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Eliminate accidental tramming of a cleanup tractor. Approach A switch was installed in the operator's seat cushion to pre-vent the cleanup tractor from tramming without an operator in the driver's seat. How It Works The operator must be seated, and the Forward/Reverse Switch (that controls tramming direction) must pass through the NEUTRAL position before the vehicle will tram. See Figure 1. A pressure-sensitive seat cushion switch, a solid-state relay, and a double-contact relay were added to the control circuitry of an S & S BMUAT -88 cleanup tractor to create this tramming interlock. The weight of the operator on the cushion closes the seat cushion switch (Figure 2, A). This activates the solid-state relay (B), which completes the initial circuitry. Moving the For- ward/Reverse Switch (C) to NEUTRAL energizes the coil in the double-contact relay (D) and closes both contacts. One contact completes a sustaining circuit which keeps the double-contact relay energized. The second contact transfers power to the remaining contacts within the Forward/ Reverse Switch. These circuits are shown in greater de- tail in Figure 2.

Jan 1, 1978

By Stephen W. Lambert, Michael A. Trevits

The Bureau of Mines examined the wellbore of a vertical gas drainage well in the Mary Lee coalbed to determine the results of specific completion procedures in coal. A jet-slotting tool was used to cut four vertical slots through the casing about 1 ft below the coalbed. Even though stimulation treatment pressure was excessive, hydraulically induced channels were contained entirely within the target coal zone. Sand-filled, induced channels were horizontal, inclined, and vertical, and were propagated in directions similar to bedding planes, rock joint, and coal cleat directions measured in the mine. Variable gas flow rates, recorded during the productive life of the well, were attributed to chronic downhole pump malfunction and the slotted casing below the production zone.

Jan 1, 1978

By N. Kumar Kittusamy

By J. H. Heginbotham

As part of the total metallurgical system to recover metals from secondary resources, the Bureau of Mines conducted froth flotation research, using cationic reagents to recover glass from urban refuse. Batch flotation tests showed that high-quality cullet can be obtained from glass-rich aggregates derived from municipal incinerator residues and unburned refuse. This was confirmed by pilot plant operations treating 350 pounds of flotation feed per hour. Aggregates containing 85 to 90 percent glass were wet-ground to minus 20 mesh, deslimed in two stages, and fed to flotation cells. The glass was selectively floated using an amine collector, usually in an amount under 0.2 pound per ton of solids in the feed. The glass concentrates from the rougher cells were cleaned by refloating two or three times. Over 90 percent of the glass in the deslimed feed was recovered in the cleaned concentrates.

Jan 1, 1978

This chapter presents MSHA data on mine employment and active mining operations during 1986-1995. Figures 3-1 through 3-10 show, for each commodity, the location of mine operations in 1995, and employee hours and active mining operations by year during 1986-1995 for mine operators. For coal and nonmetal operators, the number of active mining operations and the number of employee hours decreased over the 10-year period. For metal operators, the number of active operations decreased, while the number of employee hours increased. For stone and sand and gravel operators, the number of active operations and the number of employee hours remained about the same. Figures 3-11 and 3-12 show that over the 10-year period, there was an increase in the proportion of hours worked by contractors in coal mining, while the overall employment decreased. For metal, nonmetal, stone, and sand and gravel combined, the proportion of contractor hours increased, with overall employment also increasing. Table 3-1 shows the distribution of hours worked during 1986-1995 by commodity and type of operation. For coal, the majority of hours worked were in underground mines. For metal, nonmetal, and stone, the largest number of hours worked were in mills and preparation plants. For sand and gravel, all work hours other than office were in surface mines. [ ]

