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Exposure to airborne respirable crystalline silica dust can lead to silicosis, a debilitating lung disease. On surface coal mining and construction sites, blast hole drills are notorious sources of airborne respirable dust that may contain significant amounts of silica. The drill operator and drill helper usually receive the greatest silica exposure compared with other occupations. As a result, many drilling operations have been, and still are, on more stringent dust standards. Drilling through various rock formations naturally presents a strong potential for silica dust generation for several reasons. First, drilling is a pulverizing process that generates large amounts of very small dust particles. Second, the bailing air used to flush cuttings from the hole leaves the hole at a very high velocity and can be difficult to contain. Third, many fixed shrouds used to enclose the area beneath the drill deck have a significant amount of leakage due to 1) gaps between the shroud and ground created by raising/leveling the drill, 2) gaps in the corner seams, and 3) tom deck shrouds. CONTROLS A dry dust collection system is typically connected to the drill deck to collect dust as the bailing airflow transports the cuttings (and significant amounts of airborne respirable dust) out of the drill hole. Deck shrouds are installed in an attempt to enclose the volume around the drill steel and prevent dust escaping. However, most deck shrouds are rectangular and constructed of four separate pieces of rubber belting attached to the deck. Because of this design, there is usually a significant amount of dust escaping from the open seams as well as the open area between the shroud and the ground. This dust can be a significant source of silica exposure to drill operators as well as other personnel downwind of the drill.

To pinpoint dust sources and to improve dust control on longwalls. Approach Use short-term gravimetric sampling to determine the severity of various dust sources, and to evaluate dust control techniques used in longwall mining. Short-term gravimetric sampling can be used to isolate dust levels produced by various dust sources. How It Works Traditionally, gravimetric samples have been collected over an 8-hour shift, yielding time-weighted, average dust concentrations. This method gives a good indication of the full-shift respirable dust exposure of underground workers, but is less than satisfactory for identifying dust sources, determining their severity, or for evaluating the effectiveness of dust control techniques. Short-term gravimetric sampling uses equipment available to all mine operators. Two individuals composing the survey team each collect multiple (three to four) gravimetric samples during selected segments of the mining cycle. Multiple samples are necessary to insure accuracy, and to obtain a valid average measurement of the respirable dust concentration when sampling for short periods of time (typically 20 to 30 minutes). The gravimetric instruments may be carried in a sampling package or in a "sampling vest." A fishing vest with four large pockets can be used for this purpose. The sampling pumps are carried in pockets and the sampling head assemblies arc hung across the front of the vest.

Jan 1, 1982

By Edward D. Thimons, Jay F. Colinet

Underground coal mining operations in the United States continue to increase productivity as mining equipment and practices are improved. Unfortunately, increased production also results in the potential for increased respirable dust generation and worker exposure. In response, US operations are applying basic controls at elevated levels and looking to emerging technologies in an effort to better control respirable dust levels. Ventilating air and water sprays remain the basis of dust control strategies for both longwall and continuous mining operations, and the level of application for these controls continues to increase. In addition, new technologies are emerging that have the potential to further reduce dust levels. The National Institute for Occupational Safety and Health (NIOSH) has been conducting research into methods to optimize existing control technologies and evaluate emerging control technologies. This paper will summarize control technologies routinely being used in underground coal mine operations, as well as provide a review of new controls that are being pursued.

Provide a rapid, reliable means of warning underground miners of a fire or other emergency. Approach An ultalow-frequency electromagnetic signaling system was designed, breadboarded, and tested at various under around mines. How It Works Current fire warning systems for underground mines, such as stench, audible alarms, and messengers, arc slow, unreliable, and seldom achieve total mine coverage. An ultralow-frequency electromagnetic fire warning alarm system with true through-the-earth signaling capabilities was developed to solve these problems. The system was originally designed for high-back room-and-pillar mines where stench systems are unusable due to the low velocity of mine air flow. However, the system has an application to all underground mines.

