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By J. M. Singer

Methods are proposed for predicting concentrations of nitrogen oxides and carbon monoxide in the combustion gases of flames, specifically of lean, stoichiometric, and rich propane-air flames. Calculations are based on kinetic and thermodynamic theory. These theoretical data are compared with concentrations observed experimentally downstream of flat grid-type burner flames (approximately 25,000 Btu/hr) that were used to simulate gas appliances such as water and space heaters. Air pollutant concentrations are also computed for (1) flames chemically perturbed by recycling flue gases into the primary fuel-air mixtures; (2) flames thermally perturbed by cooling the burned gases at different rates; and (3) flames perturbed by combination of these two effects. In general, experimental and computed concentrations agree to within a factor of 2 to 7 with the experimental values always being higher than the theoretical. The theoretical analysis indicates that cooling the primary flame by recycling cold flue gases (with and without excess air) reduces the relative emission of nitric oxide and increases emission of carbon monoxide if the flame stoichiometry does not radically change. Cooling rates of about 5,500° to 10,000° R/sec starting at about 3,500° R generally suffice to prevent nitric oxide concentrations in lean flames from increasing much above the initial values at the combustion zone; these same cooling rates do not prevent oxidation of most of the initial carbon monoxide.

Jan 1, 1967

By H. Reginald Hardy

This report is Volume II of a three volume final report dealing with the microseismic monitoring of a longwall coal mine. The research presented in Volume II is concerned with the evaluation of field techniques for obtaining seismic velocity data required for computing microseismic source locations. The report describes the evaluation of a number of different field techniques and the seismic velocity data obtained at the Greenwich mine site where the micro-seismic studies, described in Volume I of the final report, were carried out. Three different methods were employed to evaluate seismic velocities, namely; surface refraction, down-hole, and transmission. In all cases the seismic sources were either located on surface (mechanical impact) or near-surface (explosive charges). It was found that a mechanical energy source could be conveniently utilized to determine shallow velocities and make bedrock-regolith interface depth determinations. For deeper velocity determinations suitable explosive charge sources Here required. In general, refraction data did not always plot in a linear manner and some subjective interpretation was necessary. The down-hole method was found to be useful for incremental vertical velocity evaluation, however, the transmission method provided the most consistent average vertical velocity data. At the Greenwich site seismic velocities were found to be anisotropic with values ranging from 9,551 to 10,739 feet per second depending on direction.

Jan 1, 1977

By W. W. Agey

This report summarizes results of bench-scale metallurgical studies by the Federal Bureau of Mines on three composite samples representative of the low-grade manganese ores purchased by the General Services Administration (GSA) and stockpiled at Deming, N. Mex., and Wenden, Ariz. Bench-scale flotation tests at the Salt Lake City Metallurgy Research Center showed that all three composites could be beneficiated by flotation to recover 88 to 90 percent of the manganese in concentrates that assayed from 38.5 to 39.0 percent Mn, 10 to 12 percent insoluble, 5 percent CaO, 3 to 5 percent Fe, and 1.3 to 1.7 percent combined Pb plus Zn plus Cu, Sintering studies indicated that specification-grade material could be made from these concentrates by sintering above 1,000° C, and adding either sodium or calcium chloride to the charge to insure removal of enough lead and zinc to meet the specifications.

Jan 1, 1962

By G. W. Jones

In cooperation with the Edison Electric Illuminating Co. of Boston, Mass., and the Boston Consolidated Gas Co., a survey has been conducted continuously since 1929 by the Bureau of Mines to determine the general hazards of combustible gases and vapors in manholes of the Edison Electric Illuminating Co. The New England Telephone & Telegraph Co. also has cooperated in the investigation, and tests have been made in its manholes since May 1, 1933. Yearly reports6/ on the results obtained since the beginning of the survey have been published. The method and procedure of conducting the survey in 1936 were the same as heretofore.

