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By P. C. Tully

The vapor pressure-temperature relationships for saturated pure liquid nitrogen are calculated by the Strobridge equation using a digital computer. This information is presented in two tables: first) in pressure increments of 0.1 psi from 1.8 to 492.9 psia) and second) in temperature increments of 0.1° from 63.15° to 126.26° K. These tables should facilitate the calibration of temperature-measuring devices over this temperature range.

Jan 1, 1967

By Theodore R. Jolley

The estimated recoverable reserves in the area in the vicinity of Eska 2 mine are, 699,300 tons in the Chapin and Emery bas of the Maitland group. Those recoverable reserves are in the area between the Eska fault zone and Jonesville fault and extend down dip from the outcrops. No reserves were developed by the Eska 2 entry or by drill hole 14-16 in the Eska fault zone. The small quantity of reserves in the vicinity of the Eska 2 mine is insufficient to justify development of a now, modern .nine in this area. The estimated recoverable reserves in the area east of aka Creek are 974,500 tons in the Eska, Shaw, and Martin beds of the Eska group. Most of those reserves occur in the south limb of the syncline. It will be necessary to practice subjacent mining methods to recover these reserves in the Eska group. The Eska bed developed by the diamond drilling in this area comprises coal end few thin partings. The Shaw and Martin beds comprise two bunches of coal separated by partings, and the product from full-bed mining will require thorough preparation.

Jan 1, 1952

By John J. Henn

As part of the U.S. Department of the Interior programs on rutile, authorized by the Office of Emergency Preparedness in June 1967 under provisions of the Defense Production Act, the Bureau of Mines reviewed available literature on major proposed processes for producing rutile substitutes. The processes are grouped according to the major processing step, and important operating features are described. Sixty-one references are cited.

Jan 1, 1970

By Roy L. Wilfong

The thermal decomposition of the ammonium sulfate, carbonate, nitrate, oxalate, and sulfate salts of praseodymium, neodymium, and samarium was investigated thermogravimetrically in the temperature range 25° to 1,500° C. Each salt was decomposed at a heating rate of 2.5° C, per minute. The pyrolytic sequences have been identified and the temperatures of formation of inter-mediates, the minimum oxide formation temperatures, and values for loss on ignition have been determined. The nonstoichiometric ranges between Pr6011 and Pr203 and the extent of these ranges have been determined for oxides derived from the carbonate, nitrate, and oxalate salts of praseodymium. The alum and sulfate salts of praseodymium produced the sesquioxide without forming the intermediate non-stoichiometric oxides. The temperature limits of formation and regions of stability for the alums and sulfates were better defined than were those for the carbonates, nitrates, and oxalates. The minimum oxide formation temperature increased in the order of samarium, neodymium, and praseodymium irrespective of the anion.

Jan 1, 1962

By Tom Tallone

In the majority of metal and nonmetal mining operations, narrow vein deposits are being mined with slusher hoists. Thin; method of mucking is costly, due in part to its inherent labor intense operation and to its inability to muck 100 pct of the deposits. Mechanized equipment would greatly improve the material handling in narrow vein mining and would dramatically reduce the operational cost. The Compact Loader/Trammer, known as the "mini-mucker" has been developed to increase productivity of the load/haul/dump portion of the typical narrow vein mining cycle. This is Volume II of the final report and concerns the operation and maintenance of the mini-mucker. Volume I covers a general and design review of the activities on the subject contract and are available under separate cover.

Jan 1, 1985

By W. W. Adams

Two important facts stand out as features of the metal- and nonmetal-mining4 industry of the United States in 1941 as compared with 1940: First, the number of employees and man-days of employment increased; second, accident-frequency rates, both fatal and nonfatal, decreased. Reports from mining companies to the Bureau of Mines covering underground, open-pit, and surface operations for 1941 re¬vealed the largest number of men employed since 1926 and the largest number of man-days worked since 1929. The combined fatal and non¬fatal accident-frequency rate for 1941, calculated on a basis of one mil¬lion man-hours of exposure to hazard, was (except for 1931 and 1932) the lowest since 1911, the earliest year for which figures are available. During this 31-year period, only 1938 and 1939 showed lower fatality rates, and only 1931 and 1932 had lower nonfatal-injury rates. Operating companies reported that 9,620 mines were active during all or some part of the year. These employed 125,290 men, an increase of more than 4 percent over 1940. The total volume of work performed at all mines, measured in terms of man-shifts, increased to nearly 32 million, a gain of 10 percent; man-hours of employment rose to almost 254 million, an increase of 10 percent over the 231 million man-hours worked in the previous year. The year's operations resulted in an average work-year of 255 days per man, an increase of 13 days per employee over the average working time in 1940. Although the 8-hour day prevails generally at most mines, the industry as a whole averaged 7.94 hours per shift, as in 1940.

