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By E. Morrice

High-purity lanthanum metal was prepared by electrolysis of La003 in a LaF3-LiF-BaF2 bath at 950° C. The requisite bath temperature for the deposition of molten metal was maintained by supplying the heat as current directly to the electrodes. A current efficiency of about 60 percent was obtained. The lanthanum nodules contained carbon and oxygen as major impurities. The total impurity content was from about 0.1 to 0.2 percent.

Jan 1, 1962

By C. Travis Anderson

 The general conclusion of earlier investigators was that the action of sulfur dioxide on manganese oxides of Cuyuna ores was not sufficiently pre- ferential to be attractive as the basis for a commercial process. Bradley4/ and his coworkers discarded it for leaching with boiling ammonium sulfate solution, and Sweet5/ used a baking operation to render the iron insoluble. These results were confirmed by the early tests in the present investigation, which were made on brown ores (Sagamore), using acid additions, because at that time the Technologic Committee on Manganese held the opinion that these ores constituted the major available reserve in the Cuyuna district. However, when it appeared that the black ores, or the formation in which they occur, were a possible source of a large tonnage of manganese, the use of sulfur dioxide and sulfuric acid leaching was again reviewed, and a satis- factorily preferential action on the manganese was found. It was originally thought that the use of sulfuric acid ahead of, or at least with, the sulfur dioxide simplified the process, particularly by preventing formation of dithionates. Removal of the phosphorus from the solution by neutralization with lime or fresh ore was suggested. The tests recorded in this report indicate that it is not practicable to use enough acid to prevent formation of dithionate and that the value of excess sulfuric acid is doubtful, particularly in regard to satisfactory manganese:phosphorus and manganese:iron ratios.

Jul 1, 1942

By A. S. Griffiths, J. E. Evans

Noise processing experiments with ELF (3 to 300 Hz) atmospheric noise and signals in the 40 to 80 Hz range are described. The primary purpose of the experiments was to record and analyze wideband ELF noise in order to design the noise processing portion of a receiver which minimizes the required transmitter power. The application of appropriate theory and extensive simulations led to a noise processor which consists of the following functions: (1) a compensating (or whitening) filter, (2) a prenotch filter clipper, (3) notch filters at frequencies of manmade interference (e. g., power lines), (4) a post-notch filter clipper, and (5) a phase-coherent linear matched filter. The nonlinear processing provides considerable gain relative to a linear receiver (i. e. , a receiver consisting only of a matched filter and appropriate whitening filters). It is convenient to measure sys tem performance in terms of an "effective noise level" which is equal to twice the received signal energy divided by the signal to noise ratio at the matched filter output. For example, the highest effective noise levels observed at 45 Hz with the nonlinear processor were about -134, -131 and -137 dB wrt 1 amp/m [Hz] using Saipan, Malta and Norway data, respectively, compared to 1 percent exceedance levels of effective noise for the linear receiver of about -115, 115 and -130 dB wrt 1 amp/m [Hz] respectively.

Jan 1, 1973

By Gerrit V. R. Goodman

Supplemental water sprays were placed along the sides of a continuous mining machine to improve suppression and confinement of the dust cloud under the cutting boom to re- duce downwind dust levels. Using a full-scale mock up of a continuous mining machine, preliminary work showed that these side sprays improved suppression of the dust cloud and redistributed this cloud under the cutting head. This led to reductions in dust levels around the machine and in down- wind airways for some positions of the mining machine. This testing also showed that side spray effectiveness was influenced by the distance from the fresh air ventilation device to the cutting surface, termed the ventilation setback distance. These sprays produced larger reductions in machine and re- turn dust levels at smaller setback distances than at larger setback distances. These side sprays then were installed in similar locations on a mining machine at an underground coal mine operation to evaluate their effectiveness for im- proving suppression and capture of dust by the flooded-bed dust scrubber. Although sampling could not be conducted successfully in the return, sampling around the mining ma- chine and at the machine operator showed that dust levels decreased with use of these sprays. Further analysis showed that these sprays were most effective at the smaller setback distances, a result confirmed by full-scale laboratory testing. Keywords Occupational Health, Dust Sampling, Coal Mining. Continuous Mining, Control Technology

