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By Ralph B. Youtz

This paper describing mining methods at, the Eighty-Five mine of the Calumet and Arizona Mining Co., Valedon, N. Mex., is one of a series being prepared by the United States Bureau of Mines on mining methods, practices, and costs in the various mining districts in the United States. The Eighty-Five mine is in southwestern New Mexico, 3 miles southwest of Lordsburg, Hidalgo County (see fig. 1). The mine produces normally 7,000 to 8,000 tons per. month of silicious copper-gold-silver ore, and employs approximately 200 men underground and 40 on-the surface. Mining is done by shrinkage and cut-and-fill methods.

Jan 1, 1931

By Sumner M. Anderson

THE ENORMOUS contrast between the mineral economy of Cuba in 1963 and in 1958 was the result of the overall Political changed to which the total economy of the country was intimately lined. Creation of the Cuban Mining Institute (Instituto Cubano de la Minería) to direct all mining activities in the country was an early act of the new Government after the revolution on January 1, 1959. During the next 2 years, the Government confiscated foreign holdings,2 including Unite States investments exceeding $1 billion in value. Foreign mining and metallurgical technicians-predominately from Communist areas-were brought in to reorganize the mineral industries. On January 3, 1961, diplomatic relations between Cuba and the United States were severe and then on May 2, Cuba announced its full-fledged membership in the so-called Communist Bloc. Fifty-four international treaties assured Cuba of Communist economic support, technical and financial assistance, machinery, raw materials, and manufactures. The Soviet Union agreed to buy some Cuban mineral products, and Czechoslovakia stated that it would buy all mineral production offered for the next 20 years, but in both cases at prices said to be much lower than the world market. The mineral productivity segment of the mineral economy during and since the period of political metamorphosis, has withstood the political disruption better than has the economy as a whole, but with no direct measure of the magnitude of its cost. The overall economic record is marked with steady deterioration; the annual average per capita income has dropped from $374 in 1957 to $185 in 1963, when Cuba's deficit with the Soviet Union alone reached an admitted $1 billion.

Jan 1, 1964

By J. W. Town

As part of the Federal Bureau of Mines titanium resources examination program, samples from seven deposits in the Pacific Northwest were tested for amenability to various beneficiation techniques. The samples obtained by the Bureau's Office of Mineral Resources at Spokane, Washington represent a large potential source of titanium. This report summarizes the results of tests at the Bureau's Metallurgy Research Center, Albany, Oregon. Recoveries from tabling placer samples were about 50 percent at grades of 30 percent titanium dioxide. Flotation was the most effective method for concentrating the fine ilmenite in clay samples; recoveries of approximately 50 30 percent titanium dioxide. Flotation was the most effective method for concentrating the fine ilmenite in clay samples; recoveries of approximately 50

Jan 1, 1961

By M. M. Tilman

The Bureau of Mines conducted research to determine whether it is possible to substantially improve the fatigue resistance of lead sheet by means of surface coatings. Five types of coatings were applied to unalloyed chemical lead sheet. Flexural tests revealed that the best fatigue resistance was obtained with coatings of vacuum grease. Vacuum-grease coatings on unalloyed lead sheet resulted in fatigue resistance at least as good as that of the fatigue-resistant alloy Pb-0.04 Ca. Coated lead sheet was also tested in short-time tensile tests and in tensile creep tests. Tensile and yield strengths were increased by several of the coatings with only moderate loss of ductility. Creep resistance was also improved in varying degrees by most of the coatings. The Bureau also conducted research on the effectiveness of noise barriers by using sheet lead in combination with other materials. Noise barriers consisting of continuous-cast sheet lead with gypsum board were found to be effective and relatively inexpensive barriers.

