Search Documents

By R. S. Dean

This report, the second of a series of annual reports of the Metallurgical Division to be released in this form covers the fiscal year July 1, 1935, to June 30, 1936. The technological work of the division is performed by sections. Thus, an efficient organization is provided to prosecute the various problems under investigation, and a logical system is set up for presenting the material contained in this report.

Jan 1, 1937

By H. A. Watson

Laboratory tests on three commercial methane detectors, two combustion- type detectors and one interferometer-type detector, were made by the Bureau of Mines to determine their response to certain single and multiple flammable gases mixed with normal and abnormal air atmospheres. Although both types of detectors responded accurately to methane-normal air mixtures, they did not show correct concentrations for other single flammable gases in air. Uniquely, the response of the interferometer-type detector to hydrogen was in a negative direction. The effects of individual gases in multiple flammable gas mixtures were approximately additive. In oxygen-deficient atmospheres the methane response of the interferometer-type detector erred on the high side, but only in very low oxygen concentrations were the combustion-type detectors affected-- showing low, erratic methane readings.

Jan 1, 1966

By Gregory M. Molinda

The Coal Mine Roof Rating (CMRR) was developed 10 years ago to fill the gap between geologic characterization and engineering design. It combines many years of geologic studies in underground coal mines with world-wide experience with rock mass classification systems. Like other classification systems, the CMRR begins with the premise that the structural competence of mine roof rock is determined mainly by the discontinuities that weaken the rock fabric. However, the CMRR is specifically designed for bedded coal measure rock. Since its introduction, the CMRR has been incorporated into many aspects of mine planning, including longwall pillar design, roof support selection, feasibility studies, extended-cut evaluation, and others. It has also become truly inter-national, with involvement in mine designs and funded research projects in South Africa, Canada, and Australia. This paper discusses the sources used in developing the CMRR, describes the CMRR data collection and calculation procedures, and briefly presents a number of practical mining applications in which the CMRR has played a prominent role.

Jan 5, 2007

By Gregory Molinda

Historically, coal miners have known that roof shales can deteriorate in contact with humid mine air, causing massive roof falls and injuries from falling rock. It is critical to recognize rocks prone to weathering and to adequately support these rocks in order to ensure the long-term stability of the openings. In a recent study, NIOSH has used a wet/dry cycling test to determine the moisture sensitivity of over 800 specimens of roof rock from 25 U.S. coal mines. Fireclays and some gray shales are the most moisture-sensitive. Rocks with disturbed bedding, in contrast to flat-bedded rocks, are also more sensitive to water. Black shales are relatively un-reactive to moisture and serve to protect more reactive gray shales above. Mines that have roof rocks with moisture-sensitivity indexes above 40% can experience slaking roof conditions, and many require high coverage surface controls. Three case studies are presented in which the moisture-sensitivity index is correlated to roof conditions underground, and can be used to indicate long term deterioration. Engineering measures are described to control moisture-sensitive roof. In one case, roof screen not only reduces injuries from rock fall but also is shown to reduce roof falls. Keywords: coal mining, roof control, slaking, roof support, rock falls

Jan 1, 2008

By Donelson A. Robertson

Includes a review of the state-of-the-art of explosives loading in the crushed stone and cement industries of South Florida and the development of a field test program for alternatives. Emphasis is on the loading of small diameter (2 1/4" or less) explosives. Test results ire evaluated for operational and economic feasibility. Details are described of an explosives loading method which involves placing cardboard tubes with external couplings through the hollow drill steel and then Loading explosives into the tube casings after the drill rig has moved off. This method eliminates the hazards peculiar to loading explosives Through the kelly bar. The alternative method can be performed by existing drill rigs with or without minor modification. With modification, improvement in yield per blasthole and/or primary crushing rate provides opportunity so offset some or all of the additional cost.

