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By H. B. Humphrey, J. J. Forbes

"In accident prevention, a study of statistical data is necessary to determine primary causes of accidents to devise means to eliminate causes at the original sources. Explosions in coal mines of the United States during the 10 years ending December 31, 1931, ranked third in the causes of fatal accidents; they constituted 16.2 per cent of all fatal accidents in bituminous mines and 8.4 per cent of all fatal accidents in anthracite mines. A study of coal-mine explosions in Pennsylvania, with approximately 160,000 men employed in anthracite mines and about 145,000 in bituminous mines or about 205,000 out of -the approximately 525,000 men employed in all coal mines of the United States, should give information of value to all persons endeavoring to reduce or eliminate coal-mine explosions. This circular reviews explosions of gas or dust or of both in the coal mines of Pennsylvania to show the hazard of gas and dust, to point out the influence of certain factors in causing explosions, and to emphasize the efficacy of explosion-preventive measures.The data published annually by the State Department of Mines and of the United States Bureau of Mines were used in compiling the tables of explosions. Through the cooperation of W. H. Glasgow, secretary, Department of Mines of Pennsylvania, and his assistants, many doubtful cases were clarified, so that as far as recorded the history is comparatively complete. Figures used in compiling some of the tables were furnished by W. W. Adams, chief statistician, demographical division, United States Bureau of Mines.Anthracite in the Wyoming Basin of Pennsylvania was used locally by gunsmiths in 1755, by blacksmiths in 1769, and as domestic fuel in 1808.Mining and shipments developed slowly between 1806 and 1812, but more rapidly after that.Early mining along the outcrops gave essentially no trouble from gas, but by 1870, when State inspection was established, explosions were frequent; ventilation was crude and accumulations of gas were generally ""brushed"" or burned out.Table 1 lists 1,232 ignitions and explosions of gas in anthracite mines from 1870 to 1932, inclusive, every one of which was accompanied by loss of life. Some details are given of 110 representative cases in which five or more lives were lost or in which it appeared that some violence was present.During the period 1870 to 1932, inclusive, gas explosions caused 2,213 fatalities, or an average of about two deaths for each ignition or explosion. Records are not available as to the number injured in these and in other explosions where no deaths occurred, but from a study of explosion reports it appears probable that the number injured exceeds the number killed. In the 110 cases described, 599 were killed and 294 were injured. As shown in Table 2, fatalities from gas explosions averaged 8.3 percent of the total fatalities in Pennsylvania anthracite mines from 1870 to 1931, varying from 6.0 percent in 1931 to 13.1 percent in 1927."

May 1, 1933

Provide a means of evaluating the in place structural properties of coal seams and coal measure rocks in advance of mining. Approach Develop a sonic logging probe for use in dry wells, a condition common to shallow wells and semi-arid coal regions. How It Works The Bureaus' sonic probe differs from conventional sonic probes because it does not require fluid in the well to couple sonic vibrations to the drill hole wall. A self-contained hydraulic system forces pistons containing the measurement transducers against the wall and clamps them in position until the sonic waveform information has been recorded. The pistons are then retracted and the probe is raised or lowered in the well as required. In the clamped position, the piezoceramic transmitter emits a sonic pulse which travels along the drill hole wall and is detected at the receivers in the form of compressional (P) and shear (S) wave motion. The receivers are designed to be sensitive to either the (P) wave or (S) wave motion as determined by the operator so that discrimination between the two wave types is improved by comparison of the respective output channels, and the travel time between transmitter and detectors can be accurately determined. Use of two receiver stations eliminates errors in timing of pulse travel because of electronic delays inherent in the probe.

Jan 1, 1981

By C. P. Mangelsdorf

This report deals with the efforts to develop a portable device suitable for underground use for the purpose of measuring the frequency of vibration of the horizontal chords of Birmingham roof trusses. Four devices are investigated and evaluated. An approximate emperical expression developed from a mathematical analysis provides a means of converting the frequency into tension. The method appears to be effective in mines with shale roof but requires some modification for other roofs.