Jan 1, 1978

By Edward Thimons, William A. Hertbrink

The effect of wind speed upon aerosol penetration into an idealized enclosure was studied The idealized enclosure was a painted plywood box that was 1 2X1 2 XI meters in volume Two fans supplied 1 7 m3 /min of filtered air to this enclosure at a static pressure of 2 8 mm of water The enclosure had a 7 5 cm diameter vent port which was isolated from the air flow around the enclosure To simulate holes in real enclosures, three 16-cm diameter holes were drilled on the front and back sides of the enclosure This simulated enclosure was placed in a tunnel-like structure The air flow from an ultra-light air craft was directed at the front of the enclosure The air speeds were varied between 14 and 36 km/hr as measured by rotating vane anemometer Static pressure in the enclosure was measured with an electronic manometer Two optical particle counters measured the particle number concentration of particles between the 0 35 to 0 5 µm inside and outside of the enclosure Aerosol penetration into the enclosure was computed as the ratio of the aerosol concentration inside the enclosure to the concentration outside of the enclosure The enclosure static pressures measured increase from 2 8 to 3 4 mm of water (P=00001) Aerosol penetration into the enclosure increased linearly with air velocity above 20 km/hr Theoretically estimated penetrations were correlated with observed penetration into the simulated enclosure When simple linear regression was used to model the observed penetration as a function of the estimated penetration, the value of the slope was 0 69±0 12 and the P value for the regression model was less than 0 0001 These results indicate that enclosure static pressure needs to be higher than the wind's velocity pressure in order to minimize aerosol penetration into these enclosures

Jan 1, 1999

By James L. Konchesky

Crushed coal, consisting of a wide range of sizes, was effectively blended by recycling it through a bin equipped with a particle distributor. Vertical blending was accomplished by simply recycling the coal; it was not significantly influenced by the horizontal blending that was achieved by the distributor. The method was effective, even though the coal was wet and possessed poor flowing characteristics. Recirculation appears capable of providing uniform blends of solids that can be more efficiently processed. Recirculation also appears useful, preceding packaging operations, to insure for blending of solids into specification products. Continuous measurement of the bulk density of the coal by a gamma ray meter proved to be an effective monitor of vertical blending effectiveness.

Jan 1, 1972

By John C. Edwards, Gene F. Friel, John J. Opferman, Robert A. Franks

As the use of deep -rut mining increases, there - expected to be a greater demand for methane (CH,) measurement devices capable of scanning working faces al depths in excess of 10 m to alert mine personnel of hazardous concentrations of CH and to satisfy regulatory requirements. Remote optical devices offer the most promise to satisfy these objectives while the operator remains safely under supported roof. A second¬-generation remote Optical methanomeor (ROM) bas been designed and Is undergoing laboratory evaluation at the National Institute for Occupational Safety and Health. It operates on the principle of differential absorption of the "u;' fundamental absorption band of CH, centered at 3.31 um in the infrared region of the spectrum. The new instrument differs from the previous prototypes by the replacement of the two hand pass differential absorption technique of measurement with a single filter gas correlation technique and a refinement of the amplifier and gating circuitry used within the unit. This results in a more accurate isolation of the CH, spectral absorption band centered at 3.31 um. A specially designed 0.4m-diam variable-length gas mixing tunnel was constructed and instrumented with CH4 sampling capability to calibrate the ROM. Experiments have demonstrated the ability of the detector to respond to various conditions of CH, (pn•m) at distances as great as 12 m. Thermal radiation generated within the instrument is the controlling factor in the drift of the output signal nod, therefore the reliability of the instrument. Several approaches to reduce this extraneous radiation interfering moth the infrared detector, described, such as the installation of a fan in the instrument and thermoelectric coolers on the detector's beat sink. Implementation of this technology will significantly improve the safely of miners.

Jan 5, 1997

By Otto Robert Stein

Erodibility of reclaimed surface mine soils is a subject in need of quantification. Effects of soil erosion from reclaimed areas may damage surrounding areas and the quality of water in nearby streams and lakes. It may also reduce the potential productivity of the reclaimed site. A study was conducted to determine erodibilities of different reclamation treatments and a nearby unmined soil at three Indiana strip mine sites. A rainfall simulator was used to artifically erode plots con¬structed within seven treatment categories and the unmined soil. Soil erodibility was assessed in terms of the Universal Soil Loss Equation (USLE) K factor. Values for K calculated from field data were compared to values predicted from independently measured soil properties. Differences in soil erodibility between treatments were site specific. Unmined soil had the highest calculated erodibility at one site but at two other sites soils having reclaimed A horizons were highest. Shaley overburden treatments had the lowest calculated erodi¬bility. Predicted soil erodibility was usually lower than that calcu¬lated from field data. Site specific slope gradient factors (S) were developed for reclaimed A horizon treabnents. This was done because the USLE S factor overestimated the measured soil loss at steeper slopes.

