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By Victor E. Kral

"INTRODUCTION The Segerstorm-Heizer property was examined by engineers 3/ of the Bureau of Mines in May and June 1942 and Mach 1943. As a result of these examination, the Nevada State Department of Highways,constructed 9.3 miles of graveled road under the mine access-road program. A magnetometer survey was made by the Geophysical Division 4/ in October 1943, and as a result the Mining Branch set up and conducted a core-drilling,project. Work on the deposit started May 24, 1944, and was suspended on July 31, 1944, but was resumed on December 4, 1944 and continued until completion on March 27, 1945.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as it, primary objective the more effective resource to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploration work, and prepares the final report. The Metallurgical Branch, R. G. Kinickerbocker, chief analyses samples and performs beneficiation tests."

Mar 1, 1947

By Edward Thomas

In 1947 the Bureau of Mines, as an accident-prevention measure, decided to advocate the adoption of roof bolting (suspension roof supports) in coal mines where it appeared to be applicable. Subsequent experience has disclosed that the applicability of this support is more general than was first suspected; moreover, comparison of the accident records of mines before and after adoption of the roof-bolting method shows results that more than justify the effort and funds expended. The industry has responded enthusiastically, because roof bolting proved to be not only an accident-prevention measure but also one to increase productive efficiency. In some instances this increase in the productivity of men and machines has been almost incredible and has led many mining men to conclude that through some hocus-pocus they can now cast aside many or all of the time-proven rule of good mining practice. If this tendency is not counteracted, it could easily result in an increase of roof-fall accidents, which may outweigh the benefits of roof bolting and discredit an innovation in roof control that shows great promise of materially reducing our mining accidents. From an economic standpoint it may represent the margin between profit and loss in many mining operations. The purpose of this manuscript is not to propose an inflexible code or set of rules but to summarize the experience to date as a guide for those who have the responsibility for the installation and inspection of roof bolts. This experience consists of approximately 250 investigations of roof failure in which roof bolting was involved either directly or indirectly. It should be pointed out that many of these failures were controlled, occurring during experimental periods, and comparatively few of the accidental failures actually resulted in personal injury, yet a significant number represented potential hazards.

Jan 1, 1951

By H. R. Babitzke

The purpose of this investigation was to evaluate the potential of columbium-hafnium alloys as structural materials for use at elevated temperatures. The work described in this report was conducted to determine the properties of columbium-hafnium alloys and to select the more promising ones for further improvement. Properties determined in this report were machinability, hardness, workability, tensile strength, and oxidation resistance. Ten ingots, ranging from 100 percent columbium to 70 atomic-percent hafnium, were prepared and subjected to tests. The test results showed that the alloys with 33 and 50 atomic-percent hafnium were superior in workability, strength, and oxidation resistance. For the alloy series tested, the strength and hardness values increased with the increasing hafnium content. Maximum values were reached with 50 atomic-percent hafnium. The oxidation resistance was poorest at the 1 atomic-percent hafnium level but improved with increasing hafnium content through 70 atomic-percent. Eight of the ten ingots were fabricable at room temperature. The two remaining ingots, those with 5 and 10 atomic-percent hafnium, required hot-working.

Jan 1, 1962

By Charles D. Litton

Laboratory experiments were conducted to determine the responses of a prototype smoke detector and a commercially available photoelectric smoke detector to smoke particles generated from various combustion sources. The prototype smoke detector combines optical scattering measurements with ionization chamber measurements in order to reduce/eliminate nuisance alarms due to the presence of airborne dusts or diesel exhaust particles. The commercially available smoke detector is designed for use in harsh environments where airborne dust represents a major problem due to both nuisance alarms and detector contamination. In the experiments, the responses of the two detectors were measured when exposed to smoke particles from the exhaust of a diesel engine and from a variety of fire sources, including wood, coal, styrene butadiene rubber, and No. 2 diesel fuel. For the solid fuels, data were obtained for both smoldering and flaming combustions. This report describes the experiments, their results, and the use of these results as they apply to early-warning fire sensors capable of the rapid and reliable detection of fires in atmospheres that may or may not be contaminated by either airborne dust or the products produced from diesel engines.

