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By John H. Scott

At the request of the Mine Safety and Health Administration, U.S. Department of Labor, the Bureau of Mines evaluated the model BT 300 C-D blasting machine tester, manufactured and distributed by Research Energy of Ohio, Inc. (REO), to determine whether the tester performed as stated by the manufacturer and responded satisfactorily to electrical faults introduced into the blasting machine circuit. Tester readings were recorded for 13 blasting machines and for 12 circuits constructed to simulate the electrical parameters of actual machines. The tester readings were acceptable for all of the blasting machines, although the switch position assigned to one machine produced an off-scale reading. The tester responded satisfactorily to the simulated circuits and detected serious voltage or capacitance faults when they were introduced. However, it did not respond accurately to certain resistance faults. Temperature tests were also made, and the tester performed equally well at temperatures of 20°, 42°, and 81° F. This tester was judged a useful accessory for field checking blasting machines for defective batteries and capacitors, despite its limitations. It is recommended that the tester manufacturer specify the lowest acceptable reading at which a blasting machine may be used and below which the blasting machine should be returned to the laboratory or manufacturer for maintenance.

Jan 1, 1981

By Charles L. Kimbell

The concept of data availability must be addressed, because there are perceptible changes from year to year, and the availability of accurately reported, precisely defined statistics and nonstatistical information provides the only sound basis for analytical studies required for government policy planning or industry market analysis. As the countries of Eastern Europe and the former U.S.S.R. undergo the transition from centrally planned economies to market economies, there has been a perceptible increase in information availability for rather obvious reasons. Any industrial operation seeking economic assistance from Government and/or private sources outside the country in which the facility is sited must provide some appraisal of its operations at the time it seeks assistance, as well as some information on previous performance to serve as tools in evaluating its potential under the proposed development scheme for which it seeks financial assistance. Additionally, there was growing governmental recognition that concealment of much of the national mineral production, trade, and consumption data for purposes of national military and/or economic security probably never was very successful, never was really necessary for most commodities, and certainly proved unnecessary with the end of the so-called cold war. Indeed, the long-term unwillingness to publish uniform statistical series of reliable,

Jan 1, 1993

By Charles W. Huggins

The Bureau of Mines investigated palygorskite, a natural asbestiform material, to accumulate knowledge that might serve as a foundation for future synthesis of a similar material. Unit cell, chemical analysis, DTA, TGA, optical constants, and electron microscopy data were obtained. Selected palygorskite samples of bettor than 97-percent purity were used to obtain this information. Chemical analysis revealed the following formula: (OH2)4 (OH)2 Ca0.01Fe0.02K0 .c3Mg2.10A12.00Si7.93020.3.91 H2O. The optical constants for sodium light are a = 1.522; S = 1.530; ?=1.533; biaxially (-). The following orthorhomibic unit cell constants were determined: ao = 12.690 A, Z = 2, bo = 17.857 A, Dx = 2.327. co = 5.207 A, Identical diffraction patterns resulted from the three palygorskite samples that were studied. X-ray, chemical, DTA, TGA, and optical data were compared with literature values for similar fibrous materials. X-ray diffraction lines were indexed. Several electron micrographs were made to compare the structures of palygorskite and attapulgite with that of chrysotile. The micrographs revealed extremely short laths for attapulgite, very long flexible laths for palygorskite, and tubular structure for chrysotile.

Jan 1, 1962

By Isaac A. Zlochower, Kenneth L. Cashdollar

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health conducted a study of the explosibility of various metals and other elemental dusts dispersed in air, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating the explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafhium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties - from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly "refractory" (very low volatility) elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechc ignitors. The experimental data obtained included the minimum explosible concentrations, maximum explosion pressures, and maximum explosion temperatures. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from -1 550 K for tin and tungsten powders to -2800 K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures. In general, the dusts whose experimental temperatures were closer to the adiabatic values were those with the finer particle sizes, those that were more easily vaporized, and/or those that were intrinsically more reactive.