Jan 1, 1944

By William N. Patterson

This report describes the design and testing of an improved quiet hard rock percussion drill. The improved drill incorporates a tappetless design with independent rotation in a hand held drill weighing 50 lbm. Laboratory and field testing in three mines were conducted. The testing showed improved drilling performance with no increase in measured noise levels over the fist design.

Jan 1, 1985

By R. Ward Stahl

The underground junction or intersection is analogous to the doorway or window in a building in that the continuous wall or support for the overhead structure has been weakened by making the opening. Some type of bridge or support seems necessary to prevent roof sag and possibly eventual failure at this point, although frequently it appears that little is done until a fatal accident induces action. The intersection generally represents less than 15 percent of the exposed roof area. As a result of recent multiple fatalities, some of which occurred at or near intersections, the Bureau of Mines was asked to examine the junction-support problem more thoroughly and to report its findings. A national survey of the junction-support systems in use has been made by correspondence, and the local area has been canvassed rather thoroughly to determine just what and how much is being done.

Jan 1, 1962

By J. L. Thompson

The U.S. Bureau of Mines conducted a water-jet-studies program using a single-bit, in-seam test unit to determine effects of a moderately high-pressure (up to 10,000 psi) water-jet-assisted cutting system on rock weakening. The in-seam test unit was used to obtain cutting force data in tangential, normal, and side force directions. Conical continuous miner and radial longwall miner bits were used to penetrate test samples of coalcrete, Berea sandstone, and Indiana limestone with unconfined compressive strengths of 4,600, 8,000 and 10,000 psi, respectively. Depth of cut in the coalcrete tests was 1 in, with 2-in cut spacing (2:1 ratio). Because of cutting equipment and instrumentation limitations, the Berea sandstone and Indiana lime-stone were cut using a 0.5-in depth of cut and 2-in spacing (4;1 ratio). Bit velocity was maintained at 25 ft/min for both bits. Each specimen and bit type was tested using 0.3-, 0.6-, 0.8-, and 1.0-mm-diam nozzles and water-jet pressures of 2,500, 5,000, 7,500, and 10,000 psig. Water-jet-assisted cutting decreased average resultant conical and radiallongwall bit cutting forces 6.4 and 8.4 pct in coalcrete, 5.5 and 1.4 pct in Berea sandstone, and 2.0 and 5.5 pct in Indiana limestone. Slight reductions of power requirements resulting from water-jet assist were ascertained during these experiments.

Jan 1, 1989

By J. M. Gomes

Bench-scale flotation tests were conducted on two western tactite ores to study the recovery of tungsten and zinc minerals. The investigation, which is part of the Bureau of Mines ongoing program to develop methods for beneficiating minerals and metals from domestic low-grade ores, demonstrated the feasibility of producing scheelite, sphalerite, and their bulk concentrates. Sphalerite concentrates containing 51 to 53 pet Zn and less than 0.11 pct W03 were selectively recovered prior to scheelite flotation. Zinc recovery ranged from 85 to 91 pct. Scheelite concentrates containing 17 to 25 pct W03 were then recovered from the ore; tungsten recoveries ranged from 88 to 94 pct. Bulk flotation concentrates containing 84 to 91 pct of the W03 and 87 to 95 pct of the zinc also were prepared. More than 98 pct of the W03 in a bulk concentrate containing 9 pct W03 was extracted by autoclave leaching with a soda solution. The zinc remained in the leached residue.

