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By B. H. Clemmons

A field method has been devised for rapid determination of heavy minerals occurring in the unconsolidatod beach and dune sands. The method has been proved practical by usage in field evaluations of several hundred beach- and dune-sand samples in the Florida area. The simple equipment required and the techniques involved are described. Other data show that the method is relatively insensitive to variations in the mineralogical content or size distribution of the mixed heavy minerals contained in the samples tested. A modification of this procedure, found to be suitable for plant use in determining the relative purity of heavy-mineral flotation concentrates, is also described. A specific application is determination of the amount of feldspar-quartz in spodumene flotation concentrates. The results of the rapid evaluation techniques closely approximate those obtained by more precise laboratory procedures.

Jan 1, 1957

By T. L. Joseph

The size and accessibility of the Minnesota manganiferous iron ore deposits make them attractive as a potential source of ferromanganese, which is essential in the production of steel. For several years the Bureau of Mines has been conducting experiments to determine the feasibility of producing ferromanganese from these ores by a three-step process which involves (1) the smelting of the ores in the blast furnace to produce a high-phosphorus spiegel; (2) the treatment of the spiegel produced from step 1 in an electric or open-hearth furnace to separate the manganese from the phosphorus and the iron; and 3) the smelting of the high-manganese slag from step 2 to produce ferromanganese. The details of the first two steps of the process and the results of tests with the experimental furnaces have been given in previous reports.

Jan 1, 1931

By H. Kenworthy

A zinc-pyrite ore from the Gray deposit in Jo Daviess County, Ill., was successfully concentrated on a laboratory scale. Initially, drill cuttings were submitted for separation of zinc and iron concentrates. Subsequent to mine development, a large sample of coarse ore was submitted to ascertain its amenability to sink-float treatment to produce a low-grade zinc-iron concentrate and discard a clean tailing. The samples of ore were submitted to the Rolla Metallurgical Branch by the Mining Division of the Federal-Bureau-of Mines. They were obtained during the recent war as a part of the extensive government program to increase metal production through exploration for new mineral deposits and investigation of old mineralized areas. The first sample consisted of about 3,000 pounds of drill cuttings collected, during the Bureau?s churn and diamond- drilling program. The second sample was taken at a later date, after Tri-State Zinc, Inc., had opened the deposit and commenced milling the ore. This sample consisted of a ?ton-of mill feed crushed through 2 inches and collected over a period of 3 days.

Jan 1, 1949

By G. W. Jones

The operation of combustion engines of various types at high altitudes and other combustion processes at reduced pressures have made it desirable to determine limits of flammabilities -under these conditions. Experiments carried out by the Bureau of Mines have shown that although natural gas-air mixtures become more difficult to ignite as the pressure is reduced below atmospheric, with a suitable source of ignition the limits of flammability are as wide at 175 mm mercury absolute as they are at atmospheric pressure.

Jan 1, 1949

By G. S. Scott, G. W. Jones

Trichloroethylene (CHC1CC12) is an important solvent for fats , resins , bitumens, rubber , sulfur , and phosphorus . It is used extensively in drycleaning because of its low order of combustibility and has recently been proposed as an inhalation anaesthetic . Its physical properties have been described by Carlisle and Levine . It is usually considered a noninflammable material ; however , substances that are noninflammable when mixed with air are not necessarily noninflammable when mixed with oxygen . Thus , Hewer's statement that " Trichloroethylene*** is not inflammable under any circumstances , nor will its vapor explode when mixed in any proportion with air , oxygen, or nitrous oxide , " requires qualification , especially in anesthesia, where pure oxygen may at times be substituted for air , This report gives the results of tests made to determine the inflammability of trichloroethylene in various mixtures of oxygen and nitrogen . The trichloroethylene used was Eastman's No. 1300. The boiling point was given as 86 ° to 87 °C . The specific gravity and refractive index of the sample measured in this laboratory were , respectively, 1.45 and 1.4759 at 25 °C .

Nov 1, 1942

By H. D. Jacobs

The Bureau of Mines undertook a research program to insure an adequate supply of iron raw materials for future iron and steel making needs. A sample was obtained of oxidized taconite from the western Mesabi Range in Minnesota, and the metallurgical response of the taconite to beneficiation by a process that included selective flocculation-desliming-cationic flotation was evaluated. The sample contained 35.3 pct iron and represented approximately 2 billion tons of crude material. Selective flocculation and flotation were evaluated in a pilot plant with a feed rate of 900 Ib/hr. Concentrates averaging 61.7 pet iron and 5.1 pet silica were obtained, with an accompanying iron recovery of 67.2 pet. About 83 pct of the process water requirements were reclaimed from the slime and froth tailing and then recycled.