Jan 1, 1938

By S. C. Termes

The Bureau of Mines conducted research on the flocculation of various minerals with insoluble cross-linked starch xanthate (ISX) to determine its potential as a beneficiation technique for low-grade, highly dissem-inated ores and for selective desliming. Covellite, chalcocite, pyrite, pyrrhotite, chalcopyrite, bornite, sphalerite, galena, and molybdenite fines flocculate with ISX. Floc formation, floc size, and settling rate are dependent on pH, with the pH dependence differing for each mineral. Quartz is not flocculated by ISX. Experiments to obtain selective flocculation of sulfides from quartz were attempted. Good selectivity was only obtained for the bornite-quartz system. postflocculation separations resulted in flocculated bornite in grades as high as 92 pet. Evidence is presented that the flocculation of many of the sulfide minerals with ISX may involve covalent bonding of the xanthate group to lattice metal site(s).

Jan 1, 1983

By G. W. Jones

In cooperation with the Edison Electric Illuminating Co. of Boston, Mass., and the Boston Consolidated Gas Co., a survey has been conducted continuously since 1929 by the Bureau of Mines to determine the general hazards of combustible gases and vapors in manholes of the Edison Electric Illuminating Co. The New England Telephone & Telegraph Co. also has cooperated in the investigation, and tests have been made in its manholes since May 1, 1933. Yearly reports6/ on the results obtained since the beginning of the survey have been published. The method and procedure of conducting the survey in 1936 were the same as heretofore.

Jan 1, 1938

By Nadia C. Miller

In situ stope leaching is an innovative mining system that reduces the surface impacts of conventional underground mining. As in any leaching operation, stope leaching requires hydrologic site characterization and control of leaching solutions. Several tracer tests, using sodium chloride (NaCl) in various concentrations, were conducted by the U.S. Bureau of Mines (USBM) in an underground experimental stope to simulate a leaching environment. The tests were conducted in fractured crystalline rock that was partially water-saturated. As tests progressed, the surrounding fractures became more saturated. A predominant flow direction away from the stope was found during testing. Testing procedures, results, and a remediation plan for in situ leaching based on field observations are presented in this report.

Jan 1, 2010

By William H. King

Preliminary examination of the Virgin River manganese deposit was made by C. H. Johnson, Bureau of Mines engineer, in March 1941. During, April and May 8 trenches were dug, a 48-foot inclined shaft was sunk, and 719 linear feet of channel samples were cut. McKelvey and Wiese, of the Federal Geological Survey, completed mapping the deposit, including the entire area of overlying formations comprising the point of land between the outcrop and Lake Mead. The geologic maps, maps, and ore estimates resulting from these examinations formed the basis for a preliminary report by C. H. Johnson, who recommended further exploration by diamond drilling.

Jan 1, 1949

By John L. Morning

Although faced with a slowdown in the world economy, continued inflation, and rising costs, the mining industry exceeded its 1974 raw mineral production value of $55.1 billion by 13%. The increase was due to value increases in the production of fuels and nonmetals; metals reported a decrease in value. Of 23 metals produced, 14 showed value increases; of 44 non-metals produced, 26 reported value in-creases. Because of increasing costs and depletion of high-grade reserves, the mining industry continued to rely on new technologies to maintain its profit margins. In the surface mining sector, the development of new tools and equipment played a large part in increasing production and maintaining this goal. Some of the types of equipment developed were instrumentation for control of pit slope stability, shovel power transmissions, electric wheel trucks, and single-flight conveyor systems.

Jan 1, 1977

By David E. Siskind

The Bureau of Mines recorded particle accelerations in the mine roof produced by three types of explosives in the Pilot Knob Pellet Co. mine, Pilot Knob, Mo. Examined were the effectiveness of cube root, square root, and two-thirds power scaling in grouping the underground blast vibration data, and the effects of mine geometry, rock type, explosive type, and charge size on blast vibration levels. A propagation law for this mine was determined. The scaling factor of the square root of the charge weight was developed from previous Bureau studies of vibrations from quarry blasts, and in under-ground blasting both square root and cube root scaling were found applicable for scaling particle vibration data. The vibrations from the Pilot Knob blasts were best grouped by a square-root scaling factor. The empirical propagation equation AW1/2 = 76,250 (R/W1/2)-2.61 where A is the peak acceleration in g's, W is the charge weight in pounds, and R is the distance from the blast in feet, may be used to describe vibration amplitudes from charges fired with zero delay caps or with a single cap at Pilot Knob. Statistically significant differences were found in the vibration levels generated by the different explosives. The Power Primer (75-percent weight-strength ammonia gelatin dynamite) produced levels of vibration of 1.7 to 2.4 times those of AN-FO and slurry explosives; the latter two are approximately equal.