Jan 1, 1982

By G. P. Houston

This is the final, report submitted for the Contract No. H0220002 with the U. S. Bureau of Mines for the design and development of a Permissible Automatic Data Acquisition System (PADAS) to measure and record roof stresses in underground mines Basically the PADAS is a portable, battery powered, 24-channel data acquisition system designed for safe unattended operation of up to 30 days duration in explosive environments. The unit will accommodate twenty-four pressure transducers or eight borehole deformation gages (or any combination) at distances up to 300 feet from the PADAS to measure pressures up to 10, 000 psig. All 24 channels as a selected group are scanned sequentially at one of several selectable rates.

Jan 1, 1973

By G. W. Jones

In a previous report,6/ results were given that showed the amount of natural ventilation in a manhole having a capacity of 74.1 cubic feet when the number of ventilation openings in the cover was varied from no openings to a maximum of 48. The result s showed that the ventilation (air changes per day) in the manhole was proportional to the area of the openings in the cover, and also that the number or area of the openings was the factor that chiefly affected the ventilation.

Jan 1, 1937

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

1.0 Control House (DWG. NO. 56-401-G) - 1.1 Physical Description The Control House is a single story, 2728 square foot building with an adjacent transformer yard. A four foot overhang provides shade protection for the walls. The building is heated and air conditioned. The HVAC System has an elevated outside air intake and provides a positive pressure environment within the structure in order to prevent the infiltration of heavier-than-air, noxious gases. The materials of construction are as follows: Structure : Light-Gage Metal Framing Exterior Walls :Outside - Preformed, Metal Siding :Inside - Insulated Metal Liner Panels Interior Partitions :Gypsum Board over Light-Gage Metal Framing Roof :Insulated, Preformed Metal Panels Ceilings :Mechanical & Electrical Rooms - Exposed underside of Roof Panels Control Room, Lunch Room, Toilets, Entry - Suspended Acoustical Lay-In Tile Floors :Mechanical & Electrical Rooms - Concrete Slab on Grade Control Room, Lunch Room, Toilets, Entry - Resilient Tile Exterior Doorsand Windows :Preformed Metal Panel Manufacturer's Standard Units

Jan 1, 1979

By Frank D. McGuirk

Underground coal mining is traditionally hazardous. Although many danger-prone human activities are now performed by mechanized equipment, this mechanization has itself brought new dangers to the underground mining industry, and the loss of life and limb has caused increased concern for mine safety. The 1969 Federal Coal Mine Health and Safety Act has precipitated a great deal of safety-related research on the part of the Government, industry, and private agencies. Much of this safety research has been focused on the new and varied man-machine interfaces caused by increased mechanization. Recent projects in this area have dealt with standardized controls, emergency shutdown capabilities (panic bars, strike plates, self-centering controls, "dead man" controls), and machine operator protective devices (fully enclosed cabs, canopies, side rails). There was a need for integration of the findings of current and past projects to move rapidly toward the smooth, orderly implementation of standardized operator work station designs for underground mining equipment.

Jan 1, 1975

By (NIOSH) Publication

In 2004, a total of 2,011 coal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Coal mines comprised 13.9% of all mining operations.

Sep 1, 2007

By Margaret R. Lickes

Mercury was produced originally at the Idaho Almaden mine from 1939 to 1942. When the ;.nine was shut down, more than 100,000 tons of ore, containing from 2.5 to 3 pounds of mercury per ton, was known to be adjacent to old workings but had been considered too low grade for commercial operation. Later, detailed, systematic exploration by Rare Metals Corporation of America increased and delimited enough minable reserves for further operation to be foreseen for several years. The average grade of the ore is estimated at slightly more than 3.5 pounds of mercury per ton. Open-pit mining and installation of the largest rotary kiln in the United States furnacing mercury ore have made possible profitable exploitation of these reserves (fig. 1). The bulk of the exploration was by percussion drilling, although some diamond drilling was done to check the results. When enough reserves were indicated to assure a successful operation, stripping and plant construction were started simultaneously. Figure 2 is a general view of the plant. The ore bodies, although irregular in size, shape, and grade and covered by essentially barren cap rock, are amenable to low-cost, trackless, open-pit mining. Development consists of stripping the overburden and removing, barren cap rock. Ore is being mined at approximately [5],000 tons per month and treated in a 175-ton-per-day furnacing plant.