Jan 1, 1980

By M. J. Ferrante

Low-temperature heat capacities and high-temperature enthalpies were determined calorimetrically for Na2Cr04, A reversible transition was found at 700° K with an isothermal heat of transition of 2,263 cal/mole. High-temperature X-ray diffraction analysis showed that the transition was a crystal change from the low-temperature orthorhombic form to the high-temperature hexagonal form. At 795° K the hexagonal form had the parameters a, = 5.691 and co = 7.478 A. Powder diffraction data for the high-temperature form are given and possible structures discussed. The melting point was determined to be 1,065° K with a heat of fusion of 5,810 cal/mole. Enthalpy and entropy increments from this investigation were combined with other data from the literature to calculate enthalpies of formation, free energies of formation, and equilibrium constants of formation from 298° to 1,400° K. Equations that represent enthalpies above 298° K are given.

Jan 1, 1972

By W. W. Agey

The Calico silver-barite deposits near Barstow, Calif., are a potentially important resource. Exploration performed by two major mining companies out-lined large tonnages of ore that assayed at 2 to 3 ounces of silver per ton and 7 to 15 percent barite. Laboratory beneficiation work was done by the Bureau of Mines on four samples to develop methods for recovering the silver and/or barite. Cyanidation recovered from 47 to 60 percent of the silver from ore ground to approximately 100 percent minus 325 mesh. Salt roasting minus 10-mesh material, followed by regrinding and cyanidation, recovered 75 to 85 percent of the silver. From 75 to 90 percent of the barite was recovered in a plus 92-percent barite product from either the natural ore or from cyanidation residues. Salt roasting before cyanidation precluded recovery of the high-grade barite concentrate from the leach tails.

Jan 1, 1973

By Debra A. Griffith

The U.S. Bureau of Mines currently is researching the relationship between the level of back strength and the probability of low-back injury. This report is a review of the literature and statistics on over-exertion injuries. Overexertion continues to be a significant source of injury in metal and nonmetal mining, accounting for approximately 24 pct of all injuries yearly. These injuries, particularly to the lower back, can be very expensive in human and monetary terms. An examination of the accident data on overexertion injuries is necessary to provide a background for research into prevention and/or amelioration of those in-juries. The job categories outlined in the Accident Data Analysis data base most affected are "Mechanic/Electrician" and "Mill/Plant Worker." The age group most affected is "30-39" years, and the experience group most affected is "0-.99" years. The most prevalent type of overexertion injury is "Strain/Sprain," and the trunk is the body part most often involved in an overexertion injury.

Jan 1, 1994

By E. P. Youngman

Great Britain has never had a basic raining law such as is in force in most foreign countries. This lack may be due to the fact that, with the exception of gold and silver, all metals or minerals belong to the owner of the surface land. Even with respect to the precious metals, gold and silver, which are not abundant in Great Britain, the right of the Crown, though still technically acknowledged, is not always insisted unon. All other metals and minerals are vested in the ground landlord, who may sell, lease, or other¬ wise convey them. The State has little to do with the mining industry except in. regulatory and judicial matters. The Government must settle controversies and provide for easements, rights of way for railroads, roads, and canals, or, in general, effect the same control that it exercises over other industries. As mining was carried on in very early times in England, of necessity a certain legal procedure came into existence, which in effect was little more than a private contract between the owner of the mineral (whether an individual or the State) and the miner. The nature of such contracts, of course, has changed radically with the changed relations between classes, as England lias developed from the feudal into the modern State. From the medley of ancient procedure and custom, a concession system of mining in^its simplest form lias evolved. Of the earlier conditions. Van Wagenen says