Jan 1, 1983

By R. L. Anderson

Mechanical cleaning of bituminous coal in the United States was begun about 1875, with plants in western Pennsylvania and Illinois. The United States Geological Survey began to record the quantity of washed bituminous coal in 1906; and the series was carried forward to 1923, except that no data were collected, for 1922. This statistical work was transferred to the Bureau of Mines in 1925, and the collection of data on mechanical cleaning was resumed in 1927. Data collected before 1927 include only the coal that was washed at the mines and do not include that cleaned by pneumatic methods at the mines and that cleaned at central washeries operated by consumers.2/ The total bituminous coal washed in 1906 was less than 10 million net tons. In 1927, the first year for which complete figures are available for all types of mechanical cleaning, 28 million net tons of bituminous coal were cleaned in the United States.

Jan 1, 1951

By 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

By Michael D. Fenton

Social and political movements that had been gathering momentum over several years continued in 1993 to dramatically affect and inspire uncertainty on the global mineral industry. Privatization of government-controlled mineral industries continued throughout the world, especially in Africa, Asia, Central Eurasia, Eastern Europe, Latin America, and Western Europe. The reasons for privatization varied among regions and countries, but the trend was universal and was not expected to end soon. Regional trade blocks were being developed and expanded. The European Union (EU), the North American Free Trade Area (NAFTA), the Association of Southeast Asian Nations (ASEAN) , the Asia Pacific Economic Cooperation (APEC) , and the Latin American Southern Cone Common Market (MERCOSUR) were expected to contribute to reduced internal tariffs and increased minerals trade. Minerals consumption within the politically unstable former Soviet Union (FSU) decreased significantly without a simultaneous cutback in production, while its exports flooded the world's mineral markets. These exports into Western Europe and Japan, still in economic recession, depressed minerals and metals prices worldwide, especially for aluminum, magnesium, nickel, and potash. Increasingly restrictive environmental laws and land-access limitations in Australia, Canada, Western Europe, and the United States tended to discourage mineral resource development. However, the number of undeveloped countries in Latin America and Asia that encouraged exploration and development by revising mining and tax laws and regulations increased, thereby increasing investment opportunities for foreigners.

Jan 1, 1995

By D. E. Hirsch

A systematic procedure for separation, characterization, and semiquantitative analysis of high-boiling petroleum distillates was developed by the Bureau of Mines and applied to a 370° to 535° C distillate of Wilmington, Calif., crude oil. Separation procedures employed were isothermal and molecular distillation, chemical treatment, silica-alumina adsorption, and gel permeation chromatography. Characterization and analysis were accomplished by gel permeation chromatography correlations and mass and nuclear magnetic resonance spectrometry. These data should be useful in improving petroleum processing and utilization and in achieving the energy conservation inherent therein.

Jan 1, 1974

Provide coal mine shafts/slopes with an optimum coal mine shaft fire and smoke protection system composed of reasonably-priced, reliable hardware. Approach Accident and injury data indicate that a relatively low percentage (5%) of underground coal mine fires occur in shafts or slopes. Nevertheless, shaft or slope fires are extremely serious because they block critical escape routes for miners. That also can happen when combustion products resulting from fires in other mine areas contaminate shahs and slopes. Seeking the optimum configuration for a shaft/slope fire and smoke protection systems, the Bureau of Mines gathered data on the performance of existing fire detection devices and signal telemetry systems In several mines, and analyzed the generic protection needs of the U.S. underground coal mining industry. The optimum system developed by the Bureau provided an adequate number of detectors, a wide area of coverage, and an extensive data acquisition, analysis, display, and storage capability. This system. recommended for fabrication and in-mine testing, consisted of a microcomputer-controlled master panel located in the test mine's slope hoist room, and four remote units. Two of the remote units were placed on the surface atop upcast ventilation shafts, a third was situated underground near the slope bottom, and a fourth was installed at the slope top in intake air.

