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By A. B. Hooker

Nineteen of the installations were on rental contracts 1.L."'1der whtch the lamps belong to the lamp company and are rented by t.½em to the mine operatj.nt; company. · The other nine installations had been upon an O\Vnership-rental basis, by which the lamps had become the property of the renter at the end of 5 years. Five of t.11e rentec installations were en a special contract calling for a guaranteed light output. These contr2.cts were based upon certified . initial performance, with the provision that the lamps be replaced whenever periodic tests of fully charged lamps, taken at random from t..h.e charge racks, showed a light output of less than 80 percent of the certified performance.

Jan 1, 1942

By W. E. Webb, R. H. Church, W. G. Hopkins

The development of systems for location of miners who have become entrapped following a mine disaster has been one of the major research goals in the Bureau of Mines. This study details the preliminary development of such a system. Current technologies for locating trapped miners from the surface are either simple direction, finders or time difference pulse systems that have accuracy Limitations. Developing technologies using full vector field measurements at several receiving points are currently being studied. The necessity of measuring field strength with great accuracy can be a drawback in these systems. A system that operates with continuous wave radio signals, whose phase differences can be measured accurately even in weak signal conditions, greatly improves the location accuracy. A microcomputer would be used, in conjunction with the system, to gather and manipulate the data to automatically pinpoint the location of the trapped miner. Comparison of this system with existing technology indicates a favorable accuracy/complexity ratio for the phase difference of arrival technique.

By M. E. Tyrrell, J. Koster

This work was undertaken to determine the feasibility of making mixed diborides of two metals directly from the metal oxides , boron carbide and carbon . The diborides (Ti , V ) , B₂ , (Ti , Cb) B₂ , and ( Ti , Ta ) B₂ were prepared in a crucible resistance furnace at 2,100 ° C , and X- ray- diffraction analyses showed each was a homogeneous solid solution containing approximately equal molar contents of the given diborides . The diboride powders were cold - pressed ; sintered to 2,300 ° C , and evaluated for mechanical strength , rate of oxidation , and resistance to molten metals . The diboride ( Ti , Ta ) B₂ exhibited the best mechanical properties ; the diboride ( Ti , Cb ) B₂ , the lowest cumulative rate of oxidation . The mixtures were stable in the presence of molten aluminum and copper but were attacked by molten Ti , Zr , and Cr .

Jan 1, 1964

By A. S. Moore

The Bureau of Mines is doing research and development work on removing acid-gas impurities from synthesis gas made directly from coal. Since conventional gas scrubbers, packed towers and bubble-cap columns, are expensive to construct and difficult to operate with viscous solutions, one aspect of the work was developing a compact, agitated, gas-liquid contactor for use with concentrated absorbents. The efficacy of the agitated contactor for absorbing carbon dioxide in diethanolamine increased with increasing solution rate, turbine speed, diethanolamine concentration, and carbon dioxide concentration in feed gas, and with decreasing liquid-gas ratio. It was unaffected by pressure between 200 and 300 p.s.i.g. and little affected by temperature between 115 and 190° F.

Jan 1, 1961

By Oliver Bowles

"The American Consul at Guatemala City reports that the Guatemala Marble Mining Company is preparing to operate a marble quarry about 13 miles from the railroad station of Zacapa, which station is a little over 100 miles from Puerto Barrios, the nearest port from which the product may be shipped. The deposit is extensive, and though somewhat broken up in places, great quantities of sound marble are available. It is claimed that the marble is equal in quality to the best product of the Italian Carrara quarries.Access to the quarry by rail is obtained by a spur track of the International Railways of Central America (Ferrocarril Internacional de Centro America) from Marmol, 3 miles south of Zacapa. This spur is about 5 miles long and terminates at the foot of the mountains. A double-track incline cable-way 2000 feet in length has been constructed to bring the marble down the mountain. From the top of the incline to the quarry there is a railway six miles in length over which the rock will be hauled by two side-geared Shay locomotives."