Jan 1, 1957

By T. C. Campbell

This Bureau of Mines publication presents an analysis of information related to the transportation of bituminous coal by unit trains and slurry pipelines. Even for short hauls from mines to markets, transport costs frequently account for between one-third and one-half of the delivered price of coal. Minimizing these costs has become an even more critical objective for hauls from the western mines than for hauls from farther east. Factors related to minimizing costs and transporting the western coal receive special attention. Although no general rule of preference is likely to be developed that can be applied to all shipments, both rail and pipeline service will be needed on an increasing scale. The study should provide useful background information and analysis for government and industry in approaching investment decisions in the mining and transportation industries.

Jan 1, 1975

By Beatrice L. Lukens, David Schlain, John D. Prater

"The electrolytic manganese process developed by the Bureau of Mines4/ and now in use in the commercial plant of the Electromanganese Corp. at Knoxville, Tenn., and in the Bureau of Mines pilot plant5/ at Boulder City, Nev., involves the electrolysis of a solution of manganese sulfate and ammonium sulfate in a diaphragm-type cell. Metallic manganese is deposited on the cathodes, and sulfuric acid is produced at the anodes.. The spent electrolyte contains, in addition to the sulfuric acid, approximately 30 percent of the manganese and most of the ammonium sulfate originally present in the feed solution. This spent solution is used to leach fresh ore that has previously been given a reducing roast. The resulting leach liquor is purified and returned to the cell.Since the presence of small amounts of certain impurities in the electrolyte may be very detrimental to the electrodeposition of manganese, the purification of feed solution is a very important step in the process. According to the purification method6/ now in use in the Bureau of Mines pilot plant at Boulder city, Nev., cobalt, nickel, iron, arsenic, lead, copper, etc., are removed by precipitation as sulfides at a pH of 6.0 to 6.5. Residual sulfides and colloidal material are removed from the resulting solution by ferric hydroxide formed by adding a small amount of iron sulfate and passing air through the solution. Feed solution purified in this way contains less than 1/2 mg.-per liter-of such impurities as arsenic, iron, cobalt, nickel, copper, etc., and is pure enough to give consistently excellent manganese deposits.Although this purification scheme has given satisfactory results at the Boulder City pilot plant knowledge of the specific effects of various impurities would be valuable. Such information would be useful in diagnosing the causes of cell room operating difficulties, and might aid in the recognition and correction of impurity difficulties arising from the use of new ores.. The purpose of this investigation was therefore, to study the effects of various concentrations of some common impurities.Since the effects of some impurities may not be apparent during short deposition periods and since harmful impurities often cause erratic results rather than consistently poor ones, it was believed that conclusions concerning the effects of impurities should be based upon the results of a fairly large number of 20- to 24-hour tests. Because of the time required for such tests, it was necessary to limit the scope of the work to a few of the more common impurities."

May 1, 1946

By John J. S. Sebastian

A laboratory-scale investigation was made of the basic problems involved in developing a ceramic heat exchanger to operate at high temperatures for using nuclear heat from gas-cooled process-heat reactors. Technical data were obtained on transferring heat by forced-convection from helium to air in a single-tube vitreous-alumina heat exchanger. Coolant air was passed through the annulus parallel with, and either concurrently or counter to, the flow of helium inside the tube. The data obtained pertain to removing heat from the helium. Average inside film coefficients were determined at mean surface temperatures of 200° to 1,570° F., inlet-gas temperatures of 1,450° to 2,665° F., and Reynolds numbers up to 560. The gas-to-surface temperature ratios were varied from 1.05 to 7.6. The tabulated results are shown in the appendix at the end of this report. The film coefficients of heat transfer were correlated by taking into account the physical properties of the helium at the average fluid temperature. With experimental conditions pointing to a laminar flow, the Nusselt number was found to decrease as the ratio of gas-to-wall temperature was increased to a value of 3. However, within the range tested, gas-to-wall temperature ratios above 3 did not affect the Nusselt number, regardless of the value of the Graetz number. Thus, beyond this point any increase in this ratio ceased to influence the heat-transfer relationship.

Jan 1, 1962