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By Joseph M. Singer

Having established that sodium chloride reduces the incendivity of explosives, the Bureau of Mines studied the effect of sodium nitrate in reducing ignition hazards. Gallery experiments showed that sodium nitrate reduced the incendivity of certain explosives to 8 percent natural gas in air but increased their incendivity to coal dust predispersed in air. Laboratory experiments using hot jets from explosions of stoichiometric mixtures of methane-oxygen-nitrogen showed that both sodium chloride and sodium nitrate reduced the incendivity to methane, to mixtures of coal dust and methane) and to coal dust. The difference between the gallery and laboratory results with respect to coal dust is attributed to temperature-time effects.

Jan 1, 1967

By Arden D. Fugate

This work was conducted to determine a feasible process for converting siliceous fluoride offgases to a commercially usable product. The offgases were generated by pyrohydrolytic defluorination of low-grade fluorspar in a gas-fired rotary kiln, and fluorine was collected as a hydrofluoric-fluosilicic acid. A silicon-free fluoride solution for further processing was then produced by neutralizing the acidic scrubber solution with anhydrous ammonia, silicon being separated as orthosilicic acid. Ninety to ninety-nine percent of the fluorine originally present remained in solution as ammonium fluoride. Silicon was also separated from synthetic fluosilicic acids, having F-to-Si weight ratios ranging from 3.50 to 14.3. The solutions below a ratio of 4.06, the F-to-Si ratio of H2SiF6, containing dissolved silicon were desiliconized as completely as those containing less than the stoichiometric quantity of silicon. An electrolytic-grade cryolite was recovered from the ammonium fluoride solution by reacting with either sodium aluminate or alumina trihydrate and sodium hydroxide. A product containing 97 to 100 percent of the fluorine, represented by Na3A1F6, was recovered, and 94 to 99 percent of the theoretical yield was realized.

Jan 1, 1963

By G. Dale Coe, Will H. Coghill

The " periodic pincer " herein described fills a need for a device to control the rate of flow of a wet ore pulp through an orifice . Two uses of the periodic pincer to be discussed are on classifiers and on a wet ore feeder . Although the immediate necessity that brought about this device was for better operation of a miniature hydraulic classifier , in connection with an investigation of iron- ore concentration being conducted by the Federal · Bureau of Mines , with the cooperation of the University of Alabama , the device has promise of a wider field of application . In the iron - ore work , the need became so acute for a nonchoking , uniform - delivery classifier spigot that development of a suitable device was imperative .

Apr 1, 1944

By William G. Pariseau

A small displacement-small strain finite element technique utilizing the constant strain triangle and incremental constitutive equations for elastic-plastic media that are nonhardening and obey a Coulomb yield condition has been applied to the analysis of gravity flow initiation in a V-shaped hopper containing a powder under lunar environmental conditions. Three methods of loading were examined. Of the three, the method of computing the initial state of stress in a filled hopper prior to drawdown by adding material to the hopper layer-by-layer is superior (as expected). Results of the analysis of a typical hopper problem show that the initial state of stress, the elastic moduli, and the strength parameters have an important influence on material response subsequent to the opening of the hopper outlet.

Jan 1, 1971

By Ronald T. Mayerle

In-1992, the U.S. Bureau of Mines conducted a mineral investigation of the Anderson Mountain study area, including RARE II area 4-942, in Lemhi County, Idaho. The 7,340-ha study area lies within the Salmon National Forest about one kilometer north of the old mining town of Gibbonsville (pop.: 100). The eastern boundary of the study area is formed by the crest of the Bitterroot Range. The crest also serves as the continental Divide, and as the border between Idaho and Montana. The study area lies within the Gibbonsville Mining District, an important past producer of gold from lode and placer deposits. Since the 1870's, several hundred claims for both types have been located in the study area. Thirty-six current (1992) lode claims and two patented claim groups (one lode and one placer) are wholly or partially in the study area. No placer claims are current. In all, twenty-seven lode and five placer properties in and adjacent to the study area were investigated. Workings on the properties included 2 caved shafts; 36 caved adits; 8 open adits; 120 small pits, cuts, and trenches; and 4 large dozed cuts.

Jan 1, 1993

By E. H. Denny

"IntroductionOn May 27, 1927, a coal-dust explosion occurred at the Palagua No. 5 mine of the Victor American Fuel Company, Delagua, Colorado, resulting in the loss of even lives and in and in considerable damage to the main slope and to several overcasts the explosion did not extend into the mine working where 125 additional men were employed but escaped uninjured. It is believed that the saving of these 125 men and the evidence of large property loss were due in a large measure to coal-dusting and of other sanity measures taken by the coal company management. A number of features connected with the explosion and mine safety practice seem worth the attention of the mining public and grateful acknowledgment is made to the Victor American Fuel Company for its aid in assembling the data herein contained."