Jan 1, 1986

By D. E. Shanks

The Bureau of Mines investigated the effects of HCI concentration and solution temperature on the solubility and crystal form of the chlorides of Co, Mn, and Ni when sparged with HCI gas at temperatures of 20°, 40°, and 60° C. Increasing HCI concentration in solution caused the chlo-rides of Co, Mn, and Ni to crystallize (salt out) because of the common ion effect. The salting-out crystallization was most effective for NiCI2, which had a solubility of 0.7 pct at 20° C and maximum HCI concentration. COCl2 salted out to a minimum solubility of 9.4 pct at 20° C and 22 pct HCI concentration and increased in solubility at greater HCI concentrations because of the formation of chloride complexes. MnCl2 was intermediate in behavior. The effect of temperature on solubility was greatest for CoCl2 and least for NiCI2, 15 and 7 pct change, respectively, over the temperature range of 20° to 60° C. The salted-out chlorides of cobalt and nickel formed the hexahydrates and those of manganese formed the tetrahydrate in saturated metal chlo-ride solutions at 20° C and low concentrations of HCI. Increasing the temperature or the HCI concentration caused a 108s in waters of hydra-tion. At 60° C, the salted-out crystals of NiCl2 formed the tetrahydrate in HCI concentrations up to 18 pct and the dihydrate at higher concentrations, while cobalt and manganese chlorides formed the dihydrates, even in water.

Jan 1, 1985

By Ronald S. Conti

Fire is a major concern for those who work in underground mines. A mine fire can occur at anytime and often results in a partial or total evacuation of mine personnel and could result in the loss of lives. Therefore, having a workforce that is well trained to prevent, detect, and fight a fire is important. This paper focuses on responders’ preparedness for fire. Responders in this context are considered the entire workforce and are categorized as first, second, and sustained responders and evacuating miners. Quality training enhances ones awareness of mine fire hazards and promotes self-confidence in combating fires and responding to emergencies. Early warning systems and other escapeway aids such as a through-the-earth signaling and communication system, lasers and strobe lights are also addressed. The technological advancements that have been made can improve the state-of-preparedness for responders to underground emergencies and increase the chances of survival for escaping personnel.

By Edmund S. Leaver

This information circular is written is response to the marry requests for information on the recovery, or reason for poor recovery, of fine gold by the amalgamation process. Checking Gold Content Experience has shown that in many cases error has been made because the true told content of a particular sample or deposit was not known. Fire assays of representative samples give accurate results and should be considered final in determining the gold content.

Jan 1, 1928

By Gregory M. Molinda

The Bureau of Mines conducted an investigation into the occurrence of outbursts of salt known to be responsible for explosions, fatalities, and damage in domal salt mines. The purpose of the investigation was to develop a basis for predicting these outbursts based on geologic and associated physical properties of salt. The investigation was conducted at the Cote Blanche salt mine in southern Louisiana. Because outbursts are the primary mode of methane emission into the mine, more than 80 outbursts, ranging in size from 1 to 50 ft in diameter have been mapped. These outbursts generally are aligned and elongate parallel to the direction of salt layering. More than 200 salt samples, both random and selected, were tested for methane content. It was found that outburst zones are well correlated with high methane content. Detailed mapping also revealed that the zones are well defined, with salt crystal size abruptly increasing upon entry into the zone. The intensity of folding and kinking of the salt layering within the outburst zone also appears to increase. An interbedded sand layer occurring throughout the mine does not appear to be a significant source of methane. However, fine-grained salt may be related to outburst occurrence.

Jan 1, 1988

By D. Harrington

"A tabulation is printed below showing the accident record of the thirty-two mines of the Anaconda Copper Mining Co., in Montana, for the years 1915, 1916, 1917, 1918, 1919 and 1920, with summation for the six years. The table gives the number of shifts worked by each mine with the serious plus fatal accident rate for each 10,000 shifts worked.It is seen that in a total of 16,460,767.5 shifts worked by employees of the company's mines during this six-year period, there were only 2,005 serious and fatal accidents and of these, 200 were fatalities, leaving 1,805 serious accidents (a serious accident being one in which 14 or more days' time are lost). This is at a rate of 9,120 shifts per serious accident and at a rate of 82,304 shifts per fatality. Hence, if 300 days be adopted as a year's work, there would be one fatality per 274.3 years of work in these mines and one serious accident for every 30.4 years work.According to Bureau of Mines Technical Paper 286, (Metal-mine accidents in U. S. in 1919, by W. W4 Adams), during the years 1916, 1917, 1918, and 1919, the metal mines of the United States worked a total of 210,548,640 shifts and had 39,705 serious accidents. During the same years, according to the following tabulation, the mines of the above-mentioned company worked 11,958,978 shifts and had a serious accident rate of 0.995 accidents per 10,000 shifts worked. If the metal mines of the United States, working these 210,548,640 shifts, had this company's serious accident rate of 0.995 serious accidents per 10,000 shifts, the total number of serious accidents would have been only 21,000 or the country's metal-mine serious accidents would have been reduced nearly one-half, and there would be 18,705 fewer serious accidents than actually occurred."