Jan 1, 2008

By F. C. Turin, K. M. Cornelius

1. INTRODUCTION Underground mining in the USA has undergone significant change in the past 20 years. Two key elements have been increased mechanization and a more educated work force in spite of these changes, many jobs continue to be labor-intensive and repetitive in nature. They entail tasks that, performed over time, can take a toll on the soft tissues and joints. The problem may be compounded by an aging mining workforce. In 1996 the mean age of the coal mining work force was 45 years and the median total years of experience was 20 (NMA 1998). As a person ages, the body resilience to chronic wear and. tear is reduced, which may cause a worker to pay an increasingly higher health price for performing the same task. Mining companies, like many others, are becoming more aware of cumulative effects to the worker as reports of these types of injuries rise. . Conducting a job analysis is an important step when considering a job redesign or modification to reduce worker cumulative trauma exposure. A basic approach to job analysis is to examine the types of aches and pains reported, the tasks performed, and work site conditions. The US Bureau of Mines (USBM) conducted an evaluation of roof-bolting tasks performed at an underground coal mine concerned about early warning signs of cumulative trauma. This evaluation will comprise the primary focus of this chapter. The approach used for the roof-bolting race study may be applicable to other work environments. 2. FUNDAMENTALS OF CUMULATIVE TRAUMA EXPOSURE Musculoskeletal injury is a term used to describe a wide range of soft tissue disorders that affect the nerves, tendons and muscles. Common examples include lower back pain, tendinitis and carpal tunnel syndrome. The majority of these injuries are not the result of sudden mishaps, but usually develop gradually from repeated wear and tear. Symptoms may not appear immediately, but can take weeks, months or even years. Symptoms may result from many types of activities, performed at work or at home, and it is often difficult to attribute there to a single event. In fact, it is more common to identify factors that may have contributed to the development of the condition. The terms repetitive strain injuries or cumulative trauma disorders (CTD) have been commonly used to refer to disorders that have occurred due to work-related activities. Three main risk factors contribute to CTD: force, repetition and awkward postures. Any one or combination of these may contribute to the development of CTD. Therefore, the design of equipment in conjunction with the required tasks should be evaluated when attempting to reduce these risk factors. Examining the layout of the work area to help identify tasks which may contribute to cumulative trauma is necessary. The following list (Putz-Anderson 1988), describes ergonomics concerns that, overall, should be minimized at the work area: • Crowding or cramping the worker: a work area layout may unnecessarily constrain movements of the worker. • Twisting or turning: placement of tools and materials may require the worker to twist the spine to fulfill the requirements of the job. • Repeated reaching motions: the layout of the work area may require the worker to lean to reach and grasp the necessary tools and controls. • Misalignment of body parts: the arrangement of the work area may require the worker to frequently have one shoulder higher than the other or have the neck or spine bent to one side. While many of these concerns are a function of equipment design and environmental conditions, making workers aware of these issues may help them to adapt their work habits to reduce risk of injury. Additionally, this information is useful when conducting an ergonomic evaluation of a work area and associated tasks. 3. UNDERGROUND MINING ENVIRONMENT The underground mining environment is a unique challenge. It is more difficult to develop controls for an underground mine site as compared with a factory setting where equipment and facilities can be more easily designed to reduce worker force, posture and repetitive exposures. In an underground mine, workers are required to perform labor-intensive tasks that often cannot be avoided due to environment constraints. The dynamic nature of the environment does not allow easy implementation of mechanical assists to reduce force exposure. Many of the tasks performed by workers are repetitive. Restrictive work areas due to low ceiling height, low lighting levels and large pieces of equipment cause workers to perform these tasks in postures that are not desirable. Designers of underground mining equipment can control how a machine will function, but not the environment in which it will be used, Hazards in an underground mine cannot be completely removed by redesigning the system. There are many hazards and information sources that must be continually monitored by workers including their position in relation to large pieces of mobile equipment and unpredictable geological anomalies. Thus, immediate dangers may take priority over awareness of ergonomic considerations while performing a job. 4. CASE STUDY OF UNDERGROUND ROOF BOLTING 4.1. Roof Bolting and Cumulative Trauma Exposure In an underground coalmine, after an area is mined it is necessary to support the roof to keep it from collapsing. Since 1950, the primary method for supporting the mine roof has been installation of roof bolts. Long bolts installed into the roof compress the layers of strata achieving a uniformly distributed support anchorage. Roof bolts, typically 6-8 feet long, are installed by workers using large roof-bolting machines. There are different types of machines