Jan 1, 1983

By R. E. Perry

To develop new or improved flotation methods for beneficiating low-grade red iron ores, the Bureau made many bench scale and continuous anionic flotation tests on ferruginous sandstones and calcareous iron ores from the north-eastern part of the Birmingham, Ala., iron district. The ores contained about 21 to 36 percent iron, a to 11 percent lime, and 22 to 64 percent silica. Production of iron concentrates containing 48 to 52 percent iron was technically feasible in batch tests, and the iron recoveries ranged from 85 to 92 percent. In continuous tests 49 to 51 percent iron products were obtained with 80 to 90 percent recovery.

Jan 1, 1962

By Wilbert J. Huff

The organization of the Explosives Division is indicated by the accompanying chart (fig. 1). As this has been discussed in a previous report3/, it will not be considered further in this report. The activities of the various units are outlined below. I. INFLAMMABILITY OF GASES AND VAPORS4/ Determination of the Explosion Hazards of Combustible Gases and Vapors Found in Mines and Industries The Explosives Division maintains, at the Pittsburgh Experiment Station, a laboratory specially equipped for the determination of the explosion hazards of combustible gases and vapors. Of particular importance, is the determination of the chemical composition within which explosions may occur and beyond which there is no danger of explosion, combustion or inflammation. These limits, known as the limits of inflammability, as determined by this and other laboratories, have been compiled in Bulletin 279 of this Bureau. The last revised edition (1931) of this bulletin has been exhausted. Since it was published, the Pittsburgh laboratory has determined the limits of about 40 combustibles and has ascertained more precisely ant accurately many previously published limits.

Jan 1, 1938

By Wilbert J. Huff

The organization of the'Explosives Division is indicated by the accompanying chart (fig. 1). As this has been discussed in a previous report3/, it will not be considered further in this report. The activities of the various units are outlined below. I. INFLAMMABILITY OF GASES AND VAPORS4/ Determination of the Explosion Hazards of Combustible Gases and Vapors Found in Mines and Industries The Explosives Division maintains, at the Pittsburgh Experiment Station, a laboratory specially equipped for the determination of the explosion hazards of combustible gases and vapors. Of particular importance, is the determination of the chemical composition within which explosions may occur and beyond which there is no danger of explosion, combustion or inflammation. These limits, known as the limits of inflammability, as determined by this and other laboratories, have been compiled in Bulletin 279 of this Bureau. The last revised edition (1931) of this bulletin has been exhausted. Since it was published, the Pittsburgh laboratory has determined the limits of about 40 combustibles and has ascertained more precisely and accurately many previously published limits.

Jan 1, 1938

By J. W. Jensen

Alloys of manganese and copper containing from 65 to 80 percent manganese possess mechanical strength and vibration-damping capacity in an unusually high degree. The success of their use in reducing vibration in structures depends, to some extent, on their fatigue properties. This report describes the results of fatigue tests on alloys of four compositions. Three metallurgical conditions were investigated for each alloy. Or the basis of the data in this report, the general rule that vibration-damping manganese-copper alloys are comparable to mild steel in hardness and strength may be extended to include fatigue strength. Methods for casting and fabricating these alloys were described in a previous report,4 which contained data on the mechanical and damping properties of the solid-solution alloys, and on alloys aged for 2 hours at 450° C. The aging heat treatment of solution-treated alloys results in optimum mechanical and damping properties throughout the range of specified composition. However, in the present work, measurements also were made on alloys aged for 2 hours at 500° C., because it was theorized that the additional precipitation of a-manganese under these conditions might have a pronounced effect on the fatigue strength of the alloy.