Jan 1, 1978

By G. R. Fitterer, M. B. Royer

The application of manganese in iron and steel metallurgy is very inter¬ esting historically. In general, ancient- irons and steels contained virtu¬ ally no manganese, probably because the available iron ores contained■only small amounts of the manganese oxides. Occasionally, samples of ancient irons were found to have appreciable amounts of manganese, but their presence is considered accidental and dependent upon the ore available to craftsmen of that time. Two specimens of iron (139;— made in 500 A.D. contained .negligible quantities of manganese. A sample of steel which constituted the base of .the Khan Baba pillar in India was probably processed in 12p B. C. by the1 cementa¬ tion of wrought iron. This material; contained 0.02 percent manganese and 0.70 percent carbon (20) . One Damascus-steel sword forged some time between 11'60 ' and l400 A. D. was found to contain 0.1^-i percent manganese and 0.j6l percent carbon. The manganese content of this bla.de was much higher than that of any other material of this type which has been analysed. In every other instance the manganese content was below 0.02 percent. A cast steel manufactured by the East India. Co. in India in the early nineteenth century, under the name of Wootz steel, contained rather appreciable amounts of manganese. This material was made by melting and refining fairly high-manganese pig iron prepared from high-manganese ore. Heath (106), who was working at the Co. plant between 1S20 and 1S40, was convinced that the manganese content of the steel was the determining fa,ctor in its high quality. He learned of certain difficulties English steel manufacturers were having in making even fair-grade steel, and analyses of the material indicated low manganese contents. This convinced him that.if the use of manganese could be introduced in England its steel would be greatly benefited. In consequence, he moved to England and soon was producing certain grades of ferromanganese for use with the crucible process. He recommended addition of this metallic material to the ingot mold just before pouring. It was soon found that inferior brands of steel containing only traces of manganese could be greatly improved by such additions. All metallurgists of that time became convinced

May 1, 1934

By M. A. Schellhardt, E. J. Dewees, R. Vincent Smith

"INTRODUCTION Abnormal material requirements of the nation at war impose an intensive demand upon many irreplaceable natural resources. Natural-3as reserves) for example, are being subjected at the present time to extensive depletion by large-scale withdrawals of gas to supply unprecedented demands for fuel and raw materials for the synthesis of strategic products. Fluids produced from many so-called gas-condensate type reservoirs have become an important source of hydrocarbons vital to the war effort.Development of gas-condensate type reservoirs in Arkansas, Louisiana, and Texas in recent years created many problems not common to ordinary gas-producing operations. Early in the development of condensate-type gas fields, general practices were evolved and applied to insure efficient re¬covery of the hydrocarbons existing in the gas phase under initial reservoir pressures and temperatures, put often the practices were predicted mainlyregardingupon generalized theory regarding the behavior of the fluids and were not always the most efficient, because field and laboratory procedure for testing these hydrocarbons had not progressed as rapidly or as far as field development. Specific information regarding the composition and properties of fluids ultimately recoverable from many gas-condensate reservoirs, especially, is lacking."

Oct 1, 1944

By Gregory M. Molinda

Extremely difficult ground conditions were encountered in the main belt entry in a room and pillar mine in West Virginia. Several generations of supplemental support, including cable bolts, cribbing, and Heintzmann jacks and beams failed to halt roof falls that threatened workers safety and the life of the mine. Polyurethane (PUR) was injected into 27 intersections in the roof and the results were monitored by borehole video camera. The mine had averaged 2-3 falls in the beltway per year and, since the roof injection, no roof falls have occurred. Pre- and post injection monitoring of test holes showed that stability can be achieved without filling all of the existing void spaces. Video logging showed that the project goal of building a beam from 2-6 ft into the roof was successful. Pre-injection monitoring of roof fractures uphole can delineate the zones to target for reinforcement, and avoid pumping PUR into large voids to little effect. Multiple-injection zones can be identified, and the entire intersection drill hole array can be optimized based on knowledge of the fractured zones. In addition, pre-monitoring can prevent excessive hydrofracturing in solid zones. Polyurethane injection is a proven method of rock stabilization in even the weakest, most broken ground. Optimization of the injection design by pre-injection video diagnostics can greatly contribute to the successful and efficient roof stabilization.

By Edward D. Thimons

This Bureau of Mines report presents expected levels of air pollutants in the face areas of oil shale mines, based upon data collected by the authors and previous investigators. Ventilation requirements to maintain these pollutant levels below their threshold limit values and Federal and local mine air quality standards are discussed. Two practical face ventilation systems are discussed in terms of actual in-mine test experience.