By Henry D. Hibbard

The object of this report is to give briefly information of present value relating to the manufacture and uses of the various commercial alloy steels, with the hope of stimulating the demand for such steels and extending their practical use. The report is issued by the Bureau of Mines as a contribution to the increase of efficiency in the preparation and utilization of the mineral resources of the United States. Alloy steels are included in the so-called special steels, but as the latter term is often used in the mills to designate broadly any steels intended for purposes other than those served by the regular product, it has seemed best to use the more specific term of alloy steels in this report. Alloy steels are bringing about a series of revolutions in various in- dustrial fields in which steel plays an important part. Most elements that could be procured in sufficient quantity have been alloyed with iron in various proportions, either alone or in combination with others, in the search for useful alloy steels. Those steels that have gained and maintained for themselves a place in current use are discussed in this report. Some of them have had an ephemeral life of usefulness which would no doubt have been prolonged had not some other more satisfactory steel been developed. Probably the first useful alloy steel was Mushet's self-hardening tungsten tool steel, patented in 1868. Fifteen years later chromium steel, really containing chromium, was struggling for recognition for some purposes, the chief of which was for the manufacture of solid shot for piercing armor. In both of these steels the effect of the alloying element as used was in a way proportional to the amount contained. In 1882 Hadfield made his epoch-making discovery of manganese steel and demonstrated that in iron metallurgy it is not safe to take for granted anything as to the properties of an alloy of iron with other elements, basing one's opinion on past experience and knowledge, and that the effect of an alloying element may not be proportional to its content. The development of useful nickel

Jan 1, 1915

By Bruce T. Olenchuk, Wils L. Cooley

Electrical grounding is essential for the safe operation of power systems. A low-impedance path to ground is necessary to prevent the possibility of dangerously high potentials in human work areas. If for any reason this ground connection becomes faulty, a serious hazard may exist. One reason for faulty ground connections is ground bed corrosion. Corrosion of electrical ground rods has plagued the power industry and appeared in coal mine power systems. This paper will investigate ground rod corrosion, its cause, and possible solutions. Included is an evaluation of various ground rods for their ability to resist corrosion under stray current conditions. -The first known study of X-it3 Rod Corrosion is also presented.

Jan 1, 1979

By Clarence Hall, Spencer P. Howell

This bulletin deals with the characteristic features of the principal explosives used in mining and engineering operations, and espe- cially with the tests that show the suitability of different classes of explosives for different kinds of work. The Bureau of Mines pub- lishes the report as one of a series dealing with tests of explosives and methods of reducing the risks involved in the use of explosives in mining operations. The application of explosives to engineering and mining opera- tions has increased rapidly in recent years. According to a pre- liminary report issued by the Bureau of the Census, 469,000,000 pounds of explosives was manufactured in this country during the year 1909, and the greater part of this production was used for industrial purposes. In large engineering projects and in mining operations requiring the use of explosives the selection of a suitable explosive from the many varieties offered for sale is of fundamental importance. Vari- ous considerations are involved in the selection of an explosive of proper class for the blasting to be done. Many explosives suitable for quarry work are unsuitable for use in deep mines or in close workings. In metal mining and in driving tunnels the character of the gases evolved by the explosive on detonation is an important consideration. An explosive for use in gaseous or dusty coal mines must be formulated and compounded so that its flame temperature and the height and duration of its flame are reduced enough to per- mit its being used with comparative safety. In wet workings or in submarine blasting explosives impervious to moisture are requisite. In extremely cold climates explosives that do not require thawing are desirable, provided they are equally good in other respects. An essential requirement of all explosives, especially of those for use in tropical countries, is that they shall remain stable without change in chemical or physical characteristics.