Mar 1, 1920

By Jr. Kauffman

The data contained in this report were obtained incidental to the Bureau of Mine's investigation of the lime-soda sinter process as applied to the recovery of alumina from siliceous bauxite, kaolin, and other high aluminous materials. The Bureau of Mines was charged by Congress to investigate processes for the production of aluminum from domestic low-grade ores. The Eastern Experiment Station at College Park, Md., conducted laboratory and pilot-plant investigations of the recover-y of alumina by the lime-soda sinter process. Reports by the College Park staff covering the recovery of alumina from these sources have been published. The lime-soda sinter process involves the sintering of the finely ground siliceous bauxite or clay with limestone and soda ash in a rotary kiln. During the sintering the alumina supposedly reacts with the soda ash to form soluble sodium aluminate and the silica combines with the lime to form the insoluble orthosilicate. In the early stages of the investigation it was considered desirable to know the temperatures at which the phase changes occurred during the sintering operation. The total time involved in the passage of any given portion of the charge through the kiln was 28 minutes. The exposure time of the charge to temperatures above 600° C. (decomposition temperature of kaolinite) was, roughly, half the total. The exposure to the full temperature of the kiln, 1,100° C was only 3 minutes. (Subsequently, the maximum kiln temperature and retention time were increased.)

Jan 1, 1949

By R. L. Hopkins, H. T. Rall, H. J. Coleman, C. J. Thompson

Two methods were tested for separating sulfur compounds in certain petroleum fractions into types . Such separation is preliminary to identifying the compounds . Each method involved extraction of sulfides from petroleum sulfur concentrates . In the first method , the sulfur concentrate was reacted with methyl - ptoluenesulfonate to form sulfonium compounds from which unreacted portions of the sample were removed by washing with solvent . The sulfides then were recovered by heating the sulfonium compounds with anhydrous triethanolamine . The second method consisted of passing anhydrous hydrogen iodide into a n-butane solution of the sample cooled in dry ice , whereupon the hydrogen iodide adducted with the sulfides to form sulfonium compounds . These adducts separated as crystalline solids or , more frequently , as glassy viscous liquids . The sulfide was regenerated by adding water to the filtered sulfonium compound and was recovered by steam distillation or by extraction with pentane . These methods have been evaluated , using individual pure sulfur compounds and blends of sulfur compounds . They also have been applied successfully to separating sulfides from sulfur concentrates derived from petroleum fractions .

Jan 1, 1964

By R. O. Dannenberg

Exploratory research was conducted to ascertain the feasibility of recovering beryllium from Spor Mountain, Utah, ore by the sodium fluosilicate (Na2SiF6) method used industrially for processing beryl. Na2SiF6 requirements to form water-soluble salts of beryllium were determined for three different samples--two clayey ores containing 0.6 and 1.3 pct BeO, respectively, and a calcareous ore containing 0.6 pct BeO. The ores were sintered with Na2SiF6 at 750° C for 3 hours. About 80 pct of the beryllium was rendered water soluble by sintering the 0.6-pct BeO ores with 30 and 40 lb Na2SiF6 per lb BeO contained in clayey and calcareous ores, respectively. The higher grade 1.3-pct BeO clayey ore required only 20 lb Na2SiF6 per lb BeO to solubilize over 80 pet of the beryllium. As the 0.6-pct BeO clayey ore was possibly the most representative of the deposit as presently delineated, leach liquor prepared from this sample was treated to recover beryllium salts. About 60 pet of the beryllium contained in the ore was recovered as beryllium hydroxide, which then was calcined to yield a 99-pct BeO final product by means of the following operations: (1) Sintering with Na2SiF2, (2) leaching with water, (3) precipitating crude Be(OH)2 by adding NaOH, (4) filtering to separate the hydroxide from the NaF solution, (5) redissolving the crude Be(OH)2 in excess NaOH, (6) filtering to reject caustic-insoluble impurities, and finally (7) boiling the Na2BeO2 filtrate from (8) to precipitate pure Be(OH)2. Reagent consumption was 49 lb Na2SiF6 per lb BeO recovered and 17 lb NaOH per lb BeO.

