, 1956

Provide an economic alternative to drill-blast excavation with the same ability to excavate openings of varied orientation, shape, and size. Approach Develop an efficient, adaptable, mechanical excavation machine that produces unconfined tensile failure in rock. How It Works A drill-split fragmentation machine that combines a drill and a unique splitter has been developed. The drill and splitter are mounted on a carriage that positions the splitter in a hole immediately after it is made by the drill. The splitter creates force loads that cause the rock to fragment, and the process is repeated for excavation. The unique splitter applies both radial and axial loads to the rock mass, which produces an excavation action comparable to pulling a plug. This excavation action distinguishes the radial-axial splitter from typical demolition splitters, which require a free surface parallel to the axis of the splitter toward which to break rock.

Jan 1, 1989

By Jennifer A. Slatnick

The U.S. Bureau of Mines estimated the potential availability of titanium from 39 mines and deposits in 12 market economy countries. The evaluated properties account for 76 pet of the market economy country demonstrated resources, which total 603 Mt of contained titanium dioxide (Ti02) in the minerals rutile, ilmenite, leucoxene, and anatase, and represent 95 pct of current production. Approximately 250 Mt of contained Ti02 could be economically recovered from evaluated titanium operations at January 1992 market prices. In terms of mineral concentrates, this equals approximately 19 Mt of rutile concentrate, 110 Mt of ilmenite concentrate, 47 Mt of synthetic rutile concentrate (in addition to the ilmenite), and 160 Mt of titanium slag that could be recovered. Over the past decade, the titanium minerals industry has adapted to the changing market. In the 1980's, titanium producers expanded production because of the rising demand for titanium products. Today, the titanium industry is in a state of overcapacity, and byproduct revenues, such as that from zircon, have become essential in keeping operations profitable. The industry has also witnessed a greater dependence on upgraded ilmenite products, such as titanium slag and synthetic rutile, because of the expense of rutile and the lower wastes emitted from these upgraded products. As a result of this dependence on upgraded ilmenite products, South Africa has become a leading titanium producing country and has displaced Australian production.

Jan 1, 1994

By A. H. Warner

Sphalerite crystals occur sparingly in minor faults and pockets in a coarsely crystalline dolomite on the Brown-Tipton farm near Greenville in Greene County, Tenn. After several visits by U. S. Bureau of Mines engineers and U.S. Geological Survey geologists, a survey was r: the in the fall of 1944. Upon their recommendations, trenches on the Brown farm under Bureau of Mines supervision. In each case, the bed most favorable for zinc deposition was exposed. In the finished trench bottoms no zinc minerals are visible.

Jan 1, 1950

By J. E. Pahlman

One of the goals of the Bureau of Mines is to develop metallurgical pro-cesses that conserve energy and/or that take advantage of abundant domestic energy sources. Western lignites and subbituminous coals can be used for firing pellet induration and metallization furnaces. However, the refractory linings of these furnaces must be able to withstand attack from corrosive alkali metal oxides present in the ash of many of the low-rank fossil fuels. The Bureau of Mines conducted dynamic and static slag tests on high-alumina and alumina-silica refractories to determine their resistance to lignite ash slags. The investigations showed that increased alkali content in the lignite ash caused increased corrosion and erosion of the tested refractories. The degree of corrosion decreased with increasing alumina content, with the 99-percent-alumina refractories having the highest resistance. In general, the matrix phase was attacked preferentially to the alumina grains. Also, porosity reduction and tar impregnation enhanced the corrosion and erosion resistance. The 90-to 99-percent-alumina refractories are recommended for use as furnace linings in alkali slag environments.

Jan 1, 1979

By Francis R. Redfern

Newton's method of solving a nonlinear equation is employed to develop a least-squares acoustic emission source location method in which the spatial residuals of the location equations are minimized. These residuals, related to the distances from the least-squares source location perpendicular to the surfaces described by the location equations, permit location error to be estimated to first order along the spatial axes. The solutions obtained by this method are the best spatial solutions to the location equations in the least-squares sense. Also presented is a procedure by which the geometrical control of a transducer array can be evaluated using the rate of change of source location with fractional velocity change.

Jan 1, 1982