Jan 1, 1913

By Michael J. Pazuchanics, Thomas J. Fisher, John J. Sammarco, Jeffrey H. Welsh

This report (An Introduction to Safety) is the first in a nine-part series of recommendations addressing the functional safety of processor-controlled mining equipment. It is part of a risk-based system safety process encompassing hardware, software, humans, and the operating environment for the equipment's life cycle. Figure 1 shows a safety framework containing these recommendations. The reports in this series address the various life cycle stages of inception, design, approval and certification, commissioning, operation, maintenance, and decommissioning. These recommendations were developed as a joint project between the National Institute for Occupational Safety and Health and the Mine Safety and Health Administration. They are intended for use by mining companies, original equipment manufacturers, and aftermarket suppliers to these mining companies. Users of these reports are expected to consider the set in total during the design cycle. • 1.0 Safety Introduction.—This is an introductory report for the general mining industry. It provides basic system/software safety concepts, discusses the need for mining to address the functional safety of programmable electronics, and includes the benefits of implementing a system/software safety program. • 2.1 System Safety and 2.2 Software Safety.—These reports draw heavily from International Electrotechnical Commission (IEC) standard 61508 and other recognized standards. The scope is "surface and underground safety mining systems employing embedded, networked, and non-networked programmable electronics." System safety seeks to design safety into all phases of the entire system. Software is a subsystem; thus, software safety is a part of the system's safety. • 3.0 Safety File.—This report contains the documentation that demonstrates the level of safety built into the system and identifies limitations for the system’s use and operation. In essence, it is a "proof of safety" that the system and its operation meets the appropriate level of safety for the intended application. It starts from the beginning of the design, is maintained during the full life cycle of the system, and provides administrative support for the safety program of the full system. [ ]

Jan 4, 2001

By Thomas J. Fisher, John J. Sammarco

This report (System Safety 2.1) is the second in a nine-part series of recommendations addressing the functional safety of processor-controlled mining equipment. It is part of a risk-based system safety process encompassing hardware, software, humans, and the operating environment for the equipment’s life cycle. Figure 1 shows a safety framework containing these recommendations. The reports in this series address the various life cycle stages of inception, design, approval and certification, commissioning, operation, maintenance, and decommissioning. These recommendations were developed as a joint project between the National Institute for Occupational Safety and Health and the Mine Safety and Health Administration. They are intended for use by mining companies, original equipment manufacturers, and aftermarket suppliers to these mining companies. Users of these reports are expected to consider the set in total during the design cycle. • 1.0 Safety Introduction.—This is an introductory report for the general mining industry. It provides basic system/software safety concepts, discusses the need for mining to address the functional safety of programmable electronics, and includes the benefits of implementing a system/software safety program. • 2.1 System Safety and 2.2 Software Safety.—These reports draw heavily from International Electrotechnical Commission (IEC) standard 61508 [IEC 1998a,b,c,d,e,f,g] and other recognized standards. The scope is “surface and underground safety mining systems employing embedded, networked, and nonnetworked programmable electronics.” System safety seeks to design safety into all phases of the entire system. Software is a subsystem; thus, software safety is a part of the system’s safety. • 3.0 Safety File.—This report contains the documentation that demonstrates the level of safety built into the system and identifies limitations for the system’s use and operation. In essence, it is a “proof of safety” that the system and its operation meet the appropriate level of safety for the intended application. It starts from the beginning of the design, is maintained during the full lifecycle of the system, and provides administrative support for the safety program of the full system.