Jan 5, 2000

By James Rowland, Isaac Zlochower, Richard Mainiero, Michael Sapko

The National Institute for Occupational Safety and Health (NIOSH) carried out exploratory laboratoryscale studies to identify factors that may contribute to nitrogen oxides (NOx) production associated with non-ideal detonation of blasting agents. Explosive admixture with drill cuttings, loss of fuel oil in ammonium nitrate and fuel oil (ANFO) from wicking, ammonium nitrate dissolution with water, degree of explosive confinement, ANFO density, and critical diameter were identified as contributing factors to increased NOx production under the laboratory test conditions. Experiments were also conducted to examine the effectiveness of various additives in reducing the NOx production from ANFO, emulsion, and ANFO/emulsion blends. Aluminum powder, coal dust, urea, and excess fuel oil in ANFO formulations were tested and were found to reduce both the nitric oxide (NO) and nitrogen dioxide (NO2) production. Fumes measurements were obtained in the NIOSH underground closed chamber from the detonation of 4.5-kg (10 lbs) charges in schedule 80 seamless steel pipe and from detonations in light weight galvanized steel stove pipe. Some exploratory tests were also conducted with 0.8-kg (1.8 lbs) charges of pulverized ANFO initiated with 0.08-kg (0.18 lbs), 50/50 (Pentolite) boosters (in the NIOSH 12-ft (3.7-m) diameter steel sphere) to measure the degree of fumes production associated with post-detonation oxidation. Ammonium nitrate, emulsion and Pentolite boosters were also detonated in an oxygen-poor environment.

By M. M. Fine

A satisfactory mean: of beneficiating a Brazilian phosphate rock was developed in a mineral-dressing-research study by the Bureau of Mines. High-grade concentrates well ever the specified minimum grade of 70 percent tricalcium phosphate, were produced, with goad recoveries by agglomerate tabling and flotation. A lower gads but usable secondary product was recovered by sedimentation of the minus-200-mesh fraction of the ore. The ore wan representative of an extensive deposit recently discovered near Recife in the State of Pernambuco, Brazil, which will be exploited in a plant planned to eventually produce at the rate of 500,000 tons of concentrate annually. Although Brazil has been reported to Lave a substantial reserve of phosphate rock,3/ the country has never been more than a small producer of this commodity. From 1945 to 1950 the highest production of phosphate rock attained in Brazil amounted to 10,421 tons. Production in 1949, the most recent year for which figures are available, was 4,553 tons.4/

Jan 1, 1954

By Ivette E. Torres

The series summarizing the prices of the major nonferrous metals on the stock exchanges of the United States and the United Kingdom (London Metal Exchange) has been continued this year in tables 22 and 23. Time constraints have prohibited preparation of other price information that has appeared in this study in previous years. Users are urged to consult the 1993 U. S. Bureau of Mines publication Metal Prices in the United States through 1992, which gives an analysis of historical price series and trends, or the 1993 edition of Mineral Commodity Summaries for current U.S. prices on non fuel commodities, and to utilize U.S. Department of Energy sources for information on fuel material costs.

Jan 1, 1994

By W. H. Young

THE DOMEST[C bituminous coal and lignite industry remained fairly steady in 1959 compared with 1958. Although mechanization continued to expand and production increased slightly, consumption, average value, exports, and employment decreased. The percentage of underground production mechanically loaded, the percentage of total production mined by stripping, and tonnage per man per day were at their highest levels. Production.-The output of bituminous coal and lignite in 1959-412 million tons-was 0.4 percent greater than the 410.4 million tons produced in 1958. Production was retarded in 1959, largely owing to the steel strike and reduced exports.

Jan 1, 1960

By C. H. Elder

An experimental degasification program using a vertical borehole and vacuum pump to drain gas from the gob area of a longwall panel was successful at Bethlehem Mines Corporation, Cambria Division, No. 33 coal mine. Sixty-one million cubic feet of methane has been exhausted during a 9-month period. Daily production time in the panel increased as a result of lower methane levels in the returns. Removal of large quantities of methane in this way and the exclusion of it from the ventilating system will provide reduced cost in mine ventilation and provide a safer environment for the mine.

