Search Documents

By T. J. Ballard

The Conrad Hill mine vas first opened as a gold mine about 182 and has been operated at various times since then. The Bureau of Mines, as part of the strategic minerals program, mapped and sampled the accessible mine workings. The work failed to reveal appreciable copper values or evidence of additional ore deposits.

Jan 1, 1948

By Thomas M. Barczak

The safety of mine workers depends on the proper installation of roof supports to prevent the ground from collapsing into the working areas of an underground mine. As new support systems are developed, they need to be properly evaluated to make sure that they are capable of providing adequate roof support before they are first used in a mine. In addition to making certain that the supports meet basic safety criteria, the limitations of the support need to be fully defined in order to avoid improper application of a particular support design. The National Institute for Occupational Safety and Health (NIOSH) operates a world-class facility called the Safety Structures Testing Laboratory. This laboratory contains a unique load frame, the Mine Roof Simulator, which is capable of simulating the ground behavior in underground mines for conducting full-scale evaluations of roof support systems. Safety performance testing protocols using the unique Mine Roof Simulator have been developed for both standing roof support systems and longwall shield supports. The purpose of this paper is to describe these test procedures. The protocol for standing roof supports incorporates seven test series:( 1) uniform loading baseline tests, (2) height evaluations, (3) asymmetric loading, (4) biaxial loading, (5) load rate studies, (6) active loading determination, and (7) static loading evaluations. For longwall shields, a four-series test program that accurately simulates in-service conditions on a longwall face is proposed. This test program consists of (1) transfer of horizontal load to the caving shield-lemniscate assembly (zero-friction test),(2) point loading of shield joints due to lateral movement or rotation of the canopy, (3) evaluation of leg socketand leg cylinder integrity, and (4) face-to-waste racking of the shield. In addition, an evaluation of the shield’s hydraulic components will be conducted prior to the performance testing. These protocols will provide state-of-the-art safety performance evaluations of emerging support technologies, as well as a means to assess the safety of both new and aging longwall shields. Hence, this effort will enhance the safety of mine workers by ensuring that critical support elements are properly designed and that aging supports are retired before their support capability is jeopardized.

Jan 10, 2000

By Frederick L. Hoffman

Miners' nystagmus is the result of a peculiar form of eyestrain, which often results in impairment of vision and a consequent diminu- tion of the wage-earning capacity of the workman. Historically it has been pointed out by Shufflebotham that "This disease was first recognized by Gillett, of Sheffield, about 1854, although no case was mentioned in medical literature until 1861, when the symptoms were described by De Conde, a Belgian physician. Cases were reported by Pepp Müller as early as 1860, by Von Graefe in 1873, and by Bell Taylor, of Nottingham, and by Nieden in 1874. In this country (England) we are indebted to a very large extent to the observations and writings of the late Simeon Snell and for his pioneer work on this many-sided disease; in France Dransart occupies a similar position." In the treatise on "The Effects of Arts, Trades, and Professions," by C. Turner Thackrah, published in London in 1832, it is stated that- The complexion of the colliers, even after the removal of the dirt, is generally sallow and unhealthy. Their eyes, from the swelling of the lids, appear small, are affected with chronic inflammation and intolerant of full light. * Sickness and vomiting sometimes affect persons at their commencing the employ; and many, after a few years' trial, are obliged, by the injury which their health has sustained, and especially by the weakness of their eyes, to leave the mine. According to Greer, an authority on industrial diseases and acci- dents, miners' nystagmus occurs in 5 per cent of all miners, but it is quite probable that the reference is to European coal miners rather than to men employed in all branches of the mineral industry. According to the same authority, miners' nystagmus "is associated with a twitching of the eyelids and with considerable diminution of the range of movement of the eyes, and is particularly liable to occur in patients whose vision is subnormal owing to errors of refraction, especially astigmatism. It causes much inconvenience to those suf- fering from it and prevents them from following their usual occupa- tion as, owing to the movements of the eyes, everything at which they look appears to be in a state of perpetual motion, and in conse-