Oct 1, 1931

By Jr. Watts, B. K. Cantrell, D. H. Carlson, K. L. Rubow

"Abstract — The use of diesel equipment in underground coal mines is controversial because the National Institute for Occupational Safety and Health (NIOSH ) regards ""wholediesel exhaust"" as ""a potential occupational carcinogen."" Threshold limit values (TLVs ) are recommended for the gaseous pollutants CO, CO2, NO, NO2, SO2 and some hydrocarbons emitted in diesel exhaust. There is, however, no TLV recommended for diesel exhaust aerosols (DEA) nor is there a standard method for sample these aerosols.The University of Minnesota and the USBM have collaborated to develop a personal diesel exhaust aerosol sampler (PDEAS) that utilizes size selective, partial impaction and gravimetric analysis. During the field tests of this sampler, numerous air quality measurements were conducted in underground coal mines that used diesel equipment. The objective of this report is to present these data and to assess the impact of diesel face haulage equipment on mine a quality.Air quality data were collected in four underground coal mines. The mines used continuous miners and diesel haulage equipment. Daily samples were collected at the section intake, haulage way and on haulage vehicles. Both full- and partial-shift samples were collected using a variety of aerosol instruments. These included the PDEAS and the micro-orifice uniform deposit impactor (MOUDI) that sample the mine aerosol diesel exhaust fraction. Two of the mines were also monitored for the major gaseous constituents found in diesel exhaust CO,CO2, NO, NC, and SO2. These measurements were made by either collecting bag samples for subsequent gas analysis or by Palmes dosimeters.Concentrations of CO, CO2, NO, NO2 and SO2 were well below regulated levels. The mine average DEA concentration determined by the PDEAS in the haulageway for the three mines surveyed was 0.79 mg/m4, with a standard deviation of 0.19 mg/m3 DEA contributed 65% of the respirable aerosol, at this location. These results were the same as the mean DEA concentrations calculated from size distribution measurements obtained using the MOUDI. This was 0.78 mg/m3, with a standard deviation of 022 mg/m3."

Mar 1, 1992

By G. B. Botsford

In August 1943 the Bureau of Mines began an investigation of the West Portal magnetite mines, which comprise the Swayze and Turkey Hill properties. The work included (1) traversing with a dip needle to record magnetic anomalies, (2) diamond drilling, and (3) sampling old mine dumps; it was completed in April 1944. The deposit consists of two parallel veins, which strike northeast and dip southeast. They carry magnetite in gneiss and schist. The Swayze mine was discovered in 1867 and closed in 1889, while the Turkey Hill mine was opened in 1872 and closed in 1887. The dip-needle survey covered 266 acres. The diamond drilling comprised 11 holes totaling 4,910 feet from which 142 samples were taken for chemical analyses. Old mine dumps were sampled at 52 points for chemical and magnetic analyses.

Jan 1, 1948

By A. F. Colombo, D. W. Frommer

Bench- scale tests were made to determine the applicability of flotation as a means of upgrading finished and semifinished magnetic concentrates prepared from reductively roasted iron ores . Both anionic and cationic flotation methods were used to remove siliceous gangue from the magnetic concentrates and produce upgraded products . Seven magnetic concentrates , containing from 6.7 to 13.7 percent SiO2 , were improved by the flotation treatment , yielding final concentrates containing less than 6.0 percent Si02 . Cationic flotation methods were studied on four of the seven samples ; of this group only one sample yielded better results by cationic flotation than by the anionic method .

Jan 1, 1964

By F. N. Kissell, C. H. Elder, C. M. McCulloch

The applicability of the "direct method" for determining the methane content of virgin coalbeds was tested. Preliminary results indicate that the direct method, when applied to exploration cores, can be successfully used to estimate coalbed gas content and also approximately predict the total gas emission from a prospective mine located in the coalbed at the exploration site.

Jan 1, 1973

By Edward M. Kawenski

Tests were made in the Bureau of Mines Experimental Coal Mine on stop-pings similar to those used in operating coal mines to obtain information on air leakage through the face and the rupture strength of a stopping subjected to a pressure differential. Block stoppings were made from cinder, slag, and gravel aggregates with and without mortared joints and coatings. Sheet stop-pings were uncoated brattice cloth and nylon or brattice cloth and expanded metal-lath coated with asphalt, latex, mortar, or rigid urethane foam. Limited data were obtained on air through stoppings subjected to simulated roof convergence and to shock forces created by the firing of an adjacent charge of explosive. The pressure differential required to rupture stoppings was determined. shows that coating the face of a stopping effectively reduces ail: leakage. Block stoppings, particularly those with mortared joints, are most resistant to pressure and shock forces than are sheet stop-pings. Where ground movement is a factor, sheet stoppings leak less air than block stoppings.

Jan 1, 1965

By Gerald T. Homce, Michael R. Yenchek, H. Kenneth Sacks, James C. Cawley

Accidents occur when least expected, from sources that we rarely anticipate and with outcomes that can vary greatly. Anyone who has ever been involved in an automobile accident knows, the transition from driving comfortably and safely down a highway to being involved in a potentially life-threatening situation can occur in a heartbeat. Accidents on the job are no different. The mining industry has a relatively small number of electrical injuries, compared to industries such as construction or agriculture, due to the small total employment in mining. Mining does, however, have one of the highest occupational electrocution rates of any U.S. industry, at 2.8 for every 100,000 workers per year. This is approximately four times the average for all industries. Data from the Mine Safety and Health Administration (MSHA) shows that 75 electrical fatalities occurred in the mining industry between 1990 and 1999. Of these, at least 17% involved high-reaching mobile equipment that contacted overhead power lines.