By J. A. Zimrner, R. J. Tirnko

The roles of main mine fans in underground mines are to induce airflow and continuously re- move hazardous gases and dust. While most larger mines use multiple fans to accomplish these tasks, many smaller mines employ only a single fan. This paper concentrates on those mines having only one fan to provide ventilation needs. If this fan should cease to function, it is likely that methane concentrations will in- crease in some areas of the mine. As a safety precaution, Federal Regulations require that personnel must be- gin evacuating the mine within fifteen minutes after fan stoppage. Powered haulage can be used to transport workers to the mine portal as long as travel is through areas where hazardous levels of methane are not expected. To determine where methane will accumulate along haulageways during a fan stoppage, air samples must be taken at specific areas and analyzed for hazardous gases. During this study, procedures were developed for measuring methane levels along the haulegeways that are used to exit a mine following stoppage of the main mine fan. Methane levels were measured in four different mines at selected underground locations during four planned fan stoppages. In these mines the measurements taken only at the specified locations showed that, if workers had used electrically powered haulage to exit the mine following a fan stoppage, the methane accumulated along haulageways during fan stoppages would not have significantly increased the risk of an ignition.

By D. K. Ingram, G. L. Mowrey, T. R. Rehak

This paper summarizes fly rock and blast area security fatalities from 1989 to 1999 and examines the causative factors. Coal and nonmetal mining used about 43 billion pounds of explosives and blasting agents between1989 to 1999. A majority of this consumption was used at surface mines. Accident data indicates that fly rock and lack of blast area security were the primary causes of blasting related injuries in surface mining. Fatal injuries due to lack of blast area security were attributed to: failure to clear blast area; failure to follow instructions; inadequate guarding; inadequate blasting shelter; and unsafe location. Seven fatalities due to fly rock and lack of blast area security were reported in surface coal mines and six in nonmetal mines. Out of these, two fatalities (one each in coal and nonmetal mines) occurred outside the mine property. In the coal mining sector, two fatalities were attributed to fly rock, and five to lack of blast area security. In the nonmetal mining sector, three fatalities were attributed to fly rock, and three to lack of blast area security. Preventive measures include: ensuring that all personnel have evacuated the blast area during shot firing; using adequate blasting shelters for employees whose presence is required in the blast area; controlling and monitoring all entrances to the blast area; ensuring that the blast is properly designed, drilled, and loaded; and emphasizing education and training to enhance skill levels for implementation of engineering control techniques.

By Lloyd A. Morley, Robert Stefanko

This report has presented a literature review of explosion proof¬ing of coal mine electrical equipment. The international "state-of¬the-art" is an extremely difficult definition to quantify but, from the preceding paragraphs, it is evident the international community be¬lieves that it is represented by the International Electrotechnical Commission's Publications. Five questions were set forth during the beginning of this report. Each will be evaluated in light of the preceding discussion. 1. Can Schedule 2G specifications on explosion-proof containers be substantiated? Literature was found in the three main problem areas, surface temperature, mechanical strength, and explosion transmission, to determine this. Surface temperature requirements are adequate except for equipment that can normally overload, and the required intern¬al pressure does afford some margin of safety. However, in terms of safety, gap dimensions are about ten times smaller than that needed. 2. Is it possible to replace the Schedule's design requirements with performance specifications? Two primary areas were determined as mechanical strength and explosion transmission. As was mentioned, for present flange and gap standards, the 150 psig requirement is adequate. Furthermore, it is the authors' opinion that the level cannot be re¬duced if the present gap requirements are retained. The Schedule now requires that 16 tests be run, but the literature suggests that only from three to six examinations are necessary. Then by using the abso¬lute maximum pressure from these measurements or 150 psig, whichever is

Jan 1, 1974

By C. W. Owings, F. E. Cash

"Transportation of explosives in mines is extremely hazardous, and where electric haulage is employed the danger is intensified. Insulated mine-car couplings have been adopted by at least five companies in Alabama and Pennsylvania - and undoubtedly in other States - to prevent an electric current passing from a mine locomotive to a car or between care joined by this coupling. The need for such protection is recognized in the report of an explosion.""Four hundred kegs of black blasting powder had been loaded into four mine cars at the railroad, to be hauled to the magazine, upgrade, by a trolley locomotive. On starting, the motorman put sand on the rail and a grounded circuit passed through the hitchings and so exploded the powder. No insulation was used between the locomotive and cars."" When used on man trips the insulated coupling further serves the purpose of guarding the men against shock. Four couplings are described so that a clearer understanding may be obtained of the details of construction.ConstructionThe general principles of construction are similar in all insulated couplings. The piece containing the hole for the coupling pin is made of steel and the steel parts are separated by an insulating material, such as fiber or wood. The coupling is either rigid or semirigid to prevent the bumpers of the mine cars from coming in contact and to keep the cars insulated from one another at all times."