Jan 1, 1963

By David A. Lipton

In 1980, the U.S. Bureau of Mines conducted a mineral survey of the 23,500 acre Garcia Mountain RARE II area (No. 5107) in the Los Padres National Forest. Bureau of Mines data indicate a low potential fur gold, silver, and mercury resources. Twenty-nine placer samples, representative of small yardages, showed small amounts of gold or other economic mineral values. Mercury deposits in faulted siliceous rocks in the Franciscan Formation occur north of the area. Similar rocks are in the southwest part of the study area, but apparently contain no mercury deposits. Geothermal and oil and gas potential is low.

Jan 1, 1982

By D. A. Stanley

The Bureau of Mines is investigating a method of dewatering flocculated fine-particle waste that involves treating the waste with a high molecular-weight polymer such as polyethylene oxide (PED) followed by dewatering on a static screen and/or in a trommel. Dilution of the polymer solution used for dewatering and use of the ion-exchanged form of the montmorillonite clay were found to be major factors determining the amount of polymer required to dewater clay-containing slurries. The amount of polymer, A, required to dewater ion-exchanged montmorillonite can be described by the equation, An = kC + b where n, k, and b are empirical constants and C is the concentration of the polymer solution used for dewatering. Clays that require large amounts of polymer for dewatering also dewater to a lower solids content. The concentration of the polymer solution is important because it affects the radius of the polymer coil in solution and hence its ease of transfer to a bridging configuration by shear. The constant, n, a function of the charge to hydrated radius of the exchange ion, relates to the strength of the bond between the polymer and the surface of the clay through a water bridge. The constant k is related to the hydrated radi-us for sodium or to the unhydrated radius for the other exchange ions.

Jan 1, 1986

By George H. Schnakenberg

This Bureau of Mines publication describes a passive personal sampling device for N02 in air, developed by the New York University Medical Center under Bureau Grant G0133066. The sampler has been successfully demonstrated in the field and in the laboratory. In corroborative laboratory trials the agreement with reference method is excellent. The overall accuracy is approximately ±5 pct of reading to a precision of about ±l pct. All evidence indicates that these samplers should indicate the time-weighted-average N02 concentration to the above accuracy and precision equally well in the field since effects of wind velocity and relative humidity are negligible and the effects of temperature are about 0.1 pct per °F. The duration of exposure and the approximate temperature are the only data that need to be collected in the field. A two-step analysis procedure in field or service laboratory is then used to obtain the total cumulated exposure to N02 in parts per million-hours (ppm times hours), which can be converted to the time-weighted-average concentration of N02 in ppm by dividing cumulated exposure by the duration of the exposure.

Jan 1, 1976

By Richard S. Olsen

Prior work by the Bureau of Mines demonstrated a feed preparation method that eliminates the formation of slime during leaching of calcined kaolinitic clay and makes leached residues fast settling and easy to filter. Nitric acid leaching rates determined for calcined kaolinitic clay prepared by this method were found to correspond to a zero-order reaction model for both batch and continuous, stirred-tank leach-ing. A rate constant of 0.136 min-1 was determined. Separation of solid residues from the reacted slurry was examined, and filtration rates were determined. Permeabilities of the flocculated, leached residues were around 51 darcys, or 5.0 x 10-7 cm2 for laminar flow through 4-ft-deep beds.