It was decided to demonstrate the use of latex as a soil sealant by irrigating three small plots at Lanse coded 03A on the west of Brown's run, 3C on the east of the stream, and SB, an area on the spoil bank. Earlier plans to sprinkle latex on twenty acres of the side were abandoned because of easement difficulties. On the basis of results from laboratory soil columns and small plot experiments at Lanse, Naugatex J-3471 was the latex of choice. The irrigation system consisted of plastic pipe (two inch size) for the main line from the water meter to the irrigation area because of lower price and ease of handling. Because the municipal water supply was limited to 20 gpm, low-volume 14V-LA-TNT Rainbow sprinklers were specified with low angle 20° 3/32 inch nozzles to reduce wind effects. At the expected nozzle pressure of 50 psig, each sprinkler covers a 56 foot diameter area at a delivery rate of 1.64 gpm. Each of the three test areas was covered with twelve sprinklers, six used with water alone as a control area and six used with latex and subsequent water spraying. One-quarterturn inlet valves were positioned on the main lines leading to each area. Flow to the treated and untreated areas was set at 10 gpm by Dole flow control valves in the' main entry lateral to each of the six sprinklers. To avoid the use of dilution tanks, a Moyno pump operated by a 1/2 HP, 1140 rpm 5:1 reducing drive was used to deliver 1/2 gpm 48% latex for mixing with 10 gpm water. A 3500 watt gasoline generator provided power for pump and light. Latex was applied at night to take advantage of the lower evaporation and higher humidity. Neutron gauge access tubes were placed in orthogonal arrangement in the areas that were irrigated, with four tubes in the section that were sprinkled with latex and four tubes in the untreated irrigation section in each of the three locations. Each tube, five and one-half feet long and sealed at one end with a plug welded in place, was inserted five feet into the ground in a cored hole. In each irrigation area, the left section of six sprinklers spread the dilute latex while the right section sprinkled the same amount of water to serve as a control plot. As shown in Figure 7 each sprinkler has a 56-foot sprinkling diameter at 50 psig design water pressure. The sprinklers are 30 feet apart on the laterals and 35 feet apart between the laterals. The access tubes (coded AT on Figure 7) were placed in comparable spots on the two sections of each area, so that four soil moisture measurements on the two sections could be compared. Bouyoucos resistance blocks (BB) were also placed in areas 03A and 3C at one, two and three foot depths, but not on the spoil bank area.

Jan 1, 1972

By Frank J. Susko

The U.S. Bureau of Mines has developed a computer model to describe a flotation process. Coal data from conventional flotation has been converted to a simple, two-parameter kinetic model developed by Reuter and van Deventer (1,2)3. Each set of coal data was represented by two constants, a and ß, and an average flotation rate. The success of the model was demonstrated when the calculated and experimental recoveries showed good correlation. The two-parameter model allows complex data to be defined much more efficiently than traditional knowledge-based models.