Apr 1, 1928

By Bruce K. Cantrell, Stephen W. Stein, David Hassel, Harvey Patashnick

The Mine Safety and Health Administration. Department of Labor, requires coal mine operators to measure compliance with federal re¬spirable dust exposure standards periodically using approved gravi¬metric samplers. However, the gravimetric approach, with its inher¬ent delays, cannot provide dust concentration data quickly enough to allow on-site correction of inadequate dust control strategies or re¬moval of personnel from harmful environments. Furthermore, alleged tampering with dust samples collected to determine compliance with standards prompted the Secretary of Labor to appoint a special Respirable Dust Task Group to study options to improve monitoring and control of respirable coal mine dust. The Mine Safety and Health Administration's Task Group recommended that the U.S. Bureau of Mines develop a fixed-site monitor that would provide continuous information to the mine worker and mine operator regarding dust levels and the status of compliance with the applicable respirable dust standard. In response to the Mine Safety and Health Administration's request, the U.S. Bureau of Mines is investigating several sensor tech¬nologies for continuously monitoring respirable coal mine dust. One of these technologies is the Rupprecht and Patashnick Co. tapered element, oscillating microbalance. The bureau is in the process of investigating the suitability of using this sensor in the high humidity and vibration environment of underground coal mines. Laboratory tests have indicated that, with modification, the sensor can meet the humidity and vibration requirements for underground coal mine use. Currently, the bureau is developing

By Lon D. Santis

This paper presents data and theorem to calculate the risk of experiencing undesirable lightning related events while blasting or while engaged in other lightning sensitive activities. The paper provides an overview of lightning hazards in blasting operations and a brief history of lightning related blasting accidents. Lightning continues to be the primary cause of premature initiations of explosives in mining, on average, over two such incidents are reported to the Mine Safety and Health Administration (MSHA) each year. The energy contained in lightning discharges and how this energy sets off explosives in mining is presented. Three categories of lightning warning methods: public media, lightning detectors, and atmospheric electrostatic field measurement are discussed. The remainder of the paper presents recently acquired data on the spatial characteristics of lightning development. This data is used to estimate the risk assumed by blasters under certain conditions. Risk estimations are made for electric and nonelectric blasting if persons are evacuated when cloud-to-ground (c-g) lightning approaches within a certain distance. For example, about 0.6% of all c-g lightning strikes have no other c-g lightning strikes within 25 miles in the previous 30 minutes. The paper shows that a typical blaster using nonelectric initiation in a high lightning density area with a 100% accurate lightning detector set to alarm at 25 miles would have a lightning caused unplanned detonation every 14,000 years

By A. B. Cecala

A cooperative research effort was established between the Tilden Mining Company LC, the United Steelworkers of America, and the National Institute for Occupational Safety and Health to lower respirable dust levels in an iron ore grinding and concentrator plant. This cooperative effort involved three field studies to evaluate different techniques to lower respirable dust levels. The greatest impact on lowering respirable dust concentrations throughout this facility was achieved through ventilation changes. The most significant improvement was realized by changing the ventilation profile throughout the entire facility. The ventilation to this grinding and concentrator facility was provided by approximately 40 roof fans operating in either the intake or exhaust mode. The operation of these fans was significantly changed in an attempt to pro-vide more of a directional flow pattern throughout the facility, as well as to more closely balance the intake and exhaust air volume. This change accounted for a 31 pct reduction in respirable dust levels in the primary grinding area of the mill. Another successful modification was to improve the sealing of a reclaim tunnel to the outside and by barricading the access point from the reclaim tunnel to the concentrator plant. This minimized the dust liberated in the conveyor tunnels from traveling through the reclaim tunnel and into the plant. These two modifications illustrate the impact that improvements in ventilation can have on lowering respirable dust concentrations in iron ore processing facilities.

To prevent injury to miners caused by violent whipping of mining machine trailing cables. Approach: The hydraulic cable controls are adjusted to reduce whip by visual reference of the cable sag to the height of the cable guide. How It Works: The cable sag is adjusted by visually estimating its height above the ground, at a specific reference distance behind the machine. This reference distance is measured horizontally back from the point where the cable leaves the cable guide. The Reference distance is 2H where H equals the height of the cable guide above the floor. See Figure 1. Cable sag should be less during rewinding than during unwinding. During cable unwinding, the cable height (at the refer¬ence distance) should equal 1/31-1. During rewinding, the cable height should equal ½ H. Field tests were made on several manufacturers' equipment after adjusting cable sag as above. Cable whip was greatly reduced for all, and whip was almost eliminated on a shuttle car equipped with a Joy Manufacturing Company 500108-104 cable reef and the newer (nonporous) shuttle valve. The following directions are for adjusting cable sag on a shuttle car equipped with a Joy Manufacturing Company 500108-104 Cable Reel equipped with the newer shuttle valve. Cable sag can be adjusted on machines equipped with other cable reels and valves by referring to the manufacturer's manual and making the appropriate cable valve adjustments.