Jan 1, 1973

By Verne E. Hooker

In situ stresses, based on isotropic and anisotropic relations, were evaluated using computer techniques from overcoring data obtained in dimension stone quarries along the Appalachian Piedmont, the Ozark Uplift, and the Ouachita Tectonic Belt. Stresses in the horizontal plane near the surface are compressive and range from 100 to 4,500 psi. The direction of maximum compressive stress seems to be alined with the general tectonic structure for most of the determinations. The ratio of the maximum to minimum elastic parameters in the horizontal plane ranges from 1.05 to 2.46 for these competent rocks. Isotropic versus anisotropic stress determinations show differences only as great as 25 percent in stress magnitude and 25° in orientation.

Jan 1, 1969

By Lawrence G. Houk

Monazite sand is the only commercial source of cerium, other rare-earth metals and thorium. Although used in rather small quantities, it is essential to many industries. The United Unites is entirely dependent upon British India and Brazil for its supplies. Monazite sand or sand imported under the tariff classification for monazite was shipped to the United States in greater quantities, in 1940 than ever before. About 75 percent of our imports was from British India and most of the remainder from Brazil. If need be, Brazilian production can be expanded to supply all of our essential requirements, and the theater of war expands in the Pacific Brazil may supersede India as the principal source. PHYSICAL PROPERTIES The mineral monazite is generally honey yellow or may vary from greenish yellow to clove brown. The grains are small and resinous in luster, and range from subtranslucent to opaque. The specific gravity varies

Jan 1, 1943

By Charles D. Litton

This U.S. Bureau of Mines report details the results of a series of large-scale experiments where small coal fires were used to ignite the conveyor belt at air velocities ranging from 0.76 to 6.1 m/s. In the tests, electrical strip heaters imbedded within a pile of coal were used to heat the coal to a point of flaming ignition. The flaming coal subsequently ignited the conveyor belt located approximately 5 to 10 cm above the coal pile. During the tests, temperature, CO, and smoke levels were continuously measured in order to determine both alarm time and level as the fire intensity progressed through the stages of smoldering coal, flaming coal, and flaming coal plus flaming belt. Analysis of the data leads to certain conditions of air velocity and sensor alarm levels that are required for early detection of conveyor belt entry fires. Two nomographs are presented, which define sensor alarm levels and sensor spacings as a function of belt entry cross-sectional area and belt entry air velocity.

Jan 1, 2010

By Edward W. Parsons

Conventional rock-bolt anchors often fail when installed in weak formations. The purpose of this work was to develop an anchor that would utilize an explosive charge to secure anchorage in any type of rock. Laboratory work to develop a rock-bolt anchored by explosive forming was initiated using rock-bolt models which had a drilled explosive chamber and were composed of various metals. This was followed by the use of several types of seamless tubing which were expanded with a water-coupled explosive capsule. By attaching a length of solid bolt to the anchor tube, a prototype explosive-anchored rock bolt was made. More than 150 laboratory models were expanded during this phase of development, During two field tests in underground mines (A and B) and one in an open- cut mine (C), 87 explosive-anchored bolts, 9 slot-and-wedge bolts, 2 bolts anchored with expanding grout, and 28 expansion-shell bolts consisting of three types of shells were installed and subjected to pull tests. The field tests were run to determine the effects of variables such as the amount and placement of the explosive charge, design changes in the bolt, and the effect on anchorage of different pull-test techniques. The field tests revealed the following: Mine A. The explosive-anchored rock bolt was feasible, but changes were necessary in bolt materials and in some details of bolt design. Mine B. The design and materials of the bolt gave excellent results in hard fractured rock, but no information was obtained concerning variations in the dimensions of the anchor unit or in the explosive charge. Nine C. Varying the explosive charge to produce a beaded surface on the bolt tube and tightening of the anchored bolt before pull-testing were found to increase significantly the anchorage obtained in soft ground.