Jan 1, 1988

By Arthur L. Murray

"Putting safety over , " using the accepted meaning of the word " Safety " as the elimination of personal injury , resolves itself into the prevention or disassociation of a combination of two distinct circumstances . Opportunity for accidents is afforded by conditions that are likely to cause injuries , but such injuries are effected only when the human body is placed in a position to be injured . As will be discussed later , in mining , as in most other industries , the degree of safety experienced depends upon the disassociation of these two circumstances , first , by making working conditions as free from hazards as possible , thus affording the minimum opportunity for accidents to occur , and secondly , the training of employees to recognize dangerous conditions and adopt measures to protect themselves and their fellow employees against injury . The responsibility for preventing accidents rests upon every person employed in an industry from the directing head down through the individual workers , and the safety of that industry will be proportionate to the extent that each member appreciates and accepts his individual responsibility . Hence , safety becomes decidedly a personal equation . Whether the personal equation will be so applied as to result in the greatest freedom from accidents , however , depends largely upon the initiative of those directing the industry . Putting safety over in a small mine presents the personal equation in a more intensified manner than the same endeavor in a large mine . Large mines , owing to their size and financial standing, can usually main ta in and support an effective safety organization with one or more directors who devote all their time to the supervision of safety work . Most small mines with a limited number of employees and limited capital can not afford and are not justified in supporting a paid safety organization , and must depend upon the close cooperation of their working force in maintaining safe working conditions . On the other hand , if proper supervision is exercised the small mine has in some respects advantages not afforded by the large mine . The limited workings in a small mine should afford less opportunities for dangerous conditions to arise and permits more frequent inspection of the entire mine . The small working force permits more latitude in the selection of employees known or believed to be either safe workers or amenable to safety educational work. Likewise , a small working force facilitates the carrying on of safety educational work and allows a closer personal contact between the superintendent and his employees .

Mar 1, 1923

By Carl Rampacek

Recent research by the Bureau of Mines has demonstrated that the segregation process has merit for treating oxidized and mixed oxide-sulfide copper ores. The process comprises heating the crushed ore with salt and coke or other carbonaceous materials at about 700° C. to produce fine flake copper, which then is recovered by conventional copper-flotation methods. Bench-scale laboratory tests of a number of oxidized and mixed copper ores assaying 0.78 to 5 percent Cu gave copper recoveries of 73 to 96 percent. The flotation concentrates assayed 21 to 76 percent Cu, depending on the ore being treated.

Jan 1, 1959

By S. M. Runke

An ever-increasing demand for beryllium and beryllium alloys has directed attention to the milling of low-grade domestic deposits as a possible means of supplying part of the Nation's ore requirements. The United States generally produces less than 10 percent of its annual supply. For example, new supply in 1953 was estimated at about 9,250 tons, of which the United States imported 8,500 tons. Domestic production was only 750 tons.2/ Since record high prices for beryl in 1952 and 1953 did not greatly increase domestic product ion, the United States must develop mechanical beneficiation processes to use low-grade deposits and reduce dependence on foreign sources

Jan 1, 1954

By Ralph L. Rinehart, Wils L. Cooley

This paper summarizes recent experiments with grounding systems. Problems and potential hazards related to in-mine grounding systems are discussed. The monitoring of trailing cable ground conductors and testing of commercially available ground monitors are discussed.