Jan 4, 2001

By Seth C. Schaefer

[As part of the Bureau of Mines effort to provide thermodynamic data for advancement of mineral resources technology, the standard Gibbs energies of formation (?G°f) of MnS (manganese sulfide) and Fe0.9 S (pyrrhotite) were investigated with a high-temperature galvanic cell employing stabilized Zr02 (zirconia) as the electrolyte. Potential measurements were obtained for the cell Pt, MnS, MnO, S02 (g, 1 atm)//Zr02//02(g, 0.0114 atm), Pt with the overall cell reaction MnS (s) + 1.5 02 (g, 0.0114 atm) = MnO (s) + S02 (g) . (1) These results give the standard Gibbs energy of formation of MnS for the reaction Mn (s) + 0.552 (g) = MnS (s) (2) ?G°f = -66.487 + 15.19 x 10-3T±0.207 kcal/mole (896.4 - 1,208.1 K) (3) where temperature (T) is expressed in kelvins. Similar measurements were obtained for the cell Pt, FeO .9S, Fe304 , S02 (g, 1 atm) //Zr02//02 (g, 0.0114 atm) , Pt with the overall cell reaction 10/3 FeO .9 S (s) + 16/3 02 (g, 0.0114 atm) = Fe.,04 (s) +10/3 S02 (g). (4) These results yield the standard Gibbs energy of formation for the reaction 0.9 Fe (s) + 0.5 S2 (g) = Fe0.9 S (s) (5) ?G°f = -35.229 + 12.67 x 1073T+-0.104 kcal/mole (839.5 - 1,086.6 K). (6) A third-law analysis of MnS data yields a standard enthalpy of formation (AH°f) for the reaction Mn (s) + S (rh) = MnS (s) (7) ?H°f298 = -51.16±0.21 kcal/mole (8) A similar third-law analysis for Fe0.9S data yields a ?29°f298 for the reaction 0.9 Fe(s) + S(rh) = FeO .9S(s) (9) ?HO\°f298 = -24.01±_0.15 kcal/mole. (10) ]

Jan 1, 1980

By Kevin Connor

During 1984, minerals exploited in Burundi included gold, kaolin, lime, and peat. Over 1,100 troy ounces of gold was extracted and traded during the year as a result of the lifting of the Government ban on gold mining in mid-1983 and the establishment of an artisan mining program and licensed trading counters. Almost 2,000 tons of kaolin was mined for the manufacture of insecticides. Lime production was for domestic fertilizer applications. Amoco International and the Government signed an accord late in the year for a petroleum exploration program covering 600,000 acres of Burundi's onshore Ruzizi Plain and part of northeastern Lake Tanganyika. Amoco was expected to begin the exploration program by mid-1985. Anticipated program costs could run as high as $200 million.2 The Finnish company Ekono Oy completed its peat industrial energy development studies for the Buyongwe peat deposits of northern Burundi by the end of the year. The project assessed the quantity and fuel quality of 13,000 hectares of peatland and was part of a larger study for developing the Musangati lateritic nickel deposits of Burundi, estimated at 3% of the world's reserves of nickel. The Buyongwe peat would fuel dryers and an electrical generating plant for supplying power to nickel ore processing facilities. Briquetted peat would also be used as a substitute for wood and charcoal, presently the main sources of rural energy in the country and rapidly depleting because of deforestation. The study also evaluated the most economical methods to harvest the peat bogs. The study was financed by the International Development Association (IDA), United Nations Development Program (UNDP), Finnish Aid-Finnida, and the Burundi Government.

Jan 1, 1986

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

Computer input data for an operating mine is developed on the basis of a detailed ventilation survey which includes air quantity, air quality, pressure loss and fan performance measurements. Quantity measurements must be reviewed extensively and assumptions made about leakage quantities and airflow paths. Pressure measurements must be reviewed and developed into a pressure gradient for the mine system. Air quality measurements are used to determine methane sources and amounts. Finally, the fan test data is used to develop the correct fan characteristic curve. Quantities and pressure losses for each branch in the system are used to calculate the branch resistances which are then utilized in the ventilation simulator to model the mine system. QUANTITY BALANCE The quantity of air coming into a mine based on field measurements will rarely equal the quantity exiting the mine, even if allowances are made for methane or compressed air input to the system. The same statement can be made for airflow through any isolated part of the mine ventilation system such as individual working section or main aircourses leading to an area isolated from the rest of the mine. The reason for the apparent discrepancies is the accuracy of the indicated quantities which in turn is based on the accuracy of the individual velocity and area measurements. Even with measurements following the guidelines described in the previous section on quantity measurement, this error can only be minimized but not eliminated. As a result the ventilation system must be carefully balanced so that, for any loop, the quantity in plus any methane or compressed air injection will equal the quantity out. The continuity of flow described by the balanced system must approximate the