Jan 1, 1963

By S. L. May

Investigations by the Federal Bureau of Mines indicate that hafnium and zirconium compounds of acceptable purity can be extracted from Nigerian zircon concentrates. Chlorination and caustic soda fusion techniques were used to extract 85 to 95 percent of the valuable metals from the concentrate. The extracted hafnium and zirconium compounds were purified by recrystallization of the oxychlorides or by formation of complex salts during chlorination. The zirconium-hafnium product of the recrystallization method contained 15 parts per million of uranium, and the product of the salt-complex method contained less than 10 parts per million of uranium. The hafnium was separated from zirconium by solvent extraction methods. A zirconium product containing 0.3 percent hafnium and a hafnium product containing 4 percent zirconium were obtained. At the request of the Atomic Energy Commission (AEC), work was started to develop techniques for processing Nigerian zircon concentrates in commercial installations presently engaged in producing zirconium and hafnium metals from ores. The Nigerian zircon has a high hafnium content, but the presence of uranium and thorium is a problem not normally encountered in processing zircon concentrates.

Jan 1, 1961

By Richard D. Miller

This Bureau of Mines publication contains analyses and related source data for 271 natural gas samples from 22 States collected during calendar year 1982. All samples were obtained and analyzed as part of Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by the mass spectrometer and chromatograph. The results of the investigation of the occurrences of helium are published annually to make the information available to the petroleum industry and the general public. Twenty-six publications have presented the results of 13,051 gas analyses vide prior to 1982. The first 3 bulletins (1-3)3 contain analyses and related source data on 5,218 gas samples collected from 1917 through 1960; these bulletins have been supplemented annually by information circulars (4-17, 19-24, 26) containing 7,833 analyses of samples collected since 1960.

Jan 1, 1983

By Robert E. Barieau

This report describes a method for treating pressure-volume-temperature (PVT) data obtained with a Burnett compressibility apparatus. The method makes use of a general nonlinear least-squares technique developed at the Bureau of Mines Helium Research Center. It is assumed that an adequate functional form is available for the expression of the compressibility factor as a function of either the molal density or the pressure. The functional form of the compressibility factor can be either linear or nonlinear in the parameters to be evaluated. Formulas are given for calculating variances and covariances of all parameters evaluated and for calculating the variance of calculated quantities of interest.

Jan 1, 1967

By Erich K. Bender

This report summarizes work performed under Phase I of USBM Contract No. H0366024, Noise Reduction of Jumbo Mounted Percussive Drills. Four drills -Gardner-Denver D93LAR and DH123 and Ingersoll-Rand 0475 and VL120 models were measured at the two manufacturers? test sites; data are given in terms of characteristic noise and vibration levels. A survey of percussive rock drill users is reported. The rationale for the choice of a demonstration drill, the Gardner-Denver DH123, is given and a desired noise reduction goal is established.

Jan 1, 1976

By Richard O. Kneisley

An empirical method, based on U. S. Bureau of Mines field studies in several Western U.S. coal mines, is presented for sizing gate road yield pillars. Discriminant analysis was used to generate functions separating successful from unsuccessful case studies. These functions relate the pillar width-height and extraction ratios and a pillar development factor to the Coal Mine Roof Rating System (CMRR), and are assumed to establish three criteria that other entry systems, under similar conditions, must satisfy. A program, Pillar Sizer, from user-provided inputs, generates a range of pillar sizes that meets the proposed criteria. Although the analysis is based on a sample consisting primarily of two-entry systems, the derived expressions generate pillar sizes closely agreeing with observed, two-entry and three-entry in situ pillars. It is concluded that the proposed approach should assist mine operators estimate entry system yield pillar dimensions.

Jan 1, 2010

By E. B. Olds

This paper describes the methods and costs of deepening the 3-compartment underground shaft in the Hooper Tunnel adit at the Bunker Hill & Sullivan Mining and Concentrating Company Crescent mine in the Coeur d'Alene mining region, 7 miles east of Kellogg, Shoshone County, Idaho. The work was done with the aid of a Defense Minerals Exploration Administration contract (No. Idm-E493, Docket No. DMEA-2764). Preparation for deepening the shaft was begun March 26, 1953, and sinking was completed May 27, 1954. The shaft, bottomed at 1,275.5 feet in 1939, was deepened to 3,276 feet, using mechanical mucking and intermediate pockets. A total of 50,349 man-hours was required to complete the work of sinking 2,000.5 feet, cutting 7 pump stations, and driving 2 pocket raises. The rate of advance was 7.1 feet of shaft per operating day, or 8.4 feet per day of actual sinking. The total direct cost for sinking was $205.20 per foot.

Jan 1, 1957