May 1, 1969

By L. C. IlsLey, M. W. Means

The United States Bureau of Mines under provisions of Schedule 20 issues approvals covering complete operating units such as loading machines, room hoists, and storage-battery locomotives. Certain manufacturers design and build entire machines. Other manufacturers purchase a part or all of the electrical accessories from manufacturers of electrical equip- ment and assemble them, thereby making up a permissible unit. Before the assembler purchases electrical accessories for use in such contempla.ed units he may require certain information from the accessory manufacturer as to whether these par- ticular accessories are suitable for assembly in his proposed permissible outfit. In order to aid accessory manufacturers in marketing their product, a provision was incorporated in Schedule 20 whereby tests might be made on individual accessories and reports rendered as to the suitability of a given accessory for use in permissible assemblies. The section of Schedule 20 which permits this special work reads as follows:

Jan 1, 1932

By Kenneth M. Earl

The purpose of this investigation was to obtain subsurface information on the John Burdette barite-fluorite deposit, Garrard County, Ky. The deposit was intersected in each of five inclined diamond-drill hales aggregating 1,163 feet. All holes were drilled from the hanging wall of the deposit; the inclinations varied from minus 41° to minus 75°. Disseminated metallic sulfides were noted in the drill cores from holes 1, 2, 4, and 5. The deepest drilling was hole 5, which intersected the deposit at approximately 490 feet down dip. Visual inspection of the cores did not indicate mineralization of economic importance; therefore, no chemical analyses were conducted. Condensed logs of diamond-drill cores are included in this report. All drill cores were shipped to the Bureau of Mines core library in Minneapolis, Minn., for future reference,

Jan 1, 1959

By Maria I. De Rosa

Table 55 and figure 19 show the number of fires and fire injuries for stone mills by state during 1990-2001. Table 55 also shows the injury risk rates, employees' working hours, and lost workdays. In all, 118 fires occurred in 33 states. Seventy-six of the fires caused 82 injuries (including 8 fires and 6 injuries involving contractors). The yearly average was 9.8 fires and 6.8 injuries. The Ewhr value was 873 x 106 hr (In = 0.019), and the LWD value was 1,911. Missouri had the most fires (16 fires and 9 injuries), followed by Pennsylvania (15 fires and 14 injuries), Michigan (9 fires and 5 injuries), and Virginia (7 fires and 5 injuries). Of these states, Virginia had the highest injury risk rate value (In = 0.09 1). Table 56, partly illustrated in figure 20, shows the number of fires, fire injuries, risk rates, employees' working hours, and lost workdays by time period. The number of fires and fire injuries decreased during most of the periods, with a sharp increase during the last period. The number of employees' working hours increased throughout the periods. The In values follow patterns similar to those shown by the injury values. Tables 57-63 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 21 shows the major variables related to fires for 1990-2001. Table 63 shows the fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

In the past, mine management has been concerned with removing water from active mining sections primarily because it hampered the movement of mining equipment and aggravated the working condition of the miners. Pumping water to sumps and gravity drainage by ditching have proven successful in mines for minimizing section down time due to water influx. However, with the advent of more strict pollution laws the mining engineer must now be concerned with keeping water out of the section and also with preventing it from causing pollution. A review of the handbooks and textbooks used in the mining engineering curricula reveals that little has been written concerning acid mine water prevention or control in underground coal mines. Additionally, the review of the curricula of mining schools indicates they are not teaching the engineering students the necessary techniques of mine water management as they relate to the abatement of mine water pollution.

Jan 1, 1970

By Steven J. Page

The increasing concern for dust control in metal and nonmetal mining prompted the Bureau of Mines to investigate the comparative effectiveness of three wet dust control techniques for face drilling. Previous attempts to achieve effective dust control on face drills with dry collectors have not met with success, the largest problem being sustained effective dust capture at the face. Results show that (1) foam-through-the-drill can provide 95-pct average total dust reduction in gypsum; (2) water mist-through-the-drill can provide approximately 91-pct average total dust reduction and 93-pet average respirable dust reduction in salt; (3) external boom-mounted water sprays can provide approximately 50-pet average dust reduction for both total and respirable dust in salt. The investigation showed that (1) foam and water in small quantities are very effective dust control techniques for face drills when applied through the drill steel at the point of dust generation, and (2) boom-mounted water sprays are only minimally effective for dust control on face drills.