Jan 1, 1976

Rank the dust knockdown (airborne capture) ability of six different types of water spray nozzles, Approach A fixed quantity of dust is released into a large, closed chamber in a laboratory. Water sprays are turned on inside the chamber and their effectiveness on the dust cloud is evaluated from the rate at which the dust disappears. This method better simulates dust suppression underground than methods tried earlier. The results of the laboratory test were confirmed by conducting tests on a full-scale mod-el continuous miner face where dust levels were measured in the return airway. Results of the Closed Chamber Tests The graph indicates that atomizing nozzles provide the best use of water for dust scrubbing. However, use of these nozzles is limited by their susceptibility to damage and clogging. Hollow-cone nozzles perform almost as well as atomizing nozzles. Test results also indicate that full-cone, venturi-assisted, and flat-fan spray cones are about two-thirds as effective as hollow-cone nozzles. The least effective were venturi nozzles designed for moving air. The most significant advantage of hollow-cone nozzles over other nozzles tested is reduced clogging due to larger orifice size. The hollow-cone nozzle used in the test and depicted by the graph was type BD-3 manufactured by Spraying Systems Co., Wheaton, IL. This nozzle is already used on many continuous miners. Other hollow-cone nozzles of

Jan 1, 1982

By L. D. Tracy

"Introduction In the course of the investigations by the Bureau of Mines into the various causes of coal-mine explosions, the fact that several gas explosions had occurred during or very soon after a mine was being un-watered, attracted the attention of the Bureau's engineers. The apparent coincidence was so marked that there appears to be an extra hazard present, whenever water, which has been standing against the face of the coal for some time, is suddenly removed either by natural drainage or by mechanical means.Actual Occurrences Case 1. - A typical illustration of this hazard is shown in a gas explosion which occurred in a mine in Central Pennsylvania. Four main entries, 50 feet apart with an average grade of 6 per cent, had been driven with the dip of the coal, and from these mains 7 pairs of entries, at intervals of 800 feet, had been turned at such an angle that their grade was slightly rising. Prom these latter pairs of entries, rooms were turned practically at right angles.The main entries had been driven for 4,500 feet and at the face there was 400 feet of cover. As far as could be observed, the roof was of sandstone and the floor of clay.The coal bed being mined was the Lower Kittanning, which has a thickness of about 4 feet. A typical analysis of the coal in that section is as follows:"

Oct 1, 1924

Develop a safe, efficient filter for removing diesel particulate matter (soot) from the exhaust of underground mining machines equipped with water scrubbers. Approach The Bureau of Mines and the Donaldson Company, Inc., jointly developed a low-cost, disposable, pleated-media filter (PMF) system. The system is intended for use on Part 36 permissible equipment or other machines equipped with water scrubbers. The PMF is installed downstream of the water scrubber to take advantage of the cool exhaust produced by the water bath. This demonstration system was tested on three Jeffrey 4114 Ramcars and a Wagner LST-5 scoop at Utah Fuel Company's Skyline mine near Scofield, Utah. Figure 1 illustrates a clean filter element being inserted into the canister on the Ramcar. How It Works The PMF system consists of a water trap, an optional over-pressure relief valve, filter canister, and PMF Under normal operations exhaust from a vehicle equipped with a water scrubber is heavily laden with water, especially on immediate startup of the engine. The water trap is designed to remove most of the water droplets from the exhaust before they enter the PMF, thus improving PMF performance. The over-pressure valve is designed to limit the exhaust backpressure by venting off some exhaust gas before the: filter. It is attached to the water trap upstream of the PMF. Figure 2 illustrates and shows a break out sectional view of the location of the PMF on the Ramcar.

Jan 1, 1991

This report describes magnetic field measurements in the Helvetia Coal Co. Lucene #8 Mine for purposes of deriving a mapping of the magnetic field strength covering the major haulageways which contain conductors. The measurements were performed by Terry S. Cory, P.E. under U.S. Bureau of Mines purchase order P0372716. Assisting in performance of the measurements were personnel from the Bureau of Mines, PMSRC, and Helvetia Coal Co. Acknowledgement is given to Engineer Tom Strong of Helvetia Coal Co. who accompanied the measurement team and who lended support in performing the measurements and in supplying valuable engineering information for use in evaluation of the results. The results of the testing at medium frequency show that coverage of the entire mine area containing conductors can be achieved employing wireless radio techniques whereby radio signals are coupled into and are carried by these conductors. These results confirm earlier qualitative testing of the Collins Mine Wireless Radios in this mine. These results, performed over the frequency range 71-2890 KHz, illustrate the effect of frequency on the radio propagation with the conclusion that the best overall coverage is obtained at frequencies approximating 1000 KHz. This report presents all the raw data and the reduced data in the form of magnetic field strength contour maps. Sufficient information is provided to enable independent reduction of the data. A summary of observations which can be made directly from the contour maps is given.