Jun 10, 1921

By J. V. Scalera

Because of U.S. dependency on imported critical metals, the Bureau of Mines has conducted research to evaluate the possible substitution of nitrided low-alloy steels for higher chromium-containing alloys. The corrosion data for nitrided steels are limited primarily to the Soviet literature. The objective of this study was to determine the corrosion properties of six commercially nitrided low-alloy steels in a 5-wt % NaCl solution at pH 4. Weight-loss tests indicated that, in deaerated test solutions, most of the nitrided steels were less corrosion resist-ant than nontreated steels. However, electrochemical tests indicated that under more oxidizing conditions, nitrided materials are converted to a passive state with a significantly reduced corrosion rate. Elec-trochemical tests performed in an aerated environment confirmed the passivity of the samples in an oxidizing environment.

Jan 1, 1984

By Allen D. Look, Alan A. Sharp

"Churn drills for blast-hole drilling are important to the operation of most open-pit metal mines, but certain hazards are created through their use that cause fatal and nonfatal accidents.2/ The purpose of this circular is to present a code of safe practice prepared and followed at a large Arizona open-pit copper mine, where safety is recognized as a definite operating problem. Such a code, based upon a thorough study of available published information as well as practical experience gained from accidents and near accidents, is the result of considerable effort and monetary expenditure. It is hoped that other operations using churn drills may benefit by the code presented, either in comparison with existing rules or in the preparation of new operating instructions.The code presented is in use at the Morenci Branch of the Phelps Dodge Corn., Morenci, Ariz. Similar codes are used at the New Cornelia Branch, Ajo, Ariz., and in the waste-pit operation at the United Verde Branch, Jerome, Ariz.The authors gratefully acknowledge the cooperation of the Phelps Dodge Corp., whose personnel made: possible the collection of information included in this circular. Special acknowledgment is due Paul Simmons, safety engineer, and 3. U. Larsen, general drilling and blasting foreman, Morenci Branch, Morenci, Ariz.The importance of churn drills in Arizona mining is apparent when it is realized that at all the open-pit copper mines blast holes are drilled with this equipment. At Morenci, approximately 98 percent of the ground is broken by primary blasting of churn-drill holes.There has been a growing tendency in Arizona's copper-mining industry to change from underground to open-pit mining, with consequent increase in the use of churn-drill blast holes for primary blasting.3/Thirty-three churn drills are in use at Morenci for blast-hole drilling. The drills operate with 440-volt alternating current, and trailing drill cables, in 500-foot sections, connect with the portable drill transformer station.4/ Three Diesel-driven churn drills for drilling prospect holes also are in use. About 25 churn-drill shifts are operated currently on a three-shift basis. Ordinarily, a two-man crew is assigned to each drill; however, with prospect-drill crews a third man is added to handle the sampling.Benches are carried at a uniform height of 50 feet. Churn-drill holes are 9 or 12 inches in diameter and about 60 feet deep. The holes are 18 feet apart in hard waste and 21 feet in soft waste and ore, with toes from 11 to 13 yards at the shovel grade. Both the hole spacing and the toe have been increased gradually, until they are now 2 yards longer than in 1940. The average ground broken per hole is 3,500 tons, or 60 tons of ore per foot of hole drilled. The holes are drilled 10 feet below the bench to avoid leaving hard bottom, which requires secondary drilling and blasting.Starting with a 12-inch casing, the prospect holes average 1,200 to 1,500 feet in depth and terminate with 6-inch casing; the deepest hole drilled to date went to 1,735 feet.In addition, churn-drills are used at Morenci to drill blast holes in the silica pit, limestone quarry, and the tailings dam. Other irregular applications are the drilling of holes to set trolley roles and for concrete piling in building foundations."