Jan 1, 1983

By M. K. Quinn, A. W. Khair

"This paper presents an analysis of respiraple dust generation due to the action of a continuous miner. Underground coal cutting by a drum-type continuous miner was simulated in the laboratory using a specially designed unique automated rotary coal cutting simulator (ARCCS). An analysis of -400 mesh particles was done on gravity collected material. Samples of entrained dust were collected through the use of cascade impactors. Both samples were analyzed for size distribution and particle shape. Using the simulated coal cutter permitted variation of operating and in-situ parameters to provide information on the effects on generation of -400 mesh particles. In these tests coal blocks with an approximate dimension of 18 in. x 15 in. x 6 in. (45.7 cm x 38.1 cm x 15.2 cm) were first subjected to confining pressures, equivalent to in-situ conditions. Such blocks were then cut by the cutting head of the ARCCS, thus simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-situ and operating parameters a number of other parameters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photo¬graphed and a velocity survey was conducted by using a sonic technique. At the end of each experiment the cutting paths of the bits in coal were photographed using an optical microscope with an attached camera.IntroductionThe continuous-mining machines introduced in the 1950's now account for more than half the production of coal from underground mines. Unfortunately, these continuous miners, designed for increased productivity, have also increased the concentration of respirable dust in mines. As a result, the Federal Coal sine Health and Safety Act of 1969 was enacted to enforce on the coal operators that the airborne respirable dust not exceed 2 mg/m3, and was intended to reduce the incidence of coal workers pneumo-coniosis. This plus the other aspects of the legislation and the subsequent monitoring and enforcement by MSHA made it very imperative that the coal operators provide a relatively healthier and safer working environment for the coal miners. Since 1970, the Federal government has paid over 11.7 billion dollars to more than 470,000 miners with coal workers pneumoconiosis and their survivors (Newmeyer, 1981). These regulations, coupled with the assessment of the continuing burden on miners, the mining industry and taxpayers appear to have provided an impetus for the mining community towards comprehending the different parameters that influence dust generation and entrainment."

Jun 1, 1988

By J. H. Maysilles

The Bureau of Mines is conducting research on various technologies to recover alumina from domestic resources for feedstock to existing aluminum smelting capacity as a means to reduce dependence on imported bauxite, which represents 93 pct of U.S. aluminum requirements. One of the more promising technologies being investigated is the hydrochloric acid leaching of kaolinitic clay. In the hydrochloric acid leaching technology, alumina is recovered from iron-free aluminum chloride leach liquor and separated from impurity elements by sparging the liquor with HC1 gas to crystallize aluminum chloride hexahydrate (ACH). A large-scale crystallizer with a 336-gallon usable volume was constructed and operated to obtain engineering and design data for potential scale up and to demonstrate the ability of the technology to produce specification grade alumina. Test campaigns involving about 1,400 hours of operation were completed. ACH meeting all chemical purity requirements could not be produced by a single crystallization, but was produced by recrystallizing the product from the calcined kaolin clay leach liquor. Product crystals with a size distribution of more than 80 pct plus 100 mesh and 65 pct plus 65 mesh were made at a rate of 10 pounds of ACH/(hr)(ft3). The zirconium tube heat exchanger used to maintain constant process temperature operated with an over-all heat transfer coefficient of 420 to 500 BTU/(hr)(ft2)(°F).

Jan 1, 1981

By Jr. Hill

Laboratory metallurgical treatments of three high-iron bauxite ores from Arkansas were conducted to determine the relative effectiveness of experimental methods for recovering alumina and a commercially acceptable iron concentrate. The standard for evaluating recoveries from experimental processes was the Al2O3 recovery from Bayer digests of the crude ores; recoveries from digestion of the three ores were 74.1, 87.4, and 88.7 percent. Flotation, magnetic separation, or various combinations of digestion, calcination, and reduction-sintering, leaching, and magnetic separation of leach residues failed to produce Al2O3 recoveries as high as the standard. A high-iron-bearing fraction, containing between 68 and 78 percent of the total iron, was produced in a three-phase treatment involving a caustic, lime reduction-sinter of the crude ore, water extraction of Al2O3 from the sinter, and magnetic separation of the leach residue.

Jan 1, 1967

By R. V. Lundquist, H. Leitch

The solubility characteristics of three calcium aluminates , 12Ca0 · 7A120½ 3Ca0 A1203 , and 4Ca0 A12 03 Fe2O3 , were determined in water and in solutions of NaOH and Na₂ CO₂ to more clearly define their role in relation to the recovery of aluminum by the lime sinter and the lime - soda sinter processes . The calcium aluminates were prepared by sintering stoichiometric mixtures of CaCO3 , Al2O3 3H20, and Fe 0 at 1,375 ° C. The rates and extent of aluminum extractions were determined . The aluminum extractions from the aluminates were dependent on the presence of carbonate ions in the leach solutions , temperature , time , leach solution composition , and solid - liquid ratio of the slurry . The aluminum extracted from the calcium aluminates in water and in NaOH solutions varied from 4.6 to 22.9 percent . Virtually , complete extraction could generally be obtained for 12Ca0.7A120 and 4Ca0.A12 03 • Fe₂ 03 ; in one instance it was obtained for 3Ca0.A1203 , when an excess of carbonate ions was present over that required for the conversion of all of the calcium in the aluminates into CaCO3 . In some cases of poor aluminum recoveries , extractions could be improved by regrinding and releaching the solid residues .