Jan 1, 1986

By G. M. Kintz

"Methods and costs of rock-dusting bituminous coal mines have been discussed in various publications by the United States Bureau of Mines and others.3 This paper discusses the present methods and cost of dusting at the Swastika mine of the St. Louis, Rocky Mountain and Pacific Co., Raton, N. M.In the Swastika mine the recommendations of the United States Bureau of Mines with regard to rock-dusting are followed at least as well as in any mine in the States of Wyoming, Colorado, and New Mexico. This mine is located at Swastika, N. M., approximately 4 miles west of the town of Raton and is in the Raton coal seam. The mine is rated as gassy and produces approximately 1,000 tons of coal per day.A mining system known as the ""room-and-pillar with cut-offs"" is used which results in recovery of nearly 100 per cent of the coal. The mine employs approximately 250 men.Ventilation is maintained by a Sirocco fan so arranged that the air current may be reversed and exhausting approximately 130,000 cubic feet of air per minute at 3 inches water gauge. This fan is supplemented by two auxiliary fans for emergency use. Three main entries penetrate the hill in a straight line for approximately 8,000 feet. The haulage is through the center entry, which is also used as the intake in conjunction with a two-compartment concrete-lined shaft located at the end of the entries. The main return for 3,000 feet inby the fan is 12 feet wide and 7 feet high. For this distance the ribs have been reinforced by a wall made of coke-breeze blocks plastered over with cement. Solid concrete blocks are used for the top row of blocks of the wall. Steel 10-inch I-beams spaced 40 inches apart center to center are supported on these solid blocks and thus support the roof. The next 1,000 feet inby has the same area, but the cement blocks extend to the roof, as no crosspieces are needed. The airways are kept clean and well rock-dusted.A rather unique system is used to handle gas feeders along the intake and haulage entries. There these feeders occur in the roof or where gas is apt to collect in high points along the haulage, tin funnels as large as 3 feet in diameter are placed near the roof. From these a 2-inch or other suitable-sized pipe is run into the return through the wall of the nearest break-through. A valve on this pipe line controls the amount of air pulled. These devices keep the high places clear of any gas, even when strong feeders are encountered.Fifteen-ton electric trolley locomotives are used on the main haulage and approximately 30 roller-bearing oars, each having a capacity of approximately 3,000 pounds of coal, compose a trip. All loaded tripe carry steel drags on the last car, and automatic derails are located at advantageous points throughout the mine.All loaded trips are thoroughly sprinkled on the sectional partings and at the main parting. The track is sprinkled every idle day, or if needed, every day; from a large tank mounted on a truck hauled by a motor. Neither nozzle nor spray is used, as these were unsatisfactory. The water leaves the tank. through a 11/2-inch valve and is permitted to flow on the road through a horizontal 11/2-inch T. Water is obtained from filling stations located throughout the mine. It is stated by the officials that the use of this method of sprinkling permits the entire haulage roadbed to be wetted down in two hours."

Mar 1, 1930

By Paul M. Tyler

The outstanding trend in the graphite market is the fast-growing demand for cheaper qualities of graphite and the declining consumption of the more expensive varieties. The manufacture of graphite, crucibles for melting metals was one of the earliest applications of the-mineral and for many years constituted by far the leading source of demand. In later, years, however; and more especially since the Great War, the increasing demand for high-grade steel ingots and castings instead of enlarging crucible sales has permanently curtailed the domestic demand for crucibles because it has hastened the introduction of electric, oil or gas fired furnaces to replace the older types requiring pots to hold the metal during melting. While there has been a substantial increase in the use of graphite for miscellaneous refractories the total consumption for such purposes is too small to offset the shrinkage in demand for crucible making, and though it consumes the better and hence more expensive grades of crystalline flake graphite, it does not call so insistently for the still costlier Ceylon grades.