Jan 1, 1977

By R. V. Ramani, V. T. Burgos, J. A. McClay

The data for Test I1 describes an underground bituminous coal mine operating in a 72 inch seam, with an estimated production rate of 4,257,000 tons per year. The system includes 15 continuous mining sections, conveyor belt haulage, and a rail network for supply and personnel transportation. The following section includes the input data sequence, annual cost report, and cash flow analysis "report for this data set.

Jan 1, 1975

By R. V. Ramani, C. B. Manula, A. Owili-Eger

Recently, a collection of programs that will simulate a ventila¬tion system with extensive analyses and report-generating capabilities and error diagnostics has been developed (Didyk, 1974). It has pro¬visions to handle air injections, methane or gas emissions, and leakage. Additionally, it will solve problems where fixed and/or maximum air quantities are specified for some airways. Finally, the simulator has been structured to be extremely modular so that additions and revisions to the model can be easily made. The general aspects of the information flow and logical structure of the mine ventilation simulator are shown in Figure 14. The output from the methane emission model is input into the ventilation simulator for calculation of the concentrations in all branches of the network. The methane model and the ventilation simulator provide powerful tools for the analysis and planning of mine ventilation systems. INPUT DATA REQUIREMENTS In all of the mathematical models, several coefficients that de¬fine the characteristics of the ventilation system are used. For the ventilation simulator, these include the frictional characteristics of the ventilation regulatory devices. Considerable work has been done on the experimental determination of these coefficients for smooth pipes and well-defined mediums, but only limited data are available for actual mining conditions. FRICTION FACTORS: The frictional characteristics of mine airways affect both the dispersion of pollutants and air flow through the roadways,. They

Jan 1, 1975

By Robert F. Chaiken, Thomas H. Dubaniewicz, Gregory M. Green, Kenneth L. Cashdollar

Optical technologies have progressed rapidly in the past 15 years. One application of laser technology in underground coal mines currently under evaluation is the remote measurement of explosive methane gas. Federal regulations require that atmospheric monitoring systems used in gassy underground mines where permissible equipment is required shall be intrinsically safe. Mine Safety and Health Administration criteria for the evaluation and testing of intrinsically safe apparatus and associated apparatus contain no specific guidance for optoelectronic components such as diode lasers. The National Institute for Occupational Safety and Health is conducting a study to help provide a scientific basis for developing appropriate safety guidelines for optical equipment in under- ground coal mines. Results of experiments involving ignition of methane-air mixtures by collections of small heated particles of Pittsburgh seam coal and black iron oxide are reported. The inert but more strongly absorbing iron oxide targets consistently ignited methane-air mixtures at lower powers than the coal targets. Minimum observed igniting powers for laser energy delivered by 200, 400 and 800 pm core fiber optic cables and directed onto iron oxide targets in methane-air atmospheres were 0.6, 1.1, and 2.2 W, respectively. Comparisons with the results of other researchers are made. A thermal layer theoretical approach to describing the process is included as an appendix.

By Dennis R. Dolinar, Eric R. Bauer

Skin failures of roof and rib in underground coal mines continue to be a significant safety hazard for mineworkers. Skin failures do not usually involve failure of the support systems, but result from rock or coal spalling from between the support elements. For instance, in 1997 more than 800 miners were injured by roof and rib falls, of which 98% were the result of skin failures [Bauer et al. 1999]. Also, nearly 80% of the roof and rib failure injuries occurred at or near the working faces in development sections. The face area is a zone where the potential for skin failure accidents and injuries and for roof and rib failures is high because of mining activity, ground readjustment due to changing stress conditions, and the higher exposure of mine workers. In addition, failures occur where the roof and rib are unsupported. This paper reviews the roof and rib accident statistics resulting from skin failure, and highlights the incidences by type, numbers and percentage, in-mine location, supported and unsupported roof, and worker activity at the time of injury. Also discussed are the causes of roof and rib skin failures, current and improved support methods and materials for skin surface control, and machine design modifications for improved roof bolter operator protection. It also reviews the historical literature on skin failures and control methods.