Jan 1, 1916

By Jeanne A. Zimmer, Charles D. Taylor, Edward D. Thimons

On a continuous miner coal face methane concentrations are affected by the quantity of fresh intake air reaching the face. When mining the box cut on a 12.2-m (40-ft) two-pass extended cut face, the continuous miner is always at the point of deepest penetration, and operation of the machine-mounted dust scrubber and water spray system improve the flow of fresh air to the end of the box cut. However, when the continuous miner leaves the box cut to begin cutting the 40-ft slab, little is known about how much ventilation air reaches the end of the box cut. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health conducted a full-scale study to answer this question. Tests were run to determine how much ventilation air reaches the end of the box cut with the continuous miner at three locations in the 40-fttwo-pass extended cut mining sequence; at the end of the 40-ft box cut, at the start of the 40-ft slab cut, and 6.1 m (20 ft) into the slab cut. During these tests, methane gas was uniformly released at the end of the 40-ft box cut. Methane concentrations measured0.3 m (1 ft) from the roof and face of the box cut were used to estimate face airflow quantities. Fresh air flow rates of 1.89and 4.72 m/sec (4,000 and 10.000 cfm), scrubber flow rates of 0, 4,000 and 10,000 cfm, water spray pressures of 0 and3827 kPa (0 and 120 psi), and a blowing curtain setback position of 15.2m (50 ft) were used during these tests. To improve ventilation to the end of the 40-ft box cut when the continuous miner was starting the 40-ft slab cut and 20 ft into the slab cut, the blowing curtain was advanced from its 50-ft setback to locations 40-ft and then 8.5 m (28 ft) from the face. KEYWORDS: Face ventilation, Extended cut, Methane, Box cut, Continuous miner, Scrubber

By Causey J. Douglas

In 1988, at the request of the Bureau of land Management, the U.S. Bureau of Mines studied part of the 13,460-acre Owyhee Breaks Wilderness Study Area (OR-003-059) in order to evaluate its identified mineral resources. The study area is in Malheur County, OR, about 27 miles northwest of Jordan Valley. No mineral resources were identified in the study area during this investigation. There is an occurrence of jasper along Birch Creek and an associated occurrence of zeolite in some tuffs. In the northern part of the study area is an occurrence of bentonitic clay containing less than 40,000 tons. Much of the area is covered by landslide blocks, colluvium, earthflow deposits, and talus, composed of Tertiary-age volcanic rocks. The upper plateaus are capped by Tertiary-age basalt.

Jan 1, 1989

By S. J. Pearce

The need for a simple, very sensitive, and accurate method for the determination of benzene in blood and urine vas evident throughout a recent study of chronic benzene (C6H6) poisoning conducted cooperatively by the United States Bureau of Mines, The Barrett Company, and the producers of benzene. A combustion method which will be described in a later publication, and a previously described/ adaptation of Smyth's method were developed and used during that investigation. The adaptation of Smyth's method gave satisfactory results when dealing with exposure conditions that produced chronic poisoning in a comparatively few days, but it was time-consuming; and lacked the accuracy necessary for a study of the absorption, distribution, and fate of benzene in the body during exposure to threshold concentrations of benzene vapor in air. The combustion procedure was satisfactory from the standpoint of sensitivity but was cumbersome, intricate, time-consuming, and required the use of special and somewhat expensive Physical and chemical apparatus. Following the termination of this study of chronic poisoning, possibilities ides for developing better methods occurred, and these have been investigated by the Bureau of Mines with the aid of Relief Works Division personnel microcolorimetric method for the determination of benzene in air has been described recently.6/ The present report deals rich the adaptation of this new colorimetric method to the determination

Jan 1, 1936

By Donna D. Harbuck

The Bureau of Mines has investigated a process to produce titanium powder directly from titanium salts. If successful, such a process could lower the cost and increase the use of titanium. In this study, K2TiF6, K2TiF3, and TiF3 were reduced with potassium in the temperature range of 650° to 750° C. Under certain conditions, titanium powder 1.6 to 3.3 microns in size was produced. After leaching the product with a 0.1M HCl solution, powder impurities as low as 0.04 pct potassium and 0.28 pct fluorine were obtained. However, oxygen levels of over 1 pct and the frequent formation of insoluble byproducts demonstrate the need for further research to make the powder suitable for powder metallurgy applications.

Jan 1, 2011

By F. E. Cash

The Holmes Safety Association , organized and named in honor of the late Dr. Joseph A. Holmes , first director of the United States Bureau of Mines , has for its object the prevention cf accidents , the improvement of health conditions at work, in the home , and in public places , and the promotion of the general welfare of its members . As a means of preventing accidents and advancing health and safety , the Holmes Safety Association disseminates information , gives instructions on subjects related to safety , and promotes first -aid and other forms of protective and accident - prevention training . This organization is intended to work and cooperate in the closest possible way with existing mine or plant safety organizations in conducting educational , social , and recreational activities for the promotion of health , safety , and efficiency .