Nov 1, 1927

By Alla D. Mah

The energies of combustion of two carbides of tungsten and two carbides of molybdenum were measured , and the corresponding standard heats of combustion were derived . The results are as follows : WC : AH298.15 ( combustion ) = -285,940 ± 250 cal /mole , W₂ C: AH298.15 (combustion ) = -490,660 ± 400 cal /mole , Mo₂ C : AH298.15 ( combustion) = -439,350 ± 600 cal /mole , MoC : AH298.15 ( combustion ) = -269,800 ± 1,000 cal /mole . The combustion heats were combined with the heats of formation of the corresponding metal trioxides and carbon dioxide to obtain the following heats of formation : WC : AH298.15 ( formation ) = -9.6 ± 0.4 kcal /mole , WC: AH298.15 ( formation ) = -6.3 ± 0.6 kcal /mole , Mo₂ C : AH298.15 (formation) = -11.0 ± 0.7 kcal / mole , MoC : AH298.15 (formation ) = -2.4 ± 1.0 kcal /mole . The heats of combustion and formation of MoC are tentative .

Jan 1, 1963

By Arnold O. Tanner

The recession that took hold of the domes-tic mining industry in 1981-82 finally abated somewhat in 1987, resulting from increases in many commodity prices, especially in the metals sector, and from continuing success in lowering operating costs. By no means was the work finished; the mining industry was in a sense entering a new era. The struggle for survival was still very evident for many companies and various commodities, but increasing productivity and profits were accompanied by indications that these trends were more long term than short term. Raw nonfuel minerals produced in the United States during 1987 had an estimated value of $26.3 billion, an increase of $2.9 billion over the 1986 value. This is the fifth consecutive year that the value has increased. Except for a decrease in 1982, the value each year has increased since 1971, or 15 of 16 years. The value of raw metals production increased by an estimated 28%, an impressive improvement since the drastic fall in 1982. Industrial minerals growth was comparatively flat, with an estimated in-crease in value of 0.1 %, continuing a trend of the previous 2 years. Metal mine production dropped considerably in 1982 and maintained its resultant lower level until 1987, when production significantly recovered.

Jan 1, 1989

By A. U. Miller

For many years Illinois has been one of the leading coal producers in the United States and as such its safety record has compared very well with the other large coal producing States , both in tons produced and millions of man -hours of exposure per fatal accident . ( See Table 25 in Bureau of Mines Bulletin 293. ) During the 10-year period from 1917 to 1926 , inclusive , the average production in the United States per fatal accident was 278 , 109 tons . The aver age for the State of Illinois for the same period was 409,249 tons . Illinois produced 450,464 tons per fatal accident, and in 1928 produced 390,630, tons , or an average of 419,721 tons for the 12- year period from 1917 to 1928 , inclusive . In 1927 During the year 1929 , the shipping mines of the State made a decided improvement in their record over any previous year . Table 1 shows the monthly production and the tons produced per fatal accident . During 1928 and 1929 safety work was actively carried on in Illinois . Safety meetings were held with mine officials , representatives of the State. De partment of Mines , and the United States Bureau of Mines . At these meetings mine hazards and accidents were discussed and remedies suggested for : their elimination in the future . It is believed that first - aid training was to a considerable extent instrumental in reducing accidents and in making the good safety records in Illinois during 1928 and 1929. During these years ( as well as in 1926 and 1927 to a somewhat less extont ) en intensive rirst-aid training campaign was con ducted in Illinois by the officials and members of the United Mine Workers of America , coal companies, State Department of Mines and Minerals , and the U. S. Bureau of Mines , Every first -aid class was made a safety meeting ; where accidents and general safety were discussed freely while teaching first aid. During this time , anproximately 25,000 persons were trained in first aid, and 17 coal companies were issued certificates for having 100 per cent of their employees. trained in first aid. Since January 1 , 1926 , more than 40,000 have received first -aid training in and around Illinois mines , and including those who received training previous to this date , it is believed that at least 90 per cent of the miners in Illinois have received first -aid training . This state ment is based on the fact that the labor turnover in Illinois is not large .

Apr 1, 1931

By M. S. Oudenhoven

The Bureau of Mines conducted an investigation to determine the theoretical stress distribution in the vicinity of explosively expanded rock bolt anchors independent of their bolts. Plane-strain solutions applicable to this problem were obtained by combining the field pressure with the uniform pressure that would be produced by vertically placed anchors having 2-, 3-, and 4-foot spacings. High rock stress which would be produced by an anchor was localized, as would be expected from St. Venant's effect, and increased as the field pressure decreased.