Jan 10, 2000

By Oliver Bowles, J. E. Crawshow

A line of cordeau detonating fuse was placed in hole No. 2, no electric detonators being used in the hole. After 12 or 13 cases of 40 per cent nitro starch powder had been poured into the hole in loose form, it was found that a space of only 17 ft. remained for stemming. It was decided that space for an additional case of powder might be obtained by tamping the charge. The tamping was done with a heavy plunger, about 3 or 3 inches in diameter and 10 inches long, made of lead with an iron core with an iron eye in the top to which a 3/4 inch rope was attached, and weighing between 30 and 40 pounds. This weight was intended for use in sinking explosive in wet holes, and not for tamping. It is estimated that the tamping had continued at least 10 The quarry superintendent had gone a considerable distance for a box of powder, returned, and reached a point about 10 feet from the hole, minutes.

May 1, 1920

By Frank D. Lamb

Pyrophyllite, a hydrous aluminum silicate (Al2 Si4O10 (OH)2 ) has been mined in North Carolina and marketed without beneficiation for the past 100 years, but recent demands for higher-grade material indicate that an economical concentration method is needed for at least a part of the pyrophyllite production. Past production has depended upon selective mining and hand sorting, which is often unsatisfactory because of the finely disseminated character of the ores. The major impurity in North Carolina pyrophyllite ores is quartz, which accounts for the abrasiveness of the commercial product. Since pyrophyllite is only slightly heavier than quartz, those ores cannot be beneficiated by simple gravity-concentration methods. Some separation can be attained by differential grinding and air classification because of the difference in hardness of the two minerals) but the separation is not sharp. Froth flotation of pyrophyllite from Quartz has never been attempted commercially, but if the demand for high-grade material is sufficient, it would seem that this process offers the most premise of being economically feasible.

Jan 1, 1950

By S. J. Schatzel

In an effort to increase productivity, many longwall mining operations in the U.S. have continually increased face lengths. Unfortunately, the mining of larger panels may increase methane emissions. The National Institute for Occupational Safety and Health (NIOSH) conducted a mine safety research study to characterize and quantify the methane emissions resulting from increasing face lengths in the Pittsburgh Coal-bed. The goal of this research effort was to provide the mine operator with a method to predict the increase in methane emissions from the longer faces for incorporation of additional methane control capacity into the mine planning process, if necessary. Based on measured methane emission rates of 0.066 m3/s (140 cfm) for a 315 m (1032 ft) face, projected longwall face methane emission rates were 0.090 m3/s (191 cfm) for a 366 m (1200 ft) face, 0.106 m3/s (225 cfm) for a 426 m (1400 ft) face, and 0.124 m3/s (263 cfm) 488 m (1600 ft) face.

Jan 1, 2006

By J. P. Rider

Average production from longwall mining operations in the United States has risen from approximately 800 tons per shift in 1980 to over 4,600 metric tons per shift in 1999. Such a large increase in production has the potential to generate significantly more dust. Previous NIOSH research has shown that, on average, respirable dust levels generated by the shearer accounts for 50% of the airborne dust generated during longwall mining. Ventilating air and water are primary controls being used in an effort to reduce longwall dust levels. Longwall operators are applying more air and water than ever before and have expressed concern over reaching maximum practical limits for these controls. Full-scale laboratory tests are being conducted to evaluate the impact on shearer-generated dust levels for changes in face air velocity, water quantity at the shearer, water spray pressure, spray system design, mining height and cutting direction. Results of this research should identify the most appropriate control levels for various operating conditions. In addition, general recommended dust control practices for longwall mining will be discussed. KEYWORDS Longwall, coal dust

Apr 1, 1975