Jan 1, 2010

By R. L. Schmidt

Research conducted over the past 20 years in France, Great Britain, and the United States on the use of the large-hole burn cut has established cer¬tain advantages for this system. Advantages include longer pull and more complete fragmentation from blast rounds. However, research is needed to establish a set of parameters for optimum performance. As part of the Bureau of Mines Advancing Mining Technology for Marginal Resources program, the Twin Cities Mining Research Center, Twin Cities, Minn., acquired a horizontal rotary drill capable of boring holes up to 24 in. in diameter. This was used for a series of underground experiments at White Pine mine, White Pine, Mich., during 1973. Exceptional results were obtained with a 12-1/4-in void hole that yielded up to 18 ft of pull in a 10- by 20-ft drift, Fragmentation was excellent, and the compactness of the muck pile facilitated loading.

Jan 1, 1975

By A. B. Hooker

Since man first mined underground, there has been need for adequate illumination; this need has never been fully supplied. At first, suitable lamps were not available. Gradually they have been developed, but along with that development the need for better and better lamps has continued owing to the following conditions and factors: 1. Increasing hazards from gas and dust ignitions. 2. The speeding of operations with mechanized mining, which necessitates greater visibility. 3. A demand that cleaner coal be loaded, which requires higher levels of illumination. 4. The cost of compensation for injuries that has created a demand for better illumination and safer lamps. Use of better lamps has been retarded by: 1. Prejudice and resistance to change on the part of the workers in some districts. 2. The cost and upkeep of the lamps. 3. The present types of lamps, while a great improvement over the old lamps, do not entirely fulfill the requirements for a safe and efficient light for underground workers.

Jan 1, 1938

By A. B. Hooker, L. C. IlsLey

The greatest hazard of early mining was from explosions of methane ignited by open lights . With the advent of safety lamps and forced ventilation this hazard was greatly reduced until the application of electricity to modern mining not only multiplied the sources of gas ignition but the accompanying , machines and haulage systems increased the amount of explosive dust , through which a methane explosion is more liable to become a major mine disaster , and thus greatly furthered the need of adequate ventilation to keep down the concentrations of methane . Adequate ventilation is still the best preventive of such explosions . However , even with a well laid out and controlled ventilating system the amount of air passing through entries and rooms is liable to vary within wide limits because of open doors , falls of rock , or other accidental causes . The percentages of methane under normal conditions should therefore be kept so small that they will not be increased to explosive proportions by short interruptions in ventilation . Mine ventilation and methane detection are inseparable safety precautions . The increasing importance of ventilation necessitates more accurato determinations of the methane concentrations throughout the mines . This paper discusses in detail some of the steps in the development of methane detection and specially notes the more accurate detectors now available . One of the earliest means of detecting methane was by a candle . About 1835 , John Buddle , Sr. , a noted mining man of his period , when questioned by a Parliamentary Committee as to the safety of using candles , replied :

Jun 1, 1933

By Robert A. Jankowski

The U.S. Bureau of Mines, in cooperation with the Mine Safety and Health Administration (MSHA) and the mining industry, has identified and demonstrated the effectiveness of several improved face ventilation techniques for longwall mining systems. These include the following: identifying improved techniques for measuring face ventilation parameters on longwall sections, installing curtains at the intake end of the longwall face to maximize usage of the primary airflow, identifying optimum face airflow rates for maximizing dilution effects, and coursing the primary face intake from tailgate to headgate to minimize outby airflow contamination. Application of these techniques throughout the mining industry should reduce the health hazard associated with excessive exposure to respirable coal mine dust.