Jan 1, 1967

By Charles L. Kimbell

The final 26 tables of this chapter, tables 25-50, extend and expand the statistical series on production that was started in the 1963 edition of the "Area Reports: International" volume of the "Minerals Yearbook" and that was subsequently updated and expanded in the 1965 and 1967-89 editions. Continuing the practice started in 1989, a column has been included in each of these tables providing a 5-year average for 1986-90, inclusive. This should provide a clearer picture more rapidly of the role of each major producer over the 5-year period. The listing order of major producers, however, continued to be, as in past years, in descending order of rank in the year of review, 1990. With the inclusion of silver and uranium in the 1988 edition of this chapter, this group of tables now includes each of the crude minerals that ranked from 1st to 19th in 1983 terms of value of their output (as well as four others of lesser rank). These 23 crude mineral commodities accounted for 93% of the estimated value of world crude mineral production in 1983. In addition, world output of five key downstream products-aluminum, steel, cement, nitrogen in ammonia, and refined oil-are included because of their significance as products.

Jan 1, 1993

By G. A. Smyres

The Bureau of Mines conducted laboratory studies to determine the feasibility of chlorine-oxygen leaching for treating low-grade zinc sul-fide flotation concentrates. Recovery of zinc sulfides by flotation from complex fine-grained sulfide ores is substantially higher in low-grade bulk sulfide concentrates than in the high-grade cleaned concen-trates required for smelter feed. However, there is no commercial process in the United States for the treatment of low-grade bulk zinc sul-fide concentrates. Leaching experiments using reactors of 500-mL and I-gal capacity were conducted on a bulk concentrate containing 19.3 pct Zn, 35.6 pct Fe, and 39.4 pct S. The effects of pressure, temperature, and percent solids on extraction were investigated. The chlorine-oxygen leaching procedure showed promise for treating the concentrates. Zinc extractions of 95 pct or more were obtained by leaching at 50 pct solids in the temperature range of 1000 to 1200 C. Zinc extractions by leaching with chlorine followed by oxygen at reactor pressures of 50 to 100 psig were independent of pressure.

Jan 1, 1985

By C. P. Lazzara, R. A. Franks, G. F. Friel, J. C. Edwards, J. J. Opferman

A series of four coal combustion experiments was conducted at the National Institute for Occupational Safety and Health's (NIOSH) Pittsburgh Research Laboratory (PRL) in the Safety Research Coal Mine (SRCM) to evaluate the response of fire sensors to a small 0.61 m square smoldering coal fire which transitions to flaming combustion in the presence of diesel emissions. An optical path smoke sensor alarmed earlier than a point type diffusion mode ionization smoke sensor which alarmed prior to a CO alert value of 5 PPM above ambient. The presence of steady state diesel emissions resulted in a decrease in the optical smoke sensor analog output voltage signal by less than 1.4 pct for the three coal fire experiments in which a diesel engine was operating, whereas the ionization smoke sensor output decreased between 10.8 and 26.7 pct after the initial surge of the diesel engine. A commercial diesel discriminating fire sensor did not alarm for a fire in the one experiment for which it was used. The results of the experiments demonstrated that an optical path smoke sensor might be used to detect a coal fire under the experimental conditions considered of starting a diesel engine followed by a slowly developing coal fire.

By J. F. Barkley

The work covered in this report was done to meet the requests from many Government agencies for information on alleviating sludge difficulties in No. 6 (Bunker C) fuel-oil storage tanks. Accumulated sludge at times caused serious loss in tank capacities; pumps became overloaded or lost suction; strainers often required very frequent cleaning; fuel-oil heaters in some instances became fouled and inefficient; and gobs of sludge that passed the strainers interfered with good combustion. The requests also included questions regarding the usefulness in general of oil "additives" for preventing sludge and the relative merits of the many trade-named additives being marketed. Realizing that preventing such difficulties would result in substantial savings to the Government, an investigation was begun with the limited funds avail-able. Although various claims are made for No. 6 fuel-oil additives other than preventing sludge, only an investigation as regards the storage tank-sludge problem has been possible.

Jan 1, 1955

By M. H. Kline

The Chestatee mine is one of several well known pyrite deposits in Georgia that are reputed to carry appreciable quantities of copper with the ore. The deposit is? in Lumpkin County on the Chestatee River, 6 miles northeast of Dahlonega (fig. 1). Old records and reports indicated the probable existence of an extensive unmined ore body, but the mine is inaccessible at present. The Bureau of Mines, after studying old maps and records, decided to cor8-drill along the strike of the lense beyond the limits of the indicated old workings in an attempt to extend the possible reserves. The advantageous location of the property indicates that it could become an economic source of pyrite to be used for the manufacture of sulfuric acid. Iron sinter resulting from the roasting of the ores could be sold at a premium in the Birmingham, Ala., area, and the copper content could be extracted to help replace the nation's depleted resources of this metal.