Jan 1, 1929

By Richard A. Watson, James A. Powell

A seismic system which utilizes in-mine geophones to detect trapped miners has been developed. Tests at the Bureau of Mines Safety Research Mine at Bruceton, Pa., and at two operating mines indicate such a system has a maximum detection range in excess of 1,000 feet. The system is field worthy and portable and requires less than 30 minutes to set up and check. Real-time detection is possible.

Jan 1, 1976

By R. Van A. Mills

[In previous contributions** the writer has called attention to important relations that faulting bears to the migration and accumulation of oil end gas. It has been pointed that favorably situated parts of oil and gas bearing, sands have been enriched by migration art segregation incident to faulting. The escape of water through natural passages such. as fault fissures has induced wide spread hydraulic currents through the beds toward these, points, of diminished pressure and these water currents, plus buoyancy hove contributed largely toward the migration of oil to favorable rock entrapments in the vicinity of the faults.*** The propulsive force of expanding gas has been one of the contributing causes for the hydraulic currents. Paradoxical as it may seem, the escape of gas with entrained oil through fissures has been on important factor In the migration, and accumulation of oil in many faulted areas. Compressed gas is the propulsive force by which oil generally moves to producing wells. It is also one of the propulsive forces by which oil has moved with or even ahead of water under conditions: of differential pressure brought about by faulting.]

Jan 1, 1922

By C. W. Owings

Two problems perplex many coal-mine operators and employees. Is coal-mine dust harmful to breathe; and, if so, is it possible to keep the concentration below the danger point? The medical profession is not unanimous in its opinion of the danger of breathing bituminous-coal dust, but there appears to be ample and increasing evidence that coal-mine dust can be harmful if breathed in large enough doses for long periods. The question of controlling the dust at the point of formation is still unanswered in the minds of many in the mining industry. However, results of limited studies conducted by the Bureau of Mines in 9 bituminous-coal mines indicate that a full-shift average exposure of workers should not exceed about 20 million dust particles per cubic foot of air (m.p.p.c.f.) and that concentrations can be held within this limit without too much difficulty. Furthermore, these studies indicated that an exposure in the neighborhood of 40 m.p.p.c.f. should not be exceeded for an individual operation and that it is possible to hold within this ceiling.

Jan 1, 1957

In the United States water pollution resulting from mining activities has long been recognized as a major environmental problem Mine drainage pollution results from many types of mining activities and includes both physical (i e , sedimentation) and chemical (i e , acidification, metal contamination, etc ) pollutants Active and abandoned surface and underground mines, mineral processing plants, mine and processing plant waste disposal areas, haulage roads, and tailing ponds are typical sources of mine related water pollution (130) One of the most serious pollution problems arising from mining activities is acid mine drainage resulting from the chemical reaction of sulfide minerals (commonly iron sulfides) and air in the presence of water Acid mine drainage is commonly associated with coal and hard rock mining areas in the United States In general the more serious and extensive acid mine drainage problems exist in the more humid coal regions east of the Mississippi River (11) In 1964 the U S Department of the Interior, Fish and Wildlife Service, reported that acid mine drainage adversely affected fish and wildlife habitat in 9,477 kilometers (5,890 miles) of streams and 6,062 hectares (14,967 acres) of impoundments in 20 states in the United States (64) Of the total affected waters, coal mining operations accounted for 97 percent of the acid mine drainage pollution reported for streams and 93 percent of that reported for impoundments In 1970 more than 19,308 kilometers (12,000 miles) of streams in the United States were reportedly significantly degraded by mining related pollution (130) Of the total affected kilometers, 16,920 kilometers (10,516 miles) or approximately 88 percent were located in the Appalachian coal region (Pennsylvania, West Virginia, Ohio, eastern Kentucky, Tennessee, Maryland, and Alabama) In addition, more than 965 kilometers (600 miles) of streams reportedly were degraded by coal mining in states in the Illinois, Western Interior, and Rocky Mountain coal regions The remaining portion of the stream pollution resulted from the mining of (1) copper (california, Montana, Nevada, New Hampshire, Tennessee, Virginia, and Wyoming), (2) lead and zinc (Colorado, Idaho, Kansas, Missouri, Montana, Oklahoma, and Tennessee), (3) uranium (Rocky Mountain States), (4) iron (Lake Superior iron region), (5) sand and gravel (all states), (6) phosphate (Florida and other states), (7) gold (Alaska), (8) bauxite and barite (Arkansas), and (9) molybdenum, gold, and other metals (Colorado) Abandoned mines and abandoned mine waste disposal areas contribute a large portion of the total pollution resulting from mining activities Numerous abandoned underground mines are located throughout the United States and many are discharging mine drainage pollutants In 1966 the U S Bureau of Mines estimated that more than 88,000 inactive and abandoned underground mines were in existance (126) A listing of these mines by state is presented in Table 1 0-1 More recent estimates indicate that this list is incomplete In Colorado alone there is

Jan 1, 1975

By V. R. Spironello

The Bureau of Mines is conducting studies of the slags related to ferrous technology to evaluate acceptable substitutes for the auxiliary flux, mineral fluorspar, in foundry operations. This work is directed toward the Bureau's goal of minimizing the Nation's dependence on scarce and critical minerals Comparative basic practice cupola (18-inch-ID) trials were made to evaluate a waste material called "used potlining," which contains significant levels of fluorine, sodium, and aluminum in various compounds. Used potlining is recovered from alumina reduction cells after its useful life, and was supplied by the Aluminum Co. of America (Alcoa) to the Bureau for evaluation. The material in the lump and pelletized form (with limestone) provided extremely fluid slags based on visual observation during cupola operation. No adverse effects were found on cupola performance, metal and slag chemistry, the environment, or mechanical properties of the castings produced. Fluorine recovery in the slag was equal to, or higher than, that of fluorspar; fluorine losses to the scrubber water and solids were lower. The acidity of the scrubber Hater was somewhat neutralized. No difference was observed in furnace-refractory attack, as determined by the level of magnesia in the slag and visual inspection. The recovery of sodium in the slag, presumably as the oxide, significantly increased slag fluidity, suggesting that less than equivalent fluorine may be required. There was no contamination of the gray iron by the aluminum from the used potlining. Used potlining was completely satisfactory as a substitute for fluorspar in cupola ironmelting.

Jan 1, 1981

By Hiram C. Draper

The Mining Division of the Bureau of Mines, in cooperation with the Obstacle and Demolition Branch, Engineer Research and Development Laboratories, Department of the Army, undertook some extensive tests to determine the effectiveness and limitations of using standard demolition-type shaped charges in underground Mining. The tests proved the shaped charge has no practical application in the functions of mining covered by this report. At an approximate cost of 0 per foot hole plus spall produced by the most efficient single shots with the M3 shaped charge, the cost is over 20 times that of producing a better hole with a rock drill. The concussion would prohibit its use in many mines, and the excess carbon monoxide gas liberated by the pontolite explosive would be an additional hazard when used underground.

Jan 1, 1948

By Phillip N. Yasnowsky

This Bureau of Mines report examines the percentage depletion allowance rate structure in relation to several criteria that are indicative of U.S. mineral import dependence. These criteria are the minerals considered as strategic and critical for stockpiling purposes, the ratio of reserves to forecast cumulative demand (1976-2000) for selected minerals, and the U.S. net import reliance as a percentage of apparent consumption (1978), also for selected minerals in general, it was Found that there does exist a direct, although not perfect, relationship between the percentage depletion allowance rates and the degree of import dependence as indicated by these three criteria. The higher percentage rates tend to he associated with those minerals for which the United States is, or will likely he, heavily dependent on foreign sources. In addition, a basic discussion of the mineral depletion allowance is provided, including numerical examples illustrating the computation of the allowance under several assumptions. Also, the percentage depletion allowance rates for individual minerals are tabulated.

Jan 1, 1980

By H. O. Poppleton, F. E. Block

This investigation was made to develop a method of preparing high - purity thorium metal in quantities up to 20 kilograms per batch . Several methods for the preparation , purification , and reduction of thorium tetrachloride are discussed . Thorium tetrachloride was prepared by chlorination of decomposed thorium nitrate or oxalate with carbon tetrachloride or phosgene . tion of the crude tetrachloride was achieved by multiple distillations or by filtration of the molten chloride . It was found that high - purity thorium metal could be prepared by sodium reduction of thorium tetrachloride if chloride of sufficient purity were available . Byproduct salts and excess reductant were removed by vacuum distillation , and the resultant thorium metal sponge was consolidated by consumable - electrode or fixed - electrode arc melting . It was demonstrated that metal prepared by this method could be fabricated into bar , rod , or sheet , at room temperature .

Jan 1, 1964

By G. R. Hopkins

According to reports received by the United States Bureau of Mines, Department of Commerce, as of January 1, 1929, there were 2,205 cracking units completed or being built in the United States, with a total daily charging capacity of 1,476,874 barrels. A similar survey of a year ago showed 2,334 units of 1,288,000 barrels total capacity. This indicates that despite a decrease in. number of units, there was a material increase in capacity. The year 1928 was, in general, an important one for the cracking branch of the industry. Gasoline consumption reached record levels, prices were higher than in 1927, and it is probable that in the late months of the year the cracking plants were operating very close to capacity.

Jan 1, 1929

By Jerry E. Olson

In 1985 the U.S. Bureau of Mines conducted a mineral survey of 68,458 acres of the Clan Alpine Mountains Wilderness Study Area (NV-030-102) which covers 196,128 acres in Churchill County, NV. Most of the area studied is underlain by Tertiary volcanic rocks. In the northeast corner of the study area, an upthrown block of Triassic sedimentary rocks partially extends into the area. The study area is probably part of a large eroded caldera. No major mines or active claims are within the study area. Field investigations included examination of workings in Starr Canyon, historical and recent mining activity near the mouth of Florence Canyon, other mining claims, and anomalous zones delineated by data from Great Basin GEM Joint Venture studies. No mineral resources were identified, but sample results indicate one significant mineralized zone situated along a northwest trend between the head of Starr Canyon and the head of Cherry Creek may contain precious metal resources. Further investigation of this zone is warranted.

Jan 1, 1987

By S. E. Khalafalla

The Bureau of Mines investigated variations in the activation energy for the carbon monoxide reduction of magnetite and ferrous oxide with respect to the state of aggregation of the oxide material. Reduction phenomena can only be satisfactorily explained by including an adsorption step in the reduction process. Summation of the values of the exothermic heat of chemisorption and the variable apparent activation energy for reduction yields a nearly constant value of about 50 kcal for either ferrous oxide or magnetite regardless of whether they are aggregated in pelletized form or coarsely crystalline particles.

Jan 1, 1965

Occupational illnesses are more difficult to identify than on-the-job injuries. Many illnesses related to occupational exposures may not be diagnosed until years after exposure; by that time, exposed workers may have changed jobs or left the workforce. Other approaches to identifying occupationally related illness are analysis of death certificate data (see chapter 2) and medical examination studies of workers known to have high exposures to hazardous agents. Figures 5-1, 5-3, 5-4, 5-6, 5-8, and 5-10 show, for each commodity, the percent of illness conditions reported to MSHA by nature of condition. Heart attacks that occurred on the job are reported without regard to work-relatedness. Figures 5-2, 5-5, 5-7, 5-9, and 5-11 show rates by year during 1986-1995 for selected conditions. Since there are many limitations on the accuracy of illness reporting, the frequencies and rates shown here should not be considered directly comparable across commodities. Figure 5-12 shows estimates for hearing loss by age among coal miners compared to a nonoccupationally noise-exposed population. These data come from a study by Franks [1996] of a group of audiograms obtained on coal miners by a commercial company. Using the NIOSH definition of hearing impairment, i.e., an average hearing threshold level for both ears that exceeds 25 dB at frequencies of 1,000, 2,000, 3,000 and 4,000 Hz, the figure shows that by age 30, more than 10% of miners suffer hearing impairment; by age 50, 90% of miners have hearing impairment. In contrast, only 10% of the nonoccupationally noise-exposed population suffer hearing impairment at age 51, and 50% of the nonoccupationally exposed population have hearing impairment at age 69. Figure 5-13 shows a similar analysis of commercial audiograms on male metal/nonmetal miners [Franks 1997]. At age 20, approximately 2% have hearing impairment using the NIOSH definition of hearing impairment described above. This increases to 7% at age 30, 25% at age 40, and 49% at age 50. In contrast, only 9% of the nonoccupationally noise-exposed comparison population have hearing impairment at age 50. Franks' analysis showed a different pattern for female metal/nonmetal miners; they developed hearing loss at the same rate as would be expected for a non-noise-exposed female population.

Jan 5, 2000