Jan 1, 1964

By Laurel A. Powers

The Bureau of Mines process for recovering Ni and Co from low-grade domestic laterites uses a reduction roast followed by an ammonia, ammo-nium sulfate leach. This investigation examined the waste streams of the process for their potential environmental impact and focused on the laterite residue produced. The U.S. Environmental Protection Agency's extraction procedure (EP) toxicity tests and column leaching showed that leachable metal concentrations would be low enough so that the residue would not be considered a hazardous waste under present definitions. Under nonacid leaching conditions, about the same amount of metal was extracted from laterites as from their residues, and the leachates were similar to water samples from an undisturbed laterite deposit. Washing tests on the laterite residue showed that ammonia and ammonium sulfate concentrations were reduced according to equilibrium stage calculations, resulting in residues that would be acceptable for revegetation. With water washing only, the residue would not be considered a hazardous waste even though significant amounts of Ni and Co were absorbed from entrained leach solution onto the residue. Washing first with fresh leach solution and then with water prevented this absorption and thus improved the overall metal recovery.

Jan 1, 1983

By J. R. Ross

Techniques for recovering scandium from uranium plant iron sludges and from wolframite concentrates are described. The best procedure found comprised (1) dissolution with sulfuric acid, (2) preliminary concentration by solvent extraction with a primary alkyl amine, (3) further enrichment and purification by a combination of ion exchange, solvent extraction, chemical precipitation, and calcination. Recovery of scandium from these raw materials, which contained 0.058 and 0.14 percent scandium, ranged from 83 to 90 percent in products analyzing 99.6 to 99.9 percent scandium oxide.

Jan 1, 1965

By Leland E. Paulson

This investigation examined the feasibility of altering the inorganic component of North Dakota lignite by ion exchange. Lignite of specific size consist was washed with various ionic solutions and examined for evidence of exchange. Ions of higher valance substituted preferentially at equivalent concentrations. Results indicate that a major portion of the inorganic material associated with lignite is combined in exchangeable form with the organic component. Particle size of the treated coal is a critical factor in determining the rate of exchange. The data indicate that monovalent ions are easily replaced by divalent and trivalent ions, and the presence of ionic material in slurries containing finely divided lignite significantly increases filtration rates.

Jan 1, 1968

By John Owens, Hamid Maleki

Efficient and safe use of mobile roof supports (MRS) depends on the interaction between the MRS and coal strata. Of particular interest to this study are the mechanics of strata deformation as influenced by geologic conditions, pillar extraction methods, and MRS load-bearing capabilities. To provide a better understanding of the mechanics of strata deformation, the authors have collected and reviewed measurements of convergence and stress in one western U.S. mine and have completed pseudo-three-dimensional, boundary-element modeling for two typical pillar-pulling plans. Stress distribution in the mine roof above pairs of MRS’s was calculated to demonstrate how MRS’s contributed to the control of roof block movements. It was shown that overall stress and roof-floor convergence patterns were most influenced by the stiffness of coal-measure rocks and by pillar-pulling sequences and layouts. MRS’s and other support systems play a critical role in controlling the stability of both the immediate roof and the middle roof for a distance of up to 18 m (60ft) above the seam. MRS’s provide unique ground control advantages over other types of secondary support by significantly reducing the time between mining and installation of secondary support. Although MRS’s are similar to posts in stiffness and capacity, they are more effective than posts under static loads because they can yield and still maintain loads at near-peak capacity, whereas posts fail and loose their ability to limit mine roof deformation.