Jan 1, 1993

By H. H. Schrenk, L. B. Berger

"INTRODUCTION The Bureau of Mines frequently receives requests for information and advice regarding the equipment necessary for establishing laboratories for the analysis of mine atmospheres. Such requests are made by mining companies, State mining departments, and other agencies concerned with the safety of mining operations. In many instances it is desired to install a complete laboratory, which will necessitate purchase of suitable gas-analysis apparatus and all the minor but important accessory equipment needed to carry on this type of work. Although publications that describe methods and techniques applicable to the analysis of mine atmospheres are available, it is not within the scope of such publications to give detailed information on laboratory equipment or design. Persons unfamiliar with laboratory practices and gas-analysis procedures may find it difficult to decide upon the proper equipment for their particular needs and to itemize the various accessories that must be obtained to set up a complete laboratory.The purpose of this circular is to discuss the different types of equipment that may be used in the analysis of mine atmospheres, with particular regard to the application and limitations of each type. Information on the various accessory equipment needed in a laboratory for the analysis of mine atmospheres is given also, and suggestions on laboratory design are included. As much of the necessary equipment may be obtained from laboratory supply houses, the information should aid in arriving at estimates of the cost of proposed laboratories.The procedures involved in the analysis of mine atmospheres are not described; such information is contained in publications referred to in this circular."

Feb 1, 1948

By William D. Mayercheck, August J. Kwitowski, John R. Bartels

This report discusses the Bureau of Mines' efforts to develop partial protective structures for operators of low-coal shuttle cars. In coal seams 48 in high or less, full-coverage canopies are generally difficult or may be impossible to implement on high-speed face equipment due to the restrictions they impose on the operator's vision and comfort. Lim- ited coverage is one alternative that provides an acceptable level of operator protection in thin-seam applications where conventional full- coverage canopies cannot be used. Three possible limited-coverage de- sign scenarios (roll bars, sliding canopies, and flip-top canopies) were designed, fabricated, and evaluated for low-coal shuttle cars. All three designs were determined to be feasible and desirable for low-coal shuttle car application.

Jan 1, 1987

By Parviz F. Rad

The Bureau of Mines conducted groove cutting experiments in marble, lime-stone, granite, and quartzite with a 7-inch disk cutter under a normal thrust of 7,000 lb. The values of muck weight per unit length, specific energy, cutting coefficient, and groove depth for each of these rocks were determined for groove spacings ranging from 0.1 to 4 inches, and from these results the values of optimum and critical spacing were computed" The results indicate that compressive strength may be used to predict some of the cutting characteristics of the independent grooves. Considering all the cutting characteristics, particularly those for the interacting grooves, Shore hardness, coefficient of rock strength, and torsional velocity correlate with cutting characteristics better than do other physical properties. Some of the field applications of the principles established in this report are identified.

Jan 1, 1974

By Thomas H. Dubaniewicz

Thirteen miners died as a result of 2 explosions in the Jim Walter Resources No. 5 mine near Brookwood AL in September 2001. Both explosions were ignited in intake air entries, and both were probably ignited by electrical equipment. With few exceptions, permissible equipment is not required in intake air entries of US underground coal mines Researchers with the National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory. studied the electrical equipment ignition sources for the Brookwood and other w disasters to develop recommendations for preventing similar disasters Adherence to National Electrical code® requirements for flexible cords installed in hazardous (classified) locations may have prevented the second massive Brookwood explosion. The 30 CFR Part 7 requirements for battery assemblies should be reevaluated, taking into consideration United Mine Workers of America recommendations and the Zone 1"increased safety" standard requirements for battery assemblies, Class 1 Division 2 or Zone 2 explosion protection techniques are recommended for intake air equipment so that they do not present a methane air ignition source under normal operation before mine power is shut down during emergencies Battery powered circuits intake air that are likely to remain energized during emergencies should be protected by more stringent protection techniques, to protect rescue/recovery personnel. Index Terms -Class 1 hazardous location, mine explosion, flexible cord, battery assembly, permissible equipment