Jan 1, 1975

By W. C. Hudson

"The McLeod sand pits, on the northeast side of the Little Ocmulgee River in Wheeler County, Ga., opposite Lumber City in Telfair Co., were examined by the Bureau of Mines under its war program of Investigation of Critical and Essential Minerals. The pits are about a quarter of a mile above the bridge, which is half a mile above Lumber City. Mrs. A. T. McLeod of Lumber City owns the land, including the pits. The property was inspected by an engineer of the Bureau of nines on March 8, 1945, on recommendation of Capt. Garland Peyton, director, Division of nines, Mining, and Geology of Georgia.The Mcleod pits are at the northwestern extremity of a mile-long series of old pits that were worked from about 1900 until the 1920's. The burning of the spur railroad bridge connecting the pits with the Southern Railway at Lumber City stopped mining operations. The pits on the south-east, or opposite, side of the Glennwood Road from the McLeod pits were first worked by F. L. Hinson and later, in 1921, by Mrs. n. H. Mobley. The glass sand was shipped to Tallapoosa, Ga., and Chattanooga, Tenn., where it was used in the manufacture of bottles for soft drinks. Some of the sand was used as molding and construction material. The sand was mined by hand shoveling it into wheelbarrows, which were unloaded on freight cars. The pits were partly refilled with overburden, so that it is impossible to estimate even roughly the amount of sand excavated.Analyses of samples of glass sand made years age3/ and later in 19404/ roughly check those made by the Bureau of Mines laboratory, except that in the former the iron oxide content usually was greater, attaining a maximum of 0.72 percent.The sand pits are in a valley slightly more than a quarter of a mile wide that lies along the northeast side of the Little Ocmulgee River. The land is either flat or marked by ridges only a few feet high. . A rather thick growth of scrub trees covers most of the valley. The surrounding country consists of gently rolling farm lands. The altitude of the valley is not known, but, judging by its distance from the seashore, it probably is about 200 feet. In addition to the Glennwood highway, which crosses the valley, several old sand roads lead to the pits."

Apr 1, 1946

By S. H. Katz, J. J. Bloomfield

Fires in zinc dust have sometimes given particular trouble owing to their resistance to extinguishers and the liability of explosions . Similar problems , notably with aluminum dust* , have previously been subjects of investigation by the Bureau of Mines .

Mar 1, 1922

By F. W. Smith

This paper is based largely on a study of experimental data obtained by the Bureau of Mines in its comprehensive 25-year survey of the carbonizing properties of American coals. Although the Bureau was interested in and conducted carbonization research-from time to time ever since it was organized in 1910 (1),4/ no systematic studies of the coke-, gas-, and byproduct-making properties of American coals were undertaken until 1927, when the American Gas Association appointed an advisory committee (2) to cooperate with the Bureau in developing equipment and techniques to obtain-data for the accurate assessment of the behavior of coals on carbonization. It was found, in general, that small-scale laboratory tests were unsuitable for the complete evaluation of the coking properties of coal; hence, larger pilot-plant-scale equipment was designed and used (3). It was decided that the scale of the test should be large enough to determine both the yield and quality of the products and yet small enough to maintain adequate control of the process variables (4). These considerations led to development of a carbonizing retort and furnace-of 80 to 200 pounds of coal capacity, suitable for operation at various temperatures up to 1,100° C. (2,0120 F.) and equipment for recovery and measurement of gas and byproducts. This apparatus and the standardized procedure for its operation became known as the Bureau of Mines-American Gas Association (EM-AGA) method or retort (5).

Jan 1, 1955

Improve the safety of mine workers by developing a sensitive ground-fault relay system capable of detecting and isolating low level ground faults and thereby minimize the danger of electrocution. Approach Inadvertent, direct contact with energized conductors in underground coal mines is a major cause of electrocutions. Although relay systems designed to protect workers against such fatal accidents do exist in some industries, there are no effective ground-fault-sensing relay systems that address the special problems presented by power systems designed for U.S. mines. The Bureau of Mines conducted research to design and construct a sensitive ground-fault relay for use with low-voltage, alternating current (ac) mine electrical systems. Such a relay, sensing current leakage or faults in an electrical system, would send a trip signal to a circuit interrupting device which would then shut down power.

Jan 1, 1986

By Donald H. Mullen, Walter R. Storms

"INTRODUCTION The Copper Flat area of the Central mining district, Grant County, N. Mex., has been visited by numerous engineers 4/ of the Bureau of Mines and geologists 5/ of the Federal Geological Survey. In December 1944 the Bureau. 6/ proposed that geophysical work be done in that area in order to locate favorable sites for future company exploratory and development work. This geo-physical work was begun early in 1945 but never fully completed because of insufficient funds. The engineers who made the survey recommended that more work be done, especially to locate the bottom of the Copper Flat laccolith by resistivity-depth surveys. All known minable zinc-lead ore bodies had been found above this laccolith in the Copper Flat mine, but it was thought that other minable ore deposits should occur in favorable limestones beneath it. The geophysicists also recommended core drilling beneath the laccolith.In the summer of 1946, following some mapping by S. G. Lasky of the Federal Geological Survey, funds were appropriated for a Bureau of Mines project in the Copper Flat area. The project was completed in June 1947. 8/"