Jan 1, 1961

By V. E. Homme

This report describes methods of using sodium for reducing titanic chloride, developed as part of Bureau of Mines activities at Boulder City, Nev., to improve the extractive metallurgy of titanium. Theoretical indications pertaining to the major chemical reactions and possible side reactions of the process are compared with experimental observations. Low-temperature reduction equipment is described, in which titanic chloride was reduced with sodium at temperatures between 97.5° C., the melting point of sodium, and 200° C. Techniques employed in making reductions in ball-mill and high-surface sodium reactors are given.

Jan 1, 1958

By Christopher C. Jobes, Alan G. Mayton, Farid Amirouche

Based on prior mine vehicle studies of operators’ exposure to whole-body vibration, researchers from the National Institute for Occupational Safety and Health (NIOSH) evaluated four seat designs on mine haulage vehicles, with regard to roadway-induced jarring/jolting and operator comfort. Investigators collected objective and subjective data from vehicle operators on two existing and two NIOSH seat designs. This study included time and frequency response data using accelerometers and a data recorder, operator perceptions of jarring/jolting and discomfort levels using a linear visual analogue scale, and data from a questionnaire developed for this study. Results from the analysis of subjective data show that operators generally favoured the NIOSH-designed seats over the existing seats. The results of analyses from the absorbed power method and the threshold limit method, based on ISO 2631-1 (ISO, 1985), support the premise that NIOSH seat designs are superior to the existing vehicle seat designs on both models of mine shuttle cars used in the study. The NIOSH seat designs, featuring viscoelastic foam padding, were more effective in reducing vibration energy for operators exposed to vehicle jarring/jolting. In this paper, the performances of the NIOSH and existing seat designs are compared relative to the operator’s exposure to vehicle vibration (mainly jarring/jolting).

By Paul R. Thimas, Edward H. Boyle

"The Bureau of Mines evaluated the long-term cost and availability of primary gold production from 135 mines and deposits worldwide. Collectively, the evaluated countries represent 93 pct of world gold production. Total recoverable gold available (as of January 1984) from a subset of 111 significant producing mines and developing deposits in 13 market economy countries (MEC's) is estimated at 810 million tr oz. The Republic of South Africa is estimated to account for 87 pct of total recoverable gold. The United States and Canada account for 4 and 4.5 pct of the total, respectively. Eighty-three percent of total recoverable gold is available at a constant 1984 break-even price of $400/tr oz, and 70 pct is available at $300/tr oz. South Africa accounts for 90 pct of the gold available at $400/tr oz or less.Major conclusions are that (1) South Africa should remain the largest world producer through the year 2000, (2) annual MEC output in 2000 should not be significantly different than current output given constant 1984 gold prices of more than $300/tr oz, and (3) there may be a significant decline in production after 2010 in the absence of major new discoveries and continued development of new mines to offset the depletion of the South African mines. INTRODUCTIONSince the late 1970's the world gold mining industry has been characterized by dynamic growth in production and volatility in price. World production in 1983 was almost 15 pct greater than in 1980, and the short-term trend continues upward. Annual dollar-based price changes since the early 1970's have been unprecedented in both magnitude and volatility. This commodity, which sold for $35/tr oz3 for over a third of a century, reached an annual average $612/tr oz in 1980. Until 1980, the future price of gold seemed set on an upward trend. Since that year, however, world gold prices have fallen by over 50 pct to slightly over $300/tr oz at the end of 1984.Against this background, this study was undertaken to determine (1) the level of world demonstrated gold resources, (2) total and annual availability of gold mine production, (3) long-run production costs per operation and by national aggregates, (4) the economic and technical factors that impact upon cost and availability, and (5) probable future mine production and cost trends."