Jan 1, 1949

By H. D. Jacobs

The Federal Bureau of Mines, as part of a program to insure future raw material needs for the iron and steel industry, undertook research to beneficiate the oxidized taconites from the western Mesabi range in Minnesota. The data presented were obtained by applying the Bureau-developed selective-flocculation/cationic-flotation process to the second of three oxidized taconite samples. These three samples are representative of an estimated 10 billion tons of ore analyzing 30 to 40 pct iron. The experimental work was performed in a 900-lb/hr pilot plant. Treating the ore sample (36.1 pct Fe) with the Bureau's process produced commercially acceptable concentrates averaging 63.5 pct Fe and 4.3 pct SiO2, with an average iron recovery of 84.6 pct.

Jan 1, 1980

By J. C. Edwards, C. C. Hwang

A Computational Fluid Dynamics (CFD) program was used to model buoyancy induced Product-Of-Combustion (POC) spread from experimental fires in the National Institute For Occupational Safety And Health (NOSH), Pittsburgh Research Laboratory (PRL), safety research coal mine. In one application, the CFD program was used to predict spread from fires in an entry under zero airflow conditions. At a location, 0.41 m below the entry's roof at a distance of 30 m from the fire, the measured smoke spread rates were 0.093 and 0.23 m/s for a 30 and a 296 kw fire, respectively. The CFD program predicted spread rates of 0.15 and 0.26 m/s based upon the measured fire heat production rates. Based upon a computation with [c3h3] as the hydrocarbon fuel, a predicted 5 PPM co alert time of 70 s at a distance of 30 m from the fire is to be compared with the measured alert time of 148 s. In a second application, the CFD program was used to analyze smoke flow reversal conditions, and the results were compared with visual observations of smoke reversal for 12 diesel fuel fires. The CFD predictions were in qualitative agreement with visual observations of smoke reversal.

[In presenting this list of permissible explosives and blasting devices, the Bureau of Mines desires to call attention to pages 17 and 23, outlining the conditions in use under which, and only under which, the explosive or blasting device is permissible. In view of publications recounting trade practice favoring the use of a blasting device without stemming, particular emphasis is placed upon condition 4 on page 17 and condition 2 on page 23. An explosive or a blasting device enumerated in the permissible lists of thin Bureau is not permissible in use unless it is properly confined with clay or other incombustible stemming.]

Jan 1, 1941

By Charles W. Huggins

To determine the nahcolite and dawsonite content in oil shales, the Bureau of Mines compared X-ray diffraction, infrared spectroscopy, thermal methods, and a previously published method by Smith and Young based on the selective solubility of sodium compounds. The Smith and Young method and a new method based on the weight of carbon dioxide produced by thermal decomposition are recommended for determining nahcolite. X-ray diffraction and the Smith and Young method are recommended for determining dawsonite. X-ray diffraction, infrared spectroscopy, and differential thermal analysis were useful for identifying other minerals in the samples.

Jan 1, 1973

By P. J. Coleman

Research in the field of mining safety and health in the United States plays an important part in protecting the lives of miners. The National Institute for Occupational Safety and Health (NIOSH) Mining Program conducts surveillance, studies and developmental work aimed at improving the safety and health of miners. With recent reviews of the Mining Program by the National Academy of Sciences and the Mining Program response (NIOSH, 2008), the importance of setting goals, conducting high quality engineering and scientific research and evaluating the outputs, outcomes, relevance and impacts of these projects has been reemphasized. Surveillance of reported injuries is a first step in deciding on research directions and in designing specific projects. Groups of injuries often share features and attributes that suggest common causes and may respond to similar preventive efforts. Identifying groups of injuries also serves to prioritize intervention efforts. The Mine Safety and Health Administration (MSHA) Accident and Injury database (MSHA, 2008) provides individual case reports of mining injuries, illnesses and certain no-injury accidents (events such as roof falls that stop mine production or miners? activities for more than one hour). This database is an indispensable resource for researchers and stakeholders needing information on the statistics of these events. From an epidemiological perspective, research projects target groups of miners at risk due to specific patterns of work, equipment, mine settings and the management of safety and health in their mines. Incidence rates are provided by the MSHA data for selected variables, such as surface/underground location, standard industrial classification and state. While incidence rates are the preferred measure for all variables, denominators are not typically available; for example, to more clearly under-stand the data about injury by occupational type, it would be necessary to conduct demographic surveys. A current survey of the demographics of the mining industry should be complete by 2010, which will allow incidence rates to be developed for a number of variables such as age, occupation and experience. This survey will provide the first update of its kind since the first survey was conducted in 1985.

Jan 1, 2010