Jan 1, 1981

By Dhaval Patel, Kim Witte, Charles Vaught, Michael T. Stephenson, Steve Booth-Butterfield, Cynthia Zuckerman, Brian L. Quick

This longitudinal field study was designed to encourage Appalachian coal miners in West Virginia and Pennsylvania to engage in hearing-protection behaviors. Method: Participants were mailed postcards that featured either a positive, negative, or neutral message on the outside of the postcard and a message encouraging hearing protection behaviors on the inside. The first posttest measurement of the effectiveness of the persuasive messages was conducted about a week after the postcards were mailed. The delayed posttest measurement was conducted six weeks later. Results: Responses from 307 coal miners revealed that the positive or neutral messages generated significantly more self-reported hearing protection behaviors than the negative message. Identical results were obtained in a delayed posttest assessment of miners' self-reported hearing protection behaviors. The positive message was also more effective than either the neutral or negative message in preventing defensive mechanisms from emerging over time. Impact on Industry: Positive and neutral messages were convincingly more than negative messages in facilitating self-reported hearing protection behaviors among coal miners. Similarly, the positive messages kept defensive processes at bay. Keywords: Hearing protection; Hearing loss; Coal miners; Campaign; Messages

By J. K. Whyatt, B. G. White

Various methods of monitoring slip movements on bedding planes, as well as examination of rock burst damage in stopes, suggests that rock bursts in the Lucky Friday Mine are closely associated with these movements. Slip displacements along bedding simultaneously reduce the physical dimensions of stopes and increase compressive stress along stope margins. Such changes, in turn, contribute directly to rock bursts and the sudden failure of volumes of rock and cemented sandfill surrounding stopes. The distribution of seismicity and several mining-induced and premining structures resemble those described in South African gold mines. These suggest fundamental similarities in seismic sources and mechanisms of rock burst damage.

By H. R. Shell

The systems MgO-MgFa-SiO2, at 2 and 4 weight-percent Li2O and at 3.8 and 7.7 weight-percent Na2O were investigated by solid state reaction at 1,200° C. The results are summarized in four ternary diagrams. Besides the expected humites and simpler silicates or fluorides, proto-amphibole and water-swelling fluormicas or fluormontmorillonoids were found in the systems containing lithium and monoclinic fluoramphiboles, water-swelling fluormicas or fluormont-morillonoids, and nonwater-swelling fluormicas were found in the systems containing sodium. These latter compounds were not in the base system MgO-MgF2-SiO2.

Jan 1, 1962

Louisiana's coal reserves, located in the north-western part of the state, consist entirely of lignite, with estimated recoverable reserves of about a billion tons. Although lignite deposits were discovered in the early 1800s, the first documented use of lignite occurred at the federal arsenal near Shreveport during the Civil War. By the late 1800s, lignite use was common by blacksmiths, railroads, and steamboats. Lignite production ceased, however, from the early 1900s until 1985. A new lignite mine permitted September 1, 1985, produced 0.2 million tons in its first year. The operation uses a seven-mile-long conveyor to transport lignite to the associated mine-mouth power plant. The surface coal mining reclamation and enforcement program in Louisiana was approved October 10,1980. Louisiana's Abandoned Mine Reclamation Plan was approved December 10, 1986

Jan 1, 1992

Eliminate the occurrence of false fire detection alarms caused by the operation of diesel-powered vehicles in underground coal mines. Approach Fire detection systems used in underground mines are based on measurements of airborne combustion products such as carbon monoxide or smoke particles. The effectiveness and credibility of these systems can be reduced by the occurrence of false alarms that result from the operation of diesel-powered equipment, which produces the same combustion products. False alarms end up being very costly to the mine operation in terms of downtime and labor needed for verification. To improve upon current fire detection systems used in the presence of internal combustion engine products, the U.S. Bureau of Mines developed a fire detector that can discriminate between the occurrence of real mine fires and the presence of engine smoke.

Jan 1, 1989