By E. C. Lane

The motor gasoline that is bring marketed in the United States this stunner is slightly more volatile than that sold a year ago. During the past eight years the Bureau of Mines has made semi-annual surveys of the gaoline marketed in the United States, the survey just completed being the sixteenth in the series. The cities in which samples have been collected have been chosen as representative of the more important marketing territories as it is obviously impracticable to obtain a sample of every gasoline sold in the entire country.

Jan 1, 1927

By George S. Rice, J. W. Paul, E. H. Denny

Data assembled by the Bureau of Mines , coupled with requests from coal companies , have emphasized the desirability of establishing standardized specifications for brattice cloth with particular respect to durability and fireproofing . Brattice cloth is a canvas or other material , often covered with some fireproofing composition , which is used extensively in coal mining for temporarily deflecting air into pillar workings and maintaining ventilation at the working faces . These specifications will be established , it is planned , through a cooperative program in which the U. S. Bureau of Standards will make a series of tests of various brattice cloths treated with respect to fire- resisting qualities and the U. S. Bureau of Mines will continue to assemble field data on the use of brattice cloth . Plans now are being made for this cooperative work. Without attempting to make a complete survey , the Bureau of Mines has made preliminary studies and investigations , and verious representative coal - mining companies have furnished detailed information . The information thus gained will be used as the basis for the cooperative investigation , but the Bureau of Mines would welcome additional information from mine operators on the character and weight of brattice cloth , conditions of use , durability , quantity employed and price . Such information should be sent to the Director , Bureau of Mines , Washington , D. C. The mine operator is interested in procuring at reasonable cost a brattice cloth with lasting fireproofing quality and of as great durability and strength as possible . There has been a lack of assembled data and knowledge regarding the subject , but the Bureau of Mines feels that this lack of knowledge may be overcome if the coal -mining companies will lend their hearty support to the cooperative investigation and submit information relative to the use of brattice cloth in their own properties . Information contained in this report is based on data obtained from coal operators in bituminous districts of Pennsylvania , Alabama , Utah , Indiana , Illinois , Colorado and Nova Scotia .

Feb 1, 1923

By R. Karl Zipf, Z. T. Bieniawski

"A set of fracture profile photomicrographs is presented for fractures generated under mixed mode loading of the Pittsburgh coal. The fractal dimension is used· to characterize the irregularity of these profiles and a tentative relationship is presented between the fractal dimension and the fracture toughness. Surface roughness appears to depend solely on the stress intensity and no other dependence was observed with fracture loading mode, loading rate· or specimen orientation. Observations of crack bifurcations.in fracture profiles can indicate crack growth direction whereas direct surface observations generally cannot in materials such as rock and coal.1 INTRODUCTIONThe production of fine fragments of material as a result of some loading event occurs in many industrial processes. In crushing and grinding, the efficient production of fine fragments is the desired end result; .however, in coal cutting, the production of fine fragments may lead to high levels of respirable dust in the immediate atmosphere with the danger of human lung diseases. Two of the most important sources of fragments in the 1 to 10 micron size range during a cutting process are 1) severe crushing in a zone near the loading tool and 2) subsequent shearing along major crack surfaces that form the larger fragments during material reduction. These and other sources of fine fragments generation are discussed by Roepke (1984) and Zipf and Bieniawski (1986). The physical character of the nearly created major crack surfaces is believed to have a strong influence on the amount of fine fragment generation that occurs during subsequent shearing movement. When the major large fragments initially form, they are ""locked"" in place by the irregular character of the new fracture surface. Only after some relative motion has occurred between fragments are they actually liberated, and the net result is the formation of additional fine fragments. The fine fragmentation is not necessarily limited to the shearing of high points from the macrocrack surf ace since material remaining in the wake of the crack tip is damaged to a substantial depth below the actual crack surface."

Aug 31, 1989

By H. J. Heinen

Excellent gold recovery was demonstrated in a laboratory-scale leaching test on waste material from an open-pit mine in northeastern Nevada. An injection system of leaching was applied in which the sodium cyanide solution was introduced into the interior of the dump at selected points. Dissolution of gold from the waste material, which assayed 0.06 ounce gold per ton, was readily achieved because the gold occurred as submicroscopic particles in a porous host rock. Gold recovery of 80 percent was obtained in 11 days from material crushed to 1 inch in size, and recovery was 90 percent after 21 days.

Jan 1, 1969