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

In studies of mine and tunnel ventilation conducted by engineers of the Bureau of Mines , various smokes are used to determine flow of air , direction of the currents , and the rate of mixing . The instrument for generating streams of sulphur trioxide (SO ) smoke , shown in the drawing herewith, has been found helpful , convenient and practicable for such purposes ; it is also especially useful in some places where fire for generating smokes is not permissible . The apparatus consists simply of a glass tube containing fuming sulphuric acid on granular pumice stone , attached to a rubber syringe bulb . When a squeeze of the bulb blows air through the tube , a stream of dense white smoke evolves, which follows and makes visible the air currents . The tubes after preparation are hermetically sealed to prevent deterioration . When ready for use , they are easily broken open at a file scratch for the purpose on both tips , and inserted into a rubber nipple at the bulb . Sometimes it is of advantage to attach them to a longer rubber tube leading to the bulb . Tubes of the size shown (about 1/2 inch outside diameter by 5 inches long) are usually sufficient for the needs of a day . Thereafter they cease to fume because the acid absorbs moisture from the air and looses its effectiveness . Smaller sizes of tubes and larger have been made , but the size shown has proved most practicable . Immediately after a person has finished using a tube it should be buried or disposed of in a place where it will not be touched by shoes or clothing, or come in contact with wooden floors , furniture , or metals , because the acid , which will eventually leak from the tubes , is highly corrosive . -- Reports of Investigations , Department of the Interior , Bureau of Mines .

Jul 1, 1923

By Basil Dimitriades

Five recently developed methods for determining nitrogen oxides in automotive exhausts have been evaluated from the standpoint of accuracy and applicability in current exhaust studies. Results showed that methods requiring conversion of nitric oxide to nitrogen dioxide as a part of the analytical procedure are subject to errors introduced by the instability of NO2. The extent of some of these errors has been determined and procedures have been developed to minimize undesirable influences. On the basis of the results obtained from this study, recommendations are made regarding procedures for batch type or continuous measurement of nitrogen oxides in exhaust streams.

Jan 1, 1968

By D. B. Dow

This report on methods employed for dehydrating oil-field emulsions, is the second of a series prepared as a result of a study of oil-field emulsions recently completed by the writer. The first paper2 dealt with the factors responsible for the formation of emulsions. A third paper will discuss the physical chemistry involved in the formation and resolution of such emulsions. In the early development of the oil fields of Pennsylvania, no emulsion troubles of any consequence were encountered, nor to any serious extent in the oil fields of other Eastern States: However, with the development of fields west of the Mississippi in Oklahoma, Kansas, Texas and California, where heavier oils of different characteristics were found, the problem of dealing with cut oil soon became of great importance.

Jan 1, 1925

Reduce workers' dust exposure by capturing airborne coal and quartz dust generated by a continuous mining machine. Approach Install a water-powered scrubber system operating at 1,000 psi on the boom of a continuous miner at the conveyor throat. Dusty air from the face area is drawn through the scrubber and cleaned air discharged into the return. How it Works Most coal mines use exhaust face ventilation to send fresh air over the miner operator and contaminated air behind the line curtain to the return. The problem with exhaust ventilation is that the line curtain should be within 10 ft of the face for maximum effectiveness. If the line curtain is not extended properly, or water sprays for dust control are poorly installed, dust rolls back towards the operator. An effective way of removing this dust is with a scrubber mounted on the mining machine.

Jan 1, 1988

By John J. Sammarco

As part of a project to automate coal extraction, computer control of a continuous mining machine test bed has been developed and tested by the Bureau of Mines. A computer system and control software were developed for accurate positioning of the conveyor elevation and swing, stabilizer jack, gathering head, and shear elevation. Tramming actions are also controlled by the computer. The computer system was designed to access data from sensors installed on a continuous miner and to interface with the existing control circuits of the miner. Testing in free space was used to characterize the operation of the machine. From this information, control algorithms were written and stored in the computer. The ability to control each function of the continuous miner with a high degree of accuracy and stability was successfully demonstrated in a series of tests in free space and in mining a block of simulated coal. In the mining of simulated coal, the cutting drum was instructed to position the shearer at the top of the block and shear down to the bottom under closed loop control. The cutting drum came within 0.27 in of the top and within 0.49 in of the bottom of the block for this shearing test.

Jan 1, 1988