Apr 1, 1948

By Walter R. Storms

This paper , which describes the mining methods and costs at the Atwood copper mine in the Lordsburg ( Virginia ) Mining District of Hidalgo County , N. Mex . , is one of a series being prepared by the Mining Division of the Bureau of Mines on mining practices , methods , and costs in various mining districts of the United States . The mine and surface plant are situated in the west half of sec . 7 , T. 23 S. , R. 18 W. , about 3 miles by road southwest of the center of Lordsburg , near the old abandoned townsite of Valedon ( see fig . 1 ) . The main line of the Southern Pacific Railroad passes through Lordsburg , as does the paved eastwest U. S. Highway 70-80 . A spur line of the Southern Pacific ends near the mine . A good graded road connects the mine with Lordsburg . The following pages present a brief history of the district , describe the geology , and outline methods of prospecting and exploration, including sampling and estimations of tonnages and values . Development, and mining methods are explained , and transportation , ventilation , drainage ,. safety measures , and organization are described . The wage scale and costs of development and mining comprise the corrcluding sections of this circular .

May 1, 1949

By Ray J. Holmquist

"INTRODUCTION The Copper King or Red River copper mine was examined on December 13, 1942, by the Bureau of Mines at the request of Richard Kelly of Santa Fe, N. Mex. The examination was made to determine whether the expenditure of funds for rehabilitation work necessary to make the workings accessible for examination would be warranted.As a favorable report was made, the workings of the Copper King mine were opened and sampled under the direction of the author. The portal of the Copper King adit was opened first. Considerable rehabilitation was necessary in the first 50 feet of the workings, but the remainder of the drifts and crosscuts were sufficiently open to permit surveying and sampling.An attempt was made to open the Waterbury atilt, which was reported to be about 30 feet east of the Copper King portal, and to crosscut the ore body nearly to its southern border. However, slide rock and mine dumps had completely obscured the portal of this adit, and no opening into it could be found or made.Work on the project was started on September 27 and vas completed on November 6, 1943."

Apr 1, 1947

By Joseph A. Perry

One goal of the Bureau of Mines is to develop technology tp insure a dependable supply of minerals to the United States. To support this goal, the Bureau's Albany Research Center has modified a commercial atomic absorption spectrophotometer to rapidly determine trace levels of mercury by cold-vapor atomic absorption spectrophotometry. Such diverse materials as ores, mill products, stream water, sediments, and flue dust have been analyzed. A very high dynamic range of 0.2 ng/ml to 1 µg/ml of mercury in solutions is routinely analyzed by this instrument.

Jan 1, 1981

By Robert F. Randolph, Dana C. Reinke, Richard L. Unger

Purpose The NIOSH Hearing Loss Simulator is a software training and communication tool for promoting hearing loss prevention. It allows a user or trainer to demonstrate the effects of noise exposure on hearing without experiencing an actual noise-induced hearing loss. Estimates of the effects of different levels of noise exposure are based on the American National Standard Determination of Occupational Noise Exposure and Estimation of Noise-Induced Hearing Impairment, otherwise known as ANSI S3.44. This standard specifies the predicted hearing loss for noise-exposed populations of individuals based on risk factors that include gender, age, sound levels (in A-weighted decibels or dBA), and years of exposure. Algorithms specified in the standard were derived from empirical studies of populations that had no exposure to loud noise and other populations that had experienced various levels and durations of noise exposure. This manual explains the major objectives that can be addressed with the simulator and training scenarios that can be applied to real-life, real-worker scenarios. The majority of this guide explains the simulator's functions in detail. Simulator users are encouraged to read this manual while learning how to run the software. [ ] Training Objectives The main objective of the Hearing Loss Simulator is to increase motivation for taking effective hearing prevention action by demonstrating simulated noise-induced hearing losses. [The Simulator can also help teach the following facts about hearing loss. Hearing loss is affected by noise levels. Hearing loss worsens as the noise exposure duration increases. Hearing loss can become permanent. Hearing loss makes it harder to hear what others say. Most hearing loss is not caused by age. Speech is made up of both low and high pitch sounds. Hearing loss due to noise makes it harder to hear high pitch sounds. Hearing loss due to noise has less of an effect on hearing low pitch sounds.]