Jan 1, 1985

According to contemporary psychophysical theory, the relationship between the strength of a perceived sensation (S) and the intensity of a physical stimulus (1) is best expressed by a power relationship.(1) S=kln (1) This psychophysical principle has been applied to many practical problems, including the development of scales or guidelines for effective temperature, loudness, brightness, and ratings of perceived exertion. Based on the results of a number of experiments using a variety of scaling methods and a number of different muscle groups, the pooled estimate of the exponent for muscular effort and force is 1.7.(2) When applying this principle to work situations, it is assumed that individuals are capable and willing to consistently identify a specified level of perceived sensation (S). For manual materials handling tasks, this specified level is usually the maximum acceptable weight or maximum acceptable force. These phrases are defined by the instructions given to the test subject:(3) You are to work on an incentive basis, working as hard as you can without straining yourself or becoming unusually tired, weakened, overheated, or out of breath. If the task involves lifting, the experiment measures the maximum acceptable weight of lift. Similarly, there are maximum acceptable weights for lowering and carrying. Such tests are isoinertial in nature; however, in contrast to the tests described in Chapter 3, they are typically used to test submaximal, repetitive handling capabilities. Data are also available for pushing and pulling. These are reported as maximum acceptable forces and include data for initial as well as sustained pulling or pushing. Why Use Psychophysical Methods? Snook identified several advantages and disadvantages to using psychophysical methods for determining maximum acceptable weights.(4) The advantages include: • Realistic simulation of industrial work (face validity); • Ability to study intermittent tasks (physiological steady state not required); • Results are consistent with the industrial engineering concept of "a fair day's work for a fair day's pay"; • Results are reproducible; and • Results appear to be related to low-back pain (content validity).

Jan 1, 1998

By Larry D. Nichols

Poroplastic membranes containing ion exchange liquids were studied for separating cobalt from nickel-containing solutions similar to ammoniacal laterite leaches. The driving force for cobalt transport was differences in pH and composition between the leach and extraction streams. Using a diketone ion exchange liquid, a leach pH of 6.5 to 7.0, and a strip pH of 2.3, cobalt was extracted from a 750 ppm solution containing 2500 ppm of nickel at rates ranging from 1 to 10 µg/cm2 .min in single membrane cells, and from 10 to 100 in more closely spaced multiple membrane cells. Rates were variable, with evidence that cross -membrane flow pasterns were a key factor; a reproducible rate of 30 pg/cm .min would be economically viable. Loss of transport observed after several days of continuous operation was restored by flushing membranes with fresh ion exchange liquid. A major effort was devoted to preparation of thin, leak-free membranes; the resulting membranes endured operating conditions without mechanical failure.

Jan 1, 1982

By H. L. Burmeister

These properties were examined by a Bureau of Mines engineer in 1949. During 1950, these mines were studied by the Bureau to determine the possibility of increasing the production and augmenting the supply of fluorspar. As a result of this study, it was decided to core-drill the Knox-Yingling vein to test the continuation of fluorspar to a greater depth than that reached by mine workings. It also was desired to relate the present deposit with the Rosiclare formation. Development work by the Bureau of Mines was performed from February to May inclusive in 1951. Four diamond-drill holes aggregating 2,733 feet were drilled in the hanging wall of the vein.

Jan 1, 1952

By H. E. Camargo

In an effort to decrease noise-induced hearing loss (NIHL) in coal preparation plant employees, the National Institute for Occupational Safety and Health (NIOSH) is conduct­ing research to identify and control dominant noise sources in vibrating screen (VS) machines. To this end, acoustic measurements of the noise radiated by a dewatering VS were conducted at the Pittsburgh Research Laboratory (PRL) using microphone phased-array technology. These measurements allowed for the identification of the screen as the dominant source in the 250 Hz 1/3-octave band. The sidewalls are the major contributors in the 315 and 400 Hz bands, whereas the eccentric mechanisms and the electric motor are the dominant sources in the 800 and 1,000 Hz bands, respectively.

Jan 1, 2009

By Paul M. Tyler

Calcium chloride is a conspicuous example of a former waste product that has found a place for itself in the onward march of civilization. Formerly considered a troublesome constituent of the effluent sewage of many chemical manufacturing plants and salt works, it has now become a commercial product of substantial importance, with sales aggregating almost six million dollars in 1929. The point has not yet been reached where it would seem profitable to undertake large-scale production of calcium chloride as a main product, but as a byproduct it has become an item that warrants serious consideration by all who are in a position to recover it at sufficiently low cost. The largely increased demand for bromine and for certain magnesium salts, which are likewise potential byproducts associated with calcium chloride in most salt-works bitterns (and brines generally), adds further impetus to commercial research directed toward the fuller utilization of the natural saline resources of the United States.

Jan 1, 1934