Jan 1, 1929

By Gerrit V. R. Goodman

A laboratory study assessed the impacts of water spray pressure, face ventilation quantity, and line brattice setback distance on respirable dust and SF6 tracer gas concentrations around a continuous mining machine using a sprayfan or directional spray system. Dust levels were measured at locations representing the mining machine operator and the standard and off-standard shuttle car operators, and in the return airway. The results showed that changes in all three independent variables significantly affected log-transformed dust levels at the three operator sampling locations. Changes in setback distance impacted return airway dust levels. Laboratory testing also identified numerous variable interactions affecting dust levels. Tracer gas levels were measured on the left and right sides of the cutting drum and in the return. Untransformed gas levels around the cutting drum were significantly affected by changes in water pressure, face ventilation quantity, and setback distance. Only a few interactions were identified that significantly affected these concentrations. Gas levels in the return airway were grouped by face ventilation quantity. Return gas levels measured at the low curtain quantity were generally unaffected by changes in water pressure or curtain setback distance. At the high curtain quantity, return airway gas levels were affected by curtain setback distance. A field study was conducted to assess the impact of these parameters in an actual mining operation. These data showed that respirable dust levels may have been impacted by a change in water pressure and, to a lesser extent, by an increase in curtain setback distance. A series of tracer gas pulse tests were also conducted during this study. The results showed that effectiveness of the face ventilation was impacted by changes in curtain flow quantity and setback distance. Laboratory testing supported similar conclusions.

Jan 1, 2004

The Bureau of Mines is responsible for a broad spectrum of programs for meeting the diverse and changing mineral resource needs of the Nation. These programs are managed by the Director and two Deputy Directors, who formulate general policy and program direction from the Washington, D.C., headquarters. A senior advisory staff, consisting of the Chief Staff Officer, Chief Scientist, and Chief Mining Engineer, provides advice and consultation to the Director on a wide range of scientific and technical matters and acts on behalf of the Director to maintain liaisons with other government agencies, mineral industries, and professional societies. Bureau program activities are classified into two major functions: (1) Developing new and improved technology that will make the production and processing of minerals more efficient, safer and more healthful for mineral workers and the public, and more compatible with a quality environment.

Jan 1, 1979

This is the second of a series of reports on properties of commercial motor fuels made pursuant to a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the Department of the Interior. The first report gave data oil motor gasolines sold during the minter of 1935-36.3/ These gasoline surveys report results of inspections, in oil-company laboratories, of samples of gasoline obtained by representatives of oil companies from service-station pumps in marketing areas throughout the country. In the present survey are presented inspection data on 239 samples of regular- price gasoline, 166 samples of premium-price gasoline, and 157 samples of third-grade gasoline, a total of 562 samples collected during the summer of 1936.

Jan 1, 1937

By G. B. Shea

"In 1928, there were 47 fatal accidents in the California petroleum industry, 14.6 per cent more than occurred in 1927 when 41 men lost their lives in the drilling, producing, manufacturing, and marketing divisions of the industry. This increase in the number of fatal accidents for 1928 has caused the first upward trend in the fatality curve of the California petroleum industry since 1923. In no other year during the 6-year period have the fatalities in any one year been greater than those for the preceding year. This fact should be given serious consideration and study by the petroleum industry, and an endeavor should be made to cause the number of fatalities again to decrease and conform to the previous gradual declining trend of the fatality curve.The following chart shows the trend of fatal accidents during the past six years:Of the 47 fatalities in 1928, 30 occurred in the drilling and producing division, 1 in the pipe line and transportation division, 14 in the refining division, and 2 in the sales and marketing division. A comparison of the number of fatalities in each division for 1927, and 1928, is given in the following table:3"

Sep 1, 1929

By Ch. D. Taylor

Past studies with blowing face ventilation systems have shown that using a machine-mounted scrubber and water sprays can reduced methane levels at the face. The current research was conducted to determine how the sprays and scrubber interact to reduce methane levels, and what spray configurations provide the best face ventilation when used with a scrubber. Testing was conducted in a ventilation test gallery designed to simulate a full-scale mine entry. In the entry, a model mining machine, equipped with a simulated dust scrubber and water spray systems, was located at the face of a 6.1 m (20 ft) box cut. Face ventilation was provided by a blowing curtain located 12.2 m (40 ft) from the face. Methane released from a manifold at the face was measured at six locations near the face to compare the ventilation effectiveness of the spray systems while operating with and without the scrubber. Airflow movement across the face was affected by the spray configuration and scrubber operation. Average face concentrations were lowest when directed sprays were used with the scrubber. Varying the direction of the scrubber exhaust affected face methane levels.

The Technology Transfer Seminar on Mine Communications held on March 21-77, 1973, at the Pittsburgh Mining and Safety Research Center, Bruceton, Pa., presented information about recently developed equipment, instruments, and techniques for use in mine communications systems. All of the basic ideas presented in the fine seminar are operational in the Bureau of Mines Safety Research Mine in Bruceton.