Jan 1, 1950

By D. W. Frommer

Processing of nonmagnetic taconites by selective flocculation-des liming and anionic flotation of calcium-activated silica has been investigated using innovative procedures as a means of improving operating costs. Areas chosen for cost-cutting evaluation were grinding, fine screening, and water conservation and reclamation. The investigation was performed on Marquette range nonmagnetic taconites in the Bureau of Mines Twin Cities Metallurgy Research Center flotation pilot plant, at feed rates ranging between 900 and 1,100 lb/hr. With fully integrated water reclamation, flotation concentrates containing 65.8 percent Fe and 3.4 percent Si02 were made in the best operating period, with accompanying weight and iron recoveries of 40 and 74 percent, respectively. During this same period, the estimated cost of both flotation and water reclamation reagents was only $0.80 per ton of concentrate (1968 pricing basis). This cost is about 15 percent lower than obtained previously at this Center for flotation reagents only. The investigation demonstrated additional potential savings in operating costs of approximately $0.96 per ton of concentrate through autogenous grinding as a substitute for ballmilling. Fine screening of intermediate concentrates was employed advantageously, but the frequency of blinding may be a factor militating against use of the screen in this flotation system.

Jan 1, 1973

Provide roof to floor closure rate measurements during underground mining, especially retreat mining of coal pillars, thereby helping the miners predict an imminent roof fall. Approach An electronic device and rugged potentiometric extensometer were developed to provide a means fur measuring total closure and the rate of closure. How It Works An intrinsically safe, battery operated instrument is enclosed in a rugged, hand carried field case. The unit is constructed using low-power, integrated circuits to provide minimal battery drain. Two digital Light Emitting Diode (LED) readouts are used; one displays the rate, the other displays the total closure. The unit will measure one extensometer continuously or two extensometers alternately. Two potentiometric extensometers with a closure measurement range of 6 inches are attached to the readout unit. As the roof to floor closure changes, the potentiometric resistance

Jan 1, 1982

By N. E. Hanna

The effect of small percentages of sodium chloride on the incendivity of permissible explosives was studied by the Bruceton up-and-down technique in gallery tests. Both the reduction in incendivity achieved by addition of sodium chloride and application of the test method to explosives evaluation are discussed. It is demonstrated that the up-and-down technique in gallery testing is suitable for distinguishing differences in incendivity between different explosive compositions and between lots of the same composition. The study also shows that addition of relatively small quantities of sodium chloride tends to reduce the incendivity of explosives to firedamp, but addition of sodium chloride cannot insure reduced incendivity. Any improvement attributable to the salt can be counteracted by undefined variations in the explosive. The need for experimental investigations of a number of factors that may affect the safety of permissible explosives is emphasized. ACKNOWLEDGMENTS Grateful acknowledgment is made of the assistance of Roy L. Grant in analyzing for normality of distribution of the data obtained by the up-and-down methods and to Harold E. Tubbs for numerous calculations.

Jan 1, 1959

By David J. MacDonald

Stability constants, that is, equilibrium constants for complex-formation reactions, have been determined by a titrimetric method for complexes formed by the transition metal ions Ni2+, Cu2+, Zn2+, and Cd2+ with the structurally analogous bidentate ligands N-ethylethylenediamine and 2-(ethylthio)-ethylamine. The sulfur containing ligand was found to be the weaker of the two chelating agents for each of the four metals. Absorption spectra of the individual complexes have been determined in order to calculate their crystal field stabilization energies. The combined results suggest a linear relation between free energy of chelation and ionic radius of the metal ion.

Jan 1, 1972

By Kevin Connor

The Government's ban on all commercial mining operations, except for small-scale artisan exploitation of alluvial gold deposits, continued throughout 1985. Minerals produced were kaolin and lime for agricultural uses, and experimental peat harvesting for energy applications. The total value of the minerals produced during the year was estimated at $1.1 million .2 In early 1985, an agreement between the Government and Amoco International Oil Co. was ratified for a petroleum exploration concession covering 248,000 hectares of Lake Tanganyika. Onshore exploration in the Ruzizi Plain was already under way the last half of 1985. By yearend, enough seismic information was available that Amoco hoped to complete data analyses, determine onshore drilling sites, and begin drilling operations before the end of 1986. Also to begin in the latter part of 1986 were seismic studies of Lake Tanganyika. Throughout 1985, Amoco officials were negotiating with the Government of Zaire for expanding the exploration acreage into that country's portion of northern Lake Tanganyika and the Ruzizi Plain. An agreement between Amoco and Zaire could have important beneficial economic implications for both Zaire and Burundi, and onshore seismic work in Zaire logistically supported from Bujumburi could begin almost immediately.

Jan 1, 1987