Jan 9, 1977

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

APPENDIX A - PNEUMATIC TRANSPORT OF FLY ASH 1. Introduction Two types of pneumatic transport of fly ash are critical to the success of (1) Transport of fly ash from the fly ash truck to the entrance to the borehole. Depending on the surface topography, this may be horizontal, decential and ascential. (2) Vertical downflow of fly ash through the borehole. All fly ash trucks have limited pressure with which they can pump the fly ash. Thus, the pressure drop in the fly ash hose will define the maximum length for pumping and consequently the maximum distance that the fly ash truck can be parked from the auxiliary blower. The same relationships describe the flow of the dilute fly ash-air mixture produced by mixing with the auxiliary air from the blower and thus define the selection of the pipe diameter. These are im¬portant considerations in the proper selection of the location of the passages to be sealed and the type of surface preparation required. The flow characteristics of fly ash down the borehole determine the selection of the minimum borehole diameter and the blower pressure. This appendix presents theoretical analyses of these flow regimes and summarizes the limited experimental data obtained during the field tests at Grant Town, described in Section 8.4. The analysis for the borehole flow is presented first as it is of greater interest to the program. This is followed by a discussion of the horizontal flow.

Jan 1, 1973

By D. Litton, H. Dobroski, J. G. Kovac

Since 1910, the U.S. Bureau of Mines (USBM) has investigated practical ways of dealing with the consequences of major fires and explosions in underground mines. The results of this research have had a significant positive impact on the mining community by enhancing mine workers’ chances of surviving an underground mine disaster. Today, the Bureau continues to conduct research in mine disaster mitigation. Much of this work has direct application to search and rescue situations, such as: emergency evacuation through smoke-filled or otherwise unbreathable atmospheres, locating and rescuing survivors from rubble piles, and fire fighting in confined spaces. Three USBM research areas are discussed: (1) Life Support -- This effort is directed toward research into and development of closed-circuit breathing apparatus for use in hazardous environments which are likely to be encountered in the aftermath of a mine disaster. (2) Trapped Miner Location -- A mine disaster may result in the entrapment of miners whose normal escape routes are cut-off. This research activity resulted in the development of transportable seismic technology that can be used to locate trapped miners. (3) Mine Fire Diagnostics -- This research involves developing practical techniques for remotely monitoring how the atmosphere inside a mine changes during a fire, in order to estimate the spread and severity of an underground fire. This information is critical in deciding how best to fight a mine fire, or whether it is safe to mount a rescue and recovery mission.

By J. H. Schuenemeyer

Consider a set of points, some of which are anomalous (larger than a specified cutoff value), located on a plane. Whether some or all of these points are clustered to form one anomaly or more or, alternatively whether these points are scattered at random, may be investigated by measuring perimeters of convex hulls. A convex hull is the smallest convex polygon that will encompass a group of points. (Examples of convex polygons are triangles, rectangles, and all other regular polygons.) A set of anomalous points is selected and the perimeters of the convex hulls of this set and all its subsets are measured and compared with tabulated values of perimeters for each subset size. For a given subset size consider those perimeters which are less than the tabulated perimeter. If the number of convex hulls is greater than the maximum number expected by chance, then the chance that any one of the observed-hulls-is a nonrandom cluster is the ratio of the observed number to the sum of the observed and the maximum number expected by chance. Otherwise, the points are evidently not clustered. If many sample points are anomalous, an alternate model defines various configurations of contiguous points and compares the observed number of configurations per unit area with the expected number. Applications are discussed in several fields of geology and geochemistry-including geochemical exploration surveys and heavy mineral spatial distributions--as well as in mining (dust control) and medical geography.

Jan 1, 1972

By Isaac A. Zlochower

A number of ignition incidents involving mining and farm equipment have illustrated the surprising danger of drilling, cutting, or otherwise penetrating sealed compartments or frames that are filled with metal scrap for ballast. The presence of chemically-reactive metals (or electrochemically-active pairs), such as zinc in galvanized steel, can produce hydrogen from moisture in the steel scrap, and the resulting pressure, due to the internally-generated hydrogen, can produce an easily-ignited gas jet when the sealed component is penetrated.