Jan 1, 1974

By Alvin Schallis

The. problem of supplying enough magnesia for the American war effort has become highly important. Before hostilities began, only about two-thirds of our, require vents came from domestic sources; now they must supply almost all the magnesia we need. A further burden is placed upon our own supply by the fact that more and more magnesia is being required, not alone to pace the war tempo of general industrial activity, but also to replace chrome ore in refractories and to make magnesium metal. The domestic magnesite and brucite industry is equipping itself to satisfy much of this greater demand for magnesia, but the remainder must be obtained elsewhere. The principal sources of magnesia are magnesite, brucite, dolomite or high-magnesium limestone, natural brines, sea water, salt-works bitterns, magnesium silicates, and magnesium salts. Although dolomite is tae subject of this paper, it should be considered in perspective with all these highly competitive sources of magnesia.

Jan 1, 1943

By Steven J. Schatzel, Robert B. Krog

Frictional ignitions are defined as the ignition of a flammable mixture of methane and air that is initiated by frictional heating. Ignitions created through the addition of energy from open flames and exposed electrical circuits are not included in this analysis. Energy released in a roof fall that creates a spark and ignites a methane mixture would be considered a frictional ignition. Frictional ignitions represent the majority of all ignitions in underground coal mines. Over the study period of 1983 to 2005, a total of 1993 ignitions were reported in underground bituminous coal mines in the United States, of which 1589 were frictional ignitions. Reportable ignitions to the Mine Safety and Health Administration (MSHA) are any unintentional occurrences of flame underground regardless of duration. Frictional ignitions were reported in 155 mines and 13 states. Continuous miners represented the largest source for frictional ignitions with 1090 (68.6% of all frictional ignitions). Longwall mining operations represented the highest concentration of frictional ignitions during this study period with 1365 frictional ignitions (85.9% of all frictional ignitions). The 17 mines with the most frictional ignitions were all longwall mining operations and had 1130 frictional ignitions (307 from the shearer) that represented 71.1% of the total. In 1983, mines with frictional ignitions represented 6.9% of operating underground mines and 36.6% of total underground coal production. The percentage of operating underground mines with frictional ignitions and their total production has increased steadily and in 2005 represented 9.8% of active mines and 46.2% of underground coal production. The three coalbeds with the highest number of frictional ignitions (Blue Creek, Pittsburgh No 8, and Pocahontas No 3) had 1049 ignitions that represented 66.0% of all frictional ignitions. The three states with the highest number of frictional ignitions were Alabama (710), Virginia (247), and Pennsylvania (242) that represented 75.5% of the total. Frictional ignitions peaked in 1991 with a high of 114. In 2005, only 34 frictional ignitions were reported. If only frictional ignitions that occur at the face are considered, there have been no fatalities since 1983. Since this time, there were 33 ignitions that caused 53 workers to lose a total of 2912 working days. When including ground falls, then there have been four frictional ignitions with one incident causing two fatalities and injuring eight workers. From 1983-1991, underground productivity and the number of frictional ignitions increased. However, productivity continued to increase from 1991-2000 while total frictional ignitions fell, thereby disproving this connection between productivity and frequency of frictional ignitions. Ninety percent of all frictional ignitions occurred in underground coal mines that liberated more than 393 L/s (1.2 MMcfd million cubic feet per day) of methane through the main ventilation system. Although methane production is not the determining factor for the occurrence of frictional ignitions, it is a good indicator of the anticipated frequency.

By E. J. Murphy, A. P. Rowles, John C. Holtz

"INTRODUCTION The use of sheaths or hollow cylinders of flame-extinctive materials surrounding cartridges of permissible explosives has been developed during the last few years; the history of sheathed explosives in their salient development in Belgium was treated recently in a publication of the Bureau of Mines. 6/ This development is of great interest in explosives technology, for it holds possibilities of reducing further the ignition hazards that may cause many coal-mine disasters. The township interest in sheathed explosives in this country is attested by the passage of some State laws permitting the use of such explosives on shift 7/; inquiries are received in increasing numbers concerning the effects of sheaths on practical hazards as well as the general technology underlying their use."

May 1, 1943