Jan 3, 2008

By H. P. Greenwald

About mid-December 1936, the safety director of a large coal corporation visited the authors at the Bureau's Experimental coal mine to discuss a rock-dust barrier he had invented primarily for use in trackless entries of coal mines. The rock dust in this device was carried in its original paper containers and means were provided for ripping these open so that the dust might be scattered in the path of an explosion. The inventor termed the device a "bag barrier", and this term has been adopted in the present paper for convenience. At that time the device was in an early stage of development, and the inventor felt that the barrier should be tested to determine whether it had enough promise of being successful to justify further development. The matter was taken under consideration and finally three tests were made during the week of February 15, 1937. It was concluded that while the device did stop an explosion in two of the three tests, it was much loss effective than ordinary rock dusting, and that too few data were obtained to permit direct comparison with tests of other barriers. Apparently, the conditions under which the device could, be successful were somewhat limited, out the limits could not be defined without additional tests.

Jan 1, 1938

By L. B. Berger

"Additions to List Published in Information Circular 7444 NEW APPROVALSThe following respiratory protective devices have been approved by the United States Department of the Interior, Bureau of Mines, since Information Circular 7444 was issued (March 1948):Gas Masks Approved Under Schedules 14, 14A, 14B) 11+D, and 14E Type N: Universal Gas MasksUniversal gas masks with filters that afford respiratory protection against smoke from ordinary fires and limited respiratory protection against dusts, fumes, mists, and fogs but do not afford respiratory protection against the toxic smokes of warfare.Willson WUG-Nl universal gas mask. Approval BM-1443, issued to Willson Products, Inc., May 25, 1948.Bullard universal as mask. Extension of approval BM-1443, issued to E. D. Bullard Co., January 12, 19 9.Supplied-air Respirators Approved Under Schedules 19 and 19A Type C: Air-line Respirators4. METCO air-line respirator. Extension of approval BM-1920, issued to Metallizing Engineering Co., Inc., December 8, 1948.Type CE: Abrasive Blasting Helmets, Hoods, or Masks9. M.S.A. abrasive mask. Approval BM-1920, issued to Mine Safety Appliances Co., April 30, 1948."

Apr 1, 1949

By L. W. Kelly

The purpose of this paper is to describe several methods that have been employed in successfully recovering roof bolts in Indiana, Illinois, and western Kentucky coal mines, the States where successful roof-bolt recovery was started. As far as is known, the first bolts were recovered in a mine in western Kentucky in January or February 1951. In April 1951 a meeting was held at that mine to discuss the recovery of roof bolts. The meeting was attended by A. D. Sisk, former Chief, Kentucky Department of Mines and Minerals; and L. W. Kelly, Federal Bureau of Mines; and officials of the coal company. Inasmuch as roof bolting was in its infancy, the thinking regarding roof bolts at that time was on the problem of getting them in, not getting them out; consequently, the thought of recovering them was revolutionary. The subject was discussed at length from all angles, and it was finally agreed that, if certain safeguards were taken, no agency represented at the meeting would oppose the practice. That this decision was sound has been proved, as thou-sands of bolts have been recovered in the Middle West without a lost-time accident. Recovering roof bolts is a simple operation; consequently, no complicated equipment had to be designed or built for this purpose. However, about 5 years ago, officials of the Traux-Traer Coal Co. conceived the idea and constructed a mechanical device for recovering bolts that has been very successful and has been copied widely in this area. This device will be discussed in detail in part II of this